| Supercapacitors, also named electrochemical capacitors, have been widely used in many fields to meet the requirement of energy storage device market because of their high power density, high energy density and long lifetime. The manganese dioxide (MnO2) has many advantages such as low cost, good environmental benefits and high specific capacitance. However, the large inner resistance of the MnO2itself has remarkable effect on the integral capability of electrode material. In this study, the modified Hummer’s method is used to prepare graphene oxide (GO), microwave-assisted method is explored to synthesize MnO2deposited directly on the surface of GO, and the pure MnO2material is prepared by the same steps. Then the samples are put into an oven to anneal at460℃to obtain different phases of MnO2. XRD, SEM, TEM, FTIR, Raman and other instrumental analysis are measured to investigate the morphology, structure and characteristic of the products. Then the as-prepared materials are assembled as the half-cell electrodes for their electrochemical properties by cyclic voltammetry and galvanostatic charging-discharging measurements. The specific capacitance of amorphous GO/MnO2and pure MnO2are127F/g and50F/g at the current density of100mA/g, respectively. After the annealing process, the product is crystal a-MnO2, and the specific capacitance of GO/MnO2and pure MnO2are43F/g and29F/g, respectively. It shows that the presence of GO network in the MnO? significantly improved the electrical conductivity of the composite by the formation and of conducting network and increased the reactivity of MnO2The microwave-assisted heating method is a perfect approach to prepare GO/MnO2composites as the electrodes for supercapacitors. The synthesis route has some advantages, such as simple, low energy consumption, high yield and time saving. The rapid and internal heating process has provided a remarkable efficiency to large-scale synthesis of carbon materials and their composites. |
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