X0508 4 2024-12-16 0 0001844862 Solid Power, Inc. SLDP 0001880162 Buettner-Garrett Joshua C/O SOLID POWER, INC. 486 S PIERCE AVE., SUITE E LOUISVILLE CO 80027 0 1 0 0 Chief Technology Officer 1 Common Stock 2024-12-16 4 M 0 187500 0.03 A 1057220 D Common Stock 2024-12-16 4 S 0 187500 1.0742 D 869720 D Stock Option (Right to Buy) 0.03 2024-12-16 4 M 0 187500 0 D 2021-12-08 2025-03-20 Common Stock 187500 562500 D The transactions reported on this Form 4 were made pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on September 1, 2023 (the "10b5-1 Plan") for a stock option award set to expire on March 20, 2025. The 10b5-1 Plan is structured to include several sale periods and was established to cover the reporting person's tax liability arising from the option exercises and for longer-term asset diversification. This sale was made pursuant to the 10b5-1 Plan. This transaction was executed in multiple trades at prices ranging from $1.05 to $1.098. The price reported above reflects the weighted average price. The reporting person hereby undertakes to provide upon request to the SEC staff, the issuer, or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected. /s/ James Liebscher, attorney-in-fact on behalf of Joshua Buettner-Garrett 2024-12-17