Enhanced performance of Fe-doped manganese oxide films as supercapacitor electrodes

This paper reports enhancement in the specific capacitance of iron-doped manganese oxide ( $$\hbox {MnO}_{\mathrm {2}})$$ films, potentiostatically deposited on stainless-steel substrates. The properties of deposited films were investigated through cyclic voltammetry and galvanostatic charge/discharge characteristics. The specific capacitance, as determined through cyclic voltammetry and galvanostatic charge/discharge characteristics, respectively, was found to be 248.79 and 277.5 F $$\hbox {g}^{\mathrm {-1}}$$ for undoped films, whereas it exhibited an increase with doping and was found to be 449.61 and 487.5 F $$\hbox {g}^{\mathrm {-1}}$$ , respectively, corresponding to a dopant concentration of 4 atomic percentage. The electrochemical impedance data were fitted with a modified Randles equivalent circuit to find series resistance, charge-transfer resistance, double-layer capacitance and ion diffusion. According to electrochemical impedance spectroscopy, the enhancement of ion diffusion was found to be the major cause for enhancement in capacitive performance of the films.