Preparation And Electrochemical Performance Of Nano-ZnO/Graphene Composite Structure

With the popularity of electronic equipment,people's demand for energy storage equipment is increasing day by day.Supercapacitor with advantages that short charging and discharging time,long cycle life and high energy density,attracts widespread attention.Among the supercapacitor electrode materials,graphene has excellent conductive ability and good rate performance,zinc oxide(ZnO)has high specific capacitance and poor conductive ability,this paper combines graphene and ZnO together to get nano-ZnO/graphene composite structure,which has high specific capacitance and good rate performance.The main research contents of this paper are as follows:1)The preparation of graphene oxide(GO).In order to get nano-ZnO/graphene composite structure,graphene oxide is prepared firstly,that the surface of graphene with some oxygen-containing functional groups,which provides positions for ZnO synthesis.In this paper,modified Hummers method based on oxidation-reduction method was used to prepare graphene oxide.2)The synthesis of nano-ZnO/graphene composite structure.Using the prepared GO as a substrate,zinc oxide is grown in situ on the surface by Hydrothermal method,and the graphene oxide was reduced to graphene.The composite structure of nano-ZnO/graphene was obtained.Zinc oxide is prepared using zinc acetylacetonate or zinc nitrate.And using DMF or deionized water as solvent.The prepared nano-ZnO/graphene composite structure is characterized by electron scanning microscopy.3)Using the prepared nano-ZnO/graphene composite structure to prepare a supercapacitor electrode.The negative electrode of the supercapacitor was prepared by coating nano-ZnO/graphene composite structure,current collector,conductive agent and binder.4)Studying the electrochemical performance of nanometer zinc oxide / graphene composite electrode.The electrochemical test of the prepared negative electrode was carried out using the three-electrode test system and the electrochemical workstation.Mainly test the electrode's cyclic voltammogram,constant current charge–discharge curves,cycle life and rate performance.The nano-ZnO/graphene composite structure prepared in this paper has a larger specific capacitance than graphene,better rate performance and longer cycle life than ZnO.When the composite structure has high content of graphene,it achieves better rate performance.With the decrease of graphene and the increase of Zn O,the specific capacitance of the composite structure increases,the rate performance decreases.The maximum specific capacitance of the composite structure reaches 734F/g.