Annual report pursuant to Section 13 and 15(d)

Consolidated Statements of Cash Flows

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net loss	$ (40,254)	$ (26,580)	$ (13,557)
Reconciliation of net loss to net cash used in operating activities
Depreciation	3,213	2,908	687
Amortization of intellectual property	190	163	128
Accretion of asset retirement obligation	44	31	0
Fair value of warrant modification, net	402	0	0
Fair value of warrants issued for consulting services	0	0	138
Fair value of common stock issued for consulting services	423	0	0
Stock-based compensation	1,201	1,081	1,060
Amortization of debt discount	2,006	360	54
Amortization of deferred financing costs	83	83	62
Non-cash convertible note interest expense	690	618	343
Lease liability, net of deferred rent write-off	(493)	0	0
Amortization of lease liability	(80)	0	0
Impairment of acquired intellectual property	0	2,411	0
Loss on sale of equipment	869	76	0
Inventory write down	179	456	0
Changes in operating assets and liabilities
Accounts receivable	157	(882)	0
Inventory	295	(1,636)	(59)
Prepaid expenses and other current assets	400	236	(394)
Accounts payable	472	926	(176)
Accrued expenses	4,009	924	564
Deferred rent	(124)	(177)	29
Net cash used in operating activities	(26,318)	(19,002)	(11,121)
Cash flows from investing activities:
Purchases of property and equipment	(3,693)	(8,819)	(29,156)
Proceeds from sale of equipment	0	4	0
Other assets	(236)	(345)	(250)
Intellectual property related expenditures	0	(615)	(200)
Net cash used in investing activities	(3,929)	(9,775)	(29,606)
Cash flows from financing activities:
Proceeds from issuance of common stock, net of transaction costs	28,753	25,325	30,709
Payments on notes payable	(277)	(201)	(14)
Payments on capital leases	(130)	(136)	(52)
Proceeds from issuance of convertible notes payable, net of issuance costs	0	0	4,858
Net cash provided by financing activities	28,346	24,988	35,501
Net decrease in cash, cash equivalents and restricted cash	(1,901)	(3,789)	(5,226)
Cash, cash equivalents and restricted cash at beginning of period	22,793	26,582	31,808
Cash, cash equivalents and restricted cash at end of period	20,892	22,793	26,582
Supplemental disclosure of cash flow information:
Cash paid for interest, net of amounts capitalized	668	699	330
Cash paid for income taxes	2	2	1
Non-cash investing activities
Tenant improvement allowances	0	0	78
Non-cash financing activities
Capital lease	38	0	310
Fair value of consulting warrants	0	0	138
Fair value of financing warrants	0	0	229
Fair value of common stock issued to consultants	423	0	0
Total non-cash financing activities	461	0	677
Supplemental disclosure of non-cash transactions
Change in property and equipment resulting from change in accounts payable	180	(1,062)	1,200
Change in property and equipment resulting from change in accrued expenses	(14)	(1,098)	1,330
Recognition of convertible debt discount	0	0	4,975
Asset retirement obligation offset with asset retirement cost (property and equipment)	0	670	0
Fair value of common stock issued for intellectual property	0	2,149	0
Reduction in accrued liabilities upon modification of Interstate Battery warrant 1	$ 600	$ 0	$ 0