Electron and Ion Co-Conductive Catalyst Achieving Instant Transformation of Lithium Polysulfide towards Li2 S.

Abstract

Most of the catalysts in lithium sulfur (Li-S) batteries present low electronic conductivity and the lithium polysulfides (LiPSs) must diffuse onto the surface of the carbon materials to achieve their conversion reaction. It is a significant challenge to achieve the instantaneous transformation of LiPSs to Li2 S in Li-S batteries to suppress the shuttle effect of LiPSs. Herein, a unique electron and ion co-conductive catalyst of carbon-coated Li1.4 Al0.4 Ti1.6 (PO4 )3 (C@LATP) is developed, which not only possesses strong adsorption to LiPSs, but, more importantly, also promotes the instantaneous conversion reaction of LiPSs to Li2 S. The C@LATP nanoparticles as catalytic active sites can synchronously and efficiently provide both Li ions and electrons to facilitate the conversion reaction of LiPSs. The conversion reaction path of LiPSs using C@LATP changes from traditional "adsorption-diffusion-conversion" to novel "adsorption-conversion," which effectively lowers the decomposition barrier of Li2 S6 and promotes faster conversion of LiPSs. The shuttle effect of LiPSs is considerably suppressed and utilization of sulfur is greatly improved. The Li-S batteries using C@LATP present excellent rate, cycling, and self-discharge properties. This work highlights the significance of electron and ion co-conductive solid-state electrolytes for the instantaneous transformation of LiPSs in advanced Li-S batteries.