Interlayer-expanded and binder-free VS2 nanosheets assemblies for enhanced Mg2+ and Li+/Mg2+ hybrid ion storage

Abstract

Magnesium ion batteries (MIBs) and magnesium/lithium hybrid ion batteries (MLIBs) are promising candidates for next-generation energy storage, due to the large capacity, abundant magnesium reserves, and safe operation. Nevertheless, the use of MIBs and MLIBs is limited by sluggish Mg2+ kinetics and Li+-dependent storage in cathode materials, respectively. Herein, an efficient interlayer expansion strategy is employed to deal with the problems in both MIBs and MLIBs based on VS2. The interlayer spacing of VS2 is enlarged to 1.0 nm by octylamine intercalations via one-pot solvothermal reaction, generating dramatically enhanced electrochemical performance in MIBs and MLIBs. Moreover, various ex situ methods are used to confirm a Li+/Mg2+ co-intercalation in the expanded VS2, with most of the capacity controlled by pseudo-capacitance. This work expands the application of interlayer expansion strategy to enhance magnesium ion and lithium/magnesium hybrid ion storage.