Studies On Preparation And Application Of Multi-walled Carbon Nanotubes/Polyaniline Composites For Supercapacitor Electrode

In recent years, supercapacitors as the electrical energy storage systems have attracted growing attention due to the higher specific power and higher specific energy. As the electrode material of supercapacitors, conducting polymer has many advantages, such as, quick and efficient discharge, withouting charge/discharge control circuit, long cycle life, temperature relief, and environmental amicability. It also possesses characteristics of semiconductor or conductor after effectively doped. Polyaniline (PANI) is one of the most interesting conducting polymers due to its environmental stability, ease in preparation, exciting electrochemical, optical and electrical properties.Carbon nanotubes has unique mechanical, electricity, magnetism performance because of its' light size and big relative surface. In this dissertation, first, the multi-walled carbon nanotubes (MWCNT) were dissolved well into aniline, and we synthesized MWCNT/PANI composites electrode materials by chemical oxidative polymerization and electrochemical polymerization, respectively, and study its electrochemical capacitive performance for supercapacitors. The main studies are as follows:1. The MWCNT were dissolved well into aniline via reflex process in the dark and then the dark-red MWCNT- aniline solution was obtained.2. The MWCNT/PANI composites were prepared via simple chemical oxidative polymerization, and the microstructure, the thermal stability, the supercapcitive behaviors of these composite films were investigated with SEM, TGA, FTIR, cyclic voltammetry, charge-discharge, and impedance spectroscopy. The results show that the effect of MWCNT on composites is a framework, PANI can coat-growed around the MWCNT-framework. Comparing with the pure PANI, the MWCNT/PANI composites have more active sites for faradic reaction and larger specific capacitance.3. The MWCNT/PANI composite films were prepared by electrochemical polymerization, the microstructure and supercapcitive behaviors of these composite films were investigated through SEM, XPS, cyclic voltammetry, charge-discharge, and impedance spectroscopy. The results show that the MWCNT/PANI composite films have porosity structure owing to the presence of MWCNT, this can improve the utilization of PANI greatly. The MWCNT/PANI composite films were provided with higher doping degree, lower defect density and larger specific capacitance than the pure PANI film. The specific capacitance of the MWCNT/PANI composite films are 434,481,500 F/g with 0.2,0.4, 0.8 wt% MWCNT, which is much higer than 356F/g of pure PANI film.