Preparation And Electrochemical Properties Of Manganese Oxide, Conducting Polymer And Graphene

Supercapacitor is a new device of accumulated energy, which is the higher watt densityand energy density than storage battery and is superior to conventional capacitor incapacitance value. Due to the advantage of high energy density, high watt density, high life ofcycle-use, economical and environmental-friendly, high speed of charge and discharge, widerange of work temperature and high coefficient of securing, Supercapacitor hascomprehensive application in the correspondence, electronics, electric automobile, aviationand space industry, defense technology and so on. Metal oxide, conducting polymer, porouscarbon materials are used as main materials in electrode of supercapacitor. The articleinvestigated three electrode materials in supercapacitor, and they were characterized by highresolution scanning electron microscopy(SEM), X-ray powder diffraction(XRD), Ramanspectrum(Raman) and ultraviolet-visible spectrum(UV-vis). The differences of theirdeterioration of capacitor were revealed by Cyclic voltammetry(CV), Electrochemical impedancespectroscopy(EIS) and Galvanostatic charge/discharge (GCD). The thesis has several maincontents:1、Manganese dioxide electrode materials were prepared by hydrothermal method, inwhich KMnO4used as precursor. Three different morphology of α-, β-, δ-is readily obtainedby adjusting the experimental parameters such as hydrothermal temperature, reaction time andthe initial concentration of the reactants. Their electrochemical performances wereinvestigated, revealing optimalizing crystalline shape and morphology as electrode materialsin supercapacitor and conditions made them.2、Polyaniline and polypyrrole nanoparticles were synthesized using aniline and pyrroleas precursor, ammonium persulfate as oxidant by chemical oxidation under low temperature. The products were used to serve as electrode materials to assemble electrochemical capacitor.By comparing electrochemical performance of the prepared materials, it is found thatpolyaniline is superior to polypyrrole as electrode material in supercapacitor.3、Using flaky graphite as precursor, graphite oxide is obtained by advanced Hummersmethod. The prepared product is transformed into graphite oxide under ultrasonic condition.The graphene was synthesized via chemical reduction method, which has apparent distinctionof performance with one in thermal expansion and reduction process under vacuum condition.