V2O3@C Microspheres as the High-Performance Cathode Materials for Advanced Aqueous Zinc-Ion Storage

Vanadium oxides attract increasing research interests for constructing the cathode of aqueous zinc-ion batteries (ZIBs) because of high theoretical capacity, but the low intrinsic conductivity and unstable phase changes during the charge/discharge process pose great challenges for their adoption. In this work, V2O3@C microspheres were developed to achieve enhanced conductivity and improved stability of phase changes. Compounding vanadium oxides and conductive carbon through the in-situ carbonization led to significant improvement of the cathode materials. ZIBs prepared with V2O3@C cathodes produce a specific capacity of 420 mA h g-1 at 0.2 A g-1. A reversible capacity of 132 mA h g-1 was achieved at 21.0 A g-1. After 2000 cycles, the electrode could still deliver a capacity of 202 mA h g-1 at the current of 5.0 A g-1. Besides, the energy density of batteries constructed with the thus-prepared electrodes was about 294 W h kg-1 at 148 W kg-1 power. The in-situ compounding of V2O3 and carbon resulted in a microstructure that facilitated the stable phase transformation of ZnxV2O5-a·nH2O (ZnVOH), which provided more Zn2+ storage activity than the original phase before electrochemical activation. Moreover, the in-situ compositing strategy presents a simple route to the development of ZIB cathodes with promising performance.