High-entropy sulfide argyrodite electrolytes for all-solid-state lithium-sulfur batteries

Abstract

Solid-state electrolytes (SEs) hold the potential to overcome challenges that hinder the commercialization of lithium-sulfur batteries. However, their limited ionic conductivity makes lithium (Li) ion transport a critical bottleneck in accessing the superior capacity of sulfur. In this study, we investigate high-entropy Cl,Br-co-doped sulfide argyrodites as SEs in Li-sulfur (S) all-solid-state batteries (ASSBs). Li 5.7 PS 4.7 Cl 0.65 Br 0.65 exhibits an ionic conductivity of 6.9 mS cm − 1 at room temperature with an activation energy of 0.28 eV, thanks to its high configurational entropy. The electrolyte with suitable cathodic stability and high ionic conductivity allows S composite cathodes to deliver an areal capacity over 6 mAh cm − 2 when cycled with Li-In anodes. The reduced porosity of the SE separator and the formation of a passivating interphase with metallic Li enable Li-S ASSBs to cycle without short circuits, achieving an S utilization of over 75% at 0.1 C.