Ionic Conductivity of Low-Crystalline Li4P2S6 and Li4P2S6-LiX (X=Cl, Br, and I) Systems and Their Role in Improved Positive Electrode Performance in All-Solid-State LiS Battery

摘要

Solid electrolytes strongly affect the performance of all-solid-state lithium-ion batteries. Therefore, they are required to have high ionic conductivity, interface-forming ability, and high stability. This study investigates low-crystalline Li(4)P(2)S(6)and Li4P2S6-LiX (X=Cl, Br, and I) systems as solid electrolytes. The low-crystalline Li(4)P(2)S(6)exhibits considerably higher ionic conductivity (4.7x10(-5) S cm(-1)) than the highly crystalline Li4P2S6. The Li4P2S6-LiX systems further improve the ionic conductivity while maintaining the P(2)S(6)(4-)structure. Especially, the 0.4Li(4)P(2)S(6) . 0.6LiI exhibits a relatively high ionic conductivity of 6.9x10(-4) S cm(-1), despite in low ionic conductive Li(4)P(2)S(6)systems. Furthermore, battery performance of the positive electrode using 0.4Li(4)P(2)S(6) . 0.6LiI for all-solid-state LiS battery considerably improves form that use highly crystalline Li4P2S6.