Facing the capacity fading of vanadium-based zinc-ion batteries

The complicated interactions between inserted ions and host lattice and the attacking action of active free water on fragile structure are the culprits of the serious capacity fading of vanadium (V)-based aqueous zinc–ion batteries (AZIBs).To achieve the breakthrough of stable V-based AZIBs, more endeavors should be exerted on pH regulation, separator optimization, pseudocapacitive-controlled cathode design, and development of advanced in situ characterization techniques.The comparison protocol of V-based AZIBs should consider the cumulative capacity, Coulombic efficiency, and the ratio of actual capacity to theoretical capacity.