Sec Form 4 Filing - STEPHENS JOHN JOSEPH @ Decarbonization Plus Acquisition Corp III - 2021-12-08

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person STEPHENS JOHN JOSEPH 2. Issuer Name and Ticker or Trading Symbol Decarbonization Plus Acquisition Corp III [ SLDP] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director _____ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O SOLID POWER, INC., 486 S. PIERCE AVE., SUITE E 3. Date of Earliest Transaction (MM/DD/YY) 12/08/2021 (Street) LOUISVILLE, CO80027 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Stock Option (Right to Buy) $ 5.92 12/08/2021 A 381,837 ( 1 ) 10/27/2031 Common Stock 381,837( 2 ) ( 2 ) 381,837 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other STEPHENS JOHN JOSEPH C/O SOLID POWER, INC. 486 S. PIERCE AVE., SUITE E LOUISVILLE, CO80027 X Signatures /s/ James Liebscher, attorney-in-fact on behalf of John Stephens 12/08/2021 Signature of Reporting Person Date

Explanation of Responses:

( 1 )1/3 of the total number of shares issuable upon exercise of the option will vest on each of September 29, 2022, September 29, 2023, and September 29, 2024. ( 2 )On December 8, 2021, the Issuer completed the merger (the "Merger") pursuant to the as amended Business Combination Agreement and Plan of Reorganization, by and among the Issuer, a wholly owned subsidiary of the Issuer, and Solid Power, Inc. ("Solid Power"). At the effective time of the Merger (the "Effective Time"), each Solid Power option was converted into an option to purchase a number of shares of Common Stock of the Issuer, equal to the product (rounded down to the nearest whole number) of (x) the number of shares of Solid Power Common Stock subject to such Solid Power Option immediately prior to the Effective Time and (y) an exchange ratio calculated at closing (the "Exchange Ratio"), at an exercise price per share (rounded up to the nearest whole cent) equal to (A) the exercise price per share of such Solid Power Option immediately prior to the Effective Time divided by (B) the Exchange Ratio.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

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