Copper ferricyanide particles modify Prussian blue and its analogues on the surface as cathode for high-performance sodium-ion batteries

Prussian blue and its analogs are currently attracting widespread attention as cathode materials for sodium-ion batteries due to their accomplished performance and low price. However, the unavoidable disruption of the structure and the dissolution of the surface layer of the material during sodium ion de-embedding affects its stability. In this work, using a simple method, we synthesize a composite material with uniformly grown Copper Ferricyanide particles on the surface of ferric ferricyanide. The material has a high specific capacity of more than 122.57mAhg−1 at 0.2 C (1 C=100mAg−1) and an initial Coulombic efficiency of 99.9 %. It can maintain over 92 % capacity retention after 800 cycles at 1 C. It also has excellent rate performance with a specific capacity of 103.4mAg−1 at 20 C. With its simple method and low cost, this surface modification strategy is of interest in the large-scale production of cathode materials for sodium-ion batteries.