High-efficiency freeze-dried ultrathin V2O5 nanosheet arrays on reduced graphene oxide as aqueous Zn-ion battery cathode

Abstract

The aqueous rechargeable zinc-ion batteries (ZIBs) are a potential grid-scale energy storage device because of the high security, economy and high performance. There is a need for developing ZIBs cathode materials with high specific energies. Herein, novel ultrathin V2O5 nanosheet arrays deposited on reduced graphene oxide (V2O5/rGO) are prepared via freeze-drying technique in combination with a scalable in-situ thermal decomposition-reduction method for ZIBs cathode. The introduction of rGO not only enhances electrical conductivity and provides exceptional structural stability for V2O5/rGO, but also increase the electrode hydrophobicity, effectively inhibiting the dissolution of vanadium. As a result, the assembled ZIBs demonstrate a high capacity of 438.5 mAh/g at 0.1 A/g, a capacity of 278.2 mAh/g after 1000 cycles at 2 A/g, with an 85.6 % capacity retention. This work provides a simple and scalable strategy to prepare graphene-based nanocomposites.