Ad hoc announcement pursuant to Art. 53 LR

YVERDON-LES-BAINS, Switzerland, 30^th of April, 2026 –, In its decision of April 29, 2026, SIX Exchange Regulation AG approved an extension of the publication deadline of Leclanché SA‘s (SIX: LECN) (“Leclanché” or the “Company“) 2025 annual report until May 31, 2026.

Leclanché encountered several obstacles in the finalisation of its 2025 annual report including:

• Following the departure of the previous Chief Financial Officer on 30 November 2025, the Company’s finance department was supported by a reputable accounting firm until the end of March 2026. As of 1 March 2026, Jens Emrich was appointed Chief Financial Officer. This transition occurred during a financially challenging period for the Company and required additional time to ensure a comprehensive handover and the proper consolidation and review of financial information for the annual reporting process.
• Further, the Company is currently implementing a debt-to-equity conversion of a portion of its outstanding debt, as requested by its auditors prior to the finalisation of the 2025 financial statements. Due to the number of parties involved, the conversion could not be completed within the initially envisaged timeline; completion is, however, expected shortly. The completion of the debt-to-equity conversion – amongst other reasons – also led to the late completion of the closing process for both the consolidated accounts and the annual accounts of its subsidiaries.

The Company is continuing to work on closing the remaining outstanding items with its auditors and board of directors and remains confident that it will be able to publish its 2025 annual report before or on May 31, 2026.

Leclanché is releasing its unaudited key financial figures for the year 2025: In 2025, the Company’s consolidated income reached CHF 23.1 million, with customer revenue totaling CHF 22.4 million, representing an increase of CHF 5.0 million, or approximately 29% year-over-year.

The Company recorded an unaudited EBIT of CHF (65.3) million and an EBITDA of CHF (57.7) million, resulting in an unaudited net loss of CHF (72.9) million for the year. On a consolidated basis, the annual result was significantly impacted by a one-off impairment of CHF 7.6 million related to the St. Kitts project.

As of December 31, 2025, the balance sheet total amounted to CHF 92.1 million, compared to CHF 108.9 million in the previous year. Total equity stood at CHF (16.9) million.

In its decision of April 29, 2026, SIX Exchange Regulation AG requested Leclanché to insert the below excerpt in this ad hoc announcement:

1. The temporary exemption from the publication of the 2025 annual report and to file such report with SIX Exchange Regulation AG until 31 May 2026 at the latest is granted with the following reservation (lit. a) and under the following conditions (lit. b):
   a. SIX Exchange Regulation AG will usually suspend trading of the registered shares of Leclanché SA in the short term according to Art. 57 of the Listing Rules [LR] in case its 2025 annual report is not published in accordance with the provisions on ad hoc publicity (Art. 53 LR in connection with the Directive on Ad hoc Publicity [DAH]) and not filed with SIX Exchange Regulation AG until Sunday, 31 May 2026, 11.59 pm CET, at the latest.
   b. Leclanché SA is required to publish a notice in accordance with the provisions on ad hoc publicity concerning this decision until Thursday, 30 April 2026, 7.30 am CET, at the latest. The notice must contain:

• the unaltered reproduction of the wording of para. I. of this decision, placed in a prominent position;
• the reasons for the application of the Issuer requesting an extension of the deadline to publish its 2025 annual report and to file such report with SIX Exchange Regulation AG;
• the unaudited key figures regularly published by the issuer, in particular net revenue, EBITDA, EBIT, net profit/loss, balance sheet total, equity capital in relation to the issuer’s annual results 2025;

For more information, write to info@leclanche.com or visit www.leclanche.com.

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About Leclanché

Leclanché is a world leading provider of low-carbon footprint energy storage solutions based on lithium-ion cell technology. Established in 1909 in Yverdon-les-Bains, Switzerland, Leclanché’s history and heritage is rooted in battery and energy storage innovation. The company’s Swiss culture for precision and quality, together with its production facilities in Germany, make Leclanché the partner of choice for companies seeking the very best in battery performance and who are pioneering positive changes in how energy is produced, distributed and consumed around the world. Leclanché is organised into three business units: energy storage solutions, e-Mobility solutions and specialty battery systems. The company currently employs over 350 people with representative offices in eight countries around the world. Leclanché is listed on the Swiss Stock Exchange (SIX: LECN).

SIX Swiss Exchange : ticker symbol LECN | ISIN CH 011 030 311 9

Disclaimer

This press release contains certain forward-looking statements relating to Leclanché’s business, which can be identified by terminology such as “strategic”, “proposes”, “to introduce”, “will”, “planned”, “expected”, “commitment”, “expects”, “set”, “preparing”, “plans”, “estimates”, “aims”, “would”, “potential”, “awaiting”, “estimated”, “proposal”, or similar expressions, or by expressed or implied discussions regarding the ramp up of Leclanché’s production capacity, potential applications for existing products, or regarding potential future revenues from any such products, or potential future sales or earnings of Leclanché or any of its business units. You should not place undue reliance on these statements. Such forward-looking statements reflect the current views of Leclanché regarding future events, and involve known and unknown risks, uncertainties and other factors that may cause actual results to be materially different from any future results, performance or achievements expressed or implied by such statements. There can be no guarantee that Leclanché’s products will achieve any particular revenue levels. Nor can there be any guarantee that Leclanché, or any of the business units, will achieve any particular financial results.

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