Exhibit 23.3

KPMG LLP

Bay Adelaide Centre

Suite 4600

333 Bay Street

Toronto, ON M5H 2S5

Tel 416-777-8500

Fax 416-777-8818

www.kpmg.ca

Consent of Independent Registered Public Accounting Firm

The Board of Directors

Electra Battery Materials Corporation

We consent to the use of our report dated April 4, 2023, on the consolidated financial statements of Electra Battery Materials Corporation (the “Entity”), which comprise the consolidated statements of income (loss) and other comprehensive income (loss), cash flows and shareholders’ equity for the year ended December 31, 2022, and the related notes (collectively the “consolidated financial statements”), which are incorporated by reference in the Registration Statement on Form F-3 of the Entity dated November 24, 2025 (“Registration Statement”) and to the reference to our firm under the heading “Interests of Experts” in the Registration Statement.

/s/ KPMG LLP

Chartered Professional Accountants, Licensed Public Accountants

November 24, 2025

Toronto, Canada

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