Long cycle life and high rate aqueous zinc-ion batteries enabled by polypyrrole bridging ammonium vanadium bronze nanosheet cathodes

Abstract

Aqueous zinc-ion batteries are considered promising large grid energy storage systems because of their low cost and high safety. However, the limited cycle life associated capacity fading in cathode materials, especially at high charge-discharge rates, hampers the practical applications of aqueous zinc-ion batteries. Here we report that ammonium vanadium bronze nanosheets bridged by polypyrrole (NVO@PPy) as cathodes significantly enhance the cycle life and rate performances of aqueous zinc-ion batteries. At a high charge-discharge rate of 28 C (10 A g−1), the discharge capacity gradually increases with the number of cycles and reaches the maximum value of 195 mAh g−1 over 290 cycles, and the reversible capacity maintains 58% (108.8 mAh g−1) even after 2000 cycles. The fast charging-discharging and stable cycling performances are attributed to the high electronic/ionic conductivity of NVO@PPy and the stabilizing effect of PPy on interlayer ammonium. The zinc ion storage mechanism of the NVO@PPy is jointly contributed by intercalation/deintercalation and pseudocapacitance behaviour, the latter not only provides extra capacity but also facilitates fast charge-discharge capability.