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摘要LiFePO4工作电压相对较高，良好的热稳定性能和循环性能，对环境友好和价格低廉等优点，因此广泛受到人们的关注。在锂离子电池应用上, 此材料被认为是极具潜力的锂电池正极材料之一。但是锂离子扩散系数和电子电导率很低，改变其晶体结构、形貌和尺寸可以有效提升LiFePO4的性能，这些性质又可以由不同的合成条件和合成方法来调控。本文主要通过水热合成法配以表面活性剂聚乙二醇400（PEG400）来辅助合成LiFePO4，研究LiFePO4在水相体系下的性能，通过X射线衍射（XRD）材料表征手段和循环伏安法测试电化学性能，确定PEG400辅助合成的作用，PEG400虽不参与反应但是可以促进LiFePO4形成能产生较好电化学性质的形貌与结构。在制备过程中暂定反应物摩尔比为3:1:1，反应物摩尔浓度为0.11molL-1，PEG400与水比例1.25:1，反应时间为10h，本反应完成后进行后续碳包覆得到最优配比。41163
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毕业论文关键词：LiFePO4，聚乙二醇400，水热合成法，循环伏安法
Abstract
The LiFePO4 operating voltage is relatively high, good thermal stability and the performance of the cycle, the environment friendly and low price, etc., so widely concerned by people. In the application of Li ion battery, this material is considered to be one of the anode materials for the lithium battery. But lithium ion diffusion coefficient and electron conductivity is very low, change the crystal structure, morphology and size can effectively enhance the LiFePO4 performance, these properties can be regulated by different synthetic conditions and methods. This paper mainly by hydrothermal synthesis method with surface active agent polyethylene glycol 400 (PEG400) to assist synthesis of LiFePO4,performance of the study of LiFePO4 under water phase system，by X-ray diffraction (XRD) and cyclic voltammetry electrochemical performance test to determine the PEG400 assisted synthesis, PEG400, although did not participate in the reaction but can promote LiFePO4 formation can produce better electrochemical properties on the morphology and structure. In the process of preparing tentative reactant molar ratio of 3:1:1 and molar concentration of reactants 0.11molL-1, PEG400 and water ratio of 1.25:1, reaction time is 10h, after the completion of the reaction of follow-up of carbon coated obtain the optimal ratio.
Keywords：LiFePO4, polyethylene glycol 400, hydrothermal synthesis,cyclic voltammetry
目 录
1 绪论 1
2 锂离子电池简介 1
2.1 锂离子电池研究背景 1
2.2 锂离子电池的发展 1
2.3 锂离子电池的优点 2
2.4 锂离子电池的工作原理及结构特点 4
2.5 锂离子电池正极材料 6
2.5.1 钴酸锂正极材料 6
2.5.2 镍酸锂 6
2.5.3 锰酸锂 6
2.5.4 磷酸铁锂 6
2.6 锂离子电池的应用 7
2.7 磷酸铁锂合成方法 8
2.7.1 高温固相反应法 8
2.7.2 微波辅热法 8
2.7.3 溶胶凝胶法 9
2.7.4 喷雾热分解法 9
2.7.5 水热合成法 9
3 试验方法与仪器 9
3.1 实验原料及器材 10
3.2 材料表征 11
3.2.1 X射线衍射分析（XRD） 11
3.2.2 扫描电镜（SEM） 11
3.3 实验步骤 12
3.3.1 磷酸铁锂的制备 12
3.3.2 电极的制备 13