Synthesis Of Graphene And Nickel Hydroxide Composites And Their Supercapacitor Properties

Supercapacitor is a new type of energy storage device which has the advantages of high charge-discharge efficiency, long life cycle, a wide working range, pollution-free, thus it has broad prospects for development. Supercapacitors can be divided into two types, i.e. the electric double layer capacitors and the Faraday pseudocapacitors according to storage mechanism. The electrode materials used for these supercapacitors usually are carbon materials, metals and their oxides, conductive polymers, and the respective composite materials. Graphene is a two-dimensional carbon material having various excellent performance and shows the performance of the electric double layer capacitor in supercapacitors; nickel and its oxide as a widely used cathode material of the alkaline battery are also used in supercapacitors and manifested as the Faraday pseudocapacitive performance. The composites are able to combine their respective advantages to achieve superior electrochemical performance.In this thesis, a good degree of oxidation of graphite oxide was prepared by Hummers method using expanded graphite as precursor. The graphite can be dispersed to monolithic layer with a large number of oxygen-containing functional groups under ultra-sonic oscillation. The graphene was obtained by chemical reduction with hydrazine hydrate. Graphene remained thin layer structure and a variety of analytical testing methods were used to characterize the materials.aNi(OH)2/graphene composites were successfully prepared with graphene as raw material in a simple chemical precipitation method, and we investigated the effect of different proportions of graphene in the composites to the structure and performance of the composites, and the formation mechanism was also discussed. The electrochemical tests showed that aNi(OH)2/graphene with a weight ratio of1:10showed the best property with1392F/g specific capacity and excellent cycle performance. Finally, Ni(OH)2/graphene composites were also exploratory studied with graphite oxide as raw materials.