Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies (Tables)

Summary of Significant Accounting Policies (Tables)

6 Months Ended

Jun. 30, 2019

Schedule of computation of potentially dilutive securities

The following shares underlying outstanding convertible notes, stock options, RSUs and warrants to purchase common stock were antidilutive due to a net loss in the periods presented and, therefore, were excluded from the dilutive securities computation for the six months ended June 30, as indicated below.



	June 30,
Excluded potentially dilutive securities (1):	2019	2018

Convertible note - principal	—	702,247
Options to purchase common stock	3,604,001	1,583,354
Unvested restricted stock units	242,023	212,100
Financing warrants to purchase common stock	4,839,197	2,340,828
Total potential dilutive securities	8,685,221	4,838,529


(1)	The number of shares is based on the maximum number of shares issuable on exercise or conversion of the related securities as of the period end. Such amounts have not been adjusted for the treasury stock method or weighted average outstanding calculations as required if the securities were dilutive.

Schedule of concentration of credit risk

Revenues from the following customers each represented at least 10% of total revenue for the three and six months ended June 30, 2019 and 2018, respectively. They also represented a significant portion of our accounts receivable as of June 30, 2019 and December 31, 2018, respectively.



	Revenue				Revenue				Accounts Receivable
	Three months ended June 30,				Six months ended June 30,				June 30, 2019		December 31, 2018
	2019		2018		2019		2018		June 30, 2019		December 31, 2018

Clarios (successor of Johnson Controls Battery Group, Inc.)	59	%	91	%	59	%	81	%	71	%	95	%
Ocean Partners USA, Inc.	—	%	5	%	—	%	15	%	—	%	—	%
P. Kay Metals	38	%	—	%	38	%	—	%	27	%	—	%