X0206 3 2021-10-08 0 0001819438 ESS Tech, Inc. GWH 0001885331 Evans Craig E C/O ESS TECH, INC. 26440 SW PARKWAY AVE., BLDG. 83 WILSONVILLE OR 97070 1 1 0 0 President 0001884681 Song Julia C/O ESS TECH, INC. 26440 SW PARKWAY AVE., BLDG. 83 WILSONVILLE OR 97070 0 1 0 0 Chief Technology Officer Common Stock 4602453 D Common Stock 1917211 I See footnote Employee Stock Option (right to buy) 0.3331 2030-07-23 Common Stock 172395 D Employee Stock Option (right to buy) 0.3061 2028-04-19 Common Stock 38923 I See footnote Employee Stock Option (right to buy) 0.3305 2030-07-23 Common Stock 296058 I See footnote Restricted Stock Units 2026-04-08 Common Stock 58984 D Restricted Stock Units 2026-04-08 Common Stock 56626 I See footnote Pursuant to an "earnout" provision of the Agreement and Plan of Merger, dated as of May 6, 2021 (the "Merger Agreement"), by and among ACON S2 Acquisition Corp, SCharge Merger Sub, Inc., and ESS Tech, Inc., the reporting person is entitled to receive additional shares of common stock, for no additional consideration, if the volume weighted average price of the common stock over twenty trading days within any thirty trading day period exceeds certain thresholds (the "Earnout Rights"). Of these Earnout Rights, one half will be issued if the volume weighted average price of the common stock over twenty trading days within any thirty trading day period is greater than or equal to $12.50, and one half will be issued if the volume weighted average price of the common stock over twenty trading days within any thirty trading day period is greater than or equal to $15.00. The shares are held Julia Song. The reporting persons are husband and wife. The shares subject to the option vest in 48 equal monthly installments beginning on February 22, 2021. The shares subject to the option are fully vested and immediately exercisable. The shares subject to the option vest in 48 equal monthly installments beginning on August 24, 2020. Each restricted stock unit, or RSU, represents a contingent right to receive one share of common stock. The RSUs vest if the common stock exceeds the same thresholds as the Earnout Rights described in footnote (1). Exhibit 24.1 - Power of Attorney - Craig Evans Exhibit 24.2 - Power of Attorney - Julia Song /s/ Amir Moftakhar, by power of attorney for Craig Evans 2021-10-18 /s/ Amir Moftakhar, by power of attorney for Julia Song 2021-10-18