Li-rich channels as the material gene for facile lithium diffusion in halide solid electrolytes

Halide solid electrolytes have attracted intense research interest recently for application in all-solid-state lithium-ion batteries. Herein, we present a systematic first-principles study of the Li3MX6 (M: multivalent cation; X: halogen anion) halide family that unveils the link between Li-rich channels and ionic conductivity, highlighting the former as a material gene in these compounds. By screening a total of 180 halides for those with high thermodynamic stability, wide electrochemical window, low chemical reactivity, and decent Li-ion conductivity, we identify seven unexplored candidates for solid electrolytes. From these halides and another four prototype compounds, we discover that the facile Li diffusion is rooted in the availability of diffusion pathways which can avoid direct connection with M cations—that is, where the local environment is Li-rich. These findings shed light on strategies for regulating cation and anion frameworks to establish Li-rich channels in the design of high-performance inorganic solid electrolytes. [Display omitted] •Seven novel Li-containing halides are identified via simulations to be potential solid electrolytes for Li-ion batteries.•Facile Li diffusion in halide solid electrolytes is found rooted in the availability of Li-rich channels.•Li-rich channel is a material gene that can be extended to other electrolyte systems and leveraged for compositional design.