SES AI (SES) 10-Q 3 May 24 2024 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - $ / shares	3 Months Ended
	Mar. 31, 2024	Apr. 29, 2024
Document Information [Line Items]
Entity Central Index Key	0001819142
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2024
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	2024
Document Fiscal Period Focus	Q1
Amendment Flag	false
Common Class A
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		313,130,805
Common Class B
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		43,881,251
Warrant
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	Mar. 31, 2024	Dec. 31, 2023
Current Assets
Cash and cash equivalents	$ 129,609	$ 85,671
Short-term investments	189,147	246,775
Receivable from related party	$ 1,217	$ 3,911
Other receivable, after allowance for credit loss, current, related party, type extensible enumeration	Related Party	Related Party
Inventories	$ 425	$ 558
Prepaid expenses and other assets	6,714	11,712
Total current assets	327,112	348,627
Property and equipment, net	40,122	37,959
Intangible assets, net	1,313	1,345
Right-of-use assets, net	11,697	13,099
Deferred tax assets	1,057	1,057
Other assets, non-current	4,583	4,723
Total assets	385,884	406,810
Current Liabilities
Accounts payable	2,762	4,830
Operating lease liabilities	2,436	2,404
Accrued expenses and other liabilities	8,745	13,121
Total current liabilities	13,943	20,355
Sponsor Earn-Out liabilities	3,291	4,166
Operating lease liabilities, non-current	9,687	11,316
Unearned government grant	8,913	9,270
Other liabilities, non-current	2,661	2,753
Total liabilities	38,495	47,860
Commitments and contingencies (Note 9)
Stockholders' Equity
Preferred stock, $0.0001 par value; 20,000,000 shares authorized, none issued and outstanding as of March 31, 2024 and December 31, 2023, respectively
Common stock: Class A shares, $0.0001 par value, 2,100,000,000 shares authorized; 309,736,367 and 310,266,922 shares issued and outstanding as of March 31, 2024 and December 31, 2023, respectively; Class B shares, $0.0001 par value, 200,000,000 shares authorized; 43,881,251 shares issued and outstanding as of March 31, 2024 and December 31, 2023, respectively	35	35
Additional paid-in capital	563,966	559,214
Accumulated deficit	(214,243)	(198,686)
Accumulated other comprehensive loss	(2,369)	(1,613)
Total stockholders' equity	347,389	358,950
Total liabilities and stockholders' equity	$ 385,884	$ 406,810

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2024	Dec. 31, 2023
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized (in shares)	20,000,000	20,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
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)	309,736,367	310,266,922
Common stock, shares outstanding (in shares)	309,736,367	310,266,922
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 Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Operating expenses:
Research and development	$ 11,765	$ 8,489
General and administrative	9,506	13,123
Total operating expenses	21,271	21,612
Loss from operations	(21,271)	(21,612)
Other income:
Interest income	4,162	4,140
Gain on change in fair value of Sponsor Earn-Out liabilities	875	569
Miscellaneous income, net	874	820
Total other income, net	5,911	5,529
Loss before income taxes	(15,360)	(16,083)
Provision for income taxes	(197)	(143)
Net loss	(15,557)	(16,226)
Other comprehensive (loss) income, net of tax:
Foreign currency translation adjustment	(457)	72
Unrealized (loss) gain on short-term investments	(299)	467
Total other comprehensive (loss) income, net of tax	(756)	539
Total comprehensive loss	$ (16,313)	$ (15,687)
Net loss per share attributable to common stockholders - basic (in dollars per share)	$ (0.05)	$ (0.05)
Net loss per share attributable to common stockholders - diluted (in dollars per share)	$ (0.05)	$ (0.05)
Weighted-average common shares outstanding, basic (in shares)	318,790,719	313,422,442
Weighted-average common shares outstanding, diluted (in shares)	318,790,719	313,422,442

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Total
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]
Issuance of common stock upon exercise of stock options		13			13
Issuance of common stock upon exercise of stock options (in shares)	94,319
Restricted stock units vested (in shares)	4,727
Forfeitures of Earn-Out Restricted Shares	(1,904)
Stock-based compensation		6,462			6,462
Net loss			(16,226)		(16,226)
Unrealized (loss) gain on short-term 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, 2023	$ 35	559,214	(198,686)	(1,613)	358,950
Beginning balance (in shares) at Dec. 31, 2023	354,148,173
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options		18			18
Issuance of common stock upon exercise of stock options (in shares)	197,127
Restricted stock units vested (in shares)	18,869
Forfeitures of Earn-Out Restricted Shares	(711,298)
Forfeitures of Restricted Stock Awards		(50)			(50)
Forfeitures of Restricted Stock Awards (in shares)	(35,253)
Stock-based compensation		4,784			4,784
Net loss			(15,557)		(15,557)
Unrealized (loss) gain on short-term investments				(299)	(299)
Foreign currency translation adjustments				(457)	(457)
Ending balance at Mar. 31, 2024	$ 35	$ 563,966	$ (214,243)	$ (2,369)	$ 347,389
Ending balance (in shares) at Mar. 31, 2024	353,617,618

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Cash Flows From Operating Activities
Net loss	$ (15,557)	$ (16,226)
Adjustments to reconcile net loss to net cash used in operating activities:
Gain from change in fair value of Sponsor Earn-Out liabilities	(875)	(569)
Stock-based compensation	4,784	6,462
Depreciation and amortization	1,721	1,060
Accretion income from available-for-sale short-term investments	(1,889)	(2,946)
Other	(894)	(683)
Changes in operating assets and liabilities:
Receivable from related party	2,694	(422)
Inventories	121	(120)
Prepaid expenses and other assets	4,993	(2,553)
Right-of-use assets	1,280	(276)
Accounts payable	(249)	(15)
Accrued expenses and other liabilities	(3,637)	941
Operating lease liabilities	(1,471)	(46)
Net cash used in operating activities	(8,979)	(15,393)
Cash Flows From Investing Activities
Purchases of property and equipment	(6,758)	(5,974)
Purchase of short-term investments		(97,119)
Proceeds from the maturities of short-term investments	60,000	60,000
Net cash provided by (used in) investing activities	53,242	(43,093)
Cash Flows From Financing Activities
Proceeds from stock option exercises	18	13
Net cash provided by financing activities	18	13
Effect of exchange rates on cash	(369)	(198)
Net increase (decrease) in cash, cash equivalents and restricted cash	43,912	(58,671)
Cash, cash equivalents and restricted cash at beginning of period (Note 4)	86,966	107,936
Cash, cash equivalents and restricted cash at end of period (Note 4)	130,878	49,265
Supplemental Cash and Non-Cash Information:
Income taxes paid	3	47
Accounts payable and accrued expenses related to purchases of property and equipment	$ 3,535	1,034
Operating lease liabilities arising from obtaining right-of-use assets		$ 776

Nature of Business

Nature of Business	3 Months Ended
	Mar. 31, 2024
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 power a new era of electric transportation on land and in air with Li-Metal batteries. Our differentiated battery technology has been designed to combine the high energy density of Li-Metal with the 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 is 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 March 31, 2024, 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	3 Months Ended
	Mar. 31, 2024
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 unaudited interim 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 The results of operations for the three months ended March 31, 2024 are not necessarily indicative of the results that may be expected for the full year or any other future interim or annual periods. The Company’s fiscal year ends on December 31. The year-end balance sheet data was derived from audited consolidated financial statements. These unaudited interim condensed consolidated 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, 2023 included in the Company’s Annual Report on Form 10-K filed with the SEC on February 27, 2024 (the “Annual Report”). Use of estimates The preparation of these unaudited interim 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 Company’s (as defined below in Note 8), the Sponsor Earn-Out Shares, the Earn-Out Restricted Shares, restricted stock awards, stock options, and performance stock units, (ii) deferred tax assets and uncertain income tax positions, and (iii) 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 short-term marketable debt and marketable equity securities. Investments in marketable debt securities consist of U.S. treasury securities, are classified as available-for-sale at the time of purchase and reevaluate such classification at each balance sheet date. These available-for-sale marketable securities are recorded at fair value, with any unrealized gains and losses included as a component of accumulated other comprehensive (loss) income in total stockholders’ equity on the unaudited interim condensed 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 U.S. treasury securities is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion are reported within interest income in the unaudited interim condensed 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 these 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 unaudited interim condensed consolidated balance sheet, respectively. Investments in marketable equity securities are classified as short-term investments when the Company’s intention is to sell within a year from the reporting period end, otherwise they will be classified as long-term investments. Investments in marketable equity securities with a readily determinable fair value, not accounted for under the equity method, are recorded at fair value with unrealized gains and losses reported within miscellaneous income, net in the unaudited interim condensed consolidated statements of operations and comprehensive loss. Inventories Inventories consist of raw materials and are stated at the lower of average cost or net realizable value. 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 March 31, 2024 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Current Assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents in money market funds (Note 4) $ 120,442 ​ $ — ​ $ — ​ $ 120,442 U.S. treasury securities ​ 187,717 ​ ​ — ​ ​ — ​ ​ 187,717 Equity securities (1) ​ 1,430 ​ ​ — ​ ​ — ​ ​ 1,430 Total current assets at fair value $ 309,589 ​ $ — ​ $ — ​ $ 309,589 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 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 $ 310,203 ​ $ — ​ $ — ​ $ 310,203 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Sponsor Earn-Out liabilities $ — ​ $ — ​ $ 3,291 ​ $ 3,291 Total liabilities at fair value $ — ​ $ — ​ $ 3,291 ​ $ 3,291 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2023 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Current Assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents in money market funds (Note 4) $ 74,997 ​ $ — ​ $ — ​ $ 74,997 U.S. treasury securities ​ 246,127 ​ ​ — ​ ​ — ​ ​ 246,127 Equity securities (1) ​ 648 ​ ​ — ​ ​ — ​ ​ 648 Total current assets at fair value $ 321,772 ​ $ — ​ $ — ​ $ 321,772 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 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 $ 322,386 ​ $ — ​ $ — ​ $ 322,386 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Sponsor Earn-Out liabilities $ — ​ $ — ​ $ 4,166 ​ $ 4,166 Total liabilities at fair value $ — ​ $ — ​ $ 4,166 ​ $ 4,166 (1) ​ There were no transfers in or out of Level 3 measurements during the three months ended March 31, 2024. Recently Adopted Accounting Pronouncements In November 2023, the FASB issued ASU 2023-7, Improvements to Reportable Segment Disclosures , which requires ​ In December 2023, the FASB issued ASU 2023-9, Improvements to Income Tax Disclosures , which requires disaggregated information about a reporting entity’s effective tax rate reconciliation as well as additional information on income taxes paid. The ASU is effective on a prospective basis for annual periods beginning after December 15, 2024. Early adoption is also permitted for annual financial statements that have not yet been issued or made available for issuance. We are currently evaluating the impact this ASU will have when adopted and anticipate this ASU will likely result in the required additional disclosures being included in our consolidated financial statements. ​ Climate-Related Disclosures ​ In March 2024, the SEC adopted final rules that would require registrants to provide certain climate-related information in their registration statements and annual reports. The new rules require information about a registrant's climate-related risks that are reasonably likely to have a material impact on its business, results of operations, or financial condition. The rules also require disclosure of a registrant’s greenhouse gas emissions and certain climate-related financial metrics in their audited financial statements. In April 2024, the SEC voluntarily stayed the rules pending completion of a judicial review that is currently pending in the U.S. Court of Appeals for the Eighth Circuit. We are currently evaluating the impact these rules will have when adopted and anticipate these rules will likely result in the required additional disclosures being included in on our consolidated financial statements. ​ The Company has reviewed all accounting pronouncements issued during the three months ended March 31, 2024 and concluded they were either not applicable or not expected to have a material impact on the Company’s unaudited interim condensed consolidated financial statements.

Partnerships

Partnerships	3 Months Ended
	Mar. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Partnerships	Note 3. 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, which concluded in November 2023. Further, in May 2021, the Company executed another JDA with Hyundai to jointly develop an A-Sample Li-Metal battery effective August 31, 2021. In March 2024, the Company extended this JDA until December 2025 to develop the B-sample Li-Metal battery. 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 and build-out a prototype manufacturing line for GM Technology. The JDA has an initial term of three years, which can be extended based on mutual agreement. In December 2021, the Company established a partnership with Honda Motor Company, Ltd. (“Honda”) when it entered into a JDA to jointly R&D an A-Sample Li-Metal battery, which concluded in June 2023. In November 2023, the Company entered into a B-Sample JDA with one of our OEM partners for delivery of B-Sample battery. The JDA has a term of two Under the terms of certain JDAs, the Company will fund research and development activities and capital expenditures related to the buildout of pilot manufacturing lines and the JDA partner will be required to refund such expenses to the Company, regardless of the results of the research and development activities. The following table summarizes the expenses incurred by the Company that were recorded as a credit to research and development expense in the unaudited interim condensed consolidated statements of operations and comprehensive loss: ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, (in thousands) 2024 2023 Research and development (related party) $ 1,217 ​ $ 1,771 Research and development (non-related party) ​ 2,308 ​ ​ 1,416 Total reimbursements to research and development $ 3,525 ​ $ 3,186 ​ As of March 31, 2024 and December 31, 2023, $1.2 million and $3.9 million was outstanding as a receivable from related party as disclosed in the unaudited interim condensed consolidated balance sheets. As of March 31, 2024 and December 31, 2023, none and $5.1 million was recorded as receivable from non-related party JDAs. As of March 31, 2024 and December 31, 2023, $0.1 million and none was recorded as deferred income for non-related party JDAs. Amounts for non-related party receivables are recorded within prepaid expenses and other current assets and the deferred income is recorded within accrued expenses and other current liabilities in the unaudited interim condensed consolidated balance sheets .

Cash and Cash Equivalents

Cash and Cash Equivalents	3 Months Ended
	Mar. 31, 2024
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) March 31, 2024 December 31, 2023 Cash $ 9,167 ​ $ 10,674 Money market funds 120,442 ​ 74,997 Total cash and cash equivalents ​ 129,609 ​ ​ 85,671 Restricted cash included in other assets 1,269 ​ 1,295 Total cash, cash equivalents, and restricted cash shown in the unaudited condensed consolidated statements of cash flows $ 130,878 ​ $ 86,966 ​ ​ ​ 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.

Short-Term Investments

Short-Term Investments	3 Months Ended
	Mar. 31, 2024
Investments, Debt and Equity Securities [Abstract]
Short-Term Investments	Note 5. Short-Term Investments The following table provides amortized costs, gross unrealized gains and losses, and fair values for the Company’s investments in available-for-sale U.S. treasury securities as of March 31, 2024 and December 31, 2023, which have maturity dates that range from 1 month to 7 months and 1 month to 10 months, respectively. Fair value was determined using market prices obtained from third-party sources. Realized gains or losses were insignificant for the three months ended March 31, 2024 and 2023. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2024 ​ ​ ​ Gross ​ Gross ​ ​ ​ (in thousands) Amortized Cost Unrealized Gains Unrealized Losses Fair Value Short-term U.S. treasury securities $ 187,686 ​ $ 43 ​ $ (12) ​ $ 187,717 Total $ 187,686 ​ $ 43 ​ $ (12) ​ $ 187,717 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2023 ​ ​ ​ Gross ​ Gross ​ ​ ​ (in thousands) Amortized Cost Unrealized Gains Unrealized Losses Fair Value Short-term U.S. treasury securities $ 245,797 ​ $ 337 ​ $ (7) ​ $ 246,127 Total $ 245,797 ​ $ 337 ​ $ (7) ​ $ 246,127

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	3 Months Ended
	Mar. 31, 2024
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) March 31, 2024 December 31, 2023 Employee compensation and related costs $ 3,460 ​ $ 7,022 Construction in process ​ 2,494 ​ ​ 3,182 Income taxes payable ​ 454 ​ ​ 288 Professional and consulting services ​ 552 ​ ​ 1,273 Deferred income received under partnerships ​ 77 ​ ​ — Other 1,708 ​ 1,356 Accrued expenses and other current liabilities $ 8,745 ​ $ 13,121

Government Grant

Government Grant	3 Months Ended
	Mar. 31, 2024
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 to the following conditions attached to the incentives, which include purchase of a government grant guarantee insurance policy, 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 , with the option to extend to 10 years by remaining in a certain geographical location. If subsequently it was determined that we were in non-compliance with the Grant conditions, we could be required to pay the Grant in its entirety with interest. The Company has yet to fulfill the required minimum investment, and the compliance with this condition will continue to be monitored over the remaining grant period. As of March 31, 2024 and December 31, 2023, the Company has received, but not yet earned, cash grants of 12.0 billion Korean won. These balances are equivalent to $8.9 million and $9.3 million after translation, respectively, as of March 31, 2024 and December 31, 2023, which is disclosed as a noncurrent liability in the unaudited interim condensed consolidated balance sheets. ​

Sponsor Earn-Out Liabilities

Sponsor Earn-Out Liabilities	3 Months Ended
	Mar. 31, 2024
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Sponsor Earn-Out Liabilities	Note 8. Sponsor Earn-Out Liabilities In connection with the closing of the Business Combination (the “Closing”) on February 3, 2022 (the “Closing Date”), Ivanhoe Capital Acquisition Corp. (“Ivanhoe”), a Cayman Islands exempted company, migrated out of the Cayman Islands and domesticated as a Delaware corporation (the “Domestication”), changed its name to “SES AI Corporation”, and Wormhole Amalgamation Sub Pte. Ltd., a Singapore private company limited by shares and a direct, wholly-owned subsidiary of Ivanhoe (“Amalgamation Sub”), consummated the previously announced Business Combination (the “Business Combination”) pursuant to which, among other things, Amalgamation Sub merged with and into SES Holdings Pte. Ltd., a Singapore private company limited by shares (“Old SES”), with Old SES surviving the Business Combination as a wholly-owned subsidiary of SES. 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 upon a change in control. 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 liabilities 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 liabilities are measured at estimated fair value using Level 3 inputs in a Monte Carlo simulation valuation model. liabilities The following table provides a reconciliation of the beginning and ending balances for the Sponsor Earn-Out liabilities: ​ ​ ​ ​ (in thousands) ​ ​ Balance as of December 31, 2023 $ 4,166 Change in fair value (875) Balance as of March 31, 2024 $ 3,291 ​ ​ ​ Balance as of December 31, 2022 $ 10,961 Change in fair value ​ (569) Balance as of March 31, 2023 $ 10,392 ​ ​ ​ ​ Inherent in the valuation model are assumptions related to expected stock price volatility, risk-free interest rate, expected term, and dividend yield. The key inputs used in the Monte Carlo simulation model at their respective measurement dates were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2024 ​ ​ December 31, 2023 Expected term (in years) ​ 3.1 ​ ​ 3.1 Risk free rate ​ 4.30% ​ ​ 4.04% Expected volatility ​ 85.0% ​ ​ 91.0% Expected dividends ​ 0% ​ ​ 0% Stock price $ 1.68 ​ $ 1.83 ​ 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 a weighted average of historical volatilities of SES’s shares and warrants and select peer companies’ common stock that matches the expected term of the awards (range of the weighted average of volatility was 78.2% - 89.2% and 83.8% - 96.2% as of March 31, 2024 and December 31, 2023, respectively). The expected term is derived from a probability weighted model, considering a number of inputs, including the probability of a change in control. The risk-free interest rate is based on the yield curve for zero-coupon U.S. Treasury notes with maturities corresponding to the expected term of the awards. The dividend rate is based on the historical rate, which the Company anticipates remaining at zero.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2024
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 9. Commitments and Contingencies Commitments Under the terms of one of the JDAs entered into in 2021 and amended in March 2024, 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. The Company has a commitment to spend up to $35 million under this JDA as of March 31, 2024. In December 2021, the Company amended the lease agreement for an office space in Woburn, Massachusetts. The amendment includes an obligation for the Company 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 the monthly rental amount and the lessor has provided a notice to collect the relinquishment charges from the Company. As of March 31, 2024, 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	3 Months Ended
	Mar. 31, 2024
Share-Based Payment Arrangement [Abstract]
Stock-Based Compensation	Note 10. Stock-Based Compensation The Company’s stock-based compensation included in its unaudited interim condensed consolidated statements of operations and comprehensive loss, net of forfeitures, was as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, (in thousands) 2024 2023 Research and development ​ $ 1,451 ​ $ 1,847 General and administrative ​ 3,333 ​ 4,615 Total stock-based compensation ​ $ 4,784 ​ $ 6,462 ​ The following table summarizes stock-based compensation expense by award type, : ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, (in thousands) ​ 2024 ​ 2023 Earn-Out Restricted Shares ​ $ — ​ $ 2,135 Restricted Stock Units ("RSUs") ​ ​ 3,085 ​ ​ 1,961 Performance Stock Units ("PSUs") ​ ​ 932 ​ ​ 1,326 Restricted Stock Awards ("RSAs") ​ ​ 491 ​ ​ 930 Stock options ​ ​ 276 ​ ​ 110 Total ​ $ 4,784 ​ $ 6,462 ​ In February 2024, the Company granted 8,996,931 RSUs and 3,280,083 PSUs, which relates to the annual grant to our directors, executive officers and employees.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2024
Income Tax Disclosure [Abstract]
Income Taxes	Note 11. Income Taxes The Company’s effective tax rate for the three months ended March 31, 2024 was (1.8)% compared with (0.9)% for the three months ended March 31, 2023. 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 March 31, 2024 and December 31, 2023 and the recording of uncertain tax positions and interest expense.

Net Loss Per Share

Net Loss Per Share	3 Months Ended
	Mar. 31, 2024
Earnings Per Share [Abstract]
Net Loss Per Share	Note 12. Net Loss Per Share Basic net loss per share is computed by dividing net loss by the weighted average number of common shares outstanding for the period. Diluted net loss per share is computed by dividing net 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 loss per share were as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, (in thousands, except share and per share amounts) 2024 2023 Numerator: ​ ​ ​ ​ Net loss attributable to common stockholders - basic ​ $ (15,557) ​ $ (16,226) ​ ​ ​ ​ ​ ​ ​ Denominator: ​ ​ ​ ​ ​ ​ Weighted average shares of common stock outstanding - basic and diluted ​ 318,790,719 ​ 313,422,442 ​ ​ ​ ​ ​ ​ ​ Net loss per share attributable to common stockholders - basic and diluted ​ $ (0.05) ​ $ (0.05) ​ 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 March 31, ​ ​ ​ 2024 ​ 2023 Escrowed earn-out shares ​ ​ 27,690,978 ​ ​ 27,690,978 ​ Options to purchase common stock ​ ​ 12,381,133 ​ ​ 18,203,903 ​ 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 ​ ​ 16,525,573 ​ ​ 2,789,984 ​ Unvested PSUs ​ ​ 6,812,398 ​ ​ 2,116,942 ​ Earn-out Restricted Shares ​ ​ 908,700 ​ ​ 1,929,140 ​ Unvested RSAs ​ ​ 551,774 ​ ​ 1,090,610 ​ Total ​ ​ 84,603,836 ​ ​ 73,554,837 ​

Related-Party Transactions

Related-Party Transactions	3 Months Ended
	Mar. 31, 2024
Related Party Transactions [Abstract]
Related-Party Transactions	Note 13. Related-Party Transactions As of March 31, 2024 and December 31, 2023, General Motors Company and its affiliates (“GM”) were considered a related party due to their board representation and the board member’s employment position at GM, as well as GM holding more than 5% of the fully diluted outstanding equity securities of SES. 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)	3 Months Ended
	Mar. 31, 2024
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited interim 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 The results of operations for the three months ended March 31, 2024 are not necessarily indicative of the results that may be expected for the full year or any other future interim or annual periods. The Company’s fiscal year ends on December 31. The year-end balance sheet data was derived from audited consolidated financial statements. These unaudited interim condensed consolidated 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, 2023 included in the Company’s Annual Report on Form 10-K filed with the SEC on February 27, 2024 (the “Annual Report”).
Use of Estimates	Use of estimates The preparation of these unaudited interim 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 Company’s (as defined below in Note 8), the Sponsor Earn-Out Shares, the Earn-Out Restricted Shares, restricted stock awards, stock options, and performance stock units, (ii) deferred tax assets and uncertain income tax positions, and (iii) 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 short-term marketable debt and marketable equity securities. Investments in marketable debt securities consist of U.S. treasury securities, are classified as available-for-sale at the time of purchase and reevaluate such classification at each balance sheet date. These available-for-sale marketable securities are recorded at fair value, with any unrealized gains and losses included as a component of accumulated other comprehensive (loss) income in total stockholders’ equity on the unaudited interim condensed 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 U.S. treasury securities is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion are reported within interest income in the unaudited interim condensed 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 these 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 unaudited interim condensed consolidated balance sheet, respectively. Investments in marketable equity securities are classified as short-term investments when the Company’s intention is to sell within a year from the reporting period end, otherwise they will be classified as long-term investments. Investments in marketable equity securities with a readily determinable fair value, not accounted for under the equity method, are recorded at fair value with unrealized gains and losses reported within miscellaneous income, net in the unaudited interim condensed consolidated statements of operations and comprehensive loss.
Inventories	Inventories Inventories consist of raw materials and are stated at the lower of average cost or net realizable value.
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 March 31, 2024 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Current Assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents in money market funds (Note 4) $ 120,442 ​ $ — ​ $ — ​ $ 120,442 U.S. treasury securities ​ 187,717 ​ ​ — ​ ​ — ​ ​ 187,717 Equity securities (1) ​ 1,430 ​ ​ — ​ ​ — ​ ​ 1,430 Total current assets at fair value $ 309,589 ​ $ — ​ $ — ​ $ 309,589 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 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 $ 310,203 ​ $ — ​ $ — ​ $ 310,203 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Sponsor Earn-Out liabilities $ — ​ $ — ​ $ 3,291 ​ $ 3,291 Total liabilities at fair value $ — ​ $ — ​ $ 3,291 ​ $ 3,291 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2023 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Current Assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents in money market funds (Note 4) $ 74,997 ​ $ — ​ $ — ​ $ 74,997 U.S. treasury securities ​ 246,127 ​ ​ — ​ ​ — ​ ​ 246,127 Equity securities (1) ​ 648 ​ ​ — ​ ​ — ​ ​ 648 Total current assets at fair value $ 321,772 ​ $ — ​ $ — ​ $ 321,772 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 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 $ 322,386 ​ $ — ​ $ — ​ $ 322,386 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Sponsor Earn-Out liabilities $ — ​ $ — ​ $ 4,166 ​ $ 4,166 Total liabilities at fair value $ — ​ $ — ​ $ 4,166 ​ $ 4,166 (1) ​ There were no transfers in or out of Level 3 measurements during the three months ended March 31, 2024.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements In November 2023, the FASB issued ASU 2023-7, Improvements to Reportable Segment Disclosures , which requires ​ In December 2023, the FASB issued ASU 2023-9, Improvements to Income Tax Disclosures , which requires disaggregated information about a reporting entity’s effective tax rate reconciliation as well as additional information on income taxes paid. The ASU is effective on a prospective basis for annual periods beginning after December 15, 2024. Early adoption is also permitted for annual financial statements that have not yet been issued or made available for issuance. We are currently evaluating the impact this ASU will have when adopted and anticipate this ASU will likely result in the required additional disclosures being included in our consolidated financial statements. ​ Climate-Related Disclosures ​ In March 2024, the SEC adopted final rules that would require registrants to provide certain climate-related information in their registration statements and annual reports. The new rules require information about a registrant's climate-related risks that are reasonably likely to have a material impact on its business, results of operations, or financial condition. The rules also require disclosure of a registrant’s greenhouse gas emissions and certain climate-related financial metrics in their audited financial statements. In April 2024, the SEC voluntarily stayed the rules pending completion of a judicial review that is currently pending in the U.S. Court of Appeals for the Eighth Circuit. We are currently evaluating the impact these rules will have when adopted and anticipate these rules will likely result in the required additional disclosures being included in on our consolidated financial statements. ​ The Company has reviewed all accounting pronouncements issued during the three months ended March 31, 2024 and concluded they were either not applicable or not expected to have a material impact on the Company’s unaudited interim condensed consolidated financial statements.

Basis of Presentation and Sum_3

Basis of Presentation and Summary of Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2024
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 March 31, 2024 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Current Assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents in money market funds (Note 4) $ 120,442 ​ $ — ​ $ — ​ $ 120,442 U.S. treasury securities ​ 187,717 ​ ​ — ​ ​ — ​ ​ 187,717 Equity securities (1) ​ 1,430 ​ ​ — ​ ​ — ​ ​ 1,430 Total current assets at fair value $ 309,589 ​ $ — ​ $ — ​ $ 309,589 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 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 $ 310,203 ​ $ — ​ $ — ​ $ 310,203 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Sponsor Earn-Out liabilities $ — ​ $ — ​ $ 3,291 ​ $ 3,291 Total liabilities at fair value $ — ​ $ — ​ $ 3,291 ​ $ 3,291 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2023 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Current Assets ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash equivalents in money market funds (Note 4) $ 74,997 ​ $ — ​ $ — ​ $ 74,997 U.S. treasury securities ​ 246,127 ​ ​ — ​ ​ — ​ ​ 246,127 Equity securities (1) ​ 648 ​ ​ — ​ ​ — ​ ​ 648 Total current assets at fair value $ 321,772 ​ $ — ​ $ — ​ $ 321,772 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 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 $ 322,386 ​ $ — ​ $ — ​ $ 322,386 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Liabilities ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Sponsor Earn-Out liabilities $ — ​ $ — ​ $ 4,166 ​ $ 4,166 Total liabilities at fair value $ — ​ $ — ​ $ 4,166 ​ $ 4,166 (1)

Partnerships (Tables)

Partnerships (Tables)	3 Months Ended
	Mar. 31, 2024
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 March 31, (in thousands) 2024 2023 Research and development (related party) $ 1,217 ​ $ 1,771 Research and development (non-related party) ​ 2,308 ​ ​ 1,416 Total reimbursements to research and development $ 3,525 ​ $ 3,186

Cash and Cash Equivalents (Tabl

Cash and Cash Equivalents (Tables)	3 Months Ended
	Mar. 31, 2024
Cash and Cash Equivalents [Abstract]
Schedule of cash, cash equivalents, and restricted cash	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) March 31, 2024 December 31, 2023 Cash $ 9,167 ​ $ 10,674 Money market funds 120,442 ​ 74,997 Total cash and cash equivalents ​ 129,609 ​ ​ 85,671 Restricted cash included in other assets 1,269 ​ 1,295 Total cash, cash equivalents, and restricted cash shown in the unaudited condensed consolidated statements of cash flows $ 130,878 ​ $ 86,966

Short-Term Investments (Tables)

Short-Term Investments (Tables)	3 Months Ended
	Mar. 31, 2024
Investments, Debt and Equity Securities [Abstract]
Schedule of amortized costs, gross unrealized gains and losses, and fair values of investments	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2024 ​ ​ ​ Gross ​ Gross ​ ​ ​ (in thousands) Amortized Cost Unrealized Gains Unrealized Losses Fair Value Short-term U.S. treasury securities $ 187,686 ​ $ 43 ​ $ (12) ​ $ 187,717 Total $ 187,686 ​ $ 43 ​ $ (12) ​ $ 187,717 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ December 31, 2023 ​ ​ ​ Gross ​ Gross ​ ​ ​ (in thousands) Amortized Cost Unrealized Gains Unrealized Losses Fair Value Short-term U.S. treasury securities $ 245,797 ​ $ 337 ​ $ (7) ​ $ 246,127 Total $ 245,797 ​ $ 337 ​ $ (7) ​ $ 246,127

Accrued Expenses and Other Cu_2

Accrued Expenses and Other Current Liabilities (Tables)	3 Months Ended
	Mar. 31, 2024
Payables and Accruals [Abstract]
Schedule of accrued expenses and other current liabilities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ (in thousands) March 31, 2024 December 31, 2023 Employee compensation and related costs $ 3,460 ​ $ 7,022 Construction in process ​ 2,494 ​ ​ 3,182 Income taxes payable ​ 454 ​ ​ 288 Professional and consulting services ​ 552 ​ ​ 1,273 Deferred income received under partnerships ​ 77 ​ ​ — Other 1,708 ​ 1,356 Accrued expenses and other current liabilities $ 8,745 ​ $ 13,121

Sponsor Earn-Out Liabilities (T

Sponsor Earn-Out Liabilities (Tables)	3 Months Ended
	Mar. 31, 2024
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of the reconciliation of the Sponsor Earn-Out liability	​ ​ ​ ​ (in thousands) ​ ​ Balance as of December 31, 2023 $ 4,166 Change in fair value (875) Balance as of March 31, 2024 $ 3,291 ​ ​ ​ Balance as of December 31, 2022 $ 10,961 Change in fair value ​ (569) Balance as of March 31, 2023 $ 10,392 ​ ​ ​
Schedule of key inputs into the Monte Carlo simulation model for the Sponsor Earn-Out liability	​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2024 ​ ​ December 31, 2023 Expected term (in years) ​ 3.1 ​ ​ 3.1 Risk free rate ​ 4.30% ​ ​ 4.04% Expected volatility ​ 85.0% ​ ​ 91.0% Expected dividends ​ 0% ​ ​ 0% Stock price $ 1.68 ​ $ 1.83

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2024
Share-Based Payment Arrangement [Abstract]
Summary of compensation expense related to stock-based awards	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, (in thousands) 2024 2023 Research and development ​ $ 1,451 ​ $ 1,847 General and administrative ​ 3,333 ​ 4,615 Total stock-based compensation ​ $ 4,784 ​ $ 6,462
Summary of share-based compensation expense by award type	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, (in thousands) ​ 2024 ​ 2023 Earn-Out Restricted Shares ​ $ — ​ $ 2,135 Restricted Stock Units ("RSUs") ​ ​ 3,085 ​ ​ 1,961 Performance Stock Units ("PSUs") ​ ​ 932 ​ ​ 1,326 Restricted Stock Awards ("RSAs") ​ ​ 491 ​ ​ 930 Stock options ​ ​ 276 ​ ​ 110 Total ​ $ 4,784 ​ $ 6,462

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	3 Months Ended
	Mar. 31, 2024
Earnings Per Share [Abstract]
Schedule of calculation of basic and diluted net income per share	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, (in thousands, except share and per share amounts) 2024 2023 Numerator: ​ ​ ​ ​ Net loss attributable to common stockholders - basic ​ $ (15,557) ​ $ (16,226) ​ ​ ​ ​ ​ ​ ​ Denominator: ​ ​ ​ ​ ​ ​ Weighted average shares of common stock outstanding - basic and diluted ​ 318,790,719 ​ 313,422,442 ​ ​ ​ ​ ​ ​ ​ Net loss per share attributable to common stockholders - basic and diluted ​ $ (0.05) ​ $ (0.05)
Schedule of potentially anti-dilutive securities	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ As of March 31, ​ ​ ​ 2024 ​ 2023 Escrowed earn-out shares ​ ​ 27,690,978 ​ ​ 27,690,978 ​ Options to purchase common stock ​ ​ 12,381,133 ​ ​ 18,203,903 ​ 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 ​ ​ 16,525,573 ​ ​ 2,789,984 ​ Unvested PSUs ​ ​ 6,812,398 ​ ​ 2,116,942 ​ Earn-out Restricted Shares ​ ​ 908,700 ​ ​ 1,929,140 ​ Unvested RSAs ​ ​ 551,774 ​ ​ 1,090,610 ​ Total ​ ​ 84,603,836 ​ ​ 73,554,837 ​

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	Mar. 31, 2024	Dec. 31, 2023
Assets, Fair Value Disclosure [Abstract]
Debt securities, available-for-sale, current	$ 189,147	$ 246,775
Restricted cash and cash equivalents, noncurrent	$ 1,269	$ 1,295
Financial Liabilities Fair Value Disclosure [Abstract]
Derivative Liability, Statement of Financial Position	Sponsor Earn-Out liabilities	Sponsor Earn-Out liabilities
Fair Value, Recurring
Assets, Fair Value Disclosure [Abstract]
Debt securities, available-for-sale, current	$ 187,717	$ 246,127
Equity securities	1,430	648
Total current assets at fair value	309,589	321,772
Total non-current assets at fair value	614	614
Assets	310,203	322,386
Financial Liabilities Fair Value Disclosure [Abstract]
Sponsor Earn-Out liabilities	3,291	4,166
Total liabilities at fair value	3,291	4,166
Fair Value, Recurring | Money Market Funds
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents	120,442	74,997
Restricted cash and cash equivalents, noncurrent	614	614
Fair Value, Recurring | Fair Value, Inputs, Level 1
Assets, Fair Value Disclosure [Abstract]
Debt securities, available-for-sale, current	187,717	246,127
Equity securities	1,430	648
Total current assets at fair value	309,589	321,772
Total non-current assets at fair value	614	614
Assets	310,203	322,386
Fair Value, Recurring | Fair Value, Inputs, Level 1 | Money Market Funds
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents	120,442	74,997
Restricted cash and cash equivalents, noncurrent	614	614
Fair Value, Recurring | Fair Value, Inputs, Level 3
Financial Liabilities Fair Value Disclosure [Abstract]
Sponsor Earn-Out liabilities	3,291	4,166
Total liabilities at fair value	$ 3,291	$ 4,166

Basis of Presentation and Sig_2

Basis of Presentation and Significant Accounting Policies - Fair Value - Transfers (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2024 USD ($)
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

Partnerships - General Informat

Partnerships - General Information (Details) - USD ($) $ in Millions	1 Months Ended
	Nov. 30, 2023	Feb. 28, 2021	Mar. 31, 2024	Dec. 31, 2023
Original Equipment Manufacturing Partners
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Joint development agreements, period	2 years 6 months
Related Party
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Other receivables			$ 1.2	$ 3.9
Director | GM Global Technology Operations LLC, Affiliate of General Motors Ventures LLC and General Motors Holdings LLC
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Joint development agreements, period		3 years
Nonrelated Party
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Other receivables			0	5.1
Joint development agreements, deferred income			$ 0.1	$ 0

Partnerships - Credits to Resea

Partnerships - Credits to Research and Development (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Research and development (related party)	$ 1,217	$ 1,771
Research and development (non-related party)	2,308	1,416
Total credits to research and development	$ 3,525	$ 3,186

Cash and Cash Equivalents (Deta

Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash	$ 9,167	$ 10,674
Money market funds	120,442	74,997
Total cash and cash equivalents	129,609	85,671
Restricted cash included in other assets	$ 1,269	$ 1,295
Restricted Cash and Cash Equivalents, Noncurrent, Statement of Financial Position	Other assets, non-current	Other assets, non-current
Total cash, cash equivalents, and restricted cash shown in the unaudited condensed consolidated statements of cash flows	$ 130,878	$ 86,966	$ 49,265	$ 107,936

Short-Term Investments - Genera

Short-Term Investments - General Information (Details)	Mar. 31, 2024	Dec. 31, 2023
Minimum
Debt Securities, Available-for-Sale [Abstract]
Debt securities, available-for-sale, term	1 month	1 month
Maximum
Debt Securities, Available-for-Sale [Abstract]
Debt securities, available-for-sale, term	7 months	10 months

Short-Term Investments - Tabula

Short-Term Investments - Tabular Disclosure (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Debt Securities, Available-for-Sale, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Debt securities, available-for-sale, current	$ 189,147	$ 246,775
Amortized cost	187,686	245,797
Gross unrealized gains	43	337
Gross unrealized losses	(12)	(7)
Fair value	187,717	246,127
US Treasury and Government
Debt Securities, Available-for-Sale, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Amortized cost, current	187,686	245,797
Gross unrealized gains, current	43	337
Gross unrealized losses, current	(12)	(7)
Debt securities, available-for-sale, current	$ 187,717	$ 246,127

Accrued Expenses and Other Cu_3

Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Payables and Accruals [Abstract]
Employee compensation and related costs	$ 3,460	$ 7,022
Construction in process	2,494	3,182
Income taxes payable	454	288
Professional and consulting services	552	1,273
Deferred income received under partnerships	77
Other	1,708	1,356
Accrued expenses and other current liabilities	$ 8,745	$ 13,121

Government Grant (Details)

Government Grant (Details) $ in Millions, ₩ in Billions	1 Months Ended
	Dec. 31, 2022	Mar. 31, 2024 KRW (₩)	Mar. 31, 2024 USD ($)	Dec. 31, 2023 KRW (₩)	Dec. 31, 2023 USD ($)
Government Assistance [Abstract]
Government assistance, transaction duration	5 years
Government assistance, unearned government grant		₩ 12	$ 8.9	₩ 12	$ 9.3

Sponsor Earn-Out Liabilities -

Sponsor Earn-Out Liabilities - General Information (Details)	Feb. 02, 2022 $ / shares shares
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Sponsor Earn-Out Shares, shares issued (in shares) | shares	6,900,000
Common Class A
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Sponsor Earn-Out Shares, par value (in dollars per shares)	$ 0.0001
Common Class B
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Sponsor Earn-Out Shares, par value (in dollars per shares)	$ 0.0001

Sponsor Earn-Out Liabilities _2

Sponsor Earn-Out Liabilities - Transfer Restrictions and Forfeiture Terms (Details) $ / shares in Units, $ in Thousands	Feb. 02, 2022 D $ / shares	Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)
Derivative Instruments and Hedging Activities Disclosures [Line Items]
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
Fair Value, Recurring
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Sponsor Earn-Out liabilities | $		$ 3,291	$ 4,166
Fair Value, Inputs, Level 3 | Fair Value, Recurring
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Sponsor Earn-Out liabilities | $		$ 3,291	$ 4,166

Sponsor Earn-Out Liabilities _3

Sponsor Earn-Out Liabilities - Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	$ 4,166	$ 10,961
Change in fair value	(875)	(569)
Ending Balance	$ 3,291	$ 10,392
Fair Value, Liability, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income	Gain on change in fair value of Sponsor Earn-Out liabilities	Gain on change in fair value of Sponsor Earn-Out liabilities

Sponsor Earn-Out Liabilities _4

Sponsor Earn-Out Liabilities - Key Inputs (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2024 $ / shares Y	Dec. 31, 2023 $ / shares Y
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative Liability, Valuation Technique	us-gaap:ValuationTechniqueOptionPricingModelMember	us-gaap:ValuationTechniqueOptionPricingModelMember
Sponsor earn-out liability, price volatility, weighted-average, low end of range (as a percent)	78.20%	83.80%
Sponsor earn-out liability, price volatility, weighted-average, high end of range (as a percent)	89.20%	96.20%
Measurement Input, Expected Term
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Sponsor earn-out liability, measurement input | Y	3.1	3.1
Measurement Input, Risk Free Interest Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Sponsor earn-out liability, measurement input	0.0430	0.0404
Measurement Input, Price Volatility
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Sponsor earn-out liability, measurement input	0.850	0.910
Measurement Input, Expected Dividend Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Sponsor earn-out liability, measurement input	0	0
Measurement Input, Share Price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Sponsor earn-out liability, measurement input | $ / shares	1.68	1.83

Commitments and Contingencies (

Commitments and Contingencies (Details) $ in Millions	Mar. 31, 2024 USD ($)
Strategic Automotive Original Equipment Manufacturer Partner
Other Commitments [Line Items]
Joint development agreements, expenditures related to engineering efforts and purchases of related equipment, maximum	$ 35

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock-based Compensation Expense - Statement of Operations (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Stock-Based Compensation
Compensation expense	$ 4,784	$ 6,462
Research and Development Expense
Stock-Based Compensation
Compensation expense	1,451	1,847
General and Administrative Expense
Stock-Based Compensation
Compensation expense	$ 3,333	$ 4,615

Stock-Based Compensation - St_2

Stock-Based Compensation - Stock-based Compensation Expense - Award Type (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Stock-Based Compensation
Compensation expense	$ 4,784	$ 6,462
Earn-out Restricted Shares
Stock-Based Compensation
Compensation expense		2,135
Restricted Stock Units (RSUs)
Stock-Based Compensation
Compensation expense	3,085	1,961
Performance Stock Units
Stock-Based Compensation
Compensation expense	932	1,326
Restricted Stock Awards
Stock-Based Compensation
Compensation expense	491	930
Employee Stock Option
Stock-Based Compensation
Compensation expense	$ 276	$ 110

Stock-Based Compensation - Gene

Stock-Based Compensation - General Information (Details)	1 Months Ended
	Feb. 29, 2024 shares
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares, granted (in shares)	8,996,931
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares, granted (in shares)	3,280,083

Income Taxes - Effective Tax Ra

Income Taxes - Effective Tax Rate (Details)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Effective tax rate (as a percent)	(1.80%)	(0.90%)
Statutory federal income tax rate (as a percent)	21%	21%

Net Loss Per Share - Basic and

Net Loss Per Share - Basic and Diluted Net Income (Loss) Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Net Income (Loss) Available to Common Stockholders, Diluted [Abstract]
Net loss	$ (15,557)	$ (16,226)
Net loss attributable to common stockholders - basic	(15,557)	(16,226)
Net loss attributable to common stockholders - diluted	$ (15,557)	$ (16,226)
Weighted Average Number of Shares Outstanding, Diluted [Abstract]
Weighted-average shares of common stock outstanding, basic (in shares)	318,790,719	313,422,442
Weighted-average shares of common stock outstanding, diluted (in shares)	318,790,719	313,422,442
Earnings Per Share, Diluted [Abstract]
Net loss per share attributable to common stockholders - basic (in dollars per share)	$ (0.05)	$ (0.05)
Net loss per share attributable to common stockholders - diluted (in dollars per share)	$ (0.05)	$ (0.05)

Net Loss Per Share - Potentiall

Net Loss Per Share - Potentially Dilutive Securities (Details) - shares	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total	84,603,836	73,554,837
Escrowed Earn-out Shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total	27,690,978	27,690,978
Employee Stock Option
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total	12,381,133	18,203,903
Common Stock Warrants, Public Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total	9,199,947	9,199,947
Sponsor Earn-Out Shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total	5,520,000	5,520,000
Common Stock Warrants, Private Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total	5,013,333	5,013,333
Restricted Stock Units (RSUs)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total	16,525,573	2,789,984
Performance Stock Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total	6,812,398	2,116,942
Earn-out Restricted Shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total	908,700	1,929,140
Restricted Stock Awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total	551,774	1,090,610

Related-Party Transactions (Det

Related-Party Transactions (Details)	Mar. 31, 2024	Dec. 31, 2023
Director | General Motors | Minimum
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
	Mar. 31, 2024	Mar. 31, 2023
Pay vs Performance Disclosure
Net Income (Loss)	$ (15,557)	$ (16,226)

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Mar. 31, 2024
Jing Nealis [Member]
Trading Arrangements, by Individual
Material Terms of Trading Arrangement	On January 5, 2024, Jing Nealis (our Chief Financial Officer) terminated a Rule 10b5-1 plan that had been adopted on June 14, 2022 which provided for the sale of a number of shares of Class A common stock sufficient to cover satisfy minimum statutory withholding tax obligations upon vesting of a restricted share award granted on August 16, 2021.
Name	Jing Nealis
Title	Chief Financial Officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	June 14, 2022
Rule 10b5-1 Arrangement Terminated	true
Termination Date	January 5, 2024
Executive Officers [Member]
Trading Arrangements, by Individual
Material Terms of Trading Arrangement	On February 9, 2024, each of Qichao Hu (our Founder, Chairman and Chief Executive Officer), Jing Nealis (our Chief Financial Officer), Hong Gan (our Chief Science Officer), Kyle Pilkington (our Chief Legal Officer) and Gang “Daniel” Li (our Chief Manufacturing Officer, and collectively with Dr. Hu, Ms. Nealis, Dr. Gan, and Mr. Pilkington, the “Executive Officers”) entered into written stock selling plans in accordance with Rule 10b5-1 (the “Plans”) under the Exchange Act in connection with the sale of shares of Class A common stock underlying RSUs and PSUs granted to Dr. Hu, Ms. Nealis, Dr. Gan, Mr. Pilkington and Mr. Li on February 9, 2024. The Plans provide for the sale of only such number of shares necessary to satisfy minimum statutory withholding tax obligations arising from the vesting of such equity awards (with the RSUs vesting subject to continued service in three equal installments on each anniversary of the grant date, and the PSUs vesting subject to continued service and performance in one installment following a three-year performance period after the grant date), and, thus, the exact number of shares to be sold is unknown. Each Plan expires once all shares are sold to satisfy the applicable Executive Officer’s withholding tax obligations.
Name	Dr. Hu, Ms. Nealis, Dr. Gan, and Mr. Pilkington
Title	Executive Officers
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	February 9, 2024
Arrangement Duration	3 years