Cl- and Al-Doped Argyrodite Solid Electrolyte Li 6 PS 5 Cl for All-Solid-State Lithium Batteries with Improved Ionic Conductivity.

Argyrodite solid electrolytes such as lithium phosphorus sulfur chloride (Li 6 PS 5 Cl) have recently attracted great attention due to their excellent lithium-ion transport properties, which are applicable to all-solid-state lithium batteries. In this study, we report the improved ionic conductivity of an argyrodite solid electrolyte, Li 6 PS 5 Cl, in all-solid-state lithium batteries via the co-doping of chlorine (Cl) and aluminum (Al) elements. Electrochemical analysis was conducted on the doped argyrodite structure of Li 6 PS 5 Cl, which revealed that the substitution of cations and anions greatly improved the ionic conductivity of solid electrolytes. The ionic conductivity of the Cl- and Al-doped Li 6 PS 5 Cl (Li 5.4 Al 0.1 PS 4.7 Cl 1.3 ) electrolyte was 7.29 × 10 -3 S cm -1 at room temperature, which is 4.7 times higher than that of Li 6 PS 5 Cl. The Arrhenius plot of the Li 5.4 Al 0.1 PS 4.7 Cl 1.3 electrolyte further elucidated its low activation energy at 0.09 eV.