Study On Preparation And Eletrochemical Perfomance Of Nitrogen Doped Carbon/Ni?OH?₂/MnO₂ Composite

Over the past decade,renewable and clean energy,such as solar energy,water energy and wind power,has attracted considerable social attention because of environmental problems and resource depletion caused by the excessive use of fossil fuels.Due to the restriction of the geographical environment,the output energy of the renewable energy is unstable.To solve these problems,energy storage devices have become the focus of research.The supercapacitors,with their rapid charging and discharge,high energy density and power density,have attracted the great interest of scholars.Currently,the materials of supercapacitors are mainly carbon-based materials,conductive polymer materials and transition metal oxides or hydroxides.However,during the course of the research,scholars found that the single material has its own defect limitation.But through combination of different types of materials,it will effectively enhance the overall performance of the super capacitor.Therefore,in this project,we explore the overall improvement of the performance of the supercapacitor by using the framework structure of the carbon-based material and the deposition of the transition metal oxide and the hydroxide.For the framework structure of carbon-based materials,we first prepared nitrogen-doped carbon(nitrogen-doped graphene/nitrogen-doped carbon nanotubes)by thermal cracking with nickel foam as a catalyst.The nitrogen-doped carbon were characterized by SEM,XRD,Raman and XPS.The best preparation method was determined: the mass ratio of glucose to dicyandiamide was 1:30,the mass ratio of the two to the foam nickel was 5:1,and pyrolysis reaction was carried out at 800 ? for 1 h.And the prepared nitrogen-doped carbon has a uniform and stable structure,which relatively increases the specific surface area of the framework the electrical conductivity.Through different characterization and electrochemical performance tests,the best method for preparing nitrogen-doped carbon/nickel hydroxide composites is that the nitrogen-doped carbon was placed in 0.6 mol/L nickel sulfate and the reaction was carried out at 45 ? for 4 h.The electrode material prepared by this method has the highest specific capacitance,reaching 1930 F/g at a current density of 1 A/g because of the advantages of nitrogen-doped carbon structures and the performance advantages of complexing prepared nickel hydroxides.In the stability test,after 300 cycles,its specific capacitance maintained 64 % of the initial capacity at 10 A/g.Through different characterization and electrochemical performance tests,the best method to prepare nitrogen-doped carbon/nickel hydroxide/manganese dioxide composite is that the previously prepared nitrogen-doped carbon/nickel hydroxide composite was placed in deionized water,added 0.01 g potassium permanganate;transferred to a 50 m L hydrothermal reactor,had reaction at 120 ? for 6 h.The electrode material prepared by this method has the highest specific capacitance and achieves 1563 F/g at a current density of 1 A/g.In the stability test,after 1000 cycles,its specific capacitance maintained 80 % of the initial capacity at 10A/g because of the attachment of manganese dioxide and the incorporation of manganese.