The UPBEAT project (France 2030) aims to develop a low-cost potassium-ion technology that is free of critical materials and capable of providing the performance of LiFePO4-type Li-ion cells. The work proposed to the post-doc is in line with this objective: after having optimized the upscaled synthesis of the positive electrode active material, it will involve developing optimized organic liquid electrolytes for this new system (Prussian White vs. Graphite), by studying the most promising salts, solvents, and additives, while maintaining the objectives of cost and durability. The proposed solutions (with and without fluorine) will be formulated, characterized, and electrochemically tested in complete cells (coin cells and pouch cells, including component optimizations) to measure their effectiveness in terms of lifetime and power response. Operando measurements and post-mortem characterizations will be used to understand the effects of the various components. The systems that best meet the project's requirements will also be subjected to abuse tests to assess the safety of the final system.