The synergistic effect of iron cobaltite compare to its single oxides as cathode in supercapacitor

Abstract

Mixed transition metal oxides have attracted great attention in supercapacitors applications due to their better electrochemical performance than their single oxides. In this work, iron cobaltite (FeCo2O4) and its single metal oxides i.e. iron oxide (Fe2O3) and cobalt oxide (Co3O4) were synthesized by a simple hydrothermal process. The structural, spectroscopic and morphological properties were studied using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and field-emission scanning electron microscope (FESEM). XRD and FTIR results show the composition of the products. The obtained iron oxide was α-Fe2O3. FESEM images show that FeCo2O4 and its single metal oxides exhibit different morphology even though they were synthesized via similar method. The electrochemical properties of the α-Fe2O3, Co3O4 and FeCo2O4 electrodes were examined by cyclic voltammetry (CV), galvanostatic charge/discharge (GCD) and electrochemical impedance spectroscopy (EIS) in a 6 M KOH electrolyte solution. At comparable current density, the FeCo2O4 electrode has the highest specific capacitance (Csp), followed by Co3O4 and α-Fe2O3. An asymmetric FeCo2O4/KOH/GO supercapacitor was fabricated. The supercapacitor exhibits maximum energy density of 14.5 Wh kg−1 and maximum power density of 2177 W kg−1. It demonstrates 60% rate capability after 1000 continuous charge-discharge cycles at 1 A g−1.