Porous V2O5 yolk–shell microspheres for zinc ion battery cathodes: activation responsible for enhanced capacity and rate performance†
Rechargeable aqueous zinc ion batteries have attracted significant attention for practical energy storage due to their low cost and high safety, however, it is still a hard task to find suitable cathode materials to meet the demand of both high capacity and rate performance. Here, we propose a high-performance anhydrous V2O5 yolk–shell cathode via a facile template-free solvothermal technique. Owing to its porous structure, the V2O5 cathode could largely facilitate rapid electrolyte transportation and restrain structural collapse during cycling. Moreover, it is interesting to find that the interlayer spacing expands from 4.37 to 13.45 Å through an interesting activation process, as a result, the prepared V2O5 cathode demonstrated high reversible capacities of 410 mA h g−1 at 0.1 A g−1 and 182 mA h g−1 at 20 A g−1 and a capacity retention of 80% can be achieved over 1000 cycles at 5.0 A g−1, which is superior to those of most commonly reported anhydrous V2O5 cathodes. Therefore, this paper demonstrates the potential of V2O5 for achieving high energy/power densities as a cathode material in ZIBs.