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

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.

Automated summary

In this study, VSe2 nanosheets supported on stainless-steel with defects were synthesized through a hydrothermal reduction strategy, resulting in improved conductivity and activity. The Se defect was found to adjust the adsorption energy of Zn2+ ions, leading to enhanced reversibility and electrochemical performance of the Zn// VSe2-x-SS battery. The VSe2-x-SS electrode exhibited good specific capacity, rate performance, and cyclic stability, providing insights into the energy-storage mechanism of Zn2+ ions in this material for future electrode design.