Ammonium vanadate cathodes in aqueous zinc-ion batteries: design strategies and research progress

Aqueous zinc-ion batteries (AZIBs) have attracted increasing attention as promising candidates for large-scale energy storage, owing to their high safety, environmental friendliness, and abundant zinc resources. Nevertheless, the development of high-performance AZIBs is constrained by cathode materials. Traditional cathode materials suffer from structural collapse, slow ion diffusion, and poor conductivity. In contrast, ammonium vanadates (AVOs) are being widely applied due to their unique structural advantages and higher Zn 2+ diffusion coefficients. This review focuses on the recent advancements in AVOs as high-performance cathode materials for AZIBs, analyzing the morphological variations among different AVOs and comparing their structural and electrochemical characteristics to elucidate the underlying structure-performance relationships. Moreover, key strategies to optimize their electrochemical performance are systematically discussed, such as defect engineering, interlayer spacing modulation, and composite construction with conductive materials. Finally, the review outlines current challenges and future research directions for advancing AVOs’ cathodes in practical AZIBs applications.