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

Abstract 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 Li 6 PS 5 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 impact on Li‐ion diffusivity in the lattice. The phase at the limit of the solid solution regime, Li 5.5 PS 4.5 Cl 1.5 , exhibits a cold‐pressed conductivity of 9.4±0.1 mS cm −1 at 298 K (and 12.0±0.2 mS cm −1 on sintering)—almost four‐fold greater…

• B
  BASF
• NS
  Natural Sciences and Engineering Research Council of Canada