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 (V_s) 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 V_s-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 VS_2-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 V_s-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.