Dual ion insertion and oxygen vacancy engineering in nanostructured V2O5 cathodes for enhanced Zn-ion battery performance and stability

This study explores the impact of oxygen vacancies and dual ion (Zn²⁺ and H⁺) insertion on the electrochemical performance of V₂O₅ layered cathodes in aqueous zinc-ion batteries (AZIBs). Oxygen vacancies were introduced into the V₂O₅ lattice through a controlled synthesis process, and their effect on electrochemical properties was thoroughly analyzed using structural, morphological, and electrochemical characterizations. The findings reveal that the introduction of oxygen vacancies, combined with dual ion insertion during charge-discharge cycles, significantly enhances the rate capability and cycling stability of oxygen-deficient V₂O₅ (OD-V₂O₅) cathodes. These enhancements are attributed to accelerated ion diffusion kinetics and reduced structural degradation, which result from the presence of oxygen vacancies. This facilitates more efficient zinc-ion insertion and extraction, while also minimizing irreversible capacity loss, leading to improved long-term cycling stability. The OD-V₂O₅ nanosheets exhibit exceptional electrochemical performance, with a specific capacity of 477 mAh g⁻¹ at 0.1 A g⁻¹ and an impressive capacity retention of 93.6 % and coulombic efficiency of 96.8 % over 10,000 cycles at 5 A g⁻¹. This work highlights the critical role of oxygen vacancies and dual ion insertion in enhancing the performance of V₂O₅ cathodes, providing valuable insights for developing fast and stable AZIB systems.