Preparation And Electrochemical Performance Of Composite Materials Based On MnO₂ And Titanium Carbon MXene

Supercapacitor is a kind of energy storage device with large capacity.Because of its high power density,long cycle life,environmental protection,fast charge and discharge speed and other advantages,it has become the new darling of energy storage devices in recent years.Although electrostatic capacitors have fast charge and discharge and high power density,their energy density is low and the stored energy is small.Batteries has the advantages of high energy density and large stored energy,but it faces the shortcomings of low power density and long charging time.As a combination of the above two advantages,supercapacitors have the advantages of large specific capacity,high power density,fast charging and discharging speed,long service life,and environmental protection.They do not require frequent maintenance and are suitable for use as high-power energy storage equipment,and has broad application value market prospects.The performance of supercapacitors largely depends on the electrode material.Currently,the most researched electrode materials on the market include:carbon-based materials,transition metal oxides and conductive polymers.The above three have their own advantages,but there have many defects,so people use the composite of two or more materials to maximize their strengths and avoid weaknesses,and composite materials have naturally become the first choice for electrode materials with excellent electrochemical properties.This thesis mainly discusses the preparation of composite electrode materials,as well as the corresponding characterization methods and electrochemical performance testing.The research content of the thesis includes the following three aspects:(1)Using Ti₂AlC as the precursor,using HF prepared from a mixed solution of HCl and LiF to etch it to obtain Ti₂C,and further using hydrothermal method to prepare?-MnO₂/Ti₂CT_x.Applying it to the electrochemical performance test,the experimental results show that at a current density of 1 A/g,the specific capacitance of the material is as high as 268.6 F/g.In the combined two-electrode system,its retention rate is still as high as 98%after 10,000 cycles,when its power density is1650 W/Kg,the energy density is 27.3Wh/Kg.(2)Using Ti₂C as the carrier,make ZIF-67 grow on its surface under oxygen-free conditions,and then prepare electrode material CoPNCS/Ti₂C under oxygen-free high temperature conditions,and test its electrochemical performance through electrochemical testing methods.The results show that at a current density of 1 A/g,the specific capacitance reaches 241 F/g,and after 500 cycles,the specific capacitance efficiency remains at 97%.(3)Co-Co PBA is used as a substrate,potassium permanganate is added to it,and Co-Co PBA@?-MnO₂ is prepared by constant temperature stirring at 150?.The electrochemical performance test is carried out.The experimental results show that the material is at a current density of 1 A/g,the specific capacitance reaches 241.8 F/g.After 5000 cycles of it,the specific capacitance efficiency remains at 99%.