High ionic conductivity materials LiYBrand LiLaBrfor 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 andmolecular dynamics simulations, we investigated the crystal structures of LiYBrand LiLaBr. 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 LiYBris 2.50 V. Through extrapolating various temperature diffusion results, the conductivity of LiYBrwas obtained at room temperature, approximately 3.9 mS cm, which is comparable to the experimental value 3.3 mS cm. LiLaBrhas a higher conductivity, a 100% increase compared with LiYBr. The activation energies of LiYBrand LiLaBrthrough 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 LiYBr. This research explored high ionic conductivity halide materials and will contribute to developing solid-state lithium-ion batteries.