二甲亚砜辅助液相法制备纳米级磷酸铁锂

发布时间：2018-08-04 10:13

【摘要】：随着电动自行车和新能源汽车产业发展步伐的不断加快,储能科技迅速受到越来越多人的关注,绿色能源产业对锂离子电池的要求和关注度已达到了历史最高点。锂离子电池已成为目前最被看好的动力电源。其中,正极材料对锂离子电池的性能起到了关键的作用。橄榄石结构的磷酸铁锂因其价格低廉,无毒,较高的理论比容量,优异的热稳定性和平稳的放点平台等优点,成为极具潜力的锂离子电池正极材料,成为近年来开发研究的热点。本论文首先综述了锂离子电池的一些基本特点和工作原理等,通过分析目前磷酸铁锂的合成过程中存在的一些问题,提出了一种在常压和低温的液相环境下直接快速合成粒径小而均匀的并具有橄榄石结构的磷酸铁锂的新方法。以二甲亚砜/水溶液作为反应介质,在常压和较低温度的条件下,经过很短的反应时间即可直接制得粒径小且分布均匀的单一相橄榄石结构的磷酸铁锂。将液相直接的得到的磷酸铁锂混合少量的葡萄糖在高温下短时间烧结,可以得到电化学性能优异的LiFePO_4/C。本文利用扫描电镜(SEM)、X射线衍射(XRD)、透射电镜(TEM)、红外光谱(IR)、电性能测试等对样品的表观形貌、粒径大小和晶体结构、电化学性能等进行了表征,通过对不同反应物浓度,反应时间,溶剂二甲基亚砜与水的比值,烧结时间,烧结温度条件下合成出的样品进行对比,得出了制备LiFePO_4/C材料的最优化条件。并将液相法直接制得的LiFePO_4和最优化条件下制得的LiFePO_4/C进行对比和分析,说明一定量的碳包覆和短时间的热处理对于磷酸铁锂电化学性能的提高是非常重要的。
[Abstract]:With the rapid development of electric bicycle and new energy automobile industry, more and more people pay attention to energy storage technology. The demand and attention of green energy industry for lithium ion battery has reached the highest point in history. Lithium ion battery has become the most promising power supply. Among them, cathode material plays a key role in the performance of lithium ion battery. Olivine structure lithium iron phosphate has become a potential cathode material for lithium-ion batteries because of its low price, non-toxic, high theoretical specific capacity, excellent thermal stability and stable placement platform. It has become a hot spot in recent years. In this paper, some basic characteristics and working principles of lithium ion battery are reviewed, and some problems existing in the synthesis of lithium iron phosphate are analyzed. A new method for the direct and rapid synthesis of lithium ferric phosphate with small and uniform particle size and olivine structure in liquid environment at atmospheric pressure and low temperature was proposed. Using dimethyl sulfoxide / aqueous solution as the reaction medium, lithium ferric phosphate with small particle size and uniform distribution of olivine structure can be prepared directly through a very short reaction time under the condition of atmospheric pressure and low temperature. LiFePO _ 4 / C _ (4) / C with excellent electrochemical performance can be obtained by sintering a small amount of glucose at high temperature by mixing lithium ferric phosphate directly with liquid phase. The apparent morphology, particle size, crystal structure and electrochemical properties of the samples were characterized by scanning electron microscope (SEM), X-ray diffraction (SEM), (XRD), transmission electron microscopy (XRD), (TEM), infrared spectroscopy (IR), and electrochemical properties. The ratio of solvent dimethyl sulfoxide to water, sintering time and sintering temperature were compared, and the optimum conditions for the preparation of LiFePO_4/C materials were obtained. The comparison and analysis between the LiFePO_4 prepared by liquid phase method and the LiFePO_4/C prepared under optimum conditions show that a certain amount of carbon coating and short time heat treatment are very important for improving the electrochemical performance of lithium iron phosphate.
【学位授予单位】：河南师范大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TM912

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