Fabrication of polyaniline-encapsulated ammonium vanadate for high-performance aqueous zinc-ion storage

Aqueous zinc-ion batteries (AZIBs), which combine non-flammable aqueous electrolytes with low cost and environmental compatibility, hold considerable promise for grid-scale energy storage. Layered vanadium oxides stand out among the cathode candidates considered so far, since their open framework structures, high theoretical capacities, and abundant vanadium reserves are well suited to Zn 2+ storage. In practice, however, these electrodes suffer from poor electronic conductivity and progressive vanadium loss during cycling, and water at the electrode–electrolyte contact further accelerates this degradation. In this work, polyaniline (PANI) was anchored on the surface and intercalated into the interlayer galleries of ammonium vanadate (NH 4 V 4 O 10 , NVO), yielding NVO@PANI composites. The hydrophobic PANI layer shields the electrode surface from water, suppresses vanadium dissolution, and thereby extends cycle life, while the conductive polymer network simultaneously boosts electron transport and rate capability. In addition, PANI incorporation partially amorphizes the NVO lattice, generating extra pathways for Zn2 + migration and accelerating ion diffusion. The optimal NVO@PANI-50 cathode achieves 443.68 mAh g − 1 at 0.2 A g − 1 and 255.99 mAh g − 1 at 5 A g − 1 , with 93.92% of the initial capacity retained after 1000 cycles. This interfacial-engineering strategy thus provides a scalable pathway toward robust vanadium-based cathodes for AZIBs.