Capacitive Behavior of Manganese Dioxide/Stainless Steel Electrodes at Different Deposition Currents

Amorphous manganese dioxide thin films were prepared by galvanostatic cathodic deposition at current densities of 0.5-1 mA/cm 2 on etched stainless-steel substrate from 20 mM KMnO4 solution. The structure of the deposited oxides was investigated using X-ray diffraction analysis. The capacitive behavior of the manganese dioxide electrodes was characterized by cyclic voltammetry and electrochemical impedance spectroscopy in 0.5 M Na2SO4 electrolyte. The capacitive performance was found to increase with the increase in the deposition current density. The electrode deposited at current density of 1 mA/cm 2 showed specific capacitance of 174 F/g at a scan rate of 10 mV/s, equivalent series resistance of 3.53 Ω, and charge transfer resistance of 1.39 Ω. The improvement in the capacitive behavior of the electrode with the increase in the deposition current density was attributed to the increase in the electronic properties of the deposited oxides.