Electrochemical Preparation Of Hith Capacitance Composite Polymer Electrode

The rapid development of new energy prompted the research into new electrochemical capacitors for energy storage device. The need of convenient and effective use of new energy spurred the development of electrode with high specific volume, which is one of the important factors influence the performance of electrochemical capacitors. In this paper, PEDOT and MnO2 thin film electrodes were prepared by electrochemical method. The effect of prepare conditions on the electrode performance were investigated. The infrared spectrum analysis, morphology characterization were conducted. Additionally, the electrode performance of two composite films consisted of PEDOT/MnO2 and MnO2/PEDOT were probed. The main research include:1. The PEDOT thin film electrode was prepared in LiClO4 aqueous solution, the results of morphology characterization and electrochemical test show that the PEDOT film is relatively flat, the film is formed by accumulation of nanoparticles, the grains are closely connected. The polymerization potential of EDOT unit, in LiClO4 aqueous solution, is 0.9V. The condition for preparing PEDOT thin film by constant potential method, with better performance is: polymerization potential is within 1.1-1.2V; use LiClO4 with 0.2mol/L as electrolyte concentration; the concentration of the EDOT monomer in the electrolyte is 0.01mol/L. Based on cyclic voltammetry method, PEDOT thin film electrode were prepared in different conditions, the results showed that the specific capacitance is biggest, up to 80.6F/g, when the potential of the electrochemical window is 0-1.2V at the scanning rate of 100mV/s.2. The MnO2 thin film electrode was prepared in MnSO4 aqueous solution, the results of morphology characterization and electrochemical performance test show that the MnO2 film formed continuous MnO2 layers, which is interweaved by irregular nano pieces, many pores existing. The MnO2 deposited on the working electrode when the potential is 0.8V. The deposition rate increase linearly from 1V to 1.5V, the response current reaches the extreme value when the potential is close to 1.7V. The influence of deposition rate and electrochemical aggregation window on capacitance performance of MnO2 thin film electrode were researched by cyclic voltammetry, in the range of 50mV/s-200mV/s, the specific volume of deposited MnO2 film increases with the decrease of deposition rate. The specific capacitance is biggest, up to 125.7F/g, when the potential of the electrochemical window is 0-1.5 V.3. Composite film electrodes of PEDOT/MnO2 and MnO2/PEDOT were prepared on the ITO electrode with cyclic voltammetry. The results of electrochemical test show that: both the two composite film electrodes store energy by Pseudo capacitance; the electrodes have good charge and discharge reversibility, the PEDOT/MnO2 electrode is suitable for charge and discharge of small currents, the highest specific capacitance of single electrode can reach 163.2F/g; the MnO2/PEDOT electrodes have good cycle stability, the specific capacitance of single electrode is 192.2F/g; the electrode resistance is about 25Ω,with good conductivity. Compared with the pure PEDOT electrode and MnO2 electrode, the comprehensive properties of MnO2/PEDOT composite film electrode has been greatly improved, has high specific capacity, good conductivity and good reversibility.