SES AI (SES) 10-Q 7 Nov 23 2023 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - $ / shares	9 Months Ended
	Sep. 30, 2023	Oct. 31, 2023
Document Information [Line Items]
Entity Central Index Key	0001819142
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2023
Document Transition Report	false
Entity File Number	001-39845
Entity Registrant Name	SES AI Corporation
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	88-0641865
Entity Address, Address Line One	35 Cabot Road
Entity Address, City or Town	Woburn
Entity Address State Or Province	MA
Entity Address, Postal Zip Code	01801
City Area Code	339
Local Phone Number	298-8750
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3
Amendment Flag	false
Common Class A [Member]
Document Information [Line Items]
Title of 12(b) Security	Class A common stock, par value $0.0001 per share
Entity Listing, Par Value Per Share	$ 0.0001
Trading Symbol	SES
Security Exchange Name	NYSE
Entity Common Stock, Shares Outstanding		307,848,121
Common Class B [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		43,881,251
Warrant [Member]
Document Information [Line Items]
Title of 12(b) Security	Warrants, each exercisable for one share of Class A common stock at an exercise price of $11.50 per share
Trading Symbol	SES WS
Security Exchange Name	NYSE

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Current Assets
Cash and cash equivalents	$ 49,938	$ 106,623
Short-term investments	292,225	283,460
Receivable from related party	$ 2,481	$ 2,383
Other receivable, after allowance for credit loss, current, related party, type extensible enumeration	Related Party [Member]	Related Party [Member]
Inventories	$ 596	$ 383
Prepaid expenses and other current assets	6,877	3,792
Total current assets	352,117	396,641
Property and equipment, net	34,995	27,756
Intangible assets, net	1,377	1,473
Right-of-use assets, net	11,341	11,363
Other assets	3,423	3,206
Total assets	403,253	440,439
Current Liabilities
Accounts payable	5,820	6,187
Operating lease liabilities, current	2,144	1,899
Accrued expenses and other current liabilities	7,837	11,271
Total current liabilities	15,801	19,357
Sponsor Earn-Out Liability	5,549	10,961
Operating lease liabilities, non-current	9,534	10,165
Unearned government grant	6,209	6,657
Other liabilities	2,437	1,760
Total liabilities	39,530	48,900
Commitments and contingencies (Note 9)
Stockholders' Equity
Common stock: Class A shares, $0.0001 par value, 2,100,000,000 shares authorized; 307,839,557 and 305,833,589 shares issued and outstanding as of September 30, 2023 and December 31, 2022, respectively; Class B shares, $0.0001 par value, 200,000,000 shares authorized; 43,881,251 shares issued and outstanding as of September 30, 2023 and December 31, 2022	35	35
Additional paid-in capital	554,403	538,041
Accumulated deficit	(187,933)	(145,286)
Accumulated other comprehensive loss	(2,782)	(1,251)
Total stockholders' equity	363,723	391,539
Total liabilities stockholders' equity	$ 403,253	$ 440,439

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2023	Dec. 31, 2022
Common Class A [Member]
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	2,100,000,000	2,100,000,000
Common stock, shares issued (in shares)	307,839,557	305,833,589
Common stock, shares outstanding (in shares)	307,839,557	305,833,589
Common Class B [Member]
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Common stock, shares issued (in shares)	43,881,251	43,881,251
Common stock, shares outstanding (in shares)	43,881,251	43,881,251

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Operating expenses:
Research and development	$ 8,472	$ 8,421	$ 23,308	$ 19,680
General and administrative	10,885	13,308	36,932	40,305
Total operating expenses	19,357	21,729	60,240	59,985
Loss from operations	(19,357)	(21,729)	(60,240)	(59,985)
Other income (expense):
Interest income, net	4,197	1,972	12,466	2,460
Gain (loss) on change in fair value of Sponsor Earn-Out Liability, net	1,917	(4,870)	5,412	16,400
Other income (expense), net	(22)	420	393	(911)
Total other income (expense), net	6,092	(2,478)	18,271	17,949
Loss before income taxes	(13,265)	(24,207)	(41,969)	(42,036)
Provision for income taxes	(208)	(121)	(678)	(310)
Net loss	(13,473)	(24,328)	(42,647)	(42,346)
Other comprehensive (loss) income:
Unrealized gain (loss) on investments	242		(12)
Foreign currency translation adjustment	(99)	(1,194)	(1,519)	(2,462)
Total comprehensive loss	$ (13,330)	$ (25,522)	$ (44,178)	$ (44,808)
Net loss per share attributable to common stockholders - basic (in dollars per share)	$ (0.04)	$ (0.08)	$ (0.14)	$ (0.15)
Net loss per share attributable to common stockholders - diluted (in dollars per share)	$ (0.04)	$ (0.08)	$ (0.14)	$ (0.15)
Weighted-average common shares outstanding, basic (in shares)	315,627,263	311,680,656	314,550,810	280,859,250
Weighted-average common shares outstanding, diluted (in shares)	315,627,263	311,680,656	314,550,810	280,859,250

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity - USD ($) $ in Thousands		Common Stock [Member] Previously Reported [Member]	Common Stock [Member] Revision of Prior Period, Adjustment [Member]	[1]	Common Stock [Member]	Additional Paid-in Capital [Member] Previously Reported [Member]	Additional Paid-in Capital [Member] Revision of Prior Period, Adjustment [Member]	[1]	Additional Paid-in Capital [Member]	Retained Earnings [Member] Previously Reported [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member] Previously Reported [Member]	AOCI Attributable to Parent [Member]	Previously Reported [Member]	Revision of Prior Period, Adjustment [Member]	[1]	Total
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Redeemable convertible preferred stock, shares issued (in shares)														36,064,095	177,896,191		213,960,286
Redeemable convertible preferred stock, carrying amount														$ 269,941			$ 269,941
Beginning balance at Dec. 31, 2021			$ 6		$ 6	$ 5,604	$ (6)		$ 5,598	$ (94,293)	$ (94,293)	$ 367	$ 367	(88,322)			(88,322)
Beginning balance (in shares) at Dec. 31, 2021		10,474,509	51,668,426		62,142,935
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of redeemable convertible preferred stock to common stock in connection with reverse recapitalization upon Business Combination																	$ (269,941)
Conversion of redeemable convertible preferred stock to common stock in connection with reverse recapitalization upon Business Combination (in shares)																	(213,960,286)
Conversion of redeemable convertible preferred stock to common stock in connection with reverse recapitalization upon Business Combination					$ 21				269,920								$ 269,941
Conversion of redeemable convertible preferred stock to common stock in connection with reverse recapitalization upon Business Combination (in shares)					213,960,286
Business Combination and PIPE Financing, net of redemptions and transaction costs	[2]				$ 7				234,514								234,521
Business Combination and PIPE Financing, net of redemptions and transaction costs (in shares)	[2]				71,767,824
Forfeitures of Earn-Out restricted shares					(9,080)
Issuance of common stock upon exercise of stock options									4								4
Issuance of common stock upon exercise of stock options (in shares)					31,217
Stock-based compensation									3,186								3,186
Net Income (Loss)											(27,033)						(27,033)
Foreign currency translation adjustments													109				109
Ending balance at Mar. 31, 2022					$ 34				513,222		(121,326)		476				392,406
Ending balance (in shares) at Mar. 31, 2022					347,893,182
Beginning balance at Dec. 31, 2021			$ 6		$ 6	$ 5,604	$ (6)		5,598	$ (94,293)	(94,293)	$ 367	367	$ (88,322)			(88,322)
Beginning balance (in shares) at Dec. 31, 2021		10,474,509	51,668,426		62,142,935
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss)																	(42,346)
Foreign currency translation adjustments																	(2,462)
Ending balance at Sep. 30, 2022					$ 34				532,413		(136,639)		(2,095)				393,713
Ending balance (in shares) at Sep. 30, 2022					349,772,538
Beginning balance at Mar. 31, 2022					$ 34				513,222		(121,326)		476				392,406
Beginning balance (in shares) at Mar. 31, 2022					347,893,182
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Release of accrued transaction costs related to Business Combination and PIPE Financing									6,174								6,174
Issuance of common stock upon exercise of stock options									38								38
Issuance of common stock upon exercise of stock options (in shares)					337,453
Stock-based compensation									5,547								5,547
Net Income (Loss)											9,015						9,015
Foreign currency translation adjustments													(1,377)				(1,377)
Ending balance at Jun. 30, 2022					$ 34				524,981		(112,311)		(901)				411,803
Ending balance (in shares) at Jun. 30, 2022					348,230,635
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options									218								218
Issuance of common stock upon exercise of stock options (in shares)					1,376,206
Stock-based compensation									7,214								7,214
Restricted stock units vested (in shares)					165,697
Net Income (Loss)											(24,328)						(24,328)
Foreign currency translation adjustments													(1,194)				(1,194)
Ending balance at Sep. 30, 2022					$ 34				532,413		(136,639)		(2,095)				393,713
Ending balance (in shares) at Sep. 30, 2022					349,772,538
Beginning balance at Dec. 31, 2022					$ 35				538,041		(145,286)		(1,251)				391,539
Beginning balance (in shares) at Dec. 31, 2022					349,714,840
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Forfeitures of Earn-Out restricted shares					(1,904)
Issuance of common stock upon exercise of stock options									13								13
Issuance of common stock upon exercise of stock options (in shares)					94,319
Stock-based compensation									6,462								6,462
Restricted stock units vested (in shares)					4,727
Net Income (Loss)											(16,226)						(16,226)
Unrealized gain (loss) on investments													467				467
Foreign currency translation adjustments													72				72
Ending balance at Mar. 31, 2023					$ 35				544,516		(161,512)		(712)				382,327
Ending balance (in shares) at Mar. 31, 2023					349,811,982
Beginning balance at Dec. 31, 2022					$ 35				538,041		(145,286)		(1,251)				391,539
Beginning balance (in shares) at Dec. 31, 2022					349,714,840
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss)																	(42,647)
Unrealized gain (loss) on investments																	(12)
Foreign currency translation adjustments																	(1,519)
Ending balance at Sep. 30, 2023					$ 35				554,403		(187,933)		(2,782)				363,723
Ending balance (in shares) at Sep. 30, 2023					351,720,808
Beginning balance at Mar. 31, 2023					$ 35				544,516		(161,512)		(712)				382,327
Beginning balance (in shares) at Mar. 31, 2023					349,811,982
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Forfeitures of Earn-Out restricted shares					(237)
Issuance of common stock upon exercise of stock options									64								64
Issuance of common stock upon exercise of stock options (in shares)					477,443
Stock-based compensation									7,325								7,325
Restricted stock units vested (in shares)					924,179
Forfeitures of Restricted Stock Awards (in shares)					(1,431)
Net Income (Loss)											(12,948)						(12,948)
Unrealized gain (loss) on investments													(721)				(721)
Foreign currency translation adjustments													(1,492)				(1,492)
Ending balance at Jun. 30, 2023					$ 35				551,905		(174,460)		(2,925)				374,555
Ending balance (in shares) at Jun. 30, 2023					351,211,936
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Forfeitures of Earn-Out restricted shares					(306,526)
Issuance of common stock upon exercise of stock options									80								80
Issuance of common stock upon exercise of stock options (in shares)					715,939
Stock-based compensation									2,418								2,418
Restricted stock units vested (in shares)					103,167
Forfeitures of Restricted Stock Awards (in shares)					(3,708)
Net Income (Loss)											(13,473)						(13,473)
Unrealized gain (loss) on investments													242				242
Foreign currency translation adjustments													(99)				(99)
Ending balance at Sep. 30, 2023					$ 35				$ 554,403		$ (187,933)		$ (2,782)				$ 363,723
Ending balance (in shares) at Sep. 30, 2023					351,720,808
[1] Nine Month Period Ended September 30, 2022 Includes issuance of 33,793,878 restricted shares of Class A common stock and 3,999,796 restricted shares of Class B common stock, subject to vesting.

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity (Parenthetical)	9 Months Ended
	Sep. 30, 2022 shares
Common Stock [Member]
Common stock, shares issued (in shares)	349,772,538
Common Stock [Member] | Common Class A [Member]
Business Combination and PIPE Financing, net of redemptions and transaction costs, restricted shares subject to vesting (in shares)	33,793,878
Common Stock [Member] | Common Class B [Member]
Business Combination and PIPE Financing, net of redemptions and transaction costs, restricted shares subject to vesting (in shares)	3,999,796

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Cash Flows From Operating Activities
Net loss	$ (42,647)	$ (42,346)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	16,205	15,947
Accretion income from marketable securities	(8,608)
Depreciation and amortization	3,928	1,580
Gain from change in fair value of Sponsor Earn-Out liability	(5,412)	(16,400)
Other	(511)	(371)
Changes in operating assets and liabilities:
Receivable from related party	(98)	5,943
Inventories	(243)
Prepaid expenses and other assets	(3,336)	(3,401)
Accounts payable	625	(761)
Accrued expenses and other liabilities	(3,797)	2,002
Net cash used in operating activities	(43,894)	(37,807)
Cash Flows From Investing Activities
Purchases of property and equipment	(12,281)	(10,645)
Purchase of marketable securities	(180,051)
Maturities of marketable securities	180,000
Net cash used in investing activities	(12,332)	(10,645)
Cash Flows From Financing Activities
Proceeds from Business Combination and PIPE Financing, net of issuance costs		282,940
Proceeds from stock option exercises	157	260
Net cash provided by financing activities	157	283,200
Effect of exchange rates on cash	(664)	(639)
Net (decrease) increase in cash, cash equivalents and restricted cash	(56,732)	234,109
Cash, cash equivalents and restricted cash at beginning of period (Note 4)	107,936	161,044
Cash, cash equivalents and restricted cash at end of period (Note 4)	51,204	395,153
Supplemental Non-Cash Information:
Accounts payable and accrued expenses related to purchases of property and equipment	4,384	4,668
Lease liabilities arising from obtaining right-of-use assets	$ 1,751	1,565
Conversion of Redeemable Convertible Preferred Stock to shares of Class A Common Stock		(269,941)
Release of accrued transaction costs related to Business Combination and PIPE Financing		6,174
Liabilities acquired in the Business Combination		$ (387)

Nature of Business

Nature of Business	9 Months Ended
	Sep. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Business	Note 1. Nature of Business Organization SES AI Corporation and its consolidated subsidiaries (together the “Company” or “SES”), is engaged in the development of high-performance, Lithium-Metal (“Li-Metal”) rechargeable battery technologies for electric vehicles (“EVs”), Urban Air Mobility (“UAM”) and other applications. We were founded in 2012 and our mission is to facilitate the widespread adoption of sustainable electric transportation, both on land and in air, by creating best-in-class, high energy density Li-Metal batteries centered around long-range performance and safety. Our differentiated battery technology has been designed to combine the high energy density of Li-Metal with large-scale manufacturability of conventional Lithium-ion (“Li-ion”) batteries and will help to promote the transition from the global dependence on fossil fuel-based automotive vehicles to clean and efficient EVs. The Company’s headquarters are located in Woburn, Massachusetts with research and development facilities located there, in Shanghai, China, and in Chungju, South Korea. Principal operations have not yet commenced as of September 30, 2023, and the Company has not derived revenue from its principal business activities.

Basis of Presentation and Summa

Basis of Presentation and Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2023
Accounting Policies [Abstract]
Basis of Presentation and Summary of Significant Accounting Policies	Note 2. Basis of Presentation and Summary of Significant Accounting Policies Basis of Presentation The accompanying condensed consolidated financial statements include the accounts of the Company and have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) and regulations of the U.S. Securities and Exchange Commission (“SEC”) for interim financial reporting and are unaudited The results of operations for the three and nine months ended September 30, 2023 are not necessarily indicative of the results that may be expected for the full year or any other future interim or annual periods. As a result of the Business Combination completed on February 3, 2022, prior period share and per share amounts presented in the accompanying condensed consolidated financial statements and these related notes have been retroactively converted. The Company’s fiscal year ends on December 31. The year-end balance sheet data was derived from audited consolidated financial statements. These unaudited financial statements do not include all of the annual disclosures required by U.S. GAAP; accordingly, they should be read in conjunction with the audited consolidated financial statements and accompanying notes as of and for the year ended December 31 , 2022 included in the Company’s Annual Report on Form 10-K filed with the SEC on March 16, 2023 (the “Annual Report”). Use of estimates The preparation of these condensed consolidated financial statements in conformity with U.S. GAAP requires management to make use of estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of commitments and contingencies, and the reported amounts of revenues, if any, and expenses. The Company bases its estimates on available historical experience and on various other factors that the Company believes are reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not apparent from other sources. Changes in estimates are reflected in reported results for the period in which they become known. Actual results may differ from those estimates. Significant estimates and assumptions include those related to the valuation of (i) certain equity awards, including common stock awards prior to the Business Combination, the Sponsor Earn-Out Shares, the Earn-Out Restricted Shares, restricted stock awards, and performance stock units, (ii) deferred tax assets and uncertain income tax positions, and (iii) and the measurement of operating lease liabilities. On an ongoing basis, the Company evaluates these judgments and estimates for reasonableness. Investments The Company has investments in marketable debt and marketable equity securities. Investments in marketable debt securities, which are comprised of U.S. treasury securities, are classified as available-for-sale and are recorded at fair value with any unrealized gains and losses included as a component of accumulated other comprehensive loss in total stockholders’ equity on the consolidated balance sheets until realized or until a determination is made that an other-than-temporary decline in market value has occurred. The amortized cost of debt securities is adjusted for amortization of premiums and accretion of discounts to maturity, with such amortization and accretion reported within interest income, net in the consolidated statement of operations and comprehensive loss. Investments in marketable debt securities with a stated maturity date of less than one year are classified as short-term investments, while those with a stated maturity date of more than one year, and that are not expected to be used in current operations, are classified as long-term investments on the consolidated balance sheet, respectively. Investments in marketable equity securities with a readily determinable fair value, not accounted for under the equity method, are recorded at fair value with changes to fair value reported within other comprehensive (loss) income in the consolidated statements of operations and comprehensive loss. Fair Value Measurements Fair value is defined as an exchange price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. When determining the fair value measurements for assets and liabilities required or permitted to be either recorded or disclosed at fair value, the Company considers the principal or most advantageous market in which it would transact, and it also considers assumptions that market participants would use when pricing the asset or liability. The Company maximizes the use of observable inputs and minimizes the use of unobservable inputs when measuring fair value. GAAP establishes a fair value hierarchy based on the level of independent, objective evidence surrounding the inputs used to measure fair value. A financial instrument’s categorization within the fair value hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The fair value hierarchy is as follows: Level 1 Observable inputs such as quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date. Level 2 Inputs other than the quoted prices in active markets that are observable either directly or indirectly. Level 3 Unobservable inputs in which there are little or no market data and which require the Company to develop its own assumptions. Certain of the Company’s financial instruments, including cash and cash equivalents, accounts payable, accrued expenses and other current liabilities are carried at cost, which approximates their fair value because of their short-term nature. The following table presents information about the Company’s financial assets and liabilities that are measured at fair value on a recurring basis: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) Level 1 Level 2 Level 3 Total September 30, 2023 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Current assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents in money market funds (Note 4) $ 42,518 ​ $ — ​ $ — ​ $ 42,518 U.S. treasury securities (1) ​ 291,631 ​ ​ — ​ ​ — ​ ​ 291,631 Equity securities (2) ​ 594 ​ ​ — ​ ​ — ​ ​ 594 Total current assets at fair value $ 334,743 ​ $ — ​ $ — ​ $ 334,743 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Non-current assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. treasury securities (1) $ — ​ $ — ​ $ — ​ $ — Restricted cash in money market funds ​ 614 ​ ​ — ​ ​ — ​ ​ 614 Total non-current assets at fair value $ 614 ​ $ — ​ $ — ​ $ 614 Total assets at fair value $ 335,357 ​ $ — ​ $ — ​ $ 335,357 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Sponsor Earn-Out Liability (3) $ — ​ $ — ​ $ 5,549 ​ $ 5,549 Total liabilities at fair value $ — ​ $ — ​ $ 5,549 ​ $ 5,549 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Current assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents in money market funds (Note 4) $ 46,308 ​ $ — ​ $ — ​ $ 46,308 U.S. treasury securities (1) ​ 283,460 ​ ​ — ​ ​ — ​ ​ 283,460 Total current assets at fair value $ 329,768 ​ $ — ​ $ — ​ $ 329,768 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Non-current assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Restricted cash in money market funds $ 614 ​ $ — ​ $ — ​ $ 614 Total non-current assets at fair value $ 614 ​ $ — ​ $ — ​ $ 614 Total assets at fair value $ 330,382 ​ $ — ​ $ — ​ $ 330,382 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Sponsor Earn-Out Liability (3) $ — ​ $ — ​ $ 10,961 ​ $ 10,961 Total liabilities at fair value $ — ​ $ — ​ $ 10,961 ​ $ 10,961 (1) (2) (3) ​ There were no transfers in or out of Level 3 measurements during the three and nine months ended September 30, 2023. Recently Adopted Accounting Pronouncements The Company has reviewed all accounting pronouncements issued during the three months ended September 30, 2023 and concluded they were either not applicable or not expected to have a material impact on the Company’s condensed consolidated financial statements.

Partnerships

Partnerships	9 Months Ended
	Sep. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Partnerships	In December 2020, the Company established a partnership with Hyundai Motor Company (“Hyundai”) when it entered into a joint development agreement (“JDA”) to jointly research and develop Li-Metal battery technology. Further, in May 2021, the Company executed another JDA with Hyundai to jointly develop an A-Sample Li-Metal battery effective August 31, 2021. The JDAs have an initial term of three years. In February 2021, the Company established a partnership with GM Global Technology Operations LLC (“GM Technology”), an affiliate of GM Ventures LLC (“GM Ventures”), and General Motors Holdings LLC (“GM Holdings”) (collectively, “General Motors” or “GM”) when it entered into a JDA to jointly research and develop an A-Sample Li-Metal battery cell and build-out a prototype manufacturing line for GM Technology. The JDA has an initial term of three years. In December 2021, the Company established a partnership with Honda Motor Company, Ltd. (“Honda”) when it entered into a JDA to jointly research and develop an A-Sample Li-Metal battery cell. The JDA had a term of two years, which concluded on June 30, 2023. Under the terms of certain JDAs, the Company will fund research and development activities and capital expenditures related the buildout of pilot manufacturing lines and the JDA partner will be required to reimburse such expenses to the Company, regardless of the results of the research and development activities. The following table summarizes credits to research and development recorded in accordance to the terms of the JDA agreements: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, (in thousands) 2023 2022 ​ 2023 2022 Research and development (related party) $ 2,511 ​ $ 2,216 ​ $ 6,818 ​ $ 5,672 Research and development ​ 414 ​ ​ 1,045 ​ ​ 7,580 ​ ​ 3,443 Total credits to research and development $ 2,925 ​ $ 3,261 ​ $ 14,398 ​ $ 9,116 ​ Additionally, the Company recorded $0.5 million and $9.9 million as a credit to property and equipment in the condensed consolidated balance sheet for the three and nine months ended September 30, 2022, respectively, which represents reimbursements received from a related party for property and equipment constructed and owned by the Company. ​ As of September 30, 2023 and December 31, 2022, $2.5 million and $2.4 million, respectively, were outstanding as a receivable from related party as disclosed in the condensed consolidated balance sheets. As of September 30, 2023, there was a non-related party receivable of $0.5 million outstanding compared to no amount outstanding at December 31, 2022. As of September 30, 2023, there was no deferred income for non-related party JDAs as compared to the $4.2 million recorded as deferred income at December 31, 2022. Amounts for non-related party receivables and deferred income are recorded within prepaid expenses and other current assets and accrued expenses and other current liabilities, respectively, in the consolidated balance sheets .

Cash and Cash Equivalents

Cash and Cash Equivalents	9 Months Ended
	Sep. 30, 2023
Cash and Cash Equivalents [Abstract]
Cash and Cash Equivalents	Note 4. Cash and Cash Equivalents Cash, cash equivalents, and restricted cash consisted of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) September 30, 2023 December 31, 2022 Cash $ 7,420 ​ $ 60,315 Money market funds 42,518 ​ 46,308 Total cash and cash equivalents ​ 49,938 ​ ​ 106,623 Restricted cash included in other assets 1,266 ​ 1,313 Total cash, cash equivalents, and restricted cash shown in the condensed consolidated statements of cash flows $ 51,204 ​ $ 107,936 ​ ​ ​ Restricted cash includes cash held in checking and money market funds as collateral to secure certain insurance policies and a letter of credit for corporate lease activity.

Investments

Investments	9 Months Ended
	Sep. 30, 2023
Investments, Debt and Equity Securities [Abstract]
Investments	Note 5. Investments The following table provides amortized costs, gross unrealized gains and losses, and fair values for the Company’s investments in available-for-sale marketable debt securities as of September 30, 2023, which have maturity dates that range from 1 month to 9 months. There were no realized gains or losses for the three and nine months ended September 30, 2023. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2023 ​ ​ ​ Gross ​ Gross ​ ​ ​ (in thousands) Amortized Cost Unrealized Gains Unrealized Losses Fair Value Short-term U.S. treasury securities $ 291,888 ​ $ — ​ $ (257) ​ $ 291,631 Total $ 291,888 ​ $ — ​ $ (257) ​ $ 291,631 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 ​ ​ ​ Gross ​ Gross ​ ​ ​ (in thousands) Amortized Cost Unrealized Gains Unrealized Losses Fair Value Short-term U.S. treasury securities $ 283,705 ​ $ 2 ​ $ (247) ​ $ 283,460 Total $ 283,705 ​ $ 2 ​ $ (247) ​ $ 283,460

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	9 Months Ended
	Sep. 30, 2023
Payables and Accruals [Abstract]
Accrued Expenses and Other Current Liabilities	Note 6. Accrued Expenses and Other Current Liabilities The components of accrued expenses and other current liabilities consisted of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) September 30, 2023 December 31, 2022 Employee compensation and related costs $ 3,736 ​ $ 3,115 Construction in process ​ 1,674 ​ ​ 229 Income taxes payable ​ 1,075 ​ ​ 1,422 Professional and consulting services ​ 572 ​ ​ 1,566 Deferred income received under joint development agreements ​ — ​ ​ 4,189 Other 780 ​ 750 Accrued expenses and other current liabilities $ 7,837 ​ $ 11,271

Government Grant

Government Grant	9 Months Ended
	Sep. 30, 2023
Government Assistance [Abstract]
Government Grant	Note 7. Government Grant In December 2022, the Company was awarded a grant (the “Grant”) from certain government agencies. The incentives received under the Grant, which is in the form of cash, can be used for facilities related expenses and the purchase of property and equipment. The Company is required to adhere to certain conditions attached to the incentives, which include required minimum investments into specified spending categories and the creation of a minimum amount of permanent full-time jobs in a certain geographical location over the next five years. The Company has received, but not yet earned, 8.4 billion Korean won, which is equivalent to $6.2 million and $6.7 million, after translation, as of September 30, 2023 and December 31, 2022, respectively, which is disclosed as a noncurrent liability in the condensed consolidated balance sheet. ​

Sponsor Earn-Out Liability

Sponsor Earn-Out Liability	9 Months Ended
	Sep. 30, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Sponsor Earn-Out Liability	Note 8. Sponsor Earn-Out Liability Prior to the closing of the Business Combination (the “Closing”), Ivanhoe Capital Acquisition Corp. (“Ivanhoe”), a Cayman Islands exempted company, migrated out of the Cayman Islands and domesticated as a Delaware corporation (the “Domestication”) and changed its name to “SES AI Corporation.” On February 2, 2022, in connection with the Domestication, 6,900,000 of Ivanhoe’s Class B ordinary shares held by Ivanhoe Capital Sponsor LLC (the “Sponsor”) converted into an equal number of shares of duly authorized, validly issued, fully paid and nonassessable Class B common stock, par value $0.0001 per share (the “Class B Common Stock”), of the Company. At Closing, these 6,900,000 shares of Class B Common Stock converted into an equal number of shares of duly authorized, validly issued, fully paid and nonassessable Class A common stock par value $0.0001 per share (the “Class A Common Stock”, and together with the Class B Common Stock, “Common Stock”), of the Company . ● 20% were subject to transfer restrictions until the date that was 180 days after the Closing (“Tranche 1”); ● 20% are subject to transfer restrictions until SES’s closing stock price equals or exceeds $12.00 for 20 out of 30 consecutive trading days following the date that is 150 days after the Closing (“Tranche 2”); ● 20% are subject to transfer restrictions until SES’s closing stock price equals or exceeds $14.00 for 20 out of 30 consecutive trading days following the date that is 150 days after the Closing (“Tranche 3”); ● 20% are subject to transfer restrictions until SES’s closing stock price equals or exceeds $16.00 for 20 out of 30 consecutive trading days following the date that is 150 days after the Closing (“Tranche 4”); and ● 20% are subject to transfer restrictions until SES’s closing stock price equals or exceeds $18.00 for 20 out of 30 consecutive trading days following the date that is 150 days after the Closing (“Tranche 5”). If there is a change in control of SES at a per share value of greater than $18.00 , then 100% of the Sponsor Shares will be released from these transfer restrictions; however if the per share value is less than $18.00 upon a change in control, then the Sponsor Shares will be released pro rata based on the per share value of the change in control and the stock price thresholds for release specified above. Any Sponsor Shares not released will be forfeited and cancelled. The Sponsor Earn-Out Shares in Tranche 1 were accounted for as equity instruments because they are legally owned by the Sponsor, cannot be forfeited and were subject only to transfer restrictions that lapsed 180 days after the Closing Date, which occurred on August 2, 2022. The Sponsor Earn-Out Shares in Tranches 2 through 5 represent the Sponsor Earn-Out Liability and are accounted for as a derivative liability because the earn-out triggering events that determine the number of Sponsor Earn-Out Shares to be earned back by the Sponsor include events that are not solely indexed to the shares of Class A common stock. The Sponsor Earn-Out Liability is measured at its estimated fair value using Level 3 inputs in a Monte Carlo simulation valuation model. The following table provides a reconciliation of the beginning and ending fair value balances for the Sponsor Earn-Out Liability, which is recorded in the condensed consolidated balance sheet: ​ ​ ​ ​ ​ ​ (in thousands) Balance as of December 31, 2022 $ 10,961 Change in fair value (5,412) Balance as of September 30, 2023 $ 5,549 ​ Inherent in the valuation model are assumptions related to expected stock price volatility, risk-free interest rate, expected life, and dividend yield. The key inputs used in the Monte Carlo simulation model at their respective measurement dates were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2023 ​ ​ December 31, 2022 Contractual term (in years) ​ 3.3 ​ ​ 4.1 Risk free rate ​ 4.82% ​ ​ 4.09% Expected volatility ​ 84.0% ​ ​ 85.0% Expected dividends ​ 0% ​ ​ 0% Stock price $ 2.27 ​ $ 3.15 ​ The stock price is based on the closing price of the Company’s Class A common stock as of the valuation date and simulated through the end of the earn-out period following Geometric Brownian Motion. The Company estimates the volatility of its common stock by using an average of historical volatilities of SES’s and select peer companies’ common stock that matches the expected remaining term of the awards. The risk-free interest rate is based on the yield curve for zero-coupon U.S. Treasury notes with maturities corresponding to the expected remaining life of the awards, which is assumed to be equivalent to their remaining contractual term. The dividend rate is based on the historical rate, which the Company anticipates remaining at zero.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 9. Commitments and Contingencies Commitments Under the terms of one of the JDAs, the Company is committed to undertake certain research and development activities to the benefit of both itself and its OEM partner which involves expenditures related to engineering efforts and purchases of related equipment. This JDA has an agreed-upon value of up to $50 million, of which the Company has spent $8.7 million as of September 30, 2023. In December 2021, the Company amended the lease agreement on a facility in Woburn, Massachusetts. The amendment includes an obligation to pay monthly relinquishment charges (equal to the total rental obligation for the duration of the lease term), only if the new tenant does not pay monthly rental amount and lessor has provided a notice to collect the relinquishment charges from the Company. As of September 30, 2023, the Company assessed the probability of any liability to be incurred for relinquishment charges as remote. Legal Contingencies From time-to-time, the Company may be subject to claims arising in the ordinary course of business or become involved in litigation or other legal proceedings. While the outcome of such claims or other proceedings cannot be predicted with certainty, the Company’s management expects that any such liabilities, to the extent not provided for by insurance or otherwise, would not have a material effect on the Company’s financial condition, results of operations or cash flows. Indemnifications The Company enters into indemnification provisions under agreements with other companies in the ordinary course of business, including, but not limited to, partnerships, landlords, vendors, and contractors. Pursuant to these arrangements, the Company agrees to indemnify, defend, and hold harmless the indemnified party for certain losses suffered or incurred by the indemnified party as a result of the Company’s activities. The maximum potential amount of future payments the Company could be required to make under these agreements is not determinable. The Company has never incurred costs to defend lawsuits or settle claims related to these indemnification provisions. In addition, the Company indemnifies its officers, directors, and certain key employees against claims made with respect to matters that arise while they are serving in their respective capacities as such, subject to certain limitations set forth under applicable law, and applicable indemnification agreements. The Company maintains insurance, including commercial general liability insurance, product liability insurance, and directors and officers insurance to offset certain potential liabilities under these indemnification provisions. To date, there have been no claims under these indemnification provisions.

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2023
Share-Based Payment Arrangement [Abstract]
Stock-Based Compensation	Note 10. Stock-Based Compensation The Company’s stock-based compensation included in its condensed consolidated statements of operations and comprehensive income (loss), net of forfeitures, was as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, (in thousands) 2023 2022 2023 2022 Research and development $ (1,437) ​ $ 2,417 ​ $ 2,623 ​ $ 4,678 General and administrative 3,855 ​ 4,797 ​ 13,582 ​ 11,269 Total stock-based compensation $ 2,418 ​ $ 7,214 ​ $ 16,205 ​ $ 15,947 ​ The following table summarizes share-based compensation expense by award type: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, (in thousands) 2023 ​ 2022 ​ 2023 ​ 2022 Restricted Stock Units ("RSUs") $ 2,393 ​ $ 2,984 ​ $ 7,077 ​ $ 4,802 Earn-Out Restricted Shares ​ (1,597) ​ ​ 2,195 ​ ​ 2,704 ​ ​ 5,760 Performance Stock Units ("PSUs") ​ 739 ​ ​ 1,345 ​ ​ 3,471 ​ ​ 2,420 Restricted Stock Awards ("RSAs") ​ 782 ​ ​ 578 ​ ​ 2,638 ​ ​ 2,624 Stock options ​ 101 ​ ​ 112 ​ ​ 315 ​ ​ 341 Total $ 2,418 ​ $ 7,214 ​ $ 16,205 ​ $ 15,947 ​ In April 2023, the Company granted 4,071,979 RSUs and 1,631,800 PSUs, which relates to the annual grant to our directors, executive officers and employees. ​ ​ ​ ​ ​ ​ ​

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2023
Income Tax Disclosure [Abstract]
Income Taxes	Note 11. Income Taxes The Company’s effective tax rate for the three and nine months ended September 30, 2023 was (1.5)% and (1.4)%, respectively, compared with (0.5)% and (0.7)% for the three and nine months ended September 30, 2022. The difference between the provision for income taxes and the income tax determined by applying the statutory federal income tax rate of 21% principally results from income taxes on earnings from its foreign tax jurisdictions offset by losses generated in the U.S. where no benefit was recorded because the Company had fully reserved its deferred tax assets as of September 30, 2023 and December 31, 2022 and the recording of uncertain tax positions and interest expense. As of September 30, 2023, there were $0.9 million in changes to the total amount of unrecognized tax benefits related to transfer pricing adjustments from prior year end.

Net Income (Loss) Per Share

Net Income (Loss) Per Share	9 Months Ended
	Sep. 30, 2023
Earnings Per Share [Abstract]
Net Income (Loss) Per Share	Note 12. Net Income (Loss) Per Share Basic net income (loss) per share is computed by dividing net income (loss) by the weighted average number of common shares outstanding for the period. Diluted net income (loss) per share is computed by dividing net income (loss), as adjusted for changes in fair value recognized in earnings from equity contracts classified as liabilities, by the weighted average number of common shares outstanding and, when dilutive, common share equivalents from outstanding stock options and restricted stock units (using the treasury-stock method). The weighted-average number of common shares used in the computation of basic and diluted net income per share were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, (in thousands, except share and per share amounts) 2023 2022 2023 2022 Numerator: ​ ​ ​ ​ ​ ​ ​ Net loss attributable to common stockholders - basic $ (13,473) ​ $ (24,328) ​ $ (42,647) ​ $ (42,346) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Denominator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average shares of common stock outstanding - basic and diluted ​ 315,627,263 ​ 311,680,656 ​ 314,550,810 ​ 280,859,250 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net loss per share attributable to common stockholders - basic and diluted $ (0.04) ​ $ (0.08) ​ $ (0.14) ​ $ (0.15) ​ The number of common stock equivalents excluded from the computation of diluted net loss per share because either the effect would have been anti-dilutive, or the performance criteria related to such shares and awards had not been met, were as follows: ​ ​ ​ ​ ​ ​ ​ ​ As of September 30, ​ 2023 ​ 2022 Escrowed Earn-Out Shares ​ 27,690,978 ​ ​ 27,690,978 Options to purchase common stock ​ 16,032,057 ​ ​ 18,724,863 Public Warrants ​ 9,199,947 ​ ​ 9,199,947 Sponsor Earn-Out Shares ​ 5,520,000 ​ ​ 5,520,000 Private Warrants ​ 5,013,333 ​ ​ 5,013,333 Unvested RSUs ​ 6,350,199 ​ ​ 2,755,058 Unvested PSUs ​ 3,364,810 ​ ​ 2,116,942 Earn-Out Restricted Shares ​ 1,622,377 ​ ​ 1,952,336 Unvested RSAs ​ 753,038 ​ ​ 1,505,944 Total ​ 75,546,739 ​ ​ 74,479,401

Related-Party Transactions

Related-Party Transactions	9 Months Ended
	Sep. 30, 2023
Related Party Transactions [Abstract]
Related-Party Transactions	Note 13. Related-Party Transactions As of September 30, 2023 and December 31, 2022, pursuant to the Director Nomination Agreement, General Motors Company and its affiliates (“GM”) were considered related parties due to their board representation and the board member’s employment position at GM, which remained in effect as long as GM continues to hold more than 5% of the fully diluted outstanding equity securities of SES as per the agreement. See “Note 3 – Partnerships” for more details about our partnership with GM. ​

Basis of Presentation and Sum_2

Basis of Presentation and Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2023
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying condensed consolidated financial statements include the accounts of the Company and have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) and regulations of the U.S. Securities and Exchange Commission (“SEC”) for interim financial reporting and are unaudited The results of operations for the three and nine months ended September 30, 2023 are not necessarily indicative of the results that may be expected for the full year or any other future interim or annual periods. As a result of the Business Combination completed on February 3, 2022, prior period share and per share amounts presented in the accompanying condensed consolidated financial statements and these related notes have been retroactively converted. The Company’s fiscal year ends on December 31. The year-end balance sheet data was derived from audited consolidated financial statements. These unaudited financial statements do not include all of the annual disclosures required by U.S. GAAP; accordingly, they should be read in conjunction with the audited consolidated financial statements and accompanying notes as of and for the year ended December 31 , 2022 included in the Company’s Annual Report on Form 10-K filed with the SEC on March 16, 2023 (the “Annual Report”).
Use of Estimates	Use of estimates The preparation of these condensed consolidated financial statements in conformity with U.S. GAAP requires management to make use of estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of commitments and contingencies, and the reported amounts of revenues, if any, and expenses. The Company bases its estimates on available historical experience and on various other factors that the Company believes are reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not apparent from other sources. Changes in estimates are reflected in reported results for the period in which they become known. Actual results may differ from those estimates. Significant estimates and assumptions include those related to the valuation of (i) certain equity awards, including common stock awards prior to the Business Combination, the Sponsor Earn-Out Shares, the Earn-Out Restricted Shares, restricted stock awards, and performance stock units, (ii) deferred tax assets and uncertain income tax positions, and (iii) and the measurement of operating lease liabilities. On an ongoing basis, the Company evaluates these judgments and estimates for reasonableness.
Investments	Investments The Company has investments in marketable debt and marketable equity securities. Investments in marketable debt securities, which are comprised of U.S. treasury securities, are classified as available-for-sale and are recorded at fair value with any unrealized gains and losses included as a component of accumulated other comprehensive loss in total stockholders’ equity on the consolidated balance sheets until realized or until a determination is made that an other-than-temporary decline in market value has occurred. The amortized cost of debt securities is adjusted for amortization of premiums and accretion of discounts to maturity, with such amortization and accretion reported within interest income, net in the consolidated statement of operations and comprehensive loss. Investments in marketable debt securities with a stated maturity date of less than one year are classified as short-term investments, while those with a stated maturity date of more than one year, and that are not expected to be used in current operations, are classified as long-term investments on the consolidated balance sheet, respectively. Investments in marketable equity securities with a readily determinable fair value, not accounted for under the equity method, are recorded at fair value with changes to fair value reported within other comprehensive (loss) income in the consolidated statements of operations and comprehensive loss.
Fair Value Measurements	Fair Value Measurements Fair value is defined as an exchange price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. When determining the fair value measurements for assets and liabilities required or permitted to be either recorded or disclosed at fair value, the Company considers the principal or most advantageous market in which it would transact, and it also considers assumptions that market participants would use when pricing the asset or liability. The Company maximizes the use of observable inputs and minimizes the use of unobservable inputs when measuring fair value. GAAP establishes a fair value hierarchy based on the level of independent, objective evidence surrounding the inputs used to measure fair value. A financial instrument’s categorization within the fair value hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The fair value hierarchy is as follows: Level 1 Observable inputs such as quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date. Level 2 Inputs other than the quoted prices in active markets that are observable either directly or indirectly. Level 3 Unobservable inputs in which there are little or no market data and which require the Company to develop its own assumptions. Certain of the Company’s financial instruments, including cash and cash equivalents, accounts payable, accrued expenses and other current liabilities are carried at cost, which approximates their fair value because of their short-term nature. The following table presents information about the Company’s financial assets and liabilities that are measured at fair value on a recurring basis: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) Level 1 Level 2 Level 3 Total September 30, 2023 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Current assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents in money market funds (Note 4) $ 42,518 ​ $ — ​ $ — ​ $ 42,518 U.S. treasury securities (1) ​ 291,631 ​ ​ — ​ ​ — ​ ​ 291,631 Equity securities (2) ​ 594 ​ ​ — ​ ​ — ​ ​ 594 Total current assets at fair value $ 334,743 ​ $ — ​ $ — ​ $ 334,743 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Non-current assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. treasury securities (1) $ — ​ $ — ​ $ — ​ $ — Restricted cash in money market funds ​ 614 ​ ​ — ​ ​ — ​ ​ 614 Total non-current assets at fair value $ 614 ​ $ — ​ $ — ​ $ 614 Total assets at fair value $ 335,357 ​ $ — ​ $ — ​ $ 335,357 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Sponsor Earn-Out Liability (3) $ — ​ $ — ​ $ 5,549 ​ $ 5,549 Total liabilities at fair value $ — ​ $ — ​ $ 5,549 ​ $ 5,549 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Current assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents in money market funds (Note 4) $ 46,308 ​ $ — ​ $ — ​ $ 46,308 U.S. treasury securities (1) ​ 283,460 ​ ​ — ​ ​ — ​ ​ 283,460 Total current assets at fair value $ 329,768 ​ $ — ​ $ — ​ $ 329,768 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Non-current assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Restricted cash in money market funds $ 614 ​ $ — ​ $ — ​ $ 614 Total non-current assets at fair value $ 614 ​ $ — ​ $ — ​ $ 614 Total assets at fair value $ 330,382 ​ $ — ​ $ — ​ $ 330,382 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Sponsor Earn-Out Liability (3) $ — ​ $ — ​ $ 10,961 ​ $ 10,961 Total liabilities at fair value $ — ​ $ — ​ $ 10,961 ​ $ 10,961 (1) (2) (3) ​ There were no transfers in or out of Level 3 measurements during the three and nine months ended September 30, 2023.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements The Company has reviewed all accounting pronouncements issued during the three months ended September 30, 2023 and concluded they were either not applicable or not expected to have a material impact on the Company’s condensed consolidated financial statements.

Summary of Significant Accounti

Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2023
Accounting Policies [Abstract]
Schedule of financial assets and liabilities measured at fair value on a recurring basis	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) Level 1 Level 2 Level 3 Total September 30, 2023 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Current assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents in money market funds (Note 4) $ 42,518 ​ $ — ​ $ — ​ $ 42,518 U.S. treasury securities (1) ​ 291,631 ​ ​ — ​ ​ — ​ ​ 291,631 Equity securities (2) ​ 594 ​ ​ — ​ ​ — ​ ​ 594 Total current assets at fair value $ 334,743 ​ $ — ​ $ — ​ $ 334,743 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Non-current assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ U.S. treasury securities (1) $ — ​ $ — ​ $ — ​ $ — Restricted cash in money market funds ​ 614 ​ ​ — ​ ​ — ​ ​ 614 Total non-current assets at fair value $ 614 ​ $ — ​ $ — ​ $ 614 Total assets at fair value $ 335,357 ​ $ — ​ $ — ​ $ 335,357 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Sponsor Earn-Out Liability (3) $ — ​ $ — ​ $ 5,549 ​ $ 5,549 Total liabilities at fair value $ — ​ $ — ​ $ 5,549 ​ $ 5,549 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Current assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents in money market funds (Note 4) $ 46,308 ​ $ — ​ $ — ​ $ 46,308 U.S. treasury securities (1) ​ 283,460 ​ ​ — ​ ​ — ​ ​ 283,460 Total current assets at fair value $ 329,768 ​ $ — ​ $ — ​ $ 329,768 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Non-current assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Restricted cash in money market funds $ 614 ​ $ — ​ $ — ​ $ 614 Total non-current assets at fair value $ 614 ​ $ — ​ $ — ​ $ 614 Total assets at fair value $ 330,382 ​ $ — ​ $ — ​ $ 330,382 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Sponsor Earn-Out Liability (3) $ — ​ $ — ​ $ 10,961 ​ $ 10,961 Total liabilities at fair value $ — ​ $ — ​ $ 10,961 ​ $ 10,961 (1) (2) (3)

Partnerships (Tables)

Partnerships (Tables)	9 Months Ended
	Sep. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Summary of expenses incurred that were recorded as a credit to research and development expense in the consolidated statement of operations and comprehensive loss	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, (in thousands) 2023 2022 ​ 2023 2022 Research and development (related party) $ 2,511 ​ $ 2,216 ​ $ 6,818 ​ $ 5,672 Research and development ​ 414 ​ ​ 1,045 ​ ​ 7,580 ​ ​ 3,443 Total credits to research and development $ 2,925 ​ $ 3,261 ​ $ 14,398 ​ $ 9,116

Cash and Cash Equivalents (Tabl

Cash and Cash Equivalents (Tables)	9 Months Ended
	Sep. 30, 2023
Cash and Cash Equivalents [Abstract]
Schedule of cash, cash equivalents, and restricted cash	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) September 30, 2023 December 31, 2022 Cash $ 7,420 ​ $ 60,315 Money market funds 42,518 ​ 46,308 Total cash and cash equivalents ​ 49,938 ​ ​ 106,623 Restricted cash included in other assets 1,266 ​ 1,313 Total cash, cash equivalents, and restricted cash shown in the condensed consolidated statements of cash flows $ 51,204 ​ $ 107,936

Investments (Tables)

Investments (Tables)	9 Months Ended
	Sep. 30, 2023
Investments, Debt and Equity Securities [Abstract]
Schedule of amortized costs, gross unrealized gains and losses, and fair values of investments	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2023 ​ ​ ​ Gross ​ Gross ​ ​ ​ (in thousands) Amortized Cost Unrealized Gains Unrealized Losses Fair Value Short-term U.S. treasury securities $ 291,888 ​ $ — ​ $ (257) ​ $ 291,631 Total $ 291,888 ​ $ — ​ $ (257) ​ $ 291,631 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2022 ​ ​ ​ Gross ​ Gross ​ ​ ​ (in thousands) Amortized Cost Unrealized Gains Unrealized Losses Fair Value Short-term U.S. treasury securities $ 283,705 ​ $ 2 ​ $ (247) ​ $ 283,460 Total $ 283,705 ​ $ 2 ​ $ (247) ​ $ 283,460

Accrued Expenses and Other Cu_2

Accrued Expenses and Other Current Liabilities (Tables)	9 Months Ended
	Sep. 30, 2023
Payables and Accruals [Abstract]
Schedule of accrued expenses and other current liabilities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) September 30, 2023 December 31, 2022 Employee compensation and related costs $ 3,736 ​ $ 3,115 Construction in process ​ 1,674 ​ ​ 229 Income taxes payable ​ 1,075 ​ ​ 1,422 Professional and consulting services ​ 572 ​ ​ 1,566 Deferred income received under joint development agreements ​ — ​ ​ 4,189 Other 780 ​ 750 Accrued expenses and other current liabilities $ 7,837 ​ $ 11,271

Sponsor Earn-Out Liability (Tab

Sponsor Earn-Out Liability (Tables)	9 Months Ended
	Sep. 30, 2023
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of the reconciliation of the Sponsor Earn-Out liability	​ ​ ​ ​ ​ ​ (in thousands) Balance as of December 31, 2022 $ 10,961 Change in fair value (5,412) Balance as of September 30, 2023 $ 5,549
Schedule of key inputs into the Monte Carlo simulation model for the Sponsor Earn-Out liability	​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2023 ​ ​ December 31, 2022 Contractual term (in years) ​ 3.3 ​ ​ 4.1 Risk free rate ​ 4.82% ​ ​ 4.09% Expected volatility ​ 84.0% ​ ​ 85.0% Expected dividends ​ 0% ​ ​ 0% Stock price $ 2.27 ​ $ 3.15

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2023
Share-Based Payment Arrangement [Abstract]
Summary of compensation expense related to stock-based awards	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, (in thousands) 2023 2022 2023 2022 Research and development $ (1,437) ​ $ 2,417 ​ $ 2,623 ​ $ 4,678 General and administrative 3,855 ​ 4,797 ​ 13,582 ​ 11,269 Total stock-based compensation $ 2,418 ​ $ 7,214 ​ $ 16,205 ​ $ 15,947
Summary of share-based compensation expense by award type	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, (in thousands) 2023 ​ 2022 ​ 2023 ​ 2022 Restricted Stock Units ("RSUs") $ 2,393 ​ $ 2,984 ​ $ 7,077 ​ $ 4,802 Earn-Out Restricted Shares ​ (1,597) ​ ​ 2,195 ​ ​ 2,704 ​ ​ 5,760 Performance Stock Units ("PSUs") ​ 739 ​ ​ 1,345 ​ ​ 3,471 ​ ​ 2,420 Restricted Stock Awards ("RSAs") ​ 782 ​ ​ 578 ​ ​ 2,638 ​ ​ 2,624 Stock options ​ 101 ​ ​ 112 ​ ​ 315 ​ ​ 341 Total $ 2,418 ​ $ 7,214 ​ $ 16,205 ​ $ 15,947

Net Income (Loss) Per Share (Ta

Net Income (Loss) Per Share (Tables)	9 Months Ended
	Sep. 30, 2023
Earnings Per Share [Abstract]
Calculation of basic and diluted net loss per share	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended September 30, ​ Nine Months Ended September 30, (in thousands, except share and per share amounts) 2023 2022 2023 2022 Numerator: ​ ​ ​ ​ ​ ​ ​ Net loss attributable to common stockholders - basic $ (13,473) ​ $ (24,328) ​ $ (42,647) ​ $ (42,346) ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Denominator: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted average shares of common stock outstanding - basic and diluted ​ 315,627,263 ​ 311,680,656 ​ 314,550,810 ​ 280,859,250 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net loss per share attributable to common stockholders - basic and diluted $ (0.04) ​ $ (0.08) ​ $ (0.14) ​ $ (0.15)
Schedule of potentially dilutive securities	​ ​ ​ ​ ​ ​ ​ ​ As of September 30, ​ 2023 ​ 2022 Escrowed Earn-Out Shares ​ 27,690,978 ​ ​ 27,690,978 Options to purchase common stock ​ 16,032,057 ​ ​ 18,724,863 Public Warrants ​ 9,199,947 ​ ​ 9,199,947 Sponsor Earn-Out Shares ​ 5,520,000 ​ ​ 5,520,000 Private Warrants ​ 5,013,333 ​ ​ 5,013,333 Unvested RSUs ​ 6,350,199 ​ ​ 2,755,058 Unvested PSUs ​ 3,364,810 ​ ​ 2,116,942 Earn-Out Restricted Shares ​ 1,622,377 ​ ​ 1,952,336 Unvested RSAs ​ 753,038 ​ ​ 1,505,944 Total ​ 75,546,739 ​ ​ 74,479,401

Basis of Presentation and Signi

Basis of Presentation and Significant Accounting Policies - Fair Value - Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Assets, Fair Value Disclosure [Abstract]
Debt securities, available-for-sale, current	$ 292,225	$ 283,460
Restricted cash and cash equivalents, noncurrent	$ 1,266	$ 1,313
Financial Liabilities Fair Value Disclosure [Abstract]
Derivative Liability, Statement of Financial Position	Sponsor Earn-Out Liability	Sponsor Earn-Out Liability
Fair Value, Recurring [Member]
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents		$ 46,308
Debt securities, available-for-sale, current	$ 291,631	283,460
Equity securities	594
Total current assets at fair value	334,743	329,768
Total non-current assets at fair value	614	614
Assets	335,357	330,382
Financial Liabilities Fair Value Disclosure [Abstract]
Sponsor Earn-Out Liability	5,549	10,961
Total liabilities at fair value	5,549	10,961
Fair Value, Recurring [Member] | Money Market Funds [Member]
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents	42,518
Restricted cash and cash equivalents, noncurrent	614	614
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents		46,308
Debt securities, available-for-sale, current	291,631	283,460
Equity securities	594
Total current assets at fair value	334,743	329,768
Total non-current assets at fair value	614	614
Assets	335,357	330,382
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Money Market Funds [Member]
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents	42,518
Restricted cash and cash equivalents, noncurrent	614	614
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Financial Liabilities Fair Value Disclosure [Abstract]
Sponsor Earn-Out Liability	5,549	10,961
Total liabilities at fair value	$ 5,549	$ 10,961

Basis of Presentation and Sig_2

Basis of Presentation and Significant Accounting Policies - Fair Value - Transfers (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2023
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Transfers, Net [Abstract]
Fair value, measurement with unobservable inputs reconciliation, recurring basis, liability, transfers, net	$ 0	$ 0

Partnerships - General Informat

Partnerships - General Information (Details)	1 Months Ended
	Dec. 31, 2021	Aug. 31, 2021	Feb. 28, 2021
Hyundai Motor Company [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Joint development agreements, period		3 years
Director [Member] | GM Global Technology Operations LLC, Affiliate of General Motors Ventures LLC and General Motors Holdings LLC [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Joint development agreements, period			3 years
Investor [Member] | Honda Motor Company, Ltd. [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Joint development agreements, period	2 years

Partnerships - Credits to Resea

Partnerships - Credits to Research and Development (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Research and development (related party)	$ 2,511	$ 2,216	$ 6,818	$ 5,672
Research and development	414	1,045	7,580	3,443
Total credits to research and development	$ 2,925	$ 3,261	$ 14,398	$ 9,116

Partnerships - Credits to Prope

Partnerships - Credits to Property and Equipment (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Joint development agreements, research and development credit, related parties, reimbursements towards facility set-up costs	$ 0.5	$ 9.9

Partnerships - Receivables (Det

Partnerships - Receivables (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Related Party [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Other receivables	$ 2.5	$ 2.4
Nonrelated Party [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Other receivables	$ 0.5	$ 0

Partnerships - Deferred Income

Partnerships - Deferred Income (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Joint development agreements, deferred income	$ 0	$ 4.2

Cash and Cash Equivalents (Deta

Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Dec. 31, 2021
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash	$ 7,420	$ 60,315
Money market funds	42,518	46,308
Total cash and cash equivalents	49,938	106,623
Restricted cash included in other assets	1,266	1,313
Total cash, cash equivalents, and restricted cash shown in the condensed consolidated statements of cash flows	$ 51,204	$ 107,936	$ 395,153	$ 161,044
Restricted Cash and Cash Equivalents, Noncurrent, Statement of Financial Position	Other assets	Other assets

Investments - General Informati

Investments - General Information (Details) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2023 USD ($)	Sep. 30, 2023 USD ($)
Debt Securities, Available-for-Sale, Realized Gain (Loss) [Abstract]
Debt securities, available-for-sale, realized gain (loss)	$ 0	$ 0
Minimum [Member]
Debt Securities, Available-for-Sale [Abstract]
Debt securities, available-for-sale, term	1 month	1 month
Maximum [Member]
Debt Securities, Available-for-Sale [Abstract]
Debt securities, available-for-sale, term	9 months	9 months

Investments - Tabular Disclosur

Investments - Tabular Disclosure (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Debt Securities, Available-for-Sale, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Debt securities, available-for-sale, current	$ 292,225	$ 283,460
Amortized cost	291,888	283,705
Gross unrealized gains		2
Gross unrealized losses	(257)	(247)
Fair value	291,631	283,460
US Treasury and Government [Member]
Debt Securities, Available-for-Sale, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Amortized cost, current	291,888	283,705
Gross unrealized gains, current		2
Gross unrealized losses, current	(257)	(247)
Debt securities, available-for-sale, current	$ 291,631	$ 283,460

Accrued Expenses and Other Cu_3

Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Payables and Accruals [Abstract]
Employee compensation and related costs	$ 3,736	$ 3,115
Construction in process	1,674	229
Income taxes payable	1,075	1,422
Professional and consulting services	572	1,566
Deferred income received under joint development agreements		4,189
Other	780	750
Accrued expenses and other current liabilities	$ 7,837	$ 11,271

Government Grant (Details)

Government Grant (Details) $ in Millions, ₩ in Billions	1 Months Ended
	Dec. 31, 2022 KRW (₩)	Sep. 30, 2023 KRW (₩)	Sep. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)
Government Assistance [Abstract]
Government assistance, transaction duration	5 years
Government assistance, unearned government grant	₩ 8.4	₩ 8.4	$ 6.2	$ 6.7

Sponsor Earn-Out Liability - Ge

Sponsor Earn-Out Liability - General Information (Details)	Feb. 02, 2022 $ / shares shares
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Sponsor Earn-Out Shares, shares issued (in shares) | shares	6,900,000
Sponsor Earn-Out Shares, par value (in dollars per shares) | $ / shares	$ 0.0001

Sponsor Earn-Out Liability - Tr

Sponsor Earn-Out Liability - Transfer Restrictions and Forfeiture Terms (Details)	Feb. 02, 2022 D $ / shares
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Sponsor Earn-Out Shares, transfer restrictions, Tranche 1, percentage of total shares (as a percent)	20%
Sponsor Earn-Out Shares, transfer restrictions, Tranche 1, term from closing	180 days
Sponsor Earn-Out Shares, transfer restrictions, Tranche 2, percentage of total shares (as a percent)	20%
Sponsor Earn-Out Shares, transfer restrictions, Tranche 2, minimum share price to exceed (in dollars per share) | $ / shares	$ 12
Sponsor Earn-Out Shares, transfer restrictions, Tranche 2, minimum share price to exceed, trading days (in days)	20
Sponsor Earn-Out Shares, transfer restrictions, Tranche 2, minimum share price to exceed, trading day period (in days)	30
Sponsor Earn-Out Shares, transfer restrictions, Tranche 2, term from closing	150 days
Sponsor Earn-Out Shares, transfer restrictions, Tranche 3, percentage of total shares (as a percent)	20%
Sponsor Earn-Out Shares, transfer restrictions, Tranche 3, minimum share price to exceed (in dollars per share) | $ / shares	$ 14
Sponsor Earn-Out Shares, transfer restrictions, Tranche 3, minimum share price to exceed, trading days (in days)	20
Sponsor Earn-Out Shares, transfer restrictions, Tranche 3, minimum share price to exceed, trading days (in days)	30
Sponsor Earn-Out Shares, transfer restrictions, Tranche 3, term from closing	150 days
Sponsor Earn-Out Shares, transfer restrictions, Tranche 4, percentage of total shares (as a percent)	20%
Sponsor Earn-Out Shares, transfer restrictions, Tranche 4, minimum share price to exceed (in dollars per share) | $ / shares	$ 16
Sponsor Earn-Out Shares, transfer restrictions, Tranche 4, minimum share price to exceed, trading days (in days)	20
Sponsor Earn-Out Shares, transfer restrictions, Tranche 4, minimum share price to exceed, trading days (in days)	30
Sponsor Earn-Out Shares, transfer restrictions, Tranche 4, term from closing	150 days
Sponsor Earn-Out Shares, transfer restrictions, Tranche 5, percentage of total shares (as a percent)	20%
Sponsor Earn-Out Shares, transfer restrictions, Tranche 5, minimum share price to exceed (in dollars per share) | $ / shares	$ 18
Sponsor Earn-Out Shares, transfer restrictions, Tranche 5, minimum share price to exceed, trading days (in days)	20
Sponsor Earn-Out Shares, transfer restrictions, Tranche 5, minimum share price to exceed, trading days (in days)	30
Sponsor Earn-Out Shares, transfer restrictions, Tranche 5, term from closing	150 days
Sponsor Earn-Out Shares, transfer restrictions, change of control, shares released from transfer restrictions, minimum share price to exceed (in dollars per share) | $ / shares	$ 18
Sponsor Earn-Out Shares, transfer restrictions, change of control, shares released from transfer restrictions, percentage of shares (as a percent)	100%
Sponsor Earn-Out Shares, transfer restrictions, change of control, shares released from transfer restrictions, pro rata, maximum share price not to exceed (in dollars per share) | $ / shares	$ 18

Sponsor Earn-Out Liability - Re

Sponsor Earn-Out Liability - Reconciliation (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2023 USD ($)
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	$ 10,961
Change in fair value	(5,412)
Ending Balance	$ 5,549
Fair Value, Liability, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income	Gain (loss) on change in fair value of Sponsor Earn-Out Liability, net

Sponsor Earn-Out Liability - Ke

Sponsor Earn-Out Liability - Key Inputs (Details)	Sep. 30, 2023 Y $ / shares	Dec. 31, 2022 $ / shares Y
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative Liability, Valuation Technique	us-gaap:ValuationTechniqueOptionPricingModelMember	us-gaap:ValuationTechniqueOptionPricingModelMember
Measurement Input, Share Price [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Sponsor earn-out liability, measurement input | $ / shares	2.27	3.15
Measurement Input, Price Volatility [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Sponsor earn-out liability, measurement input	0.840	0.850
Measurement Input, Risk Free Interest Rate [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Sponsor earn-out liability, measurement input	0.0482	0.0409
Measurement Input, Expected Term [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Sponsor earn-out liability, measurement input | Y	3.3	4.1
Measurement Input, Expected Dividend Rate [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Sponsor earn-out liability, measurement input	0	0

Commitments and Contingencies (

Commitments and Contingencies (Details) $ in Millions	Sep. 30, 2023 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Joint development agreements, expenditures related to engineering efforts and purchases of related equipment, maximum	$ 50
Joint development agreements, expenditures related to engineering efforts and purchases of related equipment, cumulative amount spent	$ 8.7

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock-based Compensation Expense - Statement of Operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation	$ 2,418	$ 7,214	$ 16,205	$ 15,947
Research and Development Expense [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation	(1,437)	2,417	2,623	4,678
General and Administrative Expense [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation	$ 3,855	$ 4,797	$ 13,582	$ 11,269

Stock-Based Compensation - St_2

Stock-Based Compensation - Stock-based Compensation Expense - Award Type (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 2,418	$ 7,214	$ 16,205	$ 15,947
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	2,393	2,984	7,077	4,802
Earn-out Shares, Earn-out Restricted Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	(1,597)	2,195	2,704	5,760
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	739	1,345	3,471	2,420
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	782	578	2,638	2,624
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 101	$ 112	$ 315	$ 341

Stock-Based Compensation - Gene

Stock-Based Compensation - General Information (Details)	1 Months Ended
	Apr. 30, 2023 shares
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares, granted (in shares)	4,071,979
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares, granted (in shares)	1,631,800

Income Taxes - Effective Tax Ra

Income Taxes - Effective Tax Rate (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Federal statutory income tax rate (as a percent)	21%	21%	21%	21%
Effective tax rate (as a percent)	(1.50%)	(0.50%)	(1.40%)	(0.70%)

Income Taxes - Unrecognized Tax

Income Taxes - Unrecognized Tax Benefits (Details) $ in Millions	9 Months Ended
	Sep. 30, 2023 USD ($)
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits, period increase (decrease), transfer pricing adjustments	$ 0.9

Net Income (Loss) Per Share - B

Net Income (Loss) Per Share - Basic and Diluted Net Income (Loss) Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022
Net Income (Loss) Available to Common Stockholders, Diluted [Abstract]
Net Income (Loss)	$ (13,473)	$ (12,948)	$ (16,226)	$ (24,328)	$ 9,015	$ (27,033)	$ (42,647)	$ (42,346)
Net loss attributable to common stockholders - basic	(13,473)			(24,328)			(42,647)	(42,346)
Net loss attributable to common stockholders - diluted	$ (13,473)			$ (24,328)			$ (42,647)	$ (42,346)
Weighted Average Number of Shares Outstanding, Diluted [Abstract]
Weighted-average shares of common stock outstanding, basic (in shares)	315,627,263			311,680,656			314,550,810	280,859,250
Weighted-average shares of common stock outstanding, diluted (in shares)	315,627,263			311,680,656			314,550,810	280,859,250
Earnings Per Share, Diluted [Abstract]
Net loss per share attributable to common stockholders - basic (in dollars per share)	$ (0.04)			$ (0.08)			$ (0.14)	$ (0.15)
Net loss per share attributable to common stockholders - diluted (in dollars per share)	$ (0.04)			$ (0.08)			$ (0.14)	$ (0.15)

Net Income (Loss) Per Share - P

Net Income (Loss) Per Share - Potentially Dilutive Securities (Details) - shares	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total	75,546,739	74,479,401
Earn-out Shares, Escrowed Earn-out Shares [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total	27,690,978	27,690,978
Employee Stock Option [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total	16,032,057	18,724,863
Common Stock Warrants, Public Warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total	9,199,947	9,199,947
Earn-out Shares, Sponsor Earn-out Shares [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total	5,520,000	5,520,000
Common Stock Warrants, Private Warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total	5,013,333	5,013,333
Restricted Stock Units (RSUs) [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total	6,350,199	2,755,058
Performance Shares [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total	3,364,810	2,116,942
Earn-out Shares, Earn-out Restricted Shares [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total	1,622,377	1,952,336
Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total	753,038	1,505,944

Related-Party Transactions (Det

Related-Party Transactions (Details)	Sep. 30, 2023	Dec. 31, 2022
Director [Member] | General Motors [Member] | Minimum [Member]
Related Party Transaction [Line Items]
Fully diluted voting interest (as a percent)	5%	5%

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022
Pay vs Performance Disclosure
Net Income (Loss)	$ (13,473)	$ (12,948)	$ (16,226)	$ (24,328)	$ 9,015	$ (27,033)	$ (42,647)	$ (42,346)

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Sep. 30, 2023 shares
Hong Gan [Member]
Trading Arrangements, by Individual
Material Terms of Trading Arrangement	On September 5, 2023, Hong Gan, our Chief Science Officer, adopted a trading plan intended to satisfy the conditions under Rule 10b5-1(c) of the Exchange Act. Mr. Gan’s plan is for the potential exercise sale of up to 450,000 vested stock options with an expiration date of March 14, 2029 and sale of the shares of Class A common stock underlying such stock options. The duration of the trading plan is through August 15, 2024, or earlier, upon the completion of all transactions subject to the trading plan.
Name	Hong Gan
Title	Chief Science Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	September 5, 2023
Aggregate Available	450,000
Expiration Date	March 14, 2029
Jing Nealis [Member]
Trading Arrangements, by Individual
Material Terms of Trading Arrangement	On September 7, 2023, Jing Nealis, our Chief Financial Officer, adopted a trading plan intended to satisfy the conditions under Rule 10b5-1(c) of the Exchange Act. Ms. Nealis’s plan is for the potential sale of up to 870,000 vested stock options with an expiration date of February 10, 2031 and sale of the shares of Class A common stock underlying such stock options. The duration of the trading plan is through August 15, 2024, or earlier, upon the completion of all transactions subject to the trading plan.
Name	Jing Nealis
Title	Chief Financial Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	September 7, 2023
Aggregate Available	870,000
Expiration Date	February 10, 2031
Rohit Makharia [Member]
Trading Arrangements, by Individual
Material Terms of Trading Arrangement	On September 11, 2023, Rohit Makharia, our President and Chief Strategy Officer, adopted a trading plan intended to satisfy the conditions under Rule 10b5-1(c) of the Exchange Act. Mr. Makharia’s plan is for the potential exercise sale of up to 675,000 vested stock options with an expiration date of March 1, 2031 and sale of the shares of Class A common stock underlying such stock options. The duration of the trading plan is through August 15, 2024, or earlier, upon the completion of all transactions subject to the trading plan.
Name	Rohit Makharia
Title	President and Chief Strategy Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	September 11, 2023
Aggregate Available	675,000
Expiration Date	March 1, 2031