Hollow NiF2/CoF2 cubes as electrode materials for high-performance supercapacitors

Abstract

In this paper, NiF2/CoF2 composites with hollow cubic structures were fabricated with Ni–Co Prussian blue analogue (PBA) as a template, which were characterized by using XRD, SEM, TEM, XPS and EDS mapping. Electrochemical properties of obtained samples were investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge-discharge tests. Results show that the hollow NiF2/CoF2 cubes possess commendable specific capacitance of 1491.1 F/g at the current density of 1A/g. Meanwhile, they deliver excellent rate capability (77.2% capacity retention from 1 to 10 A/g) and remarkable cycling stability with 78.7% specific capacitance retention after 3000 cycles at 5 A/g. The superior electrochemical performance can be attributed to the unique hollow cubic structure and the coupling of nickel and cobalt. This work indicates that NiF2/CoF2 composites can be a promising electrode material for the high-performance supercapacitor.