磷酸亞鐵鋰具有低成本、低汙染、良好熱穩定性與長循環壽命等優點，因此成為近年來熱門研究的鋰離子電池陰極材料。然而，其也有電子導電度低、離子擴散速率低與量產不易等缺點，使其電池性能受到限制。為了克服以上的缺點，許多學者提出各種方法，諸如掺雜金屬、表面塗佈與控制粒徑等，這些方法雖能有效地解決磷酸亞鐵鋰的缺點，卻使生產成本提高，降低其商業價值。為了降低成本，本論文以簡易的碳熱還原法配合工業級碳源合成磷酸亞鐵鋰，起始物全面改用工業級原料，鐵源更使用便宜之氧化鐵。 從實驗結果得知，球磨液添加量有最小限制量，本製程以煆燒溫度973 K，煆燒時間8小時所合成出的LiFePO4具有優良的導電度 (4.42×10-4 S cm-1)，對於磷酸亞鐵鋰/C複合材料，吾人亦利用XRD、SEM、TEM、EDS、DSC、CV與拉曼光譜等鑑定，以進一步了解吾人所製備材料的特性。電池性能方面，吾人所製備的材料於0.2 C充放電率，4.0 V/2.8 V 充放電電壓條件下，初始電容量為150 mAh g-1，經過50次充放電循環後，電池放電電容量幾乎沒有衰退。 Olivine-structured lithium iron phosphates (LiFePO4) become a promising cathode material because of its low cost, low toxicity, remarkable thermal stability and long operation life. However, it was hard to scale up and reported that this cathode has very low electronic conductivity and diffusion-controlled kinetics. To overcome the problems, various methods have been widely used such as lattice metal doping, surface carbon coating and optimizing the particle size. In order to cut down the synthesis cost, simplify the synthesis technology and enhance the specific capacity of the material, we introduced a carbothermal reduction (CTR) method based on the presence of PEG to synthesize well-carbon-network LiFePO4 by using industrial raw materials and chose ferric oxide as staring material. From our results, a required amount of acetone was added to the starting materials for the ball milling process and the precursor was sintered at 700 ℃ for 8 h to form crystalline phase LiFePO4 with greater electronic conductivity (4.42×10-4 S cm-1). The structure and morphology of the carbon coated LiFePO4 samples have been characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDS), and differential scanning calorimetry (DSC), cyclic voltammetry (CV), and raman spectroscopy, and so on.. Electrochemical measurements show that the LiFePO4/C composite cathode delivered an initial discharge of 150 mAh g-1 at a 0.2 C-rate between 4.0-2.8 V, and almost no capacity loss was observed up to 50 cycles
