Construction of Hierarchical Flower‐Shaped (NH4)2V3O8/rGO with Enhanced Zinc Storage Performance

Abstract

Vanadium-based cathode materials are being widely investigated in aqueous zinc-ion batteries (ZIBs) due to their high specific capacity. However, poor cycling stability and low conductivity limit their practical applications. Herein, the hierarchical flower-shaped (NH4)2V3O8/reduced graphene oxide (denoted as NVO/rGO) composite is designed to harvest high-efficiency Zn storage. Benefiting from the stable layered structure of NVO, the prominent pseudocapacitance, and excellent conductivity of rGO, the NVO/rGO composite exhibits a high specific capacity of 375.3 mAh g−1 at 0.2 A g−1, excellent cycling stability of 265.0 mAh g−1 after 3700 cycles at 5.0 A g−1 (capacity retention over 95.3 %), and outstanding rate performance of 263.9 mAh g−1 at 10.0 A g−1 by using traditional coin cells. To further verify the practicability of the NVO/rGO cathode, flexible electrode and xanthan gum electrolyte are adopted to assemble quasi-solid-state ZIBs, which exhibit a great specific capacity of 185.0 mAh g−1 at 0.5 A g−1 and good stability under different bending angles with an impressive capacity retention of 92.2 % after cycling. This study illustrates that hierarchical flower-shaped NVO/rGO has a promising potential as aqueous or quasi-solid-state ZIBs cathode and improves the application of vanadium-based materials.