Perparation Of Carbon Nanomaterials Macroscopic Body And Their Applications In Energy Storage

Electrochemical super capacitor (ESC), a new energy storage device between the battery and traditional electrostatic capacitor, has received widespread attentions for its high specific capacitance, high power density, long cycle life and environmentally friendly. As far as the ESC, the most important component is the electrode material. As a main part of electrode material, carbon materials have experienced several kinds as porous carbon, activated carbon, carbon aerogel, carbon nanotube (CNT) and the recent research hotspot-graphene. Since CNT was first discovered in1991by Iijima, it have received worldwide attention due to its unique structure, superior mechanical properties, high length-diameter ratio, high chemical and thermal stability, super conductivity and its hydrogen storage capacity. However, the obtained CNT by traditional methods (such as graphite arc discharge, chemical vapor deposition and laser evaporation) are usually powder, which can easily result in uneven distribution and agglomeration because of the inert surface and size effect of the CNT powder. To avoid the problems mentioned above, an effective way is to make CNT powder into the macro body, such as CNT felt, CNT film, and so on. Carbon fiber (CF) is a typical electrode material of ESC for its rich pore structure and high specific surface area. Because of its high specific surface area and superior conductivity, graphene is also considered as an outstanding electrode material. Since the influence of the specific surface area and pore size structure of single carbon material, the performance of the ESC will somehow be limited. So we use the carbon composite to improve the electrode materials specific surface area and the electrical performance at the same time, so that the electrochemical properties are improved.This paper mainly studied the preparation and performances of the carbon nanotube network and ternary-carbon network composite. The morphology and structure of the obtained material were characterized by scanning electron microscope and Nitrogen adsorption isotherms. And the electrochemical performances of the obtained materials were tested by the cyclic voltammograms, galvanostatic charging-discharging, cycle life testing and electrochemical impedance spectroscopy. The specific studies are shown as follows:1. The gel method was applied to prepare the gel-carbon nanotube network precursor (g-CNTNp) and gel-carbon nanotube network (g-CNTN) by carbon nanotube powder (CNT powder). The electrochemical performances testing results show that the g-CNTN has better electrochemical performances and the specific capacitance can reach158.1F·g-1(in organic electrolyte).2. The CNT network precursor (i-CNTNp) was prepared by an interfacial standing method. After a series of subsequent treatment, the CNT network (i-CNTN) was obtained. The results show that i-CNTN not only has better electrical conductivity and mechanical property, but has better electrochemical property, and the specific electrochemical capacitance is about104.0F·g-1in organic electrolyte.3. The in situ catalyst chemical vapor deposition was applied to prepare the binary-carbon network composite (purified carbon fiber/carbon nanotube, pCF/CNT) with CNT grown uniformly on pCF. After a serise of subsequent treatments, the ternary-carbon network composite (purified carbon fiber/carbon nanotube/graphene reducting by high temperature, pCF/CNT/HRG) was obtained. The results show that the pCF/CNT/HRG has better electrical conductivity and electrochemical property, and its specific electrochemical capacitance in organic electrolyte is about220.3F·g-1.