Study On Synthesis,Characterization And Properties Of Manganese Oxide/carbon Supercapacitor Electrode Materials

Supercapacitor is a new type of energy storage devices different from conventional capacitors and batteries.It has great application potentials in information,electronics,hybrid electric vehicles,portable consumer electronic devices and other fields,due to its fast charge-discharge rate,high power density and long cycle life.The electrode material is considered to be the key part of a supercapacitor and directly affects the performance of supercapacitor.Manganese oxide has been considered as the most promising electrode material in terms of its high theoretical capacitance,abundant resources,low-cost virtues and environmentally friendliness.This thesis is aimed at the preparation of manganese oxide-based electrode materials,and the examination and discussion of their electrochemical mechanism.The main works and conclusions of this thesis are as following.(1)Manganese oxide electrode materials with different morphology were synthesized using three different preparation process.Both their crystal and morphological structures and their electrochemical performances are discussed.The results show that the electrochemical performances of the electrode materials are different due to their various microstructures and morphology.The larger porosities are beneficial to improve the specific capacitance of manganese oxide electrode materials.(2)The MnO2/C nanocomposite electrode materials with various morphological structures were synthesized via a facile water bath method,with KMnO4as oxidant and carbon black(C)as reductant.Experimental results indicate that the reaction time,reaction temperature and the reactant mass ratio have great effects on the microstructure and morphology of the manganese oxide nanocomposites,and thus affect their electrochemical performances.When the reaction temperature is 80 ?,and the reaction time is 12 h,the MnO2/C nanocomposites have the highest specific capacitance values,which is 184 F/g with a current density of 0.2 A/g.(3)Nanosheets Mn0O2 CFP(Carbon fiber paper,CFP)composite electrodes were synthesized via a simple in situ redox reaction between potassium permanganate(KMnO4)and CFP without any other binder.The MnO2/CFP nanocomposite electrode with a reaction time of 12 h displays a superior electrochemical performance with a specific capacitance of 537.5 F/g at 0.5 A/g.With the prolonging of reaction time,the loading of MnO2 increases,which hinders the diffusion of ions in the electrolyte solution and increases its diffusion path,resulting in the reduction of the electrochemical properties.The experimental process and theory researches in this thesis can provide certain experimental references and theoretical directions for the design and preparation of other electrode materials and related mechanism research.