Synthesis And Electrochemical Performance Of Three-dimensional Graphene And Cobalt Hydroxide Electrode Materials

In this thesis, the three-dimensional(3D) graphene with few defects, high quality and lowly density was synthesized by atmospheric pressure chemical vapor deposition(APCVD) on nickle-foam. The 3D graphene with density of 0.3252 mg/cm2 achieved a maximum double-layer specific capacitance of 75.6 F/g at a current density of 0.4 A/g. The 3D graphene/Nickel-foam have been used as substrates for cathodic electrodeposition of cobalt hydroxide. The obtained 3D graphene/Cobalt hydroxide nanocomposite exhibited an excellent pseudocapacitive behavior with specific capacitance up to 1260 F/g at a current density of 1 A/g and a good cycling stability with about 91.47% capacitance retention after 25000 cycles at a current density of 40 A/g. A novel asymmetric supercapacitor was designed and assembled by this 3D graphene/Cobalt hydroxide as the positive materials and 3D graphene/active carbon(AC) as the negative material in 1 M KOH aqueous electrolyte. The energy density of 15.96 Wh/kg was achieved at power density of 1200 W/kg. That will possess great potential for applications in developing a novel type supercapacitor with a high energy density and power density.