| Since the beginning of the Industrial Revolution,human society has developed rapidly,the world's population is increasing and the demand for energy is increasing,resulting in a shortage of fossil energy.People have begun to develop new energy sources and become new trends,such as solar energy,wind energy,nuclear energy,biomass energy.At the same time,in order to achieve the requirements of sustainable economic and environmental development,the solution of how to use energy more effectively is imminent,thus promoting the research of energy storage/conversion devices.As a new type of green energy storage device that can quickly store and release energy,supercapacitors are widely used in the fields of public transportation,electronics and aerospace.The electrode is the core component of the super capacitor,and the influence of the electrode material on the electrode is very important.This article mainly introduces graphene with large specific surface area and good electronic conductivity into manganese dioxide with high energy density but poor conductivity to prepare composite materials,so that it has more excellent properties to prepare electrode materials.The electrode material is assembled into a symmetrical supercapacitor,and its electrochemical performance is studied using an electrochemical workstation.The content of this paper is as follows:1.Graphene with higher yield and better electrochemical performance was prepared by chemical vapor deposition(CVD)method based on laboratory-made magnesium oxide as the substrate.By fixing the gas velocity of methane and nitrogen,the effects of different growth temperatures and growth times on the electrochemical performance of the prepared graphene were investigated.The morphology and structure were characterized by scanning electron microscope,micro confocal laser Raman spectrometer,N2 adsorption and desorption instrument,etc.The results show that under the conditions of a growth temperature of 950?,a growth time of 8 min,the graphene produced has a higher yield,a larger specific surface area,but a higher Defects,prepare them as electrode materials.The electrode sheet is assembled into a symmetric super capacitor in a super purification glove box.Electrochemical workstation tests its electrochemical performance.The test results show that the graphene electrode material prepared under these conditions shows the best capacitance performance in supercapacitors,and has good reversibility and electric double layer capacitance characteristics.With a current density of 1 A/g,its specific capacitance is 129.7 F/g.2.Using the graphene prepared above,a nano-MnO2/graphene composite material is prepared by a hydrothermal method,and the synergistic effect of them is used to prepare a more excellent electrode material.The effects of different hydrothermal temperature,hydrothermal reaction time,manganese source ratio and composite mass ratio on the electrochemical performance of the prepared composite material were investigated.It was characterized by scanning electron microscope,X-ray photoelectron spectroscopy,etc.The results show that when the hydrothermal temperature is 120?,the hydrothermal time is 12 h,the manganese source ratio is 3:1,and the composite mass ratio is 25%,the prepared nano-flower-like MnO2/graphene composite material has the best electrochemistry performance.It was prepared as the electrode material of supercapacitor,and assembled into supercapacitor for performance test with electrochemical workstation.The test results show that the composite material prepared under the above conditions has good reversibility and capacitance characteristics.Its specific capacitance is 263.2 F/g at a current density of 0.5 A/g. |
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