【作者】 张莉莉；

【导师】 汝坤林； 金成昌；

【作者基本信息】 江南大学 ， 分析化学， 2008， 硕士

【摘要】 随着能源与环境问题的日益突出以及现代科技的高速发展,人们对电池的性能提出了更高的要求。锂离子电池以其工作电压高、循环寿命长、能量密度高、无环境污染、无记忆效应等优势而成为人们的首选。正极材料的质量对锂离子电池的性能影响很大,所以发展高能锂离子电池的关键技术之一是正极材料的开发。目前商品化的锂离子电池正极材料有LiCoO₂、LiNiO₂、LiFePO4、LiMn₂O₄等。纵观正极材料市场,各种材料都有各自的优点和缺点,锰系正极材料（主要为尖晶石型LiMn₂O₄）价格低廉,易于制备,且锰的资源丰富,对环境无污染,即使LiMn₂O₄的循环性较差、高温下容量易衰减,但综合比较LiMn₂O₄具有较高的性价比,被公认为是21世纪最有竞争力的锂离子电池正极材料。论文首先综述了国内外锂离子电池正极材料尖晶石型LiMn₂O₄的研究进展,研究主要集中在合成制备和掺杂改性方面,又简单介绍了化学分析法中主要的分析法—原子吸收光谱法。论文的研究重点分为两个部分:一、锂离子电池正极材料LiMn₂O₄的物理性能分析;二、锂离子电池正极材料LiMn₂O₄的化学成分分析。在物理性能分析中主要研究了测定LiMn₂O₄材料的pH值、粒度分布、比表面积、振实密度、晶体结构、水含量的方法,测定值与其产品出厂规定值相一致。在LiMn₂O₄的化学成分分析中研究了测定主成分Mn含量、杂质成分Fe、Na、Ca、Mg、Pb、Cd的方法。测定材料中的Mn采用络合滴定法,关键是准确标定滴定用EDTA标准溶液的浓度,并且指示剂能够明显指示滴定终点,此方法准确度高,最终Mn含量53.78%,与对比的仪器测定值54.9%在允许的测定误差之内,RSD=2.04%,精密度好。测定材料中的Fe、Na、Ca、Mg采用火焰原子吸收光谱法,此种方法中主要考虑的问题是:（1）测定Fe、Na、Ca、Mg时标准工作溶液和待测液中的盐酸浓度,要从灵敏度和保护仪器两个方面来综合选择;（2）基体Mn和Li是否对测定Fe、Na、Ca、Mg产生影响,如果影响显著则要在标准工作溶液中加入相当于待测液中同量的Mn和Li;（3）测Na时需要加入消电离剂CsCl,消电离剂可以抑制Na在原子化时电离的损失,增大测Na的灵敏度和准确度,也是测Na必不可少的;（4）测Ca、Mg时需要加入释放剂LaCl3,释放剂可以基本消除基体和其他杂质元素的干扰,使检测有更高的准确度。测定材料中的Pb、Cd采用石墨炉原子吸收光谱法,此种方法中主要考虑的问题是硝酸浓度、Pb和Cd的灰化温度和原子化温度、基体改进剂对测定产生的影响。根据LiMn₂O₄材料中各元素含量分析的结果可知,本论文所建立的化学成分分析方法准确度高,精密度好,满足此种材料的分析要求。更多还原

【Abstract】 With energy and environmental issues have become increasingly prominent, as well as the rapid development of modern technology, people request a higher demand on the performance of batteries. Lithium-ion batteries become the first choice for its high-voltage, long cycle life, high energy density, no pollution, no memory effect, and other advantages. the quality of Cathode material play a great impact on the performance of lithium-ion battery, the development of cathode materials is one of the key technologies of the development of high-energy lithium-ion batteries.The current commercialization of lithium-ion battery cathode materials have LiCoO₂, LiNiO₂, LiFePO4, LiMn₂O₄, considering cathode materials in the market, various materials have their own strengths and weaknesses.Manganese lithiumn oxides（mainly for the spinel LiMn₂O₄） have the following benefits:low price, easy preparation, and manganese is rich in resources, the environment pollution-free, even if LiMn₂O₄ has a poor cycle , high temperature capacity easily decay, but a more comprehensive comparison LiMn₂O₄ high cost-effective, is recognized as the most competitive of the lithium-ion battery cathode materials in the 21st century.This paper first reviewed research progress of lithium-ion battery cathode materials spinel LiMn₂O₄ at home and abroad, mainly concentrating in the study of synthesis and doping modified,and then briefly introduced the main analysis method - atomic absorption spectrometry . This paper focused on two parts: First, the physical performance analysis of lithium-ion battery cathode materials LiMn₂O₄; Second, the chemical composition analysis of lithium-ion battery cathode materials LiMn₂O₄. Analysis of the physical properties of LiMn₂O₄ concluded pH, particle size distribution, surface area, tap density, crystal structure, water content ,the Analysis values of LiMn₂O₄ were in line with pre-specified values. the chemical composition analysis of LiMn₂O₄ major for the determination of contents of Mn,Fe,Na,Ca,Mg,Pb,Cd. The method of determination of Mn is complex titration, the key is accurate preparation for the concentration of EDTA standard solution ,as well as the indicator can clearly instruct titration end, the method is accurate, content of Mn is 53.78 percent , compared with the 54.9 percent of the value of equipment determination that allowed in the Measurement error, a high precision with RSD = 2.04%. Determination of Fe, Na, Ca, Mg by FAAS, the main issues to be considered were: （1）Selecting the concentration of hydrochloric acid in the standard solutions and sample solutions of Fe, Na, Ca, Mg was from two aspects of sensitivity and equipment protection. （2）Whether the matrix Mn and Li have an impact on the determination of Fe, Na, Ca, Mg, it would have to add equivalent amount of Mn and Li of sample solutions in the standard solutions. （3）It was necessary to add ionization buffer CsCl in Na measurment, ionization buffer could reduce the loss of ionization of Na ,it also increased measurement sensitivity and accuracy. （4）It need to add releasing agent LaCl3 in Ca, Mg measurment,the releasing agent could basically eliminate interferences of impurities and other elements and enable the examination to have a higher accuracy. Determination of Pb, Cd used graphite furnace atomic absorption spectrometry, the main issues to be considered were nitrate concentrations, Pb and Cd ashing and atomization temperatures, the impacts of matrix modifiers on the determination of Pb and Cd. In accordance with analysis results of LiMn2O4 materials, The analysis methods of LiMn2O4 chemical composition established in this paper were accurate and precise, meeting the requirements of such material.更多还原