| This dissertation consists of two parts, the first part (from chapter to four) is about studies of electrochemical capacitor, and the other is about cathodes LiMn2O4 for Lithium ion batteries.An Electrochemical capacitor is new storing energy system between batteries and conventional capacitors. It is intensively used as memory back-up sources for computers and power sources in many fields of electronic and communication equipment because of its high specific power and good cycle life. Moreover, it can be developed for hydrid systems with regular batteries such as lead/acid batteries in electronic vehicles.Electrochemical capacitor is composed of electric double-layer capacitor (EDLC) and faradaic pseudocapacitor. Electrode materials have effects on properties of electrochemical capacitor, many carbonaceous materials such as active carbon, pyrolytic carbon, active carbon fiber and carbon nanotube were mainly used in electric double-layer capacitor. Because of synthetic conditions and cost, we studied their electrochemical properties of electronic double-layer capacitor that pyrolytic carbon was used as their electrode materials.1.capacity and discharge efficiency of polyacene capacitors were systematically studies and electrolyte is aqueous and aqueous solution a series of pristine sample were prepared by pyrolysis of phenol formaldehyde resin moulded with ZnC, this inorganic salt used together with the resin served not only as the pore-forming agent to form open pores, which grow into a three-dimensional network structure in the cured material, but also as the microstructure-controlling agent to form a loose structure dopable with bulky dopants such as BF4 and so on.2. Aqueous solution electrolyte such sulphuric acid starts to decompose about IV or so, but nonaqueous solution such as 1 mol/1 EUNBF4/PC can't decompose below 2-5V. at the same current, the capacity of capacitors with monaqueous electrglyte is higher than that of aqueous electrolytes, but the former have high internal resistance, the latter has low resistance but it erodes the systems.3.when table sugar was used as starting materials, it was used and pyrolyzed directly or was first mined with sulphuric acid after surface area of those materials is not larger than that of PAS capacity is small in their electric double-layer capacitor, specific surface area has great effect on capacity, the larger specific surface area is, the higher capacity is,.but bulk density will decrease with increase of specific surface area. So electrode materials for EDLC have both large specific area and bulk density.4. Micropores have great effects on electrode especially, micropores between 2 to 5nm can increase capacity of EDLC. Table sugar must be activated for electrolde material as EDLC some functional groups contain in material can increase capacity of EDLC.5. Amorphous RuOs xt^O was intensively used as electrode materials for pseudo capacitors. It is difficult to be used commercially because of its expensive cost. In the dissertation cheap metal oxide NiO was prepared from new method and its electrochemical properties was discussed in brief.6. The second part in the dissertation is about studies of Lithium ion battery. It was intensively used in the field of portable computer and communications, if one doubles the specific capacity of the positive electrode, e.g., by using an oxide that could reversibly intercalate ILi instead of 0.5 Li per 3d-metal, one could increase the specific capacity of the cell by 68%. In contrast, if one doubles the specific capacity of the negative electrode (LiQ-LiCe), one increases the overall specific capacity of the cell by only 12%. Thus, to improve the specific of Lithium Ion batteries, main effort should be directed toward the synthesis of newpositive electrode materials, i.e. various Lithiated oxides that could reversibly intercalate one Li atom per 3d-metal atom at about 4V versus Li. LiMn2O4 is promising candidate for cathode because of high voltage, low coat and nontoxity for environment. LiMn2O4...
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