MnO2/CoO electrode for supercapacitor: Synthesis and electrochemical performance

Abstract

In this work, Cobalt Oxide (CoO) was prepared by co-precipitation method by taking 1:3M of Co (NO3)2·6H2O and NaOH. Synthesis of Manganese dioxide (MnO2) was done by reduction of potassium permanganate (KMnO4) with aqueous sulphuric acid (H2SO4) by hydrothermal process. For making the coin cell capacitor CoO and MnO2 were spin-coated on the thin copper sheet which was used as the current collector, PEDOT: PSS poly (3,4 – ethylene dioxythiophene) as electrolyte and cellulose paper as a separator. Scanning electron microscopy (SEM) analysis has been employed to study surface morphology and to confirm the formation of nanoparticles. An image analysis approach using ImageJ has been used to measure the percentage of porosity from the SEM micrographs. The parameters like specific capacitance, energy density, and power density were calculated from the CV measurements and were compared. When both electrodes are MnO2, it has a specific capacitance of 33.57F/g, the energy density of 16.84 J/g, and power density of 4.21 W/g and when both electrodes are CoO it has a specific capacitance of 29.19F/g, the energy density of 14.59 J/g and power density of 3.65 W/g. But one side with MnO2 and the other side with CoO electrode shows a specific capacitance of 44.92F/g, an energy density of 22.46 J/g, and a power density of 5.62 W/g.