Solid Power, Inc.

To the shareholders and the Board of Directors of Solid Power, Inc

Opinion on the Financial Statements

We have audited the accompanying consolidated balance sheet of Solid Power, Inc and subsidiaries (the "Company") as of December 31, 2025, the related consolidated statements of operations and comprehensive loss, stockholders' equity, and cash flows, for the year ended December 31, 2025 and the related notes (collectively referred to as the "financial statements"). In our opinion, the financial statements present fairly, in all material respects, the financial position of the Company as of December 31, 2025 and the results of its operations and its cash flows for the year ended December 31, 2025, in conformity with accounting principles generally accepted in the United States of America (GAAP).

Basis for Opinion

These financial statements are the responsibility of the Company's management. Our responsibility is to express an opinion on the Company's financial statements based on our audit. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (PCAOB) and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audit in accordance with the standards of the PCAOB​. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud. The Company is not required to have, nor were we engaged to perform, an audit of its internal control over financial reporting. As part of our audit, we are required to obtain an understanding of internal control over financial reporting but not for the purpose of expressing an opinion on the effectiveness of the Company's internal control over financial reporting. Accordingly, we express no such opinion.​

Our audit included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our audit also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. We believe that our audit provides a reasonable basis for our opinion.

Critical Audit Matter

The critical audit matter communicated below is a matter arising from the current-period audit of the financial statements that was communicated or required to be communicated to the audit committee and that (1) relates to accounts or disclosures that are material to the financial statements and (2) involved our especially challenging, subjective, or complex judgments. The communication of critical audit matters does not alter in any way our opinion on the financial statements, taken as a whole, and we are not, by communicating the critical audit matter below, providing a separate opinion on the critical audit matter or on the accounts or disclosures to which it relates.

Revenue Recognition - Identification and evaluation of relevant terms and conditions in collaborative arrangements and application to such contracts of Accounting Standards Codification (ASC) Topic 606 – Revenue From Contracts With Customers (ASC 606) to determine overtime revenue to be recognized - Refer to Note 2 to the financial statements

Critical Audit Matter Description

The Company recognizes revenue from collaborative arrangements by applying the guidance within ASC 606. Revenue is recognized over time using a cost-to-cost method as performance obligations are fulfilled. The Company evaluates whether it will be subject to variable consideration under the terms of a contract and includes its estimate of variable consideration, subject to constraint, in the transaction price based on the most likely amount method when it is deemed probable of being realized based on historical experience and trends. The Company updates its estimate of the transaction price each reporting period, and the effect of variable consideration on the transaction price is recognized as an adjustment to revenue on a cumulative catch-up basis.

This application of ASC 606 to these arrangements involves complexity arising from the technical accounting involved in evaluating each agreement's terms and conditions and significant estimates regarding total project costs, completion costs, and transaction price. We identified revenue recognition and the application of ASC 606 under the SK On agreements as a critical audit matter due to the

challenging, subjective, and complex judgment required by management to develop these estimates. Auditing management’s estimates concerning revenue under these arrangements required significant auditor judgment and extensive effort to evaluate the reasonableness of management’s estimates.

How the Critical Audit Matter Was Addressed in the Audit

Our audit procedures related to revenue recognized under SK On agreements included the following, among others:

/s/ Deloitte & Touche LLP

Denver, CO

February 24, 2026

We have served as the Company's auditor since 2025.

Report of Independent** Registered Public Accounting Firm**

To the Stockholders and the Board of Directors of Solid Power, Inc.

Opinion on the Financial Statements

We have audited the accompanying consolidated balance sheet of Solid Power, Inc. (the Company) as of December 31, 2024, the related consolidated statements of operations and comprehensive loss, stockholders' equity and cash flows for the year ended December 31, 2024, and the related notes (collectively referred to as the “consolidated financial statements”). In our opinion, the consolidated financial statements present fairly, in all material respects, the financial position of the Company at December 31, 2024, and the results of its operations and its cash flows for the year ended December 31, 2024, in conformity with U.S. generally accepted accounting principles.

Basis for Opinion

These financial statements are the responsibility of the Company's management. Our responsibility is to express an opinion on the Company’s financial statements based on our audit. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (PCAOB) and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audit in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud. The Company is not required to have, nor were we engaged to perform, an audit of its internal control over financial reporting. As part of our audit we are required to obtain an understanding of internal control over financial reporting but not for the purpose of expressing an opinion on the effectiveness of the Company's internal control over financial reporting. Accordingly, we express no such opinion.

Our audit included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our audit also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. We believe that our audit provides a reasonable basis for our opinion.

/s/ Ernst & Young LLP

We served as the Company’s auditor from 2021 to 2025.

Denver, Colorado

February 28, 2025