High ionic conductivity materials Li3YBr6and Li3LaBr6for solid-state batteries: first-principles calculations.

High ionic conductivity solid-state electrolytes are essential for powerful solid-state lithium-ion batteries. With density functional theory andab initiomolecular dynamics simulations, we investigated the crystal structures of Li₃YBr₆and Li₃LaBr₆. The lowest energy configurations with uniform distribution of lithium ions were identified. Both materials have wide electrochemical stability windows (ESW): 2.64 V and 2.57 V, respectively. The experimental ESW for Li₃YBr₆is 2.50 V. Through extrapolating various temperature diffusion results, the conductivity of Li₃YBr₆was obtained at room temperature, approximately 3.9 mS cm^-1, which is comparable to the experimental value 3.3 mS cm^-1. Li₃LaBr₆has a higher conductivity, a 100% increase compared with Li₃YBr₆. The activation energies of Li₃YBr₆and Li₃LaBr₆through the Arrhenius plot are 0.26 eV and 0.24 eV, respectively, which is also close to the experimental value of 0.30 eV for Li₃YBr₆. This research explored high ionic conductivity halide materials and will contribute to developing solid-state lithium-ion batteries.