Li+ transportation mechanisms in the halide solid state electrolytes Li3YCl6 and Li3InCl6

Developing outstanding halide solid state electrolytes (SSE) has attracted a lot of attentions in the area of all-solid-state batteries (ASSBs), owing to their excellent compatibilities towards the high voltage active materials. In the halide compounds, Li+ ions are usually confined in the center of octahedron units, which seriously impede the fast transportation of Li+ ions. However, the representative SSEs, Li3YCl6 and Li3InCl6, present ultrafast ionic conductivities below 0.1 mS cm−1 at room temperature, which may have close connections with their particular configurations. Through the assessments on the transportation mechanisms in Li3YCl6 and Li3InCl6 by the careful DFT simulations, two kinds of Li+ ion diffusion channels can be identified. Besides, the overall performances of Li3YCl6 and Li3InCl6, including energetic stability, electronic chemical window, electronic structures, are systematically studied. It will bring deep insights and reliable criteria to explore next generation halide solid state electrolytes.