Effects of Various Aromatic Compounds on the Performance of LiFePO4/C Composite Cathode by a Solid State Method

• Main Authors: Guan-wen Wang, 王冠文
• Other Authors: George Ting-Kuo Fey
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/20803845364045392763

碩士 === 國立中央大學 === 化學工程與材料工程研究所 === 98 === Electronic conductivity of pristine LiFePO4 is only 10-9-10-10 S cm-1, which leads to initial capacity loss and poor rate capability. To improve the electrochemical properties of LiFePO4 powders, LiFePO4/C composite powders were prepared with various aromatic compounds by a high temperature solid-state method. LiFePO4 powders coated with 15 wt.% Acenaphthene (C12H10) exhibited initial discharge capacities of 157 mAh g-1 and 125 mAh g-1, at 0.2 and 1 C-rates, respectively. In addition, it showed excellent cycle stability. Even after 100 cycles at 0.2 C, a discharge capacity of 152 mAh g-1 was obtained (95.6 % of its initial value) with lower capacity fading of only 0.044 % per cycle. A series of residual carbons on the surface of prepared LiFePO4 materials originating from the pyrolysis of different aromatic compounds were characterized by field-emission scanning electron microscopy, high resolution transmission electron microscopy, energy dispersive spectrometry, and total organic carbon analysis. Their electrochemical properties were investigated by cyclic voltammetry, four-point probe conductivity measurements, and galvanostatic charge and discharge tests.