Research On The Conducting Polymers For Electrochemical Capacitor Electrode Materials

In recent years, supercapacitors as the electrical energy storage systems have attracted growing attention due to the higher specific power than batteries and higher specific energy than conventional capacitors. Considerable efforts have been devoted to developing and improving the performance of new available electrode materials.This thesis consists of three parts. The first chapter concentrated on the survey the fundamental principles, characterizations and applications of supercapacitors, especially the recent progress of the supercapacitors using carbon, transition-metal oxide and conducting polymer as electrode materials and the hybrid supercapacitors. Based on this information I put forward my purposes to solve some existed questions.Two polyaniline derivates (polybenzidine and polydiphenylamine) and polyaniline nanofibers were studied in the second chapter. This chapter is divided into three parts.1. Polybenzidine (PBZ) was polymerized by using chemical method in organic system and with (NH4)₂S₂O₈ as oxidant, HClO4 as dopant. The electrochemical behaviors of PBZ electrode were studied by cyclic voltammetry, charge-discharge test and electrochemical impedance techniques. The specific capacitance of PBZ electrode is up to 150 F/g. After 500 cycles, the capacitance has only 16.7% loss.2. Poly(diphenylamiline) (PDPA)doped with H₃PW₁₂O₄₀ was synthesized in solid-state method. The electrochemical capacitor performances were researched with cyclic voltammetry, charge-discharge and electrochemical impedance techniques. This material has low resistance in 0.5 mol/L HCl solutions. The specific capacitance of PDPA is 80F/g in 0.5 mol/L HCl.3. PANI nanofibrils were synthesized for the first time by using chemical oxidative polymerization under hydrothermal conditions. The effects of concentration of aniline, doped acid and the reaction time on the morphology of PANI were researched. The electrochemical performance of polyaniline nanofibers and polyaniline in bulk was compared in our experment.