Preparation Of Carbon Nanotube Sponges And Their Nanocomposites For Application In Supercapacitors

Rely on large specific capacitance, supercapacitors can store much more charge, coupled with its high power density, long cycling life and other disadvantages, so it has a wide range of application in electricity, electronics, aerospace and other fields. As one of the key factors affecting the performance of supercapacitor, the materials is particulary important. So it is necessary to increase the electrode material(particulary new materials) the development and utilization. In this paper, carbon nanotube sponges have been handled by a series of processing. After that, it can be directly used as electrodes for supercapacitors with a three-dimensional network structure. Furthermore, some craftworks, such as coating, can be ellipsis. Thus, it has important implications for future application.Main research works for carbon nanotube sponges include: Use a certain proportion of mixed acid to treated so as to introduce a number of functional groups(including-OH,-COOH, and so on). This can improve their hydrophilic, and the carbon nanotube sponges and aqueous electrolyte will be sufficiently infiltrates. The study found mixed acid-treated carbon nanotube sponges are preferably immersed in an aqueous electrolyte. And the electrochemical tests showed that, the carbon nanotube sponges have a best electrochemical behavior after they had been treated for 6 hours in the mixed acid. At a scan rate of 1m V/s, the materials have a specific capacitance of 67F/g.On this basis, the composite materials of carbon nanotube sponges-polyaniline(PANI) had been prepared with electrochemical deposition, and we used FT-IR, XRD, SEM, TEM and other methods to characterize their structures. At the same time, electrochemical techniques(CV, constant current charge and discharge, EIS and so on) had been used to test the electrochemical behavior of the composite materials with different polyaniline content. The results show that, into a two-electrode system, when the percentage of polyaniline is about 63%, the composite materials have the best properties. The capacitance of the electrode is 200F/g at a 0.5A/g current density, and it can retain 180F/g at 5A/g. After 10000 cycles with a speed of 100 m V/s, it can retain 75.2% of the initial capacitance. When assembly asymmetric capacitor with the materials, the energy density can reach to 15.1Wh/Kg, power density is 1598W/Kg. After 3000 cycles with 2A/g, the capacity retention ratio is 94.3%.It is also prepared carbon nanotube sponges-nickel hydroxide(Ni(OH)2) composite materials and analyzes its structure and electrochemical behavior. The data indicated that the composite materials have the best properties with the mass percentage content of Ni(OH)2 at about 53%. At 0.5A/g, the electrode has a capacity of 588.4F/g, as well as retention 400F/g at 5A/g. After 10000 cycles with the rate at 50 m V/s, the capacity retention ratio is 94%.