Research On The Capacitance Performance Of Polyaniline And Its Composite Materials

With higher energy density than that of electrostatic capacitor and higher power density than that of batteries, electrochemical super-capacitor is considered as a new energy storage eqiupment. It can be used in many fields such as transportation, aviation and aerospace, communication, microcomputer etc. Supercapacitor can be classified to three kinds according to the principle of energy-storage: electric double-layer capacitor, faradaic pseudocapacitor and hybrid capacitor. Carbon material, metal oxide and conducting polymer are the electrode materials researched most extensive nowadays.In this dissertation, polyaniline(PANI) and polyaniline/activated carbon composite material(PANI/C) were synthesized in chemical oxidation method. The materials were characterized using scanning electron microscopy and infrared spectrum. Single electrodes and hybrid capacitors of both materials were prepared, with l.Omol/L H2SO4 aqueous solution and 1.0mol/L LiPF₆/EC+DMC organic solution as electrolyte respectively, which were investigated with the aids of the measurements such as impedance spectrum, cyclic voltammetric(CV), galvanostatic charge/discharge, and so on. The results show that, both PANI and PANI/C performance well in 1.0mol/L H₂SO₄ aqueous solution. The Specifc capacitance of PANI/C single electrode reach to 448.7F/g, much higher than that of pure activated carbon(AC). The hybrid capacitor using PANI/C cathode and AC anode has the life of more than 1000 cycles, and specific capacitance amounts to 83.1F/g. The capacitance behavior of PANI in organic electrolyte was also well. The specific capacitance of hybrid capacitor with PANI cathode is 36.0F/g, discharging from 1.5V to 0V. The leakage current of the capacitor was rather small, and the cycle life is excellent. Polyaniline/MnO2 composite material(PANI/MnO₂) was also prepared and its electrochemical behavior was investigated. Aparently, polyaniline and its composite materials are promising electrode materials applied in electrochemical supercapacitor.