Unveiling the synergy of Interface and defects in V2O3/VN heterojunctions for high-performance aqueous zinc-ion batteries.

Abstract

Aqueous zinc-ion batteries (AZIBs) represent promising candidates for large-scale energy storage owing to their inherent safety, low cost, and environmental friendliness. However, developing cathode materials that simultaneously achieve high capacity and long-term cycling stability remains a critical challenge. Herein, we report the rational design and synthesis of a series of Vanadium trioxide/Vanadium nitride (V₂O₃/VN) heterostructured composites through a controlled partial nitridation process using a vanadium-based metal-organic framework as a precursor. This strategy enables the in-situ formation of a conductive carbon matrix and the construction of an intimate heterointerface between V₂O₃ and VN. A key innovation lies in the precise tuning of the V₂O₃-to-VN ratio, which governs the heterostructure morphology, defect concentration, and resulting electrochemical properties. The optimized V₂O₃/VN composite leverages the complementary attributes of its constituents: the structural stability and high theoretical capacity of V₂O₃, along with the superior electrical conductivity and electrochemical activity of VN. Synergistic effects at the heterointerface not only facilitate rapid electron and ion transport but also effectively accommodate volume variations during repeated cycling. Moreover, the presence of oxygen vacancies enhances Zn²⁺ adsorption and diffusion kinetics. Therefore, the V₂O₃/VN cathode delivers a high specific capacity of 528 mAh g^-1 at 0.1 A g^-1, and retains 244 mAh g^-1 after 2000 cycles at 5 A g^-1, corresponding to a capacity fading rate of 0.025% per cycle. This work highlights the critical roles of component ratio optimization and interface engineering, providing a promising strategy for the development of advanced AZIB cathodes.