Boosting Solid‐State Diffusivity and Conductivity in Lithium Superionic Argyrodites by Halide Substitution

Developing high-performance all-solid-state batteries is contingent on finding solid electrolyte materials with high ionic conductivity and ductility. Here we report new halide-rich solid solution phases in the argyrodite Li₆ PS₅ Cl family, Li_6-x PS_5-x Cl_1+x , and combine electrochemical impedance spectroscopy, neutron diffraction, and ⁷ Li NMR MAS and PFG spectroscopy to show that increasing the Cl^- /S^2- ratio has a systematic, and remarkable …