Carbon-coated Vanadium Oxide Nanoflowers with K+ Ions Pre-embedment as a High-rate Cathode for Zinc-Ion Batteries

Recently, aqueous zinc-ion batteries have become a promising candidate for energy storage devices due to their low cost, high capacity, and environmental friendliness. However, the low electrical conductivity and irreversible Zn2+ intercalation/extraction of cathode materials limit the rate performance and cycling stability of Zn-ion batteries. Herein, carbon-coated V2O5 nanoflowers with K+ pre-embedment (KVO-C) were synthesized by hydrothermal and high-temperature annealing methods, showing enhanced electrical conductivity and crystallinity. Assembled with Zn anode and 2 M Zn(CF3SO3)(2) electrolyte, the optimized KVO-C3 battery achieves a high specific capacity of 389.2 mAh g(-1) at a current density of 0.1 A g(-1) and retains 85% even with a 50-fold increase in current density and cycling back to 0.1 A g(-1). KVO-C3 also shows excellent capacity retention of 77% and coulomb efficiency of nearly 100% after 2000 cycles and delivers a high energy density of 209 Wh kg(-1) at a power density of 3500 W kg(-1).