Applied Research Of Composites Of Graphene And Polypyrrole In Aqueous Supercapacitor

Graphene, as a kind of carbon material with large specific surface area and good conductivity, is widely applied in supercapacitor. Graphene supercapacitor is based on the effect of electrical double layer and has good cyclic stability. There is another kind of supercapacitor called faradic pseudocapacitor, like polypyrrole supercapacitor, which is based on pseudo-faradic reactions. Compared to polypyrrole supercapacitor, graphene supercapacitor has lower specific capacitance. However, polypyrrole supercapacitor has a fatal flaw for its poor cyclic stability, which has severely limited its application. Based on the above, to prepare composites of graphene and polypyrrole is becoming a potential solution to make up for the lack of both sides. Therefore, this thesis has mainly done the following research:1. A modified Hummers method had been used to prepare graphene oxide that had been analyzed with SEM, TEM, XRD, FTIR and AFM.2. To reduce graphene oxide, three different methods, including heating reduction, hydrothermal-method reduction and hydroiodic-acid reduction had been used to get three different kinds of reduced graphenes that had been analyzed with SEM, TEM, XRD, FTIR and BET.3. The electrochemical performance of heat-treated graphene using KOH,Na2SO4, KCl and NaN03solution as electrolyte respectively had been analyzed by cyclic voltammetry, galvanostatic charge-discharge test and cyclic life test. A comprehensive comparison had been made among each other.4. The electrochemical performance of graphene reduced by hydrothermal method and heating method had also been studied, both of which had used NaN03solution as electrolyte, the result of which had been made a comprehensive comparison with the electrochemical performance of graphene reduced by heating.5. The electrochemical performance of polypyrrole using KOH,Na2SO4, KCl and NaN03solution as electrolyte respectively had been tested by cyclic voltammetry, and galvanostatic charge-discharge test, the result of which illustrated that the specific capacitance of polypyrrole in KOH and NaNO3electrolyte were larger than the others. In order to further compare their electrochemical performance, both of them were analyzed by cyclic life test..6. Three different kinds of composites of graphene and polypyrrole had been preparedby physical mixing method, in-situ polymerization method and hydroiodic-acid-reduction method. The electrochemical performance of the three kinds of composites using NaNO3as electrolyte had been studied, the result of which had been compared to the electrochemical performance of pure polypyrrole in NaNO3electrolyte comprehensively.