Improving the stability of NASICON-type electrolyte with Li metal anode by interfacial modification

Abstract

Sodium super-ionic conductors (NASICON)-type electrolyte Li1.4Al0.4Ti1.6(PO4)3 (LATP), with high ionic conductivity and low cost, is considered as one of the most attractive alternatives to liquid electrolytes. However, the poor interfacial compatibilities of LATP electrolyte in lithium batteries lead to the failure, which hinders its further development. Herein, a MoS2 coating layer as an artificial solid electrolyte interphase (ASEI) is used for modifying the surface of LATP (MCLATP) via an economical and uncomplicated spin coating method, which not only effectively inhibits the decomposition of LATP, but also in-situ forms a conversion layer consisting of Li2S and Mo metal during cycling. The conversion layer can improve the interfacial charge transfer kinetics and decrease the charge transfer resistance. According to interfacial modification of MoS2, the symmetric cells show slight polarization, and the Li/MCLATP/LFP cells demonstrate excellent cycling performance over 300 cycles at 1 C. The enhanced batteries performance is ascribed to interfacial modification of MoS2 as an ASEI layer, which reduces interfacial concentration polarization caused by the formed microcracks around the surface during decomposition of LATP. This work provides a promising strategy to construct the interface between Li metal and solid-state electrolytes for other unstable electrolytes beyond NASICON.