Selenium Defect Boosted Electrochemical Performance of Binder-Free VSe₂ Nanosheets for Aqueous Zinc-Ion Batteries

As a typical transition-metal dichalcogenides, vanadium diselenide (VSe 2 ) is a promising electrode material for aqueous zinc-ion batteries due to its metallic characteristics and excellent electronic conductivity. In this work, we propose a strategy of hydrothermal reduction synthesis of stainless-steel (SS)-supported VSe 2 nanosheets with defect (VSe 2– x -SS), thereby further improving the conductivity and activity of VSe 2– x -SS. Density functional theory calculations confirmed that Se defect can adjust the adsorption energy of Zn 2+ ions. This means that the adsorption/desorption process of Zn 2+ ions on VSe 2– x -SS is more reversible than that on pure SS-supported VSe 2 (VSe 2 -SS). As a result, the Zn//VSe 2– x -SS battery showed more excellent electrochemical performance than Zn//VSe 2 -SS. The VSe 2– x -SS electrode shows a good specific capacity of 265.2 mA h g –1 (0.2 A g –1 after 150 cycles), satisfactory rate performance, and impressive cyclic stability. In addition, we also have explored the energy-storage mechanism of Zn 2+ ions in this VSe 2– x -SS electrode material. This study provides an effective strategy for the rational design of electrode materials for electrochemical energy-storage devices.