Three Dimensional Graphene And Polyaniline Nanocomposites For High Performance Supercapacitors

Supercapacitors, known as an intermediate energy storage devices between dielectric capacitors and batteries, have attracted a great deal of interest for its high power density, fast rates charge-discharge, reliable cycling life and safe operation.The main electrode materials studied for the supercapacitors are carbons, metal oxides, and conducting polymers which focused on improving electrochemical performance. Graphene based electric double layer capacitors materials with a wide range of potential applications, shows many outstanding advantages such as high specific surface area, excellent conductivity, low production cost and mass production. Among pseudocapacitors materials, conducting polyaniline has been.extensive studied due to its low cost compared to noble metal oxides and supernal pseudocapacitance with high doping-dedoping rate during charge-discharge process.In this paper,three dimensional graphene(3D graphene) and polyaniline(PANI)as supercapacitors electrode materials were studied. To improve the electrochemical performances of the devices, 3D graphene/PANI hybrid electrode materials were synthesized and the preparation technology has been extensively researched. Their properties with three-dimensional network structure can be enhanced arising from the high specific surface area and excellent mechanical strength and conductivity of graphene, combined with large pseudocapacitance of polyanilne.Firstly, 3D graphene with high specific capacitance were respectively prepared by there methods: self-propagating high temperature synthesis(SHS),named as 3D-G;sulfuric acid sucrose carbonization method, named as 3D-GSZ; and the high temperature tube furnace sucrose carbonation method, named as 3D-GHZ. In the preparation, carbon source and reactant concentration parameters were researched.Then, the preparation of high specific capacitance polyaniline by the chemical oxidative polymerization was researched from several process parameters such as polymerization time, drying method, heat treatment, sulfuric acid concentration.Finally, 3D graphene/PANI hybrid electrode materials improved electrochemical properties were successfully synthesized just by regulating the concentration of graphene. The main results are as follows: 3D graphene with well electric double layer performance has been prepared with Ca CO3 as carbon source by SHS, sucrose and graphene quality ratio of 8 and 2 by sulfuric acid sucrose carbonization and the high temperature sucrose carbonation, respectively. The optimum process conditions of polyaniline polymerization are 0.1 M sulfuric acid concentration, 3℃ for 6 hours,vacuum drying process. The specific capacitance of polyaniline is 622.4 F/g at thecurrent density of 0.5 A/g. As for the preparation of 3D graphene/PANI composites,the optimum quality ratio of aniline and graphene is 1:8. The specific capacitance of3D-G/PANI, 3D-GHZ/PANI and 3D-GSZ/PANI composites were 587.8, 579.0 and651.4 F/g at the current density of 0.5 A/g, respectively. The 3D graphene synthesized by self-propagating high temperature synthesis and high sucrose carbonization methods added in composites can improve its rate performance and cycle stability, and 3D graphene by sulfuric acid sucrose carbonization can raise its specific capacitance performance.