In-site pulse electrodeposition of manganese dioxide/reduced graphene oxide nanocomposite for high-energy supercapacitors

Manganese dioxide/reduced graphene oxide (MnO2/RGO) nanocomposite material was synthesized by the insitu anodic pulse electrodeposition method to fabricate symmetric supercapacitors. The effects of the pH value of the electrodeposition bath were considered on the properties of fabricated electrodes. Three pH values of 4, 7, and 10 were evaluated, and physicochemical properties were studied using field-emission scanning and transmission electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, nitrogen gas sorption isotherm, and thermogravimetric analysis. The electrochemical evaluation was performed by galvanostatic charge/discharge (GCD), cyclic voltammetry (CV), and electrochemical impedance spectroscopy techniques. The results revealed that the MnO2/RGO nanocomposite prepared at pH = 7 (i.e., MGO7) exhibited a maximum specific capacitance of 693.4 F g(-1) at a current density of 0.5 A g(-1). The symmetric supercapacitor based on MGO7 was also assessed using GCD and CV tests. Its specific capacitances at current densities of 0.5 and 20 A g(-1) were 577.9 and 290.0 F g(-1), respectively. The symmetric supercapacitor maintained 79.2% of initial capacitance after 5000 consecutive charge/discharge cycles at a current density of 4 A g(-1). The highest energy density of 80.3 Wh kg(-1) at the power density of 0.625 kW kg(-1) and the highest power density of 25 kW kg(-1) at the energy density of 40.3 Wh kg(-1) was achieved by the fabricated supercapacitor.

Automated summary

Manganese dioxide/reduced graphene oxide (MnO2/RGO) nanocomposite material was synthesized using anodic pulse electrodeposition method, and the effects of different pH values on electrode properties were studied through various physicochemical analyses. The fabricated symmetric supercapacitor demonstrated high specific capacitance, maintaining good performance even after 5000 charge/discharge cycles.