An investigation of the electrochemical properties of CuCo2O4@NiCo2O4 composite as binder-free electrodes of a supercapacitor

Abstract

Metallic oxides are considered promising candidates for supercapacitors owing to their inherent pseudocapacitive behavior and superior electrochemical properties. In this work, NiCo2O4, CuCo2O4, and CuCo2O4@NiCo2O4 composite electrodes are synthesized directly on a nickel foam substrate via the facile hydrothermal method. The phase of the prepared materials was analyzed using the X-ray diffraction method. The morphology of the prepared binder-free electrodes was observed by scanning electron microscopy. The electrochemical testing was done in a 2 M KOH solution against an Ag/AgCl reference electrode. The CuCo2O4@NiCo2O4 composite electrode demonstrated a value of specific capacitance as high as 422 F g-1 at a current density of 1 A g-1 and thus outperformed the NiCo2O4 and CuCo2O4 in terms of its electrochemical performance. The CuCo2O4@NiCo2O4 composite retained a specific capacitance of 278 F g-1 even with the increase of current density to 10 A g-1, which corresponds to a 34% loss of capacitance compared to 40% and 48% of individual NiCo2O4 and CuCo2O4 electrodes, respectively. Hence, the synergy in a composite material demonstrates it to be a potential candidate as an electrode in supercapacitors.