Dr. Andy Robinson reports

STANDARD LITHIUM DRILLS AND SAMPLES HIGHEST CONFIRMED GRADE LITHIUM BRINE IN ARKANSAS

As part of the resource definition work at its South West Arkansas project (see news release dated March 20, 2023), Standard Lithium Ltd. has sampled, to the best of its knowledge, the highest confirmed lithium-grade brine in Arkansas, with a grade of 581 milligrams/litre. These sampling data follow similar high-grade results from the company's resources in Texas (see news release dated March 28, 2023).

Dr. Andy Robinson, president and chief operating officer of Standard Lithium, commented: "We continue to be very pleasantly surprised by the lithium grades sampled from our projects in Arkansas and Texas. We previously developed the preliminary economic assessment (PEA) for the SWA project using a conservative assessment of the lithium brine grades across the project area. Using that conservative resource basis still yielded a PEA with very attractive project economics (after-tax NPV $1.97-billion (U.S.) and IRR of 32 per cent at 8-per-cent discount rate; see news release dated Oct. 12, 2021). This recent infill drilling work to further define the lithium resource has resulted in a marked upside to the in situ lithium grade. In our experience, the grade of lithium in brine used for direct lithium extraction (DLE) has a meaningful impact on both capital expenditures and operating costs in connection with the extraction process, so a higher grade typically results in lower overall costs and should have a positive effect on project economics in the forthcoming preliminary feasibility study (PFS). We are delighted that sampling from this recent well has led us to find lithium brine with the highest confirmed grade in Arkansas, and we look forward to incorporating these into the forthcoming PFS."

Analysis and testing details

The lithium brine samples were taken from a pre-existing well located in the central-eastern portion of Standard's project area. This well (the Beulah-Taylor No. 1) was first drilled in July, 1982, and subsequently decommissioned in August, 1982. Standard Lithium's drilling team commenced drilling on Feb. 21, 2023, and deepened the hole to a total measured depth of 8,940 feet on March 8, 2023 (see news release dated March 20, 2023).

Brines from the Beulah-Taylor No. 1 were sampled using a workover rig from several different zones in the Smackover formation during March and early April, and the lithium concentrations of those samples are reported herein. All brine samples were analyzed at multiple analytical laboratories (both third party and also at the company's analytical facility in El Dorado, Ark.) in order to confirm sample quality and maintain quality assurance/quality control procedures. The Standard Lithium data provided herein were all analyzed, performed and reported by Western Environmental Testing Laboratories of Sparks, Nev., a third party, accredited testing facility.

Quality assurance

Steve Ross, PGeol, a qualified person as defined by National Instrument 43-101, has reviewed and approved the relevant scientific and technical information that forms the basis for this news release. Mr. Ross is a consultant to the company.

About Standard Lithium Ltd.

Standard Lithium is a leading near-commercial lithium development company with a portfolio of projects in process. The company's flagship projects, the Lanxess property project and the South West Arkansas project, are located in southern Arkansas near the Louisiana state line. The company is focused on the evaluation and testing of commercial lithium extraction and purification from brine sourced from approximately 180,000 acres of leases across these two projects. The company operates a first-of-its-kind industrial-scale direct lithium extraction (DLE) demonstration plant at the Lanxess property project. The scalable, environmentally friendly process eliminates the use of evaporation ponds, reduces processing time from months to hours and greatly increases the effective recovery of lithium. A definitive feasibility study (DFS) and front-end engineering study (FEED) for phase 1A of the Lanxess property project commenced in September, 2022. A preliminary feasibility study (PFS) of the South West Arkansas project commenced in May, 2022. The company is also pursuing the resource development of other projects in the Smackover formation in east Texas, as well as approximately 45,000 acres of mineral leases located in the Mojave Desert in San Bernardino county, California.

We seek Safe Harbor.