QuantumScape (QS) POS AM 17 May 21 Prospectus update (post-effective amendment) Financial data

Document and Entity Information

Document and Entity Information	3 Months Ended
	Mar. 31, 2021
Document And Entity Information [Line Items]
Document Type	POS AM
Amendment Flag	true
Entity Registrant Name	QUANTUMSCAPE CORPORATION
Amendment Description	POST-EFFECTIVE AMENDMENT NO. 3 TO FORM S-1
Entity Central Index Key	0001811414
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	85-0796578
Entity Address, Address Line One	1730 Technology Drive
Entity Address, City or Town	San Jose
Entity Address, State or Province	CA
Entity Address Postal Zip Code	95110
City Area Code	408
Local Phone Number	452-2000

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Current assets
Cash and cash equivalents	$ 762,341	$ 113,216	$ 22,822
Marketable securities	771,101	884,336	107,099
Prepaid expenses and other current assets	8,502	11,616	1,255
Total current assets	1,541,944	1,009,168	131,176
Property and equipment, net	59,533	43,696	25,492
Right-of-use lease asset	12,031	11,712	12,942
Other assets	2,829	2,193	2,774
Total assets	1,616,337	1,066,769	172,384
Current liabilities
Accounts payable	9,871	5,383	2,851
Accrued liabilities	4,160	2,701	1,307
Accrued compensation	5,355	2,391	1,112
Operating lease liability, short-term	1,465	1,220	1,080
Strategic premium, short-term	503	655	873
Total current liabilities	21,354	12,350	7,223
Operating lease liability, long-term	11,344	11,244	12,463
Convertible preferred stock warrant liabilities			1,860
Strategic premium, long-term and other liabilities			436
Assumed common stock warrant liabilities	288,039	689,699
Total liabilities	320,737	713,293	21,982
Commitments and contingencies
Redeemable non-controlling interest	1,694	1,704	1,710
Stockholders’ equity
Preferred stock, value
Common stock, value	39	36	24
Additional paid-in-capital	3,346,442	2,329,406	444,440
Accumulated other comprehensive (loss) income	143	(31)	90
Accumulated deficit	(2,052,718)	(1,977,639)	(295,862)
Total stockholders’ equity	1,293,906	351,772	148,692
Total liabilities, redeemable non-controlling interest and stockholders’ equity	$ 1,616,337	$ 1,066,769	$ 172,384

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash and cash equivalents	$ 762,341	$ 113,216	$ 22,822
Preferred stock, par value	$ 0.0001	$ 0.0001	$ 0.0001
Preferred stock, authorized	100,000,000	100,000,000	100,000,000
Preferred stock, shares issued	0	0	0
Preferred stock, outstanding	0	0	0
Common stock, par value		$ 0.0001
Common stock, authorized	1,250,000,000	1,250,000,000	1,250,000,000
Joint Venture
Cash and cash equivalents	$ 3,381	$ 3,406	$ 3,409
Class A Common Stock
Common stock, par value	$ 0.0001	$ 0.0001	$ 0.0001
Common stock, authorized	1,000,000,000	1,000,000,000	1,000,000,000
Common stock, issued	233,610,488	207,769,091	81,720,530
Common stock, outstanding	233,610,488	207,769,091	81,720,530
Class B Common Stock
Common stock, par value	$ 0.0001	$ 0.0001	$ 0.0001
Common stock, authorized	250,000,000	250,000,000	250,000,000
Common stock, issued	156,161,849	156,224,614	158,056,527
Common stock, outstanding	156,161,849	156,224,614	158,056,527

Consolidated Statements of Oper

Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Operating expenses:
Research and development	$ 29,465	$ 13,347	$ 65,103	$ 45,944
General and administrative	15,210	2,569	15,918	9,874
Total operating expenses	44,675	15,916	81,021	55,818
Loss from operations	(44,675)	(15,916)	(81,021)	(55,818)
Other (loss) income:
Interest expense			(20,765)	(94)
Interest income	247	538	1,093	3,608
Change in fair value of Series F convertible preferred stock tranche liabilities			(999,987)
Change in fair value of assumed common stock warrant liabilities	(30,800)		(581,863)
Other income	103		760	1,041
Total other (loss) income	(30,414)	538	(1,600,762)	4,555
Change in fair value of assumed common stock warrant liabilities	(30,764)		(20,765)	(94)
Net loss	(75,089)	(15,378)	(1,681,783)	(51,263)
Less: Net (loss) income attributable to non-controlling interest, net of tax of $0 for the years ended December 31, 2020 and 2019	(10)	(4)	(6)	20
Net loss attributable to common stockholders	(75,079)	(15,374)	(1,681,777)	(51,283)
Other comprehensive (loss) income:
Unrealized (loss) gain on marketable securities	174	315	(121)	121
Total comprehensive loss	(74,915)	(15,063)	(1,681,904)	(51,142)
Less: Comprehensive (loss) income attributable to non-controlling interest	(10)	(4)	(6)	20
Comprehensive loss attributable to common stockholders	$ (74,905)	$ (15,059)	$ (1,681,898)	$ (51,162)
Basic and Diluted net loss per share	$ (0.20)	$ (0.06)	$ (6.67)	$ (0.21)
Basic and Diluted weighted-average common shares outstanding	368,783,516	239,792,967	252,143,509	239,636,062

Consolidated Statements of Op_2

Consolidated Statements of Operations and Comprehensive Loss (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Income Statement [Abstract]
Net (loss) income attributable to non-controlling interest, tax	$ 0	$ 0	$ 0	$ 0

Consolidated Statements of Rede

Consolidated Statements of Redeemable Non-Controlling Interest and Stockholders' Equity - USD ($) $ in Thousands	Total	Series F Preferred Stock	Legacy Quantum Scape Series F Preferred Stock Purchase AgreementClass A Common Stock	Convertible Preferred Stock Tranche	Convertible Preferred Stock Warrants	Cumulative Effect, Period of Adoption, Adjustment	Previously Reported	Retroactive Application of Recapitalization	Common Stock	Common StockSeries F Preferred Stock	Common StockLegacy Quantum Scape Series F Preferred Stock Purchase AgreementClass A Common Stock	Common StockPreviously Reported	Common StockRetroactive Application of Recapitalization	Treasury StockPreviously Reported	Treasury StockRetroactive Application of Recapitalization	Additional Paid-In Capital	Additional Paid-In CapitalSeries F Preferred Stock	Additional Paid-In CapitalLegacy Quantum Scape Series F Preferred Stock Purchase AgreementClass A Common Stock	Additional Paid-In CapitalConvertible Preferred Stock Tranche	Additional Paid-In CapitalConvertible Preferred Stock Warrants	Additional Paid-In CapitalPreviously Reported	Additional Paid-In CapitalRetroactive Application of Recapitalization	Accumulated Deficit	Accumulated DeficitCumulative Effect, Period of Adoption, Adjustment	Accumulated DeficitPreviously Reported	Accumulated Other Comprehensive Gain (Loss)	Accumulated Other Comprehensive Gain (Loss)Previously Reported
Redeemable Convertible Preferred Stock, Beginning balance at Dec. 31, 2018							$ 405,575	$ (405,575)
Redeemable Convertible Preferred Stock, Beginning balance, Shares at Dec. 31, 2018							48,390,851	(48,390,851)
Beginning balance at Dec. 31, 2018	$ 191,230						$ (214,345)	$ 405,575	$ 24			$ 1	$ 23	$ (4,189)	$ 4,189	$ 437,320					$ 35,957	$ 401,363	$ (246,083)		$ (246,083)	$ (31)	$ (31)
Redeemable Non-Controlling, Beginning balance at Dec. 31, 2018	$ 1,690						1,690
Beginning balance, Shares at Dec. 31, 2018									239,158,653			11,075,476	228,083,177	438,191	(438,191)
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201602Member
Exercise of stock option	$ 394															394
Exercise of stock option, Shares	618,404								618,404
Stock-based compensation	$ 6,811															6,726							85
Beginning balance at Dec. 31, 2018						$ 1,419																		$ 1,419
Net loss	(51,283)																						(51,283)
Net loss, Redeemable Non-Controlling interest	20
Unrealized gain (loss) on marketable securities	121																									121
Ending balance at Dec. 31, 2019	148,692								$ 24							444,440							(295,862)			90
Redeemable Non-Controlling, Ending balance at Dec. 31, 2019	1,710						1,700
Ending balance at Dec. 31, 2019	148,692								$ 24							444,440							(295,862)			90
Ending balance, Shares at Dec. 31, 2019									239,777,057
Exercise of stock option	13															13
Exercise of stock option, Shares									20,109
Stock-based compensation	2,197															2,197
Net loss	(15,374)																						(15,374)
Net loss, Redeemable Non-Controlling interest	(4)
Unrealized gain (loss) on marketable securities	315																									315
Redeemable Non-Controlling, Ending balance at Mar. 31, 2020	1,706
Ending balance at Mar. 31, 2020	135,843								$ 24							446,650							(311,236)			405
Ending balance, Shares at Mar. 31, 2020									239,797,166
Beginning balance at Dec. 31, 2019	148,692								$ 24							444,440							(295,862)			90
Redeemable Non-Controlling, Beginning balance at Dec. 31, 2019	1,710						1,700
Beginning balance, Shares at Dec. 31, 2019									239,777,057
Issuance of Series F preferred stock, net of issuance costs of $11.5 million, and settlement of associated convertible preferred stock tranche liability		$ 660,933								$ 3							$ 660,930
Issuance of stock, net of issuance costs, and settlement of associated convertible preferred stock tranche liability, Shares										28,616,093
Issuance of Class A Common Stock pursuant to Legacy Quantum Scape Series F Preferred Stock Purchase Agreement, net of issuance costs of $0.2 million			$ 99,800								$ 1							$ 99,799
Issuance of common stock, net of issuance costs, shares											15,221,334
Business Combination, net of redemptions and equity issuance costs of $53.0 million (Restated)	568,603								$ 8							568,595
Business Combination, net of redemptions and equity issuance costs, Shares (Restated)									78,734,745
Reclassification of Legacy QuantumScape liabilities				$ 515,394	$ 22,625														$ 515,394	$ 22,625
Exercise of stock option	$ 599															599
Exercise of stock option, Shares	646,016								646,016
Exercise of warrants, Shares									998,460
Stock-based compensation	$ 17,024															17,024
Beginning balance at Dec. 31, 2019	148,692								$ 24							444,440							(295,862)			90
Net loss	(1,681,777)						(1,099,914)																(1,681,777)
Net loss, Redeemable Non-Controlling interest	(6)
Unrealized gain (loss) on marketable securities	(121)						(121)																			(121)
Ending balance at Dec. 31, 2020	351,772								36							2,329,406							(1,977,639)			(31)
Redeemable Non-Controlling, Ending balance at Dec. 31, 2020	1,704						1,704
Ending balance at Dec. 31, 2020	351,772						$ 1,041,471		$ 36							2,329,406							(1,977,639)			(31)
Ending balance, Shares at Dec. 31, 2020									363,993,705
Issuance of Class A Common Stock pursuant to Legacy Quantum Scape Series F Preferred Stock Purchase Agreement, net of issuance costs of $0.2 million	462,926								$ 1							462,925
Issuance of common stock, net of issuance costs, shares									11,960,000
Exercise of stock option	$ 880								$ 1							879
Exercise of stock option, Shares	2,884,549								2,884,549
Exercise of warrants	$ 541,557								$ 1							541,556
Exercise of warrants, Shares									9,489,764
Stock-based compensation	11,676															11,676
Net loss	(75,079)																						(75,079)
Net loss, Redeemable Non-Controlling interest	(10)
Unrealized gain (loss) on marketable securities	174																									174
Redeemable Non-Controlling, Ending balance at Mar. 31, 2021	1,694
Ending balance at Mar. 31, 2021	$ 1,293,906								$ 39							$ 3,346,442							$ (2,052,718)			$ 143
Shares issued upon vesting of restricted stock units									1,444,319
Ending balance, Shares at Mar. 31, 2021									389,772,337

Consolidated Statements of Re_2

Consolidated Statements of Redeemable Non-Controlling Interest and Stockholders' Equity (Parenthetical) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Redemptions and equity issuance costs		$ 53,000,000
Series F Preferred Stock
Stock issuance costs		11,500,000
Class A Common Stock
Stock issuance costs		$ 200,000
Common Stock
Stock issuance costs	$ 15,500,000

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Operating activities
Net loss	$ (75,089)	$ (15,378)	$ (1,681,783)	$ (51,263)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	2,201	1,442	7,506	5,577
Amortization of right-of-use assets	371	300	1,229	1,159
Amortization of premiums and accretion of discounts on marketable securities	2,410	(53)	1,201	(1,964)
Amortization of strategic premium	(151)	(164)	(655)	(873)
Gain on property and equipment disposals	(104)		3	(90)
Stock-based compensation expense	11,676	2,197	17,024	6,811
Change in fair value of convertible preferred stock warrant liabilities	30,764		20,765	94
Change in fair value of convertible preferred stock tranche liabilities			999,865
Change in fair value of assumed common stock warrant liabilities	30,800		581,863
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	2,479	(165)	(9,648)	(550)
Accounts payable, accrued liabilities and accrued compensation	4,252	600	2,447	319
Operating lease liability	(345)	(260)	(1,080)	(951)
Net cash used in operating activities	(21,536)	(11,481)	(61,263)	(41,731)
Investing activities
Purchases of property and equipment	(13,269)	(4,934)	(24,093)	(9,846)
Proceeds from disposal of property and equipment	108
Proceeds from maturities of marketable securities	111,000	32,000	113,006	239,500
Purchases of marketable securities			(891,561)	(196,353)
Net cash (used in) provided by investing activities	97,839	27,066	(802,648)	33,301
Financing activities
Proceeds from exercise of stock options	880	13	599	394
Net proceeds from warrant exercised	109,133
Payment of Business Combination share issuance costs	(1,016)
Proceeds from issuance of Series F preferred stock, net of issuance costs			176,462
Proceeds from issuance of Class A Common Stock pursuant to Legacy QuantumScape Series F Preferred Stock Purchase Agreement, net of issuance costs	463,825		99,800
Business Combination, net of issuance costs paid			676,863
Net cash provided by financing activities	572,822	13	953,724	394
Net increase (decrease) in cash, cash equivalents and restricted cash	649,125	15,598	89,813	(8,036)
Cash, cash equivalents and restricted cash at beginning of period	115,409	25,596	25,596	33,632
Cash, cash equivalents and restricted cash at end of period	764,534	41,194	115,409	25,596
Supplemental disclosure of cash flow information
Purchases of property and equipment, accrued but not paid	8,944	$ 1,423	4,170	$ 2,547
Business Combination transaction costs, accrued but not paid			1,016
Net assets assumed from Business Combination			$ 592
Common stock issuance costs, accrued but not paid	899
Fair value of assumed common stock warrants exercised	$ 432,424

Cash, Cash Equivalents and Rest

Cash, Cash Equivalents and Restricted Cash by Category - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement Of Cash Flows [Abstract]
Cash and cash equivalents	$ 762,341	$ 113,216	$ 39,001	$ 22,822
Other assets	2,829	2,193	2,193	2,774
Total cash, cash equivalents and restricted cash	$ 764,534	$ 115,409	$ 41,194	$ 25,596	$ 33,632

Organization

Organization	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Organization	Note 1. Organization On November 25, 2020 (the “Closing Date”), Kensington Capital Acquisition Corp. (“Kensington”), a special purpose acquisition company, consummated the Business Combination Agreement (the “Business Combination Agreement”) dated September 2, 2020, by and among Kensington, Kensington Merger Sub Corp., a Delaware corporation and wholly owned subsidiary of Kensington (“Merger Sub”), and QuantumScape Battery, Inc., a Delaware corporation (f/k/a QuantumScape Corporation and f/k/a QuantumScape Subsidiary, Inc.) (“Legacy QuantumScape”). Pursuant to the terms of the Business Combination Agreement, a business combination between Kensington and Legacy QuantumScape was effected through the merger of Merger Sub with and into Legacy QuantumScape, with Legacy QuantumScape surviving as the surviving company and as a wholly-owned subsidiary of Kensington (the “Merger” and, collectively with the other transactions described in the Business Combination Agreement, the “Business Combination”). On the Closing Date, Kensington changed its name to QuantumScape Corporation, (the “Company”). The Company is focused on the development and commercialization of its solid-state lithium-metal batteries. Planned principal operations have not yet commenced. As of March 31, 2021, the Company has not derived revenue from its principal business activities. Beginning in March 2020, the COVID-19 COVID-19	1. Nature of Business Organization On November 25, 2020 (the “Closing Date”), Kensington Capital Acquisition Corp. (“Kensington”), a special purpose acquisition company, consummated the Business Combination Agreement (the “Business Combination Agreement”) dated September 2, 2020, by and among Kensington, Kensington Merger Sub Corp., a Delaware corporation and wholly owned subsidiary of Kensington (“Merger Sub”), and QuantumScape Battery, Inc., a Delaware corporation (f/k/a QuantumScape Corporation and f/k/a QuantumScape Subsidiary, Inc.) (“Legacy QuantumScape”). Pursuant to the terms of the Business Combination Agreement, a business combination between Kensington and Legacy QuantumScape was effected through the merger of Merger Sub with and into Legacy QuantumScape, with Legacy QuantumScape surviving as the surviving company and as a wholly-owned subsidiary of Kensington (the “Merger” and, collectively with the other transactions described in the Business Combination Agreement, the “Business Combination”). On the closing date, Kensington changed its name to QuantumScape Corporation, (the “Company”). The Company is focused on the development and commercialization of its solid-state lithium-metal batteries. Planned principal operations have not yet commenced. As of December 31, 2020, the Company has not derived revenue from its principal business activities. Beginning in March 2020, the COVID-19 COVID-19

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Note 2. Summary of Significant Accounting Policies Basis of Presentation The Company’s unaudited condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”) as determined by the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) and pursuant to the regulations of the U.S. Securities and Exchange Commission (“SEC”). Pursuant to the Business Combination Agreement, the merger between Merger Sub and Legacy QuantumScape was accounted for as a reverse recapitalization in accordance with U.S. GAAP (the “Reverse Recapitalization”). Under this method of accounting, Kensington was treated as the “acquired” company and Legacy QuantumScape is treated as the acquirer for financial reporting purposes. Accordingly, for accounting purposes, the Reverse Recapitalization was treated as the equivalent of Legacy QuantumScape issuing stock for the net assets of Kensington, accompanied by a recapitalization. The net assets of Kensington are stated at historical cost, with no goodwill or other intangible assets recorded. Legacy QuantumScape was determined to be the accounting acquirer based on the following predominant factors: • Legacy QuantumScape’s shareholders have the largest portion of voting rights in the Company; • the Company’s Board of Directors (the “Board”) and management are primarily composed of individuals associated with Legacy QuantumScape; and • Legacy QuantumScape was the larger entity based on historical operating activity and Legacy QuantumScape has the larger employee base at the time of the Business Combination. The consolidated assets, liabilities and results of operations prior to the Reverse Recapitalization are those of Legacy QuantumScape. The shares and corresponding capital amounts and losses per share, prior to the Business Combination, have been retroactively restated based on shares reflecting the Exchange Ratio (as defined below) established in the Business Combination. Use of Estimates The preparation of the condensed consolidated financial statements in accordance with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of commitments and contingencies at the date of the financial statements as well as reported amounts of expenses during the reporting periods. Estimates made by the Company include, but are not limited to, those related to the valuation of common stock prior to the Business Combination, valuation of convertible preferred stock warrants, and valuation of convertible preferred stock tranche liabilities, among others. The Company bases these estimates on historical experience and on various other assumptions that it believes are reasonable under the circumstances, the results of which form the basis for making judgments about the carrying amounts of assets and liabilities that are not readily apparent from other sources. Actual results could differ materially from those estimates. Unaudited Interim Condensed Consolidated Financial Statements The accompanying interim condensed consolidated balance sheet as of March 31, 2021, the interim condensed consolidated statements of redeemable non-controlling These unaudited interim condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and the related notes included in the Company’s audited annual consolidated financial statements for the year ended December 31, 2020 included in the Company’s Annual Report on Form 10-K/A Principles of Consolidation The Company’s policy is to consolidate all entities that it controls by ownership of a majority of the outstanding voting stock. In addition, the Company consolidates entities that meet the definition of a variable interest entity (“VIE”) for which the Company is the related party most closely associated with and is the primary beneficiary. The primary beneficiary is the party who has the power to direct the activities of a VIE that most significantly impact the entity’s economic performance and who has an obligation to absorb losses of the entity or a right to receive benefits from the entity that could potentially be significant to the entity. For consolidated entities that are less than wholly owned, the third party’s holding of an equity interest is presented as redeemable non-controlling Non-Controlling non-controlling non-controlling The Company was a single-legal entity prior to becoming a partner with Volkswagen in QSV Operations LLC (“QSV”). As noted in the section titled “ Joint Venture and Redeemable Non-Controlling Joint Venture and Redeemable Non-Controlling On June 18, 2018, QSV was incorporated as a limited liability company. Volkswagen Group of America, Inc. (“VWGoA”), Volkswagen Group of America Investments, LLC (“VGA”) and QuantumScape executed a Joint Venture Agreement (“JVA”), effective September 2018, with the goal of jointly establishing a manufacturing facility in the United States to produce the pilot line of the Company’s product through QSV. In connection with this agreement, the parties also have entered into two operating agreements: (i) the Limited Liability Company Agreement of QSV to govern the respective rights and obligations as Members of QSV and (ii) the Common IP License Agreement for the Company to license certain intellectual property rights pertaining to automotive battery cells as defined in the JVA to VWGoA, VGA and QSV. Volkswagen is a related party stockholder (13.7% and 13.2% voting interest holder of the Company as of March 31, 2021 and December 31, 2020, respectively). Upon the effectiveness of the JVA, each party contributed $1.7 million in cash to capitalize QSV in exchange for 50% equity interests. The joint venture is considered a VIE with a related party and therefore the related party whose business is more closely related to the planned operations of the joint venture is required to consolidate the operations. The Company determined its operations were most closely aligned with the operations of the joint venture and therefore has consolidated the results of QSV’s operations in its Condensed Consolidated Balance Sheets, Condensed Consolidated Statements of Operations and Comprehensive Loss and Condensed Consolidated Statements of Redeemable Non-Controlling The Company classifies non-controlling 480-10-S99-3A, Classification and Measurement of Redeemable Securities 480-10-S99-3A”). non-controlling non-controlling non-controlling non-controlling Concentrations of Credit Risk Financial instruments that potentially subject the Company to credit risk consist principally of cash and cash equivalents and marketable securities. As of March 31, 2021 and December 31, 2020, approximately $755.8 million and $12.2 million of our total cash and cash equivalents and marketable securities, are held in a U.S. government money market fund, and $771.1 million and $977.3 million are invested in U.S. government and agency securities, respectively. The Company seeks to mitigate its credit risk with respect to cash and cash equivalents and marketable securities by making deposits with large, reputable financial institutions and investing in high credit rated shorter-term instruments. Cash and Cash Equivalents and Restricted Cash Management considers all highly liquid investments with an insignificant interest rate risk and original maturities of three months or less to be cash equivalents. Restricted cash, if the date of availability or disbursement is longer than one year and the balances are maintained under an agreement that legally restricts the use of such funds, is not included within cash and cash equivalents and is reported within other assets. Restricted cash is comprised of $2.2 million, of which $2.0 million is pledged as a form of security for the Company’s lease agreement for its headquarters facility and $0.2 million as collateral for a commercial letter of credit issued to an equipment supplier as of March 31, 2021. As of December 31, 2020, restricted cash was $2.2 million. Marketable Securities The Company’s investment policy is consistent with the definition of available-for-sale These debt securities are carried at estimated fair value with unrealized holding gains and losses included in other comprehensive loss in stockholders’ equity until realized. Gains and losses on marketable security transactions are reported on the specific-identification method. Dividend and interest income are recognized when earned. Fair Value Measurement The Company applies fair value accounting for all financial assets and liabilities measured on a recurring and nonrecurring basis. Fair value is defined as an exit price, representing the amount 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. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or a liability. The accounting guidance established a fair value hierarchy based on three levels of inputs, of which the first two are considered observable and the last unobservable, used to determine the fair value of its financial instruments. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. • Level 1 – Quoted prices in active markets for identical assets or liabilities that the entity has the ability to access. • Level 2 – Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets and liabilities. • Level 3 – Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets and liabilities. Property and Equipment Property and equipment are stated at cost, less accumulated depreciation. Depreciation is computed using the straight-line method over the estimated useful life of the related asset. The estimated useful lives of assets are as follows: Computers and hardware 3 years Furniture and fixtures 7 years Lab equipment 5 years Leasehold improvements Shorter of the lease term (including estimated renewals) or the estimated useful lives of the improvements Maintenance and repairs are charged to expense as incurred, and improvements are capitalized. When assets are retired or otherwise disposed of, the cost and accumulated depreciation are removed from the accounts, and any resulting gain or loss is reflected in the accompanying statements of operations and comprehensive loss in the period realized. Impairment of Long-Lived Assets The Company evaluates the carrying value of long-lived assets when indicators of impairment exist. The carrying value of a long-lived asset is considered impaired when the estimated separately identifiable, undiscounted cash flows from such an asset are less than the carrying value of the asset. In that event, a loss is recognized based on the amount by which the carrying value exceeds the fair value of the long-lived asset. Fair value is determined primarily using the estimated cash flows discounted at a rate commensurate with the risk involved. There were no material impairment charges in any of the periods presented. Leases The Company accounts for its leases under ASC 842, Leases right-of-use right-of-use right-of-use In calculating the right-of-use non-lease Convertible Preferred Stock Prior to the Business Combination, the Company recorded shares of convertible preferred stock at their respective fair values on the dates of issuance, net of issuance costs. The Company applied the guidance in ASC 480-10-S99-3A All convertible preferred stock previously classified as temporary equity was retroactively adjusted, converted into Class A and Class B Common Stock, and reclassified to permanent as a result of the Business Combination. Convertible preferred stock converted into shares of Legacy QuantumScape Class A and Class B Common Stock and were immediately exchanged for Class A and Class B Common Stock of the Company, as described in Note 4. In March 2016 and March 2017, Legacy QuantumScape issued shares of Legacy QuantumScape Series D convertible preferred stock to two new strategic investors and to an existing strategic investor for net proceeds of $59.7 million. Legacy QuantumScape determined that the Legacy QuantumScape Series D convertible preferred stock share purchase agreements with these investors contained strategic terms as all of these investors had strategic interests in the Company’s technology and negotiated specific strategic terms expected to benefit these new investors, over and above the value that would be expected to be realized from the equity investment itself. Thus, the sale of the Legacy QuantumScape Series D convertible preferred stock to these investors reflected a higher price (“strategic premium”) than what a market participant who did not receive these strategic benefits would be willing to pay. Legacy QuantumScape allocated the net proceeds from these investors between the Legacy QuantumScape Series D convertible preferred stock and the strategic premium resulting in a strategic premium of $7.9 million which it recorded as a deferred liability on the balance sheet. The strategic premium is considered akin to payment for research and development efforts. Legacy QuantumScape’s accounting policy is to record research and development effort payments as contra research and development and recorded the benefits (amortization of the strategic premium) over the estimated period of the development agreements with the investors which is re-assessed For the three months ended March 31, 2021 and 2020, the Company recorded amortization of $0.2 million and $0.2 million, respectively. Free-Standing Convertible Preferred Stock Warrants Liability Free-standing warrants issued by Legacy QuantumScape for the purchase of shares of its convertible preferred stock were classified as liabilities on the accompanying balance sheets at fair value using an Option-Pricing Model (“OPM”). Prior to the Business Combination, the liability recorded was adjusted for changes in the fair value at each reporting date and recorded as interest expense in the accompanying Condensed Consolidated Statements of Operations and Comprehensive Loss. As a result of the Business Combination, the Legacy QuantumScape warrants each converted into a warrant to purchase shares of the Company’s Class A Common Stock converted at the Exchange Ratio (as described below). The Company determined the warrants to be equity classified and the fair value of the warrants upon consummation of the Business Combination, as adjusted based on the price of the underlying Class A Common Stock, was reclassified to additional paid-in Assumed Common Stock Warrants Liability The Company assumed 11,499,989 public warrants (the “Public Warrants”) and 6,650,000 private placement warrants (the “Private Placement Warrants”, and the Public Warrants together with the Private Placement Warrants, the “Assumed Common Stock Warrants”) upon the Business Combination, all of which were issued in connection with Kensington’s initial public offering (other than 75,000 Private Placement Warrants of which that were issued in connection with the closing of the Business Combination, which are referred to as the Working Capital Warrants) and entitle each holder to purchase one share of Class A Common Stock at an exercise price of at $11.50 per share. As of March 31, 2021, 2,010,225 Public Warrants and 6,650,000 Private Placement Warrants are outstanding. The Public Warrants are publicly traded and are exercisable for cash unless certain conditions occur, such as the failure to have an effective registration statement related to the shares issuable upon exercise or redemption by the Company under certain conditions, at which time the warrants may be cashless exercised. The Private Placement Warrants are transferable, assignable or salable in certain limited exceptions. The Private Placement Warrants are exercisable for cash or on a cashless basis, at the holder’s option, and are non-redeemable The Company evaluated the Assumed Common Stock Warrants under ASC 815-40, Derivatives and Hedging—Contracts in Entity’s Own Equity (“ASC 815-40”) Segments Operating segments are defined as components of an entity for which separate financial information is available and that is regularly reviewed by the Chief Operating Decision Maker (“CODM”) in deciding how to allocate resources to an individual segment and in assessing performance. The Company’s CODM is its Chief Executive Officer. The Company has determined that it operates in one operating segment and one reportable segment, as the CODM reviews financial information presented on a consolidated basis for purposes of making operating decisions, allocating resources, and evaluating financial performance. Research and Development Cost Costs related to research and development are expensed as incurred. Stock-Based Compensation The Company measures and recognizes compensation expense for all stock-based awards made to employees, directors, and non-employees, The fair value of options granted is estimated on the grant date using the Black-Scholes option valuation model. This valuation model for stock-based compensation expense requires the Company to make assumptions and judgments about the variables used in the calculation, including the expected term (weighted-average period of time that the options granted are expected to be outstanding), the volatility of the Company’s common stock, and an assumed risk-free interest rate. The Company accounts for forfeitures when they occur. The Company uses the simplified calculation of the expected life, which takes into consideration the grant’s contractual life and vesting period and assumes that all options will be exercised between the vesting date and the contractual term of the option. No awards have been issued with a market condition or other non-standard Given the lack of public market for the Company’s common stock prior to the Business Combination and the Company’s minimal history as a public company subsequent to the Business Combination, the estimate for volatility is based on an average of the historical volatilities of the common stock of several entities with characteristics similar to those of the Company. Since these comparable companies operate in the same industry segment, the Company expects that it would share similar characteristics, such as risks profiles, volatility, capital intensity, clientele, and market growth patterns and drivers. The risk-free rate is based on the U.S. Treasury yield curve in effect at the time of grant for periods corresponding with the expected life of the option. The Company estimates the fair value of restricted stock units based on the closing price of the Company’s common stock on the date of grant. Income Taxes The Company accounts for income taxes under an asset and liability approach. Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes and operating loss carryforwards, measured by applying currently enacted tax laws. Valuation allowances are provided when necessary to reduce net deferred tax assets to an amount that is more likely than not to be realized. The Company recognizes tax liabilities based upon its estimate of whether, and the extent to which, additional taxes will be due when such estimates are more likely than not to be sustained. An uncertain income tax position will not be recognized if it has less than a 50% likelihood of being sustained. The Company has no provision for income taxes for the three months ended March 31, 2021 and 2020. The Company has no current tax expense from losses and no deferred expense from the valuation allowance. The Company’s effective tax rate differs from the U.S. statutory rate primarily due a valuation allowance against its net deferred tax assets as it more likely than not that some or all of the deferred tax assets will not be realized. Comprehensive Income or Loss The Company’s comprehensive income or loss consists of net income or loss and other comprehensive loss. Unrealized gains or losses on available-for-sale Net Loss per Share of Common Stock Basic net loss per share is computed by dividing the net loss by the weighted-average number of shares of common stock outstanding during the period. Diluted earnings per share adjusts basic earnings per share for the potentially dilutive impact of stock options and warrants. As the Company has reported losses for all periods presented, all potentially dilutive securities including stock options and warrants, are antidilutive and accordingly, basic net loss per share equals diluted net loss per share.	2. Summary of Significant Accounting Policies Basis of Presentation The Company’s consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”) as determined by the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) and pursuant to the regulations of the U.S. Securities and Exchange Commission (“SEC”). Pursuant to the Business Combination Agreement, the merger between Merger Sub and Legacy QuantumScape was accounted for as a reverse recapitalization in accordance with U.S. GAAP (the “Reverse Recapitalization”). Under this method of accounting, Kensington was treated as the “acquired” company and Legacy QuantumScape is treated as the acquirer for financial reporting purposes. Accordingly, for accounting purposes, the Reverse Recapitalization was treated as the equivalent of Legacy QuantumScape issuing stock for the net assets of Kensington, accompanied by a recapitalization. The net assets of Kensington are stated at historical cost, with no goodwill or other intangible assets recorded. Legacy QuantumScape was determined to be the accounting acquirer based on the following predominant factors: • Legacy QuantumScape’s shareholders have the largest portion of voting rights in the Company; • the Board and Management are primarily composed of individuals associated with Legacy QuantumScape; and • Legacy QuantumScape was the larger entity based on historical operating activity and Legacy QuantumScape has the larger employee base at the time of the Business Combination. The consolidated assets, liabilities and results of operations prior to the Reverse Recapitalization are those of Legacy QuantumScape. The shares and corresponding capital amounts and losses per share, prior to the Business Combination, have been retroactively restated based on shares reflecting the exchange ratio established in the Business Combination. Immaterial Adjustments The Company made an immaterial correcting adjustment (the “correcting adjustment”) to its Consolidated Balance Sheet and Consolidated Statement of Redeemable Non-controlling non-controlling non-controlling Use of Estimates The preparation of financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of commitments and contingencies at the date of the financial statements as well as reported amounts of expenses during the reporting periods. Estimates made by the Company include, but are not limited to, those related to the valuation of common stock prior to the Business Combination, valuation of convertible preferred stock warrants, and valuation of convertible preferred stock tranche liabilities, among others. The Company bases these estimates on historical experience and on various other assumptions that it believes are reasonable under the circumstances, the results of which form the basis for making judgments about the carrying amounts of assets and liabilities that are not readily apparent from other sources. Actual results could differ materially from those estimates. Principles of Consolidation The Company’s policy is to consolidate all entities that it controls by ownership of a majority of the outstanding voting stock. In addition, the Company consolidates entities that meet the definition of a variable interest entity (“VIE”) for which the Company is the related party most closely associated with and is the primary beneficiary. The primary beneficiary is the party who has the power to direct the activities of a VIE that most significantly impact the entity’s economic performance and who has an obligation to absorb losses of the entity or a right to receive benefits from the entity that could potentially be significant to the entity. For consolidated entities that are less than wholly owned, the third party’s holding of an equity interest is presented as Redeemable non-controlling Non-Controlling non-controlling non-controlling The Company was a single-legal entity prior to becoming a partner with Volkswagen in QSV Operations LLC (the “JV entity”). As noted in “Joint Venture” discussion, the Company determined the JV entity was a VIE for which it was required to consolidate the operations upon its formation in 2018. The Company continued to consolidate the operations of the JV entity in 2020 as the determination of the variable interest entity has not changed. Joint Venture and Redeemable Non-Controlling On June 18, 2018, the JV entity was incorporated as a limited liability company. Volkswagen Group of America, Inc. (“VWGoA”), Volkswagen Group of America Investments, LLC (“VGA”) and QuantumScape executed a Joint Venture Agreement (“JVA”), effective September 2018, with the goal of jointly establishing a manufacturing facility in the United States to produce the pilot line of the Company’s product through the JV entity. Volkswagen is a related party stockholder (13.2% and 13.1% voting interest holder of the Company as of December 31, 2020 and December 31, 2019, respectively). Upon the effectiveness of the JVA, each party contributed $1.7 million in cash to capitalize the JV entity in exchange for 50% equity interests. The joint venture is considered a variable interest entity with a related party and therefore the related party whose business is more closely related to the planned operations of the joint venture is required to consolidate the operations. The Company determined its operations were most closely aligned with the operations of the joint venture and therefore has consolidated the results of the JV entity’s operations in its Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Loss and Consolidated Statements of Redeemable Non-Controlling The Company classifies non-controlling 480-10-S99-3A, 480-10-S99-3A”). non-controlling non-controlling non-controlling non-controlling Concentrations of Credit Risk Financial instruments that potentially subject the Company to credit risk consist principally of cash and cash equivalents, of which $12.2 million is held in a US government Money Market fund and marketable securities, of which $977.3 million is invested in US government and agency securities. The Company seeks to mitigate its credit risk with respect to cash and cash equivalents and marketable securities by making deposits with large, reputable financial institutions and investing in high credit rated shorter-term instruments. Cash and Cash Equivalents and Restricted Cash Management considers all highly liquid investments with an insignificant interest rate risk and original maturities of three months or less to be cash equivalents. Restricted cash, if the date of availability or disbursement is longer than one year and the balances are maintained under an agreement that legally restricts the use of such funds, is not included within cash and cash equivalents and is reported within other assets. Restricted cash is comprised of $2.2 million, of which $2.0 million is pledged as a form of security for the Company’s facility lease agreement and $0.2 million as collateral for a commercial letter of credit issued to an equipment supplier as of December 31, 2020. As of December 31, 2019, restricted cash was $2.8 million. Marketable Securities The Company’s investment policy is consistent with the definition of available-for-sale These debt securities are carried at estimated fair value with unrealized holding gains and losses included in other comprehensive loss in stockholders’ deficit until realized. Gains and losses on marketable security transactions are reported on the specific-identification method. Dividend and interest income are recognized when earned. Fair Value Measurement The Company applies fair value accounting for all financial assets and liabilities measured on a recurring and nonrecurring basis. Fair value is defined as an exit price, representing the amount 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. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or a liability. The accounting guidance established a fair value hierarchy based on three levels of inputs, of which the first two are considered observable and the last unobservable, used to determine the fair value of its financial instruments. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. • Level 1 – Quoted prices in active markets for identical assets or liabilities that the entity has the ability to access. • Level 2 – Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets and liabilities. • Level 3 – Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets and liabilities. Property and Equipment Property and equipment are stated at cost, less accumulated depreciation. Depreciation is computed using the straight-line method over the estimated useful life of the related asset. The estimated useful lives of assets are as follows: Computers and hardware 3 years Furniture and fixtures 7 years Lab equipment 5 years Building and improvements 25 years Leasehold improvements Shorter of the lease term (including estimated renewals) or the estimated useful lives of the improvements Maintenance and repairs are charged to expense as incurred, and improvements are capitalized. When assets are retired or otherwise disposed of, the cost and accumulated depreciation are removed from the accounts, and any resulting gain or loss is reflected in the accompanying statements of operations and comprehensive loss in the period realized. Impairment of Long-Lived Assets The Company evaluates the carrying value of long-lived assets when indicators of impairment exist. The carrying value of a long-lived asset is considered impaired when the estimated separately identifiable, undiscounted cash flows from such an asset are less than the carrying value of the asset. In that event, a loss is recognized based on the amount by which the carrying value exceeds the fair value of the long-lived asset. Fair value is determined primarily using the estimated cash flows discounted at a rate commensurate with the risk involved. There were no material impairment charges in any of the periods presented. Leases The Company accounts for its leases under ASC 842, Leases. Under this guidance, lessees classify arrangements meeting the definition of a lease as operating or financing leases, and leases are recorded on the Consolidated Balance Sheet as both a right-of-use right-of-use right-of-use In calculating the right-of-use non-lease Convertible Preferred Stock Prior to the Business Combination, the Company recorded shares of convertible preferred stock at their respective fair values on the dates of issuance, net of issuance costs. The Company applied the guidance in ASC 480-10-S99-3A All convertible preferred stock previously classified as temporary equity was retroactively adjusted, converted into Class A and Class B Common Stock, and reclassified to permanent as a result of the Business Combination. Convertible preferred stock converted into shares of Legacy QuantumScape Class A and Class B Common Stock and were immediately exchanged for Class A and Class B Common Stock of the Company, see Note 6. In March 2016 and March 2017, Legacy QuantumScape issued shares of Legacy QuantumScape Series D convertible preferred stock to two new strategic investors and to an existing strategic investor for net proceeds of $59.7 million. Legacy QuantumScape determined that the Legacy QuantumScape Series D convertible preferred stock share purchase agreements with these investors contained strategic terms as all of these investors had strategic interests in the Company’s technology and negotiated specific strategic terms expected to benefit these new investors, over and above the value that would be expected to be realized from the equity investment itself. Thus, the sale of the Legacy QuantumScape Series D convertible preferred stock to these investors reflected a higher price (“strategic premium”) than what a market participant who did not receive these strategic benefits would be willing to pay. Legacy QuantumScape allocated the net proceeds from these investors between the Legacy QuantumScape Series D convertible preferred stock and the strategic premium resulting in a strategic premium of $7.9 million which it recorded as a deferred liability on the balance sheet. The strategic premium is considered akin to payment for research and development efforts. Legacy QuantumScape’s accounting policy is to record research and development effort payments as contra research and development and recorded the benefits (amortization of the strategic premium) over the estimated period of the development agreements with the investors which is re-assessed For the years ended December 31, 2020 and December 31, 2019, the Company recorded amortization of $0.7 million and $0.9 million, respectively. Free-Standing Convertible Preferred Stock Warrants Liability Free-standing warrants issued by Legacy QuantumScape for the purchase of shares of its convertible preferred stock were classified as liabilities on the accompanying balance sheets at fair value using an Option-Pricing Model (“OPM”). Prior to the Business Combination, the liability recorded was adjusted for changes in the fair value at each reporting date and recorded as interest expense in the accompanying Consolidated Statements of Operations and Comprehensive Loss. As a result of the Business Combination, the Legacy QuantumScape warrants converted into a warrant to purchase shares of the Company’s common stock converted at the Exchange Ratio. The Company determined the warrants to be equity classified and the fair value of the warrants upon consummation of the Business Combination, as adjusted based on the price of the underlying common stock, was reclassified to additional paid-in Assumed Common Stock Warrants Liability The Company assumed 11,499,989 Public Warrants and 6,650,000 Private Placement Warrants upon the Business Combination, all of which were issued in connection with Kensington’s initial public offering (other than 75,000 Private Placement Warrants of which that were issued in connection with the closing of the Business Combination) and entitle the holder to purchase one share of Class A Common Stock at an exercise price of at $11.50 per share. All of the Assumed Common Stock Warrants remained outstanding as of December 31, 2020. The Public Warrants are publicly traded and are exercisable for cash unless certain conditions occur, such as the failure to have an effective registration statement related to the shares issuable upon exercise or redemption by the Company under certain conditions, at which time the warrants may be cashless exercised. The Private Placement Warrants are transferable, assignable or salable in certain limited exceptions. The Private Placement Warrants are exercisable for cash or on a cashless basis, at the holder’s option, and are non-redeemable The Company evaluated the Assumed Common Stock Warrants under ASC 815-40, Derivatives and Hedging—Contracts in Entity’s Own Equity (“ASC 815-40”) Segments Operating segments are defined as components of an entity for which separate financial information is available and that is regularly reviewed by the Chief Operating Decision Maker (“CODM”) in deciding how to allocate resources to an individual segment and in assessing performance. The Company’s CODM is its Chief Executive Officer. The Company has determined that it operates in one operating segment and one reportable segment, as the CODM reviews financial information presented on a consolidated basis for purposes of making operating decisions, allocating resources, and evaluating financial performance. Research and Development Cost Costs related to research and development are expensed as incurred. Stock-Based Compensation The Company measures and recognizes compensation expense for all stock-based awards made to employees, directors, and non-employees, The fair value of options granted is estimated on the grant date using the Black-Scholes option valuation model. This valuation model for stock-based compensation expense requires the Company to make assumptions and judgments about the variables used in the calculation, including the expected term (weighted-average period of time that the options granted are expected to be outstanding), the volatility of the Company’s common stock, and an assumed risk-free interest rate. The Company accounts for forfeitures when they occur. The Company uses the simplified calculation of the expected life, which takes into consideration the grant’s contractual life and vesting period and assumes that all options will be exercised between the vesting date and the contractual term of the option. No awards have been issued with a market condition or other non-standard Given the lack of public market for the Company’s stock prior to the Business Combination and minimal history as a public company subsequent to the Business Combination, the estimate for volatility is based on an average of the historical volatilities of the common stock of several entities with characteristics similar to those of the Company. Since these comparable companies operate in the same industry segment, the Company expects that it would share similar characteristics, such as risks profiles, volatility, capital intensity, clientele, and market growth patterns and drivers. The risk-free rate is based on the U.S. Treasury yield curve in effect at the time of grant for periods corresponding with the expected life of the option. Income Taxes The Company accounts for income taxes under an asset and liability approach. Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes and operating loss carryforwards, measured by applying currently enacted tax laws. Valuation allowances are provided when necessary to reduce net deferred tax assets to an amount that is more likely than not to be realized. The Company recognizes tax liabilities based upon its estimate of whether, and the extent to which, additional taxes will be due when such estimates are more likely than not to be sustained. An uncertain income tax position will not be recognized if it has less than a 50% likelihood of being sustained. Comprehensive Income or Loss The Company’s comprehensive income or loss consists of net income or loss and other comprehensive loss. Unrealized gains or losses on available-for-sale Net Loss per Share of Common Stock Basic net loss per share is computed by dividing the net loss by the weighted-average number of shares of common stock outstanding during the period. Diluted earnings per share adjusts basic earnings per share for the potentially dilutive impact of stock options and warrants. As the Company has reported losses for all periods presented, all potentially dilutive securities including stock options and warrants, are antidilutive and accordingly, basic net loss per share equals diluted net loss per share.

Recent Accounting Pronouncement

Recent Accounting Pronouncements	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
New Accounting Pronouncements And Changes In Accounting Principles [Abstract]
Recent Accounting Pronouncements	Note 3. Recent Accounting Pronouncements In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes ASU 2019-12 removes In August 2020, the FASB issued ASU 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity	3. Recent Accounting Pronouncements In June 2016, the FASB issued ASU 2016-13, Financial Instruments- Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments ASU 2016-13 also of available-for-sale debt In November 2018, the FASB issued ASU 2018-18, Collaborative Arrangement (Topic 808): clarifying the Interaction between Topic 808 and Topic 606 In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes ASU 2019-12 removes In August 2020, the FASB issued ASU 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity

Business Combination

Business Combination	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Business Combinations [Abstract]
Business Combination	Note 4. Business Combination As described in Note 1, on November 25, 2020, the Company consummated the Business Combination Agreement dated September 2, 2020, with Legacy QuantumScape surviving the merger as a wholly owned subsidiary of the Company. At the effective time of the Merger (the “Effective Time”), and subject to the terms and conditions of the Business Combination Agreement, each share of Legacy QuantumScape Class A Common Stock, par value $0.0001 per share, and each share of the Legacy QuantumScape Preferred Stock that was convertible into a share of Legacy QuantumScape Class A Common Stock, was canceled and converted into the right to receive the number of shares of the Company’s Class A Common Stock, $0.0001 par value per share equal to 4.02175014920 (the “Exchange Ratio”), and each share of Legacy QuantumScape Class B Common Stock, par value $0.0001 per share, and each share of the Legacy QuantumScape Preferred Stock that was convertible into a share of Legacy QuantumScape Class B Common Stock was canceled and converted into the right to receive the number of shares of the Company’s Class B Common Stock, $0.0001 par value per share equal to the Exchange Ratio. Upon the closing of the Business Combination (the “Closing”), the Company’s certificate of incorporation was amended and restated to, among other things, increase the total number of authorized shares of all classes of capital stock to 1,350,000,000 shares, $0.0001 par value per share, of which, 1,000,000,000 shares are designated as Class A Common Stock, 250,000,000 shares are designated as Class B Common Stock, and 100,000,000 shares are designated as Preferred Stock. The holder of each share of Class A Common Stock is entitled to one vote, and the holder of each share of Class B Common Stock is entitled to ten votes. In connection with the Business Combination, a number of subscribers (each, a “Subscriber”) purchased from the Company an aggregate of 50,000,000 shares of Class A Common Stock (the “PIPE”), for a purchase price of $10.00 per share and an aggregate purchase price of $500.0 million (the “PIPE Shares”), pursuant to separate subscription agreements (each, a “Subscription Agreement”) entered into effective as of September 2, 2020. The Business Combination was accounted for as a reverse recapitalization in accordance with U.S. GAAP. Under this method of accounting, Kensington was treated as the “acquired” company and Legacy QuantumScape is treated as the acquirer for financial reporting purposes. Accordingly, for accounting purposes, the Business Combination was treated as the equivalent of Legacy QuantumScape issuing stock for the net assets of Kensington, accompanied by a recapitalization. The net assets of Kensington were stated at historical cost, with no goodwill or other intangible assets recorded.	5. Business Combination As discussed in Note 1, on November 25, 2020, the Company consummated the Business Combination Agreement dated September 2, 2020, with Legacy QuantumScape surviving the merger as a wholly owned subsidiary of the Company. At the effective time of the Merger (the “Effective Time”), and subject to the terms and conditions of the Business Combination Agreement, each share of Legacy QuantumScape Class A common stock, par value $0.0001 per share, and each share of the Legacy QuantumScape Preferred Stock that was convertible into a share of Legacy QuantumScape Class A common stock, was canceled and converted into the right to receive the number of shares of the Company’s Class A Common Stock, $0.0001 par value per share (the “Class A Common Stock”) equal to 4.02175014920 (the “Exchange Ratio”), and each share of Legacy QuantumScape Class B common stock, par value $0.0001 per share, and each share of the Legacy QuantumScape Preferred Stock that was convertible into a share of Legacy QuantumScape Class B common stock was canceled and converted into the right to receive the number of shares of the Company’s Class B Common Stock, $0.0001 par value per share (the “Class B Common Stock,” and, together with the Class A Common Stock, the “Common Stock”) equal to the Exchange Ratio. Upon the closing of the Business Combination, the Company’s certificate of incorporation was amended and restated to, among other things, increase the total number of authorized shares of all classes of capital stock to 1,350,000,000 shares, $0.0001 par value per share, of which, 1,000,000,000 shares are designated as Class A Common Stock, 250,000,000 shares are designated as Class B Common Stock, and 100,000,000 shares are designated as Preferred Stock. The holder of each share of Class A common stock is entitled to one vote, and the holder of each share of Class B common stock is entitled to ten votes. In connection with the Business Combination, a number of subscribers (each, a “Subscriber”) purchased from the Company an aggregate of 50,000,000 shares of Class A Common Stock (the “PIPE”), for a purchase price of $10.00 per share and an aggregate purchase price of $500.0 million (the “PIPE Shares”), pursuant to separate subscription agreements (each, a “Subscription Agreement”) entered into effective as of September 2, 2020. The Business Combination is accounted for as a reverse recapitalization in accordance with U.S. GAAP. Under this method of accounting, Kensington was treated as the “acquired” company and Legacy QuantumScape is treated as the acquirer for financial reporting purposes. Accordingly, for accounting purposes, the Business Combination was treated as the equivalent of Legacy QuantumScape issuing stock for the net assets of Kensington, accompanied by a recapitalization. The net assets of Kensington were stated at historical cost, with no goodwill or other intangible assets recorded. The following table reconciles the elements of the Business Combination to the Consolidated Statement of Cash Flows and the Consolidated Statement of Redeemable Non-Controlling Recapitalization Cash- Kensington trust and cash, net of redemptions $ 230,128 Cash- PIPE Financing 500,000 Non-cash 592 Less: Fair value of assumed common stock warrants (Restated) 109,081 Less: transaction costs and advisory fees for QuantumScape allocated to equity (Restated) 41,664 Less: transaction costs and advisory fees for Kensington (Restated) 11,372 Net Business Combination (Restated) $ 568,603 Less: non-cash 592 Less: transaction costs and advisory fees for QuantumScape allocated to warrants (Restated) 1,245 Add: Non-cash 109,081 Add: accrued transaction costs and advisor fees 1,016 Net cash contributions from Business Combination $ 676,863 The number of shares of common stock issued immediately following the consummation of the Business Combination: Number of Common stock, outstanding prior to Business Combination 23,000,000 Less: redemption of Kensington shares 15,255 Common stock of Kensington 22,984,745 Kensington Founder Shares 5,750,000 Shares issued in PIPE Financing 50,000,000 Business Combination and PIPE Financing shares—Class A common stock 78,734,745 Legacy QuantumScape shares—Class A common stock (1) 110,734,478 Legacy QuantumScape shares—Class B common stock (1) 158,301,450 Total shares of common stock immediately after Business Combination 347,770,673 (1) The number of Legacy QuantumScape Class A common stock was determined from the 27,533,913 shares of Legacy QuantumScape Class A common stock outstanding immediately prior to the closing of the Business Combination converted at the Exchange Ratio. All fractional shares were rounded down. (2) The number of Legacy QuantumScape Class B common stock was determined from the 39,361,342 shares of Legacy QuantumScape Class B common stock outstanding immediately prior to the closing of the Business Combination converted at the Exchange Ratio. All fractional shares were rounded down.

Fair Value Measurement

Fair Value Measurement	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Fair Value Measurement	Note 5. Fair Value Measurement The Company’s financial assets and liabilities subject to fair value measurements on a recurring basis and the level of inputs used for such measurements were as follows (amounts in thousands): Fair Value Measured as of March 31, 2021 Level 1 Level 2 Level 3 Total Assets included in: Money market fund (1) $ 755,825 $ — $ — $ 755,825 Marketable securities (2) — 771,101 — 771,101 Total fair value $ 755,825 $ 771,101 $ — $ 1,526,926 Liabilities included in: Assumed common stock warrants (Public) $ 66,860 $ — $ — $ 66,860 Assumed common stock warrants (Private Placement) — 221,179 — 221,179 Total fair value $ 66,860 $ 221,179 $ — $ 288,039 Fair Value Measured as of Level 1 Level 2 Level 3 Total Assets included in: Money market fund (1) $ 12,235 $ — $ — $ 12,235 Marketable securities (2) — 977,326 — 977,326 Total fair value $ 12,235 $ 977,326 $ — $ 989,561 Liabilities included in: Assumed common stock warrants (Public) $ 436,999 $ — $ — $ 436,999 Assumed common stock warrants (Private Placement) — 252,700 — 252,700 Total fair value $ 436,999 $ 252,700 $ — $ 689,699 (1) Money market funds are included in cash and cash equivalents on the Condensed Consolidated Balance Sheet. (2) As of December 31, 2020, marketable securities with original maturities of three months or less of $105.2 million, are included in cash and cash equivalents on the Condensed Consolidated Balance Sheet. As of March 31, 2021, there were no marketable securities with original maturities of three months or less included in cash and cash equivalents on the Condensed Consolidated Balance Sheet. The Company performs routine procedures such as comparing prices obtained from independent sources to ensure that appropriate fair values are recorded. Because the transfer of Private Placement Warrants to anyone outside of certain permitted transferees of Kensington Capital Sponsor LLC (the “Sponsor”). would result in the Private Placement Warrants having substantially the same terms as the Public Warrants, the Company determined that the fair value of each Private Placement Warrant is consistent with that of a Public Warrant. Accordingly, the Private Placement Warrants are classified as Level 2 financial instruments. As of March 31, 2021 and December 31, 2020, the carrying values of cash and cash equivalents, accounts payable and accrued liabilities approximate their respective fair values due to their short-term nature. Marketable Securities The following table summarizes, by major security type, the Company’s assets that are measured at fair value on a recurring basis and are categorized using the fair value hierarchy. Amortized cost net of unrealized gain (loss) is equal to fair value as of March 31, 2021 and December 31, 2020. The fair value as of March 31, 2021 and December 31, 2020, are as follows (amounts in thousands): March 31, 2021 Amortized Cost Unrealized Gain Unrealized Loss Fair Value Level 1 securities Money market fund $ 755,825 $ — $ — $ 755,825 Level 2 securities US government securities 770,958 143 — 771,101 Total $ 1,526,783 $ 143 $ — $ 1,526,926 December 31, 2020 Amortized Cost Unrealized Gain Unrealized Loss Fair Value Level 1 securities Money market fund $ 12,235 $ — $ — $ 12,235 Level 2 securities US government securities 977,357 24 (55 ) 977,326 Total $ 989,592 $ 24 $ (55 ) $ 989,561 Any realized gains and losses and interest income are included in interest income. The Company regularly reviews its available-for-sale marketable The estimated amortized cost and fair value of available-for-sale March 31, 2021 December 31, 2020 Amortized Fair Value Amortized Fair Value Due within one year $ 1,526,783 $ 1,526,926 $ 895,867 $ 895,830 Due after one year and through five years — — 93,725 93,731 Total $ 1,526,783 $ 1,526,926 $ 989,592 $ 989,561 Preferred Stock Warrants In 2011 through 2013, in connection with an equipment and loan security agreement with TriplePoint Capital, the Company issued warrants to purchase 124,586 shares of Legacy QuantumScape Series A convertible preferred stock at $2.20131 per share (“the TPC1 warrants”). The TPC1 warrants were set to expire at the later of 7 years from effective date or five years after an initial public offering or acquisition. In January 2015, the Company entered into another equipment loan and security agreement with TriplePoint Capital. In connection with the borrowing of funds per the agreement, the Company issued warrants to purchase 129,718 shares of Legacy QuantumScape Series C convertible preferred stock at $10.40717 per share (“TPC2 warrants”). The TPC2 warrants were set to expire at the later of 2022 or five years after an initial public offering or acquisition. In connection with the Business Combination, each outstanding and unexercised TCP1 and TPC2 warrant was automatically converted into a warrant to purchase a number of shares of the applicable class of common stock in accordance with the terms of the Business Combination Agreement. During the year ended December 31, 2020, all outstanding TPC1 and TPC2 warrants were net exercised in exchange for 998,460 shares of Class A Common Stock. There was no change in fair value of the TCP1 or TCP2 warrants during the three months ended March 31, 2020.	6. Fair Value Measurement The Company’s financial assets and liabilities subject to fair value measurements on a recurring basis and the level of inputs used for such measurements were as follows (amounts in thousands): Fair Value Measured as of Level 1 Level 2 Level 3 Total Assets included in: Money market fund (1) $ 12,235 $ — $ — $ 12,235 Marketable securities (2) — 977,326 — 977,326 Total fair value $ 12,235 $ 977,326 $ — $ 989,561 Liabilities included in: Assumed common stock warrants (Public) (Restated) $ 436,999 $ — $ — $ 436,999 Assumed common stock warrants (Private Placement) (Restated) — 252,700 — 252,700 Total fair value (Restated) $ 436,999 $ 252,700 $ — $ 689,699 Fair Value Measured as of Level 1 Level 2 Level 3 Total Assets included in: Money market fund (1) $ 5,163 $ — $ — $ 5,163 Marketable securities (2) — 120,599 — 120,599 Total fair value $ 5,163 $ 120,599 $ — $ 125,762 Liabilities included in: Convertible preferred stock warrant liabilities $ — $ — $ 1,860 $ 1,860 Total fair value $ — $ — $ 1,860 $ 1,860 (1) Money market funds are included in Cash and cash equivalents on the Consolidated Balance Sheet. (2) Marketable securities with original maturities of three months or less, in the amount of $105.2 million and $18.7 million, are included in Cash and cash equivalents on the Consolidated Balance Sheet as of December 31, 2020 and December 31, 2019, respectively. The Company performs routine procedures such as comparing prices obtained from independent source to ensure that appropriate fair values are recorded. Because the transfer of Private Placement Warrants to anyone outside of a small group of individuals constituting the sponsors of Kensington would result in the Private Placement Warrants having substantially the same terms as the Public Warrants, the Company determined that the fair value of each Private Placement Warrant is consistent with that of a Public Warrant. Accordingly, the Private Placement Warrants are classified as Level 2 financial instruments. As of December 31, 2019 and 2020, the carrying values of cash and cash equivalents, accounts payable and accrued liabilities approximate their respective fair values due to their short-term nature. Marketable Securities The following table summarizes, by major security type, the Company’s assets that are measured at fair value on a recurring basis and are categorized using the fair value hierarchy. Amortized cost net of unrealized gain (loss) is equal to fair value as of December 31, 2020. The fair value as of December 31, 2020 and 2019, are as follows (amounts in thousands): December 31, 2020 Amortized Cost Unrealized Unrealized Fair Value Level 1 securities Money market fund $ 12,235 $ — $ — $ 12,235 Level 2 securities US government securities 977,357 24 (55 ) 977,326 Total $ 989,592 $ 24 $ (55 ) $ 989,561 December 31, 2019 Amortized Cost Unrealized Unrealized Fair Value Level 1 securities Money market fund $ 5,163 $ — $ — $ 5,163 Level 2 securities Repurchase agreement 13,500 — — 13,500 US government securities 107,009 90 — 107,099 Total Level 2 securities 120,509 90 — 120,599 Total $ 125,672 $ 90 $ — $ 125,762 Any realized gains and losses and interest income are included in interest income. We regularly review our available-for-sale marketable available-for-sale The estimated amortized cost and fair value of available-for-sale December 31, 2020 Amortized Cost Fair Value Due within one year $ 895,867 $ 895,830 Due after one year and through five years 93,725 93,731 Total $ 989,592 $ 989,561 Preferred Stock Warrants In 2011 through 2013, in connection with an equipment and loan security agreement with TriplePoint Capital, the Company issued warrants to purchase 124,586 shares of Legacy QuantumScape Series A convertible preferred stock at $2.20131 per share (“the TPC1 warrants”). The TPC1 warrants were set to expire at the later of 7 years from effective date or five years after an initial public offering or acquisition. In January 2015, the Company entered into another equipment loan and security agreement with TriplePoint Capital. In connection with the borrowing of funds per the agreement, the Company issued warrants to purchase 129,718 shares of Legacy QuantumScape Series C convertible preferred stock at $10.40717 per share (“TPC2 warrants”). The TPC2 warrants were set to expire at the later of 2022 or five years after an initial public offering or acquisition. In connection with the Business Combination, each outstanding and unexercised warrant (“Legacy QuantumScape Warrant”) to purchase shares of Legacy QuantumScape capital stock was automatically converted into a warrant to purchase a number of shares of the applicable class of Common Stock (such warrant, the “Exchanged Warrant”) equal to the product (rounded down to the nearest whole number) of (i) the number of shares of Legacy QuantumScape common stock subject to such Legacy QuantumScape Warrant immediately prior to the Effective Time multiplied by (ii) the Exchange Ratio, at an exercise price per share (rounded up to the nearest whole cent) equal to (A) the exercise price per share of such Legacy QuantumScape Warrant immediately prior to the Effective Time divided by (B) the Exchange Ratio. Accordingly, upon the closing of the Business Combination, the TPC1 warrants became warrants to purchase 501,047 shares of the Company’s Class A Common Stock at $0.5473 per share and the TPC2 warrants became warrants to purchase 521,693 shares of the Company’s Class A Common Stock at $2.5877 per share with an estimated fair value of $22.6 million. Upon the closing the Business Combination and conversion to warrants for the purchase if Class A Common Stock, the fair value of the TPC1 and TPC2 warrants were determined using the OPM with the following assumptions: At Conversion TPC1 Warrants TPC2 Warrants Option term (in years) 5 5 Volatility 70.0 % 70.0 % Risk-free interest rate 0.39 % 0.39 % Expected dividends — — Discount for lack of marketability — — In December 2020, all outstanding TPC1 and TPC2 warrants were net exercised in exchange for 998,460 shares of Class A Common Stock. As of December 31, 2019, the fair value of the TPC1 and TPC2 warrants were re-measured As of December 31, 2019 TPC1 Warrants TPC2 Warrants Option term (in years) 5 5 Volatility 58.5 % 45.0 % Risk-free interest rate 1.69 % 1.69 % Expected dividends — — Discount for lack of marketability 35.0 % 35.0 % The 5-year The following table presents the reconciliation of the TPC warrants measured and recorded at fair value on a recurring basis using the significant unobservable inputs described above (amounts in thousands): TPC1 TPC2 Fair Value Balance at December 31, 2018 $ 984 $ 782 $ 1,766 Re-measurement 52 42 94 Balance at December 31, 2019 1,036 824 1,860 Re-measurement 10,475 10,290 20,765 Reclassification to additional paid-in (11,511 ) (11,114 ) (22,625 ) Balance at December 31, 2020 $ — $ — $ — Convertible Preferred Stock Tranche Liabilities In May 2020 and September 2020, Legacy QuantumScape executed a stock purchase agreement and related agreements and amendments thereto, with VGA for an investment of $200 million in Legacy QuantumScape’s Series F convertible preferred stock. The terms of the Series F Preferred Stock Purchase Agreement with VGA obligated Legacy QuantumScape to issue and sell, and VGA to purchase, up to a total of 7,569,508 shares of Series F convertible preferred stock (the “tranche shares”) at $26.4218 per share, to be funded in two tranches: (1) 3,784,754 shares of Legacy QuantumScape Series F Preferred Stock issued for $100 million on December 1, 2020 (the time-based portion of the agreement, “tranche shares 1”), and (2) 3,784,754 shares of Legacy QuantumScape Series F Preferred Stock will be issued for $100 million subject to certain conditions including the achievement of a specified technical milestone by March 31, 2021, as set forth in such agreements (“tranche shares 2”). The Company concluded that the firm commitment to issue the tranche shares met the definition of a freestanding financial instrument. As the underlying convertible preferred shares of the outstanding tranche liabilities were redeemable outside the control of the Company, the fair value of the tranche liabilities was reported on the Company’s balance sheets as a long-term liability, and the fair value change was recorded in other expense in the Consolidated Statements of Operations and Comprehensive Loss, as noted in the table below. The Series F Preferred Stock Purchase Agreement with VGA, as amended, contains provisions pursuant to which, if the relevant closing of such Series F Preferred Stock Purchase Agreement (in whole or in part) occur only after effectiveness of the Merger, VGA agreed to purchase, and the Company agreed to issue, instead of the relevant number of shares of Legacy QuantumScape Series F Preferred Stock to be purchased at such closing, such number of shares of Class A Common Stock as would have been issued in the Merger in exchange for such shares of Legacy QuantumScape Series F Preferred Stock if they had been outstanding prior to the Merger. As a result of these provisions to issue shares of Class A Common Stock, and upon consummation of the Business Combination, the Company determine its obligation to issue Class A Common Stock pursuant to the Series F Preferred Stock Purchase Agreement was equity classified and the fair value of the tranche liabilities was reclassified to additional paid-in In August 2020, Legacy QuantumScape entered into Series F Preferred Stock Purchase Agreements and related agreements thereto with several new and existing investors, pursuant to which it agreed to sell, and the investors agreed to purchase, an aggregate of 7,115,335 shares of Legacy QuantumScape Series F Preferred Stock at $26.4218 per share for an aggregate purchase price of $188 million (tranche shares 3 and 4), of which: (1) $94.0 million was to be funded at the earlier of December 1, 2020 or a SPAC business combination (“tranche shares 3”), and (2) the remaining $94.0 million tranche (“tranche shares 4”) was to be funded at the earlier of a SPAC business combination closing or March 2021. Similar to the tranche shares to VGA, the Company concluded that the firm commitment to issue the incremental tranche shares 3 and 4 met the definition of a freestanding financial instrument. Pursuant to the terms of these Series F Preferred Stock Purchase Agreements, funding of the tranche shares 3 and 4 occurred concurrent with the closing of the Business Combination. Upon funding and issuance of the 7,115,335 shares of Legacy QuantumScape Series F Preferred Stock, the convertible preferred stock tranche liability associated with tranche shares 3 and 4 was settled and the fair value of the tranche liability was recorded as redeemable convertible preferred stock. The Company remeasured all tranche share liabilities as of closing date of the Business Combination based on the closing market price of Kensington immediately prior to the Business Combination. The fair value of the Legacy QuantumScape’s Series F convertible preferred stock tranches was calculated based on the traded stock price of Kensington at November 25, 2020 of $23.50, adjusted for the Exchange Ratio, less the Series F exercise price of $26.42. The following table presents the reconciliation of the Series F convertible preferred tranche liabilities measured and recorded at fair value on a recurring basis using the significant unobservable inputs described above (amounts in thousands): Fair Value Balance at December 31, 2019 $ — Issuance and re-measurement 999,865 Issuance of Legacy QuantumScape Series F Preferred Stock—tranche shares 3 and 4 (484,471 ) Reclassification to additional paid-in (515,394 ) Balance at December 31, 2020 $ —

Property and Equipment

Property and Equipment	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Property Plant And Equipment [Abstract]
Property and Equipment	Note 6. Property and Equipment Property and equipment at March 31, 2021 and December 31, 2020, consisted of the following (amounts in thousands): March 31 December 31 Computers and hardware $ 836 $ 624 Furniture and fixtures 12,006 10,099 Lab equipment 43,342 37,051 Leasehold improvements 12,935 12,154 Construction-in-progress 24,596 16,078 93,715 76,006 Accumulated depreciation and amortization (34,182 ) (32,310 ) Property and equipment, net $ 59,533 $ 43,696 Depreciation and amortization expense related to property and equipment was $2.2 million and $1.4 million for the three months ended March 31, 2021 and 2020, respectively.	7. Property and Equipment Property and equipment at December 31, 2020 and 2019, consisted of the following (amounts in thousands): December 31, 2020 2019 Computers and hardware $ 624 $ 598 Furniture and fixtures 10,099 4,755 Lab equipment 37,051 25,919 Leasehold improvements 12,154 12,005 Construction-in-progress 16,078 8,610 76,006 51,887 Accumulated depreciation and amortization (32,310 ) (26,395 ) Property and equipment, net $ 43,696 $ 25,492 Depreciation and amortization expense related to property and equipment was $7.5 million and $5.6 million for the years ended December 31, 2020 and 2019, respectively.

Leases

Leases	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Leases [Abstract]
Leases	Note 7. Leases The Company currently leases its headquarters, certain other warehouse space and certain equipment under leases classified as operating leases through January 2028, including estimated renewals. Fixed rent generally escalates each year and the Company is responsible for a portion of the landlord’s operating expenses such as property tax, insurance and common area maintenance. Under the Company’s headquarter lease, the Company has one 60-month The Company does not have any leases classified as financing leases as of March 31, 2021 and December 31, 2020. The components of lease related expense are as follows (amounts in thousands): Three Months Ended March 31, Operating leases 2021 2020 Operating lease cost $ 596 $ 536 Variable lease cost 104 104 Operating lease expense $ 700 $ 640 The components of supplemental cash flow information related to leases are as follows (amounts in thousands): Three Months Ended March 31, 2021 2020 Operating cash flows—operating leases $ 569 $ 496 Right-of-use 690 — Three Months Ended March 31, 2021 2020 Weighted-average remaining lease term—operating leases (in years) 6.7 7.8 Weighted-average discount rate—operating leases 6.90 % 7.00 % As of March 31, 2021, future minimum payments during the next five years and thereafter are as follows (amounts in thousands): Fiscal Year Operating Leases 2021 (remaining nine months) $ 1,719 2022 2,355 2023 2,547 2024 2,344 2025 2,318 Thereafter 4,828 Total 16,111 Less present value discount (3,302 ) Operating lease liabilities $ 12,809 The Company’s lease agreements do not provide an implicit rate, so the Company used an estimated incremental borrowing rate, which was derived from third-party information available at the time the Company adopted ASC 842, Leases, .	8. Leases The Company currently leases its headquarters under a single lease classified as an operating lease expiring in January 2023. Fixed rent escalates each year and the Company is responsible for a portion of the landlord’s operating expenses such as property tax, insurance and common area maintenance. Under the lease, the Company has one 60-month The Company does not have any leases classified as financing leases during the years ended December 31, 2020 and 2019. The components of lease related expense are as follows (amounts in thousands): Year Ended Operating leases 2020 2019 Operating lease cost $ 2,143 $ 2,143 Variable lease cost 409 425 Operating lease expense $ 2,552 $ 2,568 The components of supplemental cash flow information related to leases are as follows (amounts in thousands): Year Ended 2020 2019 Operating cash flows—operating leases $ 1,994 $ 1,936 Right-of-use $ — $ 14,100 Year Ended 2020 2019 Weighted-average remaining lease term—operating leases (in years) 7.1 8.1 Weighted-average discount rate—operating leases 7.00 % 7.00 % As of December 31, 2020, future minimum payments during the next five years and thereafter are as follows (amounts in thousands): Operating Year Ended December 31, 2021 $ 2,053 Year Ended December 31, 2022 2,115 Year Ended December 31, 2023 2,301 Year Ended December 31, 2024 2,318 Year Ended December 31, 2025 2,318 Thereafter 4,828 Total 15,933 Less present value discount (3,469 ) Operating lease liabilities $ 12,464 The Company’s lease agreement does not provide an implicit rate, so the Company used an estimated incremental borrowing rate, which was derived from third-party information available at the time the Company adopted ASC 842, Leases, . Sublease In May 2017, the Company entered into an agreement to sublet approximately 15,000 square feet of the Company’s leased space for the sublease term of 3 years. In March 2018, the sublease agreement was amended to add approximately another 11,000 square feet to the sublease. The Company received $0.9 million for the years ended December 31, 2019 in sublease income and the amounts have been recorded in other income (expense). The sublease was terminated at the end of 2019.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 8. Commitments and Contingencies From time to time, and in the ordinary course of business, the Company may be subject to certain claims, charges and litigation concerning matters arising in connection with the conduct of the Company’s business activities. On December 11, 2020, a putative class action lawsuit was filed by a purported Company warrantholder (Index No. 656963/2020 (Sup. Ct. N.Y. Cnty.)) against the Company. The Company removed the case to federal court, Case No. 1:20-cv-10842 On December 24, 2020, a lawsuit was filed by three purported Company warrantholders (Index No. 657256/2020 (Sup. Ct. N.Y. Cnty.)) against the Company. The complaint alleges, among other things, that the plaintiffs were entitled to exercise warrants within 30 days of the Closing. The complaint also alleges that the proxy statement/prospectus/information statement dated September 21, 2020 and November 12, 2020 is misleading and/or omits material information concerning the exercise of the warrants. The complaint generally seeks monetary damages for alleged breach of contract. Between January 5, 2021 and January 8, 2021, three putative class action lawsuits were filed in the Northern District of California by purported purchasers of Company securities against the Company and its Chief Executive Officer or against the Company, certain members of management and the Board, and VGA. Motions to consolidate these three actions and appoint lead plaintiff and counsel have been submitted. All three complaints allege that the defendants purportedly made false and/or misleading statements and failed to disclose material adverse facts about the Company’s business, operations, and prospects, including information regarding the Company’s battery technology. The complaints allege a purported class that includes persons who purchased or acquired Company securities on certain dates. Two shareholder derivative suits were also filed in February 2021 against 11 officers and directors of the Company and have been consolidated into one action Case No. 3:21-cv-00989-WHO On February 26, 2021, a former consultant submitted a demand for arbitration to JAMS, claiming that the Company breached an obligation to extend the term of his consulting agreement. The arbitration demand seeks either 804,350 shares of the Company’s common stock or damages equal to the value of such shares. For many legal matters, particularly those in early stages, the Company cannot reasonably estimate the possible loss (or range of loss), if any. The Company records an accrual for legal matters at the time or times it determines that a loss is both probable and reasonably estimable. Amounts accrued as of March 31, 2021 and December 31, 2020 were not material. Regarding matters for which no accrual has been made (including the potential for losses in excess of amounts accrued), the Company currently believes, based on its own investigations, that any losses (or ranges of losses) that are reasonably possible and estimable will not, in the aggregate, have a material adverse effect on its financial position, results of operations, or cash flows. However, the ultimate outcome of legal proceedings involves judgments, estimates, and inherent uncertainties and cannot be predicted with certainty. Should the ultimate outcome of any legal matter be unfavorable, the Company’s business, financial condition, results of operations, or cash flows could be materially and adversely affected. The Company may also incur substantial legal fees, which are expensed as incurred, in defending against legal claims.	9. Commitments and Contingencies From time to time, and in the ordinary course of business, the Company may be subject to certain claims, charges and litigation concerning matters arising in connection with the conduct of the Company’s business activities. On December 11, 2020, a putative class action lawsuit was filed by a purported QuantumScape warrantholder (Index No. 656963/2020 (Sup. Ct. N.Y. Cnty.)) against the Company and Continental Stock Transfer & Trust Company. The complaint alleges, among other things, that the plaintiff is entitled to exercise warrants within 30 days of Closing. The complaint also alleges that the proxy statement/prospectus/information statement dated September 21, 2020 and November 12, 2020 is misleading and/or omits material information concerning the exercise of the warrants. The complaint generally seeks, among other things, the ability to exercise the warrants within 30 days of Closing. QuantumScape removed the case to federal court, Case No. 1:20-cv-10842 On December 24, 2020, a lawsuit was filed by three purported QuantumScape warrantholders (Index No. 657256/2020 (Sup. Ct. N.Y. Cnty.)) against the Company. The complaint alleges, among other things, that the plaintiffs are entitled to exercise warrants within 30 days of Closing. The complaint also alleges that the proxy statement/prospectus/information statement dated September 21, 2020 and November 12, 2020 is misleading and/or omits material information concerning the exercise of the warrants. The complaint generally seeks, among other things, the ability to exercise the warrants within 30 days of Closing. Between January 5 and January 8, 2021, three putative class action lawsuits were filed by purported purchasers of QuantumScape securities. (Case No. 3:21-cv-00058-WHO No. 4:21-cv-00070-JST 3:21-cv-00150-VC All three complaints allege that the defendants purportedly made false and/or misleading statements and failed to disclose material adverse facts about QuantumScape’s business, operations, and prospects, including information regarding the Company’s battery technology. The complaints allege a purported class that includes persons who purchased or acquired QuantumScape securities on certain dates. A shareholder derivative suit was also filed against 11 officers and directors of the Company: Case No. 3:21-cv-00989 For many legal matters, particularly those in early stages, the Company cannot reasonably estimate the possible loss (or range of loss), if any. The Company records an accrual for legal matters at the time or times it determines that a loss is both probable and reasonably estimable. Amounts accrued as of December 31, 2020 were not material. Regarding matters for which no accrual has been made (including the potential for losses in excess of amounts accrued), the Company currently believes, based on its own investigations, that any losses (or ranges of losses) that are reasonably possible and estimable will not, in the aggregate, have a material adverse effect on its financial position, results of operations, or cash flows. However, the ultimate outcome of legal proceedings involves judgments, estimates, and inherent uncertainties and cannot be predicted with certainty. Should the ultimate outcome of any legal matter be unfavorable, the Company’s business, financial condition, results of operations, or cash flows could be materially and adversely affected. The Company may also incur substantial legal fees, which are expensed as incurred, in defending against legal claims.

Assumed Common Stock Warrants

Assumed Common Stock Warrants	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Warrants And Rights Note Disclosure [Abstract]
Assumed Common Stock Warrants	Note 9. Assumed Common Stock Warrants As of March 31, 2021 and December 31, 2020, there are 8,660,225 and 18,149,989 warrants outstanding, respectively. As part of Kensington’s initial public offering, 11,499,989 Public Warrants were sold. The Public Warrants entitle the holder thereof to purchase one share of Class A Common Stock at a price of $11.50 per share, subject to adjustments. The Public Warrants may be exercised only for a whole number of shares of Class A Common Stock. No fractional shares will be issued upon exercise of the warrants. The Public Warrants will expire at 5:00 p.m. New York City time on November 25, 2025, or earlier upon redemption or liquidation. The Public Warrants are listed on the NYSE under the symbol “QS.WS”. The Company may redeem the Public Warrants starting July 30, 2021, in whole and not in part, at a price of $0.01 per warrant, so long as the Company provides not less than 30 days’ prior written notice of redemption to each warrantholder, and if, and only if, the reported last sale price of Class A Common Stock equals or exceeds $18.00 per share for any 20 trading days within a 30-trading Simultaneously with Kensington’s initial public offering, Kensington consummated a private placement of 6,575,000 Private Placement Warrants with the Sponsor. Kensington issued an additional 75,000 warrants in connection with the closing of the Business Combination, constituting the Working Capital Warrants. Each Private Placement Warrant and Working Capital Warrant is exercisable for one share of Class A Common Stock at a price of $11.50 per share, subject to adjustment. The Private Placement Warrants and Working Capital Warrants are identical to the Public Warrants, except that: (1) the Private Placement Warrants and Working Capital Warrants and the shares of Class A Common Stock issuable upon exercise of the Private Placement Warrants and Working Capital Warrants are not transferable, assignable or salable until 30 days after the completion of a Business Combination, subject to certain limited exceptions, (2) the Private Placement Warrants and Working Capital Warrants are non-redeemable • in whole and not in part; • at $0.10 per warrant upon a minimum of 30 days’ prior written notice of redemption provided that holders will be able to exercise their warrants on a cashless basis prior to redemption and receive that number of shares of Class A Common Stock to be determined by reference to a table in the warrant agreement; • if, and only if, the last reported sale price of the Company’s Class A Common Stock equals or exceeds $10.00 per share (as adjusted for stock splits, stock dividends, reorganizations, recapitalizations and the like) on the trading day prior to the date on which the Company sends the notice of redemption to the warrantholders; • if, and only if, the Private Placement Warrants and Working Capital Warrants are also concurrently called for redemption at the same price (equal to a number of shares of Class A Common Stock) as the outstanding Public Warrants, as described above; and • if, and only if, there is an effective registration statement covering the shares of Class A Common Stock (or a security other than the Class A Common Stock into which the Class A Common Stock has been converted or exchanged for in the event the Company is not the surviving company in the initial Business Combination) issuable upon exercise of the warrants and a current prospectus relating thereto available throughout the 30-day period (3) the Private Placement Warrants and Working Capital Warrants may be exercised by the holders on a cashless basis, and (4) the holders of the Private Placement Warrants and Working Capital Warrants (including with respect to the shares of common stock issuable upon exercise of the Private Placement Warrants and Working Capital Warrants) are entitled to registration rights. If the Private Placement Warrants and Working Capital Warrants are held by someone other than the Sponsor or its permitted transferees, the Private Placement Warrants and Working Capital Warrants will cease to be Private Placement Warrants or Working Capital Warrants, as applicable, and become Public Warrants and be redeemable by the Company in all redemption scenarios and exercisable by such holders on the same basis as the other Public Warrants. On February 13, 2021 the Warrant Agreement, dated June 25, 2020, by and between the Company and Continental Stock Transfer & Trust Company, was amended to allow for earlier exercise of the Public Warrants. Prior to the amendment, the Public Warrants were exercisable starting on June 30, 2021. Following the amendment, the Public Warrants became exercisable starting on March 5, 2021, at which time holders of Public Warrants could begin exercising their right to purchase one share of the Company’s Class A Common Stock for $11.50 for each Public Warrant. All other terms, including the redemption terms, for the Public Warrants remain unchanged; the Company may not redeem Public Warrants before July 30, 2021. The terms for the Private Placement Warrants and Working Capital Warrants remain unchanged. The Company concluded the Public Warrants and Private Placement Warrants, or Assumed Common Stock Warrants, meet the definition of a derivative under ASC 815 (as described in Note 2) and are recorded as liabilities. Upon consummation of the Business Combination, the fair value of the Assumed Common Stock Warrants was recorded on the Condensed Consolidated Balance Sheet. The fair value of the Assumed Common Stock Warrants was remeasured as of March 31, 2021, resulting in a $30.8 million non-cash During the three months ended March 31, 2021, 9,489,764 Public Warrants were exercised for net proceeds of $109.1 million.	10. Assumed Common Stock Warrants At December 31, 2020, there are 18,149,989 warrants outstanding. As part of Kensington’s initial public offering, 11,499,989 Public Warrants were sold. The Public Warrants entitle the holder thereof to purchase one share of Class A Common Stock at a price of $11.50 per share, subject to adjustments. The Public Warrants may be exercised only for a whole number of shares of Class A Common Stock. No fractional shares will be issued upon exercise of the warrants. The Public Warrants will expire at 5:00 p.m. New York City time on November 25, 2025, or earlier upon redemption or liquidation. The Public Warrants are listed on the NYSE under the symbol “QS.WS.” The Company may redeem the Public Warrants starting July 30, 2021, in whole and not in part, at a price of $0.01 per warrant, so long as the Company provides not less than 30 days’ prior written notice of redemption to each warrantholder, and if, and only if, the reported last sale price of Common Stock equals or exceeds $18.00 per share for any 20 trading days within a 30-trading Simultaneously with Kensington’s initial public offering, Kensington consummated a private placement of 6,575,000 Private Placement Warrants with Kensington’s sponsor. Kensington issued an additional 75,000 Working Capital Warrants in connection with the closing of the Business Combination. Each Private Placement Warrant and Working Capital Warrant is exercisable for one share of Class A Common Stock at a price of $11.50 per share, subject to adjustment. The Private Placement Warrants and Working Capital Warrants are identical to the Public Warrants, except that: (1) the Private Placement Warrants and Working Capital Warrants and the shares of Class A Common Stock issuable upon exercise of the Private Placement Warrants and Working Capital Warrants are not transferable, assignable or salable until 30 days after the completion of a Business Combination, subject to certain limited exceptions, (2) the Private Placement Warrants and Working Capital Warrants are non-redeemable • in whole and not in part; • at $0.10 per warrant upon a minimum of 30 days’ prior written notice of redemption provided that holders will be able to exercise their warrants on a cashless basis prior to redemption and receive that number of shares of Class A Common Stock to be determined by reference to a table in the warrant agreement; • if, and only if, the last reported sale price of the Company’s Class A Common Stock equals or exceeds $10.00 per share (as adjusted for stock splits, stock dividends, reorganizations, recapitalizations and the like) on the trading day prior to the date on which the Company sends the notice of redemption to the warrantholders; • if, and only if, the Private Placement Warrants and Working Capital Warrants are also concurrently called for redemption at the same price (equal to a number of shares of Class A Common Stock) as the outstanding Public Warrants, as described above; and • if, and only if, there is an effective registration statement covering the shares of Class A Common Stock (or a security other than the Class A Common Stock into which the Class A Common Stock has been converted or exchanged for in the event the Company is not the surviving company in the initial Business Combination) issuable upon exercise of the warrants and a current prospectus relating thereto available throughout the 30-day period (3) the Private Placement Warrants and Working Capital Warrants may be exercised by the holders on a cashless basis, and (4) the holders of the Private Placement Warrants and Working Capital Warrants (including with respect to the shares of common stock issuable upon exercise of the Private Placement Warrants and Working Capital Warrants) are entitled to registration rights. If the Private Placement Warrants and Working Capital Warrants are held by someone other than the Sponsor or its permitted transferees, the Private Placement Warrants and Working Capital Warrants will cease to be Private Placement Warrants or Working Capital Warrants, as applicable, and become Public Warrants and be redeemable by the Company in all redemption scenarios and exercisable by such holders on the same basis as the other Public Warrants. On February 13, 2021 the Warrant Agreement, dated June 25, 2020, by and between the Company and Continental Stock Transfer & Trust Company, was amended to allow for earlier exercise of the Public Warrants. Prior to the amendment, the Public Warrants were exercisable starting on June 30, 2021. Following the amendment, the Public Warrants are now exercisable starting on March 5, 2021, at which time holders of Public Warrants may exercise their right to purchase one share of the Company’s Class A Common Stock for $11.50 for each Public Warrant. All other terms, including the redemption terms, for the Public Warrants remain unchanged; the Company may not redeem Public Warrants before July 30, 2021. The terms for the Private Placement Warrants and Working Capital Warrants remain unchanged. The Company concluded the Public Warrants and Private Placement Warrants, or Assumed Common Stock Warrants, meet the definition of a derivative under ASC 815 (as described in Note 2) and are recorded as liabilities. Upon consummation of the Business Combination, the fair value of the Assumed Common Stock Warrants was recorded on the Balance Sheet. The fair value of the Assumed Common Stock Warrants was remeasured as of December 31, 2020, resulting in a $581.9 million non-cash

Stockholders' Equity

Stockholders' Equity	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Stockholders Equity Note [Abstract]
Stockholders' Equity	Note 10. Stockholders’ Equity As of March 31, 2020 and December 31, 2020, 1,350,000,000 shares, $0.0001 par value per share are authorized, of which, 1,000,000,000 shares are designated as Class A Common Stock, 250,000,000 shares are designated as Class B Common Stock, and 100,000,000 shares are designated as Preferred Stock. Common Stock Holders of the common stock are entitled to dividends when, as, and if, declared by the Board, subject to the rights of the holders of all classes of stock outstanding having priority rights to dividends. As of March 31, 2021, the Company had not declared any dividends. The holder of each share of Class A Common Stock is entitled to one vote, and the holder of each share of Class B Common Stock is entitled to ten votes. In March 2021, the Company completed an underwritten public offering of shares of its Class A Common Stock and issued 11,960,000 shares for an aggregate purchase price of $462.9 million, net of issuance costs of $15.5 million (the “March 2021 Public Offering”). Legacy QuantumScape Series F Convertible Preferred Stock In May 2020 and September 2020, Legacy QuantumScape and VGA entered into a Series F Preferred Stock Purchase Agreement and related agreements and amendments thereto, and in August 2020, Legacy QuantumScape and several new and existing investors entered into Series F Preferred Stock Purchase Agreements and related agreements thereto, pursuant to which Legacy QuantumScape agreed to sell, and VGA and other investors agreed to purchase, up to an aggregate 14,684,843 shares of Legacy QuantumScape Series F Preferred Stock at $26.4218 per share for an aggregate purchase price of $388 million (together with the Series F Closing Agreement below, the “Series F Preferred Stock Purchase Agreements”). The Series F Preferred Stock Purchase Agreement with VGA, as amended, contains provisions pursuant to which, if the relevant closing of such Series F Preferred Stock Purchase Agreement (in whole or in part) occurred only after effectiveness of the Business Combination, VGA agreed to purchase, and Kensington agreed to issue, instead of the relevant number of shares of Legacy QuantumScape Series F Preferred Stock to be purchased at such closing, such number of shares of Class A Common Stock as would have been issued in the Business Combination in exchange for such shares of Legacy QuantumScape Series F Preferred Stock if they had been outstanding prior to the Business Combination. Pursuant to the terms of the Series F Preferred Stock Purchase Agreements Legacy QuantumScape issued 7,115,335 shares of Series F Preferred Stock for an aggregate purchase price of $188.0 million, net of issuance costs of $11.5 million, concurrent with the closing of the Business Combination, and the Company issued 15,221,334 shares of Class A Common Stock to VGA for $100.0 million on December 1, 2020. On March 30, 2021, the Company, Legacy QuantumScape, and VGA entered into a Series F Closing Agreement for the Company to issue to VGA an additional 15,221,334 shares of Class A Common Stock (the “Second Closing VGA Shares”) for $100.0 million based on the Company’s achievement of the specified technical milestone. This represents the second and final closing pursuant to the Series F Preferred Stock Purchase Agreements. The required technical milestone was completed as of March 31, 2021 and we received the $100 million in financing subsequent to quarter-end The Company concluded that the firm commitment to issue the tranche shares to VGA and the other investors met the definition of a freestanding financial instrument (as described in Note 5). Prior to the Business Combination, as the underlying convertible preferred shares of the outstanding tranche liabilities were redeemable outside the control of the Company, the fair value of the tranche liabilities was reported on the Legacy QuantumScape’s balance sheets as a long-term liability, and the change in fair value was recorded in other expense in the Condensed Consolidated Statements of Operations and Comprehensive Loss during the year ended December 31, 2020. Upon consummation of the Business Combination, the tranche liabilities were reclassified to additional paid-in Equity Incentive Plans Prior to the Business Combination, the Company maintained its 2010 Equity Incentive Plan (the “2010 Plan”), under which the Company granted options and restricted share units to purchase or directly issue shares of common stock to employees, directors, and non-employees. Upon the Closing, awards under the 2010 Plan were converted at the Exchange Ratio and assumed into the 2020 Equity Incentive Award Plan (the “2020 Plan”, and together with the 2010 Plan, the “Plans”). The 2020 Plan permits the granting of awards in the form of incentive stock options, nonqualified stock options, stock appreciation rights, restricted shares, restricted share units and performance awards to employees, directors, and non-employees. As of March 31, 2021, 41,500,000 shares of Class A Common Stock are authorized for issuance pursuant to awards under the 2020 Plan, plus any shares of Class A Common Stock subject to stock options, restricted stock units or other awards that were assumed in the Business Combination and terminate as a result of being unexercised or are forfeited or repurchased by the Company, with the maximum number of shares to be added to the 2020 Plan equal to 69,846,580 shares of Class A Common Stock. Options may be granted at a price per share not less than 100% of the fair market value at the date of grant. If the option is granted to a 10% stockholder, then the purchase or exercise price per share shall not be less than 110% of the fair market value per share of the common stock on the grant date. Options granted generally vest over a period of four years and have ten-year Stock Options Stock option activity under the Plans during the three months ended March 31, 2021 is as follows: Number of Shares Outstanding Weighted Average Exercise Weighted Average Remaining Contractual Term (Years) Intrinsic (in thousands) Balance as of December 31, 2020 55,316,336 $ 1.62 5.77 Cancelled and forfeited (366,724 ) 2.34 — Exercised (2,884,549 ) 0.30 — Balance as of March 31, 2021 52,065,063 $ 1.69 5.77 $ 2,242,170 Vested and exercisable -March 31, 2021 41,102,851 $ 1.26 5.04 $ 1,787,418 There were no options granted during the three months ended March 31, 2021 or March 31, 2020. The aggregate intrinsic value of options exercised during the three months ended March 31, 2021 and 2020 was $130.6 million and $0.03 million, respectively. Additional information regarding options outstanding at March 31, 2021, is as follows: Range of Exercise Price per Share Number of Options Outstanding Weighted Average Exercise Price Weighted Average Remaining Contractual Life (Years) $0.11 - $0.64 7,910,607 $ 0.49 1.73 $1.05 - $1.35 27,952,167 1.25 5.34 $2.38 13,515,675 2.38 8.32 $6.23 2,686,614 6.23 9.43 52,065,063 $ 1.69 5.77 Stock-based compensation expense is based on the grant-date fair value. The Company recognizes compensation expense for all stock-based awards on a straight-line basis over the requisite service period of the awards, which is generally the option vesting term of four years. As of March 31, 2021, the Company had stock-based compensation of $18.8 million related to unvested stock options not yet recognized that are expected to be recognized over an estimated weighted average period of 3.0 years. Restricted Stock Units Restricted stock unit activity under the Plans are as follows: Number of Restricted Stock Units Weighted Average grant date fair value Balance as of December 31, 2020 13,913,076 $ 8.94 Granted 351,584 46.89 Vested (2,014,071 ) 4.83 Forfeited (347,189 ) 6.62 Balance as of March 31, 2021 11,903,400 $ 10.83 The fair value of restricted stock units which vested during the three months ended March 31, 2021 was $110.0 million. Of the restricted stock units that vested during the three months ended March 31, 2021, 569,752 shares were not issued as of March 31, 2021. These shares will be issued upon receipt of HSR clearance. No restricted stock units vested during the three months ended March 31, 2020. There were no restricted stock units granted prior to August 2020. As of March 31, 2021, unrecognized compensation costs related to restricted stock units granted were $122.0 million and are expected to be recognized over a weighted average period of 3.3 years. Total stock-based compensation expense recognized in the accompanying Condensed Consolidated Statements of Operations and Comprehensive Loss for all equity awards is as follows (amounts in thousands): Three Months Ended March 31, 2021 2020 Research and development $ 6,367 $ 1,356 General and administrative 5,309 841 Total stock-based compensation expense $ 11,676 $ 2,197	11. Stockholders’ Equity As of December 31, 2020, 1,350,000,000 shares, $0.0001 par value per share are authorized, of which, 1,000,000,000 shares are designated as Class A Common Stock, 250,000,000 shares are designated as Class B Common Stock, and 100,000,000 shares are designated as Preferred Stock. Common Stock Holders of the common stock are entitled to dividends when, as, and if, declared by the Company’s Board of Directors, subject to the rights of the holders of all classes of stock outstanding having priority rights to dividends. As of December 31, 2020, the Company had not declared any dividends. The holder of each share of Class A Common Stock is entitled to one vote, and the holder of each share of Class B Common Stock is entitled to ten votes. All common stock outstanding as of December 31, 2020 consists of 207,769,091 Class A Common Stock and 156,224,614 Class B Common Stock. Legacy QuantumScape Series F Convertible Preferred Stock As further described in Note 6 (Fair Value), in May 2020 and September 2020, Legacy QuantumScape and VGA entered into a Series F Preferred Stock Purchase Agreement and related agreements and amendments thereto, and in August 2020, Legacy QuantumScape and several new and existing investors entered into Series F Preferred Stock Purchase Agreements and related agreements thereto, pursuant to which Legacy QuantumScape agreed to sell, and VGA and other investors agreed to purchase, up to an aggregate 14,684,843 shares of Legacy QuantumScape Series F Preferred Stock at $26.4218 per share for an aggregate purchase price of $388 million (the “Series F Preferred Stock Purchase Agreements”). As previously mentioned, the Series F Preferred Stock Purchase Agreement with VGA, as amended, contains provisions pursuant to which, if the relevant closing of such Series F Preferred Stock Purchase Agreement (in whole or in part) occur only after effectiveness of the Business Combination, VGA agreed to purchase, and Kensington agreed to issue, instead of the relevant number of shares of Legacy QuantumScape Series F Preferred Stock to be purchased at such closing, such number of shares of Class A Common Stock as would have been issued in the Business Combination in exchange for such shares of Legacy QuantumScape Series F Preferred Stock if they had been outstanding prior to the Business Combination. Pursuant to the terms of the Series F Preferred Stock Purchase Agreements Legacy QuantumScape issued 7,115,335 shares of Series F Preferred Stock for an aggregate purchase price of $188.0 million, net of issuance costs of $11.5 million, concurrent with the closing of the Business Combination, and the Company issued 15,221,334 shares of Class A Common Stock to VGA for $100.0 million on December 1, 2020. As of December 31, 2020, VGA’s commitment to purchase 15,221,334 shares of Class A Common Stock for $100.0 million subject to certain conditions including the achievement of a specified technical milestone by March 31, 2021, is outstanding. The Company concluded that the firm commitment to issue the tranche shares to VGA and the other investors met the definition of a freestanding financial instrument (as described in Note 6). Prior to the Business Combination, as the underlying convertible preferred shares of the outstanding tranche liabilities were redeemable outside the control of the Company, the fair value of the tranche liabilities was reported on the Legacy QuantumScape’s balance sheets as a long-term liability, and the change in fair value was recorded in other expense in the Consolidated Statements of Operations and Comprehensive Loss. Upon consummation of the Business Combination, the tranche liabilities were reclassified to additional paid-in Equity Incentive Plans Prior to the Business Combination, the Company maintained its 2010 Equity Incentive Plan (the 2010 Plan), under which the Company granted options and restricted share units to purchase or directly issue shares of common stock to employees, directors, and non-employees. Upon closing of the Business Combination, awards under the 2010 Plan were converted at the Exchange Ratio and assumed into the 2020 Equity Incentive Award Plan (the 2020 Plan). The 2020 Plan permits the granting of awards in the form of incentive stock options, nonqualified stock options, stock appreciation rights, restricted shares, restricted share units and performance awards to employees, directors, and non-employees. As of December 31, 2020, 41,500,000 shares of Class A Common Stock are authorized for issuance pursuant to awards under the 2020 Plan, plus any shares of Class A Common Stock subject to stock options, restricted stock units or other awards that were assumed in the Business Combination and terminate as a result of being unexercised or are forfeited or repurchased by the Company, with the maximum number of shares to be added to the 2020 Plan equal to 69,846,580 shares of Class A Common Stock. As of December 31, 2020, 59,625,395 shares of Class A Common Stock are available for future issuance under the 2020 Plan. Options may be granted at a price per share not less than 100% of the fair market value at the date of grant. If the option is granted to a 10% stockholder, then the purchase or exercise price per share shall not be less than 110% of the fair market value per share of the common stock on the grant date. Options granted generally vest over a period of four years and have ten-year Stock Options Stock option activity under the Plans are as follows: Number of Weighted Weighted Intrinsic Balance at December 31, 2018 (as previously reported) 11,112,466 $ 4.15 6.44 Conversion of awards due to recapitalization 33,578,834 (3.12 ) Balance at December 31, 2018, effect of reverse acquisition 44,691,300 1.03 6.44 Granted 11,955,658 2.38 Cancelled and forfeited (571,664 ) 1.43 Exercised (618,404 ) 0.64 Balance at December 31, 2019 55,456,890 $ 1.32 6.32 Granted 3,866,992 5.08 Cancelled and forfeited (3,361,530 ) 0.85 Exercised (646,016 ) 0.93 Balance at December 31, 2020 55,316,336 $ 1.62 5.77 $ 4,582,001 Vested and exercisable —December 31, 2020 41,944,514 $ 1.17 4.88 $ 3,493,198 There were 646,016 options exercised during the year ended December 31, 2020 at the aggregate intrinsic value of $3.5 million. Options with a fair value of $9.1 million and $6.8 million vested in 2020 and 2019, respectively. Additional information regarding options outstanding at December 31, 2020, is as follows: Range of Exercise Price per Share Number of Options Weighted Average Weighted Average $0.11 - $0.64 10,380,188 $ 0.40 1.56 $1.05 - $1.35 28,295,781 1.25 5.57 $2.38 13,953,743 2.38 8.56 $6.23 2,686,624 6.23 9.68 55,316,336 $ 1.62 5.77 Stock-based compensation expense is based on the grant-date fair value. The Company recognizes compensation expense for all stock-based awards on a straight-line basis over the requisite service period of the awards, which is generally the option vesting term of four years. As of December 31, 2020, the Company had stock-based compensation of $22.0 million related to unvested stock options not yet recognized that are expected to be recognized over an estimated weighted average period of 3.1 years. The following weighted average assumptions were used as inputs to the Black-Scholes OPM in determining the estimated grant-date fair value of the Company’s stock options to employees: Year Ended 2020 2019 Volatility 70.00 % 70.00 % Risk-free interest rate 0.39 % 1.92 % Expected term (in years) 6.08 6.02 Expected dividend — — Weighted average fair value at grant date $ 2.67 $ 1.50 Restricted Stock Units Restricted stock unit activity under the Plans are as follows: Number of Weighted Balance at December 31, 2019 — $ — Granted 13,913,076 8.94 Balance at December 31, 2020 13,913,076 $ 8.94 Vested—December 31, 2020 — As of December 31, 2020, unrecognized compensation costs related to Restricted Stock Units granted were $116.8 million and are expected to be recognized over a weighted average period of 3.5 years. Total stock-based compensation expense recognized in the accompanying Consolidated Statements of Operations and Comprehensive Loss for all equity awards is as follows (amounts in thousands): Year Ended 2020 2019 Research and development $ 9,889 $ 4,115 General and administrative 7,135 2,696 Total stock-based compensation expense $ 17,024 $ 6,811

Earnings (Loss) Per Share

Earnings (Loss) Per Share	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Earnings Per Share [Abstract]
Earnings (Loss) Per Share	Note 11. Earnings (Loss) Per Share Basic and diluted earnings per share are the same for each class of common stock because they are entitled to the same liquidation and dividend rights. The following table sets forth the computation of basic and diluted loss per Class A Common Stock and Class B Common Stock (amounts in thousands, except share and per share amounts): Three Months Ended March 31, 2021 2020 Numerator: Net loss attributable to common stockholders $ (75,079 ) $ (15,374 ) Denominator: Weighted average Class A and Class B common shares outstanding—Basic and Diluted 368,783,516 239,792,967 Net loss per share attributable to Class A and Class B Common stockholders—Basic and Diluted $ (0.20 ) $ (0.06 ) Basic and diluted earnings per share was the same for each period presented as the inclusion of all potential Class A Common Stock and Class B Common Stock outstanding would have been anti-dilutive. The following table presents the potential common stock outstanding that was excluded from the computation of diluted net loss per share of common stock as of the periods presented because including them would have been antidilutive: Three Months Ended March 31, 2021 2020 Warrants 8,660,225 1,022,740 Options outstanding 52,065,063 55,264,709 Restricted stock units (1) 12,473,152 — VGA contingent purchase commitment (2) 15,221,334 — Total 88,419,774 56,287,449 (1) Restricted stock units include 569,752 shares vested but not issued, subject to HSR clearance as of March 31, 2021. (2) This refers to VGA’s commitment to purchase the Second Closing VGA Shares subject to certain conditions including the achievement of an agreed technical milestone on or before March 31, 2021 and the expiration or early termination of the waiting period under HSR. See Note 9 and Note 13 for more information.	12. Earnings (Loss) Per Share Basic and diluted earnings per share are the same for each class of common stock because they are entitled to the same liquidation and dividend rights. The following table sets forth the computation of basic and diluted loss per Class A Common Stock and Class B Common Stock (amounts in thousands, except share and per share amounts): Year Ended December 31, 2020 2019 (Restated) Numerator: Net loss attributable to common stockholders $ (1,681,777 ) $ (51,283 ) Denominator: Weighted average Class A and Class B common shares outstanding—Basic and Diluted 252,143,509 239,636,062 Net loss per share attributable to Class A and Class B Common stockholders—Basic and Diluted $ (6.67 ) $ (0.21 ) Basic and diluted earnings per share was the same for each period presented as the inclusion of all potential Class A Common Stock and Class B Common Stock outstanding would have been anti-dilutive. The following table presents the potential common stock outstanding that was excluded from the computation of diluted net loss per share of common stock as of the periods presented because including them would have been antidilutive: Year Ended December 31, 2020 2019 Warrants 18,149,989 1,022,740 Options outstanding 55,316,336 55,456,890 Restricted stock units 13,913,076 — VGA contingent purchase commitment (1) 15,221,334 — Total 102,600,735 56,479,630 (1) This refers to VGA’s commitment to purchase 15,221,334 shares of Class A Common Stock for $100.0 million subject to certain conditions including the achievement of a specified technical milestone by March 31, 2021. See Note 11 for more information.

Joint Venture and Redeemable No

Joint Venture and Redeemable Non-Controlling Interest	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Joint Venture And Non Controlling Interest [Abstract]
Joint Venture and Redeemable Non-Controlling Interest	Note 12. Joint Venture and Redeemable Non-Controlling As described in Note 2, on September 11, 2018, the Company entered into a JVA with VWGoA and VGA and formed QSV. The Company determined the entity was a VIE with a related party, and the Company’s operations were more closely associated with QSV. As such, the Company consolidates QSV for financial reporting purposes, and a non-controlling interest The following table sets forth the change in redeemable non-controlling interest Redeemable Non-Controlling Interest Balance as of December 31, 2020 $ 1,704 Net loss attributable to redeemable non-controlling (10 ) Balance as of March 31, 2021 $ 1,694 Redeemable Non-Controlling Interest Balance as of December 31, 2019 $ 1,710 Net loss attributable to redeemable non-controlling (4 ) Balance as of March 31, 2020 $ 1,706 On May 14, 2020, the Company amended the JVA and other related agreements regarding QSV in connection with VGA’s investment of $200.0 million in the Company’s Series F convertible preferred stock as described in Note 9. The Company determined the amendments represented a reconsideration event and determined that QSV is still a variable interest entity. As the significance and nature of the business of QSV continues to be more aligned with the core business of the Company and the Company continues to absorb a majority of the variability associated with QSV’s anticipated economic performance, the Company continues to be the related party most closely associated with QSV. In September 2020, the Company entered into an agreement with VWGoA under which the Company agreed to reserve $134.0 million from the aggregate proceeds of the Series F Preferred Stock financings and the Business Combination to fund its expected equity contributions to QSV, which amounts are included in cash and cash equivalents in the accompanying Condensed Consolidated Balance Sheet as of March 31, 2021.	13. Joint Venture and Redeemable Non-Controlling As described in Note 2, on September 11, 2018, the Company entered into a JVA with VWGoA and VGA and formed the JV entity. The Company determined the entity was a variable interest entity with a related party, and the Company’s operations were more closely associated with the JV entity. As such, the Company consolidates the JV entity for financial reporting purposes, and a non-controlling interest The following table sets forth the change in redeemable non-controlling interest Redeemable Non-Controlling Balance at December 31, 2018 $ 1,690 Net income attributable to redeemable non-controlling 20 Balance at December 31, 2019 $ 1,710 Net loss attributable to redeemable non-controlling (6 ) Balance at December 31, 2020 $ 1,704 On May 14, 2020, the Company amended the JVA and other related agreements regarding the JV entity in connection with VGA’s investment of $200.0 million in the Company’s Series F convertible preferred stock as described in Note 11. The Company determined the amendments represented a reconsideration event and determined that the JV entity is still a variable interest entity. As the significance and nature of the business of the JV entity continues to be more aligned with the core business of the Company and the Company continues to absorb a majority of the variability associated with the JV entity’s anticipated economic performance, the Company continues to be the related party most closely associated with the JV entity. In September 2020, the Company entered into an agreement with VWGoA under which the Company agreed to reserve $134.0 million from the aggregate proceeds of the Series F Preferred Stock Financings and the Business Combination to fund its expected equity contributions to the JV entity, which amounts are included in Marketable securities in the accompanying Consolidated Balance Sheet as of December 31, 2020.

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2021
Subsequent Events [Abstract]
Subsequent Events	Note 13. Subsequent Events Lease Agreement On April 2, 2021, Legacy QuantumScape entered into a lease agreement for premises consisting of approximately 197,000 rentable square feet of space located in San Jose, California. Legacy QuantumScape’s obligations under the lease are guaranteed by the Company. The lease expires on September 30, 2032, unless earlier terminated in accordance with the lease agreement. Legacy QuantumScape will pay monthly base rent over the term of the lease of between approximately $400,000 and $530,000 and the Company will receive approximately ten (10) months of abated monthly base rent during the first two (2) years of the lease term. Second Closing VGA Shares On April 28, 2021, the HSR waiting period for the Second Closing VGA Shares expired. Pursuant to the terms of the Series F Preferred Stock Purchase Agreements, VGA funded the additional $100 million for the Second Tranche VGA Shares.

Restatement of Consolidated Fin

Restatement of Consolidated Financial Statements	12 Months Ended
	Dec. 31, 2020
Accounting Changes And Error Corrections [Abstract]
Restatement of Consolidated Financial Statements	4. Restatement of Consolidated Financial Statements On April 12, 2021, the staff of the Securities and Exchange Commission (the “SEC Staff”) issued a public statement entitled “Staff Statement on Accounting and Reporting Considerations for Warrants issued by Special Purpose Acquisition Companies (“SPACs”)” (the “Staff Statement”). In the Staff Statement, the SEC Staff expressed its view that certain terms and conditions common to SPAC warrants may require the warrants to be classified as liabilities on the SPAC’s financial statements as opposed to equity. On April 28, 2021, the Audit Committee of our Board of Directors, in consultation with management of the Company, concluded that the Company’s consolidated financial statements as of and for the year ended December 31, 2020 should no longer be relied upon based on the facts described below. As such, the Company is restating its consolidated financial statements as of and for the year ended December 31, 2020 included in this Annual Report. The Assumed Common Stock Warrants, assumed by the Company in connection with the Business Combination, were originally issued as part of Kensington’s initial public offering. As of December 31, 2020 and the year then ended, the Assumed Common Stock Warrants were reflected as a component of equity and did not include the subsequent non-cash 815-40. 815-40 non-cash The material terms of the Assumed Common Stock Warrants are more fully described in Note 10—Assumed Common Stock Warrants. In addition, disclosures and amounts were restated in Note 2—Summary of Significant Accounting Policies, Note 5—Business Combinations, Note 6—Fair Value Measurements, Note 12—Earnings (loss) Per Share, and Note 14—Income Taxes as a result of the Assumed Common Stock Warrants. Impact of the Restatement The impact of the restatement on the Consolidated Balance Sheet, Consolidated Statement of Operations and Comprehensive Loss and Consolidated Statement of Cash Flows for the year ended December 31, 2020 is presented below. The restatement had no impact on net cash flows from operating, investing or financing activities. As of December 31, 2020 As Restatement As (In Thousands, Except per Share Amounts) Balance Sheet Total current assets $ 1,009,168 $ — $ 1,009,168 Total assets $ 1,066,769 $ — $ 1,066,769 Liabilities, redeemable non-controlling Total current liabilities $ 12,350 $ — $ 12,350 Assumed common stock warrant liabilities — 689,699 689,699 Total liabilities 23,594 689,699 713,293 Redeemable non-controlling 1,704 — 1,704 Stockholders’ equity Preferred stock—$0.0001 par value — — — Common stock—$0.0001 par value 36 — 36 Additional paid-in-capital 2,437,242 (107,836 ) 2,329,406 Accumulated other comprehensive loss (31 ) — (31 ) Accumulated deficit (1,395,776 ) (581,863 ) (1,977,639 ) Total stockholders’ equity 1,041,471 (689,699 ) 351,772 Total liabilities, redeemable non-controlling $ 1,066,769 $ — $ 1,066,769 For the Year Ended December 31, 2020 As Restatement As (In Thousands, Except Share and per Share Statement of Operations and Comprehensive Loss Total operating expenses $ 81,021 $ — $ 81,021 Loss from operations (81,021 ) — (81,021 ) Other (expense) income: Interest expense (20,765 ) — (20,765 ) Interest income 1,093 — 1,093 Change in fair value of Series F convertible preferred stock tranche liabilities (999,987 ) — (999,987 ) Change in fair value of assumed common stock warrant liabilities — (581,863 ) (581,863 ) Other income 760 — 760 Total other expense (1,018,899 ) (581,863 ) (1,600,762 ) Net loss (1,099,920 ) (581,863 ) (1,681,783 ) Less: Net loss attributable to non-controlling (6 ) — (6 ) Net loss attributable to common stockholders $ (1,099,914 ) $ (581,863 ) $ (1,681,777 ) Net loss $ (1,099,920 ) $ (581,863 ) $ (1,681,783 ) Other comprehensive loss: Unrealized loss on marketable securities (121 ) — (121 ) Total comprehensive loss (1,100,041 ) (581,863 ) (1,681,904 ) Less: Comprehensive loss attributable to non-controlling (6 ) — (6 ) Comprehensive loss attributable to common stockholders $ (1,100,035 ) $ (581,863 ) $ (1,681,898 ) Basic and Diluted net loss per share $ (4.36 ) $ (6.67 ) Basic and Diluted weighted-average common shares outstanding 252,143,509 252,143,509 For the Year Ended December 31, 2020 As Restatement As (In Thousands) Statement of Cash Flows Net loss $ (1,099,920 ) $ (581,863 ) $ (1,681,783 ) Adjustments to reconcile net loss to net cash used in operating activities 1,038,657 581,863 1,620,520 Net cash used in operating activities (61,263 ) — (61,263 ) Net cash used in investing activities (802,648 ) — (802,648 ) Net cash provided by financing activities 953,724 — 953,724 Subsequent Warrant Exercises From January 1, 2021 through May 6, 2021, 9,699,528 Public Warrants were exercised for net proceeds of $111.5 million.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income Taxes	14. Income Taxes The Company has no provision for income taxes for the years ended December 31, 2020 and 2019. The Company has no current tax expense from losses and no deferred expense from the valuation allowance. A reconciliation from U.S. statutory rate of 21% to the effective rate is as follows: Year Ended December 31, 2020 2019 (Restated) Federal Statutory rate 21.0 % 21.0 % State tax expense 0.0 % 7.0 % Permanent tax items (0.2 %) (2.2 %) R&D tax credit 0.2 % 4.5 % Other (0.1 %) 0.0 % Change to valuation allowance (1.1 %) (30.4 %) Change in fair value of assumed common stock warrant liabilities (7.3 %) 0.0 % Change in fair value of Series F tranche liabilities (12.5 %) 0.0 % Effective tax rate 0.0 % 0.0 % Significant components of the Company’s net deferred tax assets as of December 31, 2020 and 2019, are as follows (amounts in thousands): Year Ended 2020 2019 Deferred tax assets: Net operating losses $ 88,392 $ 71,374 Tax credits 16,314 10,219 Accruals and stock-based compensation 3,313 4,671 Lease liability 2,621 3,796 Intangibles 1,413 90 Gross deferred tax assets 112,053 90,150 Valuation allowance (105,781 ) (85,677 ) Total deferred tax assets $ 6,272 $ 4,473 Deferred tax liabilities: Right of use assets $ (2,463 ) (3,627 ) Fixed assets (3,809 ) (846 ) Total deferred tax liabilities (6,272 ) (4,473 ) Total net deferred tax assets $ — $ — Recognition of deferred tax assets is appropriate when realization of such assets is more likely than not. Based upon the weight of available evidence, which includes the Company’s historical operating performance, cumulative net losses, and projected future losses, the Company has provided a full valuation allowance against its deferred tax assets. The Company’s valuation allowance increased by $20.1 million and $14.3 million for the years ended December 31, 2020 and 2019, respectively. A reconciliation of the beginning and ending balances of the valuation allowance is as follows (amounts in thousands): Year Ended December 31, 2020 2019 Beginning of the year $ (85,677 ) $ (71,340 ) Increase (20,104 ) (14,337 ) End of the year $ (105,781 ) $ (85,677 ) At December 31, 2020, the Company had federal and state net operating loss carryforwards of approximately $340.7 million and $231.2 million, respectively. The federal net operating loss carryforwards of $170.3 million generated prior to 2018 will expire at various dates beginning in 2030, if not utilized. We have federal net operating loss carryforwards of $170.4 million, which can be carried forward indefinitely. The state net operating loss carryforwards of $231.2 million will expire at various dates beginning in 2030, if not utilized. Section 382 and Section 383 of the Internal Revenue Code and similar provisions under state law has limitations on federal and state net operating loss carryforwards and research and development credit carryforwards. The Tax Reform Act contains provisions that limit the federal net operating loss carryforwards that may be used in any given year in the event of special occurrences, including significant ownership changes. A Section 382 “ownership change” generally occurs if one or more stockholders or groups of stockholders, who own at least 5% of the Company’s stock, increase their ownership by more than 50 percentage points over their lowest ownership percentage within a rolling three-year period. The Company performed the analysis and determined that it has experienced an ownership change in December 2010 and in August 2012 as a result of the preferred stock financing rounds. The federal and state net operating loss carryforwards and research and development credit carryforwards are not subject to significant limitations under Section 382 and Section 383 of the Internal Revenue Code and similar provisions under state law. On September 9, 2019, the Treasury Department and the IRS issued proposed regulations under Section 382 of the Internal Revenue Code which, if finalized, will severely limit the ability of corporations to avail themselves of NOLs following an ownership change. Specifically, the regulations would eliminate a safe harbor established in Notice 2003-65 As of December 31, 2020, the Company also has Federal and California research and development credits of $13.4 million and $11.3 million, respectively. The federal tax credit carryforwards will expire beginning in 2031, if not utilized. The state tax credit carryforwards do not expire. The Company records unrecognized tax benefits in accordance with ASC 740-10, Income Taxes 740-10 de-recognition, A reconciliation of the beginning and ending balances of unrecognized tax benefits is as follows (amounts in thousands): Year Ended December 31, 2020 2019 Beginning of the year $ 7,076 $ 5,372 Increase—current year positions 1,553 1,704 Increase—prior year positions 193 — Decrease—prior year positions (2,247 ) — End of the year $ 6,575 $ 7,076 Due to the Company’s full valuation allowance, the unrecognized tax benefits would not materially impact the Company’s effective tax rate when recognized. The Company does not anticipate the total amounts of unrecognized tax benefits will significantly increase or decrease in the next 12 months. The Company’s policy is to classify interest and penalties associated with uncertain tax positions, if any, as a component of its income tax provision. For the years ended December 31, 2020 and 2019, the Company had no interest or penalties related to unrecognized tax benefits. The federal and state income tax returns are open under the statute of limitations subject to tax examinations for the tax years ended December 31, 2017 through December 31, 2019 and December 31, 2016 through December 31, 2019, respectively. To the extent the Company has tax attribute carryforwards, the tax year in which the attribute was generated may still be adjusted upon examination by the IRS or state tax authorities to the extent utilized in a future period. The Coronavirus Aid, Relief, and Economic Security Act (“CARES Act”) signed in to law on March 27, 2020, provided that net operating losses (“NOLs”) generated in a taxable year beginning in 2018, 2019, or 2020, may now be carried back five years and forward indefinitely. In addition, the 80% taxable income limitation is temporarily removed, allowing NOLs to fully offset net taxable income. The CARES Act did not materially impact the Company’s tax position. Section 2301 of the CARES Act provides Employee Retention Credit, a fully refundable tax credit for employers equal to 50 percent of qualified wages that Eligible Employers pay their employees. In 2020, the Company claimed $0.9 million of employee retention credit that reduces the payroll tax expense.

Related Party Agreements

Related Party Agreements	12 Months Ended
	Dec. 31, 2020
Related Party Transactions [Abstract]
Related Party Agreements	15. Related Party Agreements Joint Venture Agreement In September 11, 2018, the Company entered into a JVA with VWGoA and VGA as described in Note 2. In connection with this agreement, the parties also have entered into two operating agreements: (i) the Limited Liability Company Agreement of the JV entity to govern the respective rights and obligations as Members of the JV entity and (ii) the Common IP License Agreement for the Company to license certain intellectual property rights pertaining to automotive battery cells as defined in the JVA to VWGoA, VGA and the JV Entity.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The Company’s unaudited condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”) as determined by the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) and pursuant to the regulations of the U.S. Securities and Exchange Commission (“SEC”). Pursuant to the Business Combination Agreement, the merger between Merger Sub and Legacy QuantumScape was accounted for as a reverse recapitalization in accordance with U.S. GAAP (the “Reverse Recapitalization”). Under this method of accounting, Kensington was treated as the “acquired” company and Legacy QuantumScape is treated as the acquirer for financial reporting purposes. Accordingly, for accounting purposes, the Reverse Recapitalization was treated as the equivalent of Legacy QuantumScape issuing stock for the net assets of Kensington, accompanied by a recapitalization. The net assets of Kensington are stated at historical cost, with no goodwill or other intangible assets recorded. Legacy QuantumScape was determined to be the accounting acquirer based on the following predominant factors: • Legacy QuantumScape’s shareholders have the largest portion of voting rights in the Company; • the Company’s Board of Directors (the “Board”) and management are primarily composed of individuals associated with Legacy QuantumScape; and • Legacy QuantumScape was the larger entity based on historical operating activity and Legacy QuantumScape has the larger employee base at the time of the Business Combination. The consolidated assets, liabilities and results of operations prior to the Reverse Recapitalization are those of Legacy QuantumScape. The shares and corresponding capital amounts and losses per share, prior to the Business Combination, have been retroactively restated based on shares reflecting the Exchange Ratio (as defined below) established in the Business Combination.	Basis of Presentation The Company’s consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”) as determined by the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) and pursuant to the regulations of the U.S. Securities and Exchange Commission (“SEC”). Pursuant to the Business Combination Agreement, the merger between Merger Sub and Legacy QuantumScape was accounted for as a reverse recapitalization in accordance with U.S. GAAP (the “Reverse Recapitalization”). Under this method of accounting, Kensington was treated as the “acquired” company and Legacy QuantumScape is treated as the acquirer for financial reporting purposes. Accordingly, for accounting purposes, the Reverse Recapitalization was treated as the equivalent of Legacy QuantumScape issuing stock for the net assets of Kensington, accompanied by a recapitalization. The net assets of Kensington are stated at historical cost, with no goodwill or other intangible assets recorded. Legacy QuantumScape was determined to be the accounting acquirer based on the following predominant factors: • Legacy QuantumScape’s shareholders have the largest portion of voting rights in the Company; • the Board and Management are primarily composed of individuals associated with Legacy QuantumScape; and • Legacy QuantumScape was the larger entity based on historical operating activity and Legacy QuantumScape has the larger employee base at the time of the Business Combination. The consolidated assets, liabilities and results of operations prior to the Reverse Recapitalization are those of Legacy QuantumScape. The shares and corresponding capital amounts and losses per share, prior to the Business Combination, have been retroactively restated based on shares reflecting the exchange ratio established in the Business Combination.
Use of Estimates	Use of Estimates The preparation of the condensed consolidated financial statements in accordance with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of commitments and contingencies at the date of the financial statements as well as reported amounts of expenses during the reporting periods. Estimates made by the Company include, but are not limited to, those related to the valuation of common stock prior to the Business Combination, valuation of convertible preferred stock warrants, and valuation of convertible preferred stock tranche liabilities, among others. The Company bases these estimates on historical experience and on various other assumptions that it believes are reasonable under the circumstances, the results of which form the basis for making judgments about the carrying amounts of assets and liabilities that are not readily apparent from other sources. Actual results could differ materially from those estimates.	Use of Estimates The preparation of financial statements in accordance with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of commitments and contingencies at the date of the financial statements as well as reported amounts of expenses during the reporting periods. Estimates made by the Company include, but are not limited to, those related to the valuation of common stock prior to the Business Combination, valuation of convertible preferred stock warrants, and valuation of convertible preferred stock tranche liabilities, among others. The Company bases these estimates on historical experience and on various other assumptions that it believes are reasonable under the circumstances, the results of which form the basis for making judgments about the carrying amounts of assets and liabilities that are not readily apparent from other sources. Actual results could differ materially from those estimates.
Unaudited Interim Condensed Consolidated Financial Statements	Unaudited Interim Condensed Consolidated Financial Statements The accompanying interim condensed consolidated balance sheet as of March 31, 2021, the interim condensed consolidated statements of redeemable non-controlling These unaudited interim condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and the related notes included in the Company’s audited annual consolidated financial statements for the year ended December 31, 2020 included in the Company’s Annual Report on Form 10-K/A
Principles of Consolidation	Principles of Consolidation The Company’s policy is to consolidate all entities that it controls by ownership of a majority of the outstanding voting stock. In addition, the Company consolidates entities that meet the definition of a variable interest entity (“VIE”) for which the Company is the related party most closely associated with and is the primary beneficiary. The primary beneficiary is the party who has the power to direct the activities of a VIE that most significantly impact the entity’s economic performance and who has an obligation to absorb losses of the entity or a right to receive benefits from the entity that could potentially be significant to the entity. For consolidated entities that are less than wholly owned, the third party’s holding of an equity interest is presented as redeemable non-controlling Non-Controlling non-controlling non-controlling The Company was a single-legal entity prior to becoming a partner with Volkswagen in QSV Operations LLC (“QSV”). As noted in the section titled “ Joint Venture and Redeemable Non-Controlling	Principles of Consolidation The Company’s policy is to consolidate all entities that it controls by ownership of a majority of the outstanding voting stock. In addition, the Company consolidates entities that meet the definition of a variable interest entity (“VIE”) for which the Company is the related party most closely associated with and is the primary beneficiary. The primary beneficiary is the party who has the power to direct the activities of a VIE that most significantly impact the entity’s economic performance and who has an obligation to absorb losses of the entity or a right to receive benefits from the entity that could potentially be significant to the entity. For consolidated entities that are less than wholly owned, the third party’s holding of an equity interest is presented as Redeemable non-controlling Non-Controlling non-controlling non-controlling The Company was a single-legal entity prior to becoming a partner with Volkswagen in QSV Operations LLC (the “JV entity”). As noted in “Joint Venture” discussion, the Company determined the JV entity was a VIE for which it was required to consolidate the operations upon its formation in 2018. The Company continued to consolidate the operations of the JV entity in 2020 as the determination of the variable interest entity has not changed.
Joint Venture and Redeemable Non-Controlling Interest	Joint Venture and Redeemable Non-Controlling On June 18, 2018, QSV was incorporated as a limited liability company. Volkswagen Group of America, Inc. (“VWGoA”), Volkswagen Group of America Investments, LLC (“VGA”) and QuantumScape executed a Joint Venture Agreement (“JVA”), effective September 2018, with the goal of jointly establishing a manufacturing facility in the United States to produce the pilot line of the Company’s product through QSV. In connection with this agreement, the parties also have entered into two operating agreements: (i) the Limited Liability Company Agreement of QSV to govern the respective rights and obligations as Members of QSV and (ii) the Common IP License Agreement for the Company to license certain intellectual property rights pertaining to automotive battery cells as defined in the JVA to VWGoA, VGA and QSV. Volkswagen is a related party stockholder (13.7% and 13.2% voting interest holder of the Company as of March 31, 2021 and December 31, 2020, respectively). Upon the effectiveness of the JVA, each party contributed $1.7 million in cash to capitalize QSV in exchange for 50% equity interests. The joint venture is considered a VIE with a related party and therefore the related party whose business is more closely related to the planned operations of the joint venture is required to consolidate the operations. The Company determined its operations were most closely aligned with the operations of the joint venture and therefore has consolidated the results of QSV’s operations in its Condensed Consolidated Balance Sheets, Condensed Consolidated Statements of Operations and Comprehensive Loss and Condensed Consolidated Statements of Redeemable Non-Controlling The Company classifies non-controlling 480-10-S99-3A, Classification and Measurement of Redeemable Securities 480-10-S99-3A”). non-controlling non-controlling non-controlling non-controlling	Joint Venture and Redeemable Non-Controlling On June 18, 2018, the JV entity was incorporated as a limited liability company. Volkswagen Group of America, Inc. (“VWGoA”), Volkswagen Group of America Investments, LLC (“VGA”) and QuantumScape executed a Joint Venture Agreement (“JVA”), effective September 2018, with the goal of jointly establishing a manufacturing facility in the United States to produce the pilot line of the Company’s product through the JV entity. Volkswagen is a related party stockholder (13.2% and 13.1% voting interest holder of the Company as of December 31, 2020 and December 31, 2019, respectively). Upon the effectiveness of the JVA, each party contributed $1.7 million in cash to capitalize the JV entity in exchange for 50% equity interests. The joint venture is considered a variable interest entity with a related party and therefore the related party whose business is more closely related to the planned operations of the joint venture is required to consolidate the operations. The Company determined its operations were most closely aligned with the operations of the joint venture and therefore has consolidated the results of the JV entity’s operations in its Consolidated Balance Sheets, Consolidated Statements of Operations and Comprehensive Loss and Consolidated Statements of Redeemable Non-Controlling The Company classifies non-controlling 480-10-S99-3A, 480-10-S99-3A”). non-controlling non-controlling non-controlling non-controlling
Concentrations of Credit Risk	Concentrations of Credit Risk Financial instruments that potentially subject the Company to credit risk consist principally of cash and cash equivalents and marketable securities. As of March 31, 2021 and December 31, 2020, approximately $755.8 million and $12.2 million of our total cash and cash equivalents and marketable securities, are held in a U.S. government money market fund, and $771.1 million and $977.3 million are invested in U.S. government and agency securities, respectively. The Company seeks to mitigate its credit risk with respect to cash and cash equivalents and marketable securities by making deposits with large, reputable financial institutions and investing in high credit rated shorter-term instruments.	Concentrations of Credit Risk Financial instruments that potentially subject the Company to credit risk consist principally of cash and cash equivalents, of which $12.2 million is held in a US government Money Market fund and marketable securities, of which $977.3 million is invested in US government and agency securities. The Company seeks to mitigate its credit risk with respect to cash and cash equivalents and marketable securities by making deposits with large, reputable financial institutions and investing in high credit rated shorter-term instruments.
Cash and Cash Equivalents and Restricted Cash	Cash and Cash Equivalents and Restricted Cash Management considers all highly liquid investments with an insignificant interest rate risk and original maturities of three months or less to be cash equivalents. Restricted cash, if the date of availability or disbursement is longer than one year and the balances are maintained under an agreement that legally restricts the use of such funds, is not included within cash and cash equivalents and is reported within other assets. Restricted cash is comprised of $2.2 million, of which $2.0 million is pledged as a form of security for the Company’s lease agreement for its headquarters facility and $0.2 million as collateral for a commercial letter of credit issued to an equipment supplier as of March 31, 2021. As of December 31, 2020, restricted cash was $2.2 million.	Cash and Cash Equivalents and Restricted Cash Management considers all highly liquid investments with an insignificant interest rate risk and original maturities of three months or less to be cash equivalents. Restricted cash, if the date of availability or disbursement is longer than one year and the balances are maintained under an agreement that legally restricts the use of such funds, is not included within cash and cash equivalents and is reported within other assets. Restricted cash is comprised of $2.2 million, of which $2.0 million is pledged as a form of security for the Company’s facility lease agreement and $0.2 million as collateral for a commercial letter of credit issued to an equipment supplier as of December 31, 2020. As of December 31, 2019, restricted cash was $2.8 million.
Marketable Securities	Marketable Securities The Company’s investment policy is consistent with the definition of available-for-sale These debt securities are carried at estimated fair value with unrealized holding gains and losses included in other comprehensive loss in stockholders’ equity until realized. Gains and losses on marketable security transactions are reported on the specific-identification method. Dividend and interest income are recognized when earned.	Marketable Securities The Company’s investment policy is consistent with the definition of available-for-sale These debt securities are carried at estimated fair value with unrealized holding gains and losses included in other comprehensive loss in stockholders’ deficit until realized. Gains and losses on marketable security transactions are reported on the specific-identification method. Dividend and interest income are recognized when earned.
Fair Value Measurement	Fair Value Measurement The Company applies fair value accounting for all financial assets and liabilities measured on a recurring and nonrecurring basis. Fair value is defined as an exit price, representing the amount 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. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or a liability. The accounting guidance established a fair value hierarchy based on three levels of inputs, of which the first two are considered observable and the last unobservable, used to determine the fair value of its financial instruments. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. • Level 1 – Quoted prices in active markets for identical assets or liabilities that the entity has the ability to access. • Level 2 – Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets and liabilities. • Level 3 – Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets and liabilities.	Fair Value Measurement The Company applies fair value accounting for all financial assets and liabilities measured on a recurring and nonrecurring basis. Fair value is defined as an exit price, representing the amount 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. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or a liability. The accounting guidance established a fair value hierarchy based on three levels of inputs, of which the first two are considered observable and the last unobservable, used to determine the fair value of its financial instruments. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. • Level 1 – Quoted prices in active markets for identical assets or liabilities that the entity has the ability to access. • Level 2 – Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets and liabilities. • Level 3 – Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets and liabilities.
Property and Equipment	Property and Equipment Property and equipment are stated at cost, less accumulated depreciation. Depreciation is computed using the straight-line method over the estimated useful life of the related asset. The estimated useful lives of assets are as follows: Computers and hardware 3 years Furniture and fixtures 7 years Lab equipment 5 years Leasehold improvements Shorter of the lease term (including estimated renewals) or the estimated useful lives of the improvements Maintenance and repairs are charged to expense as incurred, and improvements are capitalized. When assets are retired or otherwise disposed of, the cost and accumulated depreciation are removed from the accounts, and any resulting gain or loss is reflected in the accompanying statements of operations and comprehensive loss in the period realized.	Property and Equipment Property and equipment are stated at cost, less accumulated depreciation. Depreciation is computed using the straight-line method over the estimated useful life of the related asset. The estimated useful lives of assets are as follows: Computers and hardware 3 years Furniture and fixtures 7 years Lab equipment 5 years Building and improvements 25 years Leasehold improvements Shorter of the lease term (including estimated renewals) or the estimated useful lives of the improvements Maintenance and repairs are charged to expense as incurred, and improvements are capitalized. When assets are retired or otherwise disposed of, the cost and accumulated depreciation are removed from the accounts, and any resulting gain or loss is reflected in the accompanying statements of operations and comprehensive loss in the period realized.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets The Company evaluates the carrying value of long-lived assets when indicators of impairment exist. The carrying value of a long-lived asset is considered impaired when the estimated separately identifiable, undiscounted cash flows from such an asset are less than the carrying value of the asset. In that event, a loss is recognized based on the amount by which the carrying value exceeds the fair value of the long-lived asset. Fair value is determined primarily using the estimated cash flows discounted at a rate commensurate with the risk involved. There were no material impairment charges in any of the periods presented.	Impairment of Long-Lived Assets The Company evaluates the carrying value of long-lived assets when indicators of impairment exist. The carrying value of a long-lived asset is considered impaired when the estimated separately identifiable, undiscounted cash flows from such an asset are less than the carrying value of the asset. In that event, a loss is recognized based on the amount by which the carrying value exceeds the fair value of the long-lived asset. Fair value is determined primarily using the estimated cash flows discounted at a rate commensurate with the risk involved. There were no material impairment charges in any of the periods presented.
Leases	Leases The Company accounts for its leases under ASC 842, Leases right-of-use right-of-use right-of-use In calculating the right-of-use non-lease	Leases The Company accounts for its leases under ASC 842, Leases. Under this guidance, lessees classify arrangements meeting the definition of a lease as operating or financing leases, and leases are recorded on the Consolidated Balance Sheet as both a right-of-use right-of-use right-of-use In calculating the right-of-use non-lease
Convertible Preferred Stock	Convertible Preferred Stock Prior to the Business Combination, the Company recorded shares of convertible preferred stock at their respective fair values on the dates of issuance, net of issuance costs. The Company applied the guidance in ASC 480-10-S99-3A All convertible preferred stock previously classified as temporary equity was retroactively adjusted, converted into Class A and Class B Common Stock, and reclassified to permanent as a result of the Business Combination. Convertible preferred stock converted into shares of Legacy QuantumScape Class A and Class B Common Stock and were immediately exchanged for Class A and Class B Common Stock of the Company, as described in Note 4. In March 2016 and March 2017, Legacy QuantumScape issued shares of Legacy QuantumScape Series D convertible preferred stock to two new strategic investors and to an existing strategic investor for net proceeds of $59.7 million. Legacy QuantumScape determined that the Legacy QuantumScape Series D convertible preferred stock share purchase agreements with these investors contained strategic terms as all of these investors had strategic interests in the Company’s technology and negotiated specific strategic terms expected to benefit these new investors, over and above the value that would be expected to be realized from the equity investment itself. Thus, the sale of the Legacy QuantumScape Series D convertible preferred stock to these investors reflected a higher price (“strategic premium”) than what a market participant who did not receive these strategic benefits would be willing to pay. Legacy QuantumScape allocated the net proceeds from these investors between the Legacy QuantumScape Series D convertible preferred stock and the strategic premium resulting in a strategic premium of $7.9 million which it recorded as a deferred liability on the balance sheet. The strategic premium is considered akin to payment for research and development efforts. Legacy QuantumScape’s accounting policy is to record research and development effort payments as contra research and development and recorded the benefits (amortization of the strategic premium) over the estimated period of the development agreements with the investors which is re-assessed For the three months ended March 31, 2021 and 2020, the Company recorded amortization of $0.2 million and $0.2 million, respectively.	Convertible Preferred Stock Prior to the Business Combination, the Company recorded shares of convertible preferred stock at their respective fair values on the dates of issuance, net of issuance costs. The Company applied the guidance in ASC 480-10-S99-3A All convertible preferred stock previously classified as temporary equity was retroactively adjusted, converted into Class A and Class B Common Stock, and reclassified to permanent as a result of the Business Combination. Convertible preferred stock converted into shares of Legacy QuantumScape Class A and Class B Common Stock and were immediately exchanged for Class A and Class B Common Stock of the Company, see Note 6. In March 2016 and March 2017, Legacy QuantumScape issued shares of Legacy QuantumScape Series D convertible preferred stock to two new strategic investors and to an existing strategic investor for net proceeds of $59.7 million. Legacy QuantumScape determined that the Legacy QuantumScape Series D convertible preferred stock share purchase agreements with these investors contained strategic terms as all of these investors had strategic interests in the Company’s technology and negotiated specific strategic terms expected to benefit these new investors, over and above the value that would be expected to be realized from the equity investment itself. Thus, the sale of the Legacy QuantumScape Series D convertible preferred stock to these investors reflected a higher price (“strategic premium”) than what a market participant who did not receive these strategic benefits would be willing to pay. Legacy QuantumScape allocated the net proceeds from these investors between the Legacy QuantumScape Series D convertible preferred stock and the strategic premium resulting in a strategic premium of $7.9 million which it recorded as a deferred liability on the balance sheet. The strategic premium is considered akin to payment for research and development efforts. Legacy QuantumScape’s accounting policy is to record research and development effort payments as contra research and development and recorded the benefits (amortization of the strategic premium) over the estimated period of the development agreements with the investors which is re-assessed For the years ended December 31, 2020 and December 31, 2019, the Company recorded amortization of $0.7 million and $0.9 million, respectively.
Free-Standing Convertible Preferred Stock Warrants Liability	Free-Standing Convertible Preferred Stock Warrants Liability Free-standing warrants issued by Legacy QuantumScape for the purchase of shares of its convertible preferred stock were classified as liabilities on the accompanying balance sheets at fair value using an Option-Pricing Model (“OPM”). Prior to the Business Combination, the liability recorded was adjusted for changes in the fair value at each reporting date and recorded as interest expense in the accompanying Condensed Consolidated Statements of Operations and Comprehensive Loss. As a result of the Business Combination, the Legacy QuantumScape warrants each converted into a warrant to purchase shares of the Company’s Class A Common Stock converted at the Exchange Ratio (as described below). The Company determined the warrants to be equity classified and the fair value of the warrants upon consummation of the Business Combination, as adjusted based on the price of the underlying Class A Common Stock, was reclassified to additional paid-in	Free-Standing Convertible Preferred Stock Warrants Liability Free-standing warrants issued by Legacy QuantumScape for the purchase of shares of its convertible preferred stock were classified as liabilities on the accompanying balance sheets at fair value using an Option-Pricing Model (“OPM”). Prior to the Business Combination, the liability recorded was adjusted for changes in the fair value at each reporting date and recorded as interest expense in the accompanying Consolidated Statements of Operations and Comprehensive Loss. As a result of the Business Combination, the Legacy QuantumScape warrants converted into a warrant to purchase shares of the Company’s common stock converted at the Exchange Ratio. The Company determined the warrants to be equity classified and the fair value of the warrants upon consummation of the Business Combination, as adjusted based on the price of the underlying common stock, was reclassified to additional paid-in
Assumed Common Stock Warrants Liability	Assumed Common Stock Warrants Liability The Company assumed 11,499,989 public warrants (the “Public Warrants”) and 6,650,000 private placement warrants (the “Private Placement Warrants”, and the Public Warrants together with the Private Placement Warrants, the “Assumed Common Stock Warrants”) upon the Business Combination, all of which were issued in connection with Kensington’s initial public offering (other than 75,000 Private Placement Warrants of which that were issued in connection with the closing of the Business Combination, which are referred to as the Working Capital Warrants) and entitle each holder to purchase one share of Class A Common Stock at an exercise price of at $11.50 per share. As of March 31, 2021, 2,010,225 Public Warrants and 6,650,000 Private Placement Warrants are outstanding. The Public Warrants are publicly traded and are exercisable for cash unless certain conditions occur, such as the failure to have an effective registration statement related to the shares issuable upon exercise or redemption by the Company under certain conditions, at which time the warrants may be cashless exercised. The Private Placement Warrants are transferable, assignable or salable in certain limited exceptions. The Private Placement Warrants are exercisable for cash or on a cashless basis, at the holder’s option, and are non-redeemable The Company evaluated the Assumed Common Stock Warrants under ASC 815-40, Derivatives and Hedging—Contracts in Entity’s Own Equity (“ASC 815-40”)
Segments	Segments Operating segments are defined as components of an entity for which separate financial information is available and that is regularly reviewed by the Chief Operating Decision Maker (“CODM”) in deciding how to allocate resources to an individual segment and in assessing performance. The Company’s CODM is its Chief Executive Officer. The Company has determined that it operates in one operating segment and one reportable segment, as the CODM reviews financial information presented on a consolidated basis for purposes of making operating decisions, allocating resources, and evaluating financial performance.	Segments Operating segments are defined as components of an entity for which separate financial information is available and that is regularly reviewed by the Chief Operating Decision Maker (“CODM”) in deciding how to allocate resources to an individual segment and in assessing performance. The Company’s CODM is its Chief Executive Officer. The Company has determined that it operates in one operating segment and one reportable segment, as the CODM reviews financial information presented on a consolidated basis for purposes of making operating decisions, allocating resources, and evaluating financial performance.
Research and Development Cost	Research and Development Cost Costs related to research and development are expensed as incurred.	Research and Development Cost Costs related to research and development are expensed as incurred.
Stock-Based Compensation	Stock-Based Compensation The Company measures and recognizes compensation expense for all stock-based awards made to employees, directors, and non-employees, The fair value of options granted is estimated on the grant date using the Black-Scholes option valuation model. This valuation model for stock-based compensation expense requires the Company to make assumptions and judgments about the variables used in the calculation, including the expected term (weighted-average period of time that the options granted are expected to be outstanding), the volatility of the Company’s common stock, and an assumed risk-free interest rate. The Company accounts for forfeitures when they occur. The Company uses the simplified calculation of the expected life, which takes into consideration the grant’s contractual life and vesting period and assumes that all options will be exercised between the vesting date and the contractual term of the option. No awards have been issued with a market condition or other non-standard Given the lack of public market for the Company’s common stock prior to the Business Combination and the Company’s minimal history as a public company subsequent to the Business Combination, the estimate for volatility is based on an average of the historical volatilities of the common stock of several entities with characteristics similar to those of the Company. Since these comparable companies operate in the same industry segment, the Company expects that it would share similar characteristics, such as risks profiles, volatility, capital intensity, clientele, and market growth patterns and drivers. The risk-free rate is based on the U.S. Treasury yield curve in effect at the time of grant for periods corresponding with the expected life of the option. The Company estimates the fair value of restricted stock units based on the closing price of the Company’s common stock on the date of grant.	Stock-Based Compensation The Company measures and recognizes compensation expense for all stock-based awards made to employees, directors, and non-employees, The fair value of options granted is estimated on the grant date using the Black-Scholes option valuation model. This valuation model for stock-based compensation expense requires the Company to make assumptions and judgments about the variables used in the calculation, including the expected term (weighted-average period of time that the options granted are expected to be outstanding), the volatility of the Company’s common stock, and an assumed risk-free interest rate. The Company accounts for forfeitures when they occur. The Company uses the simplified calculation of the expected life, which takes into consideration the grant’s contractual life and vesting period and assumes that all options will be exercised between the vesting date and the contractual term of the option. No awards have been issued with a market condition or other non-standard Given the lack of public market for the Company’s stock prior to the Business Combination and minimal history as a public company subsequent to the Business Combination, the estimate for volatility is based on an average of the historical volatilities of the common stock of several entities with characteristics similar to those of the Company. Since these comparable companies operate in the same industry segment, the Company expects that it would share similar characteristics, such as risks profiles, volatility, capital intensity, clientele, and market growth patterns and drivers. The risk-free rate is based on the U.S. Treasury yield curve in effect at the time of grant for periods corresponding with the expected life of the option.
Income Taxes	Income Taxes The Company accounts for income taxes under an asset and liability approach. Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes and operating loss carryforwards, measured by applying currently enacted tax laws. Valuation allowances are provided when necessary to reduce net deferred tax assets to an amount that is more likely than not to be realized. The Company recognizes tax liabilities based upon its estimate of whether, and the extent to which, additional taxes will be due when such estimates are more likely than not to be sustained. An uncertain income tax position will not be recognized if it has less than a 50% likelihood of being sustained. The Company has no provision for income taxes for the three months ended March 31, 2021 and 2020. The Company has no current tax expense from losses and no deferred expense from the valuation allowance. The Company’s effective tax rate differs from the U.S. statutory rate primarily due a valuation allowance against its net deferred tax assets as it more likely than not that some or all of the deferred tax assets will not be realized.	Income Taxes The Company accounts for income taxes under an asset and liability approach. Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes and operating loss carryforwards, measured by applying currently enacted tax laws. Valuation allowances are provided when necessary to reduce net deferred tax assets to an amount that is more likely than not to be realized. The Company recognizes tax liabilities based upon its estimate of whether, and the extent to which, additional taxes will be due when such estimates are more likely than not to be sustained. An uncertain income tax position will not be recognized if it has less than a 50% likelihood of being sustained.
Comprehensive Income or Loss	Comprehensive Income or Loss The Company’s comprehensive income or loss consists of net income or loss and other comprehensive loss. Unrealized gains or losses on available-for-sale	Comprehensive Income or Loss The Company’s comprehensive income or loss consists of net income or loss and other comprehensive loss. Unrealized gains or losses on available-for-sale
Net Loss per Share of Common Stock	Net Loss per Share of Common Stock Basic net loss per share is computed by dividing the net loss by the weighted-average number of shares of common stock outstanding during the period. Diluted earnings per share adjusts basic earnings per share for the potentially dilutive impact of stock options and warrants. As the Company has reported losses for all periods presented, all potentially dilutive securities including stock options and warrants, are antidilutive and accordingly, basic net loss per share equals diluted net loss per share.	Net Loss per Share of Common Stock Basic net loss per share is computed by dividing the net loss by the weighted-average number of shares of common stock outstanding during the period. Diluted earnings per share adjusts basic earnings per share for the potentially dilutive impact of stock options and warrants. As the Company has reported losses for all periods presented, all potentially dilutive securities including stock options and warrants, are antidilutive and accordingly, basic net loss per share equals diluted net loss per share.
Immaterial Adjustments		Immaterial Adjustments The Company made an immaterial correcting adjustment (the “correcting adjustment”) to its Consolidated Balance Sheet and Consolidated Statement of Redeemable Non-controlling non-controlling non-controlling
Assumed Common Stock Warrants Liability		Assumed Common Stock Warrants Liability The Company assumed 11,499,989 Public Warrants and 6,650,000 Private Placement Warrants upon the Business Combination, all of which were issued in connection with Kensington’s initial public offering (other than 75,000 Private Placement Warrants of which that were issued in connection with the closing of the Business Combination) and entitle the holder to purchase one share of Class A Common Stock at an exercise price of at $11.50 per share. All of the Assumed Common Stock Warrants remained outstanding as of December 31, 2020. The Public Warrants are publicly traded and are exercisable for cash unless certain conditions occur, such as the failure to have an effective registration statement related to the shares issuable upon exercise or redemption by the Company under certain conditions, at which time the warrants may be cashless exercised. The Private Placement Warrants are transferable, assignable or salable in certain limited exceptions. The Private Placement Warrants are exercisable for cash or on a cashless basis, at the holder’s option, and are non-redeemable The Company evaluated the Assumed Common Stock Warrants under ASC 815-40, Derivatives and Hedging—Contracts in Entity’s Own Equity (“ASC 815-40”)

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Accounting Policies [Abstract]
Summary of Property and Equipment and Their Estimated Useful Lives of Assets	The estimated useful lives of assets are as follows: Computers and hardware 3 years Furniture and fixtures 7 years Lab equipment 5 years Leasehold improvements Shorter of the lease term (including estimated renewals) or the estimated useful lives of the improvements	The estimated useful lives of assets are as follows: Computers and hardware 3 years Furniture and fixtures 7 years Lab equipment 5 years Building and improvements 25 years Leasehold improvements Shorter of the lease term (including estimated renewals) or the estimated useful lives of the improvements

Property and Equipment (Tables)

Property and Equipment (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Property Plant And Equipment [Abstract]
Schedule of Property and Equipment	Property and equipment at March 31, 2021 and December 31, 2020, consisted of the following (amounts in thousands): March 31 December 31 Computers and hardware $ 836 $ 624 Furniture and fixtures 12,006 10,099 Lab equipment 43,342 37,051 Leasehold improvements 12,935 12,154 Construction-in-progress 24,596 16,078 93,715 76,006 Accumulated depreciation and amortization (34,182 ) (32,310 ) Property and equipment, net $ 59,533 $ 43,696	Property and equipment at December 31, 2020 and 2019, consisted of the following (amounts in thousands): December 31, 2020 2019 Computers and hardware $ 624 $ 598 Furniture and fixtures 10,099 4,755 Lab equipment 37,051 25,919 Leasehold improvements 12,154 12,005 Construction-in-progress 16,078 8,610 76,006 51,887 Accumulated depreciation and amortization (32,310 ) (26,395 ) Property and equipment, net $ 43,696 $ 25,492

Leases (Tables)

Leases (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Leases [Abstract]
Summary of Lease Related Expense	The components of lease related expense are as follows (amounts in thousands): Three Months Ended March 31, Operating leases 2021 2020 Operating lease cost $ 596 $ 536 Variable lease cost 104 104 Operating lease expense $ 700 $ 640	The components of lease related expense are as follows (amounts in thousands): Year Ended Operating leases 2020 2019 Operating lease cost $ 2,143 $ 2,143 Variable lease cost 409 425 Operating lease expense $ 2,552 $ 2,568
Summary of Supplemental Cash Flow Information Related to Leases	The components of supplemental cash flow information related to leases are as follows (amounts in thousands): Three Months Ended March 31, 2021 2020 Operating cash flows—operating leases $ 569 $ 496 Right-of-use 690 — Three Months Ended March 31, 2021 2020 Weighted-average remaining lease term—operating leases (in years) 6.7 7.8 Weighted-average discount rate—operating leases 6.90 % 7.00 %	The components of supplemental cash flow information related to leases are as follows (amounts in thousands): Year Ended 2020 2019 Operating cash flows—operating leases $ 1,994 $ 1,936 Right-of-use $ — $ 14,100 Year Ended 2020 2019 Weighted-average remaining lease term—operating leases (in years) 7.1 8.1 Weighted-average discount rate—operating leases 7.00 % 7.00 %
Summary of Future Minimum Payments	As of March 31, 2021, future minimum payments during the next five years and thereafter are as follows (amounts in thousands): Fiscal Year Operating Leases 2021 (remaining nine months) $ 1,719 2022 2,355 2023 2,547 2024 2,344 2025 2,318 Thereafter 4,828 Total 16,111 Less present value discount (3,302 ) Operating lease liabilities $ 12,809	As of December 31, 2020, future minimum payments during the next five years and thereafter are as follows (amounts in thousands): Operating Year Ended December 31, 2021 $ 2,053 Year Ended December 31, 2022 2,115 Year Ended December 31, 2023 2,301 Year Ended December 31, 2024 2,318 Year Ended December 31, 2025 2,318 Thereafter 4,828 Total 15,933 Less present value discount (3,469 ) Operating lease liabilities $ 12,464

Earnings (Loss) Per Share (Tabl

Earnings (Loss) Per Share (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Schedule Of Earnings Per Share Basic And Diluted [Abstract]
Summary of Basic and Diluted Loss per Share of Common Stock	The following table sets forth the computation of basic and diluted loss per Class A Common Stock and Class B Common Stock (amounts in thousands, except share and per share amounts): Three Months Ended March 31, 2021 2020 Numerator: Net loss attributable to common stockholders $ (75,079 ) $ (15,374 ) Denominator: Weighted average Class A and Class B common shares outstanding—Basic and Diluted 368,783,516 239,792,967 Net loss per share attributable to Class A and Class B Common stockholders—Basic and Diluted $ (0.20 ) $ (0.06 )	The following table sets forth the computation of basic and diluted loss per Class A Common Stock and Class B Common Stock (amounts in thousands, except share and per share amounts): Year Ended December 31, 2020 2019 (Restated) Numerator: Net loss attributable to common stockholders $ (1,681,777 ) $ (51,283 ) Denominator: Weighted average Class A and Class B common shares outstanding—Basic and Diluted 252,143,509 239,636,062 Net loss per share attributable to Class A and Class B Common stockholders—Basic and Diluted $ (6.67 ) $ (0.21 )
Summary of Potential Common Stock Outstanding Excluded from Computation of Diluted Net Loss Per Share	The following table presents the potential common stock outstanding that was excluded from the computation of diluted net loss per share of common stock as of the periods presented because including them would have been antidilutive: Three Months Ended March 31, 2021 2020 Warrants 8,660,225 1,022,740 Options outstanding 52,065,063 55,264,709 Restricted stock units (1) 12,473,152 — VGA contingent purchase commitment (2) 15,221,334 — Total 88,419,774 56,287,449 (1) Restricted stock units include 569,752 shares vested but not issued, subject to HSR clearance as of March 31, 2021. (2) This refers to VGA’s commitment to purchase the Second Closing VGA Shares subject to certain conditions including the achievement of an agreed technical milestone on or before March 31, 2021 and the expiration or early termination of the waiting period under HSR. See Note 9 and Note 13 for more information.	The following table presents the potential common stock outstanding that was excluded from the computation of diluted net loss per share of common stock as of the periods presented because including them would have been antidilutive: Year Ended December 31, 2020 2019 Warrants 18,149,989 1,022,740 Options outstanding 55,316,336 55,456,890 Restricted stock units 13,913,076 — VGA contingent purchase commitment (1) 15,221,334 — Total 102,600,735 56,479,630 (1) This refers to VGA’s commitment to purchase 15,221,334 shares of Class A Common Stock for $100.0 million subject to certain conditions including the achievement of a specified technical milestone by March 31, 2021. See Note 11 for more information.

Joint Venture and Redeemable _2

Joint Venture and Redeemable Non-Controlling Interest (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Joint Venture And Non Controlling Interest [Abstract]
Schedule of Change in Redeemable Non-Controlling Interest	The following table sets forth the change in redeemable non-controlling interest Redeemable Non-Controlling Interest Balance as of December 31, 2020 $ 1,704 Net loss attributable to redeemable non-controlling (10 ) Balance as of March 31, 2021 $ 1,694 Redeemable Non-Controlling Interest Balance as of December 31, 2019 $ 1,710 Net loss attributable to redeemable non-controlling (4 ) Balance as of March 31, 2020 $ 1,706	The following table sets forth the change in redeemable non-controlling interest Redeemable Non-Controlling Balance at December 31, 2018 $ 1,690 Net income attributable to redeemable non-controlling 20 Balance at December 31, 2019 $ 1,710 Net loss attributable to redeemable non-controlling (6 ) Balance at December 31, 2020 $ 1,704

Restatement of Consolidated F_2

Restatement of Consolidated Financial Statements (Tables)	12 Months Ended
	Dec. 31, 2020
Accounting Changes And Error Corrections [Abstract]
Impact of the Restatement of Consolidated Financial Statements	The impact of the restatement on the Consolidated Balance Sheet, Consolidated Statement of Operations and Comprehensive Loss and Consolidated Statement of Cash Flows for the year ended December 31, 2020 is presented below. The restatement had no impact on net cash flows from operating, investing or financing activities. As of December 31, 2020 As Restatement As (In Thousands, Except per Share Amounts) Balance Sheet Total current assets $ 1,009,168 $ — $ 1,009,168 Total assets $ 1,066,769 $ — $ 1,066,769 Liabilities, redeemable non-controlling Total current liabilities $ 12,350 $ — $ 12,350 Assumed common stock warrant liabilities — 689,699 689,699 Total liabilities 23,594 689,699 713,293 Redeemable non-controlling 1,704 — 1,704 Stockholders’ equity Preferred stock—$0.0001 par value — — — Common stock—$0.0001 par value 36 — 36 Additional paid-in-capital 2,437,242 (107,836 ) 2,329,406 Accumulated other comprehensive loss (31 ) — (31 ) Accumulated deficit (1,395,776 ) (581,863 ) (1,977,639 ) Total stockholders’ equity 1,041,471 (689,699 ) 351,772 Total liabilities, redeemable non-controlling $ 1,066,769 $ — $ 1,066,769 For the Year Ended December 31, 2020 As Restatement As (In Thousands, Except Share and per Share Statement of Operations and Comprehensive Loss Total operating expenses $ 81,021 $ — $ 81,021 Loss from operations (81,021 ) — (81,021 ) Other (expense) income: Interest expense (20,765 ) — (20,765 ) Interest income 1,093 — 1,093 Change in fair value of Series F convertible preferred stock tranche liabilities (999,987 ) — (999,987 ) Change in fair value of assumed common stock warrant liabilities — (581,863 ) (581,863 ) Other income 760 — 760 Total other expense (1,018,899 ) (581,863 ) (1,600,762 ) Net loss (1,099,920 ) (581,863 ) (1,681,783 ) Less: Net loss attributable to non-controlling (6 ) — (6 ) Net loss attributable to common stockholders $ (1,099,914 ) $ (581,863 ) $ (1,681,777 ) Net loss $ (1,099,920 ) $ (581,863 ) $ (1,681,783 ) Other comprehensive loss: Unrealized loss on marketable securities (121 ) — (121 ) Total comprehensive loss (1,100,041 ) (581,863 ) (1,681,904 ) Less: Comprehensive loss attributable to non-controlling (6 ) — (6 ) Comprehensive loss attributable to common stockholders $ (1,100,035 ) $ (581,863 ) $ (1,681,898 ) Basic and Diluted net loss per share $ (4.36 ) $ (6.67 ) Basic and Diluted weighted-average common shares outstanding 252,143,509 252,143,509 For the Year Ended December 31, 2020 As Restatement As (In Thousands) Statement of Cash Flows Net loss $ (1,099,920 ) $ (581,863 ) $ (1,681,783 ) Adjustments to reconcile net loss to net cash used in operating activities 1,038,657 581,863 1,620,520 Net cash used in operating activities (61,263 ) — (61,263 ) Net cash used in investing activities (802,648 ) — (802,648 ) Net cash provided by financing activities 953,724 — 953,724

Business Combination (Tables)

Business Combination (Tables)	12 Months Ended
	Dec. 31, 2020
Business Combinations [Abstract]
Schedule of Reconciliation of Elements of Business Combination to Consolidated Statement of Cash Flows and Consolidated Statement of Redeemable Non-Controlling Interest and Stockholders' Equity	The following table reconciles the elements of the Business Combination to the Consolidated Statement of Cash Flows and the Consolidated Statement of Redeemable Non-Controlling Recapitalization Cash- Kensington trust and cash, net of redemptions $ 230,128 Cash- PIPE Financing 500,000 Non-cash 592 Less: Fair value of assumed common stock warrants (Restated) 109,081 Less: transaction costs and advisory fees for QuantumScape allocated to equity (Restated) 41,664 Less: transaction costs and advisory fees for Kensington (Restated) 11,372 Net Business Combination (Restated) $ 568,603 Less: non-cash 592 Less: transaction costs and advisory fees for QuantumScape allocated to warrants (Restated) 1,245 Add: Non-cash 109,081 Add: accrued transaction costs and advisor fees 1,016 Net cash contributions from Business Combination $ 676,863
Schedule of Number of Shares of Common Stock Issued Immediately Following Consummation of Business Combination	The number of shares of common stock issued immediately following the consummation of the Business Combination: Number of Common stock, outstanding prior to Business Combination 23,000,000 Less: redemption of Kensington shares 15,255 Common stock of Kensington 22,984,745 Kensington Founder Shares 5,750,000 Shares issued in PIPE Financing 50,000,000 Business Combination and PIPE Financing shares—Class A common stock 78,734,745 Legacy QuantumScape shares—Class A common stock (1) 110,734,478 Legacy QuantumScape shares—Class B common stock (1) 158,301,450 Total shares of common stock immediately after Business Combination 347,770,673 (1) The number of Legacy QuantumScape Class A common stock was determined from the 27,533,913 shares of Legacy QuantumScape Class A common stock outstanding immediately prior to the closing of the Business Combination converted at the Exchange Ratio. All fractional shares were rounded down. (2) The number of Legacy QuantumScape Class B common stock was determined from the 39,361,342 shares of Legacy QuantumScape Class B common stock outstanding immediately prior to the closing of the Business Combination converted at the Exchange Ratio. All fractional shares were rounded down.

Fair Value Measurement (Tables)

Fair Value Measurement (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Summary of Financial Assets and Liabilities Subject to Fair Value Measurements on Recurring Basis	The Company’s financial assets and liabilities subject to fair value measurements on a recurring basis and the level of inputs used for such measurements were as follows (amounts in thousands): Fair Value Measured as of March 31, 2021 Level 1 Level 2 Level 3 Total Assets included in: Money market fund (1) $ 755,825 $ — $ — $ 755,825 Marketable securities (2) — 771,101 — 771,101 Total fair value $ 755,825 $ 771,101 $ — $ 1,526,926 Liabilities included in: Assumed common stock warrants (Public) $ 66,860 $ — $ — $ 66,860 Assumed common stock warrants (Private Placement) — 221,179 — 221,179 Total fair value $ 66,860 $ 221,179 $ — $ 288,039 Fair Value Measured as of Level 1 Level 2 Level 3 Total Assets included in: Money market fund (1) $ 12,235 $ — $ — $ 12,235 Marketable securities (2) — 977,326 — 977,326 Total fair value $ 12,235 $ 977,326 $ — $ 989,561 Liabilities included in: Assumed common stock warrants (Public) $ 436,999 $ — $ — $ 436,999 Assumed common stock warrants (Private Placement) — 252,700 — 252,700 Total fair value $ 436,999 $ 252,700 $ — $ 689,699 (1) Money market funds are included in cash and cash equivalents on the Condensed Consolidated Balance Sheet. (2) As of December 31, 2020, marketable securities with original maturities of three months or less of $105.2 million, are included in cash and cash equivalents on the Condensed Consolidated Balance Sheet. As of March 31, 2021, there were no marketable securities with original maturities of three months or less included in cash and cash equivalents on the Condensed Consolidated Balance Sheet.	The Company’s financial assets and liabilities subject to fair value measurements on a recurring basis and the level of inputs used for such measurements were as follows (amounts in thousands): Fair Value Measured as of Level 1 Level 2 Level 3 Total Assets included in: Money market fund (1) $ 12,235 $ — $ — $ 12,235 Marketable securities (2) — 977,326 — 977,326 Total fair value $ 12,235 $ 977,326 $ — $ 989,561 Liabilities included in: Assumed common stock warrants (Public) (Restated) $ 436,999 $ — $ — $ 436,999 Assumed common stock warrants (Private Placement) (Restated) — 252,700 — 252,700 Total fair value (Restated) $ 436,999 $ 252,700 $ — $ 689,699 Fair Value Measured as of Level 1 Level 2 Level 3 Total Assets included in: Money market fund (1) $ 5,163 $ — $ — $ 5,163 Marketable securities (2) — 120,599 — 120,599 Total fair value $ 5,163 $ 120,599 $ — $ 125,762 Liabilities included in: Convertible preferred stock warrant liabilities $ — $ — $ 1,860 $ 1,860 Total fair value $ — $ — $ 1,860 $ 1,860 (1) Money market funds are included in Cash and cash equivalents on the Consolidated Balance Sheet. (2) Marketable securities with original maturities of three months or less, in the amount of $105.2 million and $18.7 million, are included in Cash and cash equivalents on the Consolidated Balance Sheet as of December 31, 2020 and December 31, 2019, respectively.
Summary of Major Security Type Assets That Measured at Fair Value on Recurring Basis	The fair value as of March 31, 2021 and December 31, 2020, are as follows (amounts in thousands): March 31, 2021 Amortized Cost Unrealized Gain Unrealized Loss Fair Value Level 1 securities Money market fund $ 755,825 $ — $ — $ 755,825 Level 2 securities US government securities 770,958 143 — 771,101 Total $ 1,526,783 $ 143 $ — $ 1,526,926 December 31, 2020 Amortized Cost Unrealized Gain Unrealized Loss Fair Value Level 1 securities Money market fund $ 12,235 $ — $ — $ 12,235 Level 2 securities US government securities 977,357 24 (55 ) 977,326 Total $ 989,592 $ 24 $ (55 ) $ 989,561	The following table summarizes, by major security type, the Company’s assets that are measured at fair value on a recurring basis and are categorized using the fair value hierarchy. Amortized cost net of unrealized gain (loss) is equal to fair value as of December 31, 2020. The fair value as of December 31, 2020 and 2019, are as follows (amounts in thousands): December 31, 2020 Amortized Cost Unrealized Unrealized Fair Value Level 1 securities Money market fund $ 12,235 $ — $ — $ 12,235 Level 2 securities US government securities 977,357 24 (55 ) 977,326 Total $ 989,592 $ 24 $ (55 ) $ 989,561 December 31, 2019 Amortized Cost Unrealized Unrealized Fair Value Level 1 securities Money market fund $ 5,163 $ — $ — $ 5,163 Level 2 securities Repurchase agreement 13,500 — — 13,500 US government securities 107,009 90 — 107,099 Total Level 2 securities 120,509 90 — 120,599 Total $ 125,672 $ 90 $ — $ 125,762
Summary of Estimated Amortized Cost and Fair Value of Available-for-Sale Securities by Contractual Maturity	The estimated amortized cost and fair value of available-for-sale March 31, 2021 December 31, 2020 Amortized Fair Value Amortized Fair Value Due within one year $ 1,526,783 $ 1,526,926 $ 895,867 $ 895,830 Due after one year and through five years — — 93,725 93,731 Total $ 1,526,783 $ 1,526,926 $ 989,592 $ 989,561	The estimated amortized cost and fair value of available-for-sale December 31, 2020 Amortized Cost Fair Value Due within one year $ 895,867 $ 895,830 Due after one year and through five years 93,725 93,731 Total $ 989,592 $ 989,561
Summary of Fair Value of Warrants Re-measured Using OPM		Upon the closing the Business Combination and conversion to warrants for the purchase if Class A Common Stock, the fair value of the TPC1 and TPC2 warrants were determined using the OPM with the following assumptions: At Conversion TPC1 Warrants TPC2 Warrants Option term (in years) 5 5 Volatility 70.0 % 70.0 % Risk-free interest rate 0.39 % 0.39 % Expected dividends — — Discount for lack of marketability — — In December 2020, all outstanding TPC1 and TPC2 warrants were net exercised in exchange for 998,460 shares of Class A Common Stock. As of December 31, 2019, the fair value of the TPC1 and TPC2 warrants were re-measured As of December 31, 2019 TPC1 Warrants TPC2 Warrants Option term (in years) 5 5 Volatility 58.5 % 45.0 % Risk-free interest rate 1.69 % 1.69 % Expected dividends — — Discount for lack of marketability 35.0 % 35.0 %
Series F Convertible Preferred Stock
Schedule of Reconciliation of Warrants and Tranche Liabilities Measured and Recorded at Fair Value on Recurring Basis Using Significant Unobservable Inputs		The following table presents the reconciliation of the Series F convertible preferred tranche liabilities measured and recorded at fair value on a recurring basis using the significant unobservable inputs described above (amounts in thousands): Fair Value Balance at December 31, 2019 $ — Issuance and re-measurement 999,865 Issuance of Legacy QuantumScape Series F Preferred Stock—tranche shares 3 and 4 (484,471 ) Reclassification to additional paid-in (515,394 ) Balance at December 31, 2020 $ —
TPC Warrants
Schedule of Reconciliation of Warrants and Tranche Liabilities Measured and Recorded at Fair Value on Recurring Basis Using Significant Unobservable Inputs		The following table presents the reconciliation of the TPC warrants measured and recorded at fair value on a recurring basis using the significant unobservable inputs described above (amounts in thousands): TPC1 TPC2 Fair Value Balance at December 31, 2018 $ 984 $ 782 $ 1,766 Re-measurement 52 42 94 Balance at December 31, 2019 1,036 824 1,860 Re-measurement 10,475 10,290 20,765 Reclassification to additional paid-in (11,511 ) (11,114 ) (22,625 ) Balance at December 31, 2020 $ — $ — $ —

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Stockholders Equity Note [Abstract]
Schedule of Stock Option Activity	Stock option activity under the Plans during the three months ended March 31, 2021 is as follows: Number of Shares Outstanding Weighted Average Exercise Weighted Average Remaining Contractual Term (Years) Intrinsic (in thousands) Balance as of December 31, 2020 55,316,336 $ 1.62 5.77 Cancelled and forfeited (366,724 ) 2.34 — Exercised (2,884,549 ) 0.30 — Balance as of March 31, 2021 52,065,063 $ 1.69 5.77 $ 2,242,170 Vested and exercisable -March 31, 2021 41,102,851 $ 1.26 5.04 $ 1,787,418	Stock option activity under the Plans are as follows: Number of Weighted Weighted Intrinsic Balance at December 31, 2018 (as previously reported) 11,112,466 $ 4.15 6.44 Conversion of awards due to recapitalization 33,578,834 (3.12 ) Balance at December 31, 2018, effect of reverse acquisition 44,691,300 1.03 6.44 Granted 11,955,658 2.38 Cancelled and forfeited (571,664 ) 1.43 Exercised (618,404 ) 0.64 Balance at December 31, 2019 55,456,890 $ 1.32 6.32 Granted 3,866,992 5.08 Cancelled and forfeited (3,361,530 ) 0.85 Exercised (646,016 ) 0.93 Balance at December 31, 2020 55,316,336 $ 1.62 5.77 $ 4,582,001 Vested and exercisable —December 31, 2020 41,944,514 $ 1.17 4.88 $ 3,493,198
Schedule of Additional Information Regarding Options Outstanding	Additional information regarding options outstanding at March 31, 2021, is as follows: Range of Exercise Price per Share Number of Options Outstanding Weighted Average Exercise Price Weighted Average Remaining Contractual Life (Years) $0.11 - $0.64 7,910,607 $ 0.49 1.73 $1.05 - $1.35 27,952,167 1.25 5.34 $2.38 13,515,675 2.38 8.32 $6.23 2,686,614 6.23 9.43 52,065,063 $ 1.69 5.77	Additional information regarding options outstanding at December 31, 2020, is as follows: Range of Exercise Price per Share Number of Options Weighted Average Weighted Average $0.11 - $0.64 10,380,188 $ 0.40 1.56 $1.05 - $1.35 28,295,781 1.25 5.57 $2.38 13,953,743 2.38 8.56 $6.23 2,686,624 6.23 9.68 55,316,336 $ 1.62 5.77
Schedule of Weighted Average Assumptions Used Inputs to Black-Scholes OPM		The following weighted average assumptions were used as inputs to the Black-Scholes OPM in determining the estimated grant-date fair value of the Company’s stock options to employees: Year Ended 2020 2019 Volatility 70.00 % 70.00 % Risk-free interest rate 0.39 % 1.92 % Expected term (in years) 6.08 6.02 Expected dividend — — Weighted average fair value at grant date $ 2.67 $ 1.50
Schedule of Restricted Stock Unit Activity	Restricted stock unit activity under the Plans are as follows: Number of Restricted Stock Units Weighted Average grant date fair value Balance as of December 31, 2020 13,913,076 $ 8.94 Granted 351,584 46.89 Vested (2,014,071 ) 4.83 Forfeited (347,189 ) 6.62 Balance as of March 31, 2021 11,903,400 $ 10.83	Restricted stock unit activity under the Plans are as follows: Number of Weighted Balance at December 31, 2019 — $ — Granted 13,913,076 8.94 Balance at December 31, 2020 13,913,076 $ 8.94 Vested—December 31, 2020 —
Schedule of Stock-based Compensation Expense	Total stock-based compensation expense recognized in the accompanying Condensed Consolidated Statements of Operations and Comprehensive Loss for all equity awards is as follows (amounts in thousands): Three Months Ended March 31, 2021 2020 Research and development $ 6,367 $ 1,356 General and administrative 5,309 841 Total stock-based compensation expense $ 11,676 $ 2,197	Total stock-based compensation expense recognized in the accompanying Consolidated Statements of Operations and Comprehensive Loss for all equity awards is as follows (amounts in thousands): Year Ended 2020 2019 Research and development $ 9,889 $ 4,115 General and administrative 7,135 2,696 Total stock-based compensation expense $ 17,024 $ 6,811

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Schedule of Reconciliation of Effective Income Tax Rate	A reconciliation from U.S. statutory rate of 21% to the effective rate is as follows: Year Ended December 31, 2020 2019 (Restated) Federal Statutory rate 21.0 % 21.0 % State tax expense 0.0 % 7.0 % Permanent tax items (0.2 %) (2.2 %) R&D tax credit 0.2 % 4.5 % Other (0.1 %) 0.0 % Change to valuation allowance (1.1 %) (30.4 %) Change in fair value of assumed common stock warrant liabilities (7.3 %) 0.0 % Change in fair value of Series F tranche liabilities (12.5 %) 0.0 % Effective tax rate 0.0 % 0.0 %
Components of Net Deferred Tax Assets	Significant components of the Company’s net deferred tax assets as of December 31, 2020 and 2019, are as follows (amounts in thousands): Year Ended 2020 2019 Deferred tax assets: Net operating losses $ 88,392 $ 71,374 Tax credits 16,314 10,219 Accruals and stock-based compensation 3,313 4,671 Lease liability 2,621 3,796 Intangibles 1,413 90 Gross deferred tax assets 112,053 90,150 Valuation allowance (105,781 ) (85,677 ) Total deferred tax assets $ 6,272 $ 4,473 Deferred tax liabilities: Right of use assets $ (2,463 ) (3,627 ) Fixed assets (3,809 ) (846 ) Total deferred tax liabilities (6,272 ) (4,473 ) Total net deferred tax assets $ — $ —
Reconciliation of Beginning and Ending Balances of Valuation Allowance	A reconciliation of the beginning and ending balances of the valuation allowance is as follows (amounts in thousands): Year Ended December 31, 2020 2019 Beginning of the year $ (85,677 ) $ (71,340 ) Increase (20,104 ) (14,337 ) End of the year $ (105,781 ) $ (85,677 )
Reconciliation of Beginning and Ending Balances of Unrecognized Tax Benefits	A reconciliation of the beginning and ending balances of unrecognized tax benefits is as follows (amounts in thousands): Year Ended December 31, 2020 2019 Beginning of the year $ 7,076 $ 5,372 Increase—current year positions 1,553 1,704 Increase—prior year positions 193 — Decrease—prior year positions (2,247 ) — End of the year $ 6,575 $ 7,076

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2021USD ($)Segment$ / sharesshares	Mar. 31, 2020USD ($)	Dec. 31, 2020USD ($)Segment$ / sharesshares	Dec. 31, 2019USD ($)	Feb. 13, 2021shares	Dec. 31, 2018USD ($)	Sep. 30, 2018Agreement
Summary Of Significant Accounting Policies [Line Items]
Goodwill or other intangible assets	$ 0		$ 0
Number of operating agreements of joint venture parties | Agreement							2
Restricted cash	2,200,000		2,200,000	$ 2,800,000
Amortization of strategic premium	$ 151,000	$ 164,000	$ 655,000	873,000
Warrants outstanding | shares	8,660,225		18,149,989
Number of reportable segment | Segment	1		1
Number of operating segment | Segment	1		1
Awards issued with market condition or other non-standard terms | shares	0		0
Income tax expense (benefit)	$ 0	0	$ 0	0
Current income tax expense (benefit)	0	0	0	0
Deferred income tax expense (benefit)	0	0	0	0
Redeemable non-controlling interest	$ 1,694,000	1,706,000	$ 1,704,000	1,710,000		$ 1,690,000
Public Warrants
Summary Of Significant Accounting Policies [Line Items]
Warrants sold | shares	11,499,989
Warrant exercisable number of shares | shares	1				1
Warrants exercise price per share | $ / shares	$ 11.50		$ 11.50
Warrants outstanding | shares	2,010,225		11,499,989
Minimum percentage of class A stockholders required for settlement of shares	50.00%
Private Placement Warrants
Summary Of Significant Accounting Policies [Line Items]
Warrants sold | shares	6,650,000
Warrant issued in connection with the closing of business combination | shares	75,000
Warrants outstanding | shares	6,650,000
Private Warrants
Summary Of Significant Accounting Policies [Line Items]
Warrant issued in connection with the closing of business combination | shares			75,000
Warrants outstanding | shares			6,650,000
Series D Convertible Preferred Stock
Summary Of Significant Accounting Policies [Line Items]
Net proceeds from issuance convertible preferred stock	$ 59,700,000		$ 59,700,000
Net proceeds from convertible preferred stock strategic premium	7,900,000		7,900,000
Amortization of strategic premium	200,000	$ 200,000	700,000	$ 900,000
Pledged as Security for Facility Lease Agreement
Summary Of Significant Accounting Policies [Line Items]
Restricted cash	2,000,000		2,000,000
Collateral for Commercial Letter Of Credit
Summary Of Significant Accounting Policies [Line Items]
Restricted cash	200,000		200,000
US Government Money Market Fund and Marketable Securities
Summary Of Significant Accounting Policies [Line Items]
Investment securities	755,800,000		12,200,000
US Government and Agency Securities
Summary Of Significant Accounting Policies [Line Items]
Investment securities	$ 771,100,000		$ 977,300,000
JVA
Summary Of Significant Accounting Policies [Line Items]
Percentage of joint venture holders voting interest	13.70%		13.20%	13.10%
Contribution in exchange for equity interests	$ 1,700,000		$ 1,700,000
Equity interests percentage	50.00%		50.00%

Business Combination - Addition

Business Combination - Additional Information (Details) $ / shares in Units, $ in Millions	Nov. 25, 2020Vote$ / sharesshares	Sep. 02, 2020USD ($)$ / sharesshares	Mar. 31, 2021$ / sharesshares	Dec. 31, 2020$ / sharesshares	Dec. 31, 2019$ / sharesshares
Business Combination [Line Items]
Business combination, effective date of acquisition			Nov. 25, 2020	Nov. 25, 2020
Business combination, date of acquisition agreement			Sep. 2, 2020	Sep. 2, 2020
Common stock, par value | $ / shares	$ 0.0001			$ 0.0001
Capital stock, shares authorized | shares	1,350,000,000
Common stock, authorized | shares			1,250,000,000	1,250,000,000	1,250,000,000
Preferred stock, authorized | shares	100,000,000		100,000,000	100,000,000	100,000,000
Number of votes each shareholder entitled			The holder of each share of Class A Common Stock is entitled to one vote, and the holder of each share of Class B Common Stock is entitled to ten votes.
Legacy Quantum Scape
Business Combination [Line Items]
Business combination exchange ratio		4.02175014920
Class A Common Stock
Business Combination [Line Items]
Common stock, par value | $ / shares			$ 0.0001	$ 0.0001	$ 0.0001
Common stock, authorized | shares	1,000,000,000		1,000,000,000	1,000,000,000	1,000,000,000
Number of votes each shareholder entitled	one vote
Number of votes each shareholder entitled | Vote	1
Class A Common Stock | Subscription Agreement
Business Combination [Line Items]
Aggregate number of shares sold | shares		50,000,000
Aggregate purchase price per share | $ / shares		$ 10
Aggregate purchase price | $		$ 500
Class A Common Stock | Legacy Quantum Scape
Business Combination [Line Items]
Common stock, par value | $ / shares		$ 0.0001
Class B Common Stock
Business Combination [Line Items]
Common stock, par value | $ / shares			$ 0.0001	$ 0.0001	$ 0.0001
Common stock, authorized | shares	250,000,000		250,000,000	250,000,000	250,000,000
Number of votes each shareholder entitled	ten votes
Number of votes each shareholder entitled | Vote	10
Class B Common Stock | Legacy Quantum Scape
Business Combination [Line Items]
Common stock, par value | $ / shares		$ 0.0001

Fair Value Measurement - Summar

Fair Value Measurement - Summary of Financial Assets and Liabilities Subject to Fair Value Measurements on Recurring Basis (Parenthetical) (Details) - USD ($)	Mar. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Marketable securities	$ 0	$ 105,200,000	$ 18,700,000

Fair Value Measurement - Summ_2

Fair Value Measurement - Summary of Estimated Amortized Cost and Fair Value of Available-for-Sale Securities by Contractual Maturity (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Investments Debt And Equity Securities [Abstract]
Amortized Cost, Due within one year	$ 1,526,783	$ 895,867
Amortized Cost, Due after one year and through five years		93,725
Total Amortized Cost	1,526,783	989,592
Fair Value, Due within one year	1,526,926	895,830
Fair Value, Due after one year and through five years		93,731
Total Fair Value	$ 1,526,926	$ 989,561

Property and Equipment - Schedu

Property and Equipment - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 93,715	$ 76,006	$ 51,887
Accumulated depreciation and amortization	(34,182)	(32,310)	(26,395)
Property and equipment, net	59,533	43,696	25,492
Computers and Hardware
Property Plant And Equipment [Line Items]
Property and equipment, gross	836	624	598
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Property and equipment, gross	12,006	10,099	4,755
Lab Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	43,342	37,051	25,919
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	12,935	12,154	12,005
Construction in Progress
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 24,596	$ 16,078	$ 8,610

Property and Equipment - Additi

Property and Equipment - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Property Plant And Equipment [Abstract]
Depreciation and amortization expense related to property and equipment	$ 2.2	$ 1.4	$ 7.5	$ 5.6

Leases - Summary of Lease Relat

Leases - Summary of Lease Related Expense (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Operating leases
Operating lease cost	$ 596	$ 536	$ 2,143	$ 2,143
Variable lease cost	104	104	409	425
Operating lease expense	$ 700	$ 640	$ 2,552	$ 2,568

Leases - Summary of Supplementa

Leases - Summary of Supplemental Cash Flow Information Related to Leases (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Operating cash flows - operating leases	$ 569	$ 496	$ 1,994	$ 1,936
Right-of-use assets obtained in exchange for operating lease liabilities	$ 690			$ 14,100
Weighted-average remaining lease term - operating leases (in years)	6 years 8 months 12 days	7 years 9 months 18 days	7 years 1 month 6 days	8 years 1 month 6 days
Weighted-average discount rate - operating leases	6.90%	7.00%	7.00%	7.00%

Leases - Summary of Future Mini

Leases - Summary of Future Minimum Payments (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Leases [Abstract]
2021 (remaining nine months)	$ 1,719
Year Ended December 31, 2021	2,355	$ 2,053
Year Ended December 31, 2022	2,547	2,115
Year Ended December 31, 2023	2,344	2,301
Year Ended December 31, 2024	2,318	2,318
Thereafter	4,828
Total	16,111	15,933
Less present value discount	(3,302)	(3,469)
Operating lease liabilities	$ 12,809	12,464
Year Ended December 31, 2025		2,318
Thereafter		$ 4,828

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) - USD ($)	Apr. 28, 2021	Mar. 30, 2021	Dec. 31, 2020	Dec. 01, 2020	Nov. 25, 2020	Jul. 31, 2020	Mar. 31, 2021	Aug. 31, 2020	Mar. 31, 2021	Mar. 31, 2020	Sep. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Nov. 24, 2020
Class of Stock [Line Items]
Shares authorized			1,350,000,000				1,350,000,000		1,350,000,000			1,350,000,000
Common stock, authorized			1,250,000,000				1,250,000,000		1,250,000,000			1,250,000,000	1,250,000,000
Common stock, par value			$ 0.0001		$ 0.0001							$ 0.0001
Preferred stock, authorized			100,000,000		100,000,000		100,000,000		100,000,000			100,000,000	100,000,000
Preferred stock, par value			$ 0.0001				$ 0.0001		$ 0.0001			$ 0.0001	$ 0.0001
Number of votes each shareholder entitled									The holder of each share of Class A Common Stock is entitled to one vote, and the holder of each share of Class B Common Stock is entitled to ten votes.
Common stock, issued					347,770,673
Proceeds from common stock									$ 463,825,000			$ 99,800,000
Preferred stock, shares issued			0				0		0			0	0
Proceeds from issuance of Series F preferred stock, net of issuance costs												$ 176,462,000
Options vesting period									4 years			4 years
Granted (in shares)									0	0		3,866,992	11,955,658
Aggregate intrinsic value									$ 130,600,000	$ 30,000		$ 3,500,000
Stock-based compensation unvested stock options not yet recognized			$ 22,000,000				$ 18,800,000		$ 18,800,000			$ 22,000,000
Expected to be recognized estimated weighted average period									3 years			3 years 1 month 6 days
Common stock, outstanding					22,984,745									23,000,000
Exercise of stock option, Shares									2,884,549			646,016	618,404
Options with fair value vested												$ 9,100,000	$ 6,800,000
Restricted Stock Unit
Class of Stock [Line Items]
Expected to be recognized estimated weighted average period									3 years 3 months 18 days			3 years 6 months
Fair value of restricted stock vested									$ 110,000,000	$ 0
Fair value of restricted stock vested but not issued									569,752
Restricted stock units granted						0			351,584			13,913,076
Unrecognized compensation costs			$ 116,800,000				$ 122,000,000		$ 122,000,000			$ 116,800,000
2020 Equity Incentive Award Plan
Class of Stock [Line Items]
Options is granted to stockholder, percentage									10.00%			10.00%
Options vesting period									4 years			4 years
Options contractual terms									10 years			10 years
Minimum | 2020 Equity Incentive Award Plan
Class of Stock [Line Items]
Options granted price per share									100.00%			100.00%
Options purchase or exercise price per share									110.00%			110.00%
HSR | Subsequent Event
Class of Stock [Line Items]
Proceeds from common stock	$ 100,000,000
Series F Preferred Stock
Class of Stock [Line Items]
Stock issuance costs								$ 11,500,000
Preferred stock, shares issued								7,115,335			14,684,843
Convertible preferred stock price per share											$ 26.4218
Proceeds from issuance of Series F preferred stock, net of issuance costs								$ 188,000,000			$ 388,000,000
Class A Common Stock
Class of Stock [Line Items]
Common stock, authorized			1,000,000,000		1,000,000,000		1,000,000,000		1,000,000,000			1,000,000,000	1,000,000,000
Common stock, par value			$ 0.0001				$ 0.0001		$ 0.0001			$ 0.0001	$ 0.0001
Number of votes each shareholder entitled					one vote
Common stock, issued			207,769,091				233,610,488		233,610,488			207,769,091	81,720,530
Stock issuance costs												$ 200,000
Common stock, outstanding			207,769,091				233,610,488		233,610,488			207,769,091	81,720,530
Class A Common Stock | 2020 Equity Incentive Award Plan
Class of Stock [Line Items]
Common stock authorized for issuance			41,500,000				41,500,000		41,500,000			41,500,000
Common Stock are available for future issuance			59,625,395									59,625,395
Class A Common Stock | Maximum [Member] | 2020 Equity Incentive Award Plan
Class of Stock [Line Items]
Additional common stock authorized for issuance									69,846,580			69,846,580
Class A Common Stock | VGA
Class of Stock [Line Items]
Common stock, issued		15,221,334	15,221,334	15,221,334								15,221,334
Proceeds from common stock		$ 100,000,000	$ 100,000,000	$ 100,000,000								$ 100,000,000
Class A Common Stock | VGA | Subsequent Event
Class of Stock [Line Items]
Proceeds from common stock	$ 100,000,000
Class A Common Stock | March 2021 Public Offering
Class of Stock [Line Items]
Common stock, issued							11,960,000		11,960,000
Stock issuance costs							$ 15,500,000
Proceeds from common stock							$ 462,900,000
Class B Common Stock
Class of Stock [Line Items]
Common stock, authorized			250,000,000		250,000,000		250,000,000		250,000,000			250,000,000	250,000,000
Common stock, par value			$ 0.0001				$ 0.0001		$ 0.0001			$ 0.0001	$ 0.0001
Number of votes each shareholder entitled					ten votes
Common stock, issued			156,224,614				156,161,849		156,161,849			156,224,614	158,056,527
Common stock, outstanding			156,224,614				156,161,849		156,161,849			156,224,614	158,056,527

Stockholders Equity - Schedule

Stockholders Equity - Schedule of Additional Information Regarding Options Outstanding (Details) - $ / shares	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Number of Options Outstanding	52,065,063	55,316,336
Weighted Average Exercise Price	$ 1.69	$ 1.62	$ 1.32	$ 1.03
Weighted Average Remaining Contractual Life (Years)	5 years 9 months 7 days	5 years 9 months 7 days
$0.11 - $0.64
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Number of Options Outstanding	7,910,607	10,380,188
Weighted Average Exercise Price	$ 0.49	$ 0.40
Weighted Average Remaining Contractual Life (Years)	1 year 8 months 23 days	1 year 6 months 21 days
$0.11 - $0.64 | Minimum
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Range of Exercise Price per Share	$ 0.11	$ 0.11
$0.11 - $0.64 | Maximum [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Range of Exercise Price per Share	$ 0.64	$ 0.64
$1.05 - $1.35
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Number of Options Outstanding	27,952,167	28,295,781
Weighted Average Exercise Price	$ 1.25	$ 1.25
Weighted Average Remaining Contractual Life (Years)	5 years 4 months 2 days	5 years 6 months 25 days
$1.05 - $1.35 | Minimum
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Range of Exercise Price per Share	$ 1.05	$ 1.05
$1.05 - $1.35 | Maximum [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Range of Exercise Price per Share	1.35	1.35
$2.38
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Range of Exercise Price per Share	$ 2.38	$ 2.38
Number of Options Outstanding	13,515,675	13,953,743
Weighted Average Exercise Price	$ 2.38	$ 2.38
Weighted Average Remaining Contractual Life (Years)	8 years 3 months 25 days	8 years 6 months 21 days
$6.23
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Range of Exercise Price per Share	$ 6.23	$ 6.23
Number of Options Outstanding	2,686,614	2,686,624
Weighted Average Exercise Price	$ 6.23	$ 6.23
Weighted Average Remaining Contractual Life (Years)	9 years 5 months 4 days	9 years 8 months 4 days

Stockholders' Equity - Schedule

Stockholders' Equity - Schedule of Restricted Stock Unit Activity (Details) - Restricted Stock Unit - $ / shares	Jul. 31, 2020	Mar. 31, 2021	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Restricted Stock Units, Beginning Balance		13,913,076
Number of Restricted Stock Units, Granted	0	351,584	13,913,076
Number of Restricted Stock Units, Vested		(2,014,071)
Number of Restricted Stock Units, Forfeited		(347,189)
Number of Restricted Stock Units, Ending Balance		11,903,400	13,913,076
Weighted Average grant date fair value, Beginning Balance		$ 8.94
Weighted Average grant date fair value, Granted		46.89	$ 8.94
Weighted Average grant date fair value, Vested		4.83
Weighted Average grant date fair value, Forfeited		6.62
Weighted Average grant date fair value, Ending Balance		$ 10.83	$ 8.94

Stockholders Equity - Schedul_2

Stockholders Equity - Schedule of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 11,676	$ 2,197	$ 17,024	$ 6,811
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	6,367	1,356	9,889	4,115
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 5,309	$ 841	$ 7,135	$ 2,696

Earnings (Loss) Per Share - Sum

Earnings (Loss) Per Share - Summary of Basic and Diluted Loss per Share of Common Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Numerator:
Net loss attributable to common stockholders	$ (75,079)	$ (15,374)	$ (1,681,777)	$ (51,283)
Denominator:
Basic and Diluted weighted-average common shares outstanding	368,783,516	239,792,967	252,143,509	239,636,062
Basic and Diluted net loss per share	$ (0.20)	$ (0.06)	$ (6.67)	$ (0.21)
Common Class A and Class B Shares
Denominator:
Basic and Diluted weighted-average common shares outstanding	368,783,516	239,792,967	252,143,509	239,636,062
Basic and Diluted net loss per share	$ (0.20)	$ (0.06)	$ (6.67)	$ (0.21)

Earnings (Loss) Per Share - S_2

Earnings (Loss) Per Share - Summary of Potential Common Stock Outstanding Excluded from Computation of Diluted Net Loss Per Share (Details) - shares	3 Months Ended			12 Months Ended
	Mar. 31, 2021		Mar. 31, 2020	Dec. 31, 2020		Dec. 31, 2019
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive	88,419,774		56,287,449	102,600,735		56,479,630
Warrants
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive	8,660,225		1,022,740	18,149,989		1,022,740
Options Outstanding
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive	52,065,063		55,264,709	55,316,336		55,456,890
Restricted Stock Unit
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive	12,473,152	[1],[2]		13,913,076
VGA Contingent Purchase Commitment
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive	15,221,334	[3]		15,221,334	[1],[2]
[1]	Restricted stock units include 569,752 shares vested but not issued, subject to HSR clearance as of March 31, 2021.
[2]	This refers to VGA’s commitment to purchase 15,221,334 shares of Class A Common Stock for $100.0 million subject to certain conditions including the achievement of a specified technical milestone by March 31, 2021. See Note 11 for more information
[3]	This refers to VGA’s commitment to purchase the Second Closing VGA Shares subject to certain conditions including the achievement of an agreed technical milestone on or before March 31, 2021 and the expiration or early termination of the waiting period under HSR. See Note 9 and Note 13 for more information.

Earnings (Loss) Per Share - S_3

Earnings (Loss) Per Share - Summary of Potential Common Stock Outstanding Excluded from Computation of Diluted Net Loss Per Share (Parenthetical) (Details) - USD ($) $ in Thousands	Mar. 30, 2021	Dec. 31, 2020	Dec. 01, 2020	Mar. 31, 2021	Dec. 31, 2020	Nov. 25, 2020	Dec. 31, 2019
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Common stock, issued						347,770,673
Proceeds from issuance of Class A Common Stock pursuant to Legacy QuantumScape Series F Preferred Stock Purchase Agreement, net of issuance costs				$ 463,825	$ 99,800
Restricted Stock Unit
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Shares vested but not issued				569,752
Class A Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Common stock, issued		207,769,091		233,610,488	207,769,091		81,720,530
Class A Common Stock | VGA
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Common stock, issued	15,221,334	15,221,334	15,221,334		15,221,334
Proceeds from issuance of Class A Common Stock pursuant to Legacy QuantumScape Series F Preferred Stock Purchase Agreement, net of issuance costs	$ 100,000	$ 100,000	$ 100,000		$ 100,000

Joint Venture and Redeemable _3

Joint Venture and Redeemable Non-Controlling Interest - Additional Information (Details) - USD ($) $ in Thousands	May 14, 2020	Sep. 30, 2020	Aug. 31, 2020	Sep. 30, 2020	Dec. 31, 2020	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2019
Joint Venture And Non Controlling Interest [Line Items]
Cash and cash equivalents					$ 113,216	$ 762,341	$ 39,001	$ 22,822
Proceeds from issuance of Series F preferred stock, net of issuance costs					176,462
Series F Preferred Stock
Joint Venture And Non Controlling Interest [Line Items]
Proceeds from issuance of Series F preferred stock, net of issuance costs			$ 188,000	$ 388,000
QSV
Joint Venture And Non Controlling Interest [Line Items]
Cash and cash equivalents					3,406	3,381		3,409
Prepaid expense					$ 100	$ 100		$ 100
QSV | Series F Convertible Preferred Stock
Joint Venture And Non Controlling Interest [Line Items]
Proceeds from issuance of Series F preferred stock, net of issuance costs	$ 200,000
VWGoA | Series F Preferred Stock
Joint Venture And Non Controlling Interest [Line Items]
Proceed from Series F preferred stock financings and business combination		$ 134,000

Joint Venture and Redeemable _4

Joint Venture and Redeemable Non-Controlling Interest - Schedule of Change in Redeemable Non-Controlling Interest (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Redeemable Non-Controlling, Beginning balance	$ 1,704	$ 1,710	$ 1,710	$ 1,690
Net income (loss) attributable to redeemable non-controlling interest in consolidated JV	(10)	(4)	(6)	20
Redeemable Non-Controlling, Ending balance	1,694	1,706	1,704	1,710
Scenario Previously Reported [Member]
Redeemable Non-Controlling, Beginning balance	$ 1,704	$ 1,700	1,700	1,690
Net income (loss) attributable to redeemable non-controlling interest in consolidated JV			(6)
Redeemable Non-Controlling, Ending balance			$ 1,704	$ 1,700

Subsequent Events - Additional

Subsequent Events - Additional Information (Details)	Apr. 28, 2021USD ($)	Apr. 02, 2021USD ($)ft²	Mar. 30, 2021USD ($)	Dec. 31, 2020USD ($)	Dec. 01, 2020USD ($)	Mar. 31, 2021USD ($)	Mar. 31, 2020USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Subsequent Event [Line Items]
Operating lease expiring date								Jan. 31, 2023
Monthly base rent						$ 700,000	$ 640,000	$ 2,552,000	$ 2,568,000
Proceeds from common stock						$ 463,825,000		99,800,000
Class A Common Stock | VGA
Subsequent Event [Line Items]
Proceeds from common stock			$ 100,000,000	$ 100,000,000	$ 100,000,000			$ 100,000,000
Subsequent Event
Subsequent Event [Line Items]
Area of rentable space lease | ft²		197,000
Operating lease expiring date		Sep. 30, 2032
Duration of abated monthly base rent		10 months
Lease term during which abated monthly base rent to be received		2 years
Subsequent Event | Class A Common Stock | VGA
Subsequent Event [Line Items]
Proceeds from common stock	$ 100,000,000
Minimum | Subsequent Event
Subsequent Event [Line Items]
Monthly base rent		$ 400,000
Maximum | Subsequent Event
Subsequent Event [Line Items]
Monthly base rent		$ 530,000

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Summary of Property and Equipment and Their Estimated Useful Lives (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Computers and Hardware
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of assets	3 years	3 years
Furniture and Fixtures
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of assets	7 years	7 years
Lab Equipment
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of assets	5 years	5 years
Building and Improvements
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of assets		25 years
Leasehold Improvements
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of assets	Shorter of the lease term (including estimated renewals) or the estimated useful lives of the improvements	Shorter of the lease term (including estimated renewals) or the estimated useful lives of the improvements

Recent Accounting Pronounceme_2

Recent Accounting Pronouncements - Additional Information (Details)	Mar. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Change in accounting principle, accounting standards update, adopted			true
Change in accounting principle, accounting standards update, adoption date			Jan. 1, 2019
ASU 2016-13
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Change in accounting principle, accounting standards update, adopted		true
Change in accounting principle, accounting standards update, adoption date		Jan. 1, 2020
Change in accounting principle, accounting standards update, immaterial effect		true
ASU 2018-18
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Change in accounting principle, accounting standards update, adopted		true
Change in accounting principle, accounting standards update, adoption date		Jan. 1, 2020
Change in accounting principle, accounting standards update, immaterial effect		true
ASU 2019-12
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Change in accounting principle, accounting standards update, adopted	true
Change in accounting principle, accounting standards update, adoption date	Mar. 31, 2021
Change in accounting principle, accounting standards update, immaterial effect	true

Restatement of Consolidated F_3

Restatement of Consolidated Financial Statements - Impact of Restatement on Consolidated Balance Sheet (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Error Corrections And Prior Period Adjustments Restatement [Line Items]
Total current assets	$ 1,541,944	$ 1,009,168		$ 131,176
Total assets	1,616,337	1,066,769		172,384
Liabilities, redeemable non-controlling interest and stockholders’ equity
Total current liabilities	21,354	12,350		7,223
Assumed common stock warrant liabilities	288,039	689,699
Total liabilities	320,737	713,293		21,982
Redeemable non-controlling interest	1,694	1,704	$ 1,706	1,710	$ 1,690
Stockholders’ equity
Preferred stock - $0.0001 par value
Common stock - $0.0001 par value	39	36		24
Additional paid-in-capital	3,346,442	2,329,406		444,440
Accumulated other comprehensive (loss) income	143	(31)		90
Accumulated deficit	(2,052,718)	(1,977,639)		(295,862)
Total stockholders’ equity	1,293,906	351,772	$ 135,843	148,692	191,230
Total liabilities, redeemable non-controlling interest and stockholders’ equity	$ 1,616,337	1,066,769		172,384
Previously Reported
Error Corrections And Prior Period Adjustments Restatement [Line Items]
Total current assets		1,009,168
Total assets		1,066,769
Liabilities, redeemable non-controlling interest and stockholders’ equity
Total current liabilities		12,350
Total liabilities		23,594
Redeemable non-controlling interest		1,704		$ 1,700	1,690
Stockholders’ equity
Preferred stock - $0.0001 par value
Common stock - $0.0001 par value		36
Additional paid-in-capital		2,437,242
Accumulated other comprehensive (loss) income		(31)
Accumulated deficit		(1,395,776)
Total stockholders’ equity		1,041,471			$ (214,345)
Total liabilities, redeemable non-controlling interest and stockholders’ equity		1,066,769
Restatement Adjustment
Liabilities, redeemable non-controlling interest and stockholders’ equity
Assumed common stock warrant liabilities		689,699
Total liabilities		689,699
Stockholders’ equity
Preferred stock - $0.0001 par value
Additional paid-in-capital		(107,836)
Accumulated deficit		(581,863)
Total stockholders’ equity		$ (689,699)

Restatement of Consolidated F_4

Restatement of Consolidated Financial Statements - Impact of Restatement on Consolidated Balance Sheet (Parenthetical) (Details) - $ / shares	Mar. 31, 2021	Dec. 31, 2020	Nov. 25, 2020	Dec. 31, 2019
Error Corrections And Prior Period Adjustments Restatement [Line Items]
Preferred stock, par value	$ 0.0001	$ 0.0001		$ 0.0001
Common stock, par value		$ 0.0001	$ 0.0001

Restatement of Consolidated F_5

Restatement of Consolidated Financial Statements - Impact of Restatement on Consolidated Statement of Operations and Comprehensive Loss (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Error Corrections And Prior Period Adjustments Restatement [Line Items]
Total operating expenses	$ 44,675	$ 15,916	$ 81,021	$ 55,818
Loss from operations	(44,675)	(15,916)	(81,021)	(55,818)
Other (loss) income:
Interest expense			(20,765)	(94)
Interest income	247	538	1,093	3,608
Change in fair value of Series F convertible preferred stock tranche liabilities			(999,987)
Change in fair value of assumed common stock warrant liabilities	(30,800)		(581,863)
Other income	103		760	1,041
Total other (loss) income	(30,414)	538	(1,600,762)	4,555
Net loss	(75,089)	(15,378)	(1,681,783)	(51,263)
Less: Net (loss) income attributable to non-controlling interest, net of tax of $0 for the years ended December 31, 2020 and 2019	(10)	(4)	(6)	20
Net loss attributable to common stockholders	(75,079)	(15,374)	(1,681,777)	(51,283)
Other comprehensive (loss) income:
Unrealized (loss) gain on marketable securities	174	315	(121)	121
Total comprehensive loss	(74,915)	(15,063)	(1,681,904)	(51,142)
Less: Comprehensive (loss) income attributable to non-controlling interest	(10)	(4)	(6)	20
Comprehensive loss attributable to common stockholders	$ (74,905)	$ (15,059)	$ (1,681,898)	$ (51,162)
Basic and Diluted net loss per share	$ (0.20)	$ (0.06)	$ (6.67)	$ (0.21)
Basic and Diluted weighted-average common shares outstanding	368,783,516	239,792,967	252,143,509	239,636,062
Previously Reported
Error Corrections And Prior Period Adjustments Restatement [Line Items]
Total operating expenses			$ 81,021
Loss from operations			(81,021)
Other (loss) income:
Interest expense			(20,765)
Interest income			1,093
Change in fair value of Series F convertible preferred stock tranche liabilities			(999,987)
Other income			760
Total other (loss) income			(1,018,899)
Net loss			(1,099,920)
Less: Net (loss) income attributable to non-controlling interest, net of tax of $0 for the years ended December 31, 2020 and 2019			(6)
Net loss attributable to common stockholders			(1,099,914)
Other comprehensive (loss) income:
Unrealized (loss) gain on marketable securities			(121)
Total comprehensive loss			(1,100,041)
Less: Comprehensive (loss) income attributable to non-controlling interest			(6)
Comprehensive loss attributable to common stockholders			$ (1,100,035)
Basic and Diluted net loss per share			$ (4.36)
Basic and Diluted weighted-average common shares outstanding			252,143,509
Restatement Adjustment
Other (loss) income:
Change in fair value of assumed common stock warrant liabilities			$ (581,863)
Total other (loss) income			(581,863)
Net loss			(581,863)
Net loss attributable to common stockholders			(581,863)
Other comprehensive (loss) income:
Total comprehensive loss			(581,863)
Comprehensive loss attributable to common stockholders			$ (581,863)

Restatement of Consolidated F_6

Restatement of Consolidated Financial Statements - Impact of Restatement on Consolidated Statement of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Error Corrections And Prior Period Adjustments Restatement [Line Items]
Net loss	$ (75,089)	$ (15,378)	$ (1,681,783)	$ (51,263)
Adjustments to reconcile net loss to net cash used in operating activities			1,620,520
Net cash used in operating activities	(21,536)	(11,481)	(61,263)	(41,731)
Net cash used in investing activities	97,839	27,066	(802,648)	33,301
Net cash provided by financing activities	$ 572,822	$ 13	953,724	$ 394
Previously Reported
Error Corrections And Prior Period Adjustments Restatement [Line Items]
Net loss			(1,099,920)
Adjustments to reconcile net loss to net cash used in operating activities			1,038,657
Net cash used in operating activities			(61,263)
Net cash used in investing activities			(802,648)
Net cash provided by financing activities			953,724
Restatement Adjustment
Error Corrections And Prior Period Adjustments Restatement [Line Items]
Net loss			(581,863)
Adjustments to reconcile net loss to net cash used in operating activities			$ 581,863

Restatement of Consolidated F_7

Restatement of Consolidated Financial Statements - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended	4 Months Ended
	Mar. 31, 2021	May 06, 2021
Error Corrections And Prior Period Adjustments Restatement [Line Items]
Net proceeds from warrant exercised	$ 109,133
Public Warrants
Error Corrections And Prior Period Adjustments Restatement [Line Items]
Net proceeds from warrant exercised	$ 109,100
Public Warrants | Forecast
Error Corrections And Prior Period Adjustments Restatement [Line Items]
Warrant exercised		9,699,528
Net proceeds from warrant exercised		$ 111,500

Business Combination - Schedule

Business Combination - Schedule of Reconciliation of Elements of Business Combination to Consolidated Statement of Cash Flows and Consolidated Statement of Redeemable Non-Controlling Interest and Stockholders' Equity (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Business Combination [Line Items]
Proceeds from issuance of Class A Common Stock pursuant to Legacy QuantumScape Series F Preferred Stock Purchase Agreement, net of issuance costs	$ 463,825	$ 99,800
Net cash contributions from Business Combination		676,863
Kensington
Business Combination [Line Items]
Proceeds from issuance of Class A Common Stock pursuant to Legacy QuantumScape Series F Preferred Stock Purchase Agreement, net of issuance costs		230,128
Cash- PIPE Financing		500,000
Non-cash net assets assumed from Kensington		592
Less: Fair value of assumed common stock warrants (Restated)		109,081
Less: transaction costs and advisory fees for QuantumScape allocated to equity (Restated)		41,664
Less: transaction costs and advisory fees for Kensington (Restated)		11,372
Net Business Combination (Restated)		568,603
Less: non-cash net assets assumed from Kensington		592
Less: transaction costs and advisory fees for QuantumScape allocated to warrants (Restated)		1,245
Add: Non-cash fair value of assumed common stock warrants (Restated)		109,081
Add: accrued transaction costs and advisor fees		1,016
Net cash contributions from Business Combination		$ 676,863

Business Combination - Schedu_2

Business Combination - Schedule of Number of Shares of Common Stock Issued Immediately Following Consummation of Business Combination (Details) - shares	Mar. 31, 2021	Dec. 31, 2020	Nov. 25, 2020	Nov. 24, 2020	Dec. 31, 2019
Business Combination [Line Items]
Common stock, outstanding			22,984,745	23,000,000
Less: redemption of Kensington shares			15,255
Common stock, issued			347,770,673
Business Combination and PIPE Financing shares - Class A common stock			78,734,745
Class A Common Stock
Business Combination [Line Items]
Common stock, outstanding	233,610,488	207,769,091			81,720,530
Common stock, issued	233,610,488	207,769,091			81,720,530
Class B Common Stock
Business Combination [Line Items]
Common stock, outstanding	156,161,849	156,224,614			158,056,527
Common stock, issued	156,161,849	156,224,614			158,056,527
PIPE Financing
Business Combination [Line Items]
Common stock, issued			50,000,000
Legacy Quantum Scape | Class A Common Stock
Business Combination [Line Items]
Common stock, outstanding				27,533,913
Common stock, issued			110,734,478
Legacy Quantum Scape | Class B Common Stock
Business Combination [Line Items]
Common stock, outstanding				39,361,342
Common stock, issued			158,301,450
Founder Shares | Kensington
Business Combination [Line Items]
Common stock, issued			5,750,000

Business Combination - Schedu_3

Business Combination - Schedule of Number of Shares of Common Stock Issued Immediately Following Consummation of Business Combination (Parenthetical) (Details) - shares	Mar. 31, 2021	Dec. 31, 2020	Nov. 25, 2020	Nov. 24, 2020	Dec. 31, 2019
Business Combination [Line Items]
Common stock, outstanding			22,984,745	23,000,000
Class A Common Stock
Business Combination [Line Items]
Common stock, outstanding	233,610,488	207,769,091			81,720,530
Class B Common Stock
Business Combination [Line Items]
Common stock, outstanding	156,161,849	156,224,614			158,056,527
Legacy Quantum Scape | Class A Common Stock
Business Combination [Line Items]
Common stock, outstanding				27,533,913
Legacy Quantum Scape | Class B Common Stock
Business Combination [Line Items]
Common stock, outstanding				39,361,342

Fair Value Measurement - Summ_3

Fair Value Measurement - Summary of Financial Assets and Liabilities Subject to Fair Value Measurements on Recurring Basis (Details) - Recurring - USD ($) $ in Thousands		Mar. 31, 2021		Dec. 31, 2020		Dec. 31, 2019
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value assets		$ 1,526,926		$ 989,561		$ 125,762
Total fair value Liabilities		288,039		689,699		1,860
Assumed Public Common Stock Warrants
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value Liabilities		66,860		436,999
Assumed Private Placement Common Stock Warrants
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value Liabilities		221,179		252,700
Convertible Preferred Stock Warrant Liabilities
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value Liabilities						1,860
Money Market Fund
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value assets	[1]	755,825		12,235		5,163
Marketable Securities
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value assets		771,101	[2]	977,326	[3]	120,599	[4]
Level 1
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value assets		755,825		12,235		5,163
Total fair value Liabilities		66,860		436,999
Level 1 | Assumed Public Common Stock Warrants
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value Liabilities		66,860		436,999
Level 1 | Money Market Fund
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value assets	[1]	755,825		12,235		5,163
Level 2
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value assets		771,101		977,326		120,599
Total fair value Liabilities		221,179		252,700
Level 2 | Assumed Private Placement Common Stock Warrants
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value Liabilities		221,179		252,700
Level 2 | Marketable Securities
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value assets		$ 771,101	[2]	$ 977,326	[3]	120,599	[4]
Level 3
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value Liabilities						1,860
Level 3 | Convertible Preferred Stock Warrant Liabilities
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total fair value Liabilities						$ 1,860
[1]	Money market funds are included in Cash and cash equivalents on the Consolidated Balance Sheet.
[2]	As of December 31, 2020, marketable securities with original maturities of three months or less of $105.2 million, are included in cash and cash equivalents on the Condensed Consolidated Balance Sheet. As of March 31, 2021, there were no marketable securities with original maturities of three months or less included in cash and cash equivalents on the Condensed Consolidated Balance Sheet
[3]	Marketable securities with original maturities of three months or less, in the amount of $105.2 million and $18.7 million, are included in Cash and cash equivalents on the Consolidated Balance Sheet as of December 31, 2020 and December 31, 2019, respectively As of December 31, 2020, marketable securities with original maturities of three months or less of $105.2 million, are included in cash and cash equivalents on the Condensed Consolidated Balance Sheet. As of March 31, 2021, there were no marketable securities with original maturities of three months or less included in cash and cash equivalents on the Condensed Consolidated Balance Sheet
[4]	Marketable securities with original maturities of three months or less, in the amount of $105.2 million and $18.7 million, are included in Cash and cash equivalents on the Consolidated Balance Sheet as of December 31, 2020 and December 31, 2019, respectively

Fair Value Measurement - Summ_4

Fair Value Measurement - Summary of Major Security Type Assets That Measured at Fair Value on Recurring Basis (Details) - Recurring - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Schedule of Available for Sale Securities [Line Items]
Amortized Cost	$ 1,526,783	$ 989,592	$ 125,672
Unrealized Gain	143	24	90
Unrealized Loss		(55)
Fair Value	1,526,926	989,561	125,762
Level 1 | Money Market Fund
Schedule of Available for Sale Securities [Line Items]
Amortized Cost	755,825	12,235	5,163
Fair Value	755,825	12,235	5,163
Level 2
Schedule of Available for Sale Securities [Line Items]
Amortized Cost			120,509
Unrealized Gain			90
Fair Value			120,599
Level 2 | US Government Securities
Schedule of Available for Sale Securities [Line Items]
Amortized Cost	770,958	977,357	107,009
Unrealized Gain	143	24	90
Unrealized Loss		(55)
Fair Value	$ 771,101	$ 977,326	107,099
Level 2 | Repurchase Agreement
Schedule of Available for Sale Securities [Line Items]
Amortized Cost			13,500
Fair Value			$ 13,500

Fair Value Measurement - Additi

Fair Value Measurement - Additional Information (Details)

Mar. 31, 2021USD ($)shares

Dec. 01, 2020USD ($)shares

Sep. 30, 2020USD ($)Tranche$ / sharesshares

Aug. 31, 2020USD ($)$ / sharesshares

May 31, 2020USD ($)Tranche$ / sharesshares

Jan. 31, 2015$ / sharesshares

Mar. 31, 2021Securityshares

Mar. 31, 2020USD ($)

Dec. 31, 2020USD ($)Security$ / sharesshares

Dec. 31, 2019USD ($)shares

Dec. 31, 2013$ / sharesshares

Nov. 25, 2020$ / shares

Class of Stock [Line Items]

Number of marketable securities | Security

0

12

Number of positions continuous unrealized loss for more than twelve months | Security

0

Aggregate fair value of marketable securities in unrealized loss position | $

$ 419,200,000

$ 0

Allowance for credit losses | $

$ 0

$ 0

Preferred stock, shares issued

0

0

0

0

Series F Convertible Preferred Stock

Class of Stock [Line Items]

Warrants exercise price per share | $ / shares

$ 26.4218

$ 26.4218

$ 26.4218

$ 26.42

Proceeds from issuance of convertible preferred stock | $

$ 200,000,000

$ 188,000,000

$ 200,000,000

Preferred stock, shares issued

7,569,508

7,115,335

7,569,508

Number of funded tranches | Tranche

2

2

Adjusted exchange ratio of warrants | $ / shares

$ 23.50

TPC1 Warrants | Series A Convertible Preferred Stock

Class of Stock [Line Items]

Warrants issued to purchase of convertible preferred stock

124,586

Convertible preferred stock price per share | $ / shares

$ 2.20131

Warrants set to expire from effective date

7 years

TPC1 Warrants | Series C Convertible Preferred Stock

Class of Stock [Line Items]

Warrants issued to purchase of convertible preferred stock

129,718

Convertible preferred stock price per share | $ / shares

$ 10.40717

Warrants expiration period

expire at the later of 2022 or five years after an initial public offering or acquisition.

TPC1 Warrants | Class A Common Stock

Class of Stock [Line Items]

Warrants to purchase shares of common stock

501,047

Warrants exercise price per share | $ / shares

$ 0.5473

Triple Point Capital Two Warrants | Series C Convertible Preferred Stock

Class of Stock [Line Items]

Warrants issued to purchase of convertible preferred stock

129,718

Convertible preferred stock price per share | $ / shares

$ 10.40717

Warrants expiration period

expire at the later of 2022 or five years after an initial public offering or acquisition.

Triple Point Capital Two Warrants | Class A Common Stock

Class of Stock [Line Items]

Warrants to purchase shares of common stock

998,460

Warrants exercise price per share | $ / shares

$ 2.5877

Fair value of warrant | $

$ 0

Triple Point Capital Two Warrants | Class A Common Stock | Scenario Previously Reported [Member]

Class of Stock [Line Items]

Warrants to purchase shares of common stock

521,693

TPC1 And TPC 2 Warrants | Class A Common Stock

Class of Stock [Line Items]

Warrants to purchase shares of common stock

998,460

Fair value of warrant | $

$ 22,600,000

Tranche One | Series F Convertible Preferred Stock

Class of Stock [Line Items]

Proceeds from issuance of convertible preferred stock | $

$ 100,000,000

Preferred stock, shares issued

3,784,754

Tranche Two | Series F Convertible Preferred Stock | Forecast

Class of Stock [Line Items]

Proceeds from issuance of convertible preferred stock | $

$ 100,000,000

Preferred stock, shares issued

3,784,754

3,784,754

Tranche Three | Series F Convertible Preferred Stock

Class of Stock [Line Items]

Proceeds from issuance of convertible preferred stock | $

$ 94,000,000

Tranche Four | Series F Convertible Preferred Stock

Class of Stock [Line Items]

Proceeds from issuance of convertible preferred stock | $

$ 94,000,000

Fair Value Measurement - Summ_5

Fair Value Measurement - Summary of Fair Value of Warrants Re-measured Using OPM (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Option term (in years)	6 years 29 days	6 years 7 days
Volatility	70.00%	70.00%
Risk-free interest rate	0.39%	1.92%
TPC1 Warrants
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Option term (in years)	5 years	5 years
Volatility	70.00%	58.50%
Risk-free interest rate	0.39%	1.69%
Discount for lack of marketability		35.00%
Triple Point Capital Two Warrants
Fair Value Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Option term (in years)	5 years	5 years
Volatility	70.00%	45.00%
Risk-free interest rate	0.39%	1.69%
Discount for lack of marketability		35.00%

Fair Value Measurement - Schedu

Fair Value Measurement - Schedule of Reconciliation of Warrants and Tranche Liabilities Measured and Recorded at Fair Value on Recurring Basis Using Significant Unobservable Inputs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Fair Value Liabilities Measured on Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning balance	$ 1,860	$ 1,766
Re-measurement loss included in interest expense	20,765	94
Reclassification to additional paid-in capital upon recapitalization	(22,625)
Ending balance		1,860
Series F Convertible Preferred Stock
Fair Value Liabilities Measured on Recurring Basis Unobservable Input Reconciliation [Line Items]
Re-measurement loss included in interest expense	999,865
Issuance of Legacy QuantumScape Series F Preferred Stock - tranche shares 3 and 4	(484,471)
Reclassification to additional paid-in capital upon Closing of the Business Combination - tranche shares 1 and 2	(515,394)
TPC1 Warrants
Fair Value Liabilities Measured on Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning balance	1,036	984
Re-measurement loss included in interest expense	10,475	52
Reclassification to additional paid-in capital upon recapitalization	(11,511)
Ending balance		1,036
Triple Point Capital Two Warrants
Fair Value Liabilities Measured on Recurring Basis Unobservable Input Reconciliation [Line Items]
Beginning balance	824	782
Re-measurement loss included in interest expense	10,290	42
Reclassification to additional paid-in capital upon recapitalization	$ (11,114)
Ending balance		$ 824

Leases - Additional Information

Leases - Additional Information (Details)	1 Months Ended	3 Months Ended	12 Months Ended
	May 31, 2017ft²	Mar. 31, 2021USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Mar. 31, 2018ft²
Lessee Lease Description [Line Items]
Operating lease expiring date			Jan. 31, 2023
Operating lease, renewal term		60 months	60 months
Financing leases | $		$ 0	$ 0	$ 0
Area of sublease | ft²	15,000
Sublease term	3 years
Area of sublease amended to add sublease agreement | ft²					11,000
Operating lease expiration, month and year		2028-01
Change in accounting principle, accounting standards update, adopted				true
Change in accounting principle, accounting standards update, adoption date				Jan. 1, 2019
Accounting Standards Update [Extensible List]				us-gaap:AccountingStandardsUpdate201602Member
Other Income (Expense)
Lessee Lease Description [Line Items]
Sublease income | $				$ 900,000

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details)	Feb. 26, 2021shares	Feb. 28, 2021SuitOfficer_Director	Feb. 08, 2021Officer_Director
Commitments And Contingencies [Line Items]
Number of officers and directors in shareholder derivative suit		11
Number of shareholder derivative suit filed | Suit		2
Number of shares sought in arbitration demand | shares	804,350
Subsequent Event
Commitments And Contingencies [Line Items]
Number of officers and directors in shareholder derivative suit			11

Assumed Common Stock Warrants -

Assumed Common Stock Warrants - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	Feb. 13, 2021	Feb. 12, 2021	Feb. 12, 2021	Mar. 31, 2021	Dec. 31, 2020
Class Of Warrant Or Right [Line Items]
Warrants outstanding				8,660,225	18,149,989
Non-cash change in fair value of assumed common stock warrant liabilities				$ 30,800	$ 581,863
Net proceeds from warrant exercises				$ 109,133
Private Placement and Working Capital Warrants Redemption Starting July 30, 2021
Class Of Warrant Or Right [Line Items]
Warrants redemption price per share					$ 0.01
Number of trading days				20 days	20 days
Number of trading days ending on third business day					30 days
Minimum share price required for redemption of warrants					$ 18
Warrants redemption price per share				$ 0.01
Number of trading days ending on third business day				30 days
Minimum share price required for redemption of warrants				$ 18
Private Placement and Working Capital Warrants
Class Of Warrant Or Right [Line Items]
Warrants sold				6,575,000	6,575,000
Warrants exercise price per share				$ 11.50	$ 11.50
Warrant issued in connection with the closing of business combination				75,000	75,000
Private Placement and Working Capital Warrants Commencing September 28, 2021
Class Of Warrant Or Right [Line Items]
Warrants redemption price per share					$ 0.10
Number of trading days				30 days
Number of days after written notice of redemption				30 days	30 days
Private Placement and Working Capital Warrants Commencing September 28, 2021 | Minimum
Class Of Warrant Or Right [Line Items]
Number of trading days					30 days
Warrants redemption price per share				$ 0.10
Public Warrants
Class Of Warrant Or Right [Line Items]
Warrants outstanding				2,010,225	11,499,989
Warrants sold				11,499,989
Warrants exercise price per share				$ 11.50	$ 11.50
Public warrants exercisable date	Mar. 5, 2021	Jun. 30, 2021
Warrant exercisable number of shares	1			1
Share price	$ 11.50
Warrants exercised				9,489,764
Net proceeds from warrant exercises				$ 109,100
Public Warrants | Subsequent Event
Class Of Warrant Or Right [Line Items]
Public warrants exercisable date	Mar. 5, 2021		Jun. 30, 2021
Warrant exercisable number of shares	1
Share price	$ 11.50
Public Warrants
Class Of Warrant Or Right [Line Items]
Warrants sold				11,499,989	11,499,989
Warrants exercise price per share				$ 11.50	$ 11.50

Stockholders' Equity - Schedu_2

Stockholders' Equity - Schedule of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Outstanding at the beginning of the period (in shares)	55,316,336	55,456,890	55,456,890	44,691,300
Conversion of awards due to recapitalization (in shares)				33,578,834
Granted (in shares)	0	0	3,866,992	11,955,658
Cancelled and forfeited (in shares)	(366,724)		(3,361,530)	(571,664)
Exercised (in shares)	(2,884,549)		(646,016)	(618,404)
Outstanding at the end of the period (in shares)	52,065,063		55,316,336	55,456,890	44,691,300
Vested and exercisable at the end of the period (in shares)	41,102,851		41,944,514
Outstanding at the beginning of the period (in dollars per share)	$ 1.62	$ 1.32	$ 1.32	$ 1.03
Conversion of awards due to recapitalization (in dollars per share)				(3.12)
Granted (in dollars per share)			5.08	2.38
Cancelled and forfeited (in dollars per share)	2.34		0.85	1.43
Exercised (in dollars per share)	0.30		0.93	0.64
Outstanding at the end of the period (in dollars per share)	1.69		1.62	$ 1.32	$ 1.03
Vested and exercisable (in dollars per share)	$ 1.26		$ 1.17
Weighted Average Remaining Contractual Term (Years)	5 years 9 months 7 days		5 years 9 months 7 days	6 years 3 months 26 days	6 years 5 months 9 days
Weighted Average Remaining Contractual Term, Vested and exercisable (in years)	5 years 14 days		4 years 10 months 17 days
Balance at end of period	$ 2,242,170		$ 4,582,001
Vested and exercisable at end of period	$ 1,787,418		$ 3,493,198
Previously Reported
Class of Stock [Line Items]
Outstanding at the beginning of the period (in shares)				11,112,466
Outstanding at the end of the period (in shares)					11,112,466
Outstanding at the beginning of the period (in dollars per share)				$ 4.15
Outstanding at the end of the period (in dollars per share)					$ 4.15

Stockholders' Equity - Schedu_3

Stockholders' Equity - Schedule of Weighted Average Assumptions Used Inputs to Black-Scholes OPM (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Volatility	70.00%	70.00%
Risk-free interest rate	0.39%	1.92%
Option term (in years)	6 years 29 days	6 years 7 days
Weighted average fair value at grant date	$ 2.67	$ 1.50

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax [Line Items]
Income tax expense (benefit)	$ 0	$ 0	$ 0	$ 0
Current income tax expense (benefit)	0	0	0	0
Deferred income tax expense (benefit)	$ 0	$ 0	$ 0	$ 0
Federal Statutory rate			21.00%	21.00%
Valuation allowance increase, amount			$ 20,104,000	$ 14,337,000
Ownership change description			The Company performed the analysis and determined that it has experienced an ownership change in December 2010 and in August 2012 as a result of the preferred stock financing rounds.
Tax credit carryforward expiration beginning year			2031
Tax credit carryforward, description			The state tax credit carryforwards do not expire.
Unrecognized tax benefits			$ 6,575,000	7,076,000	$ 5,372,000
Interest or penalties related to unrecognized tax benefits.			$ 0	$ 0
Income tax examination, description			The federal and state income tax returns are open under the statute of limitations subject to tax examinations for the tax years ended December 31, 2017 through December 31, 2019 and December 31, 2016 through December 31, 2019, respectively.
Employee retention credit			$ 900,000
Research Tax Credit Carryforward | California Franchise Tax Board
Income Tax [Line Items]
Research and development credits			$ 11,300,000
Prior to 2018
Income Tax [Line Items]
Operating loss carryforwards, expire beginning date			2030
Federal
Income Tax [Line Items]
Operating loss carryforwards			$ 340,700,000
Operating loss carryforwards, indefinite			170,400,000
Federal | Research Tax Credit Carryforward
Income Tax [Line Items]
Research and development credits			13,400,000
Federal | Prior to 2018
Income Tax [Line Items]
Operating loss carryforwards			170,300,000
State
Income Tax [Line Items]
Operating loss carryforwards			231,200,000
State | Expire Beginning in 2030, If Not Utilized
Income Tax [Line Items]
Operating loss carryforwards			$ 231,200,000

Income Taxes - Schedule of Reco

Income Taxes - Schedule of Reconciliation of Effective Income Tax Rate (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Federal Statutory rate	21.00%	21.00%
State tax expense	0.00%	7.00%
Permanent tax items	(0.20%)	(2.20%)
R&D tax credit	0.20%	4.50%
Other	(0.10%)	0.00%
Change to valuation allowance	(1.10%)	(30.40%)
Change in fair value of assumed common stock warrant liabilities	(7.30%)	0.00%
Change in fair value of Series F tranche liabilities	(12.50%)	0.00%
Effective tax rate	0.00%	0.00%

Income Taxes - Components of Ne

Income Taxes - Components of Net Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets:
Net operating losses	$ 88,392	$ 71,374
Tax credits	16,314	10,219
Accruals and stock-based compensation	3,313	4,671
Lease liability	2,621	3,796
Intangibles	1,413	90
Gross deferred tax assets	112,053	90,150
Valuation allowance	(105,781)	(85,677)	$ (71,340)
Total deferred tax assets	6,272	4,473
Deferred tax liabilities:
Right of use assets	(2,463)	(3,627)
Fixed assets	(3,809)	(846)
Total deferred tax liabilities	$ (6,272)	$ (4,473)

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Beginning and Ending Balances of Valuation Allowance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Beginning of the year	$ (85,677)	$ (71,340)
Increase	(20,104)	(14,337)
End of the year	$ (105,781)	$ (85,677)

Income Taxes - Reconciliation_2

Income Taxes - Reconciliation of Beginning and Ending Balances of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Beginning of the year	$ 7,076	$ 5,372
Increase—current year positions	1,553	1,704
Increase—prior year positions	193
Decrease—prior year positions	(2,247)
End of the year	$ 6,575	$ 7,076