Preparation Of Manganese-Based Electrode Materials For Supercapacitor And Their Electrochemical Properties

Supercapacitors have the advantages of fast charge and discharge rate,high power density,safety and reliability,etc.,making them a new type of energy storage device with a good development prospect.Among the numerous pseudocapacitive materials,manganese-based oxides/sulfides have high theoretical capacity,simple preparation process,abundant resource storage and low cost,which make manganese-based oxides and sulfides become very important electrode materials for supercapacitors.However,manganese oxides with low conductivity limits the actual high capacity;manganese sulfides with poor cyclic stability impedes their application.Based on the existing problems of manganese oxides and sulfides,this paper adopts a simple electrochemical deposition method to synthesis materials of manganese oxides and sulfides,and makes a series of detailed analysis and explorations on their electrochemical properties.The detailed research content is as follow:?1?Preparation and electrochemical properties research of high performance manganese oxide electrode materials.MnO₂/CC composites with different Mn³⁺/Mn⁴⁺ratios?CC is conductive carbon cloth?were prepared by means of potentiostatic electrochemical deposition by regulating the electrochemical deposition temperature.We characterized and analyzed the structure and morphology of MnO₂/CC electrode materials by means of XPS,XRD,SEM and TEM.The results show that as the deposition temperature rose to 70°C,the ratio of Mn³⁺/Mn⁴⁺gradually increased to 0.99,when the electrodeposition temperature reached 90°C,the ratio of Mn³⁺/Mn⁴⁺decreased to 0.70.The electrochemical performance was tested and analyzed by CHI760E electrochemical workstation,and the relationship between Mn³⁺/Mn⁴⁺ratio in the electrode and electrochemical performance was discussed.The experimental results show that MnO₂-70 electrode has good electrochemical performance.In additional,the action of the double exchange interaction of Mn³⁺-O-Mn⁴⁺and oxygen vacancy are combined to explain the reason for improvement of electrochemical performance.In order to further explore the practical application of MnO₂-70 electrode,an asymmetric quasi-solid supercapacitor was assembled by combining with the cathode material FeOOH/C.This device exhibites a high energy density of 55.7 wh kg^-11 and high power density of 6870 W kg^-1,while also has good flexibility.?2?Preparation and electrochemical properties study of high performance manganese sulfide electrode materials.MnS/NF composite samples?NF is nickel foam?were prepared by means of cyclic voltammetry electrochemical deposition by regulating the number of cycles.In order to enhance the cyclic stability of the MnS/NF electrode materials,it was carbon coated to obtain MnS/C/NF composites,at a constant temperature of 25°C using dopamine hydrochloride and trimethylmethylaminomethane as carbon sources.The structure and morphology of MnS/NF and MnS/C/NF electrode materials were characterized and analyzed by Raman,XPS,SEM and TEM,and their electrochemical properties were tested and analyzed by CHI760E electrochemical workstation.The relationship between the structure and electrochemical properties of electrode materials was also discussed.The results show that the carbon coated electrode has high capacity and good cycling stability.The MnS/C/NF electrode materials has high capacity of 812 F g^-1 at the current density of 1 A g^-1 than MnS/NF(721 F g^-1).After 5000 times of continuous constant current(20 A g^-1)charge and discharge,its capacity retention rate can receive 98%.In order to further explore the practical application of MnS/C/NF,an asymmetric supercapacitor was assembled with activated carbon?AC?as the anode material,and its electrochemical performance was tested.