Selenium Defect Boosted Electrochemical Performance of Binder-Free VSe₂ Nanosheets for Aqueous Zinc-Ion Batteries
2021
Bai, Youcun | Zhang, Heng | Xiang, Bin | Liang, Xinyue | Hao, Jiangyu | Zhang, Chong | Yan, Lijin
As a typical transition-metal dichalcogenides, vanadium diselenide (VSe₂) 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 VSe₂ nanosheets with defect (VSe₂–ₓ-SS), thereby further improving the conductivity and activity of VSe₂–ₓ-SS. Density functional theory calculations confirmed that Se defect can adjust the adsorption energy of Zn²⁺ ions. This means that the adsorption/desorption process of Zn²⁺ ions on VSe₂–ₓ-SS is more reversible than that on pure SS-supported VSe₂ (VSe₂-SS). As a result, the Zn//VSe₂–ₓ-SS battery showed more excellent electrochemical performance than Zn//VSe₂-SS. The VSe₂–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 Zn²⁺ ions in this VSe₂–ₓ-SS electrode material. This study provides an effective strategy for the rational design of electrode materials for electrochemical energy-storage devices.
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