Identifying lithium fluorides for promising solid-state electrolyte and coating material of high voltage cathode

Abstract Halide materials are of current interest for all-solid-state batteries. In this study, we systematically studied seven fluorides Li3MF6 (M = Al, Sc, Ti, V, Cr, Ga, In) using density functional theory combined with molecular dynamics simulation and the grand potential phase diagram analysis. Among them, Li3ScF6 is identified to be a promising solid electrolyte for lithium ion batteries with high Li ionic conductivity of 0.28 mS/cm at room temperature, wide electrochemical window of 0.59-6.38 V and excellent interfacial stability with high voltage cathodes including LiMn1.5Ni0.5O4 (4.7 V), LiCoPO4 (4.8 V) and LiNiPO4 (5.1 V). Besides, Li3AlF6 is identified as a potential coating material with high anodic limit of 6.48 V and good compatibility with cathodes and sulfide-based solid electrolytes. This study expands the family of halide materials for battery applications.