Preparation And Supercapacitor Properties Of Graphene-based Composite

Supercapacitor is a new type energy storage device with a lot of attractive properties including high power density, fast charge and discharge, long cycle life, good safety and pollution-free. Supercapactiors have huge potential applications in electric devices, bridging the traditional capacitor and battery. In the purpose of improving the electrochemical performance of the supercapacitor, graphene-based/metal compound (such as MnO2, ZnO and MOF) supercapacitor electrode material are synthesized in which capacitor performance is improved by increasing the surface area and the conductivity of the electrode material. The structure of the electrode and the electrochemical performance are also studied.(1) Graphene oxide(GO)/needle-like MnO2 composite is synthesized in which GO and MnSO4 as the precusors, Hydrazine hydrate, sodium borohydride, Vc and hydrothermal as the reducing agents, respectively. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis show that the change in morphology and phase has been occurred in hydrazine hydrate and sodium borohydride system, which the needle-like MnO2 has become the Mn3O4 nanoparticles. Furthermore, the electrode in hydrazine hydrate shows the highest specific capacitance of 324.9F/g. In addition, the effect of the reduction time have also been explored, the result indicates that keeps the reduction time for 12h would be best for the specific capacitance.(2) Fuctional GO (f-GO)/Zinc oxide (ZnO) quantum dots composite is developed with the previously synthesis of ZnO and f-GO. The results show that the ZnO anchores on the f-GO with the Zn-S bond, and when the volume of the ZnO is 100ml, it possession the highest specific capacitance of 149.4F/g.(3) The GO/MOF composite is synthesized by a hydrothermal process in which keeping the GO in different content. The results show that it exhibits a mass specific capacitance of 141.3F/g when the GO is added in an amount of 5.