Three-dimensional mixed-valence polyoxovanadates@polyaniline architecture towards high-performance rechargeable aqueous zinc-ion batteries cathode

Aqueous zinc ion batteries (AZIBs) are toward promising candidates of energy storage systems for their low cost, high safety and eco-friendliness, whereas the sluggish reaction kinetics and unstable internal structure of cathode materials greatly limited the practical application of AZIBs. Herein, we employ the three-dimensional mixed-valance polyoxovanadates [Co3(H2O)12][VIV10VV8O42(SO4)]·24H2O (CoVO) coated with polyaniline (PANI) as stable zinc ion storage material (denoted as CoVO@PANI). The 3D highly porous CoVO framework constructs multidimensional interconnected Zn2+ migration channels, and the high conductivity of PANI facilitates the formation of oxygen defects during in-situ polymerization process and inhibits the polyoxovanadates dissolution. Density functional theory calculation reveals that PANI significantly regulates the electronic property of the CoVO host, further promoting the electron/ion transfer kinetics and thus contributing to high-effciency Zn2+ storage performance. As expected, the optimized as-fabricated CoVO@PANI60 cathode exhibits a high reversible capacity of 456.8 mAh g−1 at 0.1 A g−1 and long-term cyclability with capacity retention of 90.4 % after 1500 cycles at 10 A g−1.