Local Bonding and Reconstruction Enhancing Ion Transport in Li₃InCl₆

Developing solid-state electrolytes with high ionic conductivity has been recognized as crucial for advancing all-solid-state batteries. Enhancing the ionic conductivity of solid-state electrolytes crucially depends on establishing the relationship between microstructure and ion transport. This study employs the aliovalent Nb⁵⁺ doping strategy to successfully create a favorable microstructural environment in the halide solid-state electrolyte Li₃InCl₆ that facilitates rapid Li⁺ transport. The introduction of Nb⁵⁺ is found to significantly optimize the Li⁺ migration pathways by triggering a local structural distortion. Further electronic structure analysis reveals that the formation of strong Nb─Cl bonds concurrently weaken the Li─Cl interactions, which is crucial for enhancing ionic conductivity. This synergistic microstructural optimization enables the optimal composition, Li_2.84In_0.92Nb_0.08Cl₆, to achieve a room-temperature ionic conductivity of 1.03 mS cm^-1 and an activation energy of 0.305 eV. Furthermore, Nb⁵⁺ doping effectively suppresses the electronic conductivity and mitigates side reactions between the electrolyte and Li metal, thereby enabling all-solid-state batteries to exhibit exceptional long-term cycling stability. This work elucidates the regulation mechanism of local bond reorganization through cation doping, thereby providing important insights for the rational design of high-performance halide solid-state electrolytes.