Characterization of MnO2 and AgNWs Co-Doped into an Activated Carbon Thin Film Electrode for Supercapacitors

Abstract

In this study, the properties of supercapacitors were improved by doping nanomaterials. Transition metal oxides (i.e., MnO2) with Faraday’s reduction-oxidation (redox) reaction and silver nanowires (AgNWs) with high conductivity were doped into activated carbon based material to prepare thin-film electrodes. The results indicated that doping with AgNWs can effectively improve the conductivity of the thin film electrode. A conductive network was constructed between activated carbon and MnO2, and the optimal balance between conductivity and specific surface area was achieved through suitable doping. Thus, the electrochemical efficacy of the developed supercapacitor was effectively improved, and its specific capacitance increased from 240.14 F/g before doping to 1020.91 F/g (by 3.25 times) after doping. In addition, the prepared thin-film electrodes had favorable reproducibility at different voltage scan rates. Electrochemical impedance spectroscopy indicated a noticeable decrease in the charge transfer resistance of the thin-film electrodes from 1.46 Ω before doping to 0.66 Ω after doping. The doping of the two nanomaterials preserved their respective advantages and created a synergistic effect. The doping of transition metal oxides with metal AgNWs has applications in thin-film preparation for different types of supercapacitors, thereby enhancing the capacitance effect.