钴酸锂超细粉末的制备及其电化学性能表征-微电子学与固体电子学专业论文.docxVIP

II II Abstract Lithium cobalt oxide (LiCoO2) possesses high specific capacity and good cyclic stability, and is currently one of the most widely used cathode materials for Li-ion batteries. They have been conventionally synthesized by solid-state reaction at temperatures over 850 °C, resulting in relatively large particle size and difficulty in controlling stoichiometry because of high activation energy for the diffusion of reacting species in solid state and volatilization of lithium at high temperatures. The larger particle sizes not only have smaller surface areas that limit electrochemical reactivity, but also lead to slower charging and discharging rates and lower power density. To overcome these difficulties, many efforts have been devoted to developing LiCoO2 with smaller particle size, and solution based sol-gel synthesis have emerged as an attractive alternative. In such process, reacting species can be mixed thoroughly in solution, making it possible to complete the synthesis with lower temperature and shorter reaction time. In this dissertation, the LiCoO2 electrode material have been systematically investigated. Lithium cobalt oxide powders were synthesized by sol-gel process using four different organic acids as chelating agents, such as citric acid, maleic acid, propionic acid and acrylic acid, and metal acetates as the source of metal ions as well as oxidants. Effect of four different organic acids on the synthesis of LiCoO2 powders was investigated through X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. Among them, pure LiCoO2 powders could be prepared by using acrylic acid as chelating agents. Therefore, acrylic acid was chose to synthesize the lithium cobalt oxide powder by sol-gel and electrospinning, respectively. X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used to characterization the microstructure and morphology of sol-gel and electrospinning powders.