Co-precipitation synthesis of nickel cobalt hexacyanoferrate for binder-free high-performance supercapacitor electrodes

Prussian blue analogue with a typical metal-organic framework has been widely used as an electrode material in supercapacitor . In this work, nickel cobalt hexacyanoferrate (Ni 2 CoHCF) was grown on nickel foam directly using a simple co-precipitation method. The as-prepared Ni 2 CoHCF was tested by transmission electron microscope, scanning electron microscope , X-ray diffraction and X-ray electron energy spectrum. The results showed that Ni 2 CoHCF has a unique open face-centered cubic structure. The Ni 2 CoHCF was used to set an asymmetric supercapacitor directly. A series of electrochemical tests showed that Ni 2 CoHCF had an excellent electrochemical performance. The specific capacitance of the supercapacitor was 585 C g −1 (1300.0 F g −1 , 162.5 mAh g −1 ) at the current density of 0.5 A g −1 . After 2000 cycles, it still maintained 85.57% of its initial specific capacitance at the current density of 10 A g −1 . The energy density was 30.59 Wh kg −1 at the power density of 378.7 W kg −1 . The results show that the supercapacitor constructed by Ni 2 CoHCF as an electrode material has high-current charge-discharge capacity, high energy density and long cycle life.