| As new kind of energy storage devices, electrochemical capacitors have been applied in many fields because of their high energy density, high power density and long cycle-life. The electrochemical capacitor can be classified into two categories based on the mechanism of storage:one is electrical double-layer capacitor which utilizes mainly the separation of electronic and ionic charges at the interface between electrode materials and the electrolyte solution and the other is the pseudo-capacitor which is based on the Faradaic redox reactions occurring within the active materials of electrodes. Recently, a great interest has focused on the development of the electrochemical capacitor with the properties of flexibility, lightweight and environmental benign, in order to meet the various requirements of modern gadgets. So it is important to fabricate the novel conducting composites used as the electrode materials. In this thesis, polypropylene filter (PPF) is chosen as the substrate because of its relatively high surface-to-mass ratio, good mechanical property and flexibility and chemical resistance while PPy, manganese dioxide and Nickel oxide are chosen as active materials. The composites can be prepared easily by using a method of polymerization in vapor phase, and fit the characteristics of capacitor electrodes and provide inherent flexibility as well as porosity.(1) Polypyrrole (PPy)/polypropylene fibrous membrane (PPF) composite materials with different PPy contents are prepared through in situ chemical oxidation polymerization in the pyrrole atmosphere at room temperature by using the FeCl3-6H2O dissolved in methanol and acetonitrile as oxidant. The morphology of the composite is examined by scanning electron microscope (SEM), the conductivities of the composites are measured by convenient four-probe method, and the properties of the capacitor cells assembled by the obtained PPy/PPF are investigated by cyclic voltammetry (CV), galvanostatic charge/discharge and electrochemical impedance spectroscopy (EIS) measurements. The results show that the morphology, conductivity and the capacitor properties of the composite are influenced strongly by the solvent of the oxidant. The capacitor assembled by the PPy/PPF prepared by using acetonitrile as the solvent for FeCl3·6H2O can adapt for quick charge/discharge, and exhibit the highest capacitance of about 72.5 F g-1 when the PPy content is about 8.0%.(2) Composites of PPy/MnO2/PPF have been prepared through in situ chemical oxidation polymerization by using FeCl3·6H2O mixed with MnO2as oxidant in the pyrrole vapor atmosphere at room temperature. The morphology and structure of the composites are examined by SEM and XRD spectroscopy. The properties of the capacitor cells assembled by composites are evaluated by CV, galvanostatic charge/discharge and EIS methods. The results reveal that the morphologies, conductivities and the capacitor properties of the composites are influenced strongly by the content of MnO2·The capacitors assembled by PPy/MnO2/PPF exhibit the quick charge/ discharge property, and the highest capacitance of about 110 F g-1 is obtained when the PPy/MnO2 content is about 17.4%.(3) Composites of PPy/NiO/PPF have been prepared through in situ chemical oxidation polymerization by using FeCl3·6H2O mixed with NiO as oxidant in the pyrrole vapor atmosphere at room temperature. The morphology of the composite is examined by SEM, the conductivities of the composites are measured by convenient four-probe method, and the properties of the capacitor cells assembled by PPy/NiO/PPF are investigated by CV, galvanostatic charge/discharge and EIS measurements. The results show that the morphology, conductivity and the capacitor property of the composite are influenced strongly by the contents of the PPy/NiO. The capacitor assembled by the PPy/NiO/PPF can adapt for quick charge/discharge, and exhibits the highest capacitance of about 105 F g-1 when the PPy/NiO content is about 15.7%. |
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