Fluorine-Doped Antiperovskite Electrolyte for All-Solid-State Lithium-Ion Batteries

A fluorine-doped antiperovskite Li-ion conductor Li-2(OH)X (X=Cl, Br) is shown to be a promising candidate for a solid electrolyte in an all-solid-state Li-ion rechargeable battery. Substitution of F- for OH- transforms orthorhombic Li2OHCl to a room-temperature cubic phase, which shows electrochemical stability to 9 V versus Li+/Li and two orders of magnitude higher Li-ion conductivity than that of orthorhombic Li2OHCl. An all-solid-state Li/LiFePO4 with F-doped Li2OHCl as the solid electrolyte showed good cyclability and a high coulombic efficiency over 40 charge/discharge cycles.