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摘要分别以碳酸锰、铁粉、氢氧化锂、磷酸和蔗糖为锰源、铁源、锂源、磷源和碳源，先通过球磨与喷雾干燥获得前躯体，再采用高温固相法制备了锂离子电池碳包覆磷酸锰铁锂正极材料。先通过X射线衍射对样品的结构进行表征，再通过电化学测试研究了材料的电化学性能。结果表明：通过对LiMnPO4/C材料铁掺杂后得到的LiMn1-xFexPO4/C 材料，其电化学性能显著增强。当x=0.5时，LiMn0.5Fe0.5PO4/C正极材料具有最佳的电化学性能，在0.1C倍率下其首次充放电比容量为162.0mAh/g，首次充放电效率为90.0%，材料经过16次循环后充放电比容量为154.6mAh/g，比容量保有率为95.4%。同时，进一步讨论了铁的掺杂量对材料电化学性能的影响。研究发现，在一定程度上增加铁的掺杂量会提高材料的电化学性能。31049
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毕业论文关键词： 磷酸锰铁锂；锂离子电池；铁掺杂；电化学性能
Abstract
To synthesize a series of LiMn1-xFexPO4/C as cathode material for lithium ion batteries, the precursor was prepared by ball-milling and spray-drying manganese source manganese carbonate, iron source iron powder, lithium source lithium hydroxide, phosphorus source phosphoric acid and carbon source sucrose, then the precursor was subjected to high temperature solid-state reaction. The structure of the sample was characterized by X ray diffraction, and the electrochemical properties of the materials were studied by electrochemical tests. The results showed that: the electrochemical properties of LiMn1-xFexPO4/C materials are significantly enhanced by the iron-doping of LiMnPO4/C. When x = 0.5, LiMn0.5Fe0.5PO4/C cathode materials exhibits the best electrochemical property. Its charge and discharge specific capacity is 162.0mAh/g and the charge discharge efficiency is 90.0% in the first cycle at 0.1C. Its charge and discharge specific capacity remained 154.6mAh/g and specific capacity retain rate is 95.4% after 16 cycles. At the same time, the effect of the doping amount of iron on the electrochemical properties of the materials is discussed. It is found that the electrochemical properties of the materials can be increased by increasing the doping amount of iron in a certain extent.
KeyWords： LiMn0.5Fe0.5PO4;lithium ion batteries;iron-doping;electrochemical properties
目 录
1 文献综述 1
1.1 引言 1
1.2 锂离子电池概述 1
1.2.1 锂离子电池的诞生及发展过程 1
1.2.2 锂离子电池结构及工作原理 1
1.3 锂离子电池正极材料研究现状 2
1.3.1 层状结构的材料 3
1.3.2 尖晶石结构材料 3
1.3.3 橄榄石结构材料 4
1.4 磷酸锰锂研究综述 4
1.4.1 磷酸锰锂正极材料的特点 4
1.4.2 铁掺杂磷酸锰锂的合成方法 5
1.4.3 磷酸锰锂的改性研究 6
2 样品制备与实验方法 7
2.1 实验药品与仪器 7
2.1.1 实验药品 7
2.1.2 实验仪器 8
2.2 高温固相法合成LiMn1-xFexPO4 9
2.3 电极的制备及实验电池的组装 9
2.3.1 电极片的制备 9
2.3.2 电池的组装 10
2.4 材料的表征 10
2.4.1 粒度测定 10
2.4.2 物相分析(XRD) 10
2.4.3 电导率的测定 10
2.5 电化学性能测试 11
2.5.1 充放电循环性能测试 11
2.5.2 循环伏安测试(CV) 11
2.5.3 交流阻抗测试(EIS) 11
3 结果与讨论 11