Polyaniline-coated VS4@rGO nanocomposite as high-performance cathode material for magnesium batteries based on Mg2+/Li+ dual ion electrolytes

Abstract

Magnesium batteries based on Mg2+/Li+ dual ion electrolytes (MLIBs) have attracted increasing attention due to fast Li+ or Mg2+/Li+ insertion kinetics, abundant Mg resources, and high volumetric capacity of dendrite-free Mg anodes. Herein, we report polyaniline (PANI)–coated VS4@reduced graphene oxide (rGO) with nanostructures synthesized via hydrothermal synthesis and subsequent PANI polymerization as the cathode material for MLIBs. The PANI layer serves as a conductive medium to enhance electron transfer and Mg2+/Li+ transportation as well as to mitigate the structure changes of VS4 during the cycling process. Indeed, this material demonstrates enhanced electrochemical performance with a high discharge capacity of 200.7 mAh g−1 after 20 cycles and 91.2% retention after 50 cycles. Mechanism analysis reveals that Li+ insertion into VS4 produced an amorphous VS4 host in the first discharge, which inclined to store Mg2+ rather than Li+ in the subsequent cycles. Our study provides new insights into the development of amorphous electrode materials for magnesium batteries.