Preparation Of Graphene/Poly (3,4-ethylenedioxythiophene) Composites And Their Properties

Electrochemical capacitor is one type of environmentally friendly energy storage devices, which exhibits high energy density and long cycle life. The electrode material is the most important factor to decide the energy storage performance of electrochemical capacitor. Graphene has a very large surface area and excellent conductivity. Its open surface and the regularity of its lamellar structure is conductive to speed up the rate of ion desorption. These unique properties have made it into the most promising electrode materials. Poly(3,4-ethylenedioxythiophene(PEDOT) shows large pseudo-capacitance, high conductivity, good thermal stability and other excellent features. Here, the target of the thesis is to develop composite electrode materials with high-performance. Several GE/PEDOT composites have been fabricated, and the relationship between their structure and performance has been investigated systematically. The electrochemical properties are studied also. The main contents are as follows.(1) Graphene oxide/PEDOT (GEO/PEDOT) was prepared by in situ polymerization in acetonitrile, then was reduced to GE/PEDOT composite. The as-prepared products were characterized by means of various instruments. The result indicated that the product obtained after the reaction time of 12h showed the well-dispersed morphology and the best electrochemical performance. PEDOT nano spheres were deposited uniformly on the sheets of GE. The specific capacitance of GE/PEDOT was 652F/g in base electrolyte, which was much higher than that of individual component.(2) GE/PEDOT was synthesized directly in acetonitrile by in situ polymerization, with needle-like PEDOT coating on the GE sheets. The morphology and property of the as-prepared composite were compared with those of GE/PEDOT obtained indirectly. The results showed that the electrochemical performance of the GE/PEDOT obtained by direct method was better, with the specific capacitance of 795F/g, lower inner resistance, and energy density of 49Whkg-1.(3) The GE/PEDOT composites with nanofiber PEDOT on the surface of GE were also obtained in aqueous media by indirect method of in situ polymerization--reduction. The influences of the dopant of polystyrene sulfonic acid (PSS) on the morphology and properties were investigated. The capacitance of GE/PEDOT composite was 300F/g in 6M KOH, when the scanning rate is 5mV/s. The electrode material also showed good cycle stability.