Potassium tris(trifluoromethanesulfonyl)methide, commonly abbreviated as KTFSM, is an organometallic salt with the chemical formula K[C(SO₂CF₃)₃]. It is characterized by its exceptionally large, weakly coordinating anion, the tris(trifluoromethanesulfonyl)methide (TFSM⁻), which imparts high thermal stability, low nucleophilicity, and excellent solubility in various organic solvents. Its primary application is as a key component in advanced electrolytes for lithium-ion and other metal-ion batteries. The weakly coordinating nature of the TFSM⁻ anion facilitates high ionic conductivity and improves the stability of the solid-electrolyte interphase (SEI), leading to enhanced battery performance, especially at high voltages and temperatures. It is also investigated as a precursor for ionic liquids and as a super-strong, non-nucleophilic base in specialized organic synthesis, particularly for deprotonating very weak carbon acids. Due to its unique properties, KTFSM is a research-grade chemical of significant interest in materials science for energy storage applications. It requires careful handling under inert atmosphere (e.g., argon or nitrogen) due to its sensitivity to moisture and air.