Exhibit 99

JOINT FILING AGREEMENT

In accordance with Rule 13d-1(k)(1) promulgated under the Securities Exchange Act of 1934, as amended, the undersigned hereby agree to the joint filing with each other on behalf of each of them of such a statement on Schedule 13G and any amendment thereto with respect to the common stock beneficially owned by each of them of Solid Power, Inc. This Joint Filing Agreement shall be included as an Exhibit to such Schedule 13G or any amendment thereto.

IN WITNESS WHEREOF, the undersigned hereby execute this Joint Filing Agreement as of the 14^th day of February, 2022.

DECARBONIZATION PLUS ACQUISITION SPONSOR III LLC
By:	/s/ Peter Haskopoulos
Name:	Peter Haskopoulos
Title:	Authorized Person
RIVERSTONE HOLDINGS LLC
By:	/s/ Peter Haskopoulos
Name:	Peter Haskopoulos
Title:	Authorized Person
/s/ Peter Haskopoulos, attorney-in-fact
David M. Leuschen
/s/ Peter Haskopoulos, attorney-in-fact
Pierre F. Lapeyre, Jr.