Mr. Daniel Rosen reports

STANDARD LITHIUM FILES POSITIVE PRELIMINARY ECONOMIC ASSESSMENT FOR THE HIGH-GRADE 70,000 TONNES PER YEAR FRANKLIN PROJECT IN EAST TEXAS

Standard Lithium Ltd., in partnership with Equinor, has filed on SEDAR+ the preliminary economic assessment technical report for the Franklin project in the northeastern region of Texas, United States.

The report for the Franklin project, the partnership's first defined project area in the East Texas region of the Smackover formation, highlights the globally significant size and high quality of its brine position. The report marks a key step toward the partnership's goal of reaching over 100,000 tonnes of lithium chemical production per year in Texas through multiple phases and projects.

The PEA contemplates annual production capacity of up to 70,000 tonnes of battery-quality lithium carbonate and 1.29 million tonnes of total lithium carbonate production over a 20-year modelled operating life, with a starting lithium concentration of 562 milligrams per litre and an average lithium concentration of 515 mg/L. Initial production could begin in the early 2030s, with additional potential for a longer operating life and further expansion, though this is not modelled in the report.

The PEA for the lithium project is highlighted by attractive economics, including an unlevered pretax net present value (NPV8) of $5.9-billion, an internal rate of return (IRR) of 25.7 per cent and a three-year payback period, along with average annual lithium cash operating cost of $4,226 per tonne and a capital intensity of $49,945 per tonne. Additionally, it includes an upgraded and upsized mineral resource with some of the highest lithium-in-brine concentrations reported in North America. This is supported by an increase in the project area by 37 per cent since the prior maiden inferred resource report to 44,541 hectares (110,064 acres).

The report also considers a scenario based on a co-located bromine facility of 50,000 tonnes per year alongside the lithium operation. Standard Lithium and Equinor anticipate further evaluating potential commercial opportunities for both bromine and potash given the significant scale and quality of the resources as well as the designation of potash as a U.S. critical mineral in 2025.

The principal recommendation of the PEA is to advance the Franklin project to a preliminary feasibility study (PFS). The partnership will continue to conduct direct lithium extraction (DLE) testing of the project brine, leveraging insights gained at Standard Lithium's demonstration plant as well as at the South West Arkansas (SWA) project.

All figures are in U.S. dollars and all units are metric unless otherwise stated. All model outputs are expressed on a 100-per-cent-ownership basis with no adjustments for financing assumptions. Standard Lithium's economic interest in the project is 55 per cent. Mineral resources have been reported in accordance with the 2014 Canadian Institute of Mining, Metallurgy and Petroleum Definition Standards for Mineral Resources and Mineral Reserves.

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 news release dated Sept. 8, 2026.

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 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 in the Smackover formation, an attractive 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 East Texas, including the highest known lithium brine grade project in North America, the Franklin project.

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

About Smackover Lithium

Smackover Lithium is a partnership between Standard Lithium and Equinor, through subsidiaries of Equinor ASA. Formed in May, 2024, Smackover Lithium is developing multiple DLE projects in southwestern Arkansas and East Texas. Standard Lithium owns a 55-per-cent interest and Equinor holds the remaining 45-per-cent interest in the projects, with Standard Lithium maintaining operatorship.

We seek Safe Harbor.