Enhancement of Vanadium-Based Cathodes for Aqueous Zinc-Ion Batteries via Silver Modification

Vanadium-based oxides are promising cathodes for aqueous zinc-ion batteries (AZIBs) but suffer from structural instability and dissolution. To address this, silver (Ag)-modified VO₂ (AgVO) composites were synthesized via a one-step hydrothermal method. The effects of AgNO₃ precursor amount and hydrothermal temperature on the material's properties were systematically investigated. Characterization confirmed effective Ag incorporation primarily as metallic nanoparticles, which induced a significant morphological transformation from a randomly distributed rod-like structure to a nanofiber bundle architecture. Electrochemical tests demonstrated that the optimized AgVO cathode exhibits significantly enhanced performance compared to the pristine VO₂, including high-rate capability and excellent cycling stability. At a high current density of 3 A g⁻¹, the cathode delivered an initial discharge capacity of 220.1 mAh g⁻¹ and retained a capacity of 140.5 mAh g⁻¹ after 500 cycles, corresponding to a notable retention of 63.8% and a high average Coulombic efficiency close to 100%. Postcycling characterization further revealed the role of Ag in stabilizing the structure. This work confirms that Ag modification is an effective strategy for enhancing the structural stability and electrochemical properties of vanadium-based cathode materials for advanced AZIBs.