| Summary: | 碩士 === 國立臺灣科技大學 === 化學工程系 === 87 === The material properties LiNiVO4 cathode materials prepared by a sol-gel method and PEO polymer electrolytes were investigated by XAS, XRD, AC impedance and Raman spectroscopy in this study. The relation between the material properties and the charging-discharging performance of the cells was expected to be established. It was found that Ni-O radius of the LiNiVO4 powder prepared at pH 1 is the longest among the prepared LiNiVO4 powders from the XAS results. The resistance of Li ion intercalation is the lowest and the performance of the cell obtained from the LiNiVO4 powder prepared at pH 1 is the best. On the contrary, the coordination numbers of the Ni-Ni shell is the largest among the prepared LiNiVO4 powders from the XAS results. From AC impedance analysis, it indicated PEO becomes saturated with Li salt when the [EO]/[Li] ratio is less than 10 which is larger than the value of 4~5 reported in the literature. It implies that there are some crystalline phases produced in the PEO polymer electrolytes. From Enhanced Raman spectroscopy study, the peaks of LiClO4 at 935.6 cm-1and 2930 cm-1 and the peaks of PEO at 1474.5 cm-1 and 1487.5 cm-1 shift with changing the [EO]/[Li] ratio. Meanwhile, a new peak was found at 1420.8 cm-1. It means that there are some interactions between Li ions and PEO polymers. From the XAS study, the contributions of Cl and O atoms were observed in the surrounding of Cu in the CuCl2+PEO electrolytes. However, it is difficult to distinguish the contributions of different O atoms in the surrounding of Cu in the CuSO4 + PEO and Cu(ClO4)2 + PEO electrolytes.
|
|---|
