Trace interstitial water removal from copper-cobalt Prussian analogues by rGO coating for high performance sodium ion supercapacitor devices

Reduced Graphene oxide coating is applied to CuCoHCF material to remove interstitial water at mild reaction environment, and the conductivity is increased without damage of crystal structure. Superior electrochemical performance is observed from the capacitor devices with electrodes made from this material, which is attributed to the decrease in space resistance resulting from intact crystal structure. The specific capacity of 120.2 F g −1 , energy density of 86.5 Wh kg −1 and power density of 4.3 kW kg −1 is achieved on Cu 0.66 Co 0.33 HCF@rGO//AC device. The specific capacity is 98% of starting value after 2000 cycles.