Vanadium Oxide–Modified Cathodes for Aqueous Zinc-Ion Batteries: A Review

Aqueous zinc-ion batteries (AZIBs) are gaining traction as a safe, low‑cost alternative to lithium‑based systems, not least because of their high ionic conductivity. Among the candidate cathode materials, vanadium oxides stand out for their layered/open frameworks, multiple valence states, and high theoretical capacities—V₂O₅ in particular offers a combination of facile synthesis and a two‑electron redox chemistry that gives a respectable 589 mAh·g⁻¹. In practice, though, its poor electronic conductivity, sluggish Zn²⁺ diffusion, structural degradation upon repeated cycling, and active‑material dissolution remain serious bottlenecks. This review summarizes the four main classes of AZIB cathodes and the three prevailing energy‑storage mechanisms, then focuses on recent modification strategies for V₂O₅—namely, preparation routes, Li⁺‑storage/deintercalation behavior, morphology engineering, and conductive composite design—and discusses how each strategy improves electrochemical performance. Despite these advances, long‑term structural stability and rate capability at high current densities still fall short of practical requirements. The aim here is to offer a reference for developing better vanadium‑based cathodes in the future.