Decoration of nickel hexacyanoferrate nanocubes onto reduced graphene oxide sheets as high-performance cathode material for rechargeable aqueous zinc-ion batteries.

Prussian blue analogues (PBA) have attracted much attention in energy research due to their unique three-dimensional open framework structure, adjustable metal ions, and facile synthesis. However, the application of PBA as a cathode material for aqueous zinc-ion batteries (ZIBs) is restricted by its poor cycling performance and lower capacity. In this paper, we develop a new PBA-based hybrid cathode material for aqueous ZIBs by loading uniform nickel hexacyanoferrate (NiHCF) nanocubes onto reduced graphene oxide (RGO) sheets. In the NiHCF/RGO hybrid, NiHCF nanoparticles are well anchored on the RGO layers, forming a conductive network. The strong synergy between NiHCF and highly conductive RGO effectively increases the specific surface area, accelerates the electron and ion transport, and inhibits the structural collapse of the NiHCF/RGO electrode during the Zn insertion/extraction process. Benefiting from the above advantages, the NiHCF/RGO hybrid exhibits a remarkable reversible capacity of 94.5 mAh g at a current density of 5 mA g, excellent rate performance of 50.1 mAh g at 200 mA g, and enhanced cycling stability with a capacity retention of 80.3% after 1000 cycles at 200 mA g. This work provides a simple and effective way to improve the electrochemical performance of PBA-based cathodes for aqueous ZIBs application.