Perparation Of Graphene And Its Composites With Their Applications In Energy Storage

Electrochemical Supercapacitor (ESC) is a new kind of energy storage device with many outstanding properties, such as high specific capacity, good reversibility, long cycle life, good environmental stability and wide application perspectives. Supercapacitors are increasingly gaining attention because they fill a gap between batteries and ordinary capacitors. The choosing of the electrode material is the critical factor to the preparation of electrochemical capacitor. Graphene has been the most promising candidate of electrode materials since its discovery.owing to the many advantages graphene has like large specific surface area, great electrical conductivity and so on. However, supercapacitors, which are consisted of pure graphene, do not demonstrate desired capacitance as expected. Polyaniline (PANI) is a common conducting polymer, which has been considered as an important electrode material due to its cost efficiency, operation simplicity, high chemical and environmental stability. Unfor tunately, supercapacitors comprising electrodes which are made up of pure PANI, do not fulfill people’s need of high capacitance, long cycle life. Active carbon fiber (ACF) has long been used as electrode material and other field with high significance because of its good conductivity, high strength and large specific surface area. Whereas pure ACF need to be futher modified forhigh apparent density, good acid resistance and so forth. In order to improve the electrochemical performance of the supercapacitors, graphene are employed to modify the PANI and ACF.In this paper, we primarily studied the preparation and their electrochemical properties of graphene and its composites, and comparing the properties of graphene and CNTs in their composites. Morphology and structure of the obtained materials were characterized by transmission electron microscope (TEM), field effect scanning electron microscopy (FE-SEM). X-Ray Diffraction was also adopted to analyze the component of the obtained material. In addition, the electrochemical performances of the obtained materials were characterized by cyclic voltammograms (CV), galvanostatic charging/discharging. The detailed information is listed as follows:1-Graphene oxide was prepared by Hummers method. And then the obtained graphene oxide was reduced by chemical method and high temperature hydrogen reduction process respectively. Comparing the two reduction methods mentioned above, graphene obtained by chemical method has better electrochemical performance withthe specific capacitance of104.4F/g(organic electrolyte).2. The CGR/PANI and CNTs/PANI composites were papered by in-situ polymeri-zation. In contrast to CNTs/PANI composites, CGR/PANI composites have better electrochemical performance and the specific capacitance of148.4F/g (organic electrolyte).3. By first immersing ACF into GO water solution, followed by hydrogen reduction at high temperature, the GR/ACF composites was achieved. While CNTs/ACF were prepared by chemical vapor deposition (CVD). The results showed that the graphene/ACF composites have higher specific capacity and cycling stability compared to CNTs/ACFand ACF.