Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies (Tables)

Summary of Significant Accounting Policies (Tables)
3 Months Ended
Mar. 31, 2020
Accounting Policies [Abstract]  
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 three months ended March 31, as indicated below.
  March 31,
Excluded potentially dilutive securities (1): 2020 2019
Options to purchase common stock 1,709,106    3,440,437   
Unvested restricted stock units 2,397,299    244,785   
Financing warrants to purchase common stock 805,747    2,444,328   
Total potential dilutive securities 4,912,152    6,129,550   
(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 months ended March 31, 2020 and March 31, 2019, respectively. They also represented a significant portion of our trade accounts receivable as of December 31, 2019. The Company did not have a trade accounts receivable balance as of March 31, 2020.
Revenue Trade Accounts Receivable
Three months ended March 31, March 31, 2020 December 31, 2019
2020 2019
Clarios (successor of Johnson Controls Battery Group, Inc.) 100  % 60  % —    100  %
P. Kay Metals —    37  % —    —