| Summary: | 碩士 === 明志科技大學 === 化學工程研究所 === 99 === The work reports the preparation of the high performance LiFePO4/C cathode material by a hydrothermal and post-thermal process. The characteristic properties of LiFePO4/C materials were examined by thermal gravimetric analysis (TGA), X-ray diffraction (XRD), micro-Raman spectroscopy, scanning electron microscopy (SEM/EDX), and elemental analysis (EA), and AC impedance method. Electrochemical impedance spectroscopy (EIS) and Micro-Raman spectroscopy were used to examine the characteristic properties of LiFePO4/C materials. The electrochemical properties of CR2032 coin cell was tested at 0.1C~7C. The polystyrene (PS) polymer was used as a carbon source. The content of PS polymer was varied at a range of 0~5wt.%. The temperature of post-thermal treatment was used in the range of 750~850oC. The synthesis environments have two types：oil bath and oven bath. It was found that the highest specific discharge capacity of LiFePO4/C materials at 0.1C is 167 mAh g-1 and a coulumb efficiency was 97~98%. However, the LiFePO4/C materials by oil bath environment, the specific discharge capacity and the coulomb efficiency at 1C is 135 mAh g-1 and current efficiency of 90%. In addition, it was revealed that the highest specific discharge capacity of LiFePO4/C materials by oven bath at 7C was 90 mAh g-1. The above results indicated that the as-prepared LiFePO4/C materials by a hydrothermal and post-thermal treatment process show excellent electrochemical performance. Those LiFePO4/C materials show a good potential candidate for Li-ion battery applications.
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