ESS Tech (GWH) S-1 27 Dec 21 IPO registration Financial data

Cover Page

Cover Page	9 Months Ended
	Sep. 30, 2021
Cover [Abstract]
Document Type	S-1
Entity Registrant Name	ESS TECH, INC.
Amendment Flag	false
Entity Central Index Key	0001819438
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false

Condensed Balance Sheets

Condensed Balance Sheets - USD ($)	Sep. 30, 2021	Dec. 31, 2020	Dec. 31, 2019
CURRENT ASSETS:
Cash and cash equivalents	$ 8,019,000	$ 4,901,000	$ 18,290,000
Restricted cash	1,217,000	1,167,000
Prepaid expenses and other current assets	6,506,000	793,000	658,000
Total current assets	15,742,000	6,861,000	18,948,000
Property and equipment, net	2,007,000	1,836,000	1,663,000
Restricted cash	75,000	326,000	529,000
TOTAL ASSETS	17,824,000	9,023,000	21,140,000
CURRENT LIABILITIES:
Accounts payable	3,037,000	522,000	697,000
Accrued and other current liabilities	4,595,000	2,194,000	1,826,000
Notes payable, current	23,415,000	5,678,000	365,000
Total current liabilities	31,047,000	8,394,000	2,888,000
Notes payable, non-current	2,253,000	19,000	463,000
Other non-current liabilities	3,662,000	2,258,000
Customer deposits		2,258,000	2,207,000
Derivative liabilities	248,450,000	22,911,000	11,379,000
Warrant liabilities		3,329,000	1,989,000
Total liabilities	285,412,000	36,911,000	18,926,000
COMMITMENTS AND CONTINGENCIES (NOTE 5)
Class A ordinary shares subject to possible redemption		215,583,980
REDEEMABLE CONVERTIBLE PREFERRED STOCK:
Redeemable convertible preferred stock	90,073,000	34,372,000	34,372,000
STOCKHOLDERS' DEFICIT:
Common stock, value	1,000	1,000	1,000
Common stock warrants		153,000	153,000
Additional paid-in capital	2,516,000	1,079,000	762,000
Accumulated deficit	(360,178,000)	(63,493,000)	(33,074,000)
Total stockholders' deficit	(357,661,000)	(62,260,000)	(32,158,000)
TOTAL LIABILITIES, REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' DEFICIT	17,824,000	9,023,000	$ 21,140,000
ACON S2 Acquisition Corp [Member]
CURRENT ASSETS:
Cash	1,177	470,073
Prepaid expenses	160,186	215,972
Total current assets	161,363	686,045
Other assets	40,741	136,991
Investments held in Trust Account	250,016,847	250,004,454
TOTAL ASSETS	250,218,951	250,827,490
CURRENT LIABILITIES:
Accounts payable	222,866
Accrued expenses	1,428,762	99,107
Accrued expenses - related party	130,000	40,000
Working capital loan - related party, at fair value	361,751
Total current liabilities	2,143,379	139,107
Deferred underwriting commissions	8,750,000	8,750,000
Derivative warrant liabilities	20,217,050	21,354,400
Total liabilities	31,110,429	30,243,507
COMMITMENTS AND CONTINGENCIES (NOTE 5)
Class A ordinary shares subject to possible redemption		250,000,000
STOCKHOLDERS' DEFICIT:
Preference shares
Additional paid-in capital	94	94
Accumulated deficit	(30,892,197)	(29,416,736)
Accumulated deficit		(29,416,642)
Total stockholders' deficit	(30,891,478)	(29,416,017)
TOTAL LIABILITIES, REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' DEFICIT	250,218,951	250,827,490
ACON S2 Acquisition Corp [Member] | Class A ordinary shares
CURRENT LIABILITIES:
Class A ordinary shares subject to possible redemption	250,000,000	250,000,000
STOCKHOLDERS' DEFICIT:
Common stock, value
ACON S2 Acquisition Corp [Member] | Class B ordinary shares
STOCKHOLDERS' DEFICIT:
Common stock, value	625	625
Total stockholders' deficit	$ 625	$ 625

Condensed Balance Sheets (Paren

Condensed Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2021	May 07, 2021	Dec. 31, 2020	Sep. 30, 2020	Sep. 21, 2020	Dec. 31, 2019
Common stock, par or stated value per share	$ 0.0001	$ 0.0001	$ 0.0001			$ 0.0001
Common stock, shares authorized	79,000,000	79,000,000	79,000,000			79,000,000
Common stock, shares, issued	9,125,954		7,134,668			7,060,668
Common stock, shares, outstanding	9,125,954		7,134,668			7,060,668
Preferred stock, par or stated value per share		$ 0.0001
Preferred shares, authorized		62,072,064
ACON S2 Acquisition Corp [Member]
Temporary equity, par or stated value per share			$ 0.0001	$ 0.0001
Temporary equity, redemption price per share	$ 10		$ 10
Common stock, shares authorized			0
Preferred stock, par or stated value per share	$ 0.0001		$ 0.0001	0.0001
Preferred shares, authorized	5,000,000		5,000,000
Preferred shares, issued	0		0
Preferred shares, outstanding	0		0
Redeemable Preferred Stock [Member]
Temporary equity, par or stated value per share	$ 0.0001		$ 0.0001			$ 0.0001
Temporary equity, shares authorized	62,072,064		61,436,037			61,436,037
Temporary equity, shares issued	38,768,389		32,865,949			32,865,949
Temporary equity, shares outstanding	38,768,389		32,865,949			32,865,949
Temporary equity, liquidation preference	$ 61,392		$ 46,391			$ 46,391
Class A ordinary shares | ACON S2 Acquisition Corp [Member]
Temporary equity, par or stated value per share				0.0001
Temporary equity, redemption price per share	$ 10		$ 10
Temporary equity, shares outstanding	25,000,000		25,000,000
Common stock, par or stated value per share	$ 0.0001		$ 0.0001	0.0001	$ 0.0001
Common stock, shares authorized	500,000,000		500,000,000
Common stock, shares, outstanding	25,000,000		25,000,000
Class B ordinary shares | ACON S2 Acquisition Corp [Member]
Common stock, par or stated value per share	$ 0.0001		$ 0.0001	$ 0.0001
Common stock, shares authorized	50,000,000		50,000,000
Common stock, shares, issued	6,250,000		6,250,000
Common stock, shares, outstanding	6,250,000		6,250,000

Condensed Statements of Operati

Condensed Statements of Operations and Comprehensive Loss - USD ($)	2 Months Ended	3 Months Ended		5 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Operating expenses
Research and development		$ 7,672,000	$ 3,935,000		$ 19,546,000	$ 8,903,000	$ 12,896,000	$ 6,660,000
Sales and marketing		1,048,000	279,000		2,261,000	876,000	1,158,000	908,000
General and administrative		2,316,000	630,000		7,667,000	2,178,000	3,338,000	2,321,000
Total operating expenses		11,036,000	4,844,000		29,474,000	11,957,000	17,392,000	9,889,000
Loss from operations		(11,036,000)	(4,844,000)		(29,474,000)	(11,957,000)	(17,392,000)	(9,889,000)
Other income (expense):
Interest expense, net		(1,582,000)	(38,000)		(1,693,000)	(106,000)	(132,000)	(1,019,000)
Gain (loss) on revaluation of warrant liabilities		(2,949,000)	24,000		(17,753,000)	78,000	(1,296,000)	(341,000)
Gain (loss) on revaluation of derivative liabilities		(36,703,000)	2,089,000		(248,691,000)	5,849,000	(11,532,000)	(19,000)
Other income (expense), net		945,000	(2,000)		926,000	(64,000)	(67,000)	(199,000)
Total other income (expense)		(40,289,000)	2,073,000		(267,211,000)	5,757,000	(13,027,000)	(1,578,000)
Net income (loss) and comprehensive loss		$ (51,325,000)	$ (2,771,000)		$ (296,685,000)	$ (6,200,000)	(30,419,000)	(11,467,000)
Series B Redeemable Preferred Stock accretion								(79,000)
Net loss and comprehensive loss to Common Stockholders							$ (30,419,000)	$ (11,546,000)
Net loss per share - basic and diluted		$ (5.82)	$ (0.39)		$ (35.08)	$ (0.87)	$ (4.28)	$ (1.64)
Weighted average shares used in per share calculation - basic and diluted		8,823,458	7,102,536		8,458,054	7,099,532	7,108,389	7,043,575
ACON S2 Acquisition Corp [Member]
Operating expenses
General and administrative	$ 41,854	$ 1,702,053		$ 708,829	$ 2,625,204
Loss from operations	(41,854)	(1,702,053)		(708,829)	(2,625,204)
Other income (expense):
Gain (loss) on revaluation of warrant liabilities		(2,232,690)		(1,854,400)	1,137,350
Financing costs – derivative warrant liabilities	(735,490)			(735,490)
Gain on marketable securities (net), and dividends held in Trust Account		4,925		4,454	12,393
Other income (expense), net	(735,490)
Total other income (expense)	(735,490)	(2,227,765)		(2,585,436)	1,149,743
Net income (loss) and comprehensive loss	$ (777,344)	$ (3,929,818)		$ (3,294,265)	$ (1,475,461)
Redeemable Class A Common Stock [Member] | ACON S2 Acquisition Corp [Member]
Other income (expense):
Net loss per share - basic and diluted				$ (0.15)
Weighted average shares used in per share calculation - basic and diluted				16,139,241
Non Redeemable Class A and Class B Common Stock [Member] | ACON S2 Acquisition Corp [Member]
Other income (expense):
Net loss per share - basic and diluted				$ (0.15)
Weighted average shares used in per share calculation - basic and diluted				6,250,000
Non Redeemable Class A Common Stock [Member] | ACON S2 Acquisition Corp [Member]
Other income (expense):
Net loss per share - basic and diluted	$ (0.08)	$ (0.13)			$ (0.05)
Weighted average shares used in per share calculation - basic and diluted	6,250,000	6,250,000			6,250,000
Shares Subject to Redemption | ACON S2 Acquisition Corp [Member]
Other income (expense):
Net loss and comprehensive loss to Common Stockholders	$ (293,337)	$ (3,143,854)		$ (2,374,665)	$ (1,180,369)
Net loss per share - basic and diluted	$ (0.08)	$ (0.13)		$ (0.15)	$ (0.05)
Weighted average shares used in per share calculation - basic and diluted	3,787,879	25,000,000		16,139,241	25,000,000

Condensed Statements of Redeema

Condensed Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($)	Total	ACON S2 Acquisition Corp [Member]	Common Stock [Member]	Common Stock Warrants [Member]	Additional Paid-In Capital [Member]	Additional Paid-In Capital [Member]ACON S2 Acquisition Corp [Member]	Accumulated Deficit [Member]	Accumulated Deficit [Member]ACON S2 Acquisition Corp [Member]	Redeemable Convertible Preferred Stock [Member]	Class B ordinary sharesACON S2 Acquisition Corp [Member]
Beginning Balance ,Shares at Dec. 31, 2018									16,590,261
Beginning Balance ,Value at Dec. 31, 2018									$ 15,897,000
Beginning Balance ,Shares at Dec. 31, 2018			7,030,668
Beginning Balance ,Value at Dec. 31, 2018	$ (20,793,000)		$ 1,000	$ 153,000	$ 660,000		$ (21,607,000)
Stock options exercised ,Shares	30,000		30,000
Stock options exercised ,Value	$ 6,000				6,000
Issuance of Series C Redeemable Convertible Preferred Stock ,Shares									16,275,688
Issuance of Series C Redeemable Convertible Preferred Stock ,Value									$ 18,396,000
Series B Redeemble Convertible Preferred Stock accretion									$ 79,000
Series B Redeemble Convertible Preferred Stock accretion	(79,000)				(79,000)
Stock-based compensation expense	175,000				175,000
Issuance of ordinary shares to Sponsor, Shares									16,275,688
Net income (loss)	(11,467,000)						(11,467,000)
Ending Balance ,Shares at Dec. 31, 2019									32,865,949
Ending Balance ,Value at Dec. 31, 2019									$ 34,372,000
Ending Balance ,Shares at Dec. 31, 2019			7,060,668
Ending Balance ,Value at Dec. 31, 2019	(32,158,000)		$ 1,000	153,000	762,000		(33,074,000)
Stock options exercised ,Shares			40,000
Stock options exercised ,Value	6,000				6,000
Stock-based compensation expense	251,000				251,000
Net income (loss)	(6,200,000)						(6,200,000)
Ending Balance ,Shares at Sep. 30, 2020									32,865,949
Ending Balance ,Value at Sep. 30, 2020									$ 34,372,000
Ending Balance ,Shares at Sep. 30, 2020			7,100,668							7,187,500
Ending Balance ,Value at Sep. 30, 2020	(38,101,000)	$ (26,899,096)	$ 1,000	153,000	1,019,000		(39,274,000)	$ (26,899,815)		$ 719
Beginning Balance ,Shares at Dec. 31, 2019									32,865,949
Beginning Balance ,Value at Dec. 31, 2019									$ 34,372,000
Beginning Balance ,Shares at Dec. 31, 2019			7,060,668
Beginning Balance ,Value at Dec. 31, 2019	$ (32,158,000)		$ 1,000	153,000	762,000		(33,074,000)
Stock options exercised ,Shares	74,000		74,000
Stock options exercised ,Value	$ 7,000				7,000
Stock-based compensation expense	310,000				310,000
Net income (loss)	(30,419,000)						(30,419,000)
Ending Balance ,Shares at Dec. 31, 2020									32,865,949
Ending Balance ,Value at Dec. 31, 2020									$ 34,372,000
Ending Balance ,Shares at Dec. 31, 2020			7,134,668							6,250,000
Ending Balance ,Value at Dec. 31, 2020	(62,260,000)	(29,416,017)	$ 1,000	153,000	1,079,000	$ 94	(63,493,000)	(29,416,736)		$ 625
Ending Balance ,Value at Dec. 31, 2020								(29,416,642)
Beginning Balance ,Shares at Jun. 30, 2020									32,865,949
Beginning Balance ,Value at Jun. 30, 2020									$ 34,372,000
Beginning Balance ,Shares at Jun. 30, 2020			7,100,668
Beginning Balance ,Value at Jun. 30, 2020	(35,407,000)		$ 1,000	153,000	942,000		(36,503,000)
Stock-based compensation expense	77,000				77,000
Net income (loss)	(2,771,000)						(2,771,000)
Ending Balance ,Shares at Sep. 30, 2020									32,865,949
Ending Balance ,Value at Sep. 30, 2020									$ 34,372,000
Ending Balance ,Shares at Sep. 30, 2020			7,100,668							7,187,500
Ending Balance ,Value at Sep. 30, 2020	(38,101,000)	(26,899,096)	$ 1,000	153,000	1,019,000		(39,274,000)	(26,899,815)		$ 719
Beginning Balance ,Shares at Jul. 20, 2020
Beginning Balance ,Value at Jul. 20, 2020
Issuance of Series C Redeemable Convertible Preferred Stock ,Shares										7,187,500
Issuance of ordinary shares to Sponsor		25,000				24,281				$ 719
Issuance of ordinary shares to Sponsor, Shares										7,187,500
Remeasurement adjustment on Class A ordinary shares subject to possible redemption		26,146,471
RemeasurementAdjustmentOnOrdinarySharesSubjectToPossibleRedemption	26,146,752	(26,146,752)				(24,281)		(26,122,471)
Net income (loss)		(777,344)						(777,344)
Ending Balance ,Shares at Sep. 30, 2020									32,865,949
Ending Balance ,Value at Sep. 30, 2020									$ 34,372,000
Ending Balance ,Shares at Sep. 30, 2020			7,100,668							7,187,500
Ending Balance ,Value at Sep. 30, 2020	(38,101,000)	(26,899,096)	$ 1,000	153,000	1,019,000		(39,274,000)	(26,899,815)		$ 719
Beginning Balance ,Shares at Jul. 20, 2020
Beginning Balance ,Value at Jul. 20, 2020
Issuance of Series C Redeemable Convertible Preferred Stock ,Shares										7,187,500
Issuance of ordinary shares to Sponsor		25,000				24,281				$ 719
Issuance of ordinary shares to Sponsor, Shares										7,187,500
Forfeiture of Class B ordinary shares						94				$ (94)
Forfeiture of Class B ordinary shares, Shares										(937,500)
Remeasurement adjustment on Class A ordinary shares subject to possible redemption		(26,146,752)				(24,375)		(26,122,377)
Net income (loss)		(3,294,265)						(3,294,265)
Ending Balance ,Shares at Dec. 31, 2020									32,865,949
Ending Balance ,Value at Dec. 31, 2020									$ 34,372,000
Ending Balance ,Shares at Dec. 31, 2020			7,134,668							6,250,000
Ending Balance ,Value at Dec. 31, 2020	(62,260,000)	(29,416,017)	$ 1,000	153,000	1,079,000	94	(63,493,000)	(29,416,736)		$ 625
Ending Balance ,Value at Dec. 31, 2020								(29,416,642)
Net income (loss)		9,238,963						9,238,963
Ending Balance ,Shares at Mar. 31, 2021										6,250,000
Ending Balance ,Value at Mar. 31, 2021		(20,177,054)				94		(20,177,773)		$ 625
Beginning Balance ,Shares at Dec. 31, 2020									32,865,949
Beginning Balance ,Value at Dec. 31, 2020									$ 34,372,000
Beginning Balance ,Shares at Dec. 31, 2020			7,134,668							6,250,000
Beginning Balance ,Value at Dec. 31, 2020	$ (62,260,000)	(29,416,017)	$ 1,000	153,000	1,079,000	94	(63,493,000)	(29,416,736)		$ 625
Stock options exercised ,Shares	1,685,675		1,685,675
Stock options exercised ,Value	$ 664,000				664,000
Issuance of Series C-2 Redeemable Convertible Preferred Stock, Shares									3,900,988
Issuance of Series C-2 Redeemable Convertible Preferred Stock, Value									$ 29,516,000
Warrants exercised, Shares			305,611						2,001,452
Warrants exercised, Value				(153,000)	153,000				$ 26,185,000
Stock-based compensation expense	620,000				620,000
Net income (loss)	(296,685,000)	(1,475,461)					(296,685,000)
Ending Balance ,Shares at Sep. 30, 2021									38,768,389
Ending Balance ,Value at Sep. 30, 2021									$ 90,073,000
Ending Balance ,Shares at Sep. 30, 2021			9,125,954							6,250,000
Ending Balance ,Value at Sep. 30, 2021	(357,661,000)	(30,891,478)	$ 1,000		2,516,000	94	(360,178,000)	(30,892,197)		$ 625
Beginning Balance ,Shares at Mar. 31, 2021										6,250,000
Beginning Balance ,Value at Mar. 31, 2021		(20,177,054)				94		(20,177,773)		$ 625
Net income (loss)		(6,784,606)						(6,784,606)
Ending Balance ,Shares at Jun. 30, 2021									36,809,092
Ending Balance ,Value at Jun. 30, 2021									$ 64,257,000
Ending Balance ,Shares at Jun. 30, 2021			8,784,265							6,250,000
Ending Balance ,Value at Jun. 30, 2021	(306,606,000)	(26,961,660)	$ 1,000	153,000	2,093,000	94	(308,853,000)	(26,962,379)		$ 625
Stock options exercised ,Shares			36,789
Stock options exercised ,Value	10,000				10,000
Warrants exercised, Shares			304,900						1,959,297
Warrants exercised, Value				$ (153,000)	153,000				$ 25,816,000
Stock-based compensation expense	260,000				260,000
Net income (loss)	(51,325,000)	(3,929,818)					(51,325,000)	(3,929,818)
Ending Balance ,Shares at Sep. 30, 2021									38,768,389
Ending Balance ,Value at Sep. 30, 2021									$ 90,073,000
Ending Balance ,Shares at Sep. 30, 2021			9,125,954							6,250,000
Ending Balance ,Value at Sep. 30, 2021	$ (357,661,000)	$ (30,891,478)	$ 1,000		$ 2,516,000	$ 94	$ (360,178,000)	$ (30,892,197)		$ 625

Condensed Statements of Redee_2

Condensed Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical)	Oct. 31, 2020shares
ACON S2 Acquisition Corp [Member] | Common Class B [Member]
Number of shares subject to forfeiture.	937,500

Condensed Statements of Cash Fl

Condensed Statements of Cash Flows - USD ($)	2 Months Ended	3 Months Ended		5 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss		$ (51,325,000)	$ (2,771,000)		$ (296,685,000)	$ (6,200,000)	$ (30,419,000)	$ (11,467,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation					404,000	306,000	436,000	260,000
Non-cash interest expense					1,495,000	65,000	91,000	976,000
Stock-based compensation expense					620,000	251,000	310,000	175,000
(Gain) loss on extinguishment of debt					(948,000)	62,000	62,000	116,000
General and administrative expenses paid by Sponsor in exchange for issuance of Class B ordinary shares	$ 16,000
Change in fair value of warrant liabilities		2,949,000	(24,000)		17,753,000	(78,000)	1,296,000	341,000
Change in fair value of derivative liabilities					248,691,000	(5,849,000)	11,532,000	19,000
Expenses paid by sponsor in exchange for working capital loan					361,751
Changes in operating assets and liabilities:
Grant receivable								423,000
Prepaid expenses and other current assets					(5,713,000)	161,000	(135,000)	(499,000)
Accounts payable					2,441,000	(534,000)	(221,000)	521,000
Accrued and other current liabilities					2,195,000	153,000	352,000	1,122,000
Customer deposits							51,000	1,338,000
Other non-current liabilities					1,404,000	(446,000)
Net cash used in operating activities					(28,343,000)	(12,109,000)	(16,645,000)	(6,675,000)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment					(288,000)	(464,000)	(502,000)	(851,000)
Net cash used in investing activities					(288,000)	(464,000)	(502,000)	(851,000)
CASH FLOWS FROM FINANCING ACTIVITIES:
Borrowings on notes payable							4,936,000
Principal payments on notes payable					(584,000)	(150,000)	(221,000)	(262,000)
Proceeds from sale of redeemable convertible preferred stock, net of issuance costs					11,461,000			19,788,000
Borrowing on notes payable, net of debt issuance cost					20,000,000	4,936,000		2,722,000
Proceeds from stock options exercised					664,000	6,000	7,000	6,000
Proceeds from warrants exercised					7
Net cash provided by financing activities					31,548,000	4,792,000	4,722,000	22,254,000
NET CHANGE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH					2,917,000	(7,781,000)	(12,425,000)	14,728,000
CASH, CASH EQUIVALENTS AND RESTRICTED CASH, BEGINNING OF PERIOD					6,394,000	18,819,000	18,819,000	4,091,000
CASH, CASH EQUIVALENTS AND RESTRICTED CASH, END OF PERIOD	11,038,000	9,311,000	11,038,000	$ 6,394,000	9,311,000	11,038,000	6,394,000	18,819,000
SUPPLEMENTAL DISCLOSURE OF CASHFLOW INFORMATION:
Operating expenses paid by Sponsor included in working capital loan					361,751
Offering costs included in accounts payable	5,000
Remeasurement adjustment on Class A ordinary shares subject to possible redemption	26,146,752
Cash paid during the year for:
Interest					237,000	62,000	111,000	38,000
Non-cash investing and financing transactions:
Property and equipment purchases financed with term loan						52,000	52,000	79,000
PPP loan forgiven					948
Non-cash extinguishment of derivative liabilities upon sale of Series C-2 redeemable convertible preferred stock, net of amount allocated to warrants					18,055,000
Non-cash extinguishment of warrant liabilities upon exercise of Series B and Series C-2 redeemable convertible preferred stock warrants					26,178,000
Purchase of property and equipment included in accounts payable and accrued and other current liabilities					343,000	8,000	55,000	87,000
Cash and cash equivalents	9,286,000	8,019,000	9,286,000	4,901,000	8,019,000	9,286,000	4,901,000	18,290,000
Restricted cash, current	1,217,000	1,217,000	1,217,000	1,167,000	1,217,000	1,217,000	1,167,000
Restricted cash, non-current	535,000	75,000	535,000	326,000	75,000	535,000	326,000	529,000
Total cash, cash equivalents and restricted cash shown in the statements of cash flows	11,038,000	9,311,000	11,038,000	6,394,000	9,311,000	11,038,000	6,394,000	18,819,000
ACON S2 Acquisition Corp [Member]
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	(777,344)	(3,929,818)		(3,294,265)	(1,475,461)
Adjustments to reconcile net loss to net cash used in operating activities:
General and administrative expenses paid by Sponsor in exchange for issuance of Class B ordinary shares				16,000
Gain on marketable securities (net) and dividends held in Trust Account		(4,925)		(4,454)	(12,393)
Change in fair value of warrant liabilities		2,232,690		1,854,400	(1,137,350)
Financing costs—derivative warrant liabilities	735,490			735,490
Changes in operating assets and liabilities:
Prepaid expenses and other current assets				(352,963)
Prepaid expenses	(420,591)				152,036
Accounts payable	406,145				222,866
Accrued expenses	3,500			29,107	1,329,655
Accrued expenses - related party	10,000			40,000	90,000
Net cash used in operating activities	(26,800)			(976,685)	(468,896)
CASH FLOWS FROM INVESTING ACTIVITIES:
Cash deposited in Trust Account	(250,000,000)			(250,000,000)
Net cash used in investing activities	(250,000,000)			(250,000,000)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from note payable to related party	25,000			25,000
Repayment of note payable to related party	(111,542)			(111,542)
Proceeds received from initial public offering, gross	250,000,000			250,000,000
Proceeds received from private placement	7,000,000			7,000,000
Offering costs paid	(5,140,200)			(5,466,700)
Net cash provided by financing activities	251,773,258			251,446,758
NET CHANGE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	1,746,458			470,073	(468,896)
CASH, CASH EQUIVALENTS AND RESTRICTED CASH, BEGINNING OF PERIOD					470,073
CASH, CASH EQUIVALENTS AND RESTRICTED CASH, END OF PERIOD	1,746,458	1,177	1,746,458	470,073	1,177	1,746,458	470,073
SUPPLEMENTAL DISCLOSURE OF CASHFLOW INFORMATION:
Offering costs paid by Sponsor in exchange for issuance of Class B ordinary shares	9,000			9,000
Offering costs included in accrued expenses	391,500			70,000
Offering costs included in note payable—related party	86,542			86,542
Deferred underwriting commissions	8,750,000			8,750,000
Remeasurement adjustment on Class A ordinary shares subject to possible redemption	(26,146,752)
Remeasurement adjustment on Class A ordinary shares subject to possible redemption				26,146,752
Forfeiture of Class B ordinary shares				94
Non-cash investing and financing transactions:
Total cash, cash equivalents and restricted cash shown in the statements of cash flows	$ 1,746,458	$ 1,177	$ 1,746,458	$ 470,073	$ 1,177	$ 1,746,458	$ 470,073
Series B Redeemable Convertible Preferred Stock [Member]
Non-cash investing and financing transactions:
Conversion of convertible notes payable and accrued interest to Series B Redeemable Convertible Preferred Stock								$ 9,845,000

Description of Business and Sum

Description of Business and Summary of Significant Accounting Policies	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business and Summary of Significant Accounting Policies	1. DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Description of Business ESS Tech, Inc. (the “Company”) was founded as Energy Storage Systems, LLC in Portland, Oregon in 2011. The Company converted to a Delaware corporation and changed its name to ESS Tech, Inc. in 2014. The Company does not have any subsidiaries. The Company develops long-duration iron flow batteries for commercial and utility-scale energy storage applications requiring four or more hours of flexible energy capacity. The Company’s products are designed for a 25-year The Company is in the research and development phase. Its product is still being developed and does not yet meet standard specifications to be sold (“Commercially Available”). On October 8, 2021 (the “Closing Date”), ESS Tech, Inc., a Delaware corporation (“New ESS”), formerly known as ACON S2 Acquisition Corp., a Delaware corporation (“STWO”), consummated the previously announced merger pursuant to that certain Agreement and Plan of Merger, dated May 6, 2021 (the “Merger Agreement”), by and among STWO, SCharge Merger Sub, Inc., a Delaware corporation and wholly owned direct subsidiary of STWO (“Merger Sub”), and the Company following the approval at a special meeting of the stockholders of STWO held on October 5, 2021. Pursuant to the terms of the Merger Agreement, STWO deregistered by way of continuation under the Cayman Islands Companies Act (2021 Revision) and registered as a corporation in the State of Delaware under Part XII of the Delaware General Corporation Law, and a business combination between STWO and the Company was effected through the merger of Merger Sub with and into the Company, with the Company surviving as a wholly owned subsidiary of STWO (together with the other transactions described in the Merger Agreement, the “Merger”). On the Closing Date, STWO changed its name from “ACON S2 Acquisition Corp” to “ESS Tech, Inc.”, and its shares and warrants commenced trading on the New York Stock Exchange under the new ticker symbols “GWH” and “GWH.W”, respectively. As a result of its initial public offering of Class A ordinary shares in September 2020, STWO held approximately $250,000 thousand in a trust account (the “Trust Account”). In connection with the Merger, STWO stockholders holding 20,754,719 shares of STWO’s Class A ordinary shares exercised their right to redeem such shares. As a result, approximately $207,500 thousand of funds were withdrawn from the Trust Account to fund participant share redemptions. Also, in connection with the Merger, on the Closing Date, STWO issued and sold an aggregate of 25,000,000 shares of STWO Class A ordinary shares for a purchase price of $10.00 per share and an aggregate purchase price of $250,000 thousand pursuant to subscription agreements, dated as of May 6, 2021, with certain accredited investors, in a private investment in public equity offering (“PIPE”). Cash received by the Company from the consummation of the Merger including the PIPE and the remaining balance in the STWO Trust Account after estimated expenses approximated $246,000 thousand. Basis of presentation The accompanying unaudited condensed financial statements have been prepared in accordance with generally accepted accounting principles in the United States (“U.S. GAAP”). Certain information and note disclosures normally included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted. Accordingly, these unaudited condensed financial statements should be read in conjunction with the audited financial statements and accompanying notes for the year ended December 31, 2020. The condensed balance sheet as of December 31, 2020, included herein was derived from the audited financial statements of the Company as of that date. The unaudited condensed financial statements, in the opinion of management, reflect all adjustments necessary to present fairly the Company’s financial position as of September 30, 2021, and the Company’s results of operations and comprehensive loss, redeemable convertible preferred stock and stockholders’ deficit activities for the three and nine months ended September 30, 2021, and 2020, and the cash flows for the nine months ended September 30, 2021, and 2020. The results for the three and nine months ended September 30, 2021 are not necessarily indicative of the results to be expected for the year ending December 31, 2021, any interim period or for any other future year. Emerging Growth Company Section 102(b)(1) of the Jumpstart Our Business Startups Act of 2012 (the “JOBS Act”) exempts emerging growth companies from being required to comply with new or revised financial accounting standards until private companies (that is, those that have not had a Securities Act registration statement declared effective or do not have a class of securities registered under the Securities Exchange Act of 1934, as amended) are required to comply with the new or revised financial accounting standards. The JOBS Act provides that an emerging growth company can elect to opt out of the extended transition period and comply with the requirements that apply to non-emerging This may make comparison of the Company’s financial statements with another public company that is neither an emerging growth company nor an emerging growth company that has opted out of using the extended transition period difficult or impossible because of the potential differences in accounting standards used. Liquidity and Going concern In connection with preparing financial statements for each interim and annual reporting period, the Company evaluates whether there are conditions or events, considered in the aggregate, that raise substantial doubt about its ability to continue as a going concern within one year after the date on which the financial statements are issued in accordance with FASB Accounting Standards Update No. 2014-15, Presentation of Financial Statements—Going Concern (Subtopic 205-40): 2014-15”) The Company’s financial statements have been prepared assuming that it will continue as a going concern , As of September 30, 2021, the Company had approximately $8,019 thousand in cash and cash equivalents. As also reflected in the condensed financial statements, the Company had an accumulated deficit on September 30, 2021, and December 31, 2020, and had net losses and net cash used in operating activities for the reporting periods then ended. These factors, coupled with the available cash on hand as of September 30, 2021, and compared to management’s operating plan, raised substantial doubt about the Company’s ability to continue as a going concern. However, as discussed in Note 10 Subsequent Events, the Company effected the close of the Merger with STWO on October 8, 2021, which contributed approximately $246,000 thousand, from the transaction. The Company has capitalized $3,471 thousand of transaction costs as of September 30, 2021. The Company believes that the net proceeds from the Merger plus its cash and cash equivalent balance at September 30, 2021 provide it with sufficient resources to continue as a going concern for at least the next 12 months from the date the condensed financial statements are issued. Segment information The Company has determined that its Chief Executive Officer (“CEO”) is its chief operating decision maker (“CODM”). The CEO reviews financial information presented for purposes of assessing performance and making decisions on how to allocate resources. The Company has determined that it operates in a single reportable segment. All the Company’s operations and long-lived assets were attributable to operations in the United States as of September 30, 2021 and December 31, 2020. Use of Estimates The preparation of the financial statements in conformity with U.S. GAAP requires management to make estimates, judgments and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent liabilities as of the date of the financial statements and the reported amounts of expenses during the reporting periods. Such estimates relate to, among others, the useful lives and assessment of recoverability of property and equipment, deferred tax assets valuation, determination of the fair value of the Company’s Bridge Loan, common and preferred stock, warrant liabilities, Series C-2 Significant Risks and Uncertainties The Company is subject to those risks common in the technology industry and also those risks common to early-stage companies including, but not limited to, the possibility of not being able to successfully develop or market its products, technological obsolescence, competition, dependence on key personnel and key external alliances, the successful protection of its proprietary technologies, compliance with government regulations, and the possibility of not being able to obtain additional financing when needed. COVID-19 Concentration of Supply Chain Risk The Company uses various raw materials and components that are critical to the future manufacturing of its energy storage solutions. Suppliers must undergo a qualification process, which typically requires four to twelve months to complete. The Company does not know whether it will be able to maintain long-term supply relationships with its critical suppliers, or secure new long-term supply relationships on terms that will allow it to achieve its objectives, if at all. A supplier’s failure to develop and supply components in a timely manner or to supply components that meet the Company’s quality, quantity, cost requirements or technical specifications, or the Company’s inability to source these components from alternative providers on a timely basis or on terms acceptable to the Company could each harm the Company’s ability to manufacture its energy storage solutions at the time when its products are commercially ready. In addition, to the extent the processes that the Company’s suppliers use to manufacture components are proprietary, the Company may be unable to obtain comparable components from alternative suppliers, all of which could harm the Company’s business prospects, results of operations and financial condition. Concentration of Credit Risk Financial instruments that potentially subject the Company to concentration of credit risk consist of cash and cash equivalents and restricted cash. The Company’s cash and cash equivalents include cash in bank accounts and a money market account. The Company’s restricted cash includes a certificate of deposit and performance and payment bond. Deposits held with banks may exceed the amount of insurance provided on such deposits. Significant Accounting Policies There have been no material changes in the significant accounting policies described in our Audited Financial Statements as of and for the year ended December 31, 2020. Accounting Standards Pending Adoption There have been no material changes in the accounting standards pending adoption described in the Company’s audited financial statements for the year ended December 31, 2020.	1. DESCRIPTION OF BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Description of Business— The Company develops long-duration iron flow batteries for commercial and utility-scale energy storage applications requiring four or more hours of flexible energy capacity. The Company’s products are designed for a 25-year operating life without performance degradation, with minimal annual operations and maintenance requirements. The Company is in the research and development phase. Its product is still being developed and has not met standard specifications to be sold (“Commercially Available”). Basis of Presentation Emerging Growth Company Section 102(b)(1) of the Jumpstart Our Business Startups Act of 2012 (the “JOBS Act”) exempts emerging growth companies from being required to comply with new or revised financial accounting standards until private companies (that is, those that have not had a Securities Act registration statement declared effective or do not have a class of securities registered under the Securities Exchange Act of 1934, as amended) are required to comply with the new or revised financial accounting standards. The JOBS Act provides that an emerging growth company can elect to opt out of the extended transition period and comply with the requirements that apply to non-emerging growth companies but any such election to opt out is irrevocable. The Company is keeping its election to be able to defer the adoption of a new or revised standard at the time private companies are required to adopt the new or revised standard. This may make comparison of the Company’s financial statement with another public company that is neither an emerging growth company nor an emerging growth company that has opted out of using the extended transition period difficult or impossible because of the potential differences in accounting standards used. Liquidity and Going concern In connection with preparing financial statements for each annual reporting period, the Company evaluates whether there are conditions or events, considered in the aggregate, that raise substantial doubt about its ability to continue as a going concern within one year after the date on which the financial statements are issued in accordance with FASB Accounting Standards Update No. 2014-15, Presentation of Financial Statements—Going Concern (Subtopic 205-40): Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern (“ASU 2014-15”) The Company’s financial statements have been prepared assuming that it will continue as a going concern , As of December 31, 2020, the Company had $4,901 thousand of cash and cash equivalents. As reflected also in the financial statements, the Company had an accumulated deficit on December 31, 2020, and has had recurring net losses and net cash used in operating activities for the reporting period then ended. These factors coupled with the available cash on hand compared to management’s operating plan raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date the financial statements are issued. The financial statements do not include any adjustments to reflect the possible future effects on the recoverability and classification of assets or the amounts and classification of liabilities that may result in the Company not being able to continue as a going concern, other than the reclassification of notes payable, non-current and the related debt issuance costs to current liabilities. The principal payments and accrued interest due under the notes payable agreements have been classified as current liabilities as of December 31, 2020 due to the considerations discussed above and the assessment that the material adverse change clause under the notes payable agreements is not within the Company’s control. The Company has not been notified of an event of default by the Lenders as of the date of issuance of these financial statements. The Company’s plan is to seek additional funding through the completion of a business combination with ACON S2 Acquisition Corp. (“ACON”) (see Note 17). At this time, the Company is focused on completing the business combination with ACON, which is subject to the approval of the shareholders of both companies, regulatory approval from the Securities and Exchange Commission and other customary closing conditions, and is limited in its efforts to raise additional capital from secondary sources. If the Company is unable to complete the business combination with ACON, then the Company would have to pursue a secondary course of action to seek additional capital through other debt and equity financings. If the Company is unable to raise sufficient additional capital, through future debt or equity financings or through strategic and collaborative ventures with third parties, then the Company will not have sufficient cash flows and liquidity to fund its planned business operations for the year following the date the audited financial statements were available to be issued, as of June 16, 2021. There can be no assurances that the Company will be able to complete the business combination, or that in the event that the business combination does not take place, the Company will be able to secure alternate forms of financing at terms that are acceptable to management, if at all. If the Company is unable to raise additional capital when required or on acceptable terms, or unable to continue as a going concern, then the Company may be required to scale back or discontinue the development of its product, reduce headcount, file for bankruptcy, reorganize, merge with another entity, cease operations, and/or stockholders may lose all or part of their investment in the Company’s stock. Risks and Uncertainties In March 2020, the World Health Organization declared the outbreak of a novel corona virus as a pandemic. The pandemic has reached every region of the world and has resulted in widespread adverse impacts on the global economy. In response, the Company has modified certain business and workforce practices (including discontinuing all non-essential business travel, implementing a temporary work-from-home policy for employees who can execute their work remotely and encouraging employees to adhere to local and regional social distancing, more stringent hygiene and cleaning protocols across the Company’s facilities and operations and self-quarantining recommendations) to conform to government restrictions and best practices encouraged by governmental and regulatory authorities. However, the quarantine of personnel or the inability to access the Company’s facilities or customer sites could adversely affect the Company’s operations. As of the date of this report, the Company’s efforts to respond to the challenges presented by the conditions described above have allowed the Company to minimize the impacts to its business. Segment information single All the Company’s operations and long-lived assets were attributable to operations in the United States as of December 31, 2020 and 2019. Use of Estimates Concentration of Supply Chain Risk Concentration of Credit Risk Significant Accounting Policies Net loss per share Cash and Cash Equivalents Restricted Cash Grants Receivable The portion of such funding that the Company may be required to repay in certain circumstances is recorded in accrued and other liabilities and was $186 thousand and $0 for the years ended December 31, 2020 and 2019, respectively. The portion of such funding that the Company is not required to repay is recorded as a reduction of research and development costs and was $40 thousand and $20 thousand for the years ended December 31, 2020 and 2019, respectively. Grants receivable balance was $0 as of December 31, 2020 and 2019. Property and Equipment three The Company evaluates the recoverability of property and equipment for possible impairment whenever events or circumstances indicate that the carrying amount of such assets may not be recoverable. The Company assesses the alternative use of an asset, the condition of the asset and the current market demand to determine if an asset is impaired. No impairment was recognized during the years ended December 31, 2020 and 2019. Debt Issuance Costs Revenue Recognition Revenue from Contracts with Customers (Topic 606) Sales and Marketing Research and Development General and Administrative Stock-Based Compensation Compensation – Stock Compensation (“ASC 718”) The Company measures compensation expense for all stock-based payment awards for stock options granted to employees and non-employees based on the estimated fair values on the date of the grant. The fair value of each stock option granted is estimated using the Black-Scholes Merton option-pricing model using the single-option award approach. The following assumptions are used in the Black-Scholes Merton option-pricing model: Risk-Free Interest Rate Expected Volatility Expected Term Dividend Yield In accordance with ASU 2016-09, the Company may account for forfeitures as they occur or use estimated forfeitures. The Company elected to use actual forfeitures. The share-based compensation expense is recognized using a straight-line basis over the requisite service periods of the awards. The requisite service period is generally the vesting period of such options, and the stock-based compensation expense is presented as a component of operating expenses within the statements of operations. The Company recognizes all excess tax benefits and deficiencies for share-based awards as an income tax expense or benefit in the statements of operations. Excess tax benefits are classified with other income tax in the cash flows as an operating activity. The Company accounts for stock-based compensation for nonemployees in accordance with ASC 505 “ Equity Based Payments to Nonemployees” (“ASC 505”) Income Taxes ASC 740, Accounting for Income Taxes, The Company recognizes accrued interest and penalties related to unrecognized tax benefits as income tax expense. No amounts were accrued for the payment of interest and penalties as of December 31, 2020 and 2019 as the Company is currently not aware of any issues under review that could result in significant payments, accruals, or material deviation from its position. Fair Value Fair Value Measurements ASC 820 establishes a hierarchy for inputs used in measuring fair value that maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that observable inputs be used when available. Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company’s assumptions about what market participants would use in pricing the asset or liability based on the best information available in the circumstances. The hierarchy is broken down into three levels based on the reliability of inputs as follows: Level 1: Level 2: Level 3: Because of the uncertainties inherent in the valuation of assets or liabilities for which there are no observable inputs, those estimated fair values may differ significantly from the values that may have been used had a ready market for the assets or liabilities existed. Recently Issued Accounting Standards In February 2016, the Financial Accounting Standards Board (“FASB”) issued No. ASU 2016-02, Lease s (Topic 842) , Leases (Topic 842) In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes In August 2020, the FASB issued ASU 2020-06 , Debt with Conversion and Other Options (Subtopic 470-20) Contracts in Entity’s Own Equity (Subtopic 815-40) Derivatives and Hedging Derivatives and Hedging—Contracts in Entity’s Own Equity

Description of Organization, Bu

Description of Organization, Business Operations and Basis of Presentation	5 Months Ended	9 Months Ended
	Dec. 31, 2020	Sep. 30, 2021
ACON S2 Acquisition Corp [Member]
Description Of Organization Business Operations And Basis Of Presentation [Line Items]
Description of Organization, Business Operations and Basis of Presentation	Note 1—Description of Organization, Business Operations and Basis of Presentation ESS Tech, Inc., formerly known as ACON S2 Acquisition Corp. (the “Company”), is a blank check company incorporated as a Cayman Islands exempted company on July 21, 2020. The Company was incorporated for the purpose of effecting a merger, share exchange, asset acquisition, share purchase, reorganization or similar business combination with one or more businesses that the Company has not yet identified (“Business Combination”). While the Company may pursue a Business Combination opportunity in any business, industry, sector or geographical location, management intends to initially focus the search on identifying a prospective target business that employs a strategic approach to sustainability; that is, a business whose pursuit of sustainability — environmental, social and/or economic — is core to driving its performance and success. The Company is an “emerging growth company,” as defined in Section 2(a) of the Securities Act of 1933, as amended (the “Securities Act”), as modified by the Jumpstart our Business Startups Act of 2012 (the “JOBS Act”). As of December 31, 2020, the Company had not yet commenced operations. All activity for the period from July 21, 2020 (inception) through December 31, 2020 relates to the Company’s formation and the initial public offering (the “Initial Public Offering”), which is described below , and, since the closing of the Initial Public Offering, a search for a business combination candidate. The Company will not generate any operating revenues until after the completion of its initial Business Combination, at the earliest. The Company will generate non-operating The Company’s sponsor is ACON S2 Sponsor, L.L.C., a Delaware limited liability company (“Sponsor”). The registration statement for the Company’s Initial Public Offering was declared effective on September 16, 2020. On September 21, 2020, the Company consummated its Initial Public Offering of 25,000,000 units (the “Units” and, with respect to the Class A ordinary shares included in the Units being offered, the “Public Shares”), at $10.00 per Unit, generating gross proceeds of $250.0 million, and incurring offering costs of approximately $14.4 million, inclusive of approximately $8.8 million in deferred underwriting commissions (Note 7). The underwriters were granted a 45-day option from Simultaneously with the closing of the Initial Public Offering, the Company consummated the private placement (“Private Placement”) of 4,666,667 warrants (each, a “Private Placement Warrant” and collectively, the “Private Placement Warrants”), at a price of $1.50 per Private Placement Warrant with our Sponsor, generating gross proceeds of $7.0 million (Note 5). Upon the closing of the Initial Public Offering and the Private Placement, $250.0 million ($10.00 per Unit) of the net proceeds of the sale of the Units in the Initial Public Offering and the Private Placement were placed in a trust account (“Trust Account”) with Continental Stock Transfer & Trust Company acting as trustee and invested in United States “government securities” within the meaning of Section 2(a)(16) of the Investment Company Act having a maturity of 185 days or less or in money market funds meeting certain conditions under Rule 2a-7 promulgated The Company’s management has broad discretion with respect to the specific application of the net proceeds of its Initial Public Offering and the sale of the Private Placement Warrants, although substantially all of the net proceeds are intended to be applied generally toward consummating a Business Combination. The Company’s initial Business Combination must be with one or more operating businesses or assets with a fair market value equal to at least 80% of the net assets held in the Trust Account (as defined below) (excluding the deferred underwriting commissions and taxes payable on the interest earned on the trust account) at the time the Company signs a definitive agreement in connection with the initial Business Combination. However, the Company will only complete a Business Combination if the post-transaction company owns or acquires 50% or more of the outstanding voting securities of the target or otherwise acquires a controlling interest in the target sufficient for it not to be required to register as an investment company under the Investment Company Act 1940, as amended, or the Investment Company Act. The Company will provide its holders of the Public Shares (the “Public Shareholders”) with the opportunity to redeem all or a portion of their Public Shares upon the completion of a Business Combination either (i) in connection with a shareholder meeting called to approve the Business Combination or (ii) by means of a tender offer. The decision as to whether the Company will seek shareholder approval of a Business Combination or conduct a tender offer will be made by the Company, solely in its discretion. The Public Shareholders will be entitled to redeem their Public Shares for a pro rata portion of the amount then in the Trust Account (initially anticipated to be $10.00 per share, plus any pro rata interest earned on the funds held in the Trust Account and not previously released to the Company to pay its tax obligations). The per-share amount Notwithstanding the foregoing, the Company’s Amended and Restated Memorandum and Articles of Association provide that a public shareholder, together with any affiliate of such shareholder or any other person with whom such shareholder is acting in concert or as a “group” (as defined under Section 13 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”)), is restricted from redeeming its shares with respect to more than an aggregate of 15% or more of the Class A ordinary shares sold in the Initial Public Offering, without the prior consent of the Company. The Company’s Sponsor, executive officers and directors agreed not to propose an amendment to the Company’s Amended and Restated Memorandum and Articles of Association that would affect the substance or timing of the Company’s obligation to provide for the redemption of its Public Shares in connection with a Business Combination or to redeem 100% of its Public Shares if the Company does not complete a Business Combination, unless the Company provides the Public Shareholders with the opportunity to redeem their Class A ordinary shares in conjunction with any such amendment. If the Company is unable to complete a Business Combination within 24 months from the closing of the Initial Public Offering, or September 21, 2022 (the “Combination Period”), the Company will (i) cease all operations except for the purpose of winding up; (ii) as promptly as reasonably possible but not more than ten (10) business days thereafter, redeem the Public Shares, at a per-share price, The Initial Shareholders agreed to waive their liquidation rights with respect to the Founder Shares if the Company fails to complete a Business Combination within the Combination Period. However, if the Initial Shareholders should acquire Public Shares in or after the Initial Public Offering, they will be entitled to liquidating distributions from the Trust Account with respect to such Public Shares if the Company fails to complete a Business Combination within the Combination Period. The underwriters have agreed to waive their rights to their deferred underwriting commission (see Note 7) held in the Trust Account in the event the Company does not complete a Business Combination within in the Combination Period and, in such event, such amounts will be included with the funds held in the Trust Account that will be available to fund the redemption of the Company’s Public Shares. In the event of such distribution, it is possible that the per share value of the residual assets remaining available for distribution (including Trust Account assets) will be only $10.00 per share initially held in the Trust Account. In order to protect the amounts held in the Trust Account, our Sponsor has agreed that it will be liable to the Company if and to the extent any claims by a third party for services rendered or products sold to the Company, or a prospective target business with which the Company has entered into a written letter of intent, confidentiality or other similar agreement or business combination agreement, reduce the amount of funds in the Trust Account to below the lesser of (i) $10.00 per Public Share and (ii) the actual amount per Public Share held in the Trust Account as of the date of the liquidation of the Trust Account, if less than $10.00 per share due to reductions in the value of the trust assets, less taxes payable, provided that such liability will not apply to any claims by a third party or prospective target business who executed a waiver of any and all rights to the monies held in the Trust Account (whether or not such waiver is enforceable) nor will it apply to any claims under the Company’s indemnity of the underwriters of the Initial Public Offering against certain liabilities, including liabilities under the Securities Act. In the event that an executed waiver is deemed to be unenforceable against a third party, our Sponsor will not be responsible to the extent of any liability for such third-party claims. The Company will seek to reduce the possibility that our Sponsor will have to indemnify the Trust Account due to claims of creditors by endeavoring to have vendors, service providers (except the Company’s independent registered public accounting firm), prospective target businesses or other entities with which the Company does business, execute agreements with the Company waiving any right, title, interest or claim of any kind in or to monies held in the Trust Account. Basis of Presentation The Company’s financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”) and include all adjustments necessary for the fair presentation of the Company’s financial position for the periods presented. As described in Note 2—Restatement of Previously Issued Financial Statements, the Company’s financial statements as of December 31, 2020 and for the period from July 21, 2020 (inception) through December 31, 2020 and as of September 30, 2020 and for the period from July 21, 2020 (inception) through September 30, 2020 as well as the balance sheet as of September 21, 2020 (the “Affected Periods”), are restated in this Annual Report on Form 10-K/A • the misapplication of accounting guidance related to the Company’s warrants in the Company’s previously issued audited and unaudited condensed financial statements for such periods. The restated financial statements are indicated as “Restated” in the audited and unaudited condensed financial statements and accompanying notes, as applicable (Amendment No. 1); and • the misapplication of accounting guidance related to the Company’s Public Shares in the Company’s previously issued audited and unaudited condensed financial statements for such periods. The restated financial statements are indicated as “Restated” in the audited and unaudited condensed financial statements and accompanying notes, as applicable. (Amendment No. 2). See Note 2—Restatement of Previously Issued Financial Statements for further discussion. Emerging Growth Company The Company is an “emerging growth company,” as defined in Section 2(a) of the Securities Act, as modified by the JOBS Act, and it may take advantage of certain exemptions from various reporting requirements that are applicable to other public companies that are not emerging growth companies including, but not limited to, not being required to comply with the auditor attestation requirements of Section 404 of the Sarbanes-Oxley Act of 2002, reduced disclosure obligations regarding executive compensation in its periodic reports and proxy statements, and exemptions from the requirements of holding a nonbinding advisory vote on executive compensation and shareholder approval of any golden parachute payments not previously approved. Further, Section 102(b)(1) of the JOBS Act exempts emerging growth companies from being required to comply with new or revised financial accounting standards until private companies (that is, those that have not had a Securities Act registration statement declared effective or do not have a class of securities registered under the Exchange Act) are required to comply with the new or revised financial accounting standards. The JOBS Act provides that an emerging growth company can elect to opt out of the extended transition period and comply with the requirements that apply to non-emerging growth companies but This may make comparison of the Company’s financial statements with another public company that is neither an emerging growth company nor an emerging growth company that has opted out of using the extended transition period difficult or impossible because of the potential differences in accounting standards used. Going Concern As of December 31, 2020, the Company had approximately $470,000 in our operating bank account, and working capital of approximately $547,000. The Company’s liquidity needs to date have been satisfied through a contribution of $25,000 from the Sponsor to cover certain of the Company’s expenses on our behalf in exchange for the issuance of the Founder Shares, the loan proceeds of $112,000 from the Sponsor pursuant to the Note (see Note 5), and the net proceeds from the consummation of the Private Placement not held in the Trust Account. The Company fully repaid the Note on September 21, 2020. In addition, in order to finance transaction costs in connection with a Business Combination, the Company’s officers, directors and Initial Shareholders may, but are not obligated to, provide the Company a working capital loan. As of December 31, 2020, there were no amounts outstanding under any Working Capital Loan. Until the consummation of a Business Combination, the Company will be using the funds not held in the Trust Account for identifying and evaluating prospective acquisition candidates, performing due diligence on prospective target businesses, paying for travel expenditures, selecting the target business to acquire, and structuring, negotiating and consummating the Business Combination. The Company will need to raise additional capital through loans or additional investments from its Sponsor, shareholders, officers, directors, or third parties. The Company’s officers, directors and Sponsor may, but are not obligated to, loan the Company funds from time to time or at any time, in whatever amount they deem reasonable in their sole discretion, to meet the Company’s working capital needs. Accordingly, the Company may not be able to obtain additional financing. If the Company is unable to raise additional capital, it may be required to take additional measures to conserve liquidity, which could include, but not necessarily be limited to, curtailing operations, suspending the pursuit of a potential transaction, and reducing overhead expenses. The Company cannot provide any assurance that new financing will be available to it on commercially acceptable terms, if at all. These conditions raise substantial doubt about the Company’s ability to continue as a going concern until the earlier of the consummation of the Business Combination or the date the Company is required to liquidate, September 22, 2022. These financial statements do not include any adjustments relating to the recovery of the recorded assets or the classification of the liabilities that might be necessary should the Company be unable to continue as a going concern. Risks and Uncertainties In March 2020, the World Health Organization declared the outbreak of a novel coronavirus (COVID-19) COVID-19 .	Note 1-Description ESS Tech, Inc., formerly known as ACON S2 Acquisition Corp. (the “Company”) was a blank check company incorporated as a Cayman Islands exempted company on July 21, 2020. The Company was incorporated for the purpose of effecting a merger, share exchange, asset acquisition, share purchase, reorganization or similar business combination with one or more businesses Business Combination. While the Company may pursue a business combination opportunity in any business, industry, sector or geographical location, management intends to initially focus the search on identifying a prospective target business that employs a strategic approach to sustainability; that is, a business whose pursuit of sustainability—environmental, social and/or economic—is core to driving its performance and success. The Company is an “emerging growth company,” as defined in Section 2(a) of the Securities Act of 1933, as amended (the “Securities Act”), as modified by the Jumpstart our Business Startups Act of 2012 (the “JOBS Act”). The Business Combination On October 8, 2021 (the “Closing Date”), the Company consummated the previously announced Merger pursuant to that certain Agreement and Plan of Merger, dated as of May 6, 2021 (as it may be amended, supplemented or otherwise modified from time to time, the “Merger Agreement”), by and among the Company, SCharge Merger Sub, Inc., a Delaware corporation and a wholly-owned direct subsidiary of the Company (“Merger Sub”), and ESS Tech Subsidiary, Inc. (formerly known as ESS Tech, Inc.), a Delaware corporation (“Legacy ESS”). The Merger Agreement and the transactions contemplated thereby were unanimously approved by the board of directors of each of the Company and Legacy ESS. In connection with the closing of the Merger (the “Closing”), (i) the Company became a Delaware Corporation (the “Domestication”) and (ii) following the Domestication, a business combination between the Company and Legacy ESS was effectuated through the merger of Merger Sub with and into Legacy ESS, with Legacy ESS continuing as the surviving company and as a wholly-owned subsidiary of the Company. On the Closing Date, the Company changed its name from ACON S2 Acquisition Corp. to “ESS Tech, Inc.” The Domestication, the Merger and the other transactions contemplated by the Merger Agreement are hereinafter referred to as the “Business Combination”. In accordance with the terms and subject to the conditions of the Merger Agreement, each share of common stock of Legacy ESS, par value $0.0001 per share (“Legacy ESS Common Stock”), was converted into the right to receive a number of shares of common stock, par value $0.0001 per share, of the Company (“Common Stock”) based on the adjusted equity value of Legacy ESS, as described in the Merger Agreement, at an exchange ratio of 1.47110014425, resulting in an aggregate of 99,562,793 shares of Common Stock being issued to Legacy ESS stockholders. Additionally, in the event that the volume weighted average price of the Common Stock exceeds certain price thresholds for sustained periods of time or there is a change of control where the per share consideration paid in the transaction exceeds certain thresholds, up to 15,675,002 additional shares of Common Stock may be issued to the parties that were holders of Legacy ESS Common Stock immediately prior to the Closing. No fractional shares of Common Stock were issued upon the exchange of Legacy ESS Common Stock. Any fractional shares were rounded down to the nearest whole share of Common Stock, resulting in an aggregate total of $311.03 cash payments by the Company made to Legacy ESS stockholders in lieu of fractional shares. In connection with the Closing, the Company issued and sold an aggregate of 25,000,000 shares of Common Stock for a purchase price of $10.00 per share and an aggregate purchase price of $250.0 million pursuant to previously announced subscription agreements (the “PIPE Subscription Agreements”) with certain accredited investors (the “PIPE Investment”). In connection with the Closing, the Company’s shareholders holding 20,754,719 shares of Common Stock exercised their right to redeem such shares. As a result, approximately $207,547,190 of funds was withdrawn from the Company’s trust account (the “Trust Account”) to fund participant share redemptions. Also in connection with the Closing, 583,333 private placement warrants held by the Sponsor (as defined below) were forfeited. Of the remaining 4,083,334 private placement warrants, 3,500,000 vested at Closing, and 583,334 will vest in two equal tranches upon the occurrence of certain milestone events. See the Company’s Current Report on Form 8-K Business Prior to the Business Combination On May 6, 2021, the Company, entered into an Agreement and Plan of Merger (as it may be amended, supplemented or otherwise modified from time to time, the “Merger Agreement”), by and among the Company, SCharge Merger Sub, Inc., a Delaware corporation and a wholly-owned direct subsidiary of the Company (“Merger Sub”), and ESS Tech, Inc., a Delaware corporation. The Merger Agreement and the transactions contemplated thereby were unanimously approved by the board of directors of each of the Company and Legacy ESS. On October 8, 2021, the Company completed the business combination. See business combination described below. All activity for the period from July 21, 2020 (inception) through September 30, 2021 relates to the Company’s formation and the initial public offering (the “Initial Public Offering”), which is described below, and, since the closing of the Initial Public Offering, a search for a business combination candidate. The Company will not generate any operating revenues until after the completion of its initial business combination, at the earliest. The Company will generate non-operating The Company’s sponsor is ACON S2 Sponsor, L.L.C., a Delaware limited liability company (“Sponsor”). The registration statement for the Company’s Initial Public Offering was declared effective on September 16, 2020. On September 21, 2020, the Company consummated its Initial Public Offering of 25,000,000 units (the “Units” and, with respect to the Class A ordinary shares included in the Units being offered, the “Public Shares”), at $10.00 per Unit, generating gross proceeds of $250.0 million, and incurring offering costs of approximately $14.4 million, inclusive of approximately $8.8 million in deferred underwriting commissions (Note 7). The underwriters were granted a 45-day Simultaneously with the closing of the Initial Public Offering, the Company consummated the private placement (“Private Placement”) of 4,666,667 warrants (each, a “Private Placement Warrant” and collectively, the “Private Placement Warrants”), at a price of $1.50 per Private Placement Warrant with our Sponsor, generating gross proceeds of $7.0 million (Note 5). Upon the closing of the Initial Public Offering and the Private Placement, $250.0 million ($10.00 per Unit) of the net proceeds of the sale of the Units in the Initial Public Offering and the Private Placement were placed in a trust account (“Trust Account”) with Continental Stock Transfer & Trust Company acting as trustee and invested in United States “government securities” within the meaning of Section 2(a)(16) of the Investment Company Act having a maturity of 185 days or less or in money market funds meeting certain conditions under Rule 2a-7 While the Company’s management has broad discretion with respect to the specific application of the cash held outside of the Trust Account, substantially all of the net proceeds from the Initial Public Offering and the sale of the Private Placement Warrants, which are placed in the Trust Account, are intended to be applied generally toward completing a Business Combination. The Company’s initial business combination must be with one or more operating businesses or assets with a fair market value equal to at least 80% of the net assets held in the Trust Account (as defined below) (excluding the deferred underwriting commissions and taxes payable on the interest earned on the trust account) at the time the Company signs a definitive agreement in connection with the initial business combination. However, the Company will only complete a business combination if the post-transaction company owns or acquires 50% or more of the outstanding voting securities of the target or otherwise acquires a controlling interest in the target sufficient for it not to be required to register as an investment company under the Investment Company Act 1940, as amended, or the Investment Company Act. The Company will provide its holders of the Public Shares (the “Public Shareholders”) with the opportunity to redeem all or a portion of their Public Shares upon the completion of a business combination either (i) in connection with a shareholder meeting called to approve the business combination or (ii) by means of a tender offer. The decision as to whether the Company will seek shareholder approval of a business combination or conduct a tender offer will be made by the Company, solely in its discretion. The Public Shareholders will be entitled to redeem their Public Shares for a pro rata portion of the amount then in the Trust Account (initially anticipated to be $10.00 per share, plus any pro rata interest earned on the funds held in the Trust Account and not previously released to the Company to pay its tax obligations). The per-share In addition, the Initial Shareholders have agreed to waive their redemption rights with respect to their Founder Shares and Public Shares in connection with the completion of a business combination. In addition, the Company has agreed not to enter into a definitive agreement regarding an initial business combination without the prior consent of our Sponsor. Notwithstanding the foregoing, the Company’s Amended and Restated Memorandum and Articles of Association provide that a public shareholder, together with any affiliate of such shareholder or any other person with whom such shareholder is acting in concert or as a “group” (as defined under Section 13 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”)), is restricted from redeeming its shares with respect to more than an aggregate of 15% or more of the Class A ordinary shares sold in the Initial Public Offering, without the prior consent of the Company. The Company’s Sponsor, executive officers and directors agreed not to propose an amendment to the Company’s Amended and Restated Memorandum and Articles of Association that would affect the substance or timing of the Company’s obligation to provide for the redemption of its Public Shares in connection with a business combination or to redeem 100% of its Public Shares if the Company does not complete a business combination, unless the Company provides the Public Shareholders with the opportunity to redeem their Class A ordinary shares in conjunction with any such amendment. If the Company is unable to complete a business combination within 24 months from the closing of the Initial Public Offering, or September 21, 2022 (the “Combination Period”), the Company will (i) cease all operations except for the purpose of winding up; (ii) as promptly as reasonably possible but not more than ten (10) business days thereafter, redeem the Public Shares, at a per-share The Initial Shareholders agreed to waive their liquidation rights with respect to the Founder Shares if the Company fails to complete a business combination within the Combination Period. However, if the Initial Shareholders should acquire Public Shares in or after the Initial Public Offering, they will be entitled to liquidating distributions from the Trust Account with respect to such Public Shares if the Company fails to complete a business combination within the Combination Period. The underwriters have agreed to waive their rights to their deferred underwriting commission (see Note 7) held in the Trust Account in the event the Company does not complete a business combination within in the Combination Period and, in such event, such amounts will be included with the funds held in the Trust Account that will be available to fund the redemption of the Company’s Public Shares. In the event of such distribution, it is possible that the per share value of the residual assets remaining available for distribution (including Trust Account assets) will be only $10.00 per share initially held in the Trust Account. In order to protect the amounts held in the Trust Account, our Sponsor has agreed that it will be liable to the Company if and to the extent any claims by a third party for services rendered or products sold to the Company, or a prospective target business with which the Company has entered into a written letter of intent, confidentiality or other similar agreement or business combination agreement, reduce the amount of funds in the Trust Account to below the lesser of (i) $10.00 per Public Share and (ii) the actual amount per Public Share held in the Trust Account as of the date of the liquidation of the Trust Account, if less than $10.00 per share due to reductions in the value of the trust assets, less taxes payable, provided that such liability will not apply to any claims by a third party or prospective target business who executed a waiver of any and all rights to the monies held in the Trust Account (whether or not such waiver is enforceable) nor will it apply to any claims under the Company’s indemnity of the underwriters of the Initial Public Offering against certain liabilities, including liabilities under the Securities Act. In the event that an executed waiver is deemed to be unenforceable against a third party, our Sponsor will not be responsible to the extent of any liability for such third-party claims. The Company will seek to reduce the possibility that our Sponsor will have to indemnify the Trust Account due to claims of creditors by endeavoring to have vendors, service providers (except the Company’s independent registered public accounting firm), prospective target businesses or other entities with which the Company does business, execute agreements with the Company waiving any right, title, interest or claim of any kind in or to monies held in the Trust Account. Basis of Presentation The accompanying unaudited condensed consolidated financial statements are presented in U.S. dollars in conformity with accounting principles generally accepted in the United States of America (“GAAP”) for financial information and pursuant to the rules and regulations of the SEC. Accordingly, they do not include all of the information and footnotes required by GAAP. In the opinion of management, the unaudited condensed consolidated financial statements reflect all adjustments, which include only normal recurring adjustments necessary for the fair statement of the balances and results for the period presented. Operating results for the three and nine months ended September 30, 2021 are not necessarily indicative of the results that may be expected through December 31, 2021. Emerging Growth Company The Company is an “emerging growth company,” as defined in Section 2(a) of the Securities Act, as modified by the JOBS Act, and it may take advantage of certain exemptions from various reporting requirements that are applicable to other public companies that are not emerging growth companies including, but not limited to, not being required to comply with the auditor attestation requirements of Section 404 of the Sarbanes-Oxley Act of 2002, reduced disclosure obligations regarding executive compensation in its periodic reports and proxy statements, and exemptions from the requirements of holding a nonbinding advisory vote on executive compensation and shareholder approval of any golden parachute payments not previously approved. Further, Section 102(b)(1) of the JOBS Act exempts emerging growth companies from being required to comply with new or revised financial accounting standards until private companies (that is, those that have not had a Securities Act registration statement declared effective or do not have a class of securities registered under the Exchange Act) are required to comply with the new or revised financial accounting standards. The JOBS Act provides that an emerging growth company can elect to opt out of the extended transition period and comply with the requirements that apply to non-emerging This may make comparison of the Company’s financial statements with another public company that is neither an emerging growth company nor an emerging growth company that has opted out of using the extended transition period difficult or impossible because of the potential differences in accounting standards used. Liquidity As of September 30, 2021, we had approximately $1,000 in our operating bank account, and negative working capital of approximately $1.9 million. On October 8, 2021, the Company completed the aforementioned Business Combination and completed the PIPE Investment. Based on the foregoing, management believes that the Company will have sufficient cash on hand to meet its needs through one year from this filing. Risks and Uncertainties In March 2020, the World Health Organization declared the outbreak of a novel coronavirus (COVID-19) COVID-19

Restatement of Financial Statem

Restatement of Financial Statements	5 Months Ended	9 Months Ended
	Dec. 31, 2020	Sep. 30, 2021
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Restatement of Financial Statements		Note 2 - Restatement of Previously Issued Financial Statements In preparation of the Company’s unaudited condensed consolidated financial statements as of and for the quarterly period ended September 30, 2021, the Company concluded it should restate its previously issued financial statements to classify all Class A ordinary shares subject to possible redemption in temporary equity. In accordance with the Financial Accounting Standard Board’s (“FASB”) Accounting Standards Codification (“ASC”) Topic 480 “Distinguishing Liabilities from Equity” (“ASC 480”), paragraph 480-10-S99, In accordance with SEC Staff Accounting Bulletin No. 99, “Materiality,” and SEC Staff Accounting Bulletin No. 108, “Considering the Effects of Prior Year Misstatements when Quantifying Misstatements in Current Year Financial Statements,” the Company evaluated the corrections and has determined that the related impact was material to the previously filed financial statements that contained the error, reported in the Company’s Form 8-K filed with the SEC on September 25, 2020 (the “Post-IPO Balance Sheet”) and the Company’s Form 10-Qs for the quarterly periods ended September 30, 2020, March 31, 2021, and June 30, 2021 and the Company’s 10-K/A filed with the SEC on May 24, 2021 (the “Affected Quarterly Periods”). Therefore, the Company, in consultation with its Audit Committee, concluded that the Post-IPO Balance Sheet and the Affected Quarterly Periods should be restated to present all Class A ordinary shares subject to possible redemption as temporary equity and to recognize a remeasurement adjustment from the initial book value to redemption value at the time of its Initial Public Offering. As such, the Company is reporting these restatements to those periods in this quarterly report. The previously presented Post-IPO Balance Sheet and Affected Quarterly Periods should no longer be relied upon. Impact of the Restatement The change in the carrying value of the Class A ordinary shares subject to possible redemption in the Post-IPO Balance Sheet resulted in a decrease of approximately $5.7 million in additional paid-in-capital and an increase of approximately $26.1 million to accumulated deficit, as well as a reclassification of $31.9 million Class A ordinary shares from permanent equity to temporary equity. As of September 21, 2020 As Reported Adjustment As Restated Total assets $ 252,174,258 $ 252,174,258 Total liabilities $ 29,049,500 $ 29,049,500 Class A ordinary shares subject to possible redemption 218,124,750 31,875,250 250,000,000 Preference shares — — — Class A ordinary shares 319 (319 ) — Class B ordinary shares 719 — 719 Additional paid-in 5,747,460 (5,747,460 ) — Accumulated deficit (748,490 ) (26,127,471 ) (26,875,961 ) Total shareholders’ equity (deficit) $ 5,000,008 $ (31,875,250 ) $ (26,875,242 ) Total Liabilities, Class A Ordinary Shares Subject to Possible Redemption and Shareholders’ Equity (Deficit) $ 252,174,258 $ — $ 252,174,258 The impact of the restatement on the balance sheets and statements of shareholders’ equity for the Affected Quarterly and Annual Periods is presented below. The restatement had no impact on net income or net cash flows from operating, investing or financing activities. The tables below present the effect of the financial statement adjustments related to the restatement discussed above of the Company’s previously reported balance sheet and statements of shareholders’ equity as of September 30, 2020: As of September 30, 2020 As Reported Adjustment As Restated Total assets $ 252,167,049 $ 252,167,049 Total liabilities $ 29,066,145 $ 29,066,145 Class A ordinary shares subject to possible redemption 218,100,900 31,899,100 250,000,000 Preference shares — — — Class A ordinary shares 319 (319 ) — Class B ordinary shares 719 — 719 Additional paid-in 5,776,310 (5,776,310 ) — Accumulated deficit (777,344 ) (26,122,471 ) (26,899,815 ) Total shareholders’ equity (deficit) $ 5,000,004 $ (31,899,100 ) $ (26,899,096 ) Total Liabilities, Class A Ordinary Shares Subject to Possible Redemption and Shareholders’ Equity (Deficit) $ 252,167,049 $ — $ 252,167,049 Statement of changes in Stockholders’ equity As Previously Adjustment As Restated Sale of units in initial public offering, gross $ 237,500,000 $ (237,500,000 ) $ — Offering costs $ (13,646,752 ) 13,646,752 — Remeasurement of Class A ordinary shares subject to possible redemption — (26,146,752 ) (26,146,752 ) Shares subject to possible redemption 218,100,900 (218,100,900 ) — The tables below present the effect of the financial statement adjustments related to the restatement discussed above of the Company’s previously reported balance sheet and statement of shareholders’ equity as of December 31, 2020: As of December 31, 2020 As Reported Adjustment As Restated Total assets $ 250,827,490 $ 250,827,490 Total liabilities $ 30,243,507 $ 30,243,507 Class A ordinary shares subject to possible redemption 215,583,980 34,416,020 250,000,000 Preference shares — — — Class A ordinary shares 344 (344 ) — Class B ordinary shares 625 — 625 Additional paid-in 8,293,299 (8,293,299 ) — Accumulated deficit (3,294,265 ) (26,122,377 ) (29,416,642 ) Total shareholders’ equity (deficit) $ 5,000,003 $ (34,416,020 ) $ (29,416,017 ) Total Liabilities, Class A Ordinary Shares Subject to Possible Redemption and Shareholders’ Equity (Deficit) $ 250,827,490 $ — $ 250,827,490 Statement of changes in Stockholders’ equity As Previously Adjustment As Restated Sale of units in initial public offering, gross $ 237,500,000 $ (237,500,000 ) $ — Offering costs $ (13,646,752 ) 13,646,752 — Remeasurement of Class A ordinary shares subject to possible redemption — (26,146,752 ) (26,146,752 ) Shares subject to possible redemption (215,583,980 ) 215,583,980 — The tables below present the effect of the financial statement adjustments related to the restatement discussed above of the Company’s previously reported balance sheet and statement of shareholders’ equity as of March 31, 2021: As of March 31, 2021 As Previously Adjustment As Restated Total assets $ 250,663,379 $ 250,663,379 Total liabilities $ 20,840,433 $ 20,840,433 Class A ordinary shares subject to possible redemption 224,822,940 25,177,060 250,000,000 Preference shares — — — Class A ordinary shares 252 (252 ) — Class B ordinary shares 625 — 625 Additional paid-in — — — Accumulated deficit 4,999,129 (25,176,808 ) (20,177,679 ) Total shareholders’ equity (deficit) $ 5,000,006 $ (25,177,060 ) $ (20,177,054 ) Total Liabilities, Class A Ordinary Shares Subject to Possible Redemption and Shareholders’ Equity (Deficit) $ 250,663,379 $ — $ 250,663,379 For the three months ended March 31, 2021 As Previously Adjustment As Restated Shares subject to redemption $ (9,238,960 ) $ 9,238,960 $ — The tables below present the effect of the financi a e As of June 30, 2021 As Previously Adjustment As Restated Total assets $ 250,304,732 $ 250,304,732 Total liabilities $ 27,266,392 $ 27,266,392 Class A ordinary shares subject to possible redemption 218,038,330 31,961,670 250,000,000 Preference shares — — — Class A ordinary shares 320 (320 ) — Class B ordinary shares 625 — 625 Additional paid-in 6,784,542 (6,784,542 ) — Accumulated deficit (1,785,477 ) (25,176,808 ) (26,962,285 ) Total shareholders’ equity (deficit) $ 5,000,010 $ (31,961,670 ) $ (26,961,660 ) Total Liabilities, Class A Ordinary Shares Subject to Possible Redemption and Shareholders’ Equity (Deficit) $ 250,304,732 $ — $ 250,304,732 For the six months ended June 30, 2021 As Previously Adjustment As Restated Shares subject to redemption $ 6,784,610 $ (6,784,610 ) $ — In connection with the change in presentation for the Class A ordinary shares subject to possible redemption, the Company has restated its earnings per share calculation to allocate income and losses shared pro rata between the two classes of shares. This presentation contemplates a Business Combination as the most likely outcome, in which case, both classes of shares participate pro rata in the income and losses of the Company. The impact to the reported amounts of weighted average shares outstanding and basic and diluted earnings per common share is presented below for the Affected Quarterly and Annual Periods: EPS for Class A ordinary shares (redeemable) As Previously Adjustment As Restated Form 10-Q Earnings allocable to ordinary shares subject to possible redemption $ 3,321 $ 7,387,849 $ 7,391,170 Weighted average shares outstanding 21,568,664 3,431,336 25,000,000 Basic and diluted earnings per share $ — $ 0.30 $ 0.30 Form 10-Q Earnings (loss) allocable to ordinary shares subject to possible redemption $ 3,293 $ (5,430,978 ) $ (5,427,685 ) Weighted average shares outstanding 22,474,838 2,525,162 25,000,000 Basic and diluted earnings per share $ — $ (0.22 ) $ (0.22 ) Form 10-Q Earnings allocable to ordinary shares subject to possible redemption $ 6,514 $ 1,956,972 $ 1,963,486 Weighted average shares outstanding 22,024,254 2,975,746 25,000,000 Basic and diluted earnings per share $ — $ 0.08 $ 0.08 EPS for Class B ordinary shares (non-redeemable) As Previously Adjustment As Restated Form 10-Q Earnings allocable to non-redeemable ordinary shares $ 9,235,642 $ (7,387,849 ) $ 1,847,793 Weighted average shares outstanding 9,681,336 (3,431,336 ) 6,250,000 Basic and diluted earnings per share $ 0.95 $ (0.65 ) $ 0.30 Form 10-Q Loss allocable to non-redeemable ordinary shares $ (6,787,899 ) $ 5,430,978 $ (1,356,921 ) Weighted average shares outstanding 8,775,162 (2,525,162 ) 6,250,000 Basic and diluted earnings per share $ (0.77 ) $ 0.55 $ (0.22 ) Form 10-Q Earnings allocable to non-redeemable ordinary shares $ 2,447,843 $ (1,956,972 ) $ 490,871 Weighted average shares outstanding 9,225,746 (2,975,746 ) 6,250,000 Basic and diluted earnings per share $ 0.27 $ (0.19 ) $ 0.08 EPS for Class A ordinary shares (redeemable) As Previously Adjustment As Restated Form 10-Q Earnings (loss) allocable to ordinary shares subject to possible redemption $ 3,841 $ (2,378,506 ) $ (2,374,665 ) Weighted average shares outstanding 21,810,415 (18,022,536 ) 3,787,879 Basic and diluted earnings per share $ — $ (0.08 ) $ (0.08 ) Form 10-K/A Earnings (loss) allocable to ordinary shares subject to possible redemption $ — $ (293,337 ) $ (293,337 ) Weighted average shares outstanding 21,719,426 (5,580,185 ) 16,139,241 Basic and diluted earnings per share $ — $ (0.15 ) $ (0.15 ) EPS for Class B ordinary shares (non- As Previously Adjustment As Restated Form 10-Q (September 30, 2020) - the period from July 21, 2020 (inception) through September 30, 2020 Loss allocable to non-redeemable ordinary shares $ (777,344 ) $ 293,337 $ (484,007 ) Weighted average shares outstanding 6,732,994 (482,994 ) 6,250,000 Basic and diluted earnings per share $ (0.12 ) $ 0.04 $ (0.08 ) Form 10-K/A (December 31, 2020) - the period from July 21, 2020 (inception) through December 31, 2020 Loss allocable to non-redeemable ordinary shares $ (3,298,105 ) $ 2,378,505 $ (919,600 ) Weighted average shares outstanding 8,310,766 (2,060,766 ) 6,250,000 Basic and diluted earnings per share $ (0.40 ) $ 0.25 $ (0.15 )
ACON S2 Acquisition Corp [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Restatement of Financial Statements	Note 2—Restatement of Financial Statements Amendment No. 1 In April 2021, the Company concluded that, because of a misapplication of the accounting guidance related to its Public and Private Placement warrants the Company issued in September 2020, the Company’s previously issued financial statements for the Affected Periods should no longer be relied upon. As such, the Company is restating its financial statements for the Affected Periods included in this Annual Report. On April 12, 2021, the staff of the Securities and Exchange Commission (the “SEC Staff”) issued a public statement entitled “Staff Statement on Accounting and Reporting Considerations for Warrants issued by Special Purpose Acquisition Companies (“SPACs”) (the “SEC Staff Statement”). In the SEC Staff Statement, the SEC Staff expressed its view that certain terms and conditions common to SPAC warrants may require the warrants to be classified as liabilities on the SPAC’s balance sheet as opposed to equity. Since issuance on September 21, 2020 the Company’s warrants were accounted for as equity within the Company’s previously reported balance sheets, and after discussion and evaluation, including with the Company’s independent auditors, management concluded that the warrants should be presented as liabilities with subsequent fair value remeasurement. Historically, the Warrants were reflected as a component of equity as opposed to liabilities on the balance sheets and the statements of operations did not include the subsequent non-cash changes in estimated fair value of the Warrants, based on our application of FASB ASC Topic 815-40, Derivatives and Hedging, Contracts in Entity’s Own Equity issued on September 21, 2020, in light of the SEC Staff’s published views. Based on this reassessment, management determined that the Warrants should be classified as liabilities measured at fair value upon issuance, with subsequent changes in fair value reported in the Company Statement of Operations each reporting period. Therefore, the Company, in consultation with its Audit Committee, concluded that its previously issued financial statements for the periods beginning with the period from July 3, 2020 through December 31, 2020 and the period from July 3, 2020 through September 30, 2020 (collectively, the “Affected Periods”) should be restated because of a misapplication in the guidance around accounting for certain of our outstanding warrants to purchase ordinary shares (the “Warrants”) and should no longer be relied upon. The Warrants were issued in connection with the Company’s Initial Public Offering of 25,000,000 Units and the sale of Private Placement warrants completed on September 21, 2020. Each Unit consists of one of the Company’s Class A ordinary shares, $0.0001 par value, and one-quarter of one redeemable warrant. Each whole Warrant entitles the holder to purchase one of Class A ordinary share at a price of $11.50 per share. The Warrants will expire worthless five years from the date of completion of our initial business combination. The material terms of the warrants are more fully described in Note 8—Derivative Warrant Liabilities. See restated Note 9—Fair Value Measurements. Impact of the Restatement The impact of the restatement on the balance sheets, statements of operations and statements of cash flows for the Affected Periods is presented below. The restatement had no impact on net cash flows from operating, investing or financing activities. The tables below present the effect of the financial statement adjustments related to the restatement discussed above of the Company’s previously reported financial statements as of and for the period from July 21, 2020 (inception) through December 31, 2020: As of December 31, 2020 As Previously Restatement As Restated Balance Sheet Total assets $ 250,827,490 $ — $ 250,827,490 Liabilities and shareholders’ equity Total current liabilities $ 139,107 $ — $ 139,107 Deferred underwriting commissions 8,750,000 — 8,750,000 Derivative warrant liabilities — 21,354,400 21,354,400 Total liabilities 8,889,107 21,354,400 30,243,507 Class A ordinary share, $0.0001 par value; shares subject to possible redemption 236,938,380 (21,354,400 ) 215,583,980 Shareholders’ equity Preference shares—$0.0001 par value — — — Class A ordinary shares—$0.0001 par value 131 213 344 Class B ordinary shares—$0.0001 par value 625 — 625 Additional paid-in-capital 5,703,622 2,589,677 8,293,299 Accumulated deficit (704,375 ) (2,589,890 ) (3,294,265 ) Total shareholders’ equity 5,000,003 — 5,000,003 Total liabilities and shareholders’ equity $ 250,827,490 $ — $ 250,827,490 Period From July 21, 2020 (Inception) Through As Previously Restatement As Restated Statement of Operations Loss from operations $ (708,829 ) $ — $ (708,829 ) Other (expense) income: Change in fair value of derivative warrant liabilities — (1,854,400 ) (1,854,400 ) Financing costs—derivative warrant liabilities — (735,490 ) (735,490 ) Gain on marketable securities (net), and dividends held in Trust Account 4,454 — 4,454 Total other (expense) income 4,454 (2,589,890 ) (2,585,436 ) Net loss $ (704,375 ) $ (2,589,890 ) $ (3,294,265 ) Basic and Diluted weighted-average Class A ordinary share outstanding 23,734,800 21,719,426 Basic and Diluted net income per Class A ordinary shares $ 0.00 $ — Basic and Diluted weighted-average Class B ordinary share outstanding 7,052,256 8,310,766 Basic and Diluted net loss per Class B ordinary shares $ (0.10 ) $ (0.40 ) Period From July 21, 2020 (Inception) Through As Previously Restatement As Restated Statement of Cash Flows Net loss $ (704,375 ) $ (2,589,890 ) $ (3,294,265 ) Adjustments to reconcile net loss to net cash used in operating activities 11,546 2,589,890 2,601,436 Net cash used in operating activities (976,685 ) — (976,685 ) Net cash used in investing activities (250,000,000 ) — (250,000,000 ) Net cash provided by financing activities 251,446,758 — 251,446,758 Net change in cash $ 470,073 $ — $ 470,073 In addition, the impact to the balance sheet dated September 21, 2020, filed on Form 8-K on September 25, 2020 related to the impact of accounting for the public and private warrants as liabilities at fair value resulted in a $19.5 million increase to the derivative warrant liabilities line item at September 21, 2020 and offsetting decrease to the Class A ordinary shares subject to possible redemption mezzanine equity line item. There is no change to total shareholders’ equity at the reported balance sheet date. Quarterly Financial Information (Unaudited) The following tables contain unaudited quarterly financial information for the quarterly period ended September 30, 2020 that has been updated to reflect the restatement of the Company’s financial statements. The restatement had no impact net loss, net cash flows from operating, investing or financing activities. The Company has not amended its previously filed Quarterly Report on Form 10-Q As of September 30, 2020 As Previously Restatement As Restated Unaudited Condensed Balance Sheet Total assets $ 252,167,049 $ — $ 252,167,049 Liabilities and shareholders’ equity Total current liabilities $ 816,145 $ — $ 816,145 Deferred underwriting commissions 8,750,000 — 8,750,000 Derivative warrant liabilities — 19,500,000 19,500,000 Total liabilities 9,566,145 19,500,000 29,066,145 Class A ordinary share, $0.0001 par value; shares subject to possible redemption 237,600,900 (19,500,000 ) 218,100,900 Shareholders’ equity Preference shares—$0.0001 par value — — — Class A ordinary shares—$0.0001 par value 124 195 319 Class B ordinary shares—$0.0001 par value 719 — 719 Additional paid-in-capital 5,041,015 735,295 5,776,310 Accumulated deficit (41,854 ) (735,490 ) (777,344 ) Total shareholders’ equity 5,000,004 — 5,000,004 Total liabilities and shareholders’ equity $ 252,167,049 $ — $ 252,167,049 Period From July 21, 2020 (Inception) Through As Restatement As Restated Unaudited Condensed Statement of Operations Loss from operations $ (41,854 ) $ — $ (41,854 ) Other (expense) income: Change in fair value of derivative warrant liabilities — — — Financing costs—derivative warrant liabilities — (735,490 ) (735,490 ) Total other (expense) income — (735,490 ) (735,490 ) Net loss $ (41,854 ) $ (735,490 ) $ (777,344 ) Basic and Diluted weighted-average Class A ordinary share outstanding — 21,810,415 Basic and Diluted net income per Class A ordinary shares $ — $ — Basic and Diluted weighted-average Class B ordinary share outstanding 6,437,865 6,732,994 Basic and Diluted net loss per Class B ordinary shares $ (0.01 ) $ (0.12 ) Period From July 21, 2020 (Inception) Through As Previously Restatement As Restated Unaudited Condensed Statement of Cash Flows Net loss $ (41,854 ) $ (735,490 ) $ (777,344 ) Adjustment to reconcile net loss to net cash used in operating activities 16,000 735,490 751,490 Net cash used in operating activities (26,800 ) — (26,800 ) Net cash used in investing activities (250,000,000 ) — (250,000,000 ) Net cash provided by financing activities 251,773,258 — 251,773,258 Net change in cash $ 1,746,458 $ — $ 1,746,458 Amendment No. 2 The Company concluded it should restate its previously issued financial statements by amending Amendment No. 1 to its Annual Report on Form 10-K/A, filed with the SEC on May 24, 2021, to classify all outstanding Class A ordinary shares subject to possible redemption in temporary equity. In accordance with ASC 480-10-S99, earnings per share calculation to allocate income and losses shared pro rata between the two classes of shares. This presentation contemplates a Business Combination as the most likely outcome, in which case, both classes of shares share pro rata in the income and losses of the Company. As a result, the Company restated its previously filed financial statements to present all redeemable Class A ordinary shares as temporary equity and to recognize a remeasurement adjustment from the initial book value to redemption value at the time of its Initial Public Offering. The Company’s previously filed financial statements that contained the error were initially reported in the Company’s Form 8-K filed with the SEC on September 25, 2020 (the “Post-IPO Balance Sheet”), the Company’s Form 10-Q for the quarterly period ended September 30, 2020, and the Company’s Annual Report on 10-K for the annual period ended December 31, 2020, which were previously restated in the Company’s Amendment No. 1 to its Form 10-K as filed with the SEC on May 24, 2021, (collectively the “Affected Periods”). These financial statements restate the Company’s previously issued audited and unaudited financial statements covering the periods through December 31, 2020. Impact of the Restatement The change in the carrying value of the redeemable Class A ordinary shares in the IPO Balance Sheet resulted in a reclassification of approximately 3.2 million Class A ordinary shares from permanent equity to temporary equity as presented below. The impact is presented below: As of September 21, 2020 As Reported, As Restated Adjustment As Restated Balance Sheet Total assets $ 252,174,258 $ — $ 252,174,258 Total liabilities $ 29,049,500 $ — $ 29,049,500 Class A ordinary shares subject to possible redemption 218,124,750 31,875,250 250,000,000 Preference shares — — — Class A ordinary shares 319 (319 ) — Class B ordinary shares 719 — 719 Additional paid-in 5,747,460 (5,747,460 ) — Accumulated deficit (748,490 ) (26,127,471 ) (26,875,961 ) Total shareholders’ equity (deficit) $ 5,000,008 $ (31,875,250 ) $ (26,875,242 ) Total Liabilities, Class A Ordinary Shares Subject to Possible Redemption and Shareholders’ Equity (Deficit) $ 252,174,258 $ — $ 252,174,258 The table below presents the effect of the financial statement adjustments related to the restatement discussed above of the Company’s previously reported financial statements as of December 31, 2020 and for the period from July 21, 2020 (inception) through December 31, 2020: As of December 31, 2020 As Previously Restatement As Restated Balance Sheet Total assets $ 250,827,490 $ — $ 250,827,490 Total liabilities 30,243,507 — 30,243,507 Class A ordinary shares subject to possible redemption 215,583,980 34,416,020 250,000,000 Shareholders’ equity Preference shares - $0.0001 par value — — — Class A ordinary shares - $0.0001 par value 344 (344 ) — Class B ordinary shares - $0.0001 par value 625 — 625 Additional paid-in-capital 8,293,299 (8,293,299 ) — Accumulated deficit (3,294,265 ) (26,122,377 ) (29,416,642 ) Total shareholders’ equity 5,000,003 (34,416,020 ) (29,416,017 ) Total liabilities and shareholders’ equity $ 250,827,490 $ — $ 250,827,490 Period From July 21, 2020 (Inception) Through As Previously Restatement As Restated Statement of Operations Earnings (loss) allocable to ordinary shares subject to possible redemption $ 3,841 (2,378,506 ) $ (2,374,665 ) Basic and Diluted weighted-average Class A ordinary share outstanding 21,719,416 (5,580,185 ) 16,139,241 Basic and Diluted net income per Class A ordinary shares $ 0.00 (0.15 ) $ (0.15 ) Loss allocable to non-redeemable ordinary shares $ (3,298,105 ) 2,378,505 $ (919,600 ) Basic and Diluted weighted-average Class B ordinary share outstanding 8,310,766 (2,060,766 ) 6,250,000 Basic and Diluted net loss per Class B ordinary shares $ (0.40 ) 0.25 $ (0.15 ) Period From July 21, 2020 (Inception) Through As Previously Restatement As Restated Statement of Shareholders’ Deficit Sale of units in initial public offering, gross $ 237,500,000 $ (237,500,000 ) $ — Offering costs (13,646,752 ) 13,646,752 — Remeasurement of Class A ordinary shares subject to possible redemption — (26,146,471 ) (26,146,471 ) Shares subject to possible redemption (215,583,980 ) 215,583,980 — Quarterly Financial Information (Unaudited) The following tables contain unaudited quarterly financial information for the quarterly period ended September 30, 2020 that has been updated to reflect the restatement of the Company’s financial statements. The restatement had no impact net loss, net cash flows from operating, investing or financing activities. The Company has not amended its previously filed Quarterly Report on Form 10-Q As of September 30, 2020 As Previously Restatement As Restated Unaudited Condensed Balance Sheet Total assets $ 252,167,049 $ — $ 252,167,049 Total liabilities 29,066,145 — 29,066,145 Class A ordinary share, $0.0001 par value; shares subject to possible redemption 218,100,900 31,899,100 250,000,000 Shareholders’ equity Preference shares - $0.0001 par value — — — Class A ordinary shares - $0.0001 par value 319 (319 ) — Class B ordinary shares - $0.0001 par value 719 — 719 Additional paid-in-capital 5,776,310 (5,776,310 ) — Accumulated deficit (777,344 ) (26,122,471 ) (26,899,815 ) Total shareholders’ equity 5,000,004 (31,899,100 ) (26,899,096 ) Total liabilities and shareholders’ equity $ 252,167,049 $ — $ 252,167,049 Period From July 21, 2020 (Inception) Through As Previously Restatement As Restated Unaudited Statement of Operations Earnings (loss) allocable to ordinary shares subject to possible redemption $ — (293,337 ) $ (293,337 ) Basic and Diluted weighted-average Class A ordinary share outstanding 21,810,415 (18,022,536 ) 3,787,879 Basic and Diluted net income (loss) per Class A ordinary shares $ — (0.08 ) $ (0.08 ) Loss allocable to non-redeemable ordinary shares $ (777,344 ) 293,337 $ (484,007 ) Basic and Diluted weighted-average Class B ordinary share outstanding 6,732,994 (482,994 ) 6,250,000 Basic and Diluted net loss per Class B ordinary shares $ (0.12 ) 0.04 $ (0.08 ) Period From July 21, 2020 (Inception) Through As Previously Restatement As Restated Statement of Shareholders’ Deficit Sale of units in initial public offering, gross $ 237,500,000 $ (237,500,000 ) $ — Offering costs (13,646,752 ) 13,646,752 — Remeasurement of Class A ordinary shares subject to possible redemption — (26,146,471 ) (26,146,471 ) Shares subject to possible redemption 218,124,750 (218,124,750 ) —

Restatement of Previously Issue

Restatement of Previously Issued Financial Statements	9 Months Ended
	Sep. 30, 2021
Accounting Standards Update and Change in Accounting Principle [Abstract]
Restatement of Previously Issued Financial Statements	Note 2 - Restatement of Previously Issued Financial Statements In preparation of the Company’s unaudited condensed consolidated financial statements as of and for the quarterly period ended September 30, 2021, the Company concluded it should restate its previously issued financial statements to classify all Class A ordinary shares subject to possible redemption in temporary equity. In accordance with the Financial Accounting Standard Board’s (“FASB”) Accounting Standards Codification (“ASC”) Topic 480 “Distinguishing Liabilities from Equity” (“ASC 480”), paragraph 480-10-S99, In accordance with SEC Staff Accounting Bulletin No. 99, “Materiality,” and SEC Staff Accounting Bulletin No. 108, “Considering the Effects of Prior Year Misstatements when Quantifying Misstatements in Current Year Financial Statements,” the Company evaluated the corrections and has determined that the related impact was material to the previously filed financial statements that contained the error, reported in the Company’s Form 8-K filed with the SEC on September 25, 2020 (the “Post-IPO Balance Sheet”) and the Company’s Form 10-Qs for the quarterly periods ended September 30, 2020, March 31, 2021, and June 30, 2021 and the Company’s 10-K/A filed with the SEC on May 24, 2021 (the “Affected Quarterly Periods”). Therefore, the Company, in consultation with its Audit Committee, concluded that the Post-IPO Balance Sheet and the Affected Quarterly Periods should be restated to present all Class A ordinary shares subject to possible redemption as temporary equity and to recognize a remeasurement adjustment from the initial book value to redemption value at the time of its Initial Public Offering. As such, the Company is reporting these restatements to those periods in this quarterly report. The previously presented Post-IPO Balance Sheet and Affected Quarterly Periods should no longer be relied upon. Impact of the Restatement The change in the carrying value of the Class A ordinary shares subject to possible redemption in the Post-IPO Balance Sheet resulted in a decrease of approximately $5.7 million in additional paid-in-capital and an increase of approximately $26.1 million to accumulated deficit, as well as a reclassification of $31.9 million Class A ordinary shares from permanent equity to temporary equity. As of September 21, 2020 As Reported Adjustment As Restated Total assets $ 252,174,258 $ 252,174,258 Total liabilities $ 29,049,500 $ 29,049,500 Class A ordinary shares subject to possible redemption 218,124,750 31,875,250 250,000,000 Preference shares — — — Class A ordinary shares 319 (319 ) — Class B ordinary shares 719 — 719 Additional paid-in 5,747,460 (5,747,460 ) — Accumulated deficit (748,490 ) (26,127,471 ) (26,875,961 ) Total shareholders’ equity (deficit) $ 5,000,008 $ (31,875,250 ) $ (26,875,242 ) Total Liabilities, Class A Ordinary Shares Subject to Possible Redemption and Shareholders’ Equity (Deficit) $ 252,174,258 $ — $ 252,174,258 The impact of the restatement on the balance sheets and statements of shareholders’ equity for the Affected Quarterly and Annual Periods is presented below. The restatement had no impact on net income or net cash flows from operating, investing or financing activities. The tables below present the effect of the financial statement adjustments related to the restatement discussed above of the Company’s previously reported balance sheet and statements of shareholders’ equity as of September 30, 2020: As of September 30, 2020 As Reported Adjustment As Restated Total assets $ 252,167,049 $ 252,167,049 Total liabilities $ 29,066,145 $ 29,066,145 Class A ordinary shares subject to possible redemption 218,100,900 31,899,100 250,000,000 Preference shares — — — Class A ordinary shares 319 (319 ) — Class B ordinary shares 719 — 719 Additional paid-in 5,776,310 (5,776,310 ) — Accumulated deficit (777,344 ) (26,122,471 ) (26,899,815 ) Total shareholders’ equity (deficit) $ 5,000,004 $ (31,899,100 ) $ (26,899,096 ) Total Liabilities, Class A Ordinary Shares Subject to Possible Redemption and Shareholders’ Equity (Deficit) $ 252,167,049 $ — $ 252,167,049 Statement of changes in Stockholders’ equity As Previously Adjustment As Restated Sale of units in initial public offering, gross $ 237,500,000 $ (237,500,000 ) $ — Offering costs $ (13,646,752 ) 13,646,752 — Remeasurement of Class A ordinary shares subject to possible redemption — (26,146,752 ) (26,146,752 ) Shares subject to possible redemption 218,100,900 (218,100,900 ) — The tables below present the effect of the financial statement adjustments related to the restatement discussed above of the Company’s previously reported balance sheet and statement of shareholders’ equity as of December 31, 2020: As of December 31, 2020 As Reported Adjustment As Restated Total assets $ 250,827,490 $ 250,827,490 Total liabilities $ 30,243,507 $ 30,243,507 Class A ordinary shares subject to possible redemption 215,583,980 34,416,020 250,000,000 Preference shares — — — Class A ordinary shares 344 (344 ) — Class B ordinary shares 625 — 625 Additional paid-in 8,293,299 (8,293,299 ) — Accumulated deficit (3,294,265 ) (26,122,377 ) (29,416,642 ) Total shareholders’ equity (deficit) $ 5,000,003 $ (34,416,020 ) $ (29,416,017 ) Total Liabilities, Class A Ordinary Shares Subject to Possible Redemption and Shareholders’ Equity (Deficit) $ 250,827,490 $ — $ 250,827,490 Statement of changes in Stockholders’ equity As Previously Adjustment As Restated Sale of units in initial public offering, gross $ 237,500,000 $ (237,500,000 ) $ — Offering costs $ (13,646,752 ) 13,646,752 — Remeasurement of Class A ordinary shares subject to possible redemption — (26,146,752 ) (26,146,752 ) Shares subject to possible redemption (215,583,980 ) 215,583,980 — The tables below present the effect of the financial statement adjustments related to the restatement discussed above of the Company’s previously reported balance sheet and statement of shareholders’ equity as of March 31, 2021: As of March 31, 2021 As Previously Adjustment As Restated Total assets $ 250,663,379 $ 250,663,379 Total liabilities $ 20,840,433 $ 20,840,433 Class A ordinary shares subject to possible redemption 224,822,940 25,177,060 250,000,000 Preference shares — — — Class A ordinary shares 252 (252 ) — Class B ordinary shares 625 — 625 Additional paid-in — — — Accumulated deficit 4,999,129 (25,176,808 ) (20,177,679 ) Total shareholders’ equity (deficit) $ 5,000,006 $ (25,177,060 ) $ (20,177,054 ) Total Liabilities, Class A Ordinary Shares Subject to Possible Redemption and Shareholders’ Equity (Deficit) $ 250,663,379 $ — $ 250,663,379 For the three months ended March 31, 2021 As Previously Adjustment As Restated Shares subject to redemption $ (9,238,960 ) $ 9,238,960 $ — The tables below present the effect of the financi a e As of June 30, 2021 As Previously Adjustment As Restated Total assets $ 250,304,732 $ 250,304,732 Total liabilities $ 27,266,392 $ 27,266,392 Class A ordinary shares subject to possible redemption 218,038,330 31,961,670 250,000,000 Preference shares — — — Class A ordinary shares 320 (320 ) — Class B ordinary shares 625 — 625 Additional paid-in 6,784,542 (6,784,542 ) — Accumulated deficit (1,785,477 ) (25,176,808 ) (26,962,285 ) Total shareholders’ equity (deficit) $ 5,000,010 $ (31,961,670 ) $ (26,961,660 ) Total Liabilities, Class A Ordinary Shares Subject to Possible Redemption and Shareholders’ Equity (Deficit) $ 250,304,732 $ — $ 250,304,732 For the six months ended June 30, 2021 As Previously Adjustment As Restated Shares subject to redemption $ 6,784,610 $ (6,784,610 ) $ — In connection with the change in presentation for the Class A ordinary shares subject to possible redemption, the Company has restated its earnings per share calculation to allocate income and losses shared pro rata between the two classes of shares. This presentation contemplates a Business Combination as the most likely outcome, in which case, both classes of shares participate pro rata in the income and losses of the Company. The impact to the reported amounts of weighted average shares outstanding and basic and diluted earnings per common share is presented below for the Affected Quarterly and Annual Periods: EPS for Class A ordinary shares (redeemable) As Previously Adjustment As Restated Form 10-Q Earnings allocable to ordinary shares subject to possible redemption $ 3,321 $ 7,387,849 $ 7,391,170 Weighted average shares outstanding 21,568,664 3,431,336 25,000,000 Basic and diluted earnings per share $ — $ 0.30 $ 0.30 Form 10-Q Earnings (loss) allocable to ordinary shares subject to possible redemption $ 3,293 $ (5,430,978 ) $ (5,427,685 ) Weighted average shares outstanding 22,474,838 2,525,162 25,000,000 Basic and diluted earnings per share $ — $ (0.22 ) $ (0.22 ) Form 10-Q Earnings allocable to ordinary shares subject to possible redemption $ 6,514 $ 1,956,972 $ 1,963,486 Weighted average shares outstanding 22,024,254 2,975,746 25,000,000 Basic and diluted earnings per share $ — $ 0.08 $ 0.08 EPS for Class B ordinary shares (non-redeemable) As Previously Adjustment As Restated Form 10-Q Earnings allocable to non-redeemable ordinary shares $ 9,235,642 $ (7,387,849 ) $ 1,847,793 Weighted average shares outstanding 9,681,336 (3,431,336 ) 6,250,000 Basic and diluted earnings per share $ 0.95 $ (0.65 ) $ 0.30 Form 10-Q Loss allocable to non-redeemable ordinary shares $ (6,787,899 ) $ 5,430,978 $ (1,356,921 ) Weighted average shares outstanding 8,775,162 (2,525,162 ) 6,250,000 Basic and diluted earnings per share $ (0.77 ) $ 0.55 $ (0.22 ) Form 10-Q Earnings allocable to non-redeemable ordinary shares $ 2,447,843 $ (1,956,972 ) $ 490,871 Weighted average shares outstanding 9,225,746 (2,975,746 ) 6,250,000 Basic and diluted earnings per share $ 0.27 $ (0.19 ) $ 0.08 EPS for Class A ordinary shares (redeemable) As Previously Adjustment As Restated Form 10-Q Earnings (loss) allocable to ordinary shares subject to possible redemption $ 3,841 $ (2,378,506 ) $ (2,374,665 ) Weighted average shares outstanding 21,810,415 (18,022,536 ) 3,787,879 Basic and diluted earnings per share $ — $ (0.08 ) $ (0.08 ) Form 10-K/A Earnings (loss) allocable to ordinary shares subject to possible redemption $ — $ (293,337 ) $ (293,337 ) Weighted average shares outstanding 21,719,426 (5,580,185 ) 16,139,241 Basic and diluted earnings per share $ — $ (0.15 ) $ (0.15 ) EPS for Class B ordinary shares (non- As Previously Adjustment As Restated Form 10-Q (September 30, 2020) - the period from July 21, 2020 (inception) through September 30, 2020 Loss allocable to non-redeemable ordinary shares $ (777,344 ) $ 293,337 $ (484,007 ) Weighted average shares outstanding 6,732,994 (482,994 ) 6,250,000 Basic and diluted earnings per share $ (0.12 ) $ 0.04 $ (0.08 ) Form 10-K/A (December 31, 2020) - the period from July 21, 2020 (inception) through December 31, 2020 Loss allocable to non-redeemable ordinary shares $ (3,298,105 ) $ 2,378,505 $ (919,600 ) Weighted average shares outstanding 8,310,766 (2,060,766 ) 6,250,000 Basic and diluted earnings per share $ (0.40 ) $ 0.25 $ (0.15 )

Summary of Significant Accounti

Summary of Significant Accounting Policies	5 Months Ended	9 Months Ended
	Dec. 31, 2020	Sep. 30, 2021
Significant Accounting Policies		Significant Accounting Policies There have been no material changes in the significant accounting policies described in our Audited Financial Statements as of and for the year ended December 31, 2020.
ACON S2 Acquisition Corp [Member]
Significant Accounting Policies	Note 3—Summary of Significant Accounting Policies Use of Estimates The preparation of financial statements in conformity with GAAP requires t he Cash and Cash Equivalents The Company considers all short-term investments with an original maturity of three months or less when purchased to be cash equivalents. As of December 31, 2020, the Company did not have any cash equivalents. Investments Held in Trust Account Upon the closing of the Initial Public Offering and the Private Placement, $250.0 million of the net proceeds of the sale of the Units in the Initial Public Offering and the Private Placement were placed in the Trust Account and invested in money market funds meeting certain conditions under Rule 2a-7 promulgated using Concentration of Credit Risk Financial instruments that potentially subject the Company to concentrations of credit risk consist of cash accounts in a financial institution, which, at times, may exceed the Federal Depository Insurance Coverage of $250,000, and investments held in Trust Account. At December 31, 2020, the Company has not experienced losses on these accounts. Fair Value of Financial Instruments Fair value is defined as the price that would be received for sale of an asset or paid for transfer of a liability, in an orderly transaction between market participants at the measurement date. GAAP establishes a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). These tiers include: • Level 1, defined as observable inputs such as quoted prices for identical instruments in active markets; • Level 2, defined as inputs other than quoted prices in active markets that are either directly or indirectly observable such as quoted prices for similar instruments in active markets or quoted prices for identical or similar instruments in markets that are not active; and • Level 3, defined as unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions, such as valuations derived from valuation techniques in which one or more significant inputs or significant value drivers are unobservable. In some circumstances, the inputs used to measure fair value might be categorized within different levels of the fair value hierarchy. In those instances, the fair value measurement is categorized in its entirety in the fair value hierarchy based on the lowest level input that is significant to the fair value measurement. As of December 31, 2020, the carrying values of cash approximate their fair values due to the short-term nature of the instruments. As of December 31, 2020, the Company’s portfolio of investments held in the Trust Account is comprised entirely of investments in money market funds that invest in U.S. government securities. Derivative Warrant Liabilities The Company does not use derivative instruments to hedge exposures to cash flow, market, or foreign currency risks. The Company evaluates all of its financial instruments, including issued stock purchase warrants, to determine if such instruments are derivatives or contain features that qualify as embedded derivatives, pursuant to ASC 480 and ASC 815-15. re-assessed The Company issued an aggregate of 8,333,333 ordinary shares warrants associated with Units issued to investors in our Initial Public Offering and the underwriters’ exercise of their overallotment option and we issued 4,666,667 Private Placement Warrants. All of our outstanding warrants are recognized as derivative liabilities in accordance with ASC 815-40. Offering Costs Associated with the Initial Public Offering Offering costs consisted of legal, accounting, and other costs incurred that were directly related to the Initial Public Offering. Offering costs are allocated to the separable financial instruments issued in the Initial Public Offering based on a relative fair value basis, compared to total proceeds received. Offering costs associated with warrant liabilities are expensed as incurred, presented as non-operating non-current Class A Ordinary Shares Subject to Possible Redemption The Company accounts for its Class A ordinary shares subject to possible redemption in accordance with the guidance in ASC Topic 480 “Distinguishing Liabilities from Equity.” Class A ordinary shares subject to mandatory redemption (if any) are classified as liability instruments and are measured at fair value. Conditionally redeemable Class A ordinary shares (including Class A ordinary shares that feature redemption rights that are either within the control of the holder or subject to redemption upon the occurrence of uncertain events not solely within the Company’s control) are classified as temporary equity. At all other times, Class A ordinary shares are classified as shareholders’ equity. The Company’s Class A ordinary shares feature certain redemption rights that are considered to be outside of the Company’s control and subject to the occurrence of uncertain future events. Accordingly, at December 31, 2020, 25,000,000 Class A ordinary shares subject to possible redemption are presented as temporary equity, outside of the shareholders’ equity section of the Company’s balance sheet. Immediately upon the closing of the Initial Public Offering, the Company recognized the remeasurement from initial book value to redemption amount. The change in the carrying value of Class A ordinary shares subject to possible redemption resulted in charges against additional paid-in Income Taxes The Company follows the asset and liability method of accounting for income taxes under FASB ASC 740, “Income Taxes.” Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to differences between the financial statements carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that included the enactment date. Valuation allowances are established, when necessary, to reduce deferred tax assets to the amount expected to be realized. Deferred tax assets were deemed immaterial as of December 31, 2020. FASB ASC 740 prescribes a recognition threshold and a measurement attribute for the financial statement recognition and measurement of tax positions taken or expected to be taken in a tax return. For those benefits to be recognized, a tax position must be more likely than not to be sustained upon examination by taxing authorities. There were no unrecognized tax benefits as of December 31, 2020. The Company recognizes accrued interest and penalties related to unrecognized tax benefits as income tax expense. No amounts were accrued for the payment of interest and penalties as of December 31, 2020. The Company is currently not aware of any issues under review that could result in significant payments, accruals or material deviation from its position. The Company is subject to income tax examinations by major taxing authorities since inception. Net Loss Per Ordinary Share The Company has two classes of shares, Class A ordinary shares and Class B ordinary shares. Income For the period from July 21, 2020 (inception) through December 31, 2020 Class A Class B (restated) Basic and diluted net loss per common share: Numerator: Allocation of net loss $ (2,374,665 ) $ (919,600 ) Denominator: Basic and diluted weighted average common shares outstanding 16,139,241 6,250,000 Basic and diluted net loss per common share $ (0.15 ) $ (0.15 ) Recent Accounting Standards Management does not believe that any recently issued, but not yet effective, accounting standards if currently adopted would have a material effect on the Company’s financial statements.	Note 3 - Summary of Significant Accounting Policies Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires the Company’s management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, including, but not limited to, accrued expenses and derivative warrant liabilities. Making estimates requires management to exercise significant judgment. It is at least reasonably possible that the estimate of the effect of a condition, situation or set of circumstances that existed at the date of the financial statements, which management considered in formulating its estimate, could change in the near term due to one or more future confirming events. Accordingly, the actual results could differ significantly from those estimates. Cash and Cash Equivalents The Company considers all short-term investments with an original maturity of three months or less when purchased to be cash equivalents. As of September 30, 2021, the Company did not have any cash equivalents. Investments Held in the Trust Account The Company’s portfolio of investments is comprised of U.S. government securities, within the meaning set forth in Section 2(a)(16) of the Investment Company Act, with a maturity of 185 days or less, or investments in money market funds that invest in U.S. government securities and generally have a readily determinable fair value, or a combination thereof. When the Company’s investments held in the Trust Account are comprised of U.S. government securities, the investments are classified as trading securities. When the Company’s investments held in the Trust Account are comprised of money market funds, the investments are recognized at fair value. Trading securities and investments in money market funds are presented on the condensed balance sheets at fair value at the end of each reporting period. Gains and losses resulting from the change in fair value of these securities is included in unrealized gain on investments held in Trust Account in the accompanying unaudited condensed consolidated statements of operations. The estimated fair values of investments held in the Trust Account are determined using available market information. Concentration of Credit Risk Financial instruments that potentially subject the Company to concentrations of credit risk consist of cash accounts in a financial institution, which, at times, may exceed the Federal Depository Insurance Coverage of $250,000, and investments held in Trust Account. At September 30, 2021 and December 31, 2020, the Company has not experienced losses on these accounts. Fair Value of Financial Instruments The fair value of the Company’s assets and liabilities, which qualify as financial instruments under the FASB ASC Topic 820, “Fair Value Measurements,” approximates the carrying amounts represented in the condensed balance sheets. Fair Value Measurements The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). These tiers include: • Level 1, defined as observable inputs such as quoted prices for identical instruments in active markets; • Level 2, defined as inputs other than quoted prices in active markets that are either directly or indirectly observable such as quoted prices for similar instruments in active markets or quoted prices for identical or similar instruments in markets that are not active; and • Level 3, defined as unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions, such as valuations derived from valuation techniques in which one or more significant inputs or significant value drivers are unobservable. In some circumstances, the inputs used to measure fair value might be categorized within different levels of the fair value hierarchy. In those instances, the fair value measurement is categorized in its entirety in the fair value hierarchy based on the lowest level input that is significant to the fair value measurement. As of September 30, 2021 and December 31, 2020, the carrying values of cash, prepaid expenses, accounts payable and accrued expenses approximate their fair values due to the short-term nature of the instruments. The Company’s investments held in Trust Account are comprised of investments in U.S. Treasury securities with an original maturity of 185 days or less or investments in a money market funds that comprise only U.S. treasury securities and are recognized at fair value. The fair value of investments held in Trust Account is determined using quoted prices in active markets. Working Capital Loan – Related Party The Company has elected the fair value option to account for its working capital loan – related party with its Sponsor as defined and more fully described in Note 5. As a result of applying the fair value option, the Company records each draw at fair value with a gain or loss recognized at issuance, and subsequent changes in fair value are recorded as change in the fair value of working capital loan – related party on the condensed statement of operations. The fair value is based on prices or valuation techniques that require inputs that are both unobservable and significant to the overall fair value measurement. These inputs reflect management’s and, if applicable, an independent third-party valuation firm’s own assumption about the assumptions a market participant would use in pricing the asset or liability. Derivative warrant liabilities The Company does not use derivative instruments to hedge exposures to cash flow, market, or foreign currency risks. The Company evaluates all of its financial instruments, including issued share purchase warrants, to determine if such instruments are derivatives or contain features that qualify as embedded derivatives, pursuant to ASC 480 and FASB ASC Topic 815, “Derivatives and Hedging” (“ASC 815”). The classification of derivative instruments, including whether such instruments should be recorded as liabilities or as equity, is re-assessed The warrants issued in the Initial Public Offering (the “Public Warrants”) and the Private Placement Warrants are recognized as derivative liabilities in accordance with ASC 815-40. re-measurement Offering Costs Associated with the Initial Public Offering Offering costs consisted of legal, accounting, underwriting fees and other costs incurred through the Initial Public Offering that were directly related to the Initial Public Offering. Offering costs were allocated to the separable financial instruments issued in the Initial Public Offering based on a relative fair value basis, compared to total proceeds received. Offering costs associated with derivative warrant liabilities were expensed as incurred and presented as non-operating expenses in the condensed consolidated statements of operations. Offering costs associated with issuance of the Class A ordinary shares were charged against the carrying value of the Class A ordinary shares subject to possible redemption upon the completion of the Initial Public Offering. The Company classifies deferred underwriting commissions as non-current liabilities as their liquidation is not reasonably expected to require the use of current assets or require the creation of current liabilities. Class A Ordinary Shares Subject to Possible Redemption The Company accounts for its Class A ordinary shares subject to possible redemption in accordance with ASC 480. Class A ordinary shares subject to mandatory redemption (if any) is classified as liability instruments and are measured at fair value. Conditionally redeemable Class A ordinary shares (including Class A ordinary shares that feature redemption rights that are either within the control of the holder or subject to redemption upon the occurrence of uncertain events not solely within the Company’s control) are classified as temporary equity. At all other times, Class A ordinary shares are classified as shareholders’ equity. The Company’s Class A ordinary shares feature certain redemption rights that are considered to be outside of the Company’s control and subject to the occurrence of uncertain future events. Accordingly, as of September 30, 2021 and December 31, 2020, 25,000,000 Class A ordinary shares subject to possible redemption are presented at redemption value as temporary equity, outside of the shareholders’ equity section of the Company’s condensed balance sheet. There were no Class A ordinary shares issued or outstanding as of December 31, 2020. Effective with the closing of the Initial Public Offering, the Company recognized the accretion from initial book value to redemption amount, which resulted in charges against additional paid-in Income Taxes The Company follows the asset and liability method of accounting for income taxes under FASB ASC Topic 740, “Income Taxes” (“ASC 740”). Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to differences between the financial statements carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that included the enactment date. Valuation allowances are established, when necessary, to reduce deferred tax assets to the amount expected to be realized. Deferred tax assets were deemed immaterial as of September 30, 2021. ASC 740 prescribes a recognition threshold and a measurement attribute for the financial statement recognition and measurement of tax positions taken or expected to be taken in a tax return. For those benefits to be recognized, a tax position must be more likely than not to be sustained upon examination by taxing authorities. There were no unrecognized tax benefits as of September 30, 2021. The Company recognizes accrued interest and penalties related to unrecognized tax benefits as income tax expense. No amounts were accrued for the payment of interest and penalties as of September 30, 2021. The Company is currently not aware of any issues under review that could result in significant payments, accruals or material deviation from its position. The Company is subject to income tax examinations by major taxing authorities since inception. Net Loss Per Ordinary Share The Company has two classes of shares, Class A ordinary shares and Class B ordinary shares. Income and losses are shared pro rata between the two classes of shares. Net loss per ordinary share is computed by dividing net loss by the weighted-average number of ordinary shares outstanding during the periods. The Company has not considered the effect of the warrants sold in the Initial Public Offering and the Private Placement to purchase an aggregate of 13,000,000, of the Company’s Class A ordinary shares in the calculation of diluted net loss per share, because their exercise is contingent upon further events and their inclusion would be anti-dilutive under the treasury stock method. As a result, diluted net loss per share is the same as basic net loss per share for the three and nine months ended September 30, 2021. The remeasurement adjustment on the Class A ordinary shares subject to possible redemption is excluded from earnings per share as the redemption value approximates fair value. For the Three Months Ended For the Nine Months Ended Class A Class B Class A Class B Basic and diluted net loss per common share: Numerator: Allocation of net loss $ (3,143,854 ) $ (785,964 ) $ (1,180,369 ) $ (295,092 ) Denominator: Basic and diluted weighted average common shares outstanding 25,000,000 6,250,000 25,000,000 6,250,000 Basic and diluted net loss per common share $ (0.13 ) $ (0.13 ) $ (0.05 ) $ (0.05 ) In connection with the change in presentation for the Class A ordinary shares subject to possible redemption, the Company has revised its earnings per share calculation to allocate income and losses shared pro rata between the two classes of shares. This presentation contemplates a Business Combination as the most likely outcome, in which case, both classes of shares participate pro rata in the income and losses of the Company. The impact to the reported amounts of weighted average shares outstanding and basic and diluted earnings per common share is presented below for the period from July 21, 2020 (inception) through September 30, 2020: For the period from Class A Class B (restated) Basic and diluted net loss per common share: Numerator: Allocation of net loss $ (293,337 ) $ (484,007 ) Denominator: Basic and diluted weighted average common shares outstanding 3,787,879 6,250,000 Basic and diluted net loss per common share $ (0.08 ) $ (0.08 ) Recent Adopted Accounting Standards In August 2020, the FASB issued Accounting Standards Update No. 2020-06, Debt-Debt with Conversion and Other Options (Subtopic 470-20) ’ s Own Equity (Subtopic 815-40): ’ s Own Equity 2020-06”), 2020-06 Recent Accounting Standards The Company’s management does not believe that any recently issued, but not yet effective, accounting standards if currently adopted would have a material effect

Initial Public Offering

Initial Public Offering	5 Months Ended	9 Months Ended
	Dec. 31, 2020	Sep. 30, 2021
ACON S2 Acquisition Corp [Member]
Initial Public Offering [Line Items]
Initial Public Offering	Note 4—Initial Public Offering On September 21, 2020, the Company consummated its Initial Public Offering of 25,000,000 Units, at $10.00 per Unit, generating gross proceeds of $250.0 million, and incurring offering costs of approximately $14.4 million, inclusive of approximately $8.8 million in deferred underwriting commissions.	Note 4 - Initial Public Offering On September 21, 2020, the Company consummated its Initial Public Offering of 25,000,000 Units, at $10.00 per Unit, generating gross proceeds of $250.0 million, and incurring offering costs of approximately $14.4 million, inclusive of approximately $8.8 million in deferred underwriting commissions. Each Unit consisted of one Class A ordinary share and one-third

Private Placement

Private Placement	5 Months Ended	9 Months Ended
	Dec. 31, 2020	Sep. 30, 2021
ACON S2 Acquisition Corp [Member]
Private Placement	Note 5—Private Placement Simultaneously with the closing of the Initial Public Offering, the Company consummated the Private Placement of 4,666,667 Private Placement Warrants, at a price of $1.50 per Private Placement Warrant with our Sponsor, generating gross proceeds of $7.0 million. Each whole Private Placement Warrant is exercisable for one whole share of Class A ordinary shares at a price of $11.50 per share. A portion of the proceeds from the sale of the Private Placement Warrants to our Sponsor was added to the proceeds from the Initial Public Offering held in the Trust Account. If the Company does not complete a Business Combination within the Combination Period, the Private Placement Warrants will expire worthless. The Private Placement Warrants will be non-redeemable for Our Sponsor and the Company’s officers and directors agreed, subject to limited exceptions, not to transfer, assign or sell any of their Private Placement Warrants until 30 days	Note 5 - Private Placement Simultaneously with the closing of the Initial Public Offering, the Company consummated the private placement of 4,666,667 Private Placement Warrants, at a price of $1.50 per Private Placement Warrant with our Sponsor, generating gross proceeds of $7.0 million. Each Private Placement Warrant is exercisable for one whole share of Class A ordinary shares at a price of $11.50 per share. A portion of the proceeds from the sale of the Private Placement Warrants to our Sponsor was added to the proceeds from the Initial Public Offering held in the Trust Account. If the Company does not complete a business combination within the Combination Period, the Private Placement Warrants will expire worthless. The Private Placement Warrants will be non-redeemable Our Sponsor and the Company’s officers and directors agreed, subject to limited exceptions, not to transfer, assign or sell any of their Private Placement Warrants until 30 days

Customer Deposits

Customer Deposits	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Customer Deposits	2. CUSTOMER DEPOSITS Customer deposits are classified as other non-current The following table is a rollforward of customer deposits balances for the nine months ended September 30, 2021 and twelve months ended December 31, 2020 (in thousands): September 30, December 31, Customer deposits, beginning balance $ 2,258 $ 2,207 Additions 850 506 Cancellations — (455 ) Customer deposits, ending balance $ 3,108 $ 2,258	2. CUSTOMER DEPOSITS The Company is in the research and development phase. Its product is still being developed and does not yet meet standard specifications. As such and while the Company has entered into sales contracts for pilot units, no revenue was recognized in fiscal years 2020 and 2019 and revenue recognition will be deferred until the Company’s product meets such specifications and control of the goods has been transferred to the customer. The following table is a rollforward of contract balances as of December 31, 2020 and 2019 (in thousands): 2020 2019 Customer deposits - beginning balance $ 2,207 $ 869 Additions 506 1,983 Cancellations (455 ) (645 ) Customer deposits - ending balance $ 2,258 $ 2,207

Loss Per Share

Loss Per Share	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Earnings Per Share [Abstract]
Loss Per Share	3. LOSS PER SHARE The following table presents the calculation of basic and diluted net loss per share attributable to common shareholders (in thousands, except per share data): Three Months Ended 2021 2020 Net loss $ (51,325 ) $ (2,771 ) Weighted-average shares outstanding – Basic and Diluted 8,823,458 7,102,536 Net loss per share - Basic and Diluted $ (5.82 ) $ (0.39 ) Nine Months Ended 2021 2020 Net loss $ (296,685 ) $ (6,200 ) Weighted-average shares outstanding – Basic and Diluted 8,458,054 7,099,532 Net loss per share - Basic and Diluted $ (35.08 ) $ (0.87 ) There were no common stock options, warrants or preferred stock that were dilutive for the three and nine months ended September 30, 2021 and 2020. Due to net losses for the three and nine months ended September 30, 2021 and 2020, basic and diluted net loss per common share were the same, as the effect of potentially dilutive securities would have been anti-dilutive. The following outstanding balances of common share equivalent securities have been excluded from the calculation of diluted weighted-average common shares outstanding because the effect is anti-dilutive for the periods presented: Three Months Ended 2021 2020 Stock options 2,792,655 3,562,417 Redeemable convertible preferred stock 38,768,389 32,865,949 Warrants — 1,738,382 41,561,044 38,166,748 Nine Months Ended 2021 2020 Stock options 2,792,655 3,562,417 Redeemable convertible preferred stock 38,768,389 32,865,949 Warrants — 1,738,382 41,561,044 38,166,748	3. LOSS PER SHARE The following table presents the calculation of basic and diluted net loss per share attributable to common shareholders for the years ended December 31, 2020 and 2019 (in thousands, except per share data): 2020 2019 Net loss $ (30,419 ) $ (11,467 ) Series B Redeemable Convertible Preferred Stock accretion — (79 ) Net Loss to Common Stockholders $ (30,419 ) $ (11,546 ) Weighted-average shares outstanding – Basic and Diluted 7,108,389 7,043,575 Net loss per share – Basic and Diluted $ (4.28 ) $ (1.64 ) There was no common stock, warrants and redeemable convertible preferred stock that were dilutive for the years ended December 31, 2020 and 2019. Due to net losses for the years ended December 31, 2020 and 2019, basic and diluted net loss per common share were the same, as the effect of potentially dilutive securities would have been anti-dilutive. The following outstanding balances of common share equivalent securities have been excluded from the calculation of diluted weighted-average common shares outstanding because the effect is anti-dilutive for the periods presented: 2020 2019 Stock options 3,891,768 2,104,223 Preferred stock 32,865,949 32,865,949 Warrants 1,738,382 1,668,382 38,496,099 36,638,554

Prepaid Expenses And Other Curr

Prepaid Expenses And Other Current Assets	12 Months Ended
	Dec. 31, 2020
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid Expenses And Other Current Assets	4. PREPAID EXPENSES AND OTHER CURRENT ASSETS Prepaid expenses and other current assets consist of the following as of December 31, 2020 and 2019 (in thousands): 2020 2019 Vendor advances $ 473 $ 507 IT services and other office expenses 157 50 Insurance 107 41 Other 56 60 Total prepaids and other current assets $ 793 $ 658

Property And Equipment, Net

Property And Equipment, Net	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Property And Equipment, Net	5. PROPERTY AND EQUIPMENT, NET Property and equipment, net consist of the following as of December 31, 2020 and 2019 (in thousands): 2020 2019 Machinery and equipment $ 2,217 $ 1,430 Furniture and fixtures 90 60 Leasehold improvements 677 496 Construction in process — 389 Total property and equipment 2,984 2,375 Less accumulated depreciation (1,148 ) (712 ) Total property and equipment, net $ 1,836 $ 1,663 Depreciation expense was $436 thousand and $260 thousand for the years ended December 31, 2020 and 2019, respectively.

Accrued and Other Current Liabi

Accrued and Other Current Liabilities	12 Months Ended
	Dec. 31, 2020
Payables and Accruals [Abstract]
Accrued and Other Current Liabilities	6. ACCRUED AND OTHER CURRENT LIABILITIES Accrued and other current liabilities consist of the following as of December 31, 2020 and 2019 (in thousands): 2020 2019 Payroll and related benefits $ 777 $ 351 Materials and related purchases 464 474 Deferred rent 462 524 Professional & consulting fees 248 103 Customer refund — 352 Other 243 22 Total accrued and other current liabilities $ 2,194 $ 1,826

Leases

Leases	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Leases	7. LEASES The Company leases office and manufacturing space in Wilsonville, Oregon under an operating lease that expires February 28, 2025. The future minimum lease payments under non-cancelable 2021 $ 840 2022 865 2023 891 2024 917 2025 157 Future Operating Lease Payments $ 3,670 Rent expense related to operating leases aggregated $837 thousand and $1,048 thousand in 2020 and 2019, respectively. The Company has an option to renew the lease for the office and manufacturing space in Wilsonville for an additional term of 60 months. The Company must provide the landlord with a twelve-month notice of its intention to renew the existing lease prior to its expiry on February 28, 2025. As of the date of issuance of these financial statements, the Company has not provided such notice.

Borrowings

Borrowings	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Debt Disclosure [Abstract]
Borrowings	4. BORROWINGS Long-term debt consists of the following as of September 30, 2021 and December 31, 2020 (in thousands): September 30, December 31, Notes payable $ 4,236 $ 4,761 Bridge loan 21,432 — PPP loan — 936 Total notes payable 25,668 5,697 Less notes payable, current 23,415 5,678 Notes payable, non-current $ 2,253 $ 19 Term Loan for Equipment In September 2019, the Company financed a scanner purchase for $79 thousand. The loan term was 24 months, and the interest rate was 6.9%. In March 2020, the Company financed a machine tool purchase for $50 thousand. The loan term was 36 months, and the interest rate was 8.1%. Both loans’ principal and interest are payable on a monthly basis. In July 2021, the Company fully paid off both loans’ balances. The term loans’ balances as of September 30, 2021 and December 31, 2020 were $0 and $67 thousand, respectively. Payroll Protection Program Loan On April 19, 2020, the Company entered into an unsecured promissory note under the Payroll Protection Program (“the PPP Loan”) with a bank under the PPP administered by the United States Small Business Administration (“SBA”). The principal amount of the PPP Loan was $936 thousand. The PPP Loan bore interest of 1.0% per annum and was disbursed to the Company on April 20, 2020. The PPP Loan had a maturity date of April 20, 2022. Under the terms of the PPP, the Company could apply for, and be granted, forgiveness for all or a portion of the PPP Loan. Such forgiveness would be determined based on the use of the loan proceeds for eligible purposes within the first twenty-four weeks of the loan proceed could be used for mortgage interest, rent, utility costs and the maintenance of employee and compensation levels. In July 2021, the Company applied for and received forgiveness on the $936 thousand PPP Loan plus $12 thousand in accrued interest. The gain on extinguishment of debt of $948 thousand is recorded within other income (expense), net in the Company’s Condensed Statements of Operations and Comprehensive Loss for the three and nine months ended September 30, 2021. Notes Payable In 2018, the Company entered into a $1,000 thousand note payable with a bank that is secured by all property of the Company, except for its intellectual property. The original maturity date of the note was July 1, 2021 but was modified and extended to January 1, 2022 under a Deferral Agreement (“Deferral Agreement”) entered into in April 2020. In March 2020, the Company amended the note payable and borrowed an additional $4,000 thousand. The additional $4,000 thousand borrowing changed the present value of cash flows by more than 10% and, as such, was treated as a debt extinguishment. The Company recognized a $62 thousand loss on extinguishment of debt for the year ended December 31, 2020. The Company’s note payable was recorded at fair value as part of the extinguishment. The $4,000 thousand note payable’s original maturity date was January 1, 2023 but was modified and extended to July 1, 2023 under the Deferral Agreement. The Company accounted for the Deferral Agreement, extending the maturity of the notes payable, as a debt modification based on an analysis of cash flows before and after the debt modification. The notes payable bear interest at 0.50% below the bank’s prime rate as of September 30, 2021 and December 31, 2020 (2.75% interest rate on September 30, 2021 and December 31, 2020). The Company makes monthly interest and principal payments on the notes payable based on the schedule defined in the agreement. In conjunction with the notes payable, the Company issued 68,000 shares of Series B redeemable convertible preferred stock warrants and 70,000 shares of Series C redeemable convertible preferred stock warrants in July 2018 and March 2020, respectively. The Series B redeemable convertible preferred stock warrants and Series C redeemable convertible preferred stock warrants have exercise prices of $1.42 per share and $1.84 per share, respectively, and expire 10 years after issuance. The fair values of the Series B redeemable convertible preferred stock warrants and Series C redeemable convertible preferred stock warrants were $55 thousand and $44 thousand, respectively, at the time of issuance. The fair value of the Series B redeemable convertible preferred stock warrants was initially recorded as a reduction of the value of the notes payable and was amortized over the term of the loan as interest expense using the effective interest method. Unamortized Series B redeemable convertible preferred stock warrants were treated as a component of loss on extinguishment of debt. The Series C redeemable convertible preferred stock warrants were issued in conjunction with the additional $4,000 thousand borrowing and were a component of the loss on extinguishment of debt. There was no interest expense recognized related to the amortization of warrants issued in conjunction with the notes payable for the three months ended September 30, 2021 and 2020. Interest expense of $0 and $4 thousand were recognized related to the amortization of warrants issued in conjunction with the notes payable for the nine months ended September 30, 2021 and 2020, respectively. The audit opinion as of and for the year ended December 31, 2020 financial statements contained a going concern explanatory paragraph. Under the notes payable loan agreement, a going concern opinion with respect to the Company’s audited financial statements is a material adverse change resulting in an event of default. In accordance with a subjective acceleration clause, the Lender had an option to elect to accelerate $4,067 thousand of the Company’s existing indebtedness as of December 31, 2020 to be immediately due and payable. As of December 31, 2020, the event of default would have also accelerated the $943 thousand in principal and interest due on the PPP Loan because of the cross-default provisions. The Company had classified the notes payable and PPP loan as current liabilities as of December 31, 2020 due to the considerations discussed above and the assessment that the material adverse change clause under the notes payable and PPP Loan agreements was not within the Company’s control. As discussed in Note 1, the Merger alleviated the risk related to going concern, as well as that related to the subjective acceleration clause. As a result, $2,253 thousand of the Company’s notes payable have been reclassified from current to noncurrent liabilities as of September 30, 2021. Bridge Loan In July 2021, the Company entered into a six-month paid-in-kind The Company elected the fair value option to account for the Bridge Loan, which contained multiple embedded derivatives. The Company recorded the Bridge Loan at fair value of $20,000 thousand at issuance. Interest expense of $1,432 thousand was recognized and accrued related to the paid in-kind	8. BORROWINGS Long term debt consists of the following as of December 2020 2019 Notes payable $ 4,761 $ 828 PPP loan 936 — Total notes payable 5,697 828 Less current portion of notes payable 5,678 365 Long-term notes payable, net of current portion $ 19 $ 463 Term Loan for Equipment In September 2019, the Company financed a scanner purchase for $79 thousand. The loan term was 24 months, and the interest rate is 6.9%. In March 2020, the Company financed a machine tool purchase for $50 thousand. The loan term was 36 months, and the interest rate was 8.1%. Both loans’ principal and interest are payable on a monthly basis. The term loans’ balance as of December 31, 2020 and 2019 were $67 thousand and $70 thousand, respectively. As of December 31, 2020, principal payments on the Company’s term loan for equipment, are scheduled as follows for the fiscal year ending December 31 (in thousands): 2021 $ 48 2022 18 2023 1 Total principal payments on notes payable $ 67 Payroll Protection Program Loan On April 19, 2020, the Company entered into an unsecured promissory note under the Payroll Protection Program (“the PPP Loan”), with a bank under the PPP administered by the United States Small Business Administration (“SBA”) and authorized by the Keeping American Workers Employed and Paid Act, which is part of the CARES Act, enacted on March 27, 2020. The principal amount of the PPP Loan is $936 thousand. The PPP Loan bears interest of 1.0 % per annum and was disbursed to the Company on April 20, 2020. The PPP Loan has a maturity date of April 20, 2022. The PPP Loan may be prepaid, in full or in part, at any time prior to maturity with no prepayment penalties. Under the terms of the PPP, the Company can apply for, and be granted, forgiveness for all or a portion of the PPP Loan. Such forgiveness will be determined based on the use of the loan proceed for eligible purposes within the first twenty-four week The Company can apply for loan forgiveness during the two-year The Company’s event of default on its notes payable (see “Notes Payable” section below) results in a cross-default on the PPP Loan. The PPP Loan may be called by the Lender and be due and payable immediately. Notes Payable In 2018, the Company entered into a $1,000 thousand note payable with a bank that is secured by all property of the Company, except for its intellectual property. The note payable’s original maturity date was July 1, 2021 but was modified and extended to January 1, 2022 under a Deferral Agreement (“Deferral Agreement”) entered into in April 2020. In March 2020, the Company amended the note payable and borrowed an additional $4,000 thousand. The additional $4,000 thousand borrowing changed the present value of cash flows by more than 10% and, as such, was treated as a debt extinguishment. The Company recognized a $62 thousand loss on extinguishment of debt for the year ended December 31, 2020. The Company’s notes payable to the bank were recorded at fair value as part of the extinguishment. The $4,000 thousand note payable’s original maturity date was on January 1, 2023 but was modified and extended to July 1, 2023 under the Deferral Agreement. The Company accounted for the Deferral Agreement, extending the maturity of the notes, as a debt modification based on an analysis of cash flows before and after the debt modification. The notes payable bear interest at 0.50% below the bank’s prime rate (2.75% notes payable rate on December 31, 2020). The Company makes monthly interest and principal payments on the note payable based on the schedule defined in the agreement. In conjunction with the notes payable, the Company issued warrants to purchase 68,000 shares of Series B redeemable convertible preferred stock and 70,000 shares of Series C redeemable convertible preferred stock in July 2018 and March 2020, respectively. The Series B redeemable convertible preferred stock warrants and Series C redeemable convertible preferred stock warrants have exercise prices of $1.42 and $1.84 per share, respectively and expire 10 years after issuance. The fair value of Series B redeemable convertible preferred stock warrants and Series C redeemable convertible preferred stock warrants were $55 thousand and $44 thousand, respectively, at the time of issuance. The fair value of the Series B redeemable convertible preferred stock warrants was initially recorded as a reduction of the value of the notes payable and were amortized over the term of the loan as interest expense using the effective interest rate method. Unamortized Series B redeemable convertible preferred stock warrants were treated as a component of loss on extinguishment of debt. The Series C redeemable convertible preferred stock warrants were issued in conjunction with the additional $4,000 thousand borrowing and were a component of the loss on extinguishment of debt. Interest expense of $4 thousand and $21 thousand were recognized related to the amortization of warrants issued in conjunction with the notes payable for the years ended December 31, 2020 and December 31, 2019, respectively. The audit opinion as of and for the year ended December 31, 2020 financial statements contains a going concern explanatory paragraph. Under the notes payable loan agreement, a going concern opinion with respect to the Company’s audited financial statements is a material adverse change resulting in an event of default. In accordance with a subjective acceleration clause, the Lender may elect to accelerate $4,583 thousand of the Company’s existing indebtedness as of December 31, 2020 to be immediately due and payable. The event of default would also accelerate the $943 thousand in principal and accrued interest due on the PPP loan because of the cross-default provisions. The Company does not currently have sufficient liquidity to repay all its outstanding debt in full if such debt is accelerated. The Company has classified the notes payable and PPP Loan as current in the financial statements as of December 31, 2020 due to the considerations discussed above and the assessment that the material adverse change clause under the notes payable and PPP Loan agreement is not within the Company’s control. The Company has not been notified of an event of default by the Lender as of the date of issuance of these financial statements. Convertible Notes Payable The Company issued convertible notes payable with face values of $6,518 thousand and $2,722 thousand in 2018 and 2019, respectively. Both notes bore interest at 8% and they were automatically converted upon issuance of the Series C-1 C-1 The 2018 convertible notes payable were issued with detachable Series B redeemable convertible preferred stock warrants, which contained automatic conversion features upon a change in control, bridge financing or qualified financing in excess of $10,000 thousand (the “2018 Convertible Note Automatic Conversion Rights”). The 2018 Convertible Note Automatic Conversion Rights qualified as an embedded derivative as the 2018 convertible notes were issued at a substantial discount when considering the value of warrants issued. The 2018 Convertible Note Automatic Conversion Rights were recorded at their initial fair value as liabilities at issuance and were adjusted to fair value at each reporting date, with the change in fair value recorded as a component of other income and expense in the statements of operations. In August 2019, the 2018 Convertible Note Automatic Conversion Rights were exercised, and the fair value of these rights was reduced to zero. The Series B redeemable convertible preferred stock warrants also qualified as liabilities as the underlying preferred shares were contingently redeemable upon occurrence of a change in control, which is outside the control of the Company. The warrants and 2018 Convertible Note Automatic Conversion Rights were recorded at their fair values upon issuance of $1,421 thousand and $9 thousand, respectively, with the convertible note valued at the residual value of the proceeds. The value of the warrants and 2018 Convertible Note Automatic Conversion Rights totaled $1,430 thousand. That discount was amortized over the expected period of the notes through interest expense using the effective interest method. For the year ended December 31, 2019, $543 thousand of interest expense was recognized for amortization of this discount. The convertible notes payable was presented net of debt issuance costs totaling $72 thousand. These costs were amortized over the expected period of the notes through interest expense using the effective interest method. For the year ended December 31, 2019, $27 thousand of interest expense was recognized for amortization of these costs.

Commitments and Contingencies

Commitments and Contingencies	5 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2020	Sep. 30, 2021	Dec. 31, 2020
Commitments and Contingencies		5. COMMITMENTS AND CONTINGENCIES The Company, from time to time, is made a party to various claims, legal actions, and complaints arising in the ordinary course of business. The Company is not aware of any legal proceedings or other claims, legal actions, or complaints through the date of issuance of these financial statements. On November 1, 2017, the Company executed a standby letter of credit with First Republic Bank totaling $725 thousand for security of its operating lease of office and manufacturing space in Wilsonville, Oregon. The letter of credit is fully secured by restricted certificate of deposit accounts. The Company can draw $200 thousand on the 95 th th The Company purchases materials from several suppliers and has entered into agreements with various contract manufacturers, which include cancelable and noncancelable purchase commitments. As of September 30, 2021, and December 31, 2020, total unfulfilled noncancelable purchase commitments were $13,392 thousand and $3,410 thousand, respectively. In addition, total unfulfilled cancellable purchase commitments amounted to $3,774 thousand and $787 thousand as of September 30, 2021 and December 31, 2020, respectively. These purchase commitments were not recorded in the condensed financial statements.	9. COMMITMENTS AND CONTINGENCIES The Company, from time to time, is a party to various claims, legal actions, and complaints arising in the ordinary course of business. The Company is not aware of any legal proceedings or other claims, legal actions, or complaints through the date of issuance of these financial statements. As of December 31, 2020, and 2019, the Company had a standby letter of credit with First Republic Bank totaling $725 thousand for security of their operating lease of office and manufacturing space in Wilsonville, Oregon. The letter of credit is fully secured by restricted certificate of deposit accounts. There were no draws against the letter of credit during the years ended December 31, 2020 and 2019. The Company purchases materials from several suppliers and has entered into agreements with various contract manufacturers, which include cancelable and noncancelable purchase commitments. As of December 31, 2020, and 2019, total unfulfilled noncancelable purchase commitments were $3,410 thousand and $2,125 thousand, respectively. In addition, total unfulfilled cancellable purchase commitments amounted to $787 thousand and $225 thousand as of December 31, 2020, and 2019, respectively. These purchase commitments were not recorded in the financial statements.
ACON S2 Acquisition Corp [Member]
Commitments and Contingencies	Note 7—Commitments and Contingencies Registration and Shareholder Rights The holders of the Founder Shares, Private Placement Warrants and any warrants that may be issued upon conversion of Working Capital Loans (and any Class A ordinary shares issuable upon the exercise of the Private Placement Warrants and warrants that may be issued upon conversion of Working Capital Loans) are entitled to registration rights pursuant to a registration and shareholder rights agreement. The holders of these securities are entitled to make up to three demands, excluding short form demands, that the Company registers such securities. In addition, the holders have certain “piggy-back” registration rights with respect to registration statements filed subsequent to the completion of the initial Business Combination. The Company will bear the expenses incurred in connection with the filing of any such registration statements. Underwriting Agreement The Company granted the underwriters a 45-day option The underwriters were entitled to an underwriting discount of $0.20 per unit, or $5.0 million in the aggregate, paid upon the closing of the Initial Public Offering. In addition, $0.35 per unit, or approximately $8.8 million in the aggregate will be payable to the underwriters for deferred underwriting commissions. The deferred fee will become payable to the underwriters from the amounts held in the Trust Account solely in the event that the Company completes a Business Combination, subject to the terms of the underwriting agreement. Legal fees The Company obtained legal advisory services, pursuant to which the legal counsel agreed to defer fees until the closing of a Business Combination. As of December 31, 2020, the Company has incurred approximately $490,000 in legal fees.	Note 7 - Registration and Shareholder Rights The holders of the Founder Shares, Private Placement Warrants and any warrants that may be issued upon conversion of Working Capital Loans (and any Class A ordinary shares issuable upon the exercise of the Private Placement Warrants and warrants that may be issued upon conversion of Working Capital Loans) are entitled to registration rights pursuant to a registration and shareholder rights agreement. The holders of these securities are entitled to make up to three demands, excluding short form demands, that the Company registers such securities. In addition, the holders have certain “piggy-back” registration rights with respect to registration statements filed subsequent to the completion of the initial business combination. The Company will bear the expenses incurred in connection with the filing of any such registration statements. Underwriting Agreement The underwriters were entitled to an underwriting discount of $0.20 per unit, or $5.0 million in the aggregate, paid upon the closing of the Initial Public Offering. In addition, $0.35 per unit, or approximately $8.8 million in the aggregate will be payable to the underwriters for deferred underwriting commissions. The deferred fee will become payable to the underwriters from the amounts held in the Trust Account solely in the event that the Company completes a business combination, subject to the terms of the underwriting agreement.

Class A Ordinary Shares Subject

Class A Ordinary Shares Subject to Possible Redemption	5 Months Ended	9 Months Ended
	Dec. 31, 2020	Sep. 30, 2021
ACON S2 Acquisition Corp [Member]
Class A Ordinary Shares Subject to Possible Redemption	Note 8—Class A Ordinary Shares Subject to Possible Redemption The Company’s Class A ordinary shares feature certain redemption rights that are considered to be outside of the Company’s control and subject to the occurrence of future events. The Company is authorized to issue 500,000,000 Class A ordinary shares with a par value of $0.0001 per share. Holders of the Company’s Class A ordinary shares are entitled to one vote for each share. As of December 31, 2020, there were 25,000,000 Class A ordinary shares outstanding, all of which were subject to possible redemption and classified outside of permanent equity in the condenses balance sheets. The Class A ordinary shares issued in the Initial Public Offering were recognized in Class A ordinary shares subject to possible redemption as recorded outside of permanent equity as follows: Gross Proceeds $ 250,000,000 Less: Offering costs allocated to Class A shares subject to possible redemption (13,646,752 ) Proceeds allocated to Public Warrants at issuance (12,500,000 ) Plus: Remeasurement adjustment on Class A ordinary shares subject to possible redemption 26,146,752 Class A ordinary shares subject to possible redemption $ 250,000,000	Note 8 - The Company’s Class A ordinary shares feature certain redemption rights that are considered to be outside of the Company’s control and subject to the occurrence of future events. The Company is authorized to issue 500,000,000 Class A ordinary shares with a par value of $0.0001 per share. Holders of the Company’s Class A ordinary shares are entitled to one vote for each share. As of September 30, 2021, there were 25,000,000 Class A ordinary shares outstanding, all of which were subject to possible redemption and classified outside of permanent equity in the condenses balance sheets. The Class A ordinary shares issued in the Initial Public Offering were recognized in Class A ordinary shares subject to possible redemption as recorded outside of permanent equity as follows: Gross Proceeds $ 250,000,000 Less: — Offering costs allocated to Class A shares subject to possible redemption (13,646,752 ) Proceeds allocated to Public Warrants at issuance (12,500,000 ) Plus: Remeasure adjustment on Class A ordinary shares subject to possible redemption amount 26,146,752 Class A ordinary shares subject to possible redemption $ 250,000,000

Shareholders' Equity

Shareholders' Equity	5 Months Ended	9 Months Ended
	Dec. 31, 2020	Sep. 30, 2021
ACON S2 Acquisition Corp [Member]
Shareholders' Equity	Note 9—Shareholders’ Equity Class A Ordinary Shares Class B Ordinary Shares Ordinary shareholders of record are entitled to one vote for each share held on all matters to be voted on by shareholders. Except as described below, holders of Class A ordinary shares and holders of Class B ordinary shares will vote together as a single class on all matters submitted to a vote of the shareholders except as required by law. The Class B ordinary shares will automatically convert into Class A ordinary shares (which such Class A ordinary shares delivered upon conversion will not have redemption rights or be entitled to liquidating distributions from the Trust Account if the Company does not consummate an initial business combination) at the time of the initial Business Combination or earlier at the option of the holders thereof at a ratio such that the number of Class A ordinary shares issuable upon conversion of all Founder Shares will equal, in the aggregate, on an as-converted basis, than one-to-one. Preference Shares time to time by the Company’s board of directors. As of December 31, 2020, there were no preference shares issued or outstanding.	Note 9 - Preference Shares Class A Ordinary Shares Class B Ordinary Shares no Ordinary shareholders of record are entitled to one vote for each share held on all matters to be voted on by shareholders. Except as described below, holders of Class A ordinary shares and holders of Class B ordinary shares will vote together as a single class on all matters submitted to a vote of the shareholders except as required by law. The Class B ordinary shares will automatically convert into Class A ordinary shares (which such Class A ordinary shares delivered upon conversion will not have redemption rights or be entitled to liquidating distributions from the Trust Account if the Company does not consummate an initial business combination) at the time of the initial business combination or earlier at the option of the holders thereof at a ratio such that the number of Class A ordinary shares issuable upon conversion of all Founder Shares will equal, in the aggregate, on an as-converted completion of the Initial Public Offering, plus (ii) the total number of Class A ordinary shares issued or deemed issued or issuable upon conversion or exercise of any equity-linked securities or rights issued or deemed issued, by the Company in connection with or in r one-to-one.

Derivative Warrant Liabilities

Derivative Warrant Liabilities	5 Months Ended	9 Months Ended
	Dec. 31, 2020	Sep. 30, 2021
ACON S2 Acquisition Corp [Member]
Derivative Warrant Liabilities	Note 10—Derivative Warrant Liabilities As of December 31, 2020, the Company has 8,333,333 and 4,666,667 Public Warrants and Private Placement Public Warrants may only be exercised for a whole number of shares. No fractional Public Warrants will be issued upon separation of the Units and only whole Public Warrants will trade. The Public Warrants will become exercisable on the later of (a) 30 days after the completion of a Business Combination or (b) 12 months from the closing of the Initial Public Offering; provided in each case that the Company has an effective registration statement under the Securities Act covering the Class A ordinary shares issuable upon exercise of the Public Warrants and a current prospectus relating to them is available and such shares are registered, qualified or exempt from registration under the securities, or blue sky, laws of the state of residence of the holder (or the Company permit holders to exercise their warrants on a cashless basis under certain circumstances). The Company has agreed that as soon as practicable, but in no event later than twenty (20) business days after the closing of the initial Business Combination, the Company will use commercially reasonable efforts to file with the SEC and have an effective registration statement covering the Class A ordinary shares issuable upon exercise of the warrants and to maintain a current prospectus relating to those Class A ordinary shares until the warrants expire or are redeemed, as specified in the warrant agreement. If a registration statement covering the Class A ordinary shares issuable upon exercise of the warrants is not effective by the 60th day after the closing of the initial Business Combination, warrant holders may, until such time as there is an effective registration statement and during any period when the Company will have failed to maintain an effective registration statement, exercise warrants on a “cashless basis” in accordance with Section 3(a)(9) of the Securities Act or another exemption. Notwithstanding the above, if the Class A ordinary shares are at the time of any exercise of a warrant not listed on a national securities exchange such that they satisfy the definition of a “covered security” under Section 18(b)(1) of the Securities Act, the Company may, at its option, require holders of Public Warrants who exercise their warrants to do so on a “cashless basis” and, in the event the Company so elects, the Company will not be required to file or maintain in effect a registration statement, and in the event the Company does not so elect, it will use commercially reasonable efforts to register or qualify the shares under applicable blue sky laws to the extent an exemption is not available. The warrants have an exercise price of $11.50 per share, subject to adjustments, and will expire five years after the completion of a Business Combination or earlier upon redemption or liquidation. In addition, if (x) the Company issues additional Class A ordinary shares or equity-linked securities for capital raising purposes in connection with the closing of the initial Business Combination at an issue price or effective issue price of less than $9.20 per ordinary share (with such issue price or effective issue price to be determined in good faith by the board of directors and, in the case of any such issuance to our Sponsor or its affiliates, without taking into account any Founder Shares held by our Sponsor or such affiliates, as applicable, prior to such issuance) (the “Newly Issued Price”), (y) the aggregate gross proceeds from such issuances represent more than 60% of the total equity proceeds, and interest thereon, available for the funding of the initial Business Combination on the date of the consummation of the initial Business Combination (net of redemptions), and (z) the volume weighted average trading price of the Class A ordinary shares during the 20 trading day period starting on the trading day prior to the day on which the Company consummates its initial business Combination (such price, the “Market Value”) is below $9.20 per share, the exercise price of the warrants will be adjusted (to the nearest cent) to be equal to 115% of the higher of the Market Value and the Newly Issued Price, and the $18.00 per share redemption trigger price will be adjusted (to the nearest cent) to be equal to 180% of the higher of the Market Value and the Newly Issued Price, and the $10.00 per share redemption trigger price will be adjusted (to the nearest cent) to be equal to the higher of the Market Value and the Newly Issued Price. The Private Placement Warrants are identical to the Public Warrants underlying the Units sold in the Initial Public Offering, except that the Private Placement Warrants and the Class A ordinary shares issuable upon exercise of the Private Placement Warrants will not be transferable, assignable or salable until 30 days after the completion of a Business Combination, subject to certain limited exceptions. Additionally, the Private Placement Warrants will be non-redeemable so Redemption of warrants when the price per Class A ordinary share equals or exceeds $18.00: • in whole and not in part; • at a price of $0.01 per warrant; • upon a minimum of 30 days’ prior written notice of redemption to each warrant holder; and • if, and only if, the last reported sale price (the “closing price”) of Class A ordinary shares equals or exceeds $18.00 per share (as adjusted) for any 20 trading days within a 30-trading day The Company will not redeem the warrants as described above unless an effective registration statement under the Securities Act covering the Class A ordinary shares issuable upon exercise of the warrants is effective and a current prospectus relating to those Class A ordinary shares is available throughout the 30-day redemption Redemption of warrants when the price per Class A ordinary share equals or exceeds $10.00: • in whole and not in part; • at $0.10 per warrant upon a minimum of 30 days’ prior written notice of redemption provided • if, and only if, the closing price of Class A ordinary shares equals or exceeds $10.00 per Public Share (as adjusted) for any 20 trading days within the 30-trading day • if the closing price of the Class A ordinary shares for any 20 trading days within a 30-trading day The “fair market value” of Class A ordinary shares for the above purpose shall mean the volume weighted average price of Class A ordinary shares during the 10 trading days immediately following the date on which the notice of redemption is sent to the holders of warrants. In no event will the warrants be exercisable in connection with this redemption feature for more than 0.361 Class A ordinary shares per warrant (subject to adjustment). In no event will the Company be required to net cash settle any warrant. If the Company is unable to complete a Business Combination within the Combination Period and the Company liquidates the funds held in the Trust Account, holders of warrants will not receive any of such funds with respect to their warrants, nor will they receive any distribution from the Company’s assets held outside of the Trust Account with the respect to such warrants. Accordingly, the warrants may expire worthless.	Note 10 - As of September 30, 2021, there were 13,000,000 total warrants outstanding, of which the Company has 8,333,333 and 4,666,667 Public Warrants and Private Placement Warrants, respectively. Public Warrants may only be exercised for a whole number of shares. No fractional Public Warrants will be issued upon separation of the Units and only whole Public Warrants will trade. The Public Warrants will become exercisable on the later of (a) 30 days after the completion of a business combination or (b) 12 months from the closing of the Initial Public Offering; provided in each case that the Company has an effective registration statement under the Securities Act covering the Class A ordinary shares issuable upon exercise of the Public Warrants and a current prospectus relating to them is available and such shares are registered, qualified or exempt from registration under the securities, or blue sky, laws of the state of residence of the holder (or the Company permit holders to exercise their warrants on a cashless basis under certain circumstances). The Company has agreed that as soon as practicable, but in no event later than twenty (20) business days after the closing of the initial business combination, the Company will use commercially reasonable efforts to file with the SEC and have an effective registration statement covering the Class A ordinary shares issuable upon exercise of the warrants and to maintain a current prospectus relating to those Class A ordinary shares until the warrants expire or are redeemed, as specified in the warrant agreement. If a registration statement covering the Class A ordinary shares issuable upon exercise of the warrants is not effective by the 60th day after the closing of the initial business combination, warrant holders may, until such time as there is an effective registration statement and during any period when the Company will have failed to maintain an effective registration statement, exercise warrants on a “cashless basis” in accordance with Section 3(a)(9) of the Securities Act or another exemption. Notwithstanding the above, if the Class A ordinary shares are at the time of any exercise of a warrant not listed on a national securities exchange such that they satisfy the definition of a “covered security” under Section 18(b)(1) of the Securities Act, the Company may, at its option, require holders of Public Warrants who exercise their warrants to do so on a “cashless basis” and, in the event the Company so elects, the Company will not be required to file or maintain in effect a registration statement, and in the event the Company does not so elect, it will use commercially reasonable efforts to register or qualify the shares under applicable blue sky laws to the extent an exemption is not available. The warrants have an exercise price of $11.50 per share, subject to adjustments, and will expire five years after the completion of a business combination or earlier upon redemption or liquidation. In addition, if (x) the Company issues additional Class A ordinary shares or equity-linked securities for capital raising purposes in connection with the closing of the initial business combination at an issue price or effective issue price of less than $9.20 per ordinary share (with such issue price or effective issue price to be determined in good faith by the board of directors and, in the case of any such issuance to our Sponsor or its affiliates, without taking into account any Founder Shares held by our Sponsor or such affiliates, as applicable, prior to such issuance) (the “Newly Issued Price”), (y) the aggregate gross proceeds from such issuances represent more than 60% of the total equity proceeds, and interest thereon, available for the funding of the initial business combination on the date of the consummation of the initial business combination (net of redemptions), and (z) the volume weighted average trading price of the Class A ordinary shares during the 20 trading day period starting on the trading day prior to the day on which the Company consummates its initial business combination (such price, the “Market Value”) is below $9.20 per share, the exercise price of the warrants will be adjusted (to the nearest cent) to be equal to 115% of the higher of the Market Value and the Newly Issued Price, and the $18.00 per share redemption trigger price will be adjusted (to the nearest cent) to be equal to 180% of the higher of the Market Value and the Newly Issued Price, and the $10.00 per share redemption trigger price will be adjusted (to the nearest cent) to be equal to the higher of the Market Value and the Newly Issued Price. The Private Placement Warrants are identical to the Public Warrants underlying the Units sold in the Initial Public Offering, except that the Private Placement Warrants and the Class A ordinary shares issuable upon exercise of the Private Placement Warrants will not be transferable, assignable or salable until 30 days after the completion of a business combination, subject to certain limited exceptions. Additionally, the Private Placement Warrants will be non-redeemable Redemption of warrants when the price per Class A ordinary share equals or exceeds $18.00: Once the warrants become exercisable, the Company may call the outstanding warrants for redemption (except as described herein with respect to the Private Placement Warrants): • in whole and not in part; • at a price of $0.01 per warrant; • upon a minimum of 30 days’ prior written notice of redemption to each warrant holder; and • if, and only if, the last reported sale price (the “closing price”) of Class A ordinary shares equals or exceeds $18.00 per share (as adjusted) for any 20 trading days within a 30-trading The Company will not redeem the warrants as described above unless an effective registration statement under the Securities Act covering the Class A ordinary shares issuable upon exercise of the warrants is effective and a current prospectus relating to those Class A ordinary shares is available throughout the 30-day Redemption of warrants when the price per Class A ordinary share equals or exceeds $10.00: Once the warrants become exercisable, the Company may redeem the outstanding warrants: • in whole and not in part; • at $0.10 per warrant upon a minimum of 30 days’ prior written notice of redemption provided • if, and only if, the closing price of Class A ordinary shares equals or exceeds $10.00 per Public Share (as adjusted) for any 20 trading days within the 30-trading • if the closing price of the Class A ordinary shares for any 20 trading days within a 30-trading The “fair market value” of Class A ordinary shares for the above purpose shall mean the volume weighted average price of Class A ordinary shares during the 10 trading days immediately following the date on which the notice of redemption is sent to the holders of warrants. In no event will the warrants be exercisable in connection with this redemption feature for more than 0.361 Class A ordinary shares per warrant (subject to adjustment). In no event will the Company be required to net cash settle any warrant. If the Company is unable to complete a business combination within the Combination Period and the Company liquidates the funds held in the Trust Account, holders of warrants will not receive any of such funds with respect to their warrants, nor will they receive any distribution from the Company’s assets held outside of the Trust Account with the respect to such warrants. Accordingly, the warrants may expire worthless.

Redeemable Convertible Preferre

Redeemable Convertible Preferred Stock	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Temporary Equity Disclosure [Abstract]
Redeemable Convertible Preferred Stock	6. REDEEMABLE CONVERTIBLE PREFERRED STOCK On May 7, 2021, the Company amended and restated its Certificate of Incorporation (the “Fifth Restatement”). The Fifth Restatement supersedes and replaces all previous Certificates of Incorporation. Under the Fifth Restatement, the Company is authorized to issue 79,000,000 shares of common stock with $0.0001 par value. The holders of common stock are entitled to one vote for each share held. Under the Fifth Restatement, the number of shares of preferred stock authorized for issuance remained the same at 62,072,064 with $0.0001 par value. The Company’s Redeemable Convertible Preferred Stock as of September 30, 2021 consisted of the following (in thousands, except share data): Shares Shares Issued and Issuance Net Carrying Aggregate Series A 5,941,109 5,941,109 $ 0.56 $ 3,228 $ 3,321 Series B 12,011,923 12,005,442 1.23 30,659 14,748 Series C-1 16,345,688 16,335,705 1.84 19,178 30,098 Series C-2 27,773,344 4,486,133 2.95 37,008 13,225 62,072,064 38,768,389 $ 90,073 $ 61,392 Sale of Series C-2 In March 2021, the Company issued 3,900,988 shares of Series C-2 C-2 C-2 C-2 C-2 C-2 Amendment to Series C-2 On May 7, 2021, the Company amended its Series C-2 C-2 C-2 C-2 C-2 C-2 C-2 C-2 As of September 30, 2021 Quantity Price Proceeds Series C-2 23,236,328 $ 2.95 $ 68,499,998 As of September 30, 2021 Upon Completion of SPAC merger Quantity Price Proceeds Series C-2 5,427,464 $ 2.95 $ 16,000,000 Series C-2 14,365,207 0.0001 1,437 Total Proceeds Upon Exercise $ 16,001,437 As of September 30, 2021 Milestones without SPAC merger Quantity Price Proceeds Series C-2 22,897,111 $ 2.95 $ 67,499,996 The Series C-2 C-2 C-2 C-2 C-2 Warrants The Company periodically issues warrants in conjunction with the issuance of preferred stock or debt. As of September 30, 2021, and December 31, 2020, the following warrants were outstanding: September 30, December 31, Common Stock Warrants — 305,611 Series B Preferred Warrants — 1,362,771 Series C Preferred Warrants — 70,000 Total Warrants — 1,738,382 The outstanding warrants include Series C redeemable convertible preferred stock warrants and Series B redeemable convertible preferred stock warrants issued in conjunction with the Company’s long-term debt discussed within Note 4. The table of warrants outstanding above, does not include the 14,365,207 Series C-2 C-2 The Company’s Series B redeemable convertible preferred stock warrants and Series C redeemable convertible preferred stock warrants were liability classified awards. The 0.001 1.42 68,000 ten-year 1,290,777 The Company’s Series C-1 C-2 The common stock warrants, all issued at a price of $0.001 per share, were recorded at fair value within equity. The common stock warrants were fully vested at issuance and do not expire until a significant transaction has occurred, as defined by the Warrant Purchase Agreement. The table below shows the warrant activities during the nine months ended September 30, 2021: December 31, Issued Exercised September 30, Common Stock Warrants 305,611 — 305,611 — Series B Preferred Stock Warrants 1,362,771 — 1,362,771 — Series C Preferred Stock Warrants 70,000 585,145 655,145 — Total Warrants 1,738,382 585,145 2,323,527 — The table below shows the valuation assumptions for the warrants immediately prior to the exercises as of and for the nine months ended September 30, 2021: As of and for nine months ended September 30, 2021 Common Series B Series C-1 Series C-2 Expected volatility N/A 80% 80% 80% Expected term (in years) N/A 2 2 2 Risk-free interest rate N/A 0.16% - 0.28% 0.16% - 0.28% 0.16% - 0.28% Dividend yield N/A 0% 0% 0% The warrants were valued using the following assumptions as of December 31, 2020: As of December 31, 2020 Common Series B Series C-1 Series C-2 Expected volatility N/A 80 % 80 % N/A Expected term (in years) N/A 2 2 N/A Risk-free interest rate N/A 0.13 % 0.13 % N/A Dividend yield N/A 0 % 0 % N/A	10. REDEEMABLE CONVERTIBLE PREFERRED STOCK The Company amended and restated its certificate of incorporation effective August 27, 2019 (the “Third Restatement”). This Third Amended and Restated Certificate of Incorporation replaced the Second Amended and Restated Certificate of Incorporation that was in effect in 2018 and 2019 prior to August 27, 2019 (the “Second Restatement”). The Third Restatement authorized the Company to issue Series C redeemable convertible preferred stock. The authorization and addition of Series C redeemable convertible preferred stock was the only significant change to the Amended and Restated Certificate of Incorporation. Redeemable Convertible Preferred Stock and Warrants The Company’s Redeemable Convertible Preferred Stock as of December 31, 2020 consisted of (in thousands, except share data): Shares Shares Issued Issuance Net Carrying Aggregate Series A 5,941,109 5,941,109 $ 0.56 $ 3,228 $ 3,321 Series B 12,011,923 10,649,152 1.22848 12,746 13,082 Series C- 16,345,688 16,275,688 1.84248 18,398 29,988 Series C- 27,137,317 — — — — 61,436,037 32,865,949 $ 34,372 $ 46,391 Under the Third Restatement, dividends accrue, if and when declared by the Board, on the preferred stock at a rate of $0.044725 per share of Series A, $0.09828 per share of Series B, $0.14740 per share of Series C-1 C-2. non-cumulative Liquidation Preferences In the event of any liquidation, dissolution, or winding-up After payment of the Liquidation Preference to the holders of preferred stock, the remaining assets of the Company shall be distributed ratably to the holders of common stock on a fully converted basis. Voting Rights Each holder of each outstanding share of Preferred stock shall be entitled to cast the number of votes equal to the number of whole shares of common stock into which the shares of Preferred stock could be converted as of the date of the vote. Conversion Rights Each share of preferred stock is convertible, at the option of the holder, into the number of shares of Common stock determined by dividing the original issue price for the relevant series by the conversion price for such series. Redemption Rights Series B redeemable convertible preferred stock were redeemable at any time, at the option of the holder, after the fifth two thirds All classes of preferred stock and warrants are not redeemable by the holder except in the event of acquisition, merger, consolidation, or the sale, lease, transfer, exclusive license, or other disposition by the Company or any subsidiary of all or substantially all of the assets of the Company. These events are outside the control of the Company, and therefore the preferred stock have been classified in the mezzanine section of balance sheets. Future Rights to Purchase Series C-2 The Company’s Series C redeemable convertible preferred stock financing agreement provides additional committed funding of up to $79,999 thousand, through the purchase of up to 27,137,000 shares of Series C-2 C-1 The Company determined that its obligation to issue, and the Company’s investors’ obligation to purchase shares of Series C-2 C-2 C-2 C-2 The Series C-2 C-2 Warrants The Company periodically issues warrants in conjunction with the issuance of preferred stock or debt. As of December 31, the following warrants were outstanding: 2020 2019 Common Stock Warrants 305,611 305,611 Series B Preferred Warrants 1,362,771 1,362,771 Series C Preferred Warrants 70,000 — Total Warrants 1,738,382 1,668,382 The outstanding warrants include Series B redeemable convertible preferred stock warrants issued in the Series B redeemable convertible preferred issuance as well as in conjunction with the Company’s long-term debt, and Series C redeemable convertible preferred stock warrants issued in conjunction with the Company’s long-term debt discussed within Note 8. The Company’s Series B redeemable convertible preferred stock warrants and Series C redeemable convertible preferred stock warrants are liability awards. Refer to Note 13. The Company’s Series B redeemable convertible preferred stock warrants were issued at exercise prices ranging from $0.001 per share to $1.22 per share. 68,000 shares of Series B redeemable convertible preferred stock warrants have a ten-year exercise period and the remainder do not expire until a significant transaction has occurred, as defined by the warrant purchase agreement. The warrants were fully vested at the issuance date. The Company’s Series C redeemable convertible preferred stock warrants were issued with a price of $1.84 per share, a life of 10 years and were fully vested at issuance. The common stock warrants, all issued at a price of $0.001 per share, are recorded at fair value within equity when they were issued in conjunction with the Series B preferred stock issuance. The common stock warrants are fully vested at issuance and do not expire until a significant transaction has occurred, as defined by the warrant purchase agreement. The warrants were valued using the following assumptions: At issuance date Common Preferred B Preferred C-1 Expected volatility 80 % 80 % 80 % Expected term (in years) 5.00 5.00 3.75 Risk-free interest rate 2.20 % 2.20 - 2.73 % 0.29 % Dividend yield 0 % 0 % 0 % As of December 31, 2020 Common Preferred B Preferred C-1 Expected volatility N/A 80 % 80 % Expected term (in years) N/A 2.00 2.00 Risk-free interest rate N/A 0.13 % 0.13 % Dividend yield N/A 0 % 0 % As of December 31, 2019 Common Preferred B Preferred C-1 Expected volatility N/A 80 % 80 % Expected term (in years) N/A 4.00 4.00 Risk-free interest rate N/A 1.66 % 1.66 % Dividend yield N/A 0 % 0 %

Common Stock

Common Stock	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Common Stock	11. COMMON STOCK Under the Third Restatement, the Company is authorized to issue 79,000,000 shares of common stock with $0.0001 par value. The holders of common stock are entitled to one vote for each share held.

Stock-based Compensation Plan

Stock-based Compensation Plan	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Share-based Payment Arrangement [Abstract]
Stock-based Compensation Plan	7. STOCK-BASED COMPENSATION PLAN The Company has a 2014 Equity Incentive Plan (the “Plan”) under which it has authorized 10,524,556 shares of common stock to be reserved for grants or sale. The stock awards may be issued as Incentive Stock Options (“ISO”), Non-statutory No Stock Appreciation Rights, Restricted Stock Awards, or Restricted Stock Unit Awards are outstanding as of September 30, 2021 and December 31, 2020. Option prices for ISOs are normally set at not less than the fair market value of the Company’s common stock at the date of grant. Employee options generally cliff vest at the end of the first year and then 1/ 48 th A summary of options outstanding under the Plan as of September 30, 2021 and changes during the nine months ended September 30, 2021 is presented below: Options Outstanding Number of Weighted Weighted Aggregate Balances as of December 31, 2020 3,891,768 $ 0.44 8.23 $ 4,333 Granted 987,500 $ 2.57 Exercised (1,685,675 ) $ 0.40 Forfeited (400,938 ) $ 0.69 Balances as of September 30, 2021 2,792,655 $ 1.18 8.53 $ 30,331 Options vested and exercisable - September 30, 2021 702,291 $ 0.44 3.37 $ 8,150 In accordance with Accounting Standards Codification (ASC) 718, the fair value of each option grant has been estimated as of the date of grant using the Black-Scholes Merton option-pricing model based on the following weighted average assumptions: Nine Months Ended 2021 2020 Risk-free rate 1.01 % 1.12 % Expected dividends — — Expected term 6 years 6 years Expected volatility 75 % 70 % The compensation expense is allocated on a departmental basis, based on the classification of the award holder. The following table presents the amount of stock-based compensation related to stock-based awards to employees on the Company’s Statements of Operations and Other Comprehensive Loss (in thousands): Nine Months Ended 2021 2020 Research and development $ 223 $ 54 Sales and marketing 48 33 General and administrative 349 164 Total stock-based compensation $ 620 $ 251	12. STOCK-BASED COMPENSATION PLAN The Company has a 2014 Equity Incentive Plan (the “Plan”) under which it has authorized 10,524,556 shares of common stock to be reserved for grants or sale. The stock awards may be issued as Incentive Stock Options (ISO), Non-statutory Stock Options (NSO), Stock Appreciation Rights, Restricted Stock Awards, or Restricted Stock Unit Awards. Only employees are eligible to receive ISO awards. Employees, directors, and consultants who are providing continuous service to the Company are eligible to receive stock awards other than ISOs. No Stock Appreciation Rights, Restricted Stock Awards, or Restricted Stock Unit Awards are outstanding as of December 31, 2020 and 2019. Option prices for incentive stock options are normally set at not less than the fair market value of the Company’s common stock at the date of grant. Employee option grants generally cliff vest twenty-five 48 th Shares Available for Future Grant 2020 2019 Shares Available for future grant 5,993,465 7,855,010 The Company issues new shares upon a share option exercise or release. A summary of option activity under the Plan as of December 31, 2020 and 2019 and changes during the years ended December 31, 2020 and 2019 is presented below: Options Outstanding Number of Weighted Weighted Aggregate Balances as of December 31, 2018 2,238,598 $ 0.37 8.83 $ 332 Granted 17,500 $ 0.45 Exercised (30,000) $ 0.22 Forfeited (121,875) $ 0.45 Balances as of December 31, 2019 2,104,223 $ 0.37 7.82 $ 821 Granted 2,221,278 $ 0.49 Exercised (74,000) $ 0.09 Forfeited (359,733) $ 0.43 Balances as of December 31, 2020 3,891,768 $ 0.44 8.23 $ 4,333 Options vested and exercisable - December 31, 2019 1,424,380 $ 0.34 7.48 $ 604 Options vested and exercisable - December 31, 2020 1,918,067 $ 0.39 7.21 $ 2,215 The aggregate intrinsic value is the fair market value on the reporting date less the exercise price for each option. The aggregate intrinsic value of the options exercised was $48 thousand and $9 thousand during the years ended December 31, 2020 and 2019, respectively. The fair value of each stock option award is estimated on the date of the grant using the Black-Scholes Merton option-pricing model. For options granted during the years ended December 31, 2020, and 2019, respectively, the weighted average estimated fair value using the Black-Scholes Merton option pricing model was $0.65 and $0.36 per option, respectively. In accordance with ASC 718, the fair value of each option grant has been estimated as of the date of grant using the following weighted average assumptions: 2020 2019 Risk-free rate 0.93 % 2.63 % Expected dividends — — Expected term 6 years 6 years Expected volatility 71.06 % 76.77 % The compensation expense is allocated on a departmental basis, based on the classification of the award holder. The following table presents the amount of stock-based compensation related to stock-based awards to employees on the Company’s statements of loss during the years ended December 31, 2020 and 2019 (in thousands): 2020 2019 Research and development $ 79 $ 59 Sales and marketing 47 38 General and administrative 184 78 Total stock-based compensation $ 310 $ 175 As of December 31, 2020, there was approximately $1,193 thousand of unamortized stock-based compensation cost related to unvested stock options, which is expected to be recognized over a weighted average period of 2.5 years.

Fair Value Measurements

Fair Value Measurements	5 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2020	Sep. 30, 2021	Dec. 31, 2020
Fair Value Measurements		8. FAIR VALUE MEASUREMENTS The Company’s fair value hierarchy for its financial assets and liabilities measured at fair value on a recurring basis are as follows (in thousands): September 30, 2021 Level 1 Level 2 Level 3 Total Assets: Cash equivalents and restricted cash: Money market funds $ 6,986 $ — $ — $ 6,986 Certificate of deposit — 75 — 75 Total Assets $ 6,986 $ 75 $ — $ 7,061 Liabilities: Bridge loan $ — $ — $ 21,432 $ 21,432 Derivative liabilities — — 248,450 248,450 Warrant liabilities — — — — Total Liabilities $ — $ — $ 269,882 $ 269,882 December 31, 2020 Assets: Cash equivalents and restricted cash: Money market funds $ 3,046 $ — $ — $ 3,046 Certificate of deposit — 326 — 326 Total Assets $ 3,046 $ 326 $ — $ 3,372 Liabilities: Bridge loan $ — $ — $ — $ — Derivative liabilities — — 22,911 22,911 Warrant liabilities — — $ 3,329 3,329 Total Liabilities $ — $ — $ 26,240 $ 26,240 For the three and nine months ended September 30, 2021 and 2020, there were no transfers between levels in the fair value hierarchy. The carrying amounts of the Company’s notes payable and accounts payable approximate their fair values due to their short maturities. Level 1 Assets: The Company invests in money market funds that have maturities of 90 days or less. The money market funds are classified as cash equivalents and are recorded at their carrying value, which approximates fair value. Level 2 Assets: The Company invests in a certificate of deposit with a maturity of one year from purchase date. The certificate of deposit is classified as restricted cash and recorded at its carrying value, which approximates fair value. Level 3 Liabilities: Bridge Loan The Company accounts for the Bridge Loan under the fair value option election wherein the Bridge Loan is initially measured at its issue-date fair value and then subsequently re-measured The fair value of the Bridge Loan is based on significant inputs including, estimated time to maturity, which causes them to be classified as a Level 3 measurement within the fair value hierarchy. The valuation uses assumptions and estimates the Company believes would be made by a market participant in making the same valuation. The Bridge Loan was paid off on October 8, 2021 as part of the SPAC merger. See Note 10 for further details. Warrants Freestanding warrants to purchase Redeemable Convertible Preferred Stock are accounted for as liability awards and recorded at fair value on their issuance date and adjusted to fair value at each reporting date, with the change in fair value being recorded as a component of other income (expense). The warrants are accounted for as liabilities as the underlying shares of Preferred Stock are contingently redeemable upon occurrence of a change in control, which is outside the control of the Company. The Company measures its warrant liabilities using Level 3 unobservable inputs within the Black-Scholes Merton option-pricing model. The Company uses various key assumptions, such as the fair value of Series B redeemable convertible preferred stock warrants and Series C redeemable convertible preferred stock warrants, the volatility of peer companies’ stock prices, the risk-free interest rate based on the U.S. Treasury yield, and the expected term (based on remaining term to a significant event for Series B redeemable convertible preferred stock warrants and remaining contractual term for Series C redeemable convertible preferred stock warrants). The Company measures the fair value of the redeemable convertible Preferred Stock warrants at each reporting date, with subsequent gains and losses from remeasurement of Level 3 financial liabilities recorded through other expense, net in the Statements of Operations and Comprehensive Loss. All the warrants were exercised during the nine months ended September 30, 2021. Future Rights to Purchase Series C-2 The Company’s Series C Redeemable Convertible Preferred Stock financing agreement provides additional committed funding through the purchase of shares of Series C-2 C-1 C-2 C-2 C-2 The value of the Series C-2 The Company utilized a probability weighting of successful completion of the SPAC merger versus probability of the Company staying private in establishing the quantity of purchase rights to value and the fair value of the Series C-2 C-2 C-2 C-2 C-2 C-2 The following table sets forth a summary of changes in the fair value of the Company’s level 3 liabilities at fair value on a recurring basis (in thousands): Three Months Ended 2021 2020 Bridge loan: Beginning balance June 30 $ — $ — Fair value of Bridge loan funded 20,000 — Accrued PIK and final payment 1,432 — Change in fair value — — Ending balance September 30 21,432 — Warrant liabilities: Beginning balance June 30 22,860 1,979 Change in fair value 2,949 (24 ) Fair value of warrants issued — — Fair value of warrants exercised (25,809 ) — Ending balance September 30 — 1,955 Series C-2 Beginning balance June 30 211,747 7,619 Change in fair value 36,703 (2,089 ) Fair value of derivatives extinguished — — Ending balance September 30 248,450 5,530 Total $ 269,882 $ 7,485 Nine Months Ended 2021 2020 Bridge loan: Beginning balance December 31 $ — $ — Fair value of Bridge loan funded 20,000 — Accrued PIK and final payment 1,432 — Change in fair value — — Ending balance September 30 21,432 — Warrant liabilities: Beginning balance December 31 3,329 1,989 Change in fair value 17,753 (78 ) Fair value of warrants issued 5,096 44 Fair value of warrants exercised (26,178 ) — Ending balance September 30 — 1,955 Series C-2 Beginning balance December 31 22,911 11,379 Change in fair value 248,691 (5,849 ) Fair value of derivatives extinguished (23,152 ) — Ending balance September 30 248,450 5,530 Total $ 269,882 $ 7,485	13. FAIR VALUE MEASUREMENTS The Company follows ASC 820, Fair Value Measurements December 31, 2020 Level 1 Level 2 Level 3 Total Assets: Cash equivalents and restricted cash: Money market funds $ 3,046 $ — $ — $ 3,046 Certificate of deposit — 326 — 326 Total Assets $ 3,046 $ 326 $ — $ 3,372 Liabilities: Derivative liabilities $ — $ — $ 22,911 $ 22,911 Warrant liabilities — — 3,329 3,329 Total Liabilities $ — $ — $ 26,240 $ 26,240 December 31, 2019 Assets: Restricted cash: Certificate of deposit $ — $ 529 $ — $ 529 Total Assets $ — $ 529 $ — $ 529 December 31, 2020 Level 1 Level 2 Level 3 Total Liabilities: Derivative liabilities $ — $ — $ 11,379 $ 11,379 Warrant liabilities — — 1,989 1,989 Total Liabilities $ — $ — $ 13,368 $ 13,368 For fiscal years 2020 and 2019, there were no transfers among Level 1, Level 2, or Level 3 categories. The carrying amounts of the Company’s notes payable, grant receivable and accounts payable approximate their fair values due to their short maturities. Level 1 Assets: The Company invests in money market funds that have maturities of 90 days or less. Money market funds are classified as cash equivalents and are recorded at their carrying value, which approximates fair value. Level 2 Assets: The Company invests in a certificate of deposit with a maturity of one year from purchase date. The certificate of deposit is classified as restricted cash and is recorded at its carrying value, which approximates fair value. Level 3 Liabilities: Warrants Freestanding warrants to purchase redeemable convertible preferred stock are accounted for as liability awards and recorded at fair value on their initial issuance date and adjusted to fair value at each reporting date, with the change in fair value being recorded in the Statement of Operations and Other Comprehensive Income. The warrants are accounted for as liabilities as the underlying preferred shares are contingently redeemable upon occurrence of a change in control, which is outside the control of the Company. The Company measures its warrant liabilities using Level 3 unobservable inputs within the Black-Scholes Merton option-pricing model. The Company uses various key assumptions, such as the fair value of redeemable convertible preferred stock Series B and Series C, the volatility of peer companies’ stock prices, the risk-free interest rate based on the U.S. treasury yield, and the expected term (based on remaining term to a significant event). The Company measures the fair value of the redeemable convertible preferred stock warrants at each reporting date, with subsequent gains and losses from remeasurement of Level 3 financial liabilities recorded through other expense, net in the statements of operations. Future Rights to Purchase Series C-2 Redeemable Convertible Preferred Stock The Company’s Series C Preferred Stock Purchase Agreement provides additional committed funding of up to $79,999 thousand, through the purchase of up to 27,137,000 shares of Series C-2 redeemable convertible preferred stock based on the completion of certain operational milestones at a predetermined price of $2.94797 per share, to certain Series C-1 Investors. This commitment is called the Series C-2 Redeemable Convertible Preferred Stock Issuance Right. The value of the Series C-2 Redeemable Convertible Preferred Stock Issuance Right is determined based on significant inputs not observable in the market, which represents a Level 3 measurement within the fair value hierarchy. The fair value of the Series C-2 Redeemable Convertible Preferred Stock Issuance Right was determined using a Black-Scholes Merton option-pricing model. The Company utilized key assumptions, such as the fair value of Series C-2 redeemable convertible preferred stock, the volatility of peer companies’ stock prices, the risk-free interest rate based on the U.S. treasury yield, and the expected term (based on the shorter of remaining term to a significant event or expiration date of the purchase right) The Company measures the fair value of the Series C-2 Redeemable Convertible Preferred Stock Issuance Right at each reporting date, with subsequent gains and losses from remeasurement of Level 3 financial liabilities recorded in the Statements of Operations and Other Comprehensive Income. 2018 Convertible Note Automatic Conversion Rights In 2018 the Company issued a convertible note payable with a face value of $6,518 thousand with detachable Series B redeemable preferred stock warrants, which contained automatic conversion features upon a change in control, bridge financing or qualified financing in excess of $10,000 thousand. The automatic conversion is called the 2018 Redeemable Note Automatic Conversion Rights. The value of the 2018 Redeemable Note Automatic Conversion Rights is determined based on significant inputs not observable in the market, which represents a Level 3 measurement within the fair value hierarchy. The value of the 2018 Redeemable Note Automatic Conversion Rights were determined using a discounted cash flow model, which takes into account the estimated value of Series C redeemable convertible stock, estimated time to conversion, probability of conversion and the risk-free interest rate based on the U.S. treasury yield. The Company measures the fair value of the 2018 Redeemable Note Automatic Conversion Rights at each reporting date, with subsequent gains and losses from remeasurement of Level 3 financial liabilities recorded through other expense, net in the Statements of Operations. The following table sets forth a summary of changes in the fair value of the Company’s level 3 liabilities at fair value on a recurring basis for the years ended December 31, 2020 and 2019 (in thousands): 2020 2019 Warrant liabilities: Beginning balance January 1 $ 1,989 $ 1,648 Change in fair value 1,296 341 Fair value of warrants issued 44 — Ending balance December 31 3,329 1,989 2018 Convertible Note Automatic Conversion Rights liability: Beginning balance January 1 — 9 Change in fair value — 19 Fair value of derivatives extinguished upon note conversion — (28 ) Ending balance December 31 — — Series C-2 Convertible Preferred Stock Issuance Right liability: Beginning balance January 1 11,379 — Change in fair value 11,532 — Fair value of derivatives issued — 11,379 Ending balance December 31 22,911 11,379 Total $ 26,240 $ 13,368
ACON S2 Acquisition Corp [Member]
Fair Value Measurements	Note 11—Fair Value Measurements The following table presents information about the Company’s assets that are measured at fair value on a recurring basis as of December 31, 2020 and indicates the fair value hierarchy of the valuation tech niques th Quoted Prices in Significant Other Significant Other Description (Level 1) (Level 2) (Level 3) Assets: Investments held in Trust Account $ 250,004,454 $ — $ — Liabilities: Derivative warrant liabilities – Public Warrants $ 13,625,000 $ — $ — Derivative warrant liabilities – Private Warrants $ — $ — $ 7,729,400 Transfers to/from Levels 1, 2, and 3 are recognized at the end of the reporting period. The estimated fair value of the Public Warrants transferred from a Level 3 measurement to a Level 1 fair value measurement in November 2020, when the Public Warrants were separately listed and traded. The fair value of the Public Warrants issued in connection with the Public Offering were initially measured at fair value using a Monte Carlo simulation model and the fair value of the Private Placement Warrants have been estimated using the Black-Scholes-Merton model at inception and each subsequent measurement date. The fair value of Public Warrants issued in connection with the Initial Public Offering have been measured based on the listed market price of such warrants, a Level 1 measurement, since November 2020. For the period ended December 31, 2020, the Company recognized a charge to the statement of operations resulting from an increase in the fair value of liabilities of approximately $2.0 million presented as change in fair value of derivative warrant liabilities on the accompanying statement of operations. The estimated fair value of the Private Placement Warrants, and the Public Warrants prior to being separately listed and traded, is determined using Level 3 inputs. Inherent in a Monte Carlo simulation and modified Black_Scholes_Merton models are assumptions related to expected stock-price volatility, expected life, risk-free interest rate, dividend yield and probability of a successful acquisition. The Company estimates the volatility of its ordinary shares warrants based on implied volatility from the Company’s traded warrants and from historical volatility of select peer company’s ordinary shares that matches the expected remaining life of the warrants. The risk-free interest rate is based on the U.S. Treasury zero-coupon The following table provides quantitative information regarding Level 3 fair value measurements inputs at their measurement dates: As of September 21, 2020 As of September 30, 2020 As of 31, 2020 Stock price $ 9.42 - $9.64 $ 9.42 - $9.64 $ 10.08 Volatility 10.00 % 10.00 % 10.00 % Expected life of the options to convert 6.0 6.0 5.9 Risk-free rate 0.37 % 0.37 % 0.48 % Dividend yield 0.0 % 0.0 % 0.0 % Probability of merger 100.0 % 100.0 % 100.0 % The change in the level 3 fair value of the derivative warrant liabilities for the period from July 22, 2020 (inception) through December 31, 2020 Public Warrants Private Warrants Total Derivative warrant liabilities at July 3, 2020 (inception) $ — $ — $ — Issuance of Warrants 12,500,000 7,000,000 19,500,000 Change in fair value of derivative warrant liabilities 1,125,000 729,400 1,854,400 Transfer of Public Warrants to level 1 (13,625,000 ) — (13,625,000 ) Derivative warrant liabilities at December 31, 2020 $ — $ 7,729,400 $ 7,729,400	Note 11- Fair Value Measurements The following table presents information about the Company’s assets and liabilities that are measured at fair value on a recurring basis as of September 30, 2021 and December 31, 2020 and indicates the fair value hierarchy of the valuation techniques that the Company utilized to determine such fair value. September 30, 2021 Quoted Prices in Active Markets Significant Other Observable Inputs Significant Other Unobservable Inputs Description (Level 1) (Level 2) (Level 3) Assets: Investments held in Trust Account $ 250,016,847 $ — $ — Liabilities: Warrant liabilities - Public warrants $ 10,333,330 $ — $ — Warrant liabilities - Private warrants $ — $ — $ 9,883,720 Working capital loan - Related party $ — $ — $ 361,751 December 31, 2020 Quoted Prices in Active Markets Significant Other Observable Inputs Significant Other Unobservable Inputs Description (Level 1) (Level 2) (Level 3) Assets: Investments held in Trust Account $ 250,004,454 $ — $ — Liabilities: Warrant liabilities - Public warrants $ 13,625,000 $ — $ — Warrant liabilities - Private warrants $ — $ — $ 7,729,400 Transfers to/from Levels 1, 2, and 3 are recognized at the beginning of the reporting period. There were no transfers from a Level 3 measurement to a Level 1 fair value measurement for the nine months ended September 30, 2021. Level 1 assets include investments in mutual funds invested in government securities. The Company uses inputs such as actual trade data, benchmark yields, quoted market prices from dealers or brokers, and other similar sources to determine the fair value of its investments. As of September 30, 2021, the Company had sold its investments in mutual funds and the cash was maintained in the operating bank account. The fair value of warrants issued in connection with the Initial Public Offering were initially measured at fair value using a Monte Carlo simulation model and have subsequently been measured based on the listed market price of such warrants, a Level 1 measurement, since March 2021. The fair value of the Private Placement warrants have been estimated using a modified Black-Scholes-Merton (“BSM”) model at inception and subsequently at each measurement date, considering certain vesting conditions imposed by the Sponsor Letter Agreement on the Private Placement Warrants held by the Sponsor and executive officers and directors of the Company. For the three months ended September 30, 2021, the Company recognized a charge to the statement of operations resulting from an increase in the fair value of liabilities of $2.2 million presented as change in fair value of derivative warrant liabilities on the accompanying unaudited condensed statement of operations. For the nine months ended September 30, 2021, the Company recognized income in the statement of operations resulting from a decrease in the fair value of liabilities of $1.1 million presented as change in fair value of derivative warrant liabilities on the accompanying unaudited condensed statement of operations. The estimated fair value of the Private Placement Warrants, and the Public Warrants prior to being separately listed and traded, is determined using Level 3 inputs. Inherent in a Monte Carlo simulation and modified BSM models are assumptions related to expected stock-price volatility, expected life, risk-free interest rate, dividend yield and probability of a successful acquisition. The Company estimates the volatility of its warrants based on implied volatility from the Company’s traded warrants and from historical volatility of select peer company’s ordinary shares that matches the expected remaining life of the warrants. The risk-free interest rate is based on the U.S. Treasury zero-coupon The following table provides quantitative information regarding Level 3 fair value measurements inputs at their measurement dates: As of September 30, As of December 31 Stock price $ 9.97 $ 10.08 Volatility 42.2 % 10.0 % Expected life of the options to convert 5.02 5.9 Risk-free rate 0.98 % 0.48 % Dividend yield — — The Sponsor Letter Agreement imposes certain vesting conditions on the Private Placement Warrants held by the Sponsor and executive officers and directors of the Company (the “Private Placement Warrant Holders”). These vesting conditions were considered in the estimated fair value of the Private Placement Warrants as of September 30, 2021. If the proposed business combination closes, the Private Placement Warrant Holders agreed to forfeit 583,333 Private Placement Warrants and agreed that up to another 583,333 Private Placement Warrants would be subject to potential forfeiture within 54 months of closing the proposed business combination if certain price targets for the combined company’s common stock, ranging from $12.50 to $15.00 per common share, are not met. The Company estimated the probability of the stock price reaching $12.50 and $15.00 over the life of the 54-month The change in the fair value of the Level 3 derivative warrant liabilities for the nine months ended September 30, 2021 is summarized as follows: Derivative warrant liabilities at December 31, 2020 $ 7,729,400 Change in fair value of derivative warrant liabilities 2,154,320 Derivative warrant liabilities at September 30, 2021 $ 9,883,720 The change in the fair value of the working capital loan – related party measured with Level 3 inputs for the nine months ended September 30, 2021 is summarized as follows: Fair value of working capital loan - related party at December 31, 2020 $ — Initial fair value of working capital loan - related party 361,751 Change in fair value of working capital loan - related party — Fair value of working capital loan - related party, September 30, 2020 $ 361,751

Income Taxes

Income Taxes	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income Taxes	9. INCOME TAXES The Company did not record a tax provision for the three and nine months ended September 30, 2021 and 2020, respectively, due to the losses and valuation allowance against substantially all of the Company’s net deferred tax assets. The Company provides for a valuation allowance when it is more likely than not that some portion of, or all of the Company’s deferred tax assets will not be realized. Due to the Company’s history of losses, the Company determined that it is not more likely than not to realize its deferred tax assets.	14. INCOME TAXES Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. The significant components of deferred tax assets and liabilities are as follows (in thousands): As of December 31, 2020 2019 Deferred Tax Assets: Net operating losses $ 11,566 $ 7,365 Tax credit carryforward 47 12 Other 837 513 Deferred tax assets 12,450 7,890 Valuation allowance (12,450 ) (7,890 ) Deferred tax assets, net of valuation allowance $ — $ — ASC Topic 740 requires that the tax benefit of net operating losses, temporary differences and credit carryforwards be recorded as an asset to the extent that management assesses that realization is “more likely than not.” Realization of the future tax benefits is dependent on the Company’s ability to generate sufficient taxable income within the carryforward period. Because of the Company’s history of operating losses, management believes that recognition of the deferred tax assets arising from the above-mentioned future tax benefits is currently not likely and, accordingly, has provided a valuation allowance for fiscal years 2020 and 2019. The valuation allowance increased by $4,560 thousand during the year ended December 31, 2020. As of December 31, 2020, the Company has federal and state net operating loss carryforwards (“NOL”) of $44,121 thousand and $44,121 thousand, respectively. Of the federal NOL carryforwards, $33,666 thousand do not expire. The remaining federal and state carryforwards will begin to expire in 2032 and 2027, respectively. The Company also has $94 thousand of federal research and development credits that will begin to expire in 2039. Under Sections 382 and 383 of the Internal Revenue Code (“IRC”) of 1986, as amended, the Company’s NOL and research and development credit carryforwards, and other deferred tax assets may be limited or lost if cumulative changes in ownership exceed 50% within any rolling three-year period. The Company has not completed the IRC Sections 382 and 383 analyses regarding the limitation of NOL and credit carryforwards. If a change in ownership was to occur, then the annual limitation may result in the expiration of NOL and credit carryforwards before utilization. If eliminated, the related assets would be removed from the deferred tax assets schedule with a corresponding reduction in the valuation allowance. The effective tax rate of the Company’s provision for income taxes differs from the federal statutory rate as follows: Years Ended December 31, 2020 2019 Tax computed at federal statutory rate 21.0 % 21.0 % State tax, net of federal tax benefit 3.0 4.4 Stock compensation (0.2 ) (0.2 ) Permanent differences (8.9 ) (2.3 ) 163(I) Interest — (0.9 ) R&D tax credits 0.1 0.1 Other — (0.1 ) Valuation allowance (15.0 ) (22.0 ) Income tax expense (benefit) 0.0 % 0.0 % The changes in the Company’s uncertain tax positions are summarized as follows (in thousands): Balance as of December 31, 2018 $ — Additions in 2019 12 Balance as of December 31, 2019 12 Additions in 2020 35 Balance as of December 31, 2020 $ 47 During the years ended December 31, 2020 and 2019, the Company recognized uncertain tax positions of $35 thousand and $12 thousand, respectively, related to a reduction of the research and development credit deferred tax asset. Unrecognized tax benefits may change during the next twelve months for items that arise in the ordinary course of business. The Company does not expect a material change to its unrecognized tax benefits over the next twelve months that would have an adverse effect on its operating results. The Company recognizes interest and penalties accrued on any unrecognized tax benefits as a component of income tax expense. The Company had no accrued interest or penalties related to uncertain tax positions as of December 31, 2019 and 2020. The Company files federal and certain state income tax returns, which provide varying statutes of limitations on assessments. However, because of NOL carryforwards, substantially all tax years since inception remain open to federal and state tax examination.

Defined Contribution Plan

Defined Contribution Plan	12 Months Ended
	Dec. 31, 2020
Retirement Benefits [Abstract]
Defined Contribution Plan	15. DEFINED CONTRIBUTION PLAN The Company has a 401(k) plan to provide defined contribution retirement benefits for all employees who have completed six months of service. Employees may elect to contribute a portion of their pretax compensation to the 401(k) plan, subject to annual limitations. The Company may make profit-sharing contributions at the discretion of the Board of Directors. Employee contributions are fully always vested. For the years ended December 31, 2020 and 2019, the Company contributed $173 thousand and $35 thousand, respectively.

Related Party Transactions

Related Party Transactions	5 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2020	Sep. 30, 2021	Dec. 31, 2020
Related Party Transaction [Line Items]
Related Party Transactions			16. RELATED PARTY TRANSACTIONS The Company defines related parties as directors, executive officers, nominees for director, stockholders that have significant influence over the Company, or are a greater than 5% beneficial owner of the Company’s capital and their affiliates or immediate family members. During the year ended December 31, 2020, the Company hired consultants through one of its Board members to review its technology. The Company paid $31 thousand to the consultants. In 2018 and 2019, the Company issued convertible notes payable to investors who are also Board members of the Company. During the year ended December 31, 2019, the Company incurred interest expense related to the convertible notes payable in the amount of $499 thousand. Accrued interest on convertible notes payable totaling $615 thousand was converted to equity in August 2019.
ACON S2 Acquisition Corp [Member]
Related Party Transaction [Line Items]
Related Party Transactions	Note 6—Related Party Transactions Founder Shares On July 27, 2020, our Sponsor paid an aggregate of $25,000 for certain expenses on behalf of the Company in exchange for issuance of 7,187,500 Class B ordinary shares (the “Founder Shares”). The holders of the Founder Shares agreed to forfeit up to an aggregate of 937,500 Founder Shares, on a pro rata basis, to the extent that the option to purchase additional units is not exercised in full by the underwriters, so that the Founder Shares will represent 20% of the Company’s issued and outstanding shares after the Initial Public Offering. The over-allotment option expired unexercised on October 31, 2020, thus the 937,500 of Class B ordinary shares were forfeited. The Initial Shareholders agreed not to transfer, assign or sell any of their Founder Shares until the earlier to occur of (A) one year after the completion of the initial Business Combination and (B) subsequent to the initial Business Combination, (x) if the closing price of Class A ordinary shares equals or exceeds $12.00 per share (as adjusted for share splits, share capitalizations, reorganizations, recapitalizations and the like) for any 20 trading days within any 30-trading day Related Party Loans On July 27, 2020, our Sponsor agreed to loan the Company up to $300,000 to be used for the payment of costs related to the Initial Public Offering pursuant to a promissory note (the “Note”). The Note was non-interest bearing, In addition, in order to finance transaction costs in connection with a Business Combination, our Sponsor, members of the Company’s founding team or any of their affiliates may, but are not obligated to, loan the Company funds as may be required (“Working Capital Loans”). If the Company completes a Business Combination, the Company would repay the Working Capital Loans out of the proceeds of the Trust Account released to the Company. Otherwise, the Working Capital Loans would be repaid only out of funds held outside the Trust Account. In the event that a Business Combination does not close, the Company may use a portion of proceeds held outside the Trust Account to repay the Working Capital Loans but no proceeds held in the Trust Account would be used to repay the Working Capital Loans. The Working Capital Loans would either be repaid upon consummation of a Business Combination, without interest, or, at the lender’s discretion, up to $1,500,000 of such Working Capital Loans may be convertible into warrants of the post Business Combination entity at a price of $1.50 per warrant. The warrants would be identical to the Private Placement Warrants. Except for the foregoing, the terms of such Working Capital Loans, if any, have not been determined and no written agreements exist with respect to such loans. To date, the Company had no borrowings under the Working Capital Loans. Administrative Services Agreement The Company entered into an agreement providing that, commencing on September 16, 2020 through the earlier of consummation of the initial Business Combination and the liquidation, the Company will pay our Sponsor $10,000 per month for office space, secretarial and administrative services provided to the Company. In addition, our Sponsor, executive officers and directors, and any of their respective affiliates will be reimbursed for any out-of-pocket expenses	Note 6 - Related Party Transactions Founder Shares On July 27, 2020, our Sponsor paid an aggregate of $25,000 for certain expenses on behalf of the Company in exchange for issuance of 7,187,500 Class B ordinary shares (the “Founder Shares”). The holders of the Founder Shares agreed to forfeit up to an aggregate of 937,500 Founder Shares, on a pro rata basis, to the extent that the option to purchase additional units is not exercised in full by the underwriters, so that the Founder Shares will represent 20% of the Company’s issued and outstanding shares after the Initial Public Offering. The over-allotment option expired unexercised on October 31, 2020, thus the 937,500 of Class B ordinary shares were forfeited. The Initial Shareholders agreed not to transfer, assign or sell any of their Founder Shares until the earlier to occur of (A) one year after the completion of the initial business combination and (B) subsequent to the initial business combination, (x) if the closing price of Class A ordinary shares equals or exceeds $12.00 per share (as adjusted for share splits, share capitalizations, reorganizations, recapitalizations and the like) for any 20 trading days within any 30-trading Related Party Loans On July 27, 2020, the company entered into the Note. The Note was non-interest In addition, in order to finance transaction costs in connection with a business combination, our Sponsor, members of the Company’s founding team or any of their affiliates may, but are not obligated to, loan the Company funds as may be required (“Working Capital Loans”). If the Company completes a business combination, the Company would repay the Working Capital Loans out of the proceeds of the Trust Account released to the Company. Otherwise, the Working Capital Loans would be repaid only out of funds held outside the Trust Account. In the event that a business combination does not close, the Company may use a portion of proceeds held outside the Trust Account to repay the Working Capital Loans but no proceeds held in the Trust Account would be used to repay the Working Capital Loans. The Working Capital Loans would either be repaid upon consummation of a business combination, without interest, or, at the lender’s discretion, up to $1,500,000 of such Working Capital Loans may be convertible into warrants of the post business combination entity at a price of $1.50 per warrant. The warrants would be identical to the Private Placement Warrants. Except for the foregoing, the terms of such Working Capital Loans, if any, have not been determined and no written agreements exist with respect to such loans. As of September 30, 2021, the Company had borrowed approximately $362,000 under the Working Capital Loans. Administrative Services Agreement The Company entered into an agreement providing that, commencing on September 16, 2020 through the earlier of consummation of the initial business combination or the liquidation, the Company will pay our Sponsor $10,000 per month for office space, secretarial and administrative services provided to the Company. In addition, our Sponsor, executive officers and directors, and any of their respective affiliates will be reimbursed for any out-of-pocket

Subsequent Events

Subsequent Events	5 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2020	Sep. 30, 2021	Dec. 31, 2020
Subsequent Events		10. SUBSEQUENT EVENTS The Company has evaluated subsequent events through November 22, 2021, the date the condensed financial statements were available to be issued. On October 8, 2021, the Company completed the Merger and received approximately $246,000 thousand in net proceeds. Upon the Merger closing, each share of the Company’s common stock, par value $0.0001 per share (“ESS Common Stock”) was converted into the right to receive shares of New ESS common stock at an exchange ratio of approximately 1.47 (the “Per Share Consideration”) as calculated pursuant to the Merger Agreement. The aggregate consideration paid to ESS stockholders in connection with the Merger (excluding any potential Earnout Stock), was 99,562,793 shares of New ESS Common Stock. The Merger occurred based on the following events contemplated by the Merger Agreement: • Each issued and outstanding share of the Company’s preferred stock was converted into shares of ESS Common Stock at the then-effective conversion rate as calculated pursuant to the Company’s Certificate of Incorporation immediately prior to the closing; • Each issued and outstanding warrant of the Company was exercised in full in exchange for the issuance of shares of ESS Common Stock immediately prior to the closing; • Each issued and outstanding share of ESS Common Stock (including shares of ESS Common Stock resulting from the conversion of preferred stock and the exercise and settlement of all outstanding warrants) was cancelled and converted into the right to receive a number of shares of New ESS Common Stock equal to the Per Share Consideration; • Each issued and outstanding vested and unvested Company option was converted into options of New ESS exercisable for shares of New ESS Common Stock with the same terms except for the number of shares exercisable and the exercise price, each of which was adjusted using the Per Share Consideration; and • Each issued and outstanding vested and unvested restricted stock unit (“RSU”) of the Company was converted into New ESS RSUs for the same number of shares of New ESS Common Stock with the same terms. Other events that took place in connection with the Merger are summarized below: • The issuance and sale of 25,000,000 shares of New ESS Common Stock at a purchase price of $10.00 per share for an aggregate purchase price of $250,000 thousand pursuant to the PIPE; • The issuance to ESS employees and other service providers of 824,998 RSUs (the “Incentive RSU Pool”), which vest subject to meeting certain future earnout milestone events and continued service; • Pursuant to the Merger Agreement, up to 54 months after October 8, 2021, New ESS may issue to eligible ESS securityholders, on a pro rata basis, up to 16,500,000 shares of additional New ESS Common Stock less any ESS RSUs issued pursuant to the Incentive RSU Pool, issuable in two equal tranches upon the occurrence of the respective Earnout Milestone Events; and • Repayment of $20,000 thousand in principal plus accrued interest to settle amounts outstanding under the Company’s Bridge Loan, following the Closing.	17. SUBSEQUENT EVENTS The Company has evaluated subsequent events through June 16, 2021, the date the financial statements were available to be issued. New Lease Facility The Company entered into a new building lease, which commenced on January 1, 2021, has an initial five-year term plus an option to extend for an additional five years. Following an initial rent abatement period, monthly base rent of $42 thousand per month, plus expenses, begins July 1, 2021. Base rent increases 3% annually beginning on July 1, 2022. Fourth Restatement of Certificate of Incorporation On February 26, 2021, the Company amended and restated its certificate of incorporation (the “Fourth Restatement”). This Fourth Amended and Restated Certificate of Incorporation replaces all previous Certificates of Incorporation. See note 10 for details of previous Certificates of Incorporation. Under the Fourth Restatement, the Company is authorized to issue 79,000,000 shares of common stock with $0.0001 par value. The Fourth Restatement increased the number of shares of redeemable convertible preferred stock authorized for issuance from 61,436,037 to 62,072,064 with $0.0001 par value, of which 5,941,109 shares are designated as Series A, 12,011,923 shares are designated as Series B, 16,345,688 shares are designated as Series C-1, and the remaining 27,773,344 shares are designated as Series C-2. Under the Fourth Restatement, dividends, original issue price and liquidation preference remain the same as the Third Restatement. Sale of Series C-2 Redeemable Convertible Preferred Stock In March 2021, the Company issued 3,900,988 shares of Series C-2 redeemable convertible preferred stock for $2.94797 per share, totaling $11,500 thousand. In connection with the sale of the Series C-2 redeemable convertible preferred stock, the Company issued warrants to purchase 585,145 shares of Series C-2 redeemable convertible preferred stock. The warrants are exercisable at a price of $0.0001 per share. The purchases of Series C-2 redeemable convertible preferred stock replaced the Series C-2 Redeemable Convertible Purchase Right to 23,236,327 shares. Merger with ACON S2 Acquisition Corp. On May 6, 2021, the Company entered into a definitive business combination agreement with ACON, a special purpose acquisition company (“SPAC”). The merger is valued at $1.07 billion and is projected to provide $465,000 thousand net cash. The transaction is expected to close in the latter half of 2021. Amendment to Series C-2 Redeemable Convertible Preferred Stock Purchase Right On May 7, 2021, the Company amended its Series C-2 Preferred Stock Purchase Agreement And Amendment To Series C Preferred Stock Purchase Agreement. Under the terms of the amended agreement, in conjunction with a successful SPAC merger with ACON, two existing investors will purchase 5,427,464 additional shares of Series C-2 redeemable convertible preferred stock and will receive warrants to purchase 14,364,207 shares of Series C-2 redeemable convertible preferred stock with an exercise price of $ .0001
ACON S2 Acquisition Corp [Member]
Subsequent Events	Note 12—Subsequent Events Management has evaluated subsequent events or transactions that occurred up to the date the financial statements were issued. Based on this review, Management determined that all events or transactions that require potential adjustment to or disclosure in the financial statements have been recognized or disclosed herein.	Note 12-Subsequent Management has evaluated subsequent events and transactions that occurred after the balance sheet date through the date the financial statements were available for issuance. Based upon this review, except as noted above regarding the consummation of the business combination on October 8, 2021 (see Note 1 for additional information), the Company did not identify any subsequent events that would have required adjustment or disclosure in the financial statements.

Description of Business and S_2

Description of Business and Summary of Significant Accounting Policies (Policies)	5 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2020	Sep. 30, 2021	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business		Description of Business ESS Tech, Inc. (the “Company”) was founded as Energy Storage Systems, LLC in Portland, Oregon in 2011. The Company converted to a Delaware corporation and changed its name to ESS Tech, Inc. in 2014. The Company does not have any subsidiaries. The Company develops long-duration iron flow batteries for commercial and utility-scale energy storage applications requiring four or more hours of flexible energy capacity. The Company’s products are designed for a 25-year The Company is in the research and development phase. Its product is still being developed and does not yet meet standard specifications to be sold (“Commercially Available”). On October 8, 2021 (the “Closing Date”), ESS Tech, Inc., a Delaware corporation (“New ESS”), formerly known as ACON S2 Acquisition Corp., a Delaware corporation (“STWO”), consummated the previously announced merger pursuant to that certain Agreement and Plan of Merger, dated May 6, 2021 (the “Merger Agreement”), by and among STWO, SCharge Merger Sub, Inc., a Delaware corporation and wholly owned direct subsidiary of STWO (“Merger Sub”), and the Company following the approval at a special meeting of the stockholders of STWO held on October 5, 2021. Pursuant to the terms of the Merger Agreement, STWO deregistered by way of continuation under the Cayman Islands Companies Act (2021 Revision) and registered as a corporation in the State of Delaware under Part XII of the Delaware General Corporation Law, and a business combination between STWO and the Company was effected through the merger of Merger Sub with and into the Company, with the Company surviving as a wholly owned subsidiary of STWO (together with the other transactions described in the Merger Agreement, the “Merger”). On the Closing Date, STWO changed its name from “ACON S2 Acquisition Corp” to “ESS Tech, Inc.”, and its shares and warrants commenced trading on the New York Stock Exchange under the new ticker symbols “GWH” and “GWH.W”, respectively. As a result of its initial public offering of Class A ordinary shares in September 2020, STWO held approximately $250,000 thousand in a trust account (the “Trust Account”). In connection with the Merger, STWO stockholders holding 20,754,719 shares of STWO’s Class A ordinary shares exercised their right to redeem such shares. As a result, approximately $207,500 thousand of funds were withdrawn from the Trust Account to fund participant share redemptions. Also, in connection with the Merger, on the Closing Date, STWO issued and sold an aggregate of 25,000,000 shares of STWO Class A ordinary shares for a purchase price of $10.00 per share and an aggregate purchase price of $250,000 thousand pursuant to subscription agreements, dated as of May 6, 2021, with certain accredited investors, in a private investment in public equity offering (“PIPE”). Cash received by the Company from the consummation of the Merger including the PIPE and the remaining balance in the STWO Trust Account after estimated expenses approximated $246,000 thousand.	Description of Business— The Company develops long-duration iron flow batteries for commercial and utility-scale energy storage applications requiring four or more hours of flexible energy capacity. The Company’s products are designed for a 25-year operating life without performance degradation, with minimal annual operations and maintenance requirements. The Company is in the research and development phase. Its product is still being developed and has not met standard specifications to be sold (“Commercially Available”).
Basis of Presentation		Basis of presentation The accompanying unaudited condensed financial statements have been prepared in accordance with generally accepted accounting principles in the United States (“U.S. GAAP”). Certain information and note disclosures normally included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted. Accordingly, these unaudited condensed financial statements should be read in conjunction with the audited financial statements and accompanying notes for the year ended December 31, 2020. The condensed balance sheet as of December 31, 2020, included herein was derived from the audited financial statements of the Company as of that date. The unaudited condensed financial statements, in the opinion of management, reflect all adjustments necessary to present fairly the Company’s financial position as of September 30, 2021, and the Company’s results of operations and comprehensive loss, redeemable convertible preferred stock and stockholders’ deficit activities for the three and nine months ended September 30, 2021, and 2020, and the cash flows for the nine months ended September 30, 2021, and 2020. The results for the three and nine months ended September 30, 2021 are not necessarily indicative of the results to be expected for the year ending December 31, 2021, any interim period or for any other future year.	Basis of Presentation
Emerging Growth Company		Emerging Growth Company Section 102(b)(1) of the Jumpstart Our Business Startups Act of 2012 (the “JOBS Act”) exempts emerging growth companies from being required to comply with new or revised financial accounting standards until private companies (that is, those that have not had a Securities Act registration statement declared effective or do not have a class of securities registered under the Securities Exchange Act of 1934, as amended) are required to comply with the new or revised financial accounting standards. The JOBS Act provides that an emerging growth company can elect to opt out of the extended transition period and comply with the requirements that apply to non-emerging This may make comparison of the Company’s financial statements with another public company that is neither an emerging growth company nor an emerging growth company that has opted out of using the extended transition period difficult or impossible because of the potential differences in accounting standards used.	Emerging Growth Company Section 102(b)(1) of the Jumpstart Our Business Startups Act of 2012 (the “JOBS Act”) exempts emerging growth companies from being required to comply with new or revised financial accounting standards until private companies (that is, those that have not had a Securities Act registration statement declared effective or do not have a class of securities registered under the Securities Exchange Act of 1934, as amended) are required to comply with the new or revised financial accounting standards. The JOBS Act provides that an emerging growth company can elect to opt out of the extended transition period and comply with the requirements that apply to non-emerging growth companies but any such election to opt out is irrevocable. The Company is keeping its election to be able to defer the adoption of a new or revised standard at the time private companies are required to adopt the new or revised standard. This may make comparison of the Company’s financial statement with another public company that is neither an emerging growth company nor an emerging growth company that has opted out of using the extended transition period difficult or impossible because of the potential differences in accounting standards used.
Liquidity and Going concern		Liquidity and Going concern In connection with preparing financial statements for each interim and annual reporting period, the Company evaluates whether there are conditions or events, considered in the aggregate, that raise substantial doubt about its ability to continue as a going concern within one year after the date on which the financial statements are issued in accordance with FASB Accounting Standards Update No. 2014-15, Presentation of Financial Statements—Going Concern (Subtopic 205-40): 2014-15”) The Company’s financial statements have been prepared assuming that it will continue as a going concern , As of September 30, 2021, the Company had approximately $8,019 thousand in cash and cash equivalents. As also reflected in the condensed financial statements, the Company had an accumulated deficit on September 30, 2021, and December 31, 2020, and had net losses and net cash used in operating activities for the reporting periods then ended. These factors, coupled with the available cash on hand as of September 30, 2021, and compared to management’s operating plan, raised substantial doubt about the Company’s ability to continue as a going concern. However, as discussed in Note 10 Subsequent Events, the Company effected the close of the Merger with STWO on October 8, 2021, which contributed approximately $246,000 thousand, from the transaction. The Company has capitalized $3,471 thousand of transaction costs as of September 30, 2021. The Company believes that the net proceeds from the Merger plus its cash and cash equivalent balance at September 30, 2021 provide it with sufficient resources to continue as a going concern for at least the next 12 months from the date the condensed financial statements are issued.	Liquidity and Going concern In connection with preparing financial statements for each annual reporting period, the Company evaluates whether there are conditions or events, considered in the aggregate, that raise substantial doubt about its ability to continue as a going concern within one year after the date on which the financial statements are issued in accordance with FASB Accounting Standards Update No. 2014-15, Presentation of Financial Statements—Going Concern (Subtopic 205-40): Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern (“ASU 2014-15”) The Company’s financial statements have been prepared assuming that it will continue as a going concern , As of December 31, 2020, the Company had $4,901 thousand of cash and cash equivalents. As reflected also in the financial statements, the Company had an accumulated deficit on December 31, 2020, and has had recurring net losses and net cash used in operating activities for the reporting period then ended. These factors coupled with the available cash on hand compared to management’s operating plan raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date the financial statements are issued. The financial statements do not include any adjustments to reflect the possible future effects on the recoverability and classification of assets or the amounts and classification of liabilities that may result in the Company not being able to continue as a going concern, other than the reclassification of notes payable, non-current and the related debt issuance costs to current liabilities. The principal payments and accrued interest due under the notes payable agreements have been classified as current liabilities as of December 31, 2020 due to the considerations discussed above and the assessment that the material adverse change clause under the notes payable agreements is not within the Company’s control. The Company has not been notified of an event of default by the Lenders as of the date of issuance of these financial statements. The Company’s plan is to seek additional funding through the completion of a business combination with ACON S2 Acquisition Corp. (“ACON”) (see Note 17). At this time, the Company is focused on completing the business combination with ACON, which is subject to the approval of the shareholders of both companies, regulatory approval from the Securities and Exchange Commission and other customary closing conditions, and is limited in its efforts to raise additional capital from secondary sources. If the Company is unable to complete the business combination with ACON, then the Company would have to pursue a secondary course of action to seek additional capital through other debt and equity financings. If the Company is unable to raise sufficient additional capital, through future debt or equity financings or through strategic and collaborative ventures with third parties, then the Company will not have sufficient cash flows and liquidity to fund its planned business operations for the year following the date the audited financial statements were available to be issued, as of June 16, 2021. There can be no assurances that the Company will be able to complete the business combination, or that in the event that the business combination does not take place, the Company will be able to secure alternate forms of financing at terms that are acceptable to management, if at all. If the Company is unable to raise additional capital when required or on acceptable terms, or unable to continue as a going concern, then the Company may be required to scale back or discontinue the development of its product, reduce headcount, file for bankruptcy, reorganize, merge with another entity, cease operations, and/or stockholders may lose all or part of their investment in the Company’s stock.
Risks and Uncertainties		Significant Risks and Uncertainties The Company is subject to those risks common in the technology industry and also those risks common to early-stage companies including, but not limited to, the possibility of not being able to successfully develop or market its products, technological obsolescence, competition, dependence on key personnel and key external alliances, the successful protection of its proprietary technologies, compliance with government regulations, and the possibility of not being able to obtain additional financing when needed. COVID-19	Risks and Uncertainties In March 2020, the World Health Organization declared the outbreak of a novel corona virus as a pandemic. The pandemic has reached every region of the world and has resulted in widespread adverse impacts on the global economy. In response, the Company has modified certain business and workforce practices (including discontinuing all non-essential business travel, implementing a temporary work-from-home policy for employees who can execute their work remotely and encouraging employees to adhere to local and regional social distancing, more stringent hygiene and cleaning protocols across the Company’s facilities and operations and self-quarantining recommendations) to conform to government restrictions and best practices encouraged by governmental and regulatory authorities. However, the quarantine of personnel or the inability to access the Company’s facilities or customer sites could adversely affect the Company’s operations. As of the date of this report, the Company’s efforts to respond to the challenges presented by the conditions described above have allowed the Company to minimize the impacts to its business.
Segment information		Segment information The Company has determined that its Chief Executive Officer (“CEO”) is its chief operating decision maker (“CODM”). The CEO reviews financial information presented for purposes of assessing performance and making decisions on how to allocate resources. The Company has determined that it operates in a single reportable segment. All the Company’s operations and long-lived assets were attributable to operations in the United States as of September 30, 2021 and December 31, 2020.	Segment information single All the Company’s operations and long-lived assets were attributable to operations in the United States as of December 31, 2020 and 2019.
Use of Estimates		Use of Estimates The preparation of the financial statements in conformity with U.S. GAAP requires management to make estimates, judgments and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent liabilities as of the date of the financial statements and the reported amounts of expenses during the reporting periods. Such estimates relate to, among others, the useful lives and assessment of recoverability of property and equipment, deferred tax assets valuation, determination of the fair value of the Company’s Bridge Loan, common and preferred stock, warrant liabilities, Series C-2	Use of Estimates
Concentration of Supply Chain Risk		Concentration of Supply Chain Risk The Company uses various raw materials and components that are critical to the future manufacturing of its energy storage solutions. Suppliers must undergo a qualification process, which typically requires four to twelve months to complete. The Company does not know whether it will be able to maintain long-term supply relationships with its critical suppliers, or secure new long-term supply relationships on terms that will allow it to achieve its objectives, if at all. A supplier’s failure to develop and supply components in a timely manner or to supply components that meet the Company’s quality, quantity, cost requirements or technical specifications, or the Company’s inability to source these components from alternative providers on a timely basis or on terms acceptable to the Company could each harm the Company’s ability to manufacture its energy storage solutions at the time when its products are commercially ready. In addition, to the extent the processes that the Company’s suppliers use to manufacture components are proprietary, the Company may be unable to obtain comparable components from alternative suppliers, all of which could harm the Company’s business prospects, results of operations and financial condition.	Concentration of Supply Chain Risk
Concentration of Credit Risk		Concentration of Credit Risk Financial instruments that potentially subject the Company to concentration of credit risk consist of cash and cash equivalents and restricted cash. The Company’s cash and cash equivalents include cash in bank accounts and a money market account. The Company’s restricted cash includes a certificate of deposit and performance and payment bond. Deposits held with banks may exceed the amount of insurance provided on such deposits.	Concentration of Credit Risk
Net loss per share			Net loss per share
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all short-term investments with an original maturity of three months or less when purchased to be cash equivalents. As of December 31, 2020, the Company did not have any cash equivalents.		Cash and Cash Equivalents
Restricted Cash			Restricted Cash
Grants Receivable			Grants Receivable The portion of such funding that the Company may be required to repay in certain circumstances is recorded in accrued and other liabilities and was $186 thousand and $0 for the years ended December 31, 2020 and 2019, respectively. The portion of such funding that the Company is not required to repay is recorded as a reduction of research and development costs and was $40 thousand and $20 thousand for the years ended December 31, 2020 and 2019, respectively. Grants receivable balance was $0 as of December 31, 2020 and 2019.
Property and Equipment			Property and Equipment three The Company evaluates the recoverability of property and equipment for possible impairment whenever events or circumstances indicate that the carrying amount of such assets may not be recoverable. The Company assesses the alternative use of an asset, the condition of the asset and the current market demand to determine if an asset is impaired. No impairment was recognized during the years ended December 31, 2020 and 2019.
Debt Issuance Costs			Debt Issuance Costs
Revenue Recognition			Revenue Recognition Revenue from Contracts with Customers (Topic 606)
Sales and Marketing			Sales and Marketing
Research and Development			Research and Development
General and Administrative			General and Administrative
Stock-Based Compensation			Stock-Based Compensation Compensation – Stock Compensation (“ASC 718”) The Company measures compensation expense for all stock-based payment awards for stock options granted to employees and non-employees based on the estimated fair values on the date of the grant. The fair value of each stock option granted is estimated using the Black-Scholes Merton option-pricing model using the single-option award approach. The following assumptions are used in the Black-Scholes Merton option-pricing model: Risk-Free Interest Rate Expected Volatility Expected Term Dividend Yield In accordance with ASU 2016-09, the Company may account for forfeitures as they occur or use estimated forfeitures. The Company elected to use actual forfeitures. The share-based compensation expense is recognized using a straight-line basis over the requisite service periods of the awards. The requisite service period is generally the vesting period of such options, and the stock-based compensation expense is presented as a component of operating expenses within the statements of operations. The Company recognizes all excess tax benefits and deficiencies for share-based awards as an income tax expense or benefit in the statements of operations. Excess tax benefits are classified with other income tax in the cash flows as an operating activity. The Company accounts for stock-based compensation for nonemployees in accordance with ASC 505 “ Equity Based Payments to Nonemployees” (“ASC 505”)
Income Taxes			Income Taxes ASC 740, Accounting for Income Taxes, The Company recognizes accrued interest and penalties related to unrecognized tax benefits as income tax expense. No amounts were accrued for the payment of interest and penalties as of December 31, 2020 and 2019 as the Company is currently not aware of any issues under review that could result in significant payments, accruals, or material deviation from its position.
Fair Value			Fair Value Fair Value Measurements ASC 820 establishes a hierarchy for inputs used in measuring fair value that maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that observable inputs be used when available. Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company’s assumptions about what market participants would use in pricing the asset or liability based on the best information available in the circumstances. The hierarchy is broken down into three levels based on the reliability of inputs as follows: Level 1: Level 2: Level 3: Because of the uncertainties inherent in the valuation of assets or liabilities for which there are no observable inputs, those estimated fair values may differ significantly from the values that may have been used had a ready market for the assets or liabilities existed.
Recently Issued Accounting Standards			Recently Issued Accounting Standards In February 2016, the Financial Accounting Standards Board (“FASB”) issued No. ASU 2016-02, Lease s (Topic 842) , Leases (Topic 842) In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes In August 2020, the FASB issued ASU 2020-06 , Debt with Conversion and Other Options (Subtopic 470-20) Contracts in Entity’s Own Equity (Subtopic 815-40) Derivatives and Hedging Derivatives and Hedging—Contracts in Entity’s Own Equity
Significant Accounting Policies		Significant Accounting Policies There have been no material changes in the significant accounting policies described in our Audited Financial Statements as of and for the year ended December 31, 2020.
Accounting Standards Pending Adoption		Accounting Standards Pending Adoption There have been no material changes in the accounting standards pending adoption described in the Company’s audited financial statements for the year ended December 31, 2020.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	5 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2020	Sep. 30, 2021	Dec. 31, 2020
Use of Estimates		Use of Estimates The preparation of the financial statements in conformity with U.S. GAAP requires management to make estimates, judgments and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent liabilities as of the date of the financial statements and the reported amounts of expenses during the reporting periods. Such estimates relate to, among others, the useful lives and assessment of recoverability of property and equipment, deferred tax assets valuation, determination of the fair value of the Company’s Bridge Loan, common and preferred stock, warrant liabilities, Series C-2	Use of Estimates
Concentration of Credit Risk		Concentration of Credit Risk Financial instruments that potentially subject the Company to concentration of credit risk consist of cash and cash equivalents and restricted cash. The Company’s cash and cash equivalents include cash in bank accounts and a money market account. The Company’s restricted cash includes a certificate of deposit and performance and payment bond. Deposits held with banks may exceed the amount of insurance provided on such deposits.	Concentration of Credit Risk
Fair Value Measurements			Fair Value Fair Value Measurements ASC 820 establishes a hierarchy for inputs used in measuring fair value that maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that observable inputs be used when available. Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company’s assumptions about what market participants would use in pricing the asset or liability based on the best information available in the circumstances. The hierarchy is broken down into three levels based on the reliability of inputs as follows: Level 1: Level 2: Level 3: Because of the uncertainties inherent in the valuation of assets or liabilities for which there are no observable inputs, those estimated fair values may differ significantly from the values that may have been used had a ready market for the assets or liabilities existed.
Income Taxes			Income Taxes ASC 740, Accounting for Income Taxes, The Company recognizes accrued interest and penalties related to unrecognized tax benefits as income tax expense. No amounts were accrued for the payment of interest and penalties as of December 31, 2020 and 2019 as the Company is currently not aware of any issues under review that could result in significant payments, accruals, or material deviation from its position.
Net Loss Per Ordinary Share			Net loss per share
Recent Accounting Standards			Recently Issued Accounting Standards In February 2016, the Financial Accounting Standards Board (“FASB”) issued No. ASU 2016-02, Lease s (Topic 842) , Leases (Topic 842) In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes In August 2020, the FASB issued ASU 2020-06 , Debt with Conversion and Other Options (Subtopic 470-20) Contracts in Entity’s Own Equity (Subtopic 815-40) Derivatives and Hedging Derivatives and Hedging—Contracts in Entity’s Own Equity
ACON S2 Acquisition Corp [Member]
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires t he	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires the Company’s management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, including, but not limited to, accrued expenses and derivative warrant liabilities. Making estimates requires management to exercise significant judgment. It is at least reasonably possible that the estimate of the effect of a condition, situation or set of circumstances that existed at the date of the financial statements, which management considered in formulating its estimate, could change in the near term due to one or more future confirming events. Accordingly, the actual results could differ significantly from those estimates.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all short-term investments with an original maturity of three months or less when purchased to be cash equivalents. As of December 31, 2020, the Company did not have any cash equivalents.	Cash and Cash Equivalents The Company considers all short-term investments with an original maturity of three months or less when purchased to be cash equivalents. As of September 30, 2021, the Company did not have any cash equivalents.
Investments Held in Trust Account	Investments Held in Trust Account Upon the closing of the Initial Public Offering and the Private Placement, $250.0 million of the net proceeds of the sale of the Units in the Initial Public Offering and the Private Placement were placed in the Trust Account and invested in money market funds meeting certain conditions under Rule 2a-7 promulgated using	Investments Held in the Trust Account The Company’s portfolio of investments is comprised of U.S. government securities, within the meaning set forth in Section 2(a)(16) of the Investment Company Act, with a maturity of 185 days or less, or investments in money market funds that invest in U.S. government securities and generally have a readily determinable fair value, or a combination thereof. When the Company’s investments held in the Trust Account are comprised of U.S. government securities, the investments are classified as trading securities. When the Company’s investments held in the Trust Account are comprised of money market funds, the investments are recognized at fair value. Trading securities and investments in money market funds are presented on the condensed balance sheets at fair value at the end of each reporting period. Gains and losses resulting from the change in fair value of these securities is included in unrealized gain on investments held in Trust Account in the accompanying unaudited condensed consolidated statements of operations. The estimated fair values of investments held in the Trust Account are determined using available market information.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that potentially subject the Company to concentrations of credit risk consist of cash accounts in a financial institution, which, at times, may exceed the Federal Depository Insurance Coverage of $250,000, and investments held in Trust Account. At December 31, 2020, the Company has not experienced losses on these accounts.	Concentration of Credit Risk Financial instruments that potentially subject the Company to concentrations of credit risk consist of cash accounts in a financial institution, which, at times, may exceed the Federal Depository Insurance Coverage of $250,000, and investments held in Trust Account. At September 30, 2021 and December 31, 2020, the Company has not experienced losses on these accounts.
Fair Value of Financial Instruments	Fair Value of Financial Instruments Fair value is defined as the price that would be received for sale of an asset or paid for transfer of a liability, in an orderly transaction between market participants at the measurement date. GAAP establishes a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). These tiers include: • Level 1, defined as observable inputs such as quoted prices for identical instruments in active markets; • Level 2, defined as inputs other than quoted prices in active markets that are either directly or indirectly observable such as quoted prices for similar instruments in active markets or quoted prices for identical or similar instruments in markets that are not active; and • Level 3, defined as unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions, such as valuations derived from valuation techniques in which one or more significant inputs or significant value drivers are unobservable. In some circumstances, the inputs used to measure fair value might be categorized within different levels of the fair value hierarchy. In those instances, the fair value measurement is categorized in its entirety in the fair value hierarchy based on the lowest level input that is significant to the fair value measurement. As of December 31, 2020, the carrying values of cash approximate their fair values due to the short-term nature of the instruments. As of December 31, 2020, the Company’s portfolio of investments held in the Trust Account is comprised entirely of investments in money market funds that invest in U.S. government securities.	Fair Value of Financial Instruments The fair value of the Company’s assets and liabilities, which qualify as financial instruments under the FASB ASC Topic 820, “Fair Value Measurements,” approximates the carrying amounts represented in the condensed balance sheets.
Fair Value Measurements		Fair Value Measurements The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). These tiers include: • Level 1, defined as observable inputs such as quoted prices for identical instruments in active markets; • Level 2, defined as inputs other than quoted prices in active markets that are either directly or indirectly observable such as quoted prices for similar instruments in active markets or quoted prices for identical or similar instruments in markets that are not active; and • Level 3, defined as unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions, such as valuations derived from valuation techniques in which one or more significant inputs or significant value drivers are unobservable. In some circumstances, the inputs used to measure fair value might be categorized within different levels of the fair value hierarchy. In those instances, the fair value measurement is categorized in its entirety in the fair value hierarchy based on the lowest level input that is significant to the fair value measurement. As of September 30, 2021 and December 31, 2020, the carrying values of cash, prepaid expenses, accounts payable and accrued expenses approximate their fair values due to the short-term nature of the instruments. The Company’s investments held in Trust Account are comprised of investments in U.S. Treasury securities with an original maturity of 185 days or less or investments in a money market funds that comprise only U.S. treasury securities and are recognized at fair value. The fair value of investments held in Trust Account is determined using quoted prices in active markets.
Working Capital Loan – Related Party		Working Capital Loan – Related Party The Company has elected the fair value option to account for its working capital loan – related party with its Sponsor as defined and more fully described in Note 5. As a result of applying the fair value option, the Company records each draw at fair value with a gain or loss recognized at issuance, and subsequent changes in fair value are recorded as change in the fair value of working capital loan – related party on the condensed statement of operations. The fair value is based on prices or valuation techniques that require inputs that are both unobservable and significant to the overall fair value measurement. These inputs reflect management’s and, if applicable, an independent third-party valuation firm’s own assumption about the assumptions a market participant would use in pricing the asset or liability.
Derivative Warrant Liabilities	Derivative Warrant Liabilities The Company does not use derivative instruments to hedge exposures to cash flow, market, or foreign currency risks. The Company evaluates all of its financial instruments, including issued stock purchase warrants, to determine if such instruments are derivatives or contain features that qualify as embedded derivatives, pursuant to ASC 480 and ASC 815-15. re-assessed The Company issued an aggregate of 8,333,333 ordinary shares warrants associated with Units issued to investors in our Initial Public Offering and the underwriters’ exercise of their overallotment option and we issued 4,666,667 Private Placement Warrants. All of our outstanding warrants are recognized as derivative liabilities in accordance with ASC 815-40.	Derivative warrant liabilities The Company does not use derivative instruments to hedge exposures to cash flow, market, or foreign currency risks. The Company evaluates all of its financial instruments, including issued share purchase warrants, to determine if such instruments are derivatives or contain features that qualify as embedded derivatives, pursuant to ASC 480 and FASB ASC Topic 815, “Derivatives and Hedging” (“ASC 815”). The classification of derivative instruments, including whether such instruments should be recorded as liabilities or as equity, is re-assessed The warrants issued in the Initial Public Offering (the “Public Warrants”) and the Private Placement Warrants are recognized as derivative liabilities in accordance with ASC 815-40. re-measurement
Offering Costs Associated with the Initial Public Offering	Offering Costs Associated with the Initial Public Offering Offering costs consisted of legal, accounting, and other costs incurred that were directly related to the Initial Public Offering. Offering costs are allocated to the separable financial instruments issued in the Initial Public Offering based on a relative fair value basis, compared to total proceeds received. Offering costs associated with warrant liabilities are expensed as incurred, presented as non-operating non-current	Offering Costs Associated with the Initial Public Offering Offering costs consisted of legal, accounting, underwriting fees and other costs incurred through the Initial Public Offering that were directly related to the Initial Public Offering. Offering costs were allocated to the separable financial instruments issued in the Initial Public Offering based on a relative fair value basis, compared to total proceeds received. Offering costs associated with derivative warrant liabilities were expensed as incurred and presented as non-operating expenses in the condensed consolidated statements of operations. Offering costs associated with issuance of the Class A ordinary shares were charged against the carrying value of the Class A ordinary shares subject to possible redemption upon the completion of the Initial Public Offering. The Company classifies deferred underwriting commissions as non-current liabilities as their liquidation is not reasonably expected to require the use of current assets or require the creation of current liabilities.
Class A Ordinary Shares Subject to Possible Redemption	Class A Ordinary Shares Subject to Possible Redemption The Company accounts for its Class A ordinary shares subject to possible redemption in accordance with the guidance in ASC Topic 480 “Distinguishing Liabilities from Equity.” Class A ordinary shares subject to mandatory redemption (if any) are classified as liability instruments and are measured at fair value. Conditionally redeemable Class A ordinary shares (including Class A ordinary shares that feature redemption rights that are either within the control of the holder or subject to redemption upon the occurrence of uncertain events not solely within the Company’s control) are classified as temporary equity. At all other times, Class A ordinary shares are classified as shareholders’ equity. The Company’s Class A ordinary shares feature certain redemption rights that are considered to be outside of the Company’s control and subject to the occurrence of uncertain future events. Accordingly, at December 31, 2020, 25,000,000 Class A ordinary shares subject to possible redemption are presented as temporary equity, outside of the shareholders’ equity section of the Company’s balance sheet. Immediately upon the closing of the Initial Public Offering, the Company recognized the remeasurement from initial book value to redemption amount. The change in the carrying value of Class A ordinary shares subject to possible redemption resulted in charges against additional paid-in	Class A Ordinary Shares Subject to Possible Redemption The Company accounts for its Class A ordinary shares subject to possible redemption in accordance with ASC 480. Class A ordinary shares subject to mandatory redemption (if any) is classified as liability instruments and are measured at fair value. Conditionally redeemable Class A ordinary shares (including Class A ordinary shares that feature redemption rights that are either within the control of the holder or subject to redemption upon the occurrence of uncertain events not solely within the Company’s control) are classified as temporary equity. At all other times, Class A ordinary shares are classified as shareholders’ equity. The Company’s Class A ordinary shares feature certain redemption rights that are considered to be outside of the Company’s control and subject to the occurrence of uncertain future events. Accordingly, as of September 30, 2021 and December 31, 2020, 25,000,000 Class A ordinary shares subject to possible redemption are presented at redemption value as temporary equity, outside of the shareholders’ equity section of the Company’s condensed balance sheet. There were no Class A ordinary shares issued or outstanding as of December 31, 2020. Effective with the closing of the Initial Public Offering, the Company recognized the accretion from initial book value to redemption amount, which resulted in charges against additional paid-in
Income Taxes	Income Taxes The Company follows the asset and liability method of accounting for income taxes under FASB ASC 740, “Income Taxes.” Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to differences between the financial statements carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that included the enactment date. Valuation allowances are established, when necessary, to reduce deferred tax assets to the amount expected to be realized. Deferred tax assets were deemed immaterial as of December 31, 2020. FASB ASC 740 prescribes a recognition threshold and a measurement attribute for the financial statement recognition and measurement of tax positions taken or expected to be taken in a tax return. For those benefits to be recognized, a tax position must be more likely than not to be sustained upon examination by taxing authorities. There were no unrecognized tax benefits as of December 31, 2020. The Company recognizes accrued interest and penalties related to unrecognized tax benefits as income tax expense. No amounts were accrued for the payment of interest and penalties as of December 31, 2020. The Company is currently not aware of any issues under review that could result in significant payments, accruals or material deviation from its position. The Company is subject to income tax examinations by major taxing authorities since inception.	Income Taxes The Company follows the asset and liability method of accounting for income taxes under FASB ASC Topic 740, “Income Taxes” (“ASC 740”). Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to differences between the financial statements carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that included the enactment date. Valuation allowances are established, when necessary, to reduce deferred tax assets to the amount expected to be realized. Deferred tax assets were deemed immaterial as of September 30, 2021. ASC 740 prescribes a recognition threshold and a measurement attribute for the financial statement recognition and measurement of tax positions taken or expected to be taken in a tax return. For those benefits to be recognized, a tax position must be more likely than not to be sustained upon examination by taxing authorities. There were no unrecognized tax benefits as of September 30, 2021. The Company recognizes accrued interest and penalties related to unrecognized tax benefits as income tax expense. No amounts were accrued for the payment of interest and penalties as of September 30, 2021. The Company is currently not aware of any issues under review that could result in significant payments, accruals or material deviation from its position. The Company is subject to income tax examinations by major taxing authorities since inception.
Net Loss Per Ordinary Share	Net Loss Per Ordinary Share The Company has two classes of shares, Class A ordinary shares and Class B ordinary shares. Income For the period from July 21, 2020 (inception) through December 31, 2020 Class A Class B (restated) Basic and diluted net loss per common share: Numerator: Allocation of net loss $ (2,374,665 ) $ (919,600 ) Denominator: Basic and diluted weighted average common shares outstanding 16,139,241 6,250,000 Basic and diluted net loss per common share $ (0.15 ) $ (0.15 )	Net Loss Per Ordinary Share The Company has two classes of shares, Class A ordinary shares and Class B ordinary shares. Income and losses are shared pro rata between the two classes of shares. Net loss per ordinary share is computed by dividing net loss by the weighted-average number of ordinary shares outstanding during the periods. The Company has not considered the effect of the warrants sold in the Initial Public Offering and the Private Placement to purchase an aggregate of 13,000,000, of the Company’s Class A ordinary shares in the calculation of diluted net loss per share, because their exercise is contingent upon further events and their inclusion would be anti-dilutive under the treasury stock method. As a result, diluted net loss per share is the same as basic net loss per share for the three and nine months ended September 30, 2021. The remeasurement adjustment on the Class A ordinary shares subject to possible redemption is excluded from earnings per share as the redemption value approximates fair value. For the Three Months Ended For the Nine Months Ended Class A Class B Class A Class B Basic and diluted net loss per common share: Numerator: Allocation of net loss $ (3,143,854 ) $ (785,964 ) $ (1,180,369 ) $ (295,092 ) Denominator: Basic and diluted weighted average common shares outstanding 25,000,000 6,250,000 25,000,000 6,250,000 Basic and diluted net loss per common share $ (0.13 ) $ (0.13 ) $ (0.05 ) $ (0.05 ) In connection with the change in presentation for the Class A ordinary shares subject to possible redemption, the Company has revised its earnings per share calculation to allocate income and losses shared pro rata between the two classes of shares. This presentation contemplates a Business Combination as the most likely outcome, in which case, both classes of shares participate pro rata in the income and losses of the Company. The impact to the reported amounts of weighted average shares outstanding and basic and diluted earnings per common share is presented below for the period from July 21, 2020 (inception) through September 30, 2020: For the period from Class A Class B (restated) Basic and diluted net loss per common share: Numerator: Allocation of net loss $ (293,337 ) $ (484,007 ) Denominator: Basic and diluted weighted average common shares outstanding 3,787,879 6,250,000 Basic and diluted net loss per common share $ (0.08 ) $ (0.08 )
Recent Accounting Standards	Recent Accounting Standards Management does not believe that any recently issued, but not yet effective, accounting standards if currently adopted would have a material effect on the Company’s financial statements.	Recent Adopted Accounting Standards In August 2020, the FASB issued Accounting Standards Update No. 2020-06, Debt-Debt with Conversion and Other Options (Subtopic 470-20) ’ s Own Equity (Subtopic 815-40): ’ s Own Equity 2020-06”), 2020-06 Recent Accounting Standards The Company’s management does not believe that any recently issued, but not yet effective, accounting standards if currently adopted would have a material effect

Restatement of Financial Stat_2

Restatement of Financial Statements (Tables)	5 Months Ended	9 Months Ended
	Dec. 31, 2020	Sep. 30, 2021
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Effect of Financial Statement Adjustments Related to Restatement		As of September 21, 2020 As Reported Adjustment As Restated Total assets $ 252,174,258 $ 252,174,258 Total liabilities $ 29,049,500 $ 29,049,500 Class A ordinary shares subject to possible redemption 218,124,750 31,875,250 250,000,000 Preference shares — — — Class A ordinary shares 319 (319 ) — Class B ordinary shares 719 — 719 Additional paid-in 5,747,460 (5,747,460 ) — Accumulated deficit (748,490 ) (26,127,471 ) (26,875,961 ) Total shareholders’ equity (deficit) $ 5,000,008 $ (31,875,250 ) $ (26,875,242 ) Total Liabilities, Class A Ordinary Shares Subject to Possible Redemption and Shareholders’ Equity (Deficit) $ 252,174,258 $ — $ 252,174,258 The impact of the restatement on the balance sheets and statements of shareholders’ equity for the Affected Quarterly and Annual Periods is presented below. The restatement had no impact on net income or net cash flows from operating, investing or financing activities. The tables below present the effect of the financial statement adjustments related to the restatement discussed above of the Company’s previously reported balance sheet and statements of shareholders’ equity as of September 30, 2020: As of September 30, 2020 As Reported Adjustment As Restated Total assets $ 252,167,049 $ 252,167,049 Total liabilities $ 29,066,145 $ 29,066,145 Class A ordinary shares subject to possible redemption 218,100,900 31,899,100 250,000,000 Preference shares — — — Class A ordinary shares 319 (319 ) — Class B ordinary shares 719 — 719 Additional paid-in 5,776,310 (5,776,310 ) — Accumulated deficit (777,344 ) (26,122,471 ) (26,899,815 ) Total shareholders’ equity (deficit) $ 5,000,004 $ (31,899,100 ) $ (26,899,096 ) Total Liabilities, Class A Ordinary Shares Subject to Possible Redemption and Shareholders’ Equity (Deficit) $ 252,167,049 $ — $ 252,167,049 Statement of changes in Stockholders’ equity As Previously Adjustment As Restated Sale of units in initial public offering, gross $ 237,500,000 $ (237,500,000 ) $ — Offering costs $ (13,646,752 ) 13,646,752 — Remeasurement of Class A ordinary shares subject to possible redemption — (26,146,752 ) (26,146,752 ) Shares subject to possible redemption 218,100,900 (218,100,900 ) — The tables below present the effect of the financial statement adjustments related to the restatement discussed above of the Company’s previously reported balance sheet and statement of shareholders’ equity as of December 31, 2020: As of December 31, 2020 As Reported Adjustment As Restated Total assets $ 250,827,490 $ 250,827,490 Total liabilities $ 30,243,507 $ 30,243,507 Class A ordinary shares subject to possible redemption 215,583,980 34,416,020 250,000,000 Preference shares — — — Class A ordinary shares 344 (344 ) — Class B ordinary shares 625 — 625 Additional paid-in 8,293,299 (8,293,299 ) — Accumulated deficit (3,294,265 ) (26,122,377 ) (29,416,642 ) Total shareholders’ equity (deficit) $ 5,000,003 $ (34,416,020 ) $ (29,416,017 ) Total Liabilities, Class A Ordinary Shares Subject to Possible Redemption and Shareholders’ Equity (Deficit) $ 250,827,490 $ — $ 250,827,490 Statement of changes in Stockholders’ equity As Previously Adjustment As Restated Sale of units in initial public offering, gross $ 237,500,000 $ (237,500,000 ) $ — Offering costs $ (13,646,752 ) 13,646,752 — Remeasurement of Class A ordinary shares subject to possible redemption — (26,146,752 ) (26,146,752 ) Shares subject to possible redemption (215,583,980 ) 215,583,980 — The tables below present the effect of the financial statement adjustments related to the restatement discussed above of the Company’s previously reported balance sheet and statement of shareholders’ equity as of March 31, 2021: As of March 31, 2021 As Previously Adjustment As Restated Total assets $ 250,663,379 $ 250,663,379 Total liabilities $ 20,840,433 $ 20,840,433 Class A ordinary shares subject to possible redemption 224,822,940 25,177,060 250,000,000 Preference shares — — — Class A ordinary shares 252 (252 ) — Class B ordinary shares 625 — 625 Additional paid-in — — — Accumulated deficit 4,999,129 (25,176,808 ) (20,177,679 ) Total shareholders’ equity (deficit) $ 5,000,006 $ (25,177,060 ) $ (20,177,054 ) Total Liabilities, Class A Ordinary Shares Subject to Possible Redemption and Shareholders’ Equity (Deficit) $ 250,663,379 $ — $ 250,663,379 For the three months ended March 31, 2021 As Previously Adjustment As Restated Shares subject to redemption $ (9,238,960 ) $ 9,238,960 $ — The tables below present the effect of the financi a e As of June 30, 2021 As Previously Adjustment As Restated Total assets $ 250,304,732 $ 250,304,732 Total liabilities $ 27,266,392 $ 27,266,392 Class A ordinary shares subject to possible redemption 218,038,330 31,961,670 250,000,000 Preference shares — — — Class A ordinary shares 320 (320 ) — Class B ordinary shares 625 — 625 Additional paid-in 6,784,542 (6,784,542 ) — Accumulated deficit (1,785,477 ) (25,176,808 ) (26,962,285 ) Total shareholders’ equity (deficit) $ 5,000,010 $ (31,961,670 ) $ (26,961,660 ) Total Liabilities, Class A Ordinary Shares Subject to Possible Redemption and Shareholders’ Equity (Deficit) $ 250,304,732 $ — $ 250,304,732 For the six months ended June 30, 2021 As Previously Adjustment As Restated Shares subject to redemption $ 6,784,610 $ (6,784,610 ) $ — In connection with the change in presentation for the Class A ordinary shares subject to possible redemption, the Company has restated its earnings per share calculation to allocate income and losses shared pro rata between the two classes of shares. This presentation contemplates a Business Combination as the most likely outcome, in which case, both classes of shares participate pro rata in the income and losses of the Company. The impact to the reported amounts of weighted average shares outstanding and basic and diluted earnings per common share is presented below for the Affected Quarterly and Annual Periods: EPS for Class A ordinary shares (redeemable) As Previously Adjustment As Restated Form 10-Q Earnings allocable to ordinary shares subject to possible redemption $ 3,321 $ 7,387,849 $ 7,391,170 Weighted average shares outstanding 21,568,664 3,431,336 25,000,000 Basic and diluted earnings per share $ — $ 0.30 $ 0.30 Form 10-Q Earnings (loss) allocable to ordinary shares subject to possible redemption $ 3,293 $ (5,430,978 ) $ (5,427,685 ) Weighted average shares outstanding 22,474,838 2,525,162 25,000,000 Basic and diluted earnings per share $ — $ (0.22 ) $ (0.22 ) Form 10-Q Earnings allocable to ordinary shares subject to possible redemption $ 6,514 $ 1,956,972 $ 1,963,486 Weighted average shares outstanding 22,024,254 2,975,746 25,000,000 Basic and diluted earnings per share $ — $ 0.08 $ 0.08 EPS for Class B ordinary shares (non-redeemable) As Previously Adjustment As Restated Form 10-Q Earnings allocable to non-redeemable ordinary shares $ 9,235,642 $ (7,387,849 ) $ 1,847,793 Weighted average shares outstanding 9,681,336 (3,431,336 ) 6,250,000 Basic and diluted earnings per share $ 0.95 $ (0.65 ) $ 0.30 Form 10-Q Loss allocable to non-redeemable ordinary shares $ (6,787,899 ) $ 5,430,978 $ (1,356,921 ) Weighted average shares outstanding 8,775,162 (2,525,162 ) 6,250,000 Basic and diluted earnings per share $ (0.77 ) $ 0.55 $ (0.22 ) Form 10-Q Earnings allocable to non-redeemable ordinary shares $ 2,447,843 $ (1,956,972 ) $ 490,871 Weighted average shares outstanding 9,225,746 (2,975,746 ) 6,250,000 Basic and diluted earnings per share $ 0.27 $ (0.19 ) $ 0.08 EPS for Class A ordinary shares (redeemable) As Previously Adjustment As Restated Form 10-Q Earnings (loss) allocable to ordinary shares subject to possible redemption $ 3,841 $ (2,378,506 ) $ (2,374,665 ) Weighted average shares outstanding 21,810,415 (18,022,536 ) 3,787,879 Basic and diluted earnings per share $ — $ (0.08 ) $ (0.08 ) Form 10-K/A Earnings (loss) allocable to ordinary shares subject to possible redemption $ — $ (293,337 ) $ (293,337 ) Weighted average shares outstanding 21,719,426 (5,580,185 ) 16,139,241 Basic and diluted earnings per share $ — $ (0.15 ) $ (0.15 ) EPS for Class B ordinary shares (non- As Previously Adjustment As Restated Form 10-Q (September 30, 2020) - the period from July 21, 2020 (inception) through September 30, 2020 Loss allocable to non-redeemable ordinary shares $ (777,344 ) $ 293,337 $ (484,007 ) Weighted average shares outstanding 6,732,994 (482,994 ) 6,250,000 Basic and diluted earnings per share $ (0.12 ) $ 0.04 $ (0.08 ) Form 10-K/A (December 31, 2020) - the period from July 21, 2020 (inception) through December 31, 2020 Loss allocable to non-redeemable ordinary shares $ (3,298,105 ) $ 2,378,505 $ (919,600 ) Weighted average shares outstanding 8,310,766 (2,060,766 ) 6,250,000 Basic and diluted earnings per share $ (0.40 ) $ 0.25 $ (0.15 )
ACON S2 Acquisition Corp [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Effect of Financial Statement Adjustments Related to Restatement	The tables below present the effect of the financial statement adjustments related to the restatement discussed above of the Company’s previously reported financial statements as of and for the period from July 21, 2020 (inception) through December 31, 2020: As of December 31, 2020 As Previously Restatement As Restated Balance Sheet Total assets $ 250,827,490 $ — $ 250,827,490 Liabilities and shareholders’ equity Total current liabilities $ 139,107 $ — $ 139,107 Deferred underwriting commissions 8,750,000 — 8,750,000 Derivative warrant liabilities — 21,354,400 21,354,400 Total liabilities 8,889,107 21,354,400 30,243,507 Class A ordinary share, $0.0001 par value; shares subject to possible redemption 236,938,380 (21,354,400 ) 215,583,980 Shareholders’ equity Preference shares—$0.0001 par value — — — Class A ordinary shares—$0.0001 par value 131 213 344 Class B ordinary shares—$0.0001 par value 625 — 625 Additional paid-in-capital 5,703,622 2,589,677 8,293,299 Accumulated deficit (704,375 ) (2,589,890 ) (3,294,265 ) Total shareholders’ equity 5,000,003 — 5,000,003 Total liabilities and shareholders’ equity $ 250,827,490 $ — $ 250,827,490 Period From July 21, 2020 (Inception) Through As Previously Restatement As Restated Statement of Operations Loss from operations $ (708,829 ) $ — $ (708,829 ) Other (expense) income: Change in fair value of derivative warrant liabilities — (1,854,400 ) (1,854,400 ) Financing costs—derivative warrant liabilities — (735,490 ) (735,490 ) Gain on marketable securities (net), and dividends held in Trust Account 4,454 — 4,454 Total other (expense) income 4,454 (2,589,890 ) (2,585,436 ) Net loss $ (704,375 ) $ (2,589,890 ) $ (3,294,265 ) Basic and Diluted weighted-average Class A ordinary share outstanding 23,734,800 21,719,426 Basic and Diluted net income per Class A ordinary shares $ 0.00 $ — Basic and Diluted weighted-average Class B ordinary share outstanding 7,052,256 8,310,766 Basic and Diluted net loss per Class B ordinary shares $ (0.10 ) $ (0.40 ) Period From July 21, 2020 (Inception) Through As Previously Restatement As Restated Statement of Cash Flows Net loss $ (704,375 ) $ (2,589,890 ) $ (3,294,265 ) Adjustments to reconcile net loss to net cash used in operating activities 11,546 2,589,890 2,601,436 Net cash used in operating activities (976,685 ) — (976,685 ) Net cash used in investing activities (250,000,000 ) — (250,000,000 ) Net cash provided by financing activities 251,446,758 — 251,446,758 Net change in cash $ 470,073 $ — $ 470,073 As of September 21, 2020 As Reported, As Restated Adjustment As Restated Balance Sheet Total assets $ 252,174,258 $ — $ 252,174,258 Total liabilities $ 29,049,500 $ — $ 29,049,500 Class A ordinary shares subject to possible redemption 218,124,750 31,875,250 250,000,000 Preference shares — — — Class A ordinary shares 319 (319 ) — Class B ordinary shares 719 — 719 Additional paid-in 5,747,460 (5,747,460 ) — Accumulated deficit (748,490 ) (26,127,471 ) (26,875,961 ) Total shareholders’ equity (deficit) $ 5,000,008 $ (31,875,250 ) $ (26,875,242 ) Total Liabilities, Class A Ordinary Shares Subject to Possible Redemption and Shareholders’ Equity (Deficit) $ 252,174,258 $ — $ 252,174,258 The table below presents the effect of the financial statement adjustments related to the restatement discussed above of the Company’s previously reported financial statements as of December 31, 2020 and for the period from July 21, 2020 (inception) through December 31, 2020: As of December 31, 2020 As Previously Restatement As Restated Balance Sheet Total assets $ 250,827,490 $ — $ 250,827,490 Total liabilities 30,243,507 — 30,243,507 Class A ordinary shares subject to possible redemption 215,583,980 34,416,020 250,000,000 Shareholders’ equity Preference shares - $0.0001 par value — — — Class A ordinary shares - $0.0001 par value 344 (344 ) — Class B ordinary shares - $0.0001 par value 625 — 625 Additional paid-in-capital 8,293,299 (8,293,299 ) — Accumulated deficit (3,294,265 ) (26,122,377 ) (29,416,642 ) Total shareholders’ equity 5,000,003 (34,416,020 ) (29,416,017 ) Total liabilities and shareholders’ equity $ 250,827,490 $ — $ 250,827,490 Period From July 21, 2020 (Inception) Through As Previously Restatement As Restated Statement of Operations Earnings (loss) allocable to ordinary shares subject to possible redemption $ 3,841 (2,378,506 ) $ (2,374,665 ) Basic and Diluted weighted-average Class A ordinary share outstanding 21,719,416 (5,580,185 ) 16,139,241 Basic and Diluted net income per Class A ordinary shares $ 0.00 (0.15 ) $ (0.15 ) Loss allocable to non-redeemable ordinary shares $ (3,298,105 ) 2,378,505 $ (919,600 ) Basic and Diluted weighted-average Class B ordinary share outstanding 8,310,766 (2,060,766 ) 6,250,000 Basic and Diluted net loss per Class B ordinary shares $ (0.40 ) 0.25 $ (0.15 ) Period From July 21, 2020 (Inception) Through As Previously Restatement As Restated Statement of Shareholders’ Deficit Sale of units in initial public offering, gross $ 237,500,000 $ (237,500,000 ) $ — Offering costs (13,646,752 ) 13,646,752 — Remeasurement of Class A ordinary shares subject to possible redemption — (26,146,471 ) (26,146,471 ) Shares subject to possible redemption (215,583,980 ) 215,583,980 —
Schedule of Unaudited Quarterly Financial Information for Restatement and Revision	The following tables contain unaudited quarterly financial information for the quarterly period ended September 30, 2020 that has been updated to reflect the restatement of the Company’s financial statements. As of September 30, 2020 As Previously Restatement As Restated Unaudited Condensed Balance Sheet Total assets $ 252,167,049 $ — $ 252,167,049 Liabilities and shareholders’ equity Total current liabilities $ 816,145 $ — $ 816,145 Deferred underwriting commissions 8,750,000 — 8,750,000 Derivative warrant liabilities — 19,500,000 19,500,000 Total liabilities 9,566,145 19,500,000 29,066,145 Class A ordinary share, $0.0001 par value; shares subject to possible redemption 237,600,900 (19,500,000 ) 218,100,900 Shareholders’ equity Preference shares—$0.0001 par value — — — Class A ordinary shares—$0.0001 par value 124 195 319 Class B ordinary shares—$0.0001 par value 719 — 719 Additional paid-in-capital 5,041,015 735,295 5,776,310 Accumulated deficit (41,854 ) (735,490 ) (777,344 ) Total shareholders’ equity 5,000,004 — 5,000,004 Total liabilities and shareholders’ equity $ 252,167,049 $ — $ 252,167,049 Period From July 21, 2020 (Inception) Through As Restatement As Restated Unaudited Condensed Statement of Operations Loss from operations $ (41,854 ) $ — $ (41,854 ) Other (expense) income: Change in fair value of derivative warrant liabilities — — — Financing costs—derivative warrant liabilities — (735,490 ) (735,490 ) Total other (expense) income — (735,490 ) (735,490 ) Net loss $ (41,854 ) $ (735,490 ) $ (777,344 ) Basic and Diluted weighted-average Class A ordinary share outstanding — 21,810,415 Basic and Diluted net income per Class A ordinary shares $ — $ — Basic and Diluted weighted-average Class B ordinary share outstanding 6,437,865 6,732,994 Basic and Diluted net loss per Class B ordinary shares $ (0.01 ) $ (0.12 ) Period From July 21, 2020 (Inception) Through As Previously Restatement As Restated Unaudited Condensed Statement of Cash Flows Net loss $ (41,854 ) $ (735,490 ) $ (777,344 ) Adjustment to reconcile net loss to net cash used in operating activities 16,000 735,490 751,490 Net cash used in operating activities (26,800 ) — (26,800 ) Net cash used in investing activities (250,000,000 ) — (250,000,000 ) Net cash provided by financing activities 251,773,258 — 251,773,258 Net change in cash $ 1,746,458 $ — $ 1,746,458 As of September 30, 2020 As Previously Restatement As Restated Unaudited Condensed Balance Sheet Total assets $ 252,167,049 $ — $ 252,167,049 Total liabilities 29,066,145 — 29,066,145 Class A ordinary share, $0.0001 par value; shares subject to possible redemption 218,100,900 31,899,100 250,000,000 Shareholders’ equity Preference shares - $0.0001 par value — — — Class A ordinary shares - $0.0001 par value 319 (319 ) — Class B ordinary shares - $0.0001 par value 719 — 719 Additional paid-in-capital 5,776,310 (5,776,310 ) — Accumulated deficit (777,344 ) (26,122,471 ) (26,899,815 ) Total shareholders’ equity 5,000,004 (31,899,100 ) (26,899,096 ) Total liabilities and shareholders’ equity $ 252,167,049 $ — $ 252,167,049 Period From July 21, 2020 (Inception) Through As Previously Restatement As Restated Unaudited Statement of Operations Earnings (loss) allocable to ordinary shares subject to possible redemption $ — (293,337 ) $ (293,337 ) Basic and Diluted weighted-average Class A ordinary share outstanding 21,810,415 (18,022,536 ) 3,787,879 Basic and Diluted net income (loss) per Class A ordinary shares $ — (0.08 ) $ (0.08 ) Loss allocable to non-redeemable ordinary shares $ (777,344 ) 293,337 $ (484,007 ) Basic and Diluted weighted-average Class B ordinary share outstanding 6,732,994 (482,994 ) 6,250,000 Basic and Diluted net loss per Class B ordinary shares $ (0.12 ) 0.04 $ (0.08 ) Period From July 21, 2020 (Inception) Through As Previously Restatement As Restated Statement of Shareholders’ Deficit Sale of units in initial public offering, gross $ 237,500,000 $ (237,500,000 ) $ — Offering costs (13,646,752 ) 13,646,752 — Remeasurement of Class A ordinary shares subject to possible redemption — (26,146,471 ) (26,146,471 ) Shares subject to possible redemption 218,124,750 (218,124,750 ) —

Restatement of Previously Iss_2

Restatement of Previously Issued Financial Statements (Table)	9 Months Ended
	Sep. 30, 2021
Accounting Standards Update and Change in Accounting Principle [Abstract]
Summary of Financial Statement Adjustments Related to Restatement	As of September 21, 2020 As Reported Adjustment As Restated Total assets $ 252,174,258 $ 252,174,258 Total liabilities $ 29,049,500 $ 29,049,500 Class A ordinary shares subject to possible redemption 218,124,750 31,875,250 250,000,000 Preference shares — — — Class A ordinary shares 319 (319 ) — Class B ordinary shares 719 — 719 Additional paid-in 5,747,460 (5,747,460 ) — Accumulated deficit (748,490 ) (26,127,471 ) (26,875,961 ) Total shareholders’ equity (deficit) $ 5,000,008 $ (31,875,250 ) $ (26,875,242 ) Total Liabilities, Class A Ordinary Shares Subject to Possible Redemption and Shareholders’ Equity (Deficit) $ 252,174,258 $ — $ 252,174,258 The impact of the restatement on the balance sheets and statements of shareholders’ equity for the Affected Quarterly and Annual Periods is presented below. The restatement had no impact on net income or net cash flows from operating, investing or financing activities. The tables below present the effect of the financial statement adjustments related to the restatement discussed above of the Company’s previously reported balance sheet and statements of shareholders’ equity as of September 30, 2020: As of September 30, 2020 As Reported Adjustment As Restated Total assets $ 252,167,049 $ 252,167,049 Total liabilities $ 29,066,145 $ 29,066,145 Class A ordinary shares subject to possible redemption 218,100,900 31,899,100 250,000,000 Preference shares — — — Class A ordinary shares 319 (319 ) — Class B ordinary shares 719 — 719 Additional paid-in 5,776,310 (5,776,310 ) — Accumulated deficit (777,344 ) (26,122,471 ) (26,899,815 ) Total shareholders’ equity (deficit) $ 5,000,004 $ (31,899,100 ) $ (26,899,096 ) Total Liabilities, Class A Ordinary Shares Subject to Possible Redemption and Shareholders’ Equity (Deficit) $ 252,167,049 $ — $ 252,167,049 Statement of changes in Stockholders’ equity As Previously Adjustment As Restated Sale of units in initial public offering, gross $ 237,500,000 $ (237,500,000 ) $ — Offering costs $ (13,646,752 ) 13,646,752 — Remeasurement of Class A ordinary shares subject to possible redemption — (26,146,752 ) (26,146,752 ) Shares subject to possible redemption 218,100,900 (218,100,900 ) — The tables below present the effect of the financial statement adjustments related to the restatement discussed above of the Company’s previously reported balance sheet and statement of shareholders’ equity as of December 31, 2020: As of December 31, 2020 As Reported Adjustment As Restated Total assets $ 250,827,490 $ 250,827,490 Total liabilities $ 30,243,507 $ 30,243,507 Class A ordinary shares subject to possible redemption 215,583,980 34,416,020 250,000,000 Preference shares — — — Class A ordinary shares 344 (344 ) — Class B ordinary shares 625 — 625 Additional paid-in 8,293,299 (8,293,299 ) — Accumulated deficit (3,294,265 ) (26,122,377 ) (29,416,642 ) Total shareholders’ equity (deficit) $ 5,000,003 $ (34,416,020 ) $ (29,416,017 ) Total Liabilities, Class A Ordinary Shares Subject to Possible Redemption and Shareholders’ Equity (Deficit) $ 250,827,490 $ — $ 250,827,490 Statement of changes in Stockholders’ equity As Previously Adjustment As Restated Sale of units in initial public offering, gross $ 237,500,000 $ (237,500,000 ) $ — Offering costs $ (13,646,752 ) 13,646,752 — Remeasurement of Class A ordinary shares subject to possible redemption — (26,146,752 ) (26,146,752 ) Shares subject to possible redemption (215,583,980 ) 215,583,980 — The tables below present the effect of the financial statement adjustments related to the restatement discussed above of the Company’s previously reported balance sheet and statement of shareholders’ equity as of March 31, 2021: As of March 31, 2021 As Previously Adjustment As Restated Total assets $ 250,663,379 $ 250,663,379 Total liabilities $ 20,840,433 $ 20,840,433 Class A ordinary shares subject to possible redemption 224,822,940 25,177,060 250,000,000 Preference shares — — — Class A ordinary shares 252 (252 ) — Class B ordinary shares 625 — 625 Additional paid-in — — — Accumulated deficit 4,999,129 (25,176,808 ) (20,177,679 ) Total shareholders’ equity (deficit) $ 5,000,006 $ (25,177,060 ) $ (20,177,054 ) Total Liabilities, Class A Ordinary Shares Subject to Possible Redemption and Shareholders’ Equity (Deficit) $ 250,663,379 $ — $ 250,663,379 For the three months ended March 31, 2021 As Previously Adjustment As Restated Shares subject to redemption $ (9,238,960 ) $ 9,238,960 $ — The tables below present the effect of the financi a e As of June 30, 2021 As Previously Adjustment As Restated Total assets $ 250,304,732 $ 250,304,732 Total liabilities $ 27,266,392 $ 27,266,392 Class A ordinary shares subject to possible redemption 218,038,330 31,961,670 250,000,000 Preference shares — — — Class A ordinary shares 320 (320 ) — Class B ordinary shares 625 — 625 Additional paid-in 6,784,542 (6,784,542 ) — Accumulated deficit (1,785,477 ) (25,176,808 ) (26,962,285 ) Total shareholders’ equity (deficit) $ 5,000,010 $ (31,961,670 ) $ (26,961,660 ) Total Liabilities, Class A Ordinary Shares Subject to Possible Redemption and Shareholders’ Equity (Deficit) $ 250,304,732 $ — $ 250,304,732 For the six months ended June 30, 2021 As Previously Adjustment As Restated Shares subject to redemption $ 6,784,610 $ (6,784,610 ) $ — In connection with the change in presentation for the Class A ordinary shares subject to possible redemption, the Company has restated its earnings per share calculation to allocate income and losses shared pro rata between the two classes of shares. This presentation contemplates a Business Combination as the most likely outcome, in which case, both classes of shares participate pro rata in the income and losses of the Company. The impact to the reported amounts of weighted average shares outstanding and basic and diluted earnings per common share is presented below for the Affected Quarterly and Annual Periods: EPS for Class A ordinary shares (redeemable) As Previously Adjustment As Restated Form 10-Q Earnings allocable to ordinary shares subject to possible redemption $ 3,321 $ 7,387,849 $ 7,391,170 Weighted average shares outstanding 21,568,664 3,431,336 25,000,000 Basic and diluted earnings per share $ — $ 0.30 $ 0.30 Form 10-Q Earnings (loss) allocable to ordinary shares subject to possible redemption $ 3,293 $ (5,430,978 ) $ (5,427,685 ) Weighted average shares outstanding 22,474,838 2,525,162 25,000,000 Basic and diluted earnings per share $ — $ (0.22 ) $ (0.22 ) Form 10-Q Earnings allocable to ordinary shares subject to possible redemption $ 6,514 $ 1,956,972 $ 1,963,486 Weighted average shares outstanding 22,024,254 2,975,746 25,000,000 Basic and diluted earnings per share $ — $ 0.08 $ 0.08 EPS for Class B ordinary shares (non-redeemable) As Previously Adjustment As Restated Form 10-Q Earnings allocable to non-redeemable ordinary shares $ 9,235,642 $ (7,387,849 ) $ 1,847,793 Weighted average shares outstanding 9,681,336 (3,431,336 ) 6,250,000 Basic and diluted earnings per share $ 0.95 $ (0.65 ) $ 0.30 Form 10-Q Loss allocable to non-redeemable ordinary shares $ (6,787,899 ) $ 5,430,978 $ (1,356,921 ) Weighted average shares outstanding 8,775,162 (2,525,162 ) 6,250,000 Basic and diluted earnings per share $ (0.77 ) $ 0.55 $ (0.22 ) Form 10-Q Earnings allocable to non-redeemable ordinary shares $ 2,447,843 $ (1,956,972 ) $ 490,871 Weighted average shares outstanding 9,225,746 (2,975,746 ) 6,250,000 Basic and diluted earnings per share $ 0.27 $ (0.19 ) $ 0.08 EPS for Class A ordinary shares (redeemable) As Previously Adjustment As Restated Form 10-Q Earnings (loss) allocable to ordinary shares subject to possible redemption $ 3,841 $ (2,378,506 ) $ (2,374,665 ) Weighted average shares outstanding 21,810,415 (18,022,536 ) 3,787,879 Basic and diluted earnings per share $ — $ (0.08 ) $ (0.08 ) Form 10-K/A Earnings (loss) allocable to ordinary shares subject to possible redemption $ — $ (293,337 ) $ (293,337 ) Weighted average shares outstanding 21,719,426 (5,580,185 ) 16,139,241 Basic and diluted earnings per share $ — $ (0.15 ) $ (0.15 ) EPS for Class B ordinary shares (non- As Previously Adjustment As Restated Form 10-Q (September 30, 2020) - the period from July 21, 2020 (inception) through September 30, 2020 Loss allocable to non-redeemable ordinary shares $ (777,344 ) $ 293,337 $ (484,007 ) Weighted average shares outstanding 6,732,994 (482,994 ) 6,250,000 Basic and diluted earnings per share $ (0.12 ) $ 0.04 $ (0.08 ) Form 10-K/A (December 31, 2020) - the period from July 21, 2020 (inception) through December 31, 2020 Loss allocable to non-redeemable ordinary shares $ (3,298,105 ) $ 2,378,505 $ (919,600 ) Weighted average shares outstanding 8,310,766 (2,060,766 ) 6,250,000 Basic and diluted earnings per share $ (0.40 ) $ 0.25 $ (0.15 )

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	5 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2020	Sep. 30, 2021	Dec. 31, 2020
Schedule of Earnings Per Share, Basic and Diluted		The following table presents the calculation of basic and diluted net loss per share attributable to common shareholders (in thousands, except per share data): Three Months Ended 2021 2020 Net loss $ (51,325 ) $ (2,771 ) Weighted-average shares outstanding – Basic and Diluted 8,823,458 7,102,536 Net loss per share - Basic and Diluted $ (5.82 ) $ (0.39 ) Nine Months Ended 2021 2020 Net loss $ (296,685 ) $ (6,200 ) Weighted-average shares outstanding – Basic and Diluted 8,458,054 7,099,532 Net loss per share - Basic and Diluted $ (35.08 ) $ (0.87 )	The following table presents the calculation of basic and diluted net loss per share attributable to common shareholders for the years ended December 31, 2020 and 2019 (in thousands, except per share data): 2020 2019 Net loss $ (30,419 ) $ (11,467 ) Series B Redeemable Convertible Preferred Stock accretion — (79 ) Net Loss to Common Stockholders $ (30,419 ) $ (11,546 ) Weighted-average shares outstanding – Basic and Diluted 7,108,389 7,043,575 Net loss per share – Basic and Diluted $ (4.28 ) $ (1.64 )
ACON S2 Acquisition Corp [Member]
Schedule of Earnings Per Share, Basic and Diluted	For the period from July 21, 2020 (inception) through December 31, 2020 Class A Class B (restated) Basic and diluted net loss per common share: Numerator: Allocation of net loss $ (2,374,665 ) $ (919,600 ) Denominator: Basic and diluted weighted average common shares outstanding 16,139,241 6,250,000 Basic and diluted net loss per common share $ (0.15 ) $ (0.15 )	For the Three Months Ended For the Nine Months Ended Class A Class B Class A Class B Basic and diluted net loss per common share: Numerator: Allocation of net loss $ (3,143,854 ) $ (785,964 ) $ (1,180,369 ) $ (295,092 ) Denominator: Basic and diluted weighted average common shares outstanding 25,000,000 6,250,000 25,000,000 6,250,000 Basic and diluted net loss per common share $ (0.13 ) $ (0.13 ) $ (0.05 ) $ (0.05 ) For the period from Class A Class B (restated) Basic and diluted net loss per common share: Numerator: Allocation of net loss $ (293,337 ) $ (484,007 ) Denominator: Basic and diluted weighted average common shares outstanding 3,787,879 6,250,000 Basic and diluted net loss per common share $ (0.08 ) $ (0.08 )

Customer Deposits (Tables)

Customer Deposits (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Summary of Rollforward of Contract Balances	The following table is a rollforward of customer deposits balances for the nine months ended September 30, 2021 and twelve months ended December 31, 2020 (in thousands): September 30, December 31, Customer deposits, beginning balance $ 2,258 $ 2,207 Additions 850 506 Cancellations — (455 ) Customer deposits, ending balance $ 3,108 $ 2,258	The following table is a rollforward of contract balances as of December 31, 2020 and 2019 (in thousands): 2020 2019 Customer deposits - beginning balance $ 2,207 $ 869 Additions 506 1,983 Cancellations (455 ) (645 ) Customer deposits - ending balance $ 2,258 $ 2,207

Loss Per Share (Tables)

Loss Per Share (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Earnings Per Share [Abstract]
Summary of Basic and Diluted Net Loss Per Share	The following table presents the calculation of basic and diluted net loss per share attributable to common shareholders (in thousands, except per share data): Three Months Ended 2021 2020 Net loss $ (51,325 ) $ (2,771 ) Weighted-average shares outstanding – Basic and Diluted 8,823,458 7,102,536 Net loss per share - Basic and Diluted $ (5.82 ) $ (0.39 ) Nine Months Ended 2021 2020 Net loss $ (296,685 ) $ (6,200 ) Weighted-average shares outstanding – Basic and Diluted 8,458,054 7,099,532 Net loss per share - Basic and Diluted $ (35.08 ) $ (0.87 )	The following table presents the calculation of basic and diluted net loss per share attributable to common shareholders for the years ended December 31, 2020 and 2019 (in thousands, except per share data): 2020 2019 Net loss $ (30,419 ) $ (11,467 ) Series B Redeemable Convertible Preferred Stock accretion — (79 ) Net Loss to Common Stockholders $ (30,419 ) $ (11,546 ) Weighted-average shares outstanding – Basic and Diluted 7,108,389 7,043,575 Net loss per share – Basic and Diluted $ (4.28 ) $ (1.64 )
Summary of Diluted Weighted Average Common Shares	share equivalent securities have been excluded from the calculation of diluted weighted-average common shares outstanding because the effect is anti-dilutive for the periods presented: Three Months Ended 2021 2020 Stock options 2,792,655 3,562,417 Redeemable convertible preferred stock 38,768,389 32,865,949 Warrants — 1,738,382 41,561,044 38,166,748 Nine Months Ended 2021 2020 Stock options 2,792,655 3,562,417 Redeemable convertible preferred stock 38,768,389 32,865,949 Warrants — 1,738,382 41,561,044 38,166,748	The following outstanding balances of common share equivalent securities have been excluded from the calculation of diluted weighted-average common shares outstanding because the effect is anti-dilutive for the periods presented: 2020 2019 Stock options 3,891,768 2,104,223 Preferred stock 32,865,949 32,865,949 Warrants 1,738,382 1,668,382 38,496,099 36,638,554

Prepaid Expenses And Other Cu_2

Prepaid Expenses And Other Current Assets (Tables)	12 Months Ended
	Dec. 31, 2020
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Summary of Prepaid Expenses and Other Current Assets	Prepaid expenses and other current assets consist of the following as of December 31, 2020 and 2019 (in thousands): 2020 2019 Vendor advances $ 473 $ 507 IT services and other office expenses 157 50 Insurance 107 41 Other 56 60 Total prepaids and other current assets $ 793 $ 658

Property And Equipment, Net (Ta

Property And Equipment, Net (Tables)	12 Months Ended
	Dec. 31, 2020
Property, Plant and Equipment [Abstract]
Summary of Property and Equipment	Property and equipment, net consist of the following as of December 31, 2020 and 2019 (in thousands): 2020 2019 Machinery and equipment $ 2,217 $ 1,430 Furniture and fixtures 90 60 Leasehold improvements 677 496 Construction in process — 389 Total property and equipment 2,984 2,375 Less accumulated depreciation (1,148 ) (712 ) Total property and equipment, net $ 1,836 $ 1,663

Accrued and Other Current Lia_2

Accrued and Other Current Liabilities (Tables)	12 Months Ended
	Dec. 31, 2020
Payables and Accruals [Abstract]
Summary of Accrued and Other Current Liabilities	Accrued and other current liabilities consist of the following as of December 31, 2020 and 2019 (in thousands): 2020 2019 Payroll and related benefits $ 777 $ 351 Materials and related purchases 464 474 Deferred rent 462 524 Professional & consulting fees 248 103 Customer refund — 352 Other 243 22 Total accrued and other current liabilities $ 2,194 $ 1,826

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Summary of Future Minimum Lease Payments Under Non-cancelable Operating Lease Agreements	The future minimum lease payments under non-cancelable 2021 $ 840 2022 865 2023 891 2024 917 2025 157 Future Operating Lease Payments $ 3,670

Borrowings (Tables)

Borrowings (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Debt Disclosure [Abstract]
Summary of Long Term Debt	Long-term debt consists of the following as of September 30, 2021 and December 31, 2020 (in thousands): September 30, December 31, Notes payable $ 4,236 $ 4,761 Bridge loan 21,432 — PPP loan — 936 Total notes payable 25,668 5,697 Less notes payable, current 23,415 5,678 Notes payable, non-current $ 2,253 $ 19	Long term debt consists of the following as of December 2020 2019 Notes payable $ 4,761 $ 828 PPP loan 936 — Total notes payable 5,697 828 Less current portion of notes payable 5,678 365 Long-term notes payable, net of current portion $ 19 $ 463
Summary of Maturities of Long Term Debt		As of December 31, 2020, principal payments on the Company’s term loan for equipment, are scheduled as follows for the fiscal year ending December 31 (in thousands): 2021 $ 48 2022 18 2023 1 Total principal payments on notes payable $ 67

Class A Ordinary Shares Subje_2

Class A Ordinary Shares Subject to Possible Redemption (Tables)	5 Months Ended	9 Months Ended
	Dec. 31, 2020	Sep. 30, 2021
ACON S2 Acquisition Corp [Member]
Summary of recognized in Class A ordinary shares subject to possible redemption	The Class A ordinary shares issued in the Initial Public Offering were recognized in Class A ordinary shares subject to possible redemption as recorded outside of permanent equity as follows: Gross Proceeds $ 250,000,000 Less: Offering costs allocated to Class A shares subject to possible redemption (13,646,752 ) Proceeds allocated to Public Warrants at issuance (12,500,000 ) Plus: Remeasurement adjustment on Class A ordinary shares subject to possible redemption 26,146,752 Class A ordinary shares subject to possible redemption $ 250,000,000	The Class A ordinary shares issued in the Initial Public Offering were recognized in Class A ordinary shares subject to possible redemption as recorded outside of permanent equity as follows: Gross Proceeds $ 250,000,000 Less: — Offering costs allocated to Class A shares subject to possible redemption (13,646,752 ) Proceeds allocated to Public Warrants at issuance (12,500,000 ) Plus: Remeasure adjustment on Class A ordinary shares subject to possible redemption amount 26,146,752 Class A ordinary shares subject to possible redemption $ 250,000,000

Redeemable Convertible Prefer_2

Redeemable Convertible Preferred Stock (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Temporary Equity Disclosure [Abstract]
Summary of The Company's Redeemable Convertible Preferred Stock	The Company’s Redeemable Convertible Preferred Stock as of September 30, 2021 consisted of the following (in thousands, except share data): Shares Shares Issued and Issuance Net Carrying Aggregate Series A 5,941,109 5,941,109 $ 0.56 $ 3,228 $ 3,321 Series B 12,011,923 12,005,442 1.23 30,659 14,748 Series C-1 16,345,688 16,335,705 1.84 19,178 30,098 Series C-2 27,773,344 4,486,133 2.95 37,008 13,225 62,072,064 38,768,389 $ 90,073 $ 61,392	The Company’s Redeemable Convertible Preferred Stock as of December 31, 2020 consisted of (in thousands, except share data): Shares Shares Issued Issuance Net Carrying Aggregate Series A 5,941,109 5,941,109 $ 0.56 $ 3,228 $ 3,321 Series B 12,011,923 10,649,152 1.22848 12,746 13,082 Series C- 16,345,688 16,275,688 1.84248 18,398 29,988 Series C- 27,137,317 — — — — 61,436,037 32,865,949 $ 34,372 $ 46,391
Summary of Series C-2 Redeemable Convertible Preferred Stock Purchase Right and Related Warrants	The number of shares subject to and potential proceeds from the C-2 C-2 As of September 30, 2021 Quantity Price Proceeds Series C-2 23,236,328 $ 2.95 $ 68,499,998 As of September 30, 2021 Upon Completion of SPAC merger Quantity Price Proceeds Series C-2 5,427,464 $ 2.95 $ 16,000,000 Series C-2 14,365,207 0.0001 1,437 Total Proceeds Upon Exercise $ 16,001,437 As of September 30, 2021 Milestones without SPAC merger Quantity Price Proceeds Series C-2 22,897,111 $ 2.95 $ 67,499,996
Summary of The Company Periodically Issues Warrants In Conjunction With The Issuance Of Preferred Stock Or debt	The Company periodically issues warrants in conjunction with the issuance of preferred stock or debt. As of September 30, 2021, and December 31, 2020, the following warrants were outstanding: September 30, December 31, Common Stock Warrants — 305,611 Series B Preferred Warrants — 1,362,771 Series C Preferred Warrants — 70,000 Total Warrants — 1,738,382	The Company periodically issues warrants in conjunction with the issuance of preferred stock or debt. As of December 31, the following warrants were outstanding: 2020 2019 Common Stock Warrants 305,611 305,611 Series B Preferred Warrants 1,362,771 1,362,771 Series C Preferred Warrants 70,000 — Total Warrants 1,738,382 1,668,382
Summary of The Warrant Activities	The table below shows the warrant activities during the nine months ended September 30, 2021: December 31, Issued Exercised September 30, Common Stock Warrants 305,611 — 305,611 — Series B Preferred Stock Warrants 1,362,771 — 1,362,771 — Series C Preferred Stock Warrants 70,000 585,145 655,145 — Total Warrants 1,738,382 585,145 2,323,527 —
Summary of The Warrants Were Valued Using The Following Assumptions	The table below shows the valuation assumptions for the warrants immediately prior to the exercises as of and for the nine months ended September 30, 2021: As of and for nine months ended September 30, 2021 Common Series B Series C-1 Series C-2 Expected volatility N/A 80% 80% 80% Expected term (in years) N/A 2 2 2 Risk-free interest rate N/A 0.16% - 0.28% 0.16% - 0.28% 0.16% - 0.28% Dividend yield N/A 0% 0% 0% The warrants were valued using the following assumptions as of December 31, 2020: As of December 31, 2020 Common Series B Series C-1 Series C-2 Expected volatility N/A 80 % 80 % N/A Expected term (in years) N/A 2 2 N/A Risk-free interest rate N/A 0.13 % 0.13 % N/A Dividend yield N/A 0 % 0 % N/A	The warrants were valued using the following assumptions: At issuance date Common Preferred B Preferred C-1 Expected volatility 80 % 80 % 80 % Expected term (in years) 5.00 5.00 3.75 Risk-free interest rate 2.20 % 2.20 - 2.73 % 0.29 % Dividend yield 0 % 0 % 0 % As of December 31, 2020 Common Preferred B Preferred C-1 Expected volatility N/A 80 % 80 % Expected term (in years) N/A 2.00 2.00 Risk-free interest rate N/A 0.13 % 0.13 % Dividend yield N/A 0 % 0 % As of December 31, 2019 Common Preferred B Preferred C-1 Expected volatility N/A 80 % 80 % Expected term (in years) N/A 4.00 4.00 Risk-free interest rate N/A 1.66 % 1.66 % Dividend yield N/A 0 % 0 %

Stock-based Compensation Plan (

Stock-based Compensation Plan (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Share-based Payment Arrangement [Abstract]
Summary of Shares Available for Future Grant		Shares Available for Future Grant 2020 2019 Shares Available for future grant 5,993,465 7,855,010
Summary of Stock Option Activity	A summary of options outstanding under the Plan as of September 30, 2021 and changes during the nine months ended September 30, 2021 is presented below: Options Outstanding Number of Weighted Weighted Aggregate Balances as of December 31, 2020 3,891,768 $ 0.44 8.23 $ 4,333 Granted 987,500 $ 2.57 Exercised (1,685,675 ) $ 0.40 Forfeited (400,938 ) $ 0.69 Balances as of September 30, 2021 2,792,655 $ 1.18 8.53 $ 30,331 Options vested and exercisable - September 30, 2021 702,291 $ 0.44 3.37 $ 8,150	A summary of option activity under the Plan as of December 31, 2020 and 2019 and changes during the years ended December 31, 2020 and 2019 is presented below: Options Outstanding Number of Weighted Weighted Aggregate Balances as of December 31, 2018 2,238,598 $ 0.37 8.83 $ 332 Granted 17,500 $ 0.45 Exercised (30,000) $ 0.22 Forfeited (121,875) $ 0.45 Balances as of December 31, 2019 2,104,223 $ 0.37 7.82 $ 821 Granted 2,221,278 $ 0.49 Exercised (74,000) $ 0.09 Forfeited (359,733) $ 0.43 Balances as of December 31, 2020 3,891,768 $ 0.44 8.23 $ 4,333 Options vested and exercisable - December 31, 2019 1,424,380 $ 0.34 7.48 $ 604 Options vested and exercisable - December 31, 2020 1,918,067 $ 0.39 7.21 $ 2,215
Schedule of Share-based Payment Award, Stock Options, Valuation Assumption	In accordance with Accounting Standards Codification (ASC) 718, the fair value of each option grant has been estimated as of the date of grant using the Black-Scholes Merton option-pricing model based on the following weighted average assumptions: Nine Months Ended 2021 2020 Risk-free rate 1.01 % 1.12 % Expected dividends — — Expected term 6 years 6 years Expected volatility 75 % 70 %	In accordance with ASC 718, the fair value of each option grant has been estimated as of the date of grant using the following weighted average assumptions: 2020 2019 Risk-free rate 0.93 % 2.63 % Expected dividends — — Expected term 6 years 6 years Expected volatility 71.06 % 76.77 %
Summary of Stock-based Compensation Expense	The following table presents the amount of stock-based compensation related to stock-based awards to employees on the Company’s Statements of Operations and Other Comprehensive Loss (in thousands): Nine Months Ended 2021 2020 Research and development $ 223 $ 54 Sales and marketing 48 33 General and administrative 349 164 Total stock-based compensation $ 620 $ 251	The following table presents the amount of stock-based compensation related to stock-based awards to employees on the Company’s statements of loss during the years ended December 31, 2020 and 2019 (in thousands): 2020 2019 Research and development $ 79 $ 59 Sales and marketing 47 38 General and administrative 184 78 Total stock-based compensation $ 310 $ 175

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	5 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2020	Sep. 30, 2021	Dec. 31, 2020
Summary Of Assets And Liabilities Measured On Recurring Basis		The Company’s fair value hierarchy for its financial assets and liabilities measured at fair value on a recurring basis are as follows (in thousands): September 30, 2021 Level 1 Level 2 Level 3 Total Assets: Cash equivalents and restricted cash: Money market funds $ 6,986 $ — $ — $ 6,986 Certificate of deposit — 75 — 75 Total Assets $ 6,986 $ 75 $ — $ 7,061 Liabilities: Bridge loan $ — $ — $ 21,432 $ 21,432 Derivative liabilities — — 248,450 248,450 Warrant liabilities — — — — Total Liabilities $ — $ — $ 269,882 $ 269,882 December 31, 2020 Assets: Cash equivalents and restricted cash: Money market funds $ 3,046 $ — $ — $ 3,046 Certificate of deposit — 326 — 326 Total Assets $ 3,046 $ 326 $ — $ 3,372 Liabilities: Bridge loan $ — $ — $ — $ — Derivative liabilities — — 22,911 22,911 Warrant liabilities — — $ 3,329 3,329 Total Liabilities $ — $ — $ 26,240 $ 26,240	The following table presents the Company’s fair value hierarchy for its financial assets and liabilities measured at fair value on a recurring basis (in thousands): December 31, 2020 Level 1 Level 2 Level 3 Total Assets: Cash equivalents and restricted cash: Money market funds $ 3,046 $ — $ — $ 3,046 Certificate of deposit — 326 — 326 Total Assets $ 3,046 $ 326 $ — $ 3,372 Liabilities: Derivative liabilities $ — $ — $ 22,911 $ 22,911 Warrant liabilities — — 3,329 3,329 Total Liabilities $ — $ — $ 26,240 $ 26,240 December 31, 2019 Assets: Restricted cash: Certificate of deposit $ — $ 529 $ — $ 529 Total Assets $ — $ 529 $ — $ 529 December 31, 2020 Level 1 Level 2 Level 3 Total Liabilities: Derivative liabilities $ — $ — $ 11,379 $ 11,379 Warrant liabilities — — 1,989 1,989 Total Liabilities $ — $ — $ 13,368 $ 13,368
Summary Of Changes In The Fair Value Of The Level 3 Liabilities At Fair Value On A Recurring Basis		The following table sets forth a summary of changes in the fair value of the Company’s level 3 liabilities at fair value on a recurring basis (in thousands): Three Months Ended 2021 2020 Bridge loan: Beginning balance June 30 $ — $ — Fair value of Bridge loan funded 20,000 — Accrued PIK and final payment 1,432 — Change in fair value — — Ending balance September 30 21,432 — Warrant liabilities: Beginning balance June 30 22,860 1,979 Change in fair value 2,949 (24 ) Fair value of warrants issued — — Fair value of warrants exercised (25,809 ) — Ending balance September 30 — 1,955 Series C-2 Beginning balance June 30 211,747 7,619 Change in fair value 36,703 (2,089 ) Fair value of derivatives extinguished — — Ending balance September 30 248,450 5,530 Total $ 269,882 $ 7,485 Nine Months Ended 2021 2020 Bridge loan: Beginning balance December 31 $ — $ — Fair value of Bridge loan funded 20,000 — Accrued PIK and final payment 1,432 — Change in fair value — — Ending balance September 30 21,432 — Warrant liabilities: Beginning balance December 31 3,329 1,989 Change in fair value 17,753 (78 ) Fair value of warrants issued 5,096 44 Fair value of warrants exercised (26,178 ) — Ending balance September 30 — 1,955 Series C-2 Beginning balance December 31 22,911 11,379 Change in fair value 248,691 (5,849 ) Fair value of derivatives extinguished (23,152 ) — Ending balance September 30 248,450 5,530 Total $ 269,882 $ 7,485	The following table sets forth a summary of changes in the fair value of the Company’s level 3 liabilities at fair value on a recurring basis for the years ended December 31, 2020 and 2019 (in thousands): 2020 2019 Warrant liabilities: Beginning balance January 1 $ 1,989 $ 1,648 Change in fair value 1,296 341 Fair value of warrants issued 44 — Ending balance December 31 3,329 1,989 2018 Convertible Note Automatic Conversion Rights liability: Beginning balance January 1 — 9 Change in fair value — 19 Fair value of derivatives extinguished upon note conversion — (28 ) Ending balance December 31 — — Series C-2 Convertible Preferred Stock Issuance Right liability: Beginning balance January 1 11,379 — Change in fair value 11,532 — Fair value of derivatives issued — 11,379 Ending balance December 31 22,911 11,379 Total $ 26,240 $ 13,368
Summary of Quantitative Information Regarding Level 3 Fair Value Measurements Inputs at Measurement Dates		The table below shows the valuation assumptions for the warrants immediately prior to the exercises as of and for the nine months ended September 30, 2021: As of and for nine months ended September 30, 2021 Common Series B Series C-1 Series C-2 Expected volatility N/A 80% 80% 80% Expected term (in years) N/A 2 2 2 Risk-free interest rate N/A 0.16% - 0.28% 0.16% - 0.28% 0.16% - 0.28% Dividend yield N/A 0% 0% 0% The warrants were valued using the following assumptions as of December 31, 2020: As of December 31, 2020 Common Series B Series C-1 Series C-2 Expected volatility N/A 80 % 80 % N/A Expected term (in years) N/A 2 2 N/A Risk-free interest rate N/A 0.13 % 0.13 % N/A Dividend yield N/A 0 % 0 % N/A	The warrants were valued using the following assumptions: At issuance date Common Preferred B Preferred C-1 Expected volatility 80 % 80 % 80 % Expected term (in years) 5.00 5.00 3.75 Risk-free interest rate 2.20 % 2.20 - 2.73 % 0.29 % Dividend yield 0 % 0 % 0 % As of December 31, 2020 Common Preferred B Preferred C-1 Expected volatility N/A 80 % 80 % Expected term (in years) N/A 2.00 2.00 Risk-free interest rate N/A 0.13 % 0.13 % Dividend yield N/A 0 % 0 % As of December 31, 2019 Common Preferred B Preferred C-1 Expected volatility N/A 80 % 80 % Expected term (in years) N/A 4.00 4.00 Risk-free interest rate N/A 1.66 % 1.66 % Dividend yield N/A 0 % 0 %
ACON S2 Acquisition Corp [Member]
Summary Of Assets And Liabilities Measured On Recurring Basis	The following table presents information about the Company’s assets that are measured at fair value on a recurring basis as of December 31, 2020 and indicates the fair value hierarchy of the valuation tech niques th Quoted Prices in Significant Other Significant Other Description (Level 1) (Level 2) (Level 3) Assets: Investments held in Trust Account $ 250,004,454 $ — $ — Liabilities: Derivative warrant liabilities – Public Warrants $ 13,625,000 $ — $ — Derivative warrant liabilities – Private Warrants $ — $ — $ 7,729,400	The following table presents information about the Company’s assets and liabilities that are measured at fair value on a recurring basis as of September 30, 2021 and December 31, 2020 and indicates the fair value hierarchy of the valuation techniques that the Company utilized to determine such fair value. September 30, 2021 Quoted Prices in Active Markets Significant Other Observable Inputs Significant Other Unobservable Inputs Description (Level 1) (Level 2) (Level 3) Assets: Investments held in Trust Account $ 250,016,847 $ — $ — Liabilities: Warrant liabilities - Public warrants $ 10,333,330 $ — $ — Warrant liabilities - Private warrants $ — $ — $ 9,883,720 Working capital loan - Related party $ — $ — $ 361,751 December 31, 2020 Quoted Prices in Active Markets Significant Other Observable Inputs Significant Other Unobservable Inputs Description (Level 1) (Level 2) (Level 3) Assets: Investments held in Trust Account $ 250,004,454 $ — $ — Liabilities: Warrant liabilities - Public warrants $ 13,625,000 $ — $ — Warrant liabilities - Private warrants $ — $ — $ 7,729,400
Summary of Quantitative Information Regarding Level 3 Fair Value Measurements Inputs at Measurement Dates	The following table provides quantitative information regarding Level 3 fair value measurements inputs at their measurement dates: As of September 21, 2020 As of September 30, 2020 As of 31, 2020 Stock price $ 9.42 - $9.64 $ 9.42 - $9.64 $ 10.08 Volatility 10.00 % 10.00 % 10.00 % Expected life of the options to convert 6.0 6.0 5.9 Risk-free rate 0.37 % 0.37 % 0.48 % Dividend yield 0.0 % 0.0 % 0.0 % Probability of merger 100.0 % 100.0 % 100.0 %	The following table provides quantitative information regarding Level 3 fair value measurements inputs at their measurement dates: As of September 30, As of December 31 Stock price $ 9.97 $ 10.08 Volatility 42.2 % 10.0 % Expected life of the options to convert 5.02 5.9 Risk-free rate 0.98 % 0.48 % Dividend yield — —
Summary of Change in Level 3 Fair Value of Derivative Warrant Liabilities	The change in the level 3 fair value of the derivative warrant liabilities for the period from July 22, 2020 (inception) through December 31, 2020 Public Warrants Private Warrants Total Derivative warrant liabilities at July 3, 2020 (inception) $ — $ — $ — Issuance of Warrants 12,500,000 7,000,000 19,500,000 Change in fair value of derivative warrant liabilities 1,125,000 729,400 1,854,400 Transfer of Public Warrants to level 1 (13,625,000 ) — (13,625,000 ) Derivative warrant liabilities at December 31, 2020 $ — $ 7,729,400 $ 7,729,400	The change in the fair value of the Level 3 derivative warrant liabilities for the nine months ended September 30, 2021 is summarized as follows: Derivative warrant liabilities at December 31, 2020 $ 7,729,400 Change in fair value of derivative warrant liabilities 2,154,320 Derivative warrant liabilities at September 30, 2021 $ 9,883,720
ACON S2 Acquisition Corp [Member] | Working Capital Loan Related Party [Member]
Summary of Change in Level 3 Fair Value of Derivative Warrant Liabilities		The change in the fair value of the working capital loan – related party measured with Level 3 inputs for the nine months ended September 30, 2021 is summarized as follows: Fair value of working capital loan - related party at December 31, 2020 $ — Initial fair value of working capital loan - related party 361,751 Change in fair value of working capital loan - related party — Fair value of working capital loan - related party, September 30, 2020 $ 361,751

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Summary of Net Deferred Tax Assets	The significant components of deferred tax assets and liabilities are as follows (in thousands): As of December 31, 2020 2019 Deferred Tax Assets: Net operating losses $ 11,566 $ 7,365 Tax credit carryforward 47 12 Other 837 513 Deferred tax assets 12,450 7,890 Valuation allowance (12,450 ) (7,890 ) Deferred tax assets, net of valuation allowance $ — $ —
Summary Of Reconciliation of U.S. Federal Statutory Income Tax Rate and Effective Income Tax Rate	The effective tax rate of the Company’s provision for income taxes differs from the federal statutory rate as follows: Years Ended December 31, 2020 2019 Tax computed at federal statutory rate 21.0 % 21.0 % State tax, net of federal tax benefit 3.0 4.4 Stock compensation (0.2 ) (0.2 ) Permanent differences (8.9 ) (2.3 ) 163(I) Interest — (0.9 ) R&D tax credits 0.1 0.1 Other — (0.1 ) Valuation allowance (15.0 ) (22.0 ) Income tax expense (benefit) 0.0 % 0.0 %
Summary of Company's uncertain tax positions	The changes in the Company’s uncertain tax positions are summarized as follows (in thousands): Balance as of December 31, 2018 $ — Additions in 2019 12 Balance as of December 31, 2019 12 Additions in 2020 35 Balance as of December 31, 2020 $ 47

Description of Business and S_3

Description of Business and Summary of Significant Accounting Policies - Additional Information (Detail) $ / shares in Units, $ in Thousands	Oct. 08, 2021USD ($)$ / sharesshares	Sep. 30, 2021USD ($)$ / shares	Sep. 30, 2021USD ($)$ / sharesshares	Sep. 30, 2020USD ($)	Dec. 31, 2020USD ($)Segmentshares	Dec. 31, 2019USD ($)shares
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Comprehensive income loss					$ 0	$ 0
Cash and cash equivalents at carrying value		$ 8,019	$ 8,019	$ 9,286	$ 4,901	18,290
Number of reportable segment | Segment					1
Research and development arrangement with federal government, customer funding to offset costs incurred					$ 40	20
Grants receivable					0	0
Impairment of long lived assets to be disposed of					0	0
Revenue from contract with customer, excluding assessed tax					0	0
Advertising costs					8	$ 9
Dividends					$ 0
Share based compensation arrangement by share based payment award, Fair value assumptions, expected dividend rate			0.00%	0.00%	0.00%	0.00%
Unrecognized tax benefits, income tax penalties and interest accrued					$ 0	$ 0
Stock issue price | $ / shares		$ 10	$ 10
Stock options exercised ,Shares | shares			1,685,675		74,000	30,000
Stock options exercised ,Value		$ 10	$ 664	$ 6	$ 7	$ 6
Merger Agreement [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Payments for Merger Related Costs			246,000
Merger Agreement [Member] | STWO Stockholders [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Issuance of ordinary shares to Sponsor			$ 250,000
Stock options exercised ,Shares | shares			20,754,719
Stock options exercised ,Value			$ 207,500
ACON S2 Acquisition Corp [Member] | Merger Agreement [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Business Acquisition, Transaction Costs	$ 3,471
PIPE Investors [Member] | STWO Stockholders [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Issuance of ordinary shares to Sponsor	$ 250,000
Stock issued during period, shares, new issues | shares	25,000,000
Stock issue price | $ / shares	$ 10
Maximum [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Property, plant and equipment, useful life					7 years
Minimum [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Property, plant and equipment, useful life					3 years
Accrued Liabilities And Other Current Liabilities [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Research and development arrangement with federal government customer funding repayable current					$ 186	$ 0

Description of Organization, _2

Description of Organization, Business Operations and Basis of Presentation - Additional Information (Details)	Oct. 08, 2021USD ($)shares	Sep. 21, 2020USD ($)$ / sharesshares	Sep. 30, 2020USD ($)$ / shares	Sep. 30, 2021USD ($)$ / sharesshares	Dec. 31, 2020USD ($)$ / sharesshares	Sep. 30, 2021USD ($)$ / sharesshares	Sep. 30, 2020USD ($)$ / shares	Dec. 31, 2020USD ($)$ / sharesshares	Dec. 31, 2019USD ($)$ / sharesshares	May 07, 2021$ / shares	May 06, 2021$ / shares	Jul. 27, 2020USD ($)
Description Of Organization Business Operations And Basis Of Presentation [Line Items]
Deferred underwriting commissions		$ 8,800,000
Stock issue price | $ / shares				$ 10		$ 10
Proceeds received from private placement		7,000,000
Common stock, par or stated value per share | $ / shares				$ 0.0001	$ 0.0001	$ 0.0001		$ 0.0001	$ 0.0001	$ 0.0001
Common Stock, Shares, Issued | shares				9,125,954	7,134,668	9,125,954		7,134,668	7,060,668
Stock issued during the period shares Stock Options Exercised | shares | shares						1,685,675		74,000	30,000
Class of Warrant or Right, Outstanding | shares				0	1,738,382	0		1,738,382	1,668,382
Stock Issued During Period, Value, Stock Options Exercised				$ 10,000		$ 664,000	$ 6,000	$ 7,000	$ 6,000
ACON S2 Acquisition Corp [Member]
Description Of Organization Business Operations And Basis Of Presentation [Line Items]
Issuance of ordinary shares to Sponsor			$ 25,000		$ 25,000
Proceeds received from initial public offering, gross			250,000,000		250,000,000
Offering costs			5,140,200		5,466,700
Proceeds received from private placement		7,000,000	$ 7,000,000		$ 7,000,000
Net proceeds from issuance of initial public offering and private placement		$ 250,000,000
Net proceeds from issuance of initial public offering and private placement, price per share | $ / shares		$ 10
Assets with fair market value equal					80.00%	80.00%
Temporary equity, redemption price per share | $ / shares				$ 10	$ 10	$ 10		$ 10
Maximum net tangible assets for business combination				$ 5,000,001	$ 5,000,001	$ 5,000,001		$ 5,000,001
Percentage of public shares to redeemed				100.00%	100.00%	100.00%		100.00%
Interest to pay dissolution expenses					$ 100,000	$ 100,000
Operating bank accounts				$ 1,000	470,000	1,000		$ 470,000
Working capital				1,900,000	547,000	1,900,000		547,000
Note payable - related party				$ 361,751		$ 361,751
CommonStockExchangeRatio	1.47110014425
CashPaymentsToStockholdersInLieuOfFractionalShares	$ 311.03
Stock issued during the period shares Stock Options Exercised | shares | shares	20,754,719
Class of Warrant or Right, Outstanding | shares				13,000,000		13,000,000
Stock Issued During Period, Value, Stock Options Exercised	$ 207,547,190
ACON S2 Acquisition Corp [Member] | P I P E Investors
Description Of Organization Business Operations And Basis Of Presentation [Line Items]
Issuance of ordinary shares to Sponsor						$ 250,000,000
Stock issue price | $ / shares				$ 10		$ 10
Stock issued during period, shares, new issues | shares						25,000,000
ACON S2 Acquisition Corp [Member] | Target Entity [Member]
Description Of Organization Business Operations And Basis Of Presentation [Line Items]
Business combination post transaction company acquires				50.00%	50.00%	50.00%		50.00%
ACON S2 Acquisition Corp [Member] | Sponsor | Working Capital Loans
Description Of Organization Business Operations And Basis Of Presentation [Line Items]
Borrowing outstanding		$ 0		$ 362,000	$ 0	$ 362,000		$ 0				$ 0
ACON S2 Acquisition Corp [Member] | Class A ordinary shares
Description Of Organization Business Operations And Basis Of Presentation [Line Items]
Proceeds received from initial public offering, gross					250,000,000	250,000,000
Offering costs					$ 13,646,752	$ 13,646,752
Temporary equity, redemption price per share | $ / shares				$ 10	$ 10	$ 10		$ 10
Percentage of public shares to redeemed				15.00%	15.00%	15.00%		15.00%
Common stock, par or stated value per share | $ / shares		$ 0.0001	$ 0.0001	$ 0.0001	$ 0.0001	$ 0.0001	$ 0.0001	$ 0.0001
ACON S2 Acquisition Corp [Member] | ESS Common Stock
Description Of Organization Business Operations And Basis Of Presentation [Line Items]
Common stock, par or stated value per share | $ / shares											$ 0.0001
Common Stock, Shares, Issued | shares	99,562,793
ACON S2 Acquisition Corp [Member] | Common Stock
Description Of Organization Business Operations And Basis Of Presentation [Line Items]
Common stock, par or stated value per share | $ / shares											$ 0.0001
ACON S2 Acquisition Corp [Member] | LegacyEssMember [Member]
Description Of Organization Business Operations And Basis Of Presentation [Line Items]
Common Stock, Shares, Issued | shares	15,675,002
ACON S2 Acquisition Corp [Member] | Initial Public Offering
Description Of Organization Business Operations And Basis Of Presentation [Line Items]
Issuance of ordinary shares to Sponsor		$ 25,000,000
Units issued, price per unit | $ / shares		$ 10
Proceeds received from initial public offering, gross		$ 250,000,000
Offering costs		14,400,000
Deferred underwriting commissions		$ 8,800,000
Stock issue price | $ / shares				$ 10	$ 10	$ 10		$ 10
Stock issued during period, shares, new issues | shares		25,000,000
ACON S2 Acquisition Corp [Member] | Initial Public Offering | Sponsor | Promissory Note
Description Of Organization Business Operations And Basis Of Presentation [Line Items]
Issuance of ordinary shares to Sponsor		$ 25,000
Note payable - related party		112,000										$ 112,000
ACON S2 Acquisition Corp [Member] | Over-Allotment Option
Description Of Organization Business Operations And Basis Of Presentation [Line Items]
Issuance of ordinary shares to Sponsor		$ 3,750,000
Units issued, price per unit | $ / shares		$ 10
ACON S2 Acquisition Corp [Member] | Private Placement
Description Of Organization Business Operations And Basis Of Presentation [Line Items]
Issuance of ordinary shares to Sponsor		$ 4,666,667
Units issued, price per unit | $ / shares		$ 1.50
Number of shares forfeited during the period | shares | shares	583,333
Class of Warrant or Right, Outstanding | shares	4,083,334
ACON S2 Acquisition Corp [Member] | Private Placement | Share-based Payment Arrangement, Tranche One [Member]
Description Of Organization Business Operations And Basis Of Presentation [Line Items]
Number of shares vested during the period | shares	3,500,000
ACON S2 Acquisition Corp [Member] | Private Placement | Share-based Payment Arrangement, Tranche Two [Member]
Description Of Organization Business Operations And Basis Of Presentation [Line Items]
Number of shares vested during the period | shares	583,334

Restatement of Financial Stat_3

Restatement of Financial Statements - Effect of Financial Statement Adjustments Related to Restatement on Balance Sheet (Details) - USD ($)	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Sep. 21, 2020	Jul. 20, 2020	Jun. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total assets	$ 17,824,000			$ 9,023,000					$ 21,140,000
Liabilities and Equity [Abstract]
Total current liabilities	31,047,000			8,394,000					2,888,000
Total liabilities	285,412,000			36,911,000					18,926,000
Class A ordinary share, $0.0001 par value; shares subject to possible redemption				215,583,980
Ordinary shares	1,000			1,000					1,000
Additional paid-in capital	2,516,000			1,079,000					762,000
Accumulated deficit	(360,178,000)			(63,493,000)					(33,074,000)
Total shareholders' equity	(357,661,000)	$ (306,606,000)		(62,260,000)	$ (38,101,000)			$ (35,407,000)	(32,158,000)	$ (20,793,000)
Total Liabilities and Shareholders' Equity	17,824,000			9,023,000					$ 21,140,000
ACON S2 Acquisition Corp [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total assets	250,218,951			250,827,490	252,167,049	$ 252,174,258
Liabilities and Equity [Abstract]
Total current liabilities	2,143,379			139,107	816,145
Deferred underwriting commissions	8,750,000			8,750,000	8,750,000
Derivative warrant liabilities	20,217,050			21,354,400
Total liabilities	31,110,429			30,243,507	29,066,145	29,049,500
Class A ordinary share, $0.0001 par value; shares subject to possible redemption				250,000,000	250,000,000	250,000,000
Preference shares—$0.0001 par value					0
Additional paid-in capital	94			94
Accumulated deficit				(29,416,642)	(26,899,815)	(26,875,961)
Total shareholders' equity	(30,891,478)	(26,961,660)	$ (20,177,054)	(29,416,017)	(26,899,096)	(26,875,242)
Total Liabilities and Shareholders' Equity	250,218,951			250,827,490	252,167,049	252,174,258
ACON S2 Acquisition Corp [Member] | Amendment One [Member]
Liabilities and Equity [Abstract]
Total liabilities				30,243,507	29,066,145
Additional paid-in capital				8,293,299	5,776,310
Accumulated deficit				(3,294,265)	(777,344)
Total shareholders' equity				5,000,003	5,000,004
Previously Reported [Member] | ACON S2 Acquisition Corp [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total assets		250,304,732	250,663,379	250,827,490	252,167,049	252,174,258
Liabilities and Equity [Abstract]
Total current liabilities				139,107	816,145
Deferred underwriting commissions				8,750,000	8,750,000
Derivative warrant liabilities				0
Total liabilities		27,266,392	20,840,433	30,243,507	29,066,145	29,049,500
Class A ordinary share, $0.0001 par value; shares subject to possible redemption		218,038,330	224,822,940	215,583,980	218,100,900	218,124,750
Preference shares—$0.0001 par value		0	0	0	0	0
Additional paid-in capital		6,784,542	0	8,293,299	5,776,310	5,747,460
Accumulated deficit		(1,785,477)	4,999,129	(3,294,265)	(777,344)	(748,490)
Total shareholders' equity		5,000,010	5,000,006	5,000,003	5,000,004	5,000,008
Total Liabilities and Shareholders' Equity		250,304,732	250,663,379	250,827,490	252,167,049	252,174,258
Previously Reported [Member] | ACON S2 Acquisition Corp [Member] | Amendment One [Member]
Liabilities and Equity [Abstract]
Total liabilities				8,889,107	9,566,145
Additional paid-in capital				5,703,622	5,041,015
Accumulated deficit				(704,375)	(41,854)
Total shareholders' equity				5,000,003	5,000,004
Revision of Prior Period, Adjustment [Member] | ACON S2 Acquisition Corp [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total assets				0
Liabilities and Equity [Abstract]
Total current liabilities				0
Deferred underwriting commissions				0	0
Derivative warrant liabilities				21,354,400
Class A ordinary share, $0.0001 par value; shares subject to possible redemption		31,961,670	25,177,060	34,416,020	31,899,100	31,875,250
Preference shares—$0.0001 par value		0	0	0	0	0
Additional paid-in capital		(6,784,542)	0	(8,293,299)	(5,776,310)	(5,747,460)
Accumulated deficit		(25,176,808)	(25,176,808)	(26,122,377)	(26,122,471)	(26,127,471)
Total shareholders' equity		(31,961,670)	(25,177,060)	(34,416,020)	(31,899,100)	(31,875,250)
Total Liabilities and Shareholders' Equity		0	0	0	0	0
Revision of Prior Period, Adjustment [Member] | ACON S2 Acquisition Corp [Member] | Amendment One [Member]
Liabilities and Equity [Abstract]
Total liabilities				21,354,400	19,500,000
Additional paid-in capital				2,589,677	735,295
Accumulated deficit				(2,589,890)	(735,490)
Total shareholders' equity				0
Common Class A [Member] | ACON S2 Acquisition Corp [Member]
Liabilities and Equity [Abstract]
Class A ordinary share, $0.0001 par value; shares subject to possible redemption	250,000,000			250,000,000	218,100,900
Ordinary shares
Common Class A [Member] | ACON S2 Acquisition Corp [Member] | Amendment One [Member]
Liabilities and Equity [Abstract]
Ordinary shares				344	319
Common Class A [Member] | Previously Reported [Member] | ACON S2 Acquisition Corp [Member]
Liabilities and Equity [Abstract]
Class A ordinary share, $0.0001 par value; shares subject to possible redemption				236,938,380	237,600,900
Ordinary shares		320	252	344	319	319
Common Class A [Member] | Previously Reported [Member] | ACON S2 Acquisition Corp [Member] | Amendment One [Member]
Liabilities and Equity [Abstract]
Ordinary shares				131	124
Common Class A [Member] | Revision of Prior Period, Adjustment [Member] | ACON S2 Acquisition Corp [Member]
Liabilities and Equity [Abstract]
Class A ordinary share, $0.0001 par value; shares subject to possible redemption				(21,354,400)	(19,500,000)
Ordinary shares		(320)	(252)	(344)	(319)	(319)
Common Class A [Member] | Revision of Prior Period, Adjustment [Member] | ACON S2 Acquisition Corp [Member] | Amendment One [Member]
Liabilities and Equity [Abstract]
Ordinary shares				213	195
Common Class B [Member] | ACON S2 Acquisition Corp [Member]
Liabilities and Equity [Abstract]
Ordinary shares	625			625	719	719
Total shareholders' equity	$ 625	625	625	625	719
Common Class B [Member] | Previously Reported [Member] | ACON S2 Acquisition Corp [Member]
Liabilities and Equity [Abstract]
Ordinary shares		625	625	625	719	719
Common Class B [Member] | Revision of Prior Period, Adjustment [Member] | ACON S2 Acquisition Corp [Member]
Liabilities and Equity [Abstract]
Ordinary shares		$ 0	$ 0	$ 0	$ 0	$ 0

Restatement of Financial Stat_4

Restatement of Financial Statements - Effect of Financial Statement Adjustments Related to Restatement on Balance Sheet (Parenthetical) (Details) - $ / shares	Sep. 30, 2021	May 07, 2021	Dec. 31, 2020	Sep. 30, 2020	Sep. 21, 2020	Dec. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Preferred shares, par value		$ 0.0001
Ordinary shares, par value	$ 0.0001	$ 0.0001	$ 0.0001			$ 0.0001
ACON S2 Acquisition Corp [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Preferred shares, par value	0.0001		0.0001	$ 0.0001
Temporary equity, par value			0.0001	0.0001
Common Class A [Member] | ACON S2 Acquisition Corp [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Temporary equity, par value				0.0001
Ordinary shares, par value	0.0001		0.0001	0.0001	$ 0.0001
Common Class B [Member] | ACON S2 Acquisition Corp [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Ordinary shares, par value	$ 0.0001		$ 0.0001	$ 0.0001

Restatement of Financial Stat_5

Restatement of Financial Statements - Effect of Financial Statement Adjustments Related to Restatement on Statement of Operations (Details) - USD ($)	Sep. 21, 2020	Sep. 30, 2020	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Dec. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loss from operations			$ (11,036,000)			$ (4,844,000)		$ (29,474,000)	$ (11,957,000)	$ (17,392,000)	$ (9,889,000)
Other Nonoperating Income (Expense) [Abstract]
Change in fair value of derivative warrant liabilities			(2,949,000)			24,000		(17,753,000)	78,000	(1,296,000)	(341,000)
Total other (expense) income			(40,289,000)			2,073,000		(267,211,000)	5,757,000	(13,027,000)	(1,578,000)
Net loss			$ (51,325,000)			$ (2,771,000)		$ (296,685,000)	$ (6,200,000)	$ (30,419,000)	$ (11,467,000)
Basic and diluted weighted average shares outstanding			8,823,458			7,102,536		8,458,054	7,099,532	7,108,389	7,043,575
Basic and diluted net income (loss) per share			$ (5.82)			$ (0.39)		$ (35.08)	$ (0.87)	$ (4.28)	$ (1.64)
ACON S2 Acquisition Corp [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loss from operations		$ (41,854)	$ (1,702,053)				$ (708,829)	$ (2,625,204)
Other Nonoperating Income (Expense) [Abstract]
Change in fair value of derivative warrant liabilities	$ (19,500,000)		(2,232,690)				(1,854,400)	1,137,350
Financing costs—derivative warrant liabilities		(735,490)					(735,490)
Gain on marketable securities (net), and dividends held in Trust Account			4,925				4,454	12,393
Total other (expense) income		(735,490)	(2,227,765)				(2,585,436)	1,149,743
Net loss		(777,344)	$ (3,929,818)	$ (6,784,606)	$ 9,238,963		(3,294,265)	$ (1,475,461)
Earnings (loss) allocable to ordinary shares subject to possible redemption		(293,337)					(2,374,665)
Loss allocable to non-redeemable ordinary shares		(484,007)					(919,600)
Previously Reported [Member] | ACON S2 Acquisition Corp [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loss from operations		(41,854)					(708,829)
Other Nonoperating Income (Expense) [Abstract]
Change in fair value of derivative warrant liabilities							0
Financing costs—derivative warrant liabilities							0
Gain on marketable securities (net), and dividends held in Trust Account							4,454
Total other (expense) income							4,454
Net loss		(41,854)					(704,375)
Earnings (loss) allocable to ordinary shares subject to possible redemption		0					3,841
Loss allocable to non-redeemable ordinary shares		(777,344)					(3,298,105)
Revision of Prior Period, Adjustment [Member] | ACON S2 Acquisition Corp [Member]
Other Nonoperating Income (Expense) [Abstract]
Change in fair value of derivative warrant liabilities							(1,854,400)
Financing costs—derivative warrant liabilities		(735,490)					(735,490)
Total other (expense) income							(2,589,890)
Net loss		(735,490)					(2,589,890)
Earnings (loss) allocable to ordinary shares subject to possible redemption		(293,337)					(2,378,506)
Loss allocable to non-redeemable ordinary shares		$ 293,337					$ 2,378,505
Common Class A [Member] | ACON S2 Acquisition Corp [Member]
Other Nonoperating Income (Expense) [Abstract]
Basic and diluted weighted average shares outstanding		3,787,879	25,000,000				16,139,241	25,000,000
Basic and diluted net income (loss) per share		$ (0.08)	$ (0.13)				$ (0.15)	$ (0.05)
Common Class A [Member] | ACON S2 Acquisition Corp [Member] | Amendment One [Member]
Other Nonoperating Income (Expense) [Abstract]
Basic and diluted weighted average shares outstanding							21,719,426
Common Class A [Member] | Previously Reported [Member] | ACON S2 Acquisition Corp [Member]
Other Nonoperating Income (Expense) [Abstract]
Basic and diluted weighted average shares outstanding		21,810,415					21,719,416
Basic and diluted net income (loss) per share		$ 0					$ 0
Common Class A [Member] | Previously Reported [Member] | ACON S2 Acquisition Corp [Member] | Amendment One [Member]
Other Nonoperating Income (Expense) [Abstract]
Basic and diluted weighted average shares outstanding							23,734,800
Common Class A [Member] | Revision of Prior Period, Adjustment [Member] | ACON S2 Acquisition Corp [Member]
Other Nonoperating Income (Expense) [Abstract]
Basic and diluted weighted average shares outstanding		(18,022,536)					(5,580,185)
Basic and diluted net income (loss) per share		$ (0.08)					$ (0.15)
Common Class B [Member] | ACON S2 Acquisition Corp [Member]
Other Nonoperating Income (Expense) [Abstract]
Basic and diluted weighted average shares outstanding		6,250,000	6,250,000				6,250,000	6,250,000
Basic and diluted net income (loss) per share		$ (0.08)	$ (0.13)				$ (0.15)	$ (0.05)
Common Class B [Member] | ACON S2 Acquisition Corp [Member] | Amendment One [Member]
Other Nonoperating Income (Expense) [Abstract]
Basic and diluted weighted average shares outstanding							8,310,766
Basic and diluted net income (loss) per share							$ (0.40)
Common Class B [Member] | Previously Reported [Member] | ACON S2 Acquisition Corp [Member]
Other Nonoperating Income (Expense) [Abstract]
Basic and diluted weighted average shares outstanding		6,732,994					8,310,766
Basic and diluted net income (loss) per share		$ (0.12)					$ (0.40)
Common Class B [Member] | Previously Reported [Member] | ACON S2 Acquisition Corp [Member] | Amendment One [Member]
Other Nonoperating Income (Expense) [Abstract]
Basic and diluted weighted average shares outstanding							7,052,256
Basic and diluted net income (loss) per share							$ (0.10)
Common Class B [Member] | Revision of Prior Period, Adjustment [Member] | ACON S2 Acquisition Corp [Member]
Other Nonoperating Income (Expense) [Abstract]
Basic and diluted weighted average shares outstanding		(482,994)					(2,060,766)
Basic and diluted net income (loss) per share		$ 0.04					$ 0.25

Restatement of Financial Stat_6

Restatement of Financial Statements - Effect of Financial Statement Adjustments Related to Restatement on Statement of Cash Flows (Details) - USD ($)	2 Months Ended	3 Months Ended				5 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Dec. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net loss		$ (51,325,000)			$ (2,771,000)		$ (296,685,000)	$ (6,200,000)	$ (30,419,000)	$ (11,467,000)
Net cash used in operating activities							(28,343,000)	(12,109,000)	(16,645,000)	(6,675,000)
Net cash used in investing activities							(288,000)	(464,000)	(502,000)	(851,000)
Net cash provided by financing activities							31,548,000	4,792,000	4,722,000	22,254,000
Net change in cash							2,917,000	$ (7,781,000)	$ (12,425,000)	$ 14,728,000
ACON S2 Acquisition Corp [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net loss	$ (777,344)	$ (3,929,818)	$ (6,784,606)	$ 9,238,963		$ (3,294,265)	(1,475,461)
Adjustments to reconcile net loss to net cash used in operating activities	751,490					2,601,436
Net cash used in operating activities	(26,800)					(976,685)	(468,896)
Net cash used in investing activities	(250,000,000)					(250,000,000)
Net cash provided by financing activities	251,773,258					251,446,758
Net change in cash	1,746,458					470,073	$ (468,896)
Previously Reported [Member] | ACON S2 Acquisition Corp [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net loss	(41,854)					(704,375)
Adjustments to reconcile net loss to net cash used in operating activities	16,000					11,546
Net cash used in operating activities	(26,800)					(976,685)
Net cash used in investing activities	(250,000,000)					(250,000,000)
Net cash provided by financing activities	251,773,258					251,446,758
Net change in cash	1,746,458					470,073
Revision of Prior Period, Adjustment [Member] | ACON S2 Acquisition Corp [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net loss	(735,490)					(2,589,890)
Adjustments to reconcile net loss to net cash used in operating activities	$ 735,490					$ 2,589,890

Restatement of Financial Stat_7

Restatement of Financial Statements - Schedule of Unaudited Quarterly Financial Information for Restatement and Revision of Unaudited Condensed Balance Sheet (Details) - USD ($)	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Sep. 21, 2020	Jul. 20, 2020	Jun. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total assets	$ 17,824,000			$ 9,023,000					$ 21,140,000
Liabilities and Equity [Abstract]
Total current liabilities	31,047,000			8,394,000					2,888,000
Derivative warrant liabilities	248,450,000			22,911,000					11,379,000
Total liabilities	285,412,000			36,911,000					18,926,000
Class A ordinary share, $0.0001 par value; shares subject to possible redemption				215,583,980
Stockholders' Equity Attributable to Parent [Abstract]
Ordinary shares	1,000			1,000					1,000
Additional paid-in capital	2,516,000			1,079,000					762,000
Accumulated deficit	(360,178,000)			(63,493,000)					(33,074,000)
Total shareholders' equity	(357,661,000)	$ (306,606,000)		(62,260,000)	$ (38,101,000)			$ (35,407,000)	(32,158,000)	$ (20,793,000)
Total liabilities and shareholders' equity	17,824,000			9,023,000					$ 21,140,000
ACON S2 Acquisition Corp [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total assets	250,218,951			250,827,490	252,167,049	$ 252,174,258
Liabilities and Equity [Abstract]
Total current liabilities	2,143,379			139,107	816,145
Deferred underwriting commissions	8,750,000			8,750,000	8,750,000
Derivative warrant liabilities					19,500,000
Total liabilities	31,110,429			30,243,507	29,066,145	29,049,500
Class A ordinary share, $0.0001 par value; shares subject to possible redemption				250,000,000	250,000,000	250,000,000
Stockholders' Equity Attributable to Parent [Abstract]
Preference shares—$0.0001 par value					0
Additional paid-in capital	94			94
Accumulated deficit				(29,416,642)	(26,899,815)	(26,875,961)
Total shareholders' equity	(30,891,478)	(26,961,660)	$ (20,177,054)	(29,416,017)	(26,899,096)	(26,875,242)
Total liabilities and shareholders' equity	250,218,951			250,827,490	252,167,049	252,174,258
ACON S2 Acquisition Corp [Member] | Amendment One [Member]
Liabilities and Equity [Abstract]
Total liabilities				30,243,507	29,066,145
Stockholders' Equity Attributable to Parent [Abstract]
Additional paid-in capital				8,293,299	5,776,310
Accumulated deficit				(3,294,265)	(777,344)
Total shareholders' equity				5,000,003	5,000,004
Common Class A [Member] | ACON S2 Acquisition Corp [Member]
Liabilities and Equity [Abstract]
Class A ordinary share, $0.0001 par value; shares subject to possible redemption	250,000,000			250,000,000	218,100,900
Stockholders' Equity Attributable to Parent [Abstract]
Ordinary shares
Common Class A [Member] | ACON S2 Acquisition Corp [Member] | Amendment One [Member]
Stockholders' Equity Attributable to Parent [Abstract]
Ordinary shares				344	319
Common Class B [Member] | ACON S2 Acquisition Corp [Member]
Stockholders' Equity Attributable to Parent [Abstract]
Ordinary shares	625			625	719	719
Total shareholders' equity	$ 625	625	625	625	719
Previously Reported [Member] | ACON S2 Acquisition Corp [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total assets		250,304,732	250,663,379	250,827,490	252,167,049	252,174,258
Liabilities and Equity [Abstract]
Total current liabilities				139,107	816,145
Deferred underwriting commissions				8,750,000	8,750,000
Total liabilities		27,266,392	20,840,433	30,243,507	29,066,145	29,049,500
Class A ordinary share, $0.0001 par value; shares subject to possible redemption		218,038,330	224,822,940	215,583,980	218,100,900	218,124,750
Stockholders' Equity Attributable to Parent [Abstract]
Preference shares—$0.0001 par value		0	0	0	0	0
Additional paid-in capital		6,784,542	0	8,293,299	5,776,310	5,747,460
Accumulated deficit		(1,785,477)	4,999,129	(3,294,265)	(777,344)	(748,490)
Total shareholders' equity		5,000,010	5,000,006	5,000,003	5,000,004	5,000,008
Total liabilities and shareholders' equity		250,304,732	250,663,379	250,827,490	252,167,049	252,174,258
Previously Reported [Member] | ACON S2 Acquisition Corp [Member] | Amendment One [Member]
Liabilities and Equity [Abstract]
Total liabilities				8,889,107	9,566,145
Stockholders' Equity Attributable to Parent [Abstract]
Additional paid-in capital				5,703,622	5,041,015
Accumulated deficit				(704,375)	(41,854)
Total shareholders' equity				5,000,003	5,000,004
Previously Reported [Member] | Common Class A [Member] | ACON S2 Acquisition Corp [Member]
Liabilities and Equity [Abstract]
Class A ordinary share, $0.0001 par value; shares subject to possible redemption				236,938,380	237,600,900
Stockholders' Equity Attributable to Parent [Abstract]
Ordinary shares		320	252	344	319	319
Previously Reported [Member] | Common Class A [Member] | ACON S2 Acquisition Corp [Member] | Amendment One [Member]
Stockholders' Equity Attributable to Parent [Abstract]
Ordinary shares				131	124
Previously Reported [Member] | Common Class B [Member] | ACON S2 Acquisition Corp [Member]
Stockholders' Equity Attributable to Parent [Abstract]
Ordinary shares		625	625	625	719	719
Revision of Prior Period, Adjustment [Member] | ACON S2 Acquisition Corp [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total assets				0
Liabilities and Equity [Abstract]
Total current liabilities				0
Deferred underwriting commissions				0	0
Derivative warrant liabilities					19,500,000
Class A ordinary share, $0.0001 par value; shares subject to possible redemption		31,961,670	25,177,060	34,416,020	31,899,100	31,875,250
Stockholders' Equity Attributable to Parent [Abstract]
Preference shares—$0.0001 par value		0	0	0	0	0
Additional paid-in capital		(6,784,542)	0	(8,293,299)	(5,776,310)	(5,747,460)
Accumulated deficit		(25,176,808)	(25,176,808)	(26,122,377)	(26,122,471)	(26,127,471)
Total shareholders' equity		(31,961,670)	(25,177,060)	(34,416,020)	(31,899,100)	(31,875,250)
Total liabilities and shareholders' equity		0	0	0	0	0
Revision of Prior Period, Adjustment [Member] | ACON S2 Acquisition Corp [Member] | Amendment One [Member]
Liabilities and Equity [Abstract]
Total liabilities				21,354,400	19,500,000
Stockholders' Equity Attributable to Parent [Abstract]
Additional paid-in capital				2,589,677	735,295
Accumulated deficit				(2,589,890)	(735,490)
Total shareholders' equity				0
Revision of Prior Period, Adjustment [Member] | Common Class A [Member] | ACON S2 Acquisition Corp [Member]
Liabilities and Equity [Abstract]
Class A ordinary share, $0.0001 par value; shares subject to possible redemption				(21,354,400)	(19,500,000)
Stockholders' Equity Attributable to Parent [Abstract]
Ordinary shares		(320)	(252)	(344)	(319)	(319)
Revision of Prior Period, Adjustment [Member] | Common Class A [Member] | ACON S2 Acquisition Corp [Member] | Amendment One [Member]
Stockholders' Equity Attributable to Parent [Abstract]
Ordinary shares				213	195
Revision of Prior Period, Adjustment [Member] | Common Class B [Member] | ACON S2 Acquisition Corp [Member]
Stockholders' Equity Attributable to Parent [Abstract]
Ordinary shares		$ 0	$ 0	$ 0	$ 0	$ 0

Restatement of Financial Stat_8

Restatement of Financial Statements - Schedule of Unaudited Quarterly Financial Information for Restatement and Revision of Unaudited Condensed Balance Sheet (Parenthetical) (Details) - $ / shares	Sep. 30, 2021	May 07, 2021	Dec. 31, 2020	Sep. 30, 2020	Sep. 21, 2020	Dec. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Preferred Stock, Par or Stated Value Per Share		$ 0.0001
Common Stock, Par or Stated Value Per Share	$ 0.0001	$ 0.0001	$ 0.0001			$ 0.0001
ACON S2 Acquisition Corp [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Temporary Equity, Par or Stated Value Per Share			0.0001	$ 0.0001
Preferred Stock, Par or Stated Value Per Share	0.0001		0.0001	0.0001
Common Class A [Member] | ACON S2 Acquisition Corp [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Temporary Equity, Par or Stated Value Per Share				0.0001
Common Stock, Par or Stated Value Per Share	0.0001		0.0001	0.0001	$ 0.0001
Common Class B [Member] | ACON S2 Acquisition Corp [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Common Stock, Par or Stated Value Per Share	$ 0.0001		$ 0.0001	$ 0.0001

Restatement of Financial Stat_9

Restatement of Financial Statements - Schedule of Unaudited Quarterly Financial Information for Restatement and Revision of Unaudited Condensed Statement of Operations (Details) - USD ($)	2 Months Ended	3 Months Ended				5 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Dec. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loss from operations		$ (11,036,000)			$ (4,844,000)		$ (29,474,000)	$ (11,957,000)	$ (17,392,000)	$ (9,889,000)
Other Nonoperating Income (Expense) [Abstract]
Total other (expense) income		945,000			(2,000)		926,000	(64,000)	(67,000)	(199,000)
Net loss		$ (51,325,000)			$ (2,771,000)		$ (296,685,000)	$ (6,200,000)	$ (30,419,000)	$ (11,467,000)
Basic and diluted weighted average shares outstanding		8,823,458			7,102,536		8,458,054	7,099,532	7,108,389	7,043,575
Basic and diluted net income per share		$ (5.82)			$ (0.39)		$ (35.08)	$ (0.87)	$ (4.28)	$ (1.64)
ACON S2 Acquisition Corp [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loss from operations	$ (41,854)	$ (1,702,053)				$ (708,829)	$ (2,625,204)
Other Nonoperating Income (Expense) [Abstract]
Financing costs—derivative warrant liabilities	(735,490)					(735,490)
Total other (expense) income	(735,490)
Net loss	(777,344)	$ (3,929,818)	$ (6,784,606)	$ 9,238,963		(3,294,265)	$ (1,475,461)
Previously Reported [Member] | ACON S2 Acquisition Corp [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Loss from operations	(41,854)					(708,829)
Other Nonoperating Income (Expense) [Abstract]
Financing costs—derivative warrant liabilities						0
Net loss	(41,854)					(704,375)
Revision of Prior Period, Adjustment [Member] | ACON S2 Acquisition Corp [Member]
Other Nonoperating Income (Expense) [Abstract]
Financing costs—derivative warrant liabilities	(735,490)					(735,490)
Total other (expense) income	(735,490)
Net loss	$ (735,490)					$ (2,589,890)
Common Class A [Member] | ACON S2 Acquisition Corp [Member]
Other Nonoperating Income (Expense) [Abstract]
Basic and diluted weighted average shares outstanding	3,787,879	25,000,000				16,139,241	25,000,000
Basic and diluted net income per share	$ (0.08)	$ (0.13)				$ (0.15)	$ (0.05)
Common Class A [Member] | ACON S2 Acquisition Corp [Member] | Amendment One [Member]
Other Nonoperating Income (Expense) [Abstract]
Basic and diluted weighted average shares outstanding	21,810,415
Common Class A [Member] | Previously Reported [Member] | ACON S2 Acquisition Corp [Member]
Other Nonoperating Income (Expense) [Abstract]
Basic and diluted weighted average shares outstanding	21,810,415					21,719,416
Basic and diluted net income per share	$ 0					$ 0
Common Class A [Member] | Revision of Prior Period, Adjustment [Member] | ACON S2 Acquisition Corp [Member]
Other Nonoperating Income (Expense) [Abstract]
Basic and diluted weighted average shares outstanding	(18,022,536)					(5,580,185)
Basic and diluted net income per share	$ (0.08)					$ (0.15)
Common Class B [Member] | ACON S2 Acquisition Corp [Member]
Other Nonoperating Income (Expense) [Abstract]
Basic and diluted weighted average shares outstanding	6,250,000	6,250,000				6,250,000	6,250,000
Basic and diluted net income per share	$ (0.08)	$ (0.13)				$ (0.15)	$ (0.05)
Common Class B [Member] | ACON S2 Acquisition Corp [Member] | Amendment One [Member]
Other Nonoperating Income (Expense) [Abstract]
Basic and diluted weighted average shares outstanding	6,732,994
Basic and diluted net income per share	$ (0.12)
Common Class B [Member] | Previously Reported [Member] | ACON S2 Acquisition Corp [Member]
Other Nonoperating Income (Expense) [Abstract]
Basic and diluted weighted average shares outstanding	6,732,994					8,310,766
Basic and diluted net income per share	$ (0.12)					$ (0.40)
Common Class B [Member] | Previously Reported [Member] | ACON S2 Acquisition Corp [Member] | Amendment One [Member]
Other Nonoperating Income (Expense) [Abstract]
Basic and diluted weighted average shares outstanding	6,437,865
Basic and diluted net income per share	$ (0.01)
Common Class B [Member] | Revision of Prior Period, Adjustment [Member] | ACON S2 Acquisition Corp [Member]
Other Nonoperating Income (Expense) [Abstract]
Basic and diluted weighted average shares outstanding	(482,994)					(2,060,766)
Basic and diluted net income per share	$ 0.04					$ 0.25

Restatement of Financial Sta_10

Restatement of Financial Statements - Schedule of Unaudited Quarterly Financial Information for Restatement and Revision of Unaudited Condensed Statement of Cash Flows (Details) - USD ($)	2 Months Ended	3 Months Ended				5 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Dec. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net loss		$ (51,325,000)			$ (2,771,000)		$ (296,685,000)	$ (6,200,000)	$ (30,419,000)	$ (11,467,000)
Net cash used in operating activities							(28,343,000)	(12,109,000)	(16,645,000)	(6,675,000)
Net cash used in investing activities							(288,000)	(464,000)	(502,000)	(851,000)
Net cash provided by financing activities							31,548,000	4,792,000	4,722,000	22,254,000
Net change in cash							2,917,000	$ (7,781,000)	$ (12,425,000)	$ 14,728,000
ACON S2 Acquisition Corp [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net loss	$ (777,344)	$ (3,929,818)	$ (6,784,606)	$ 9,238,963		$ (3,294,265)	(1,475,461)
Adjustments to reconcile net loss to net cash used in operating activities	751,490					2,601,436
Net cash used in operating activities	(26,800)					(976,685)	(468,896)
Net cash used in investing activities	(250,000,000)					(250,000,000)
Net cash provided by financing activities	251,773,258					251,446,758
Net change in cash	1,746,458					470,073	$ (468,896)
Previously Reported [Member] | ACON S2 Acquisition Corp [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net loss	(41,854)					(704,375)
Adjustments to reconcile net loss to net cash used in operating activities	16,000					11,546
Net cash used in operating activities	(26,800)					(976,685)
Net cash used in investing activities	(250,000,000)					(250,000,000)
Net cash provided by financing activities	251,773,258					251,446,758
Net change in cash	1,746,458					470,073
Revision of Prior Period, Adjustment [Member] | ACON S2 Acquisition Corp [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net loss	(735,490)					(2,589,890)
Adjustments to reconcile net loss to net cash used in operating activities	$ 735,490					$ 2,589,890

Restatement of Financial Sta_11

Restatement of Financial Statements - Additional Information (Details) - USD ($)	Sep. 21, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	May 07, 2021
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Ordinary shares, par value		$ 0.0001		$ 0.0001	$ 0.0001		$ 0.0001	$ 0.0001	$ 0.0001
Increase to derivative warrant liabilities		$ 2,949,000	$ (24,000)		$ 17,753,000	$ (78,000)	$ 1,296,000	$ 341,000
ACON S2 Acquisition Corp [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Warrants price per unit		$ 11.50		$ 11.50	$ 11.50		$ 11.50
Warrants expiration term	5 years
Increase to derivative warrant liabilities	$ 19,500,000	$ 2,232,690		$ 1,854,400	$ (1,137,350)
ACON S2 Acquisition Corp [Member] | Class A ordinary shares
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Ordinary shares, par value	$ 0.0001	$ 0.0001	$ 0.0001	$ 0.0001	$ 0.0001	$ 0.0001	$ 0.0001
Warrants price per unit	$ 11.50
ACON S2 Acquisition Corp [Member] | Initial Public Offering
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Number of units issued	25,000,000
ACON S2 Acquisition Corp [Member] | Initial Public Offering | Class A ordinary shares
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Warrants price per unit	$ 11.50

Restatement of Previously Iss_3

Restatement of Previously Issued Financial Statements -Summary of Financial Statement Adjustments Related to Restatement (Detail) - USD ($)	2 Months Ended	3 Months Ended				5 Months Ended	6 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Dec. 31, 2020	Jun. 30, 2021	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Sep. 21, 2020	Jul. 20, 2020	Jun. 30, 2020	Dec. 31, 2018
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Total assets		$ 17,824,000				$ 9,023,000		$ 17,824,000		$ 9,023,000	$ 21,140,000
Total liabilities		285,412,000				36,911,000		285,412,000		36,911,000	18,926,000
Class A ordinary shares subject to possible redemption						215,583,980				215,583,980
Ordinary shares		1,000				1,000		1,000		1,000	1,000
Additional paid-in capital		2,516,000				1,079,000		2,516,000		1,079,000	762,000
Accumulated deficit		(360,178,000)				(63,493,000)		(360,178,000)		(63,493,000)	(33,074,000)
Total shareholders' equity	$ (38,101,000)	(357,661,000)	$ (306,606,000)		$ (38,101,000)	(62,260,000)	$ (306,606,000)	(357,661,000)	$ (38,101,000)	(62,260,000)	(32,158,000)			$ (35,407,000)	$ (20,793,000)
Remeasurement adjustment on Class A ordinary shares subject to possible redemption	26,146,752
Total liabilities and shareholders' equity		$ 17,824,000				9,023,000		$ 17,824,000		$ 9,023,000	$ 21,140,000
Weighted average shares outstanding of basic and diluted		8,823,458			7,102,536			8,458,054	7,099,532	7,108,389	7,043,575
Basic and diluted net loss per share		$ (5.82)			$ (0.39)			$ (35.08)	$ (0.87)	$ (4.28)	$ (1.64)
ACON S2 Acquisition Corp [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Total assets	252,167,049	$ 250,218,951			$ 252,167,049	250,827,490		$ 250,218,951	$ 252,167,049	$ 250,827,490		$ 252,174,258
Total liabilities	29,066,145	31,110,429			29,066,145	30,243,507		31,110,429	29,066,145	30,243,507		29,049,500
Class A ordinary shares subject to possible redemption	250,000,000				250,000,000	250,000,000			250,000,000	250,000,000		250,000,000
Preference shares	0				0				0
Additional paid-in capital		94				94		94		94
Accumulated deficit	(26,899,815)				(26,899,815)	(29,416,642)			(26,899,815)	(29,416,642)		(26,875,961)
Total shareholders' equity	(26,899,096)	(30,891,478)	(26,961,660)	$ (20,177,054)	(26,899,096)	(29,416,017)	(26,961,660)	(30,891,478)	(26,899,096)	(29,416,017)		(26,875,242)
Remeasurement adjustment on Class A ordinary shares subject to possible redemption	(26,146,752)
Total liabilities and shareholders' equity	252,167,049	250,218,951			252,167,049	250,827,490		250,218,951	252,167,049	250,827,490		252,174,258
ACON S2 Acquisition Corp [Member] | Common Class A [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Class A ordinary shares subject to possible redemption	$ 218,100,900	250,000,000			218,100,900	250,000,000		250,000,000	218,100,900	250,000,000
Ordinary shares
Remeasurement adjustment on Class A ordinary shares subject to possible redemption						$ 26,146,752		$ 26,146,752
Weighted average shares outstanding of basic and diluted	3,787,879	25,000,000				16,139,241		25,000,000
Basic and diluted net loss per share	$ (0.08)	$ (0.13)				$ (0.15)		$ (0.05)
ACON S2 Acquisition Corp [Member] | Common Class B [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Ordinary shares	$ 719	$ 625			719	$ 625		$ 625	719	625		719
Total shareholders' equity	$ 719	$ 625	625	625	719	$ 625	625	$ 625	719	625
Weighted average shares outstanding of basic and diluted	6,250,000	6,250,000				6,250,000		6,250,000
Basic and diluted net loss per share	$ (0.08)	$ (0.13)				$ (0.15)		$ (0.05)
ACON S2 Acquisition Corp [Member] | Redeemable Class A Common Stock [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Weighted average shares outstanding of basic and diluted						16,139,241
Basic and diluted net loss per share						$ (0.15)
ACON S2 Acquisition Corp [Member] | Previously Reported [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Total assets	$ 252,167,049		250,304,732	250,663,379	252,167,049	$ 250,827,490	250,304,732		252,167,049	250,827,490		252,174,258
Total liabilities	29,066,145		27,266,392	20,840,433	29,066,145	30,243,507	27,266,392		29,066,145	30,243,507		29,049,500
Class A ordinary shares subject to possible redemption	218,100,900		218,038,330	224,822,940	218,100,900	215,583,980	218,038,330		218,100,900	215,583,980		218,124,750
Preference shares	0		0	0	0	0	0		0	0		0
Additional paid-in capital	5,776,310		6,784,542	0	5,776,310	8,293,299	6,784,542		5,776,310	8,293,299		5,747,460
Accumulated deficit	(777,344)		(1,785,477)	4,999,129	(777,344)	(3,294,265)	(1,785,477)		(777,344)	(3,294,265)		(748,490)
Total shareholders' equity	5,000,004		5,000,010	5,000,006	5,000,004	5,000,003	5,000,010		5,000,004	5,000,003		5,000,008
Sale of units in initial public offering, gross	237,500,000					237,500,000
Offering costs	13,646,752					13,646,752
Remeasurement adjustment on Class A ordinary shares subject to possible redemption	0					0
Shares subject to possible redemption	218,100,900			(9,238,960)		(215,583,980)	6,784,610
Total liabilities and shareholders' equity	252,167,049		250,304,732	250,663,379	252,167,049	250,827,490	250,304,732		252,167,049	250,827,490		252,174,258
ACON S2 Acquisition Corp [Member] | Previously Reported [Member] | Common Class A [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Class A ordinary shares subject to possible redemption	237,600,900				237,600,900	236,938,380			237,600,900	236,938,380
Ordinary shares	$ 319		320	252	319	$ 344	320		319	344		319
Weighted average shares outstanding of basic and diluted	21,810,415					21,719,416
Basic and diluted net loss per share	$ 0					$ 0
ACON S2 Acquisition Corp [Member] | Previously Reported [Member] | Common Class B [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Ordinary shares	$ 719		625	625	719	$ 625	625		719	625		719
Weighted average shares outstanding of basic and diluted	6,732,994					8,310,766
Basic and diluted net loss per share	$ (0.12)					$ (0.40)
ACON S2 Acquisition Corp [Member] | Previously Reported [Member] | Redeemable Class A Common Stock [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Earnings (loss) allocable to ordinary shares	$ 3,841		$ 3,293	$ 3,321		$ 0	$ 6,514
Weighted average shares outstanding of basic and diluted	21,810,415		22,474,838	21,568,664		21,719,426	22,024,254
Basic and diluted net loss per share	$ 0		$ 0	$ 0		$ 0	$ 0
ACON S2 Acquisition Corp [Member] | Previously Reported [Member] | Non Redeemable Class B Common Stock [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Earnings (loss) allocable to ordinary shares	$ (777,344)		$ (6,787,899)	$ 9,235,642		$ (3,298,105)	$ 2,447,843
Weighted average shares outstanding of basic and diluted	6,732,994		8,775,162	9,681,336		8,310,766	9,225,746
Basic and diluted net loss per share	$ (0.12)		$ (0.77)	$ 0.95		$ (0.40)	$ 0.27
ACON S2 Acquisition Corp [Member] | Revision of Prior Period, Adjustment [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Total assets						$ 0				0
Class A ordinary shares subject to possible redemption	$ 31,899,100		$ 31,961,670	$ 25,177,060	31,899,100	34,416,020	$ 31,961,670		31,899,100	34,416,020		31,875,250
Preference shares	0		0	0	0	0	0		0	0		0
Additional paid-in capital	(5,776,310)		(6,784,542)	0	(5,776,310)	(8,293,299)	(6,784,542)		(5,776,310)	(8,293,299)		(5,747,460)
Accumulated deficit	(26,122,471)		(25,176,808)	(25,176,808)	(26,122,471)	(26,122,377)	(25,176,808)		(26,122,471)	(26,122,377)		(26,127,471)
Total shareholders' equity	(31,899,100)		(31,961,670)	(25,177,060)	(31,899,100)	(34,416,020)	(31,961,670)		(31,899,100)	(34,416,020)		(31,875,250)
Sale of units in initial public offering, gross	(237,500,000)					(237,500,000)
Offering costs	13,646,752					13,646,752
Remeasurement adjustment on Class A ordinary shares subject to possible redemption	(26,146,752)					(26,146,752)
Shares subject to possible redemption	(218,100,900)			9,238,960		215,583,980	(6,784,610)
Total liabilities and shareholders' equity	0		0	0	0	0	0		0	0		0
ACON S2 Acquisition Corp [Member] | Revision of Prior Period, Adjustment [Member] | Common Class A [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Class A ordinary shares subject to possible redemption	(19,500,000)				(19,500,000)	(21,354,400)			(19,500,000)	(21,354,400)
Ordinary shares	$ (319)		(320)	(252)	(319)	$ (344)	(320)		(319)	(344)		(319)
Weighted average shares outstanding of basic and diluted	(18,022,536)					(5,580,185)
Basic and diluted net loss per share	$ (0.08)					$ (0.15)
ACON S2 Acquisition Corp [Member] | Revision of Prior Period, Adjustment [Member] | Common Class B [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Ordinary shares	$ 0		0	0	0	$ 0	0		0	0		0
Weighted average shares outstanding of basic and diluted	(482,994)					(2,060,766)
Basic and diluted net loss per share	$ 0.04					$ 0.25
ACON S2 Acquisition Corp [Member] | Revision of Prior Period, Adjustment [Member] | Redeemable Class A Common Stock [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Earnings (loss) allocable to ordinary shares	$ (2,378,506)		$ (5,430,978)	$ 7,387,849		$ (293,337)	$ 1,956,972
Weighted average shares outstanding of basic and diluted	(18,022,536)		2,525,162	3,431,336		(5,580,185)	2,975,746
Basic and diluted net loss per share	$ (0.08)		$ (0.22)	$ 0.30		$ (0.15)	$ 0.08
ACON S2 Acquisition Corp [Member] | Revision of Prior Period, Adjustment [Member] | Non Redeemable Class B Common Stock [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Earnings (loss) allocable to ordinary shares	$ 293,337		$ 5,430,978	$ (7,387,849)		$ 2,378,505	$ (1,956,972)
Weighted average shares outstanding of basic and diluted	(482,994)		(2,525,162)	(3,431,336)		(2,060,766)	(2,975,746)
Basic and diluted net loss per share	$ 0.04		$ 0.55	$ (0.65)		$ 0.25	$ (0.19)
ACON S2 Acquisition Corp [Member] | As Restated [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Total assets	$ 252,167,049		$ 250,304,732	$ 250,663,379	252,167,049	$ 250,827,490	$ 250,304,732		252,167,049	250,827,490		252,174,258
Total liabilities	29,066,145		27,266,392	20,840,433	29,066,145	30,243,507	27,266,392		29,066,145	30,243,507		29,049,500
Class A ordinary shares subject to possible redemption	250,000,000		250,000,000	250,000,000	250,000,000	250,000,000	250,000,000		250,000,000	250,000,000		250,000,000
Preference shares	0		0	0	0	0	0		0	0		0
Additional paid-in capital	0		0	0	0	0	0		0	0		0
Accumulated deficit	(26,899,815)		(26,962,285)	(20,177,679)	(26,899,815)	(29,416,642)	(26,962,285)		(26,899,815)	(29,416,642)		(26,875,961)
Total shareholders' equity	(26,899,096)		(26,961,660)	(20,177,054)	(26,899,096)	(29,416,017)	(26,961,660)		(26,899,096)	(29,416,017)		(26,875,242)
Sale of units in initial public offering, gross	0					0
Offering costs	0					0
Remeasurement adjustment on Class A ordinary shares subject to possible redemption	(26,146,752)					(26,146,752)
Shares subject to possible redemption				0			0
Total liabilities and shareholders' equity	252,167,049		250,304,732	250,663,379	252,167,049	250,827,490	250,304,732		252,167,049	250,827,490		252,174,258
ACON S2 Acquisition Corp [Member] | As Restated [Member] | Common Class A [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Ordinary shares	0		0	0	0	0	0		0	0		0
ACON S2 Acquisition Corp [Member] | As Restated [Member] | Common Class B [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Ordinary shares	719		625	625	$ 719	625	625		$ 719	$ 625		$ 719
ACON S2 Acquisition Corp [Member] | As Restated [Member] | Redeemable Class A Common Stock [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Earnings (loss) allocable to ordinary shares	$ (2,374,665)		$ (5,427,685)	$ 7,391,170		$ (293,337)	$ 1,963,486
Weighted average shares outstanding of basic and diluted	3,787,879		25,000,000	25,000,000		16,139,241	25,000,000
Basic and diluted net loss per share	$ (0.08)		$ (0.22)	$ 0.30		$ (0.15)	$ 0.08
ACON S2 Acquisition Corp [Member] | As Restated [Member] | Non Redeemable Class B Common Stock [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Earnings (loss) allocable to ordinary shares	$ (484,007)		$ (1,356,921)	$ 1,847,793		$ (919,600)	$ 490,871
Weighted average shares outstanding of basic and diluted	6,250,000		6,250,000	6,250,000		6,250,000	6,250,000
Basic and diluted net loss per share	$ (0.08)		$ (0.22)	$ 0.30		$ (0.15)	$ 0.08

Restatement of Previously Iss_4

Restatement of Previously Issued Financial Statements - Additional Information (Detail) - ACON S2 Acquisition Corp [Member]	9 Months Ended
	Sep. 30, 2021USD ($)
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Net tangible assets	$ 5,000,001
Revision of Prior Period, Reclassification, Adjustment [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Increase decrease in additional paid-in capital	5,700,000
Increase decrease in accumulated deficit	26,100,000
Reclassifications of Permanent Equity to Temporary Equity	$ 31,900,000

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	3 Months Ended		5 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Summary Of Significant Accounting Policies [Line Items]
Warrants issued				585,145
Unrecognized tax benefits			$ 47,000			$ 47,000	$ 12,000	$ 0
Accrued for payment of interest and penalties			$ 0			$ 0	$ 0
Antidilutive securities	41,561,044	38,166,748		41,561,044	38,166,748	38,496,099	36,638,554
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]			true			true
ACON S2 Acquisition Corp [Member]
Summary Of Significant Accounting Policies [Line Items]
Cash equivalents	$ 0		$ 0	$ 0		$ 0
Assets Held-in-trust, Noncurrent	250,016,847		250,004,454	250,016,847		250,004,454
Concentrations of credit risk federal depository insurance coverage limit	250,000		250,000	250,000		250,000
Unrecognized tax benefits	0		0	0		0
Accrued for payment of interest and penalties	$ 0		$ 0	$ 0		$ 0
IPO [Member] | ACON S2 Acquisition Corp [Member]
Summary Of Significant Accounting Policies [Line Items]
Warrants issued			8,333,333
Private Placement [Member] | ACON S2 Acquisition Corp [Member]
Summary Of Significant Accounting Policies [Line Items]
Warrants issued			4,666,667
Accounting Standards Update 2020-06 [Member] | ACON S2 Acquisition Corp [Member]
Summary Of Significant Accounting Policies [Line Items]
Change in Accounting Principle, Accounting Standards Update, Adopted [true false]	true			true
Change in Accounting Principle, Accounting Standards Update, Adoption Date	Jan. 1, 2021			Jan. 1, 2021
Change in Accounting Principle, Accounting Standards Update, Immaterial Effect [true false]	true			true
Warrant [Member]
Summary Of Significant Accounting Policies [Line Items]
Antidilutive securities	0	1,738,382		0	1,738,382	1,738,382	1,668,382
Warrant [Member] | ACON S2 Acquisition Corp [Member]
Summary Of Significant Accounting Policies [Line Items]
Antidilutive securities			13,000,000	13,000,000
Class A Ordinary Shares Subject To Possible Redemption [Member] | ACON S2 Acquisition Corp [Member]
Summary Of Significant Accounting Policies [Line Items]
Temporary equity shares subject to possible redemption	25,000,000		25,000,000	25,000,000		25,000,000
Maximum [Member] | ACON S2 Acquisition Corp [Member]
Summary Of Significant Accounting Policies [Line Items]
Cash and cash equivalents original maturity term			3 months	3 months
Maximum [Member] | US Treasury Securities [Member] | ACON S2 Acquisition Corp [Member]
Summary Of Significant Accounting Policies [Line Items]
Investments held in Trust Account, original maturity				185 days

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Summary of Basic and Diluted Net Income (Loss) per Ordinary Share (Details) - USD ($)	2 Months Ended	3 Months Ended		5 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Earnings Per Share Basic And Diluted [Line Items]
Allocation of net loss							$ (30,419,000)	$ (11,546,000)
Basic and diluted weighted average common shares outstanding		8,823,458	7,102,536		8,458,054	7,099,532	7,108,389	7,043,575
Basic and diluted net loss per common share		$ (5.82)	$ (0.39)		$ (35.08)	$ (0.87)	$ (4.28)	$ (1.64)
Common Class A [Member] | ACON S2 Acquisition Corp [Member]
Earnings Per Share Basic And Diluted [Line Items]
Allocation of net loss	$ (293,337)	$ (3,143,854)		$ (2,374,665)	$ (1,180,369)
Basic and diluted weighted average common shares outstanding	3,787,879	25,000,000		16,139,241	25,000,000
Basic and diluted net loss per common share	$ (0.08)	$ (0.13)		$ (0.15)	$ (0.05)
Common Class B [Member] | ACON S2 Acquisition Corp [Member]
Earnings Per Share Basic And Diluted [Line Items]
Allocation of net loss	$ (484,007)	$ (785,964)		$ (919,600)	$ (295,092)
Basic and diluted weighted average common shares outstanding	6,250,000	6,250,000		6,250,000	6,250,000
Basic and diluted net loss per common share	$ (0.08)	$ (0.13)		$ (0.15)	$ (0.05)

Initial Public Offering - Addit

Initial Public Offering - Additional Information (Detail) - USD ($)	Sep. 21, 2020	Sep. 30, 2020	Dec. 31, 2020	Sep. 30, 2021
Initial Public Offering [Line Items]
Deferred underwriting commissions	$ 8,800,000
ACON S2 Acquisition Corp [Member]
Initial Public Offering [Line Items]
Proceeds received from initial public offering, gross		$ 250,000,000	$ 250,000,000
Offering costs		$ 5,140,200	$ 5,466,700
Exercise price per share			$ 11.50	$ 11.50
ACON S2 Acquisition Corp [Member] | Class A ordinary shares
Initial Public Offering [Line Items]
Proceeds received from initial public offering, gross			$ 250,000,000	$ 250,000,000
Offering costs			$ 13,646,752	$ 13,646,752
Exercise price per share	$ 11.50
ACON S2 Acquisition Corp [Member] | Initial Public Offering
Initial Public Offering [Line Items]
Number of units issued	25,000,000
Units issued, price per unit	$ 10
Proceeds received from initial public offering, gross	$ 250,000,000
Offering costs	14,400,000
Deferred underwriting commissions	$ 8,800,000
Warrants description				Each Unit consisted of one Class A ordinary share and one-third of one redeemable warrant (“Public Warrant”). Each whole Public Warrant entitles the holder to purchase one Class A ordinary share at an exercise price of $11.50 per share, subject to adjustment (see Note 10).
ACON S2 Acquisition Corp [Member] | Initial Public Offering | Class A ordinary shares
Initial Public Offering [Line Items]
Exercise price per share	$ 11.50

Private Placement - Additional

Private Placement - Additional Information (Details) - USD ($)	Sep. 21, 2020	Dec. 31, 2020	Sep. 30, 2021
Private Placement [Line Items]
Warrants issued			585,145
ACON S2 Acquisition Corp [Member]
Private Placement [Line Items]
Warrants price per unit		$ 11.50	$ 11.50
ACON S2 Acquisition Corp [Member] | Class A ordinary shares
Private Placement [Line Items]
Warrants price per unit	$ 11.50
Gross proceeds from private placement		$ 12,500,000	$ 12,500,000
ACON S2 Acquisition Corp [Member] | Private Placement
Private Placement [Line Items]
Warrants issued		4,666,667
Period to issue warrant after completion of initial business combination		30 days	30 days
ACON S2 Acquisition Corp [Member] | Private Placement | Sponsor
Private Placement [Line Items]
Warrants issued	4,666,667
Warrants price	1.50
Gross proceeds from private placement	$ 7,000,000
ACON S2 Acquisition Corp [Member] | Private Placement | Class A ordinary shares
Private Placement [Line Items]
Warrants price per unit		$ 11.50	$ 11.50

Customer Deposits - Summary of

Customer Deposits - Summary of Rollforward of Contract Balances (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020	Dec. 31, 2019
Contract with Customer, Contract Asset, Contract Liability, and Receivable [Abstract]
Customer deposits, beginning balance	$ 2,258	$ 2,207	$ 869
Additions	850	506	1,983
Cancellations		(455)	(645)
Customer deposits, ending balance	$ 3,108	$ 2,258	$ 2,207

Customer Deposits - Additional

Customer Deposits - Additional Infomation (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Revenue from Contract with Customer [Abstract]
Revenues	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0

Loss Per Share - Additional Inf

Loss Per Share - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Earnings Per Share [Abstract]
Dilutive securities	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0

Loss Per Share - Summary of Bas

Loss Per Share - Summary of Basic and Diluted Net Loss Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Earnings Per Share Basic And Diluted [Line Items]
Net loss	$ (51,325)	$ (2,771)	$ (296,685)	$ (6,200)	$ (30,419)	$ (11,467)
Series B Redeemable Convertible Preferred Stock accretion						(79)
Net Loss to Common Stockholders					$ (30,419)	$ (11,546)
Weighted-average shares outstanding – Basic and Diluted	8,823,458	7,102,536	8,458,054	7,099,532	7,108,389	7,043,575
Net loss per share – Basic and Diluted	$ (5.82)	$ (0.39)	$ (35.08)	$ (0.87)	$ (4.28)	$ (1.64)

Loss Per Share - Summary of Dil

Loss Per Share - Summary of Diluted Weighted Average Common Shares (Detail) - shares	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	41,561,044	38,166,748	41,561,044	38,166,748	38,496,099	36,638,554
Stock options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	2,792,655	3,562,417	2,792,655	3,562,417	3,891,768	2,104,223
Preferred stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	38,768,389	32,865,949	38,768,389	32,865,949	32,865,949	32,865,949
Warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	0	1,738,382	0	1,738,382	1,738,382	1,668,382

Prepaid Expenses And Other Cu_3

Prepaid Expenses And Other Current Assets - Summary of Prepaid Expenses and Other Current Assets (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Dec. 31, 2019
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Vendor advances		$ 473	$ 507
IT services and other office expenses		157	50
Insurance		107	41
Other		56	60
Total prepaids and other current assets	$ 6,506	$ 793	$ 658

Property And Equipment, Net - S

Property And Equipment, Net - Summary of Property and Equipment (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property, plant and equipment		$ 2,984	$ 2,375
Less accumulated depreciation		(1,148)	(712)
Total property and equipment, net	$ 2,007	1,836	1,663
Machinery and equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment		2,217	1,430
Furniture and fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment		90	60
Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment		$ 677	496
Construction in process [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment			$ 389

Property And Equipment, Net - A

Property And Equipment, Net - Additional Information (Detail) - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 404	$ 306	$ 436	$ 260

Accrued and Other Current Lia_3

Accrued and Other Current Liabilities - Summary of Accrued and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Payables and Accruals [Abstract]
Payroll and related benefits	$ 777	$ 351
Materials and related purchases	464	474
Deferred rent	462	524
Professional & consulting fees	248	103
Customer refund		352
Other	243	22
Total accrued and other current liabilities	$ 2,194	$ 1,826

Leases - Summary of Future Mini

Leases - Summary of Future Minimum Lease Payments Under Non-cancelable Operating Lease Agreements (Detail) $ in Thousands	Dec. 31, 2020USD ($)
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2021	$ 840
2022	865
2023	891
2024	917
2025	157
Future Operating Lease Payments	$ 3,670

Leases - Additional Information

Leases - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Jan. 01, 2021
Operating Leases, Rent Expense	$ 837	$ 1,048
Lessee, Operating Lease, Renewal Term			5 years
Wilsonville [Member]
Lessee, Operating Lease, Renewal Term	60 months
Lessee, Operating Lease,Expiration date	Feb. 28, 2025

Borrowings - Summary of Long Te

Borrowings - Summary of Long Term Debt (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Total notes payable	$ 25,668	$ 5,697	$ 828
Less current portion of notes payable	23,415	5,678	365
Long-term notes payable, net of current portion	2,253	19	463
Notes payable [Member]
Debt Instrument [Line Items]
Total notes payable	4,236	4,761	$ 828
Bridge loan [Member]
Debt Instrument [Line Items]
Total notes payable	$ 21,432
PPP loan [Member]
Debt Instrument [Line Items]
Total notes payable		$ 936

Borrowings - Summary of Maturit

Borrowings - Summary of Maturities of Long Term Debt (Detail) - Term Loan for Equipment [Member] $ in Thousands	Jan. 01, 2021USD ($)
Debt Instrument [Line Items]
2021	$ 48
2022	18
2023	1
Total principal payments on notes payable	$ 67

Borrowings - Additional Informa

Borrowings - Additional Information (Detail) - USD ($)

Jul. 31, 2021

Mar. 31, 2020

Sep. 30, 2021

Sep. 30, 2020

Sep. 30, 2021

Sep. 30, 2020

Dec. 31, 2020

Dec. 31, 2019

Dec. 31, 2018

Apr. 19, 2020

Mar. 27, 2020

Sep. 30, 2019

Jul. 31, 2018

Debt Instrument [Line Items]

Notes payable current and non current

$ 25,668,000

$ 25,668,000

$ 5,697,000

$ 828,000

Period during which the company may apply for loan forgiveness

2 years

Gain loss on extinguishment of debt

948,000

$ (62,000)

$ (62,000)

(116,000)

Interest expense

1,582,000

$ 38,000

1,693,000

106,000

132,000

1,019,000

Debt Instrument, Decrease, Forgiveness

948

Notes payable, non-current

2,253,000

2,253,000

19,000

463,000

Convertible Notes 2018 and 2019 [Member] | Principal [Member] | Series C One Redeemable Convertible Preferred Stock [Member]

Debt Instrument [Line Items]

Debt instrument converted converted instrument amount

9,240,000

Convertible Notes 2018 and 2019 [Member] | Interest [Member] | Series C One Redeemable Convertible Preferred Stock [Member]

Debt Instrument [Line Items]

Debt instrument converted converted instrument amount

606,000

Subjective Acceleration Clause [Member]

Debt Instrument [Line Items]

Long term debt contingent principal amount payable

$ 4,067,000

$ 4,067,000

$ 4,583,000

Warrants to Purchase Series B Redeemable Convertible Preferred Stock [Member]

Debt Instrument [Line Items]

Class of warrants or rights term

10 years

10 years

Warrants to Purchase Series C Redeemable Convertible Preferred Stock [Member]

Debt Instrument [Line Items]

Class of warrants or rights term

10 years

10 years

10 years

PPP loan [Member]

Debt Instrument [Line Items]

Notes payable current and non current

$ 936,000

Gain loss on extinguishment of debt

$ 948,000

$ 948,000

Debt Instrument, Decrease, Forgiveness

$ 936,000

Accrued Interest

12,000

PPP loan [Member] | Subjective Acceleration Clause [Member]

Debt Instrument [Line Items]

Long term debt contingent principal amount payable

$ 943,000

$ 943,000

$ 943,000

PPP loan [Member] | Covid 19 [Member]

Debt Instrument [Line Items]

Debt instrument face value

$ 936,000

$ 936,000

Long term debt of maturity

Apr. 20, 2022

Apr. 20, 2022

Apr. 20, 2022

Long term debt fixed interest rate percentage

1.00%

1.00%

1.00%

Minimum percentage of debt to be used towards payroll for forgiveness of the loan

60.00%

60.00%

Remaining percentage of loan that may be used for mortgage interest rent and utility

40.00%

40.00%

Period during which the usage of debt shall be monitored

24 weeks

24 weeks

Thousand Dollar Notes Payable [Member] | Loan Secured By All The Property Of The Company Except Intellectual Property [Member]

Debt Instrument [Line Items]

Debt instrument face value

$ 1,000,000

Thousand Dollar Notes Payable [Member] | Loan Secured By All The Property Of The Company Except Intellectual Property [Member] | Warrants to Purchase Series B Redeemable Convertible Preferred Stock [Member]

Debt Instrument [Line Items]

Interest expense

$ 0

$ 0

$ 4,000

Thousand Dollar Notes Payable [Member] | Loan Secured By All The Property Of The Company Except Intellectual Property [Member] | Warrants to Purchase Series C Redeemable Convertible Preferred Stock [Member]

Debt Instrument [Line Items]

Interest expense

$ 0

$ 4,000

21,000

Thousand Dollar Notes Payable [Member] | Loan Secured By All The Property Of The Company Except Intellectual Property [Member] | Prime Rate [Member]

Debt Instrument [Line Items]

Debt instrument variable interest rate spread

0.50%

0.50%

Long term debt variable interest rate percentage

2.75%

2.75%

2.75%

Thousand Dollar Notes Payable [Member] | Loan Secured By All The Property Of The Company Except Intellectual Property [Member] | Deferral Agreement [Member]

Debt Instrument [Line Items]

Long term debt of maturity

Jan. 1, 2022

Four Thousand Dollar Notes Payable [Member] | Loan Secured By All The Property Of The Company Except Intellectual Property [Member]

Debt Instrument [Line Items]

Debt instrument face value

$ 4,000,000

Percentage change in the present value of cash flows

10.00%

Proceeds from notes payable medium term

$ 4,000,000

Gain loss on extinguishment of debt

$ 62,000

Four Thousand Dollar Notes Payable [Member] | Loan Secured By All The Property Of The Company Except Intellectual Property [Member] | Warrants to Purchase Series B Redeemable Convertible Preferred Stock [Member]

Debt Instrument [Line Items]

Class of warrants or rights number of securities covered by the warrants or rights

68,000

Class of warrants or rights exercise price

$ 1.42

Redeemable non controlling interest equity preferred fair value

$ 55,000

Class of warrants or rights term

10 years

Four Thousand Dollar Notes Payable [Member] | Loan Secured By All The Property Of The Company Except Intellectual Property [Member] | Warrants to Purchase Series C Redeemable Convertible Preferred Stock [Member]

Debt Instrument [Line Items]

Class of warrants or rights number of securities covered by the warrants or rights

70,000

Class of warrants or rights exercise price

$ 1.84

Redeemable non controlling interest equity preferred fair value

$ 44,000

Class of warrants or rights term

10 years

10 years

Four Thousand Dollar Notes Payable [Member] | Loan Secured By All The Property Of The Company Except Intellectual Property [Member] | Prime Rate [Member]

Debt Instrument [Line Items]

Long term debt variable interest rate percentage

2.75%

Four Thousand Dollar Notes Payable [Member] | Loan Secured By All The Property Of The Company Except Intellectual Property [Member] | Deferral Agreement [Member]

Debt Instrument [Line Items]

Long term debt of maturity

Jul. 1, 2023

Convertible Debt [Member] | Convertible Notes 2018 [Member]

Debt Instrument [Line Items]

Amortization of debt discount

543,000

Convertible Debt [Member] | Convertible Notes 2018 [Member] | Warrants to Purchase Redeemable Convertible Preferred Stock [Member]

Debt Instrument [Line Items]

Derivative liabilities at fair value

$ 1,421,000

Convertible Debt [Member] | Convertible Notes 2018 [Member] | 2018 Convertible Debt Automatic Conversion Rights [Member]

Debt Instrument [Line Items]

Embbeded derivative liabilities at fair value

9,000

Convertible Debt [Member] | Convertible Notes 2018 [Member] | Warrants and Emedded Derivative Liabilities [Member]

Debt Instrument [Line Items]

Financial liabilities at fair value

1,430,000

Convertible Debt [Member] | Convertible Notes 2018 [Member] | Forecast [Member]

Debt Instrument [Line Items]

Proceeds from financing

10,000,000

Convertible Debt [Member] | Convertible Notes 2018 and 2019 [Member]

Debt Instrument [Line Items]

Debt instrument face value

$ 2,722,000

$ 6,518,000

Long term debt fixed interest rate percentage

8.00%

8.00%

Unamortized debt issuance costs before amortization

$ 72,000

Amortization of debt issuance costs

27,000

Bridge loan [Member]

Debt Instrument [Line Items]

Debt instrument face value

$ 20,000,000

Notes payable current and non current

$ 21,432,000

$ 21,432,000

Long term debt fixed interest rate percentage

8.00%

Interest expense

1,432,000

1,432,000

Debt instrument, interest rate, effective percentage

2.25%

Debt instrument, frequency of periodic payment

monthly

Debt instrument interest rate paid in kind

6.75%

Long-term debt, average amount outstanding

$ 1,250,000

Debt instrument, fair value disclosure

20,000,000

20,000,000

Scanner Purchase [Member] | Term Loan for Equipment [Member]

Debt Instrument [Line Items]

Debt instrument face value

$ 79,000

Long term debt term

24 months

Notes payable current and non current

$ 0

$ 0

$ 67,000

Long term debt fixed interest rate percentage

6.90%

Machine Tool [Member] | Term Loan for Equipment [Member]

Debt Instrument [Line Items]

Debt instrument face value

$ 50,000

Long term debt term

36 months

Notes payable current and non current

$ 67,000

$ 70,000

Long term debt fixed interest rate percentage

8.10%

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($)	Nov. 01, 2017	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Commitments And Contingencies Disclosure [Line Items]
Noncancellable purchase commitments		$ 13,392,000		$ 3,410,000	$ 13,392,000		$ 3,410,000	$ 2,125,000
Cancellable purchase commitments		3,774,000		787,000	3,774,000		787,000	225,000
Standby Letters of Credit [Member]
Commitments And Contingencies Disclosure [Line Items]
Withdrawn of deposit amount	$ 200,000
Additional withdrawn amount	50,000
Long-term line of credit		125,000		325,000	125,000		325,000
Withdrawing line of credit		200,000	$ 0		200,000	$ 0
Letter of Credit [Member] | First Republic Bank [Member]
Commitments And Contingencies Disclosure [Line Items]
Line of credit facility maximum borrowing capacity	725,000			725,000			725,000	725,000
Proceeds from lines of credit							0	$ 0
Minimum [Member] | Standby Letters of Credit [Member]
Commitments And Contingencies Disclosure [Line Items]
Long-term line of credit	$ 75,000
ACON S2 Acquisition Corp [Member]
Commitments And Contingencies Disclosure [Line Items]
Deferred underwriting commissions		8,750,000	$ 8,750,000	8,750,000	$ 8,750,000	$ 8,750,000	8,750,000
Legal Fees				$ 490,000
ACON S2 Acquisition Corp [Member] | Underwriting Agreement [Member]
Commitments And Contingencies Disclosure [Line Items]
Underwriting discount description				The underwriters were entitled to an underwriting discount of $0.20 per unit, or $5.0 million in the aggregate, paid upon the closing of the Initial Public Offering. In addition, $0.35 per unit, or approximately $8.8 million in the aggregate will be payable to the underwriters for deferred underwriting commissions.	The underwriters were entitled to an underwriting discount of $0.20 per unit, or $5.0 million in the aggregate, paid upon the closing of the Initial Public Offering. In addition, $0.35 per unit, or approximately $8.8 million in the aggregate will be payable to the underwriters for deferred underwriting commissions.
Underwriting discount per unit				$ 0.20	$ 0.20
Aggregate underwriting discount				$ 5,000,000	$ 5,000,000
Deferred underwriting discount per unit				$ 0.35	$ 0.35
Deferred underwriting commissions		$ 8,800,000		$ 8,800,000	$ 8,800,000		$ 8,800,000
Over Allotment Option Expiration Date				Oct. 31, 2020
ACON S2 Acquisition Corp [Member] | Underwriting Agreement [Member] | Over-Allotment Option [Member]
Commitments And Contingencies Disclosure [Line Items]
Period Granted to Underwriter to Purchase Additional Units				45 days
ACON S2 Acquisition Corp [Member] | Underwriting Agreement [Member] | Over-Allotment Option [Member] | Maximum [Member]
Commitments And Contingencies Disclosure [Line Items]
Issuance of ordinary shares to Sponsor, Shares				3,750,000

Class A Ordinary Shares Subje_3

Class A Ordinary Shares Subject to Possible Redemption - Summary of recognized in Class A ordinary shares subject to possible redemption (Detail) - USD ($)	2 Months Ended	5 Months Ended	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2020	Sep. 30, 2021	Sep. 21, 2020
Remeasurement adjustment on Class A ordinary shares subject to possible redemption	$ 26,146,752
Class A ordinary shares subject to possible redemption		$ 215,583,980
ACON S2 Acquisition Corp [Member]
Gross Proceeds	250,000,000	250,000,000
Offering costs allocated to Class A shares subject to possible redemption	(5,140,200)	(5,466,700)
Remeasurement adjustment on Class A ordinary shares subject to possible redemption	(26,146,752)
Class A ordinary shares subject to possible redemption	250,000,000	250,000,000		$ 250,000,000
ACON S2 Acquisition Corp [Member] | Common Class A [Member]
Gross Proceeds		250,000,000	$ 250,000,000
Offering costs allocated to Class A shares subject to possible redemption		(13,646,752)	(13,646,752)
Proceeds allocated to Public Warrants at issuance		(12,500,000)	(12,500,000)
Remeasurement adjustment on Class A ordinary shares subject to possible redemption		26,146,752	26,146,752
Class A ordinary shares subject to possible redemption	$ 218,100,900	$ 250,000,000	$ 250,000,000

Class A Ordinary Shares Subje_4

Class A Ordinary Shares Subject to Possible Redemption - Additional Information (Detail) - $ / shares	May 07, 2021	Dec. 31, 2020	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Sep. 21, 2020	Dec. 31, 2019
Ordinary shares, authorized	79,000,000	79,000,000	79,000,000	79,000,000			79,000,000
Ordinary shares, par value	$ 0.0001	$ 0.0001	$ 0.0001	$ 0.0001			$ 0.0001
Ordinary shares, outstanding		7,134,668	9,125,954	7,134,668			7,060,668
Common stock voting rights	one vote			one vote
ACON S2 Acquisition Corp [Member]
Ordinary shares, authorized		0		0
Common stock voting rights		one vote for each share	one vote for each share
Common Class A [Member] | ACON S2 Acquisition Corp [Member]
Ordinary shares, authorized		500,000,000	500,000,000	500,000,000
Ordinary shares, par value		$ 0.0001	$ 0.0001	$ 0.0001	$ 0.0001	$ 0.0001
Ordinary shares, outstanding		25,000,000	25,000,000	25,000,000
Common stock voting rights			one vote for each share

Shareholders' Equity - Addition

Shareholders' Equity - Additional Information (Details) - USD ($)	May 07, 2021	Oct. 31, 2020	Dec. 31, 2020	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Sep. 21, 2020	Dec. 31, 2019
Class of Stock [Line Items]
Preferred shares, authorized	62,072,064
Preferred shares, par value	$ 0.0001
Ordinary shares, authorized	79,000,000		79,000,000	79,000,000	79,000,000			79,000,000
Ordinary shares, par value	$ 0.0001		$ 0.0001	$ 0.0001	$ 0.0001			$ 0.0001
Ordinary shares, issued			7,134,668	9,125,954	7,134,668			7,060,668
Ordinary shares, outstanding			7,134,668	9,125,954	7,134,668			7,060,668
Common stock voting rights	one vote				one vote
ACON S2 Acquisition Corp [Member]
Class of Stock [Line Items]
Preferred shares, authorized			5,000,000	5,000,000	5,000,000
Preferred shares, par value			$ 0.0001	$ 0.0001	$ 0.0001	$ 0.0001
Preferred shares, issued			0	0	0
Preferred shares, outstanding			0	0	0
Ordinary shares, authorized			0		0
Common stock voting rights			one vote for each share	one vote for each share
Common stock, conversion basis				Class B ordinary shares convert into Class A ordinary shares at a rate of less than one-to-one.
Common Class A [Member] | ACON S2 Acquisition Corp [Member]
Class of Stock [Line Items]
Ordinary shares, authorized			500,000,000	500,000,000	500,000,000
Ordinary shares, par value			$ 0.0001	$ 0.0001	$ 0.0001	0.0001	$ 0.0001
Issued or outstanding shares			25,000,000	25,000,000	25,000,000
Ordinary shares, outstanding			25,000,000	25,000,000	25,000,000
Common stock voting rights				one vote for each share
Common Class B [Member] | ACON S2 Acquisition Corp [Member]
Class of Stock [Line Items]
Ordinary shares, authorized			50,000,000	50,000,000	50,000,000
Ordinary shares, par value			$ 0.0001	$ 0.0001	$ 0.0001	$ 0.0001
Ordinary shares, issued			6,250,000	6,250,000	6,250,000
Ordinary shares, outstanding			6,250,000	6,250,000	6,250,000
Common stock subject to forfeiture			937,500	937,500	937,500
Underwriters consideration for over allotment			$ 0	$ 0
Over-allotment expiration date			Oct. 31, 2020	Oct. 31, 2020
Common stock shares forfeited due to non-exercise of over-allotment option in full or part by underwriters		937,500	937,500	937,500
Threshold percentage of founder shares to total shares outstanding			20.00%	20.00%
Common Class B [Member] | Founder Shareholders [Member] | ACON S2 Acquisition Corp [Member]
Class of Stock [Line Items]
Equity investment, ownership percentage			20.00%	20.00%	20.00%

Derivative Warrant Liabilities

Derivative Warrant Liabilities - Additional Information (Details) - $ / shares	5 Months Ended	9 Months Ended
	Dec. 31, 2020	Sep. 30, 2021	Sep. 21, 2020	Dec. 31, 2019
Class of Warrant or Right [Line Items]
Total warrants outstanding	1,738,382	0		1,668,382
ACON S2 Acquisition Corp [Member]
Class of Warrant or Right [Line Items]
Total warrants outstanding		13,000,000
Class of warrant or right exercise price of warrants or rights	$ 11.50	$ 11.50
Minimum share price required for redemption of warrants	$ 18	$ 18
Public warrants expiration term	5 years	5 years
Number of trading days in period	10 days	10 days
Percentage of proceeds from share issuances	60.00%	60.00%
Exercise price adjustment percentage	115.00%	115.00%
Redemption trigger price adjustment percentage	180.00%	180.00%
Minimum share price required for redemption of warrants adjustments	$ 10	$ 10
Ordinary shares per warrant	$ 0.361	$ 0.361
Common Class A [Member] | ACON S2 Acquisition Corp [Member]
Class of Warrant or Right [Line Items]
Class of warrant or right exercise price of warrants or rights			$ 11.50
Number of trading days in period	20 days	20 days
Ordinary shares redemption period	30 days	30 days
Maximum [Member] | Business Acquisition [Member] | ACON S2 Acquisition Corp [Member]
Class of Warrant or Right [Line Items]
Business acquisition, share price	$ 9.20	$ 9.20
Public Warrants [Member] | ACON S2 Acquisition Corp [Member]
Class of Warrant or Right [Line Items]
Total warrants outstanding	8,333,333	8,333,333
Number of trading days in period	20 days	20 days
Number of trading days period ending on third business day	30 days	30 days
Public Warrants [Member] | Common Class A [Member] | ACON S2 Acquisition Corp [Member]
Class of Warrant or Right [Line Items]
Minimum share price required for redemption of warrants	$ 10	$ 10
Warrants redemption price per share	$ 0.10	$ 0.10
Private Placement Warrants [Member] | ACON S2 Acquisition Corp [Member]
Class of Warrant or Right [Line Items]
Total warrants outstanding	4,666,667	4,666,667
Number of trading days in period	20 days	20 days
Warrants redemption price per share	$ 0.01	$ 0.01
Number of trading days period ending on third business day	30 days
Private Placement Warrants [Member] | Common Class A [Member] | ACON S2 Acquisition Corp [Member]
Class of Warrant or Right [Line Items]
Minimum share price required for redemption of warrants	$ 18	$ 18
Number of trading days in period	20 days	20 days
Number of trading days period ending on third business day	30 days	30 days

Redeemable Convertible Prefer_3

Redeemable Convertible Preferred Stock - Additional Information (Detail) - USD ($)	May 07, 2021	Mar. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Sep. 30, 2021
Temporary Equity [Line Items]
Derivative liabilities non current			$ 22,911,000	$ 11,379,000	$ 248,450,000
Class of warrants or rights outstanding			1,738,382	1,668,382	0
Common stock, shares authorized	79,000,000		79,000,000	79,000,000	79,000,000
Common stock, par or stated value per share	$ 0.0001		$ 0.0001	$ 0.0001	$ 0.0001
Common stock voting rights	one vote		one vote
Preferred stock, shares authorized	62,072,064
Preferred stock, par or stated value per share	$ 0.0001
Warrants and rights outstanding		$ 34,613,000
Amendment to Series C Two and Series C Preferred Stock Purchase Agreement [Member]
Temporary Equity [Line Items]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights					14,365,207
Warrants to Purchase Series B Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Class of warrants or rights outstanding			1,362,771	1,362,771	0
Class of warrants or rights term					10 years
Warrants to Purchase Series B Redeemable Convertible Preferred Stock [Member] | Sixty Eight Thousand Of The Series B Redeemable Convertible Preferred Stock Warrants [Member]
Temporary Equity [Line Items]
Class of warrants or rights outstanding			68,000		68,000
Class of warrants or rights term			10 years
Warrants to Purchase Series C Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Class of warrants or rights outstanding			70,000		0
Class of warrants or rights term			10 years		10 years
Class of warrants or rights issue price per warrant			$ 1.84
Common Stock Warrants [Member]
Temporary Equity [Line Items]
Class of warrants or rights outstanding			305,611	305,611	0
Class of warrants or rights issue price per warrant			$ 0.001		$ 0.001
Future Rights to Purchase C Two Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Fair value measurement with unobservable input reconciliation recurring basis liability unrealized gain loss			$ 11,532,000	$ 0
Minimum [Member] | Warrants to Purchase Series B Redeemable Convertible Preferred Stock [Member] | Sixty Eight Thousand Of The Series B Redeemable Convertible Preferred Stock Warrants [Member]
Temporary Equity [Line Items]
Class of warrant or right exercise price of warrants or rights			$ 0.001		0.001
Minimum [Member] | Warrants to Purchase Series C Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Class of warrants or rights issue price per warrant					0.0001
Maximum [Member] | Warrants to Purchase Series B Redeemable Convertible Preferred Stock [Member] | Sixty Eight Thousand Of The Series B Redeemable Convertible Preferred Stock Warrants [Member]
Temporary Equity [Line Items]
Class of warrant or right exercise price of warrants or rights			$ 1.22		1.42
Maximum [Member] | Warrants to Purchase Series C Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Class of warrants or rights issue price per warrant					1.84
Series B Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Notice period needed to be given by the holders of temporary equity for redemption			90 days
Series B Redeemable Convertible Preferred Stock [Member] | Minimum [Member]
Temporary Equity [Line Items]
Temporary equity lock in period			5 years
Percentage of holders of temporary equity to approve redemption			66.00%
Series C-2 Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Derivative liabilities non current				11,379,000
Stock issued during period, shares, new issues		3,900,988
Common stock, par or stated value per share					$ 0.0001
Shares issued, price per share		$ 2.95
Stock issued during period, value, new issues		$ 11,500,000
Payments of stock issuance costs		$ 39,000
Class or warrants rights issued during the period		585,145
Class or warrants rights shares extinguised		3,900,988
Class of warrant or right exercise price of warrants or rights		$ 0.0001
Derivative liabilities		$ 23,152,000
Warrants and rights outstanding		$ 29,516,000
Class of Warrant or Right, Number of Securities Called by Warrants or Rights		585,145
Series C-2 Redeemable Convertible Preferred Stock [Member] | Future Rights to Purchase C Two Redeemable Convertible Preferred Stock [Member] | Series C One Investors [Member]
Temporary Equity [Line Items]
Temporary equity shares subscribed but not issued value			$ 79,999,000	$ 79,999,000
Temporary equity shares subscribed but not issued shares			27,137,000	27,137,000
Temporary equity issue price per share predetermined			$ 2.94797	$ 2.94797
Warrants [Member]
Temporary Equity [Line Items]
Warrants and rights outstanding		$ 5,097,000
Redeemable Preferred Stock [Member]
Temporary Equity [Line Items]
Class of warrants or rights outstanding					1,290,777
Third Restatement Amendment [Member] | Series A Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Temporary equity dividend per share			0.044725
Third Restatement Amendment [Member] | Series B Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Temporary equity dividend per share			0.09828
Third Restatement Amendment [Member] | Series C-1 Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Temporary equity dividend per share			0.14740
Third Restatement Amendment [Member] | Series C-2 Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Temporary equity dividend per share			$ 0.23584

Redeemable Convertible Prefer_4

Redeemable Convertible Preferred Stock - Summary of The Company's Redeemable Convertible Preferred Stock (Detail) - USD ($) $ / shares in Units, $ in Thousands	Sep. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Temporary Equity [Line Items]
Net Carrying Value	$ 90,073		$ 34,372	$ 34,372
Redeemable Preferred Stock [Member]
Temporary Equity [Line Items]
Shares Authorized	62,072,064		61,436,037	61,436,037
Shares Issued	38,768,389		32,865,949	32,865,949
Shares Outstanding	38,768,389		32,865,949	32,865,949
Net Carrying Value	$ 90,073		$ 34,372
Aggregate Liquidation Preference	$ 61,392		$ 46,391	$ 46,391
Series A Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Shares Authorized	5,941,109		5,941,109
Shares Issued	5,941,109		5,941,109
Shares Outstanding	5,941,109		5,941,109
Issuance Price	$ 0.56		$ 0.56
Net Carrying Value	$ 3,228		$ 3,228
Aggregate Liquidation Preference	$ 3,321		$ 3,321
Series B Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Shares Authorized	12,011,923		12,011,923
Shares Issued	12,005,442		10,649,152
Shares Outstanding	12,005,442		10,649,152
Issuance Price	$ 1.23		$ 1.22848
Net Carrying Value	$ 30,659		$ 12,746
Aggregate Liquidation Preference	$ 14,748		$ 13,082
Series C-1 Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Shares Authorized	16,345,688		16,345,688
Shares Issued	16,335,705		16,275,688
Shares Outstanding	16,335,705		16,275,688
Issuance Price	$ 1.84		$ 1.84248
Net Carrying Value	$ 19,178		$ 18,398
Aggregate Liquidation Preference	$ 30,098		$ 29,988
Series C-2 Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Shares Authorized	27,773,344		27,137,317
Shares Issued	4,486,133
Shares Outstanding	4,486,133
Issuance Price	$ 2.95	$ 2.94797
Net Carrying Value	$ 37,008
Aggregate Liquidation Preference	$ 13,225

Redeemable Convertible Prefer_5

Redeemable Convertible Preferred Stock - Summary of Series C-2 Redeemable Convertible Preferred Stock Purchase Right and Related Warrants (Detail)	9 Months Ended
	Sep. 30, 2021USD ($)$ / sharesshares
Disclosure of number of shares subject to and potential proceeds before and after the amendment [Line Items]
Price | $ / shares	$ 10
SeriesC2Redeemable Convertible Preferred [Member]
Disclosure of number of shares subject to and potential proceeds before and after the amendment [Line Items]
Quantity | shares	23,236,328
Price | $ / shares	$ 2.95
Proceeds | $	$ 68,499,998
Completion Of SPAC Merger [Member]
Disclosure of number of shares subject to and potential proceeds before and after the amendment [Line Items]
Proceeds | $	$ 16,001,437
Completion Of SPAC Merger [Member] | SeriesC2Warrant [Member]
Disclosure of number of shares subject to and potential proceeds before and after the amendment [Line Items]
Quantity | shares	14,365,207
Price | $ / shares	$ 0.0001
Proceeds | $	$ 1,437
Completion Of SPAC Merger [Member] | SeriesC2Redeemable Convertible Preferred [Member]
Disclosure of number of shares subject to and potential proceeds before and after the amendment [Line Items]
Quantity | shares	5,427,464
Price | $ / shares	$ 2.95
Proceeds | $	$ 16,000,000
Milestones without SPAC merger [Member] | SeriesC2Redeemable Convertible Preferred [Member]
Disclosure of number of shares subject to and potential proceeds before and after the amendment [Line Items]
Quantity | shares	22,897,111
Price | $ / shares	$ 2.95
Proceeds | $	$ 67,499,996

Redeemable Convertible Prefer_6

Redeemable Convertible Preferred Stock - Summary of The Company Periodically Issues Warrants In Conjunction With The Issuance of Preferred Stock Or Debt (Detail) - shares	Sep. 30, 2021	Dec. 31, 2020	Dec. 31, 2019
Class of Warrant or Right [Line Items]
Class Of warrants or rights outstanding	0	1,738,382	1,668,382
Common Stock Warrants [Member]
Class of Warrant or Right [Line Items]
Class Of warrants or rights outstanding	0	305,611	305,611
Series B Preferred Warrants [Member]
Class of Warrant or Right [Line Items]
Class Of warrants or rights outstanding	0	1,362,771	1,362,771
Series C Preferred Warrants [Member]
Class of Warrant or Right [Line Items]
Class Of warrants or rights outstanding	0	70,000

Redeemable Convertible Prefer_7

Redeemable Convertible Preferred Stock - Summary of The Warrant Activities (Detail)	9 Months Ended
	Sep. 30, 2021shares
Class of Warrant or Right [Line Items]
Beginning balance	1,738,382
Issued	585,145
Exercised	2,323,527
Ending balance	0
Common Stock Warrants [Member]
Class of Warrant or Right [Line Items]
Beginning balance	305,611
Issued	0
Exercised	305,611
Ending balance	0
Series B Preferred Warrants [Member]
Class of Warrant or Right [Line Items]
Beginning balance	1,362,771
Issued	0
Exercised	1,362,771
Ending balance	0
Series C Preferred Warrants [Member]
Class of Warrant or Right [Line Items]
Beginning balance	70,000
Issued	585,145
Exercised	655,145
Ending balance	0

Redeemable Convertible Prefer_8

Redeemable Convertible Preferred Stock - Summary of The Warrants Were Valued Using The Following Assumptions (Detail)	Sep. 30, 2021yr	Dec. 31, 2020yr	Dec. 31, 2019yr
At Issuance Date [Member] | Common Stock Warrants [Member] | Expected volatility [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input		0.80
At Issuance Date [Member] | Common Stock Warrants [Member] | Expected term (in years) [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input		5
At Issuance Date [Member] | Common Stock Warrants [Member] | Risk-free interest rate [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input		0.0220
At Issuance Date [Member] | Common Stock Warrants [Member] | Dividend yield [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input		0
At Issuance Date [Member] | Preferred B Warrants [Member] | Expected volatility [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input		0.80
At Issuance Date [Member] | Preferred B Warrants [Member] | Expected term (in years) [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input		5
At Issuance Date [Member] | Preferred B Warrants [Member] | Risk-free interest rate [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input		0.0273
At Issuance Date [Member] | Preferred B Warrants [Member] | Risk-free interest rate [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input		0.0220
At Issuance Date [Member] | Preferred B Warrants [Member] | Dividend yield [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input		0
At Issuance Date [Member] | Preferred C-1 Warrants [Member] | Expected volatility [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input		0.80
At Issuance Date [Member] | Preferred C-1 Warrants [Member] | Expected term (in years) [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input		3.75
At Issuance Date [Member] | Preferred C-1 Warrants [Member] | Risk-free interest rate [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input		0.0029
At Issuance Date [Member] | Preferred C-1 Warrants [Member] | Dividend yield [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input		0
Reporting Date [Member] | Preferred B Warrants [Member] | Expected volatility [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	0.80	0.80	0.80
Reporting Date [Member] | Preferred B Warrants [Member] | Expected term (in years) [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	2	2	4
Reporting Date [Member] | Preferred B Warrants [Member] | Risk-free interest rate [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input		0.0013	0.0166
Reporting Date [Member] | Preferred B Warrants [Member] | Risk-free interest rate [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	0.0028
Reporting Date [Member] | Preferred B Warrants [Member] | Risk-free interest rate [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	0.0016
Reporting Date [Member] | Preferred B Warrants [Member] | Dividend yield [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	0	0	0
Reporting Date [Member] | Preferred C-1 Warrants [Member] | Expected volatility [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	0.80	0.80	0.80
Reporting Date [Member] | Preferred C-1 Warrants [Member] | Expected term (in years) [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	2	2	4
Reporting Date [Member] | Preferred C-1 Warrants [Member] | Risk-free interest rate [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input		0.0013	0.0166
Reporting Date [Member] | Preferred C-1 Warrants [Member] | Risk-free interest rate [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	0.0028
Reporting Date [Member] | Preferred C-1 Warrants [Member] | Risk-free interest rate [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	0.0016
Reporting Date [Member] | Preferred C-1 Warrants [Member] | Dividend yield [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	0	0	0
Reporting Date [Member] | Preferred C-2 Warrants [Member] | Expected volatility [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	0.80
Reporting Date [Member] | Preferred C-2 Warrants [Member] | Expected term (in years) [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	2
Reporting Date [Member] | Preferred C-2 Warrants [Member] | Risk-free interest rate [Member] | Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	0.0028
Reporting Date [Member] | Preferred C-2 Warrants [Member] | Risk-free interest rate [Member] | Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	0.0016
Reporting Date [Member] | Preferred C-2 Warrants [Member] | Dividend yield [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants and Rights Outstanding, Measurement Input	0

Common Stock - Additional Infor

Common Stock - Additional Information (Detail) - $ / shares	May 07, 2021	Dec. 31, 2020	Sep. 30, 2021	Dec. 31, 2019
Equity [Abstract]
Common stock, shares authorized	79,000,000	79,000,000	79,000,000	79,000,000
Common stock, par or stated value per share	$ 0.0001	$ 0.0001	$ 0.0001	$ 0.0001
Common stock voting rights	one vote	one vote

Stock-based Compensation Plan -

Stock-based Compensation Plan - Additional Information (Detail) - 2014 Equity Incentive Plan [Member] - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2021	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for issuance under share-based payment arrangement	10,524,556	10,524,556	10,524,556
Description of vesting rights		Employee options generally cliff vest at the end of the first year and then 1/48th over the remaining three years.	Employee option grants generally cliff vest twenty-five percent at the end of the first year and 1/48th of the total option shares shall vest each month thereafter
Award expiration period		10 years	10 years
Share-based compensation arrangement by sharebased payment award accelerated vesting number	0	0	0	0
Aggregate intrinsic value of the options exercised			$ 48	$ 9
Weighted average estimated fair value			$ 0.65	$ 0.36
Share-based payment arrangement, nonvested award, option, cost not yet recognized, amount			$ 1,193
Share-based payment arrangement, nonvested award, cost not yet recognized, period for recognition			2 years 6 months
Share Based Payment Arrangement Excisable At The End Of First Year [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of vesting			25.00%
Share Based Payment Arrangement Excisable Per Month And Thereafter After The End Of First Year [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of vesting		0.02083%	0.02083%

Stock-based Compensation Plan_2

Stock-based Compensation Plan - Summary of Shares Available for Future Grant (Detail) - shares	Dec. 31, 2020	Dec. 31, 2019
2014 Equity Incentive Plan [Member]
Schedule Of Shares Available For Future Grant [Line Items]
Shares Available for future grant	5,993,465	7,855,010

Stock-based Compensation Plan_3

Stock-based Compensation Plan - Summary of Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jan. 01, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options Outstanding, Number of shares, Beginning balance	3,891,768	2,104,223	2,238,598
Options Outstanding, Number of shares, Granted	987,500	2,221,278	17,500
Options Outstanding, Number of shares, Exercised	1,685,675	74,000	30,000
Options Outstanding, Number of shares, Forfeited	400,938	359,733	121,875
Options Outstanding, Number of shares, Ending balance	2,792,655	3,891,768	2,104,223	2,238,598
Options Outstanding, Number of shares, Options vested and exercisable	702,291	1,918,067	1,424,380
Options Outstanding, Weighted average exercise price, Beginning balance	$ 0.44	$ 0.37	$ 0.37
Options Outstanding, Weighted average exercise price, Granted	2.57	0.49	0.45
Options Outstanding, Weighted average exercise price, Exercised	0.40	0.09	0.22
Options Outstanding, Weighted average exercise price, Forfeited	0.69	0.43	0.45
Options Outstanding, Weighted average exercise price, Ending balance	1.18	0.44	0.37	$ 0.37
Options Outstanding, Weighted average exercise price, Options vested and exercisable	$ 0.44	$ 0.39	$ 0.34
Weighted average remaining contractual term (years)	8 years 6 months 10 days	8 years 2 months 23 days	7 years 9 months 25 days	8 years 9 months 29 days
Weighted average remaining contractual term (years), Options vested and exercisable	3 years 4 months 13 days	7 years 2 months 15 days	7 years 5 months 23 days
Aggregate intrinsic values	$ 30,331	$ 4,333	$ 821	$ 332	$ 4,333
Aggregate intrinsic values, Options vested and exercisable	$ 8,150	$ 2,215	$ 604

Stock-based Compensation Plan_4

Stock-based Compensation Plan - Schedule of Share-based Payment Award, Stock Options, Valuation Assumption (Detail)	9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Risk-free rate	1.01%	1.12%	0.93%	2.63%
Expected dividends	0.00%	0.00%	0.00%	0.00%
Expected term	6 years	6 years	6 years	6 years
Expected volatility	75.00%	70.00%	71.06%	76.77%

Stock-based Compensation Plan_5

Stock-based Compensation Plan - Summary of Stock-based Compensation Expense (Detail) - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	$ 620	$ 251	$ 310	$ 175
Research and Development [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	223	54	79	59
Sales and Marketing [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	48	33	47	38
General and Administrative [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation	$ 349	$ 164	$ 184	$ 78

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail)	Sep. 21, 2020USD ($)	Sep. 30, 2021USD ($)$ / sharesshares	Sep. 30, 2020USD ($)	Dec. 31, 2020USD ($)$ / sharesshares	Sep. 30, 2021USD ($)$ / sharesshares	Sep. 30, 2020USD ($)	Dec. 31, 2020USD ($)$ / sharesshares	Dec. 31, 2019USD ($)$ / sharesshares	Jul. 27, 2020USD ($)	Dec. 31, 2018USD ($)
Fair Value Disclosures [Line Items]
Change in fair value of derivative warrant liabilities		$ 2,949,000	$ (24,000)		$ 17,753,000	$ (78,000)	$ 1,296,000	$ 341,000
Series C-2 Redeemable Convertible Preferred Stock [Member] | Future Rights to Purchase C Two Redeemable Convertible Preferred Stock [Member] | Series C One Investors [Member]
Fair Value Disclosures [Line Items]
Temporary equity shares subscribed but not issued value				$ 79,999,000			$ 79,999,000	$ 79,999,000
Temporary equity shares subscribed but not issued shares | shares				27,137,000			27,137,000	27,137,000
Temporary equity issue price per share predetermined | $ / shares				$ 2.94797			$ 2.94797	$ 2.94797
Fair Value, Inputs, Level 1, 2 and 3 [Member]
Fair Value Disclosures [Line Items]
Transfers between levels 1 ,2 and 3							$ 0	$ 0
2018 Convertible Note Automatic Conversion Rights liability [Member]
Fair Value Disclosures [Line Items]
Threshold financing trigger for conversion of convertible notes payable										$ 10,000,000
Convertible Notes Payable [Member]
Fair Value Disclosures [Line Items]
Debt instrument face value										$ 6,518,000
ACON S2 Acquisition Corp [Member]
Fair Value Disclosures [Line Items]
Debt instrument face value									$ 300,000
Fair Value, Assets, Level 3 to Level 1 Transfers, Amount					0
Change in fair value of derivative warrant liabilities	$ 19,500,000	$ 2,232,690		$ 1,854,400	$ (1,137,350)
ACON S2 Acquisition Corp [Member] | Public Warrants [Member]
Fair Value Disclosures [Line Items]
Change in fair value of derivative warrant liability				$ 2,000,000
ACON S2 Acquisition Corp [Member] | Private Placement Warrant Holders
Fair Value Disclosures [Line Items]
Number of warrants agreed to forfeit subject to closer of proposed business combination | shares		583,333			583,333
Number of potential warrants agreed to forfeit subject to closer of proposed business combination | shares		583,333			583,333
Warrants forfeiture period subject to closer of proposed business combination					54 months
ACON S2 Acquisition Corp [Member] | Maximum [Member] | Private Placement Warrant Holders
Fair Value Disclosures [Line Items]
Threshold common stock price target to potential forfeiture of warrants | $ / shares		$ 15			$ 15
Threshold common stock price target to forfeiture of warrants | $ / shares		15			15
ACON S2 Acquisition Corp [Member] | Minimum [Member] | Private Placement Warrant Holders
Fair Value Disclosures [Line Items]
Threshold common stock price target to potential forfeiture of warrants | $ / shares		12.50			12.50
Threshold common stock price target to forfeiture of warrants | $ / shares		$ 12.50			$ 12.50
ACON S2 Acquisition Corp [Member] | Expected Dividend Payment
Fair Value Disclosures [Line Items]
Alternative Investment, Measurement Input		0			0
ACON S2 Acquisition Corp [Member] | Derivative Liabilities
Fair Value Disclosures [Line Items]
Change in fair value of derivative warrant liabilities		$ 2,200,000			$ 1,100,000

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Assets and Liabilities Measured on Recurring Basis (Detail) - Fair Value, Recurring [Member] - USD ($)	Sep. 30, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash equivalents and restricted cash:
Money market funds	$ 6,986,000	$ 3,046,000
Certificate of deposit	75,000	326,000	$ 529,000
Total Assets	7,061,000	3,372,000	529,000
Liabilities:
Bridge loan	21,432
Derivative liabilities	248,450,000	22,911,000	11,379,000
Warrant liabilities		3,329,000	1,989,000
Total Liabilities	269,882,000	26,240,000	13,368,000
Level 1 [Member]
Cash equivalents and restricted cash:
Money market funds	6,986,000	3,046,000
Total Assets	6,986,000	3,046,000
Level 1 [Member] | ACON S2 Acquisition Corp [Member]
Cash equivalents and restricted cash:
Investments held in Trust Account	250,016,847	250,004,454
Level 1 [Member] | ACON S2 Acquisition Corp [Member] | Public Warrants [Member]
Liabilities:
Liabilities Fair Value Disclosure	10,333,330	13,625,000
Level 2 [Member]
Cash equivalents and restricted cash:
Certificate of deposit	75,000	326,000	529,000
Total Assets	75,000	326,000	529,000
Level 3 [Member]
Liabilities:
Bridge loan	21,432
Derivative liabilities	248,450,000	22,911,000	11,379,000
Warrant liabilities		3,329,000	1,989,000
Total Liabilities	269,882,000	26,240,000	$ 13,368,000
Level 3 [Member] | ACON S2 Acquisition Corp [Member] | Private Warrants [Member]
Liabilities:
Liabilities Fair Value Disclosure	9,883,720	$ 7,729,400
Level 3 [Member] | ACON S2 Acquisition Corp [Member] | Working Capital Loan Related Party [Member]
Liabilities:
Liabilities Fair Value Disclosure	$ 361,751

Fair Value Measurements - Sum_2

Fair Value Measurements - Summary of Changes in the Fair Value of the Level 3 Liabilities at Fair Value on a Recurring Basis (Detail) - Level 3 [Member] - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance			$ 26,240,000	$ 13,368,000	$ 13,368,000
Ending balance	$ 269,882,000	$ 7,485,000	269,882,000	7,485,000	26,240,000	$ 13,368,000
Total	269,882,000	7,485,000	269,882,000	7,485,000	26,240,000	13,368,000
Warrant Liabilities [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	22,860,000	1,979,000	3,329,000	1,989,000	1,989,000	1,648,000
Change in fair value	2,949,000	(24,000)	17,753,000	(78,000)	1,296,000	341,000
Fair value of warrants issued / exercised			5,096,000	44,000	44,000
Ending balance		1,955,000		1,955,000	3,329,000	1,989,000
Total		1,955,000		1,955,000	3,329,000	1,989,000
Warrant Liabilities [Member] | Warrants Exercised [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value of warrants issued / exercised	25,809,000		26,178,000
2018 Convertible Note Automatic Conversion Rights liability [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance						9,000
Change in fair value						19,000
Fair value of derivatives extinguished upon note conversion						(28,000)
Total
Series C-2 Convertible Preferers Stock Issuance Right Liability Member [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning balance	211,747,000	7,619,000	22,911,000	11,379,000	11,379,000
Change in fair value	36,703,000	(2,089,000)	248,691,000	(5,849,000)	11,532,000
Fair value of derivatives extinguished upon note conversion			(23,152,000)
Fair value of derivatives issued						11,379,000
Ending balance	248,450,000	5,530,000	248,450,000	5,530,000	22,911,000	11,379,000
Total	248,450,000	$ 5,530,000	248,450,000	$ 5,530,000	$ 22,911,000	$ 11,379,000
Bridge Loan [Members]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value of warrants issued / exercised	20,000		20,000
Fair value of derivatives extinguished upon note conversion	1,432		1,432
Ending balance	21,432		21,432
Total	$ 21,432		$ 21,432

Fair Value Measurements - Sum_3

Fair Value Measurements - Summary of Quantitative Information Regarding Level 3 Fair Value Measurements Inputs at Measurement Dates (Details) - ACON S2 Acquisition Corp [Member] - Level 3 [Member]	Dec. 31, 2020	Sep. 30, 2020	Sep. 21, 2020	Sep. 30, 2021	Dec. 31, 2020
Stock Price
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Alternative Investment, Measurement Input	10.08			9.97	10.08
Stock Price | Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Alternative Investment, Measurement Input		9.64	9.64
Stock Price | Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Alternative Investment, Measurement Input		9.42	9.42
Volatility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Alternative Investment, Measurement Input	10	10	10	42.2	10
Expected Life of the Options to Convert
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Alternative Investment, Measurement Term	5 years 10 months 24 days	6 years	6 years	5 years 7 days	5 years 10 months 24 days
Risk-free Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Alternative Investment, Measurement Input	0.48	0.37	0.37	0.98	0.48
Dividend yield
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Alternative Investment, Measurement Input	0	0	0	0	0
Probability of merger
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Alternative Investment, Measurement Input	100	100	100		100

Fair Value Measurements - Sum_4

Fair Value Measurements - Summary of Change in Level 3 Fair Value of Derivative Warrant Liabilities (Details) - USD ($)	Sep. 21, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Change in fair value of derivative warrant liabilities		$ 2,949,000	$ (24,000)			$ 17,753,000	$ (78,000)	$ 1,296,000	$ 341,000
ACON S2 Acquisition Corp [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Beginning balance of derivative warrant liabilities						21,354,400
Change in fair value of derivative warrant liabilities	$ 19,500,000	2,232,690		$ 1,854,400		(1,137,350)
Ending balance of Derivative warrant liabilities		20,217,050		21,354,400	$ 21,354,400	20,217,050		21,354,400
Level 3 [Member] | ACON S2 Acquisition Corp [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Beginning balance of derivative warrant liabilities						7,729,400
Issuance of Warrants					19,500,000
Change in fair value of derivative warrant liabilities					1,854,400	2,154,320
Transfer of Public Warrants to level 1					(13,625,000)
Ending balance of Derivative warrant liabilities		9,883,720		7,729,400	7,729,400	9,883,720		7,729,400
Level 3 [Member] | Working Capital Loan Related Party [Member] | ACON S2 Acquisition Corp [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Beginning balance of derivative warrant liabilities						0
Change in fair value of derivative warrant liabilities						0
Ending balance of Derivative warrant liabilities		$ 361,751		0	0	361,751		0
Initial fair value of working capital loan - related party						361,751
Level 3 [Member] | Public Warrants [Member] | ACON S2 Acquisition Corp [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Issuance of Warrants					12,500,000
Change in fair value of derivative warrant liabilities					1,125,000
Transfer of Public Warrants to level 1					(13,625,000)
Level 3 [Member] | Private Placement Warrants [Member] | ACON S2 Acquisition Corp [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Beginning balance of derivative warrant liabilities						$ 7,729,400
Issuance of Warrants					7,000,000
Change in fair value of derivative warrant liabilities					729,400
Ending balance of Derivative warrant liabilities				$ 7,729,400	$ 7,729,400			$ 7,729,400

Income Taxes - Summary Of Net D

Income Taxes - Summary Of Net Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred Tax Assets, Gross [Abstract]
Net operating losses	$ 11,566	$ 7,365
Tax credit carryforward	47	12
Other	837	513
Deferred tax assets	12,450	7,890
Valuation allowance	(12,450)	(7,890)
Deferred tax assets, net of valuation allowance	$ 0	$ 0

Income Taxes - Schedule of Reco

Income Taxes - Schedule of Reconciliation of U.S. Federal Statutory Income Tax Rate and Effective Income Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Tax computed at federal statutory rate	21.00%	21.00%
State tax, net of federal tax benefit	3.00%	4.40%
Stock compensation	(0.20%)	(0.20%)
Permanent differences	(8.90%)	(2.30%)
163(I) Interest	0.00%	(0.90%)
R&D tax credits	0.10%	0.10%
Other	0.00%	(0.10%)
Valuation allowance	(15.00%)	(22.00%)
Income tax expense (benefit)	0.00%	0.00%

Income Taxes - Summary Of Compa

Income Taxes - Summary Of Company's Uncertain Tax Positions (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Income Tax Uncertainties [Abstract]
Beginning balance	$ 12	$ 0
Additions	35	12
Ending balance	$ 47	$ 12

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Valuation allowance deferred tax asset increase decrease Amount	$ 4,560
Unrecognized tax benefits period increase decrease	35	$ 12
Unrecognized tax benefits, income tax penalties and interest accrued	$ 0	$ 0
Sections 382 and 383 [Member]
Cummualtive change In ownership percentage	50.00%
Research Tax Credit Carryforward [Member]
Tax credit carryforward amount	$ 94
Tax credit carry forwards expiration year	2039 years
Domestic Tax Authority [Member]
Net operating loss carryforwards	$ 44,121
State and Local Jurisdiction [Member]
Net operating loss carryforwards	44,121
Non Expirable [Member] | Domestic Tax Authority [Member]
Net operating loss carryforwards	$ 33,666
Expirable [Member]
Operating loss carry forwards expiration start year	2032 years
Operating loss carry forwards expiration end year	2027 years

Defined Contribution Plan - Add

Defined Contribution Plan - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Retirement Benefits [Abstract]
Company contributions under 401 (k) Plan	$ 173	$ 35

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Details) - USD ($)	Oct. 31, 2020	Sep. 21, 2020	Sep. 16, 2020	Jul. 27, 2020	Sep. 30, 2020	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2021	Dec. 31, 2020	Dec. 31, 2019
Related Party Transaction [Line Items]
Ordinary shares, issued						9,125,954	7,134,668	9,125,954	7,134,668	7,060,668
Consultants Fee [Member]
Related Party Transaction [Line Items]
Related Party Transaction, Amounts of Transaction									$ 31,000
Minimum [Member]
Related Party Transaction [Line Items]
Equity method investment ownership percentage							5.00%		5.00%
Investors [Member]
Related Party Transaction [Line Items]
Interest expense related party										$ 499,000
Investors [Member] | Conversion Of Accrued Interest To Equity [Member] | Convertible Debt [Member]
Related Party Transaction [Line Items]
Debt instrument converted converted instrument amount										$ 615,000
ACON S2 Acquisition Corp [Member]
Related Party Transaction [Line Items]
Aggregate expenses in issuance of ordinary shares to sponsor					$ 25,000		$ 25,000
Number of trading days in period							10 days	10 days
Debt face amount				$ 300,000
Note payable - related party						$ 361,751		$ 361,751
Warrants price per unit						$ 11.50	$ 11.50	$ 11.50	$ 11.50
Payment of earlier consummation to sponsor			$ 10,000
Expenses from transactions with related party						$ 30,000		$ 90,000
Accrued expenses for related party						130,000	$ 40,000	130,000	$ 40,000
ACON S2 Acquisition Corp [Member] | Initial Public Offering
Related Party Transaction [Line Items]
Aggregate expenses in issuance of ordinary shares to sponsor		$ 25,000,000
ACON S2 Acquisition Corp [Member] | Sponsor
Related Party Transaction [Line Items]
Accrued expenses for related party						130,000	40,000	130,000	40,000
ACON S2 Acquisition Corp [Member] | Sponsor | Working Capital Loans [Member]
Related Party Transaction [Line Items]
Warrants price per unit				$ 1.50
Borrowing outstanding		0		$ 0		$ 362,000	0	$ 362,000	$ 0
ACON S2 Acquisition Corp [Member] | Sponsor | Initial Public Offering | Promissory Note [Member]
Related Party Transaction [Line Items]
Aggregate expenses in issuance of ordinary shares to sponsor		25,000
Note payable - related party		$ 112,000		$ 112,000
ACON S2 Acquisition Corp [Member] | Sponsor | Founder Shares [Member]
Related Party Transaction [Line Items]
Minimum period for not to transfer, assign or sell of any shares				1 year
Closing price of ordinary shares				$ 12
Number of trading days period commencing after initial business combination				150 days
ACON S2 Acquisition Corp [Member] | Sponsor | Minimum [Member] | Founder Shares [Member]
Related Party Transaction [Line Items]
Number of trading days in period				20 days
ACON S2 Acquisition Corp [Member] | Sponsor | Maximum [Member] | Working Capital Loans [Member] | Warrants
Related Party Transaction [Line Items]
Debt instrument converted converted instrument amount				$ 1,500,000
ACON S2 Acquisition Corp [Member] | Sponsor | Maximum [Member] | Founder Shares [Member]
Related Party Transaction [Line Items]
Number of trading days in period				30 days
ACON S2 Acquisition Corp [Member] | Common Class B [Member]
Related Party Transaction [Line Items]
Aggregate expenses in issuance of ordinary shares to sponsor					$ 719		$ 719
Ordinary shares, issued						6,250,000	6,250,000	6,250,000	6,250,000
Common stock subject to forfeiture						937,500	937,500	937,500	937,500
Over-allotment expiration date							Oct. 31, 2020	Oct. 31, 2020
Common stock shares forfeited due to non-exercise of over-allotment option in full or part by underwriters	937,500						937,500	937,500
ACON S2 Acquisition Corp [Member] | Common Class B [Member] | Sponsor
Related Party Transaction [Line Items]
Aggregate expenses in issuance of ordinary shares to sponsor				$ 25,000
Ordinary shares, issued				7,187,500
Common stock subject to forfeiture				937,500
Percentage of founder shares representing issued and outstanding shares				20.00%
Over-allotment expiration date				Oct. 31, 2020

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) - USD ($)	Oct. 08, 2021	May 06, 2021	Mar. 31, 2021	Sep. 30, 2021	Dec. 31, 2019	May 07, 2021	Feb. 26, 2021	Jan. 01, 2021	Dec. 31, 2020
Subsequent Event [Line Items]
Additional lease term								5 years
Lease monthly base rent								$ 42,000
Percentage of annual increase of monthly base rent								3.00%
Common Stock, Shares Authorized				79,000,000	79,000,000	79,000,000			79,000,000
Common stock par value				$ 0.0001	$ 0.0001	$ 0.0001			$ 0.0001
Common stock, par or stated value per share				0.0001	$ 0.0001	$ 0.0001			$ 0.0001
Sale of Stock, Price Per Share				$ 10
Completion Of SPAC Merger [Member]
Subsequent Event [Line Items]
Sale of Stock, Consideration Received on Transaction				$ 16,001,437
Merger with ACON S2 Acquisition Corp [Member]
Subsequent Event [Line Items]
Business combination consideration transferred		$ 1,070,000,000
Cash Acquired from Acquisition		$ 465,000,000
Amendment to Series C Two and Series C Preferred Stock Purchase Agreement [Member]
Subsequent Event [Line Items]
Number of securities into which the class of warrant or right may be converted				14,365,207
Amendment to Series C Two and Series C Preferred Stock Purchase Agreement [Member] | Completion Of SPAC Merger [Member]
Subsequent Event [Line Items]
Proceeds receivable from issuance of redeemable convertible preferred stock and warrants						$ 16,000,000
Amendment to Series C Two and Series C Preferred Stock Purchase Agreement [Member] | Class C Two Warrants [Member] | Completion Of SPAC Merger [Member]
Subsequent Event [Line Items]
Number of securities into which the class of warrant or right may be converted						14,364,207
Class of warrant or right exercise price of warrants or rights						$ 0.0001
Redeemable Convertible Preferred Stock [Member]
Subsequent Event [Line Items]
Temporary Equity, Shares Authorized									61,436,037
Temporary equity stock issued during period value new issues					$ 18,396,000
Series A Redeemable Convertible Preferred Stock [Member]
Subsequent Event [Line Items]
Temporary Equity, Shares Authorized				5,941,109					5,941,109
Temporary equity issue price per share				$ 0.56					$ 0.56
Series B Redeemable Convertible Preferred Stock [Member]
Subsequent Event [Line Items]
Temporary Equity, Shares Authorized				12,011,923					12,011,923
Temporary equity issue price per share				$ 1.23					$ 1.22848
Series C One Redeemable Convertible Preferred Stock [Member]
Subsequent Event [Line Items]
Temporary Equity, Shares Authorized				16,345,688					16,345,688
Temporary equity issue price per share				$ 1.84					$ 1.84248
Series C Two Redeemable Convertible Preferred Stock [Member]
Subsequent Event [Line Items]
Common stock par value				$ 0.0001
Temporary Equity, Shares Authorized				27,773,344					27,137,317
Temporary equity stock shares Issued During The Period Shares			3,900,988
Temporary equity stock issued during period value new issues			$ 11,500
Number of securities into which the class of warrant or right may be converted			585,145
Class of warrant or right exercise price of warrants or rights			$ 0.0001
Temporary equity issue price per share			$ 2.94797	$ 2.95
Common stock, par or stated value per share				$ 0.0001
Series C Two Redeemable Convertible Preferred Stock [Member] | Amendment to Series C Two and Series C Preferred Stock Purchase Agreement [Member] | Completion Of SPAC Merger [Member]
Subsequent Event [Line Items]
Temporary Equity, Share Subscriptions						5,427,464
Series C Two Redeemable Convertible Preferred Stock [Member] | Series C Two Redeemable Convertible Preferred Stock Issuance Right [Member]
Subsequent Event [Line Items]
Temporary equity shares subscribed but not issued shares			23,236,327
Fourth Restatement Of Authorized Share Capital [Member]
Subsequent Event [Line Items]
Common Stock, Shares Authorized							79,000,000
Common stock par value							$ 0.0001
Common stock, par or stated value per share							$ 0.0001
Fourth Restatement Of Authorized Share Capital [Member] | Redeemable Convertible Preferred Stock [Member]
Subsequent Event [Line Items]
Temporary Equity, Shares Authorized							62,072,064
Fourth Restatement Of Authorized Share Capital Of The Company [Member] | Redeemable Convertible Preferred Stock [Member]
Subsequent Event [Line Items]
Temporary Equity, Par or Stated Value Per Share							$ 0.0001
Fourth Restatement Of Authorized Share Capital Of The Company [Member] | Series A Redeemable Convertible Preferred Stock [Member]
Subsequent Event [Line Items]
Temporary Equity, Shares Authorized							5,941,109
Fourth Restatement Of Authorized Share Capital Of The Company [Member] | Series B Redeemable Convertible Preferred Stock [Member]
Subsequent Event [Line Items]
Temporary Equity, Shares Authorized							12,011,923
Fourth Restatement Of Authorized Share Capital Of The Company [Member] | Series C One Redeemable Convertible Preferred Stock [Member]
Subsequent Event [Line Items]
Temporary Equity, Shares Authorized							16,345,688
Fourth Restatement Of Authorized Share Capital Of The Company [Member] | Series C Two Redeemable Convertible Preferred Stock [Member]
Subsequent Event [Line Items]
Temporary Equity, Shares Authorized							27,773,344
Subsequent Event [Member]
Subsequent Event [Line Items]
Intial lease term								5 years
Repayments of debt	$ 20,000
Subsequent Event [Member] | ACON S2 Acquisition Corp [Member] | Merger Agreement [Member]
Subsequent Event [Line Items]
Common stock par value	$ 0.0001
Proceeds from Sales of Business, Affiliate and Productive Assets	$ 246,000
Common stock, par or stated value per share	$ 0.0001
Business Acquisition, Share Price	$ 1.47
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares	99,562,793
Subsequent Event [Member] | ACON S2 Acquisition Corp [Member] | Merger Agreement [Member] | Restricted Stock Units (RSUs) [Member]
Subsequent Event [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	824,998
Subsequent Event [Member] | New ESS Common Stock [Member] | ACON S2 Acquisition Corp [Member] | Merger Agreement [Member]
Subsequent Event [Line Items]
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares	16,500,000
Sale of Stock, Number of Shares Issued in Transaction	25,000,000
Sale of Stock, Price Per Share	$ 10
Sale of Stock, Consideration Received on Transaction	$ 250,000,000

Restatement of Financial Sta_12

Restatement of Financial Statements - Effect of Financial Statement Adjustments Related to Restatement on Statement of Changes in Shareholders' Equity (Details) - ACON S2 Acquisition Corp [Member] - USD ($)	2 Months Ended	5 Months Ended
	Sep. 30, 2020	Dec. 31, 2020
Remeasurement adjustment on Class A ordinary shares subject to possible redemption	$ (26,146,471)	$ 26,146,752
Previously Reported [Member]
Sale of units in initial public offering, gross	237,500,000	237,500,000
Offering costs	13,646,752	$ 13,646,752
Remeasurement adjustment on Class A ordinary shares subject to possible redemption	$ 0
Shares subject to possible redemption	(218,124,750)	(215,583,980)
Revision of Prior Period, Adjustment [Member]
Sale of units in initial public offering, gross	$ (237,500,000)	$ (237,500,000)
Offering costs	13,646,752	13,646,752
Remeasurement adjustment on Class A ordinary shares subject to possible redemption	$ (26,146,471)	$ (26,146,471)
Shares subject to possible redemption	218,124,750	215,583,980
As Restated [Member]
Sale of units in initial public offering, gross	$ 0	$ 0
Offering costs	$ 0	0
Remeasurement adjustment on Class A ordinary shares subject to possible redemption		$ (26,146,471)

Restatement of Financial Sta_13

Restatement of Financial Statements - Schedule of Unaudited Quarterly Financial Information for Restatement Statement of Changes in Shareholders' Equity (Details) - ACON S2 Acquisition Corp [Member] - USD ($)	2 Months Ended	5 Months Ended
	Sep. 30, 2020	Dec. 31, 2020
Remeasurement adjustment on Class A ordinary shares subject to possible redemption	$ (26,146,471)	$ 26,146,752
Previously Reported [Member]
Sale of units in initial public offering, gross	237,500,000	237,500,000
Offering costs	13,646,752	$ 13,646,752
Remeasurement adjustment on Class A ordinary shares subject to possible redemption	$ 0
Temporary equity, shares outstanding	218,124,750	215,583,980
Revision of Prior Period, Adjustment [Member]
Sale of units in initial public offering, gross	$ (237,500,000)	$ (237,500,000)
Offering costs	13,646,752	13,646,752
Remeasurement adjustment on Class A ordinary shares subject to possible redemption	$ (26,146,471)	$ (26,146,471)
Temporary equity, shares outstanding	(218,124,750)	(215,583,980)