| Electrochemical supercapacitor is a new energy storage equipment and component between batteries and electrostatic capacitors, which has higher energy density than that of electrostatic capacitor, higher power density than that of batteries, long-cycle life and wide-temperature range. It can be applied into many fields such as hybrid electric vehicle, mobile telephone and microcomputer. According to the principle of energy-storage there are two types of capacitors: electric double-layer capacitor and faradaic pseudocapacitor. Generally, the electrode materials of the supercapacitor mainly include carbon materials, metal oxides and conductive polymers. It is considered that the electrode-materials are the important part of the electrochemical supercapacitor.In this thesis, we have reviewed the newest development in research of electrode materials of electrochemical capacitor devices, and prepared composite electrode materials. The structures and morphologies of these materials were characterized by XRD, SEM, TEM, et al. Their electrochemical performances have been evaluated by galvanostatic charge-discharge, cyclic voltammetry (CV) and electrochemical impedance spectra. The charge-storage capability of the electrodes materials has also been measured. This thesis consists of five parts.The first chapter summarizes the fundamental principles, characterizations and applications of supercapacitors, especially the recent progress of researches on supercapacitors using carbon materials, metal oxides and conductive polymers as electrode materials.The second chapter describes simply the conception, principium and the data analysis of cyclic voltammetry (CV), galvanostatic charge-discharge, and electrochemical impedance spectroscopy (EIS), which are referred in this research.The third chapter shows a strategy to synthesize two molecule sieve-based metal hydroxides (Co(OH)2/13X and Ni(OH)2/13X) by a liquid-precipitated method, which used the 13X molecule sieve as the substrate. The structures and morphologies of these materials were characterized by XRD, SEM. The results display that the metal hydroxides grow on the surface of 13X molecule sieve and the crystals of them areβ-Co(OH)2 andα-Ni(OH)2 respectively. The tests of cyclic voltammetry indicate that the curve of CV is similar to parallelogram, the electrode-reaction is nearly reversible and the redox peaks are obvious, implying that they are favorably used as electrode materials in the electrochemical supercapacitor. The results of galvanostatic charge-discharge gives that the special capacitance of Co(OH)2/13X and Ni(OH)2/13X can be up to 176 F/g and 134.2 F/g in potassium hydroxide resolution(1 mol/L), respectively.The fourth chapter shows a novel strategy to synthesize two composite electrode materials (Co(OH)2/CISC and Ni(OH)2/CISC) using grafted-carboxyl starch. The morphology, thermal stability and chemical component of the Ni(OH)2/CISC were characterized by SEM, XRD, and FTIR. The electrochemical performances of composite electrode were examined by cyclic voltammetry (CV), galvanostatic charge-discharge, and electrochemical impedance spectroscopy (EIS) techniques . The results of cyclic voltammetry show that they are favorable for preparing the electrode materials of the electrochemical supercapacitor because of their good reversibility for electrode-reaction. The results of galvanostatic charge-discharge show that the special capacitance of Co(OH)2/13X and Ni(OH)2/13X can be reached to 147 F/g and 115 F/g in potassium hydroxide resolution(1 mol/L), respectively.The fifth chapter shows that CeO2 nanoparticles with uniform size were synthesized by homogeneous precipitation method, and then CeO2/PANI nanocomposites were obtained by coating it with PANI. The structural components, crystalline phase, shape and size distuibution and thermal stability of the samples were characterized by TG/DTA , XRD, TEM and FTIR. The results indicate that the resultants exhibited high thermal stability because of core-shell structure.
|
PDF Full Text Request