Graphite-zinc oxide mixture synthesized via room temperature solid state reaction as electrodes for electrochemical capacitors

Abstract

In this study, the potential of graphite-ZnO mixtures as electrode material for electrochemical capacitors (ECs) was studied. The mixture was synthesized via room temperature solid state reaction and was drop-casted onto an ITO-PET substrate to form the electrodes. These electrodes were assembled together with a PVA-H₃PO₄ electrolyte and a separator to construct ECs. The fabricated ECs were subjected to electrochemical impedance spectroscopy (EIS) and cyclic voltammetry to quantify their electrochemical properties. The obtained cyclic voltammetry curves were used to compute for the capacitance, specific capacitance, energy density, and power density of the ECs. It was found that the G-ZnO3 sample (3:1) achieved a capacitance of 90 µF, but the graphite EC had a higher specific capacitance of 6.90 mF/g as compared to the ECs with ZnO. This was attributed to the poor conductivity of ZnO and the aggregation of the graphite and zinc oxide particles resulting to the decrease in the conduction sites on the surface of the electrode.