Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Cash flows from operating activities:
Net loss	$ (5,709)	$ (154,918)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	196	130
Non-cash interest expense	14	21
Non-cash lease expense	275	0
Stock-based compensation expense	2,760	129
Change in fair value of warrant liabilities	(15,664)	8,426
Loss on revaluation of derivative liabilities	0	138,141
Change in earnout liabilities	(840)	0
Changes in operating assets and liabilities:
Accounts receivable	785	0
Prepaid expenses and other assets	405	(294)
Prepaid expenses and other assets	(1,596)	1,882
Net cash used in operating activities	(19,374)	(6,483)
Cash flows from investing activities:
Purchases of property and equipment	(4,041)	(133)
Net cash used in investing activities	(4,041)	(133)
Cash flows from financing activities:
Principal payments on notes payable	(483)	(101)
Proceeds from stock options exercised	47	518
Repurchase of shares from employees for income tax withholding purposes	(2,808)	0
Proceeds from sale of Legacy ESS Series C-2 redeemable convertible preferred stock, net of issuance costs	0	11,461
Net cash (used in) provided by financing activities	(3,244)	11,878
Net change in cash, cash equivalents and restricted cash	(26,659)	5,262
Cash, cash equivalents and restricted cash, beginning of period	240,232	6,394
Cash, cash equivalents and restricted cash, end of period	213,573	11,656
Supplemental disclosures of cash flow information:
Cash paid for operating leases included in cash used in operating activities	403	0
Non-cash investing and financing transactions:
Purchase of property and equipment included in accounts payable and accrued and other current liabilities	2,235	22
Right-of-use operating lease assets obtained in exchange for lease obligations	4,534	0
Right-of-use finance lease assets obtained in exchange for lease obligations	123	0
Extinguishment of derivative liabilities upon sale of Legacy ESS Series C-2 redeemable convertible preferred stock, net of amount allocated to warrants	0	18,055
Extinguishment of warrant liabilities upon exercise of Legacy ESS Series B, Series C-1 and Series C-2 redeemable convertible preferred stock warrants	0	356
Cash and cash equivalents	212,331	10,163
Restricted cash, current	1,167	1,167
Restricted cash, non-current	75	326
Total cash, cash equivalents and restricted cash shown in the statements of cash flows	$ 213,573	$ 11,656