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

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