Research On The Key Technology Of Hybrid Supercapacitor Based On MnO₂

Supercapacitor is a kind of energy storage device between capacitor and battery,which has high energy density and good cycle characteristics.Manganese dioxide,as the electrode material of supercapacitor,has the advantages of high energy density,low cost,environmental friendliness and wide sources,and has a very broad application prospect in the field of supercapacitor.However,the low conductivity and unstable structure of MnO₂ seriously hinder the wide application of MnO₂ in supercapacitors.In this paper,the electrochemical performance of MnO₂ composite materials will be improved by the way of composite of MnO₂ and other materials.In this paper,Vanadium disulfide was prepared by hydrothermal method,graphene oxide prepared by improved hummer method and manganese dioxide prepared by liquid precipitation method.The electrochemical properties of VS₂/MnO₂,GO/MnO₂ and GO/VS₂/MnO₂ ternary composites were studied.XRD,SEM and other analytical methods were used to analyze and characterize the composite materials.At the same time,the effects of molding pressure,adhesive and the quality ratio of composite materials on the electrode performance were studied.The composite electrode and activated carbon were used to form a hybrid supercapacitor.The electrochemical performance of the supercapacitor was studied and analyzed.The following conclusions were drawn:1.For the VS₂/MnO₂ composite prepared by liquid phase precipitation,the nano flake VS₂ is embedded between the MnO₂ particles,which improves the specific surface area of the composite,reduces the AC equivalent impedance,and improves the agglomeration of the pseudo capacitor material MnO₂.When the mass ratio of VS₂ is30wt%,and the current density is 0.25A/g,the specific capacity is 216.5F/g,and the equivalent AC impedance is 1.74?.After 1000 times of 1A/g constant current charging and discharging,the specific capacity retention rate is 84.3%.The assembled capacitor has high power density and energy density.Its value is 1700W/kg and 14.9Wh/kg.At the current density of 1A/g,the cycle charge and discharge is 1000 cycles,and the specific capacity retention rate is 84.1%.2.The specific capacity of GO/MnO₂ composite prepared by liquid precipitation method is 234.5F/g at the current density of 0.25A/g and the equivalent AC impedance is 2.31?.After 1000 times of 1A/g constant current charging and discharging,the specific capacity retention rate is 86.7%.GO/VS₂/MnO₂ ternary composite prepared by liquid precipitation method.The ratio of GO,VS₂ and MnO₂ is 1:3:6.At the current density of 0.25A/g,the specific capacity is 292.7F/g,and the equivalent AC impedance is 1.12?.After 1000 times of 1A/g constant current charging and discharging,the specific capacity retention rate is 87.5%.The combination of GO and VS₂ with MnO₂increases the contact area between the composite and the electrolyte.At the same time,due to the good conductivity of GO and VS₂,the ion diffusion transmission channel is provided,and the electrochemical performance of MnO₂ composite electrode material is improved.The assembled capacitor has high power density and energy density,its values are 1700W/kg and 17.8Wh/kg,and the specific capacity retention rate of hybrid super capacitor is 87.4%when the current density is 1A/g and the cycle charge discharge is 1000 cycles.It has higher energy density than carbon based supercapacitor.