Thermodynamic and kinetic studies of the hydrolysis mechanism of halide solid state electrolytes Li ₃ MCl ₆ (M = In, Y)

All-solid-state batteries (ASSBs) utilizing solid-state electrolytes (SSEs) have emerged as a prominent research focus in energy storage technology, driven by their exceptional safety profile and superior energy density potential. Due to remarkable room-temperature Li⁺ conductivity, halide solid-state electrolytes (HSSEs) demonstrate unique applications among various SSE materials. In this paper, thermodynamic and kinetic studies of the hydrolysis mechanism of HSSEs Li₃MCl₆ (M = In, Y) were systematically investigated through first principles calculations. The reaction sites were determined by analyzing the surface energy, electronic structure, and adsorption energy. Reaction path calculations revealed the formation mechanism of key intermediates and the kinetics of O^2- and Cl^- diffusion. Besides, substitution of Cl atoms by O atoms explains the material thermodynamic stability. The mechanism revealed in this research provides crucial insights for developing next-generation anti-hydrolysis solid electrolyte materials.