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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/43342


    Title: 芳香族化合物碳源對磷酸亞鐵鋰電池性能之影響;Effects of Various Aromatic Compounds on the Performance of LiFePO4/C Composite Cathode by a Solid State Method
    Authors: 王冠文;Guan-wen Wang
    Contributors: 化學工程與材料工程研究所
    Keywords: 聯苯;磷酸亞鐵鋰;LiFePO4;Acenaphthene
    Date: 2010-06-22
    Issue Date: 2010-12-08 13:35:05 (UTC+8)
    Publisher: 國立中央大學
    Abstract: 磷酸亞鐵鋰 (LiFePO4)的電子導電度只有10-9 至10-10 S cm-1,導致初始電容量較低及承受大電流能耐較差。為了提升磷酸亞鐵鋰的電池性能,藉由高溫固態法,並添加不同苯環數目芳香族化合物,製備磷酸亞鐵鋰/碳複合材料,其中以15 wt.%聯苯(Acenaphthene, C12H10)改質,於0.2 C及1 C 下,分別獲得初始放電電容量157 mAh g-1 及125 mAh g-1。另外,它展示極佳的循環穩定度,於0.2 C 下,經過100 次循環數測試後,放電電容量仍有152 mAh g-1 (初始放電電容量的95.6 %),每個循環數的衰退放電電容量比率為0.044 %。 經 HR-TEM 觀測, 2 個苯環數目的碳源聯苯所合成材料,碳層均勻包覆在LiFePO4 顆粒表面,且碳層厚度為 5~10 nm;當添加具有3 個苯環數的芳香族化合物碳源蔥時,碳層並未均勻包覆於LiFePO4 材料表面,且碳層厚度為20nm,顯示聯苯所合成LiFePO4/C 材料,碳層可均勻包覆在LiFePO4 顆粒表面,且碳層厚度較薄。 聯苯所合成材料,於充放電截止電壓4.6/2.0 V 測試,經充放電速率0.2 C及5 C 的循環測試,可回復原始電容量,顯示材料結構穩定,並在10 C 之充放電速率測試下,仍有 30 mAh g-1 的放電電容量。 吾人以 XANES 及XPS 觀測,以聯苯為碳源,於不同煆燒溫度773 K、873 K 及973 K 所合成的三個樣品,XANES 與XPS 光譜圖中顯示鐵原子皆為 Fe2+成分,無Fe3+存在。 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.
    Appears in Collections:[化學工程與材料工程研究所] 博碩士論文

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