Development of High-performance Supercapacitors Based on MnO2/Functionalized Graphene Nanocomposites

In this report, MnO2 nanoparticle-deposited functionalized graphene sheets were prepared and their superior electrochemical performances were demonstrated by cyclic voltammetry, galvanostatic charge-discharge, and impedance analysis. Ionic liquids were employed to functionalize the surface of reduced graphene oxides (RGOs), leading to prevention of the aggregation of RGO sheets and abundant growth sites for deposition of MnO2 nanoparticles. As-prepared MnO2/RGO nanocomposites were characterized using scanning electron microscope, transition electron microscope, X-ray photoelectron spectroscopy, and X-ray diffraction. Electrochemical properties of MnO2/RGO electrode were evaluated using Na2SO4 electrolyte under a three-electrode system. The MnO2/RGO electrode showed a high specific capacitance (251 F/g), a high rate capability (80.5% retention), and long-term stability (93.6% retention).