Reversible V3+/V5+ double redox in lithium vanadium oxide cathode for zinc storage

Zn ion batteries show great potential for large-scale energy storage owing to their low-cost, safe and environment-friendly features. There is an urgent need for cathode material with high-energy-density and long-service-life. Vanadium-based cathodes would be particularly desirable due to the bi-electronic transfer reaction (V5+/V4+ / V3+). Herein, we present a reversible V3+/V5+ double redox in lithium vanadium oxide (LiV3O8) with the insertion of Zn2+ for ZIBs. In this way, six-electron transition in LiV3O8 was achieved with only 7.64% volumetric expansion, yielding the highest capacity of 557.5 mA h g(-1), and good cycling retention of 85% over 4000 cycles. The use of V3+/V5+ double redox will open-up new opportunities for designing vanadium-rich cathodes for high-performance Zn ion battery.