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.