本文選題：濕法磷酸 + 磷酸鐵��； 參考：《武漢工程大學》2014年碩士論文

【摘要】：隨著社會的發(fā)展，，能源問題的日益突出，人們對資源利用率的提高越來越重視。鋰離子電池由于工作電壓高、循環(huán)壽命長、能量密度大、對環(huán)境友好等優(yōu)點而受到廣泛的關注。因此,大力發(fā)展價格低廉、能量密度高的可充式鋰離子電池,具有積極重要的科學意義，而且具有可觀的潛在商業(yè)價值。其中含鐵系列正極材料以其價格低廉、原料豐富易得、綠色環(huán)保等優(yōu)點,受到電池行業(yè)的廣泛關注,特別是磷酸鐵鋰正極材料。 磷酸鐵鋰正極材料具有放電比容量高、循環(huán)性能優(yōu)良、較好的熱穩(wěn)定性等諸多優(yōu)點，而致國內外爭相研究。而磷酸鐵作為合成磷酸鐵鋰的重要原料也越來越受到關注。 本文以濕法磷酸和硫酸亞鐵分別為磷源和鐵源，通過合成、沉淀過程制備磷酸鐵，研究了摩爾投料比、反應pH、氨水滴加速度、表面活性劑PEG（10000）添加量和煅燒溫度等對合成磷酸鐵的影響，并以制備的磷酸鐵為磷源和鐵源通過溶膠-凝膠法制備了磷酸鐵鋰材料。采用了粒度分布、振實密度、比表面積、紅外光譜（IR）、X射線衍射(XRD)和掃描電子顯微鏡(SEM)等手段對合成的磷酸鐵及磷酸鐵鋰材料的結構和微觀形貌進行表征，同時通過電池測試系統(tǒng)及電化學工作站對磷酸鐵鋰材料的電化學性能進行檢測。 結果表明：制備磷酸鐵的最佳工藝條件為：磷鐵摩爾投料比為1.0:1，PEG用量為原料硫酸亞鐵質量的3.0%，氨水滴加速率為35.62ml/h，反應的pH控制在2.5。在此工藝條件下制備得到的磷酸鐵為無定型二水磷酸鐵粉體，經450℃煅燒后為斜方晶系的納米片磷酸鐵粉體，磷酸鐵微粒厚度約為70-100nm，平均粒徑1000nm，分散性好，粒度分布均勻。該工藝具有原料廉價，操作簡單，合成時間短和能耗小等優(yōu)點，是一種節(jié)能且經濟的新方法。 通過優(yōu)化條件下制備的磷酸鐵為原料通過溶膠-凝膠法制得的產物為磷酸鐵鋰/碳的復合材料，通過表征可得磷酸鐵鋰正極材料結晶度良好，晶形完整，為橄欖石晶體，粒度分布均勻，團聚現象少，磷酸鐵鋰表面疏松多孔，比表面積可達13.61m2/g，D50=3.6μm，粒度分布窄，振實密度為1.24g/cm3。磷酸鐵鋰/碳復合材料通過電化學性能檢測具有較好的首次放電比容量和穩(wěn)定的循環(huán)性能。在0.1C倍率下首次放電最高能到達到145.5mAh/g，40次充放電循環(huán)后保持在143.1mAh/g，衰減率為1.61%；樣品分別在0.2C，0.5C，1.0C三種倍率下的首次放電比容量分別為138.7mAh/g、129.1mAh/g和119.2mAh/g，通過40次循環(huán)后比容量分別下降至128.9mAh/g、115.8mAh/g和101.5mAh/g，衰減率分別為7.1%、10.3%和17.5%。電荷轉移阻抗小，該工藝制作的材料可逆性好，極化較小，電化學性能較穩(wěn)定。
[Abstract]:With the development of society and the increasingly prominent energy problem, people pay more and more attention to the improvement of resource utilization ratio. Lithium-ion batteries have attracted wide attention due to their high operating voltage, long cycle life, high energy density and environmental friendliness. Therefore, the development of rechargeable lithium ion batteries with low price and high energy density has positive and important scientific significance and has considerable potential commercial value. Due to its low price, abundant raw materials and green environmental protection, iron containing series cathode materials have attracted wide attention in battery industry, especially lithium iron phosphate cathode materials. Lithium iron phosphate cathode material has many advantages, such as high discharge capacity, good cycling performance, good thermal stability and so on. Iron phosphate as an important raw material for the synthesis of lithium iron phosphate has attracted more and more attention. In this paper, wet-process phosphoric acid and ferrous sulfate were used as phosphorous source and Tie Yuan, respectively, to prepare ferric phosphate through synthesis and precipitation process. The molar ratio of feed, pH of reaction, acceleration of ammonia droplet were studied. The effect of the amount of surfactant PEG 10000) and calcination temperature on the synthesis of iron phosphate was studied. The lithium iron phosphate material was prepared by sol-gel method using the prepared iron phosphate as the phosphorus source and Tie Yuan as the source. Particle size distribution, vibrational density, specific surface area, IR spectra, X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the structure and microstructure of the synthesized iron phosphate and lithium iron phosphate materials. At the same time, the electrochemical performance of lithium iron phosphate was tested by battery test system and electrochemical workstation. The results showed that the optimum technological conditions for the preparation of iron phosphate were as follows: the molar ratio of phosphorus to iron was 1.0: 1g as the mass fraction of ferrous sulfate, the dropping rate of ammonia water was 35.62 ml / h, and the pH of the reaction was 2.5. The ferric phosphate powder prepared under this condition is amorphous iron dihydrate powder. After calcined at 450 鈩

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