Preparation And Electrochemical Performance Of Manganese Dioxide And Its Composite Structur

Among the many metal oxides,manganese dioxide（MnO₂）is the most promising material for supercapacitors,which has the advantages of high theoretical specific capacitance（1370 F/g）low cost,low toxicity,abundant reserves and environmental safety,etc.However,pure MnO₂as an electrode material has disadvantages such as structural instability and poor electrical conductivity,and the capacity decays extremely fast during cycling.So we often combine MnO₂material with carbon material and metal organic framework to improve the conductivity of the material and improve its electrochemical performance.In view of the above points,this paper focuses on the following two aspects of research.1.Manganese dioxide nanograss is grown on porous carbon cloth by hydrothermal method（MnO₂//p CC）.The metal-organic skeleton of nickel（Ni）MOF is then uniformly covered with manganese dioxide nanograss by a second hydrothermal step.Composites of MnO₂,（Ni）MOF with large surface area and abundant microporosity were prepared,and composites with different morphologies were obtained by adjusting the hydrothermal reaction time.It was found that when the hydrothermal time was 3h,the capacity reached 376 F/g at a current density of 1 A/g and exhibited good electrochemical performance with a capacitance retention of 93.4%after 5000 cycles.2.Biomass carbon（CPs）,carbon nanotubes（CNTs）and carbon nanotube biomass carbon composite（CNTs/CPs）microspheres were prepared by spray drying,and MnO₂nano sheets were grown on the microspheres by hydrothermal method CNTs@MnO₂、CPs@MnO₂、CNTs/CPs@MnO₂and CNTs@CNTs/CPs@MnO₂Composites,final discovery CNTs@CNTs/CPs@MnO₂It has the best electrochemical performance.At the current density of 1 A/g,the capacity reaches 251 F/g,and it can still show 78%capacitance retention after 10000 cycles.Then,CNTs@CNTs/CPs@MnO₂and different anode materials were used to form asymmetric supercapacitors,and the electrochemical performance was compared.When the anode material is CNTs/CPs,at a current density of 0.5 A/g,the capacity reaches 61.6 F/g,which can still show relatively excellent electrochemical performance.