| Supercapacitor ( also called electrochemical supercapacitor )can be classified into two types according to the mechanism of energy storage: electrical double layer capacitor (EDLC), utilizing electrolyte charging at the electric double layer on electrode surface by Non Faradaic process, and pseudocapacitor involving fast Faradaic reactions such as intercalation, underpotential deposition or redox processes occurring at or near a solid–electrode surface at an appropriate potential. Activated carbons are the most often used EDLC electrode material because of their low cost and versatile existing forms. An e?cient charging of the electrical double layer requires materials with a high surface area and pores adapted to the size of ions, which is crucial for EDLC performance.Carbon materials such as powders, ?bers, aerogels and nanotubes are widely used for supercapacitor applications. The performance of these carbon materials have been studied thoroughly and used in industrial applications and scientific researches. However, systematic researches of other carbon materials and discoveries of unknown materials are still needed.In this dissertation, firstly, a systematic study including the carbonization parameters, the formation mechanism of pore structures, preparations of composite materials, electrochemical properties of gelatin, as a carbon precursor, was performed; secondly, the preparation process and electrochemical properties of carbon spheres produced by chemical vapor deposition were studied; finally, the preparation, the formation mechanism and electrochemical properties of carbon microcoils were investigated. The main research work in the present dissertation can be summarized as follows:a) Gelatin based carbon microspheres were produced from gelatin spheres by heat treating at 250℃and carbonization. The empty gelatin microspheres (GMs) and glutaraldehyde crosslinked gelatin microspheres (CGMs) were characterized by thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). It was found that CGMs had an equal slight weight loss more than GMs from 300℃in air and nitrogen atmosphere respectively. The melting temperature (Tm) of GMs and CGMs were both at 228℃. After being heat treated at 250℃and acid treated in sulfuric acid solution for 7 h, the GMs heat treated in air had a foam like core/solid shell structure and that heat treated in nitrogen had solid cores/shell structure, and CGMs were all solid microspheres with cracks. After carbonization, the foam like core/solid shell structure was maintained, and the properties of the as prepared carbon materials were analysed.b) Several kinds of composite spheres were produced from CaCO3 particles and gelatin. The active carbon spheres produced from the composite spheres, whitch the mass ratio of nano CaCO3 and gelatin was 2, was the most suitable material for supercapacitor compared with other gelatin based carbon spheres. The carbon fibers/carbon spheres composite material had a low specific capacitance because of large percentage of gelatin based carbon spheres and low resistance because of the carbon fibers.c) Benzene and acetylene were used in chemical vapor deposition (CVD) process to produce carbon spheres. A double furnace apparatus and a one furnace apparatus were used for the pyrolysis of precursors. The temperature of the first furnace in the double furnace apparatus had not effect on the diameter of produced carbon spheres, and the pyrolysis temperature should over 1100℃. The diameter and accretion of prepared carbon spheres decreased along the direction of gas flow and with the increasing of gas flow rate.d) The steam activated carbon sphere had a specific capacitance of 131 F/g and the value of equivalent series resistance (ESR) of the supercapacitor was 7.5 ; the KOH activated carbon sphere had a specific capacitance of 131 F/g and the value of ESR of the supercapacitor was 7.5 . Compared these two kinds of activated carbon, the one prepared from KOH activation had higher capacitance, while the steam activation was easy to operate and low cost. So the steam activation was more efficient in our lad.e) The carbon micro coils had a carbon co substrate and were vertical with the co substrate. The coil diameter decreased and length increased with the increasing of pyrolysis temperature from 710 to 750℃. The specimen obtained at 730℃had a substrate of proper thickness and thoughness, highest percentage of coils, and a BET surface area of 511 m2/g after steam activation. The porosity distribution was primarily micro pores, with some meso and micro pores. The value of specific capacitance was 56.4 F/g and the ESR value of the supercapacitor was 12.5 .f) On the back surface of co substrate of carbon micro coils, Ni particles exhibited face centered cubic (fcc) phase and hexagonal close packed (hcp) phase. Only hcp Ni was found in the vicinity of the gas inlet, and Ni monolith shaped as flat hexagonal plates. Far from the gas inlet, Ni grains aggregated into flat plates without total fusion. The evidences above indicated that the mechanism of micro diameter carbon micro coils was different from that of nano diameter carbon micro coils.
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