Mr. Daniel Rosen reports

SMACKOVER LITHIUM FILES DEFINITIVE FEASIBILITY STUDY FOR ITS SOUTH WEST ARKANSAS PROJECT, NORTH AMERICA'S HIGHEST-GRADE REPORTED LITHIUM BRINE RESERVE

Smackover Lithium, a 55:45-owned joint venture (JV) between Standard Lithium Ltd. and Equinor, has filed the definitive feasibility study for its South West Arkansas (SWA) project.

All figures are in U.S. dollars unless otherwise stated. All terms not otherwise defined have the meaning given to them under the CIM (Canadian Institute of Mining, Metallurgy and Petroleum) definition standards for mineral resources and mineral reserves.

The DFS contemplates production capacity of 22,500 tonnes per annum of battery-quality lithium carbonate over a 20-year modelled operating life, producing 447,000 tonnes (proven reserves) of lithium carbonate equivalent (LCE), or 38 per cent of the in situ measured and indicated resources of 1,177,000 tonnes LCE. The project will begin production at an average lithium concentration of 549 milligrams per litre and will process 0.50 cubic kilometre of brine over its modelled 20-year life at an average lithium concentration of 442 mg/L.

The report is highlighted by a 20.2-per-cent unlevered pretax internal rate of return (IRR), with competitive average cash operating costs of $4,516 per tonne and all-in costs of $5,924 per tonne over the operating life, and an all-in Class III capex estimate of $1.45-billion, which includes a 12.3-per-cent Monte Carlo-risked contingency.

The project maintains strong support from the local community, the State of Arkansas and the U.S. government. The project would mark the first commercial direct lithium extraction (DLE) operation in the United States and the first lithium production in the Smackover formation. It is intended as the first of several projects to be developed by the JV throughout the Smackover formation, and it is envisaged that the major design decisions and learnings from this first greenfield facility will form the basis for future expansion phases or projects, including in eastern Texas.

The development schedule for the project is estimated at 34 months from start of construction to the commercial operation date. The principal recommendation from the DFS is that the project is ready to progress to a final investment decision (FID). Construction is expected to commence in 2026 shortly after the FID, with first production targeted in 2028.

The report is available for review under the company's profile on SEDAR+ and on the company's website. For highlights of this report, please refer to the company's press release dated Sept. 3, 2025.

Qualified person

All scientific and technical disclosure in this news release was reviewed and approved by Stephen Ross, PGeo (British Columbia), vice-president of resource development for Standard Lithium and a qualified person for purposes of and as that term is defined in National Instrument 43-101, Standards of Disclosure for Mineral Projects. Mr. Ross is not independent of the company.

About Smackover Lithium

Smackover Lithium is a joint venture between Standard Lithium and Equinor. Formed in May, 2024, Smackover Lithium is developing two DLE projects in southwestern Arkansas and eastern Texas. Standard Lithium owns a 55-per-cent interest and Equinor holds the remaining 45-per-cent interest in the two JV projects, with Standard Lithium maintaining operatorship.

About Standard Lithium Ltd.

Standard Lithium is a leading near-commercial lithium development company focused on the sustainable development of a portfolio of large, high-grade lithium-brine properties in the United States. The company prioritizes projects characterized by high-grade resources, robust infrastructure, skilled labour and streamlined permitting. Standard Lithium aims to achieve sustainable, commercial-scale lithium production through the application of a scalable and fully integrated DLE and purification process. The company's flagship projects are located in the Smackover formation, a world-class lithium brine asset, focused in Arkansas and Texas. In partnership with global energy leader Equinor, Standard Lithium is advancing the SWA project, a greenfield project located in southern Arkansas, and actively advancing a promising lithium brine resource position in eastern Texas.

Standard Lithium trades on both the TSX Venture Exchange and the NYSE American exchange under the symbol SLI.

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