Plasma-Introduced Vacancies in VS2 for High-Performance Lithium-Ion Storage

VS2 has attracted attention as a prospective electrode material for lithium-ion batteries (LIBs) due to its distinct advantages including high conductivity and large layer spacing. However, the limited electrochemical activity and ionic conductivity restrict its real applications. In this work, sulfur vacancies (Vs) were introduced into VS2 via Ar plasma treatment for the first time in order to enhance the electrical conductivity, increase the number of electrochemically active sites, stabilize adsorption sites, and facilitate rapid Li+ diffusion. The designed Vs-rich VS2 delivers higher reversible capacity and better cycling stability (1137.5 mA h g–1 at 0.1 A g–1 after 100 cycles, 485.4 mA h g–1 at 1 A g–1 after 1000 cycles) than those of pristine VS2 (395.9 mA h g–1 at 0.1 A g–1 after 100 cycles, 204.4 mA h g–1 at 1 A g–1 after 1000 cycles). Moreover, the VS2–x//Li3V2(PO4)3/C full-cells exhibit high capacity and rate performance, holding promise for high-performance energy storage applications. Additionally, the insertion and conversion mechanisms of Vs-rich VS2 for Li+ storage were elucidated by ex situ X-ray diffraction (XRD) analysis. The density-functional theory (DFT) calculations show that sulfur vacancies favor Li+ adsorption on VS2 by increasing the number of adsorption sites and improving the adsorption energy. This study offers valuable insights for designing advanced anode materials for LIBs.