Preparation Of Graphene Based Supercapacitor And Study Of Their Performance

Electrochemical capacitors(ECs),also called supercapacitors(SCs),have attracted substantial attention owing to their higher power densities and long cycle life relative to secondary batteries and traditional electric double-layer capacitors.They can be used both as the primary power source and in combination with batteries or fuel cells.Supercapacitor is considered as a promising high-power source with a range of applications from portable electronics and memory backup systems to hybrid electric vehicles and aerospace.The performance of SCs depends primarily on their electrode materials,thus promoting research regarding the development of electrode materials.Some materials have been used as candidate supercapacitor electrodes including carbonaceous materials,transition metal oxides,conducting polymers,compounds and so on,However,it is known that any kind of material is incapable to exhibit all the characteristics,including high cycle life,high energy density and high power density.In this work,pristine graphene,nitrogen-doped graphene were synthesized by a facile solvothermal process.We report superior capacitance of carboxyl functionalized and surfactant-intercalated graphene prepared by a relatively simple,two-step solution-based processing technique.Both graphene and nitrogen-doped graphene coated with transition metal oxides nanoparticles were synthesized through a chemical-solution route.Scanning electron microscopy was used to characterize the morphology of the obtained graphene based films.Energy dispersive X-ray spectrometer and X-ray diffraction analyses were carried out to investigate the composition and crystal structure of the as-obtained graphene based materials.The electrochemical performance of as-obtained graphene based materials was measured using cyclic voltammetry and charge/discharge curves.Graphene-based thin films were prepared by a blade coating method and following by heat treatment under a certain temperature,and solid-state supercapacitors were fabricated employing graphene-based films and polyvinyl alcohol(PVA)-H3PO4 gel as electrodes and electrolyte,respectively.