Mechanochemical synthesis of Li-argyrodite Li6PS5X (X = Cl, Br, I) as sulfur-based solid electrolytes for all solid state batteries application

Highly ion-conductive Li6PS5X (X = Cl, Br, I) Li-argyrodites were prepared through a high‐energy ball milling. Electrical and electrochemical properties were investigated. Ball-milled compounds exhibit a high conductivity between 2 and 7 × 10− 4 S/cm with an activation energy of 0.3–0.4 eV for conduction. These attractive properties were attributed to the spontaneous formation of crystallized Li-argyrodite during ball-milling. An optimization of milling time led to a conductivity of 1.33 × 10− 3 S/cm for the Li6PS5Cl phase with an electrochemical stability up to 7 V vs. lithium. An all solid state LiCoO2/Elec./In lithium ion battery using ball-milled Li6PS5Cl as electrolyte was successfully assembled, and its room temperature performance is reported.

► Revisited synthesis of sulfur-based solid electrolyte for all solid state batteries.
► Argyrodite phase formed by high-energy ball milling synthesis.
► Wide electrochemical stability window from 0 to 7 V vs. Li.
► High ionic conductivity of 1.33 × 10− 3 S/cm for ball-milled Li6PS5Cl sample at room temperature.
► Reversible capacity of 100 mAh/g using LiCoO2 in all solid state battery.