Boosting reaction kinetics and reversibility in Mott-Schottky VS2/MoS2 heterojunctions for enhanced lithium storage

Abstract

Heterostructures have lately been recognized as a viable implement to achieve high-energy Li-ion batteries (LIBs) because the as-formed built-in electric field can greatly accelerate the charge transfer kinetics. Herein, we have constructed the Mott-Schottky heterostructured VS2/MoS2 hybrids with tailorable 1T/2H phase based on their matchable formation energy, which are made of metallic and few-layered VS2 vertically grown on MoS2 surface. The density functional theory (DFT) calculations unveil that such heterojunctions drive the rearrangement of energy band with a facilitated reaction kinetics and enhance the Li adsorption energy more than twice compared to the MoS2 surface. Furthermore, the VS2 catalytically expedites the Li–S bond fracture and meantime the enriched Mo6+ enables the sulfur anchoring toward the oriented reaction with Li+ to form Li2S, synergistically enhancing the reversibility of electrochemical redox. Consequently, the as-obtained VS2/MoS2 hybrids deliver a very large specific capacity of 1273 mAh g−1 at 0.1 A g−1 with 61% retention even at 5 A g−1. It can also stabilize 100 cycles at 0.5 A g−1 and 500 cycles at 1 A g−1. The findings provide in-depth insights into engineering heterojunctions towards the enhancement of reaction kinetics and reversibility for LIBs.