Tailoring the electronic structure and kinetics of VSe2via selenium vacancy engineering for ultralong-life zinc-ion batteries

Abstract

Vanadium diselenide (VSe₂), a typical transition metal dichalcogenide (TMD), is considered a promising cathode material for aqueous zinc-ion batteries (AZIBs) owing to its large interlayer spacing, high electronic conductivity, and tunable interfacial properties. However, its practical application is hindered by limited specific capacity and poor cycling stability. Herein, an anion defect engineering strategy is proposed to achieve multiscale regulation of the interfacial structure and electronic states of VSe₂, enabling the successful construction of a VSe_2−x-40 cathode with enhanced utilization of active sites. The introduction of selenium vacancies not only creates additional Zn²⁺ storage sites but also reconstructs the electronic structure, thereby accelerating ion diffusion kinetics. Meanwhile, the synergistic effect between selenium vacancies and the intrinsic layered structure effectively buffers volume variation during cycling, ensuring structural stability. Density functional theory (DFT) calculations further confirm that selenium vacancies enhance electronic conductivity, reduce Zn²⁺ diffusion barriers, and weaken the interaction between Zn²⁺ and the host lattice. As a result, the VSe_2−x-40 cathode delivers a high specific capacity of 359.3 mAh g⁻¹ at 1 A g⁻¹ and retains 80.2% of its capacity after 5000 cycles at 10 A g⁻¹. Mechanistic analysis reveals a pseudocapacitive Zn²⁺ storage behavior based on interfacial adsorption–intercalation, achieving a high energy density of 248.4 Wh kg⁻¹ at a power density of 746.1 W kg⁻¹. This work provides a new paradigm for the rational design of high-performance TMD cathodes.