X0202 SCHEDULE 13D/A 0000929638-21-001471 0001899229 XXXXXXXX LIVE 1 Common Stock, par value $0.0001 per share 04/20/2026 false 0001844862 83422N105 Solid Power, Inc.

486 S. PIERCE AVE. SUITE E, LOUISVILLE CO 80027

Glenn Ramcharan 31-70-4133-294 Financial Director, BMW Holding B.V. Einsteinlaan 5 Rijswijk P7 2289 CC 0001899229 BMW Holding B.V. WC P7 0 10488518 0 10488518 10488518 N 4.7 OO Y BMW INTEC Beteiligungs GmbH AF 2M 0 10488518 0 10488518 10488518 N 4.7 HC OO Y Bayerische Motoren Werke AG AF 2M 0 10488518 0 10488518 10488518 N 4.7 CO HC Common Stock, par value $0.0001 per share Solid Power, Inc. 486 S. PIERCE AVE. SUITE E, LOUISVILLE CO 80027 Item 4 is hereby amended and supplemented as follows (capitalized terms have the meanings ascribed to them in the Schedule 13D filed by the Reporting Persons on December 20, 2021): As announced in the Company's Current Report on Form 8-K, as filed with the Securities and Exchange Commission on April 24, 2026, on April 20, 2026 Rainer Feurer, an executive within BMW Group, provided notice to the Company of his intention to retire from the Board of Directors effective June 30, 2026. Dr. Feurer's decision to retire and step down from the Board of Directors was not the result of any disagreement on matters relating to the Company's operations, policies or practices. BMW Holding continues to retain its director nomination rights. Based on information in the Company's Current Report on Form 8-K, as filed with the Securities and Exchange Commission on January 29, 2026, the Reporting Persons ceased to beneficially own more than 5% of the Common Stock on or about January 29, 2026. Exhibit 99.1 Joint Filing Agreement and Power of Attorney, by and among the Reporting Persons, incorporated by reference to Exhibit 99.1 to the Schedule 13D filed by the Reporting Persons on December 20, 2021 Exhibit 99.2 Board Nomination and Support Agreement dated as of May 5, 2021, by and between Solid Power, Inc., BMW Holding B.V., and those certain stockholders listed on Schedule A thereto (incorporated by reference from Exhibit 4.4 to the Registration Statement on Form S-4 (Registration No. 333-258681) of Solid Power, Inc. (f.k.a, Decarbonization Plus Acquisition Corporation III), previously filed as Exhibit 99.2 to the Schedule 13D filed by the Reporting Persons on December 20, 2021. BMW Holding B.V. /s/ Ralf Edelmann 06/01/2026 /s/ Glenn Ramcharan 06/01/2026 BMW INTEC Beteiligungs GmbH /s/ Jonathan Townend 06/02/2026 ppa. /s/ Dr. Cedrik Thiele 06/08/2026 Bayerische Motoren Werke AG ppa. /s/ Fredrik Altmann 06/01/2026 i.V. /s/ Sascha Ostermann 06/01/2026