【作者】 张丽娜；

【导师】 郑洪河；

【作者基本信息】 河南师范大学 ， 物理化学， 2010， 硕士

【摘要】 锂离子电池具有能量密度大,自放电率低,对环境污染小等优良特性,目前已经应用到移动终端电子产品,混合动力电动车等产业,是近年来新能源领域的研究热点。随着科技的不断进步,对锂离子电池性能的要求也越来越高。提高能量密度,拓宽电池使用温度范围,提高电池安全性能等问题是广大锂离子电池研究者面临的严峻挑战。这些关键技术的亟待解决,使得添加剂在锂离子电池中的应用已势在必行。而添加剂的选择和优化是改善室温离子液体电解质与锂离子电池电极材料相容性,进而解决这些技术问题的重要途径。相比于有机添加剂无法消除的易燃性,铵盐等无机盐具有安全性高,价格低廉,原料易得等优点,如果以适当用量溶解于适宜的电解液体系,将有可能在基本不提高成本,不改变生产工艺的基础上有效改善电池的一些宏观性能。自1993年J.O. Besenhard[1]将N₂O作为锂离子电池无机成膜添加剂以来,这方面的研究一直很少。本文研究了天然石墨负极在添加多种铵盐,锂盐,钠盐,钾盐的传统电解液中的电化学嵌脱锂性能,通过选择和优化,筛选出能改善石墨负极性能的含添加剂的电解液体系。并进一步研究经过添加剂优化的电解液体系与正极材料的相容性。实验测试手段主要为电化学性能测试,SEM,FTIR等,实验主要内容和结论如下:（1）筛选添加剂。先后在1mol/LLiClO₄/EC+DMC（1:1 by v）和1mol/LLiPF₆/EC+EMC（1:1 by v）电解液中分别添加0.02mol/L的LiF,KF, NaF, NaCl,Na₂CO₃,Na₂SO₃,NH₄F,NH₄Cl,（NH₄）₂SO₄,CH₃COONH₄等10种无机盐,通过电化学性能测试筛选出性能相对优异的三种盐Na₂SO₃,（NH₄）₂SO₄,CH₃COONH₄。（2）优化电解液体系。在1mol/LLiPF₆/EC+EMC（1:1 by v）电解液中分别添加0.02mol/L Na₂SO₃,（NH₄）₂SO₄,CH₃COONH₄。与在1mol/LLiClO₄/EC+DMC（1:1 by v）电解液中的结果相比,在此电解液中添加的效果更好。（3）优化浓度。在1mol/LLiPF₆/EC+EMC（1:1 by v）电解液中分别添加0.01mol/L和0.04mol/L的Na₂SO₃,（NH₄）₂SO₄,CH₃COONH₄。与浓度为0.02mol/L时的结果作比较,发现浓度为0.02mol/L时的效果好于另两个浓度时的效果。（4）筛选与正极材料LiFePO₄的相容性良好的电解液体系。当以分别添加了0.02mol/LNa₂SO₃,（NH₄）₂SO₄,CH₃COONH₄的1mol/LLiPF₆/EC+EMC（1:1 by v）为电解液体系,以LiFePO₄为正极,锂片做负极时,此电解液体系显示良好的性能。就三种添加剂而言,橄榄石型LiFePO₄在含CH₃COONH₄的电解液中电化学综合性能最好,其次是（NH₄）₂SO₄,Na₂SO₃。经过一系列的工作,最终确定三种添加剂各有特点,并没有哪一种显示出绝对的优越性。不过这也给我们提供了更大的选择余地和发展空间,使得添加剂的使用更有灵活性。更多还原

【Abstract】 Li-ion batteries have the high energy density, low self-discharge rate, less pollution to environment and other excellent properties, and now have been applied to industriesthe such as mobile terminal electronics, hybrid electric vehicles; Research in the field of new energy have become hot spots in recent years. As technology advancing, demands for the performances of lithium-ion batteries have also become more and more harsh. The vast number of lithium-ion battery researchers face severe challenges such as improve energy density, broadening using temperature range, improve safety performance and so on. Call for immediate solution of these key technologies make to the application of additives for lithium-ion battery has become inescapable. And selection and optimization of additives is important way to improve compatibility of the room temperature ionic liquid electrolyte and lithium-ion battery electrode materials, then solve these technical problems.Compared with the flammability of organic additives which can not been eliminated , ammonium and other salts with a high security, low price, easy to get raw materials, etc. If dissolving appropriate amount in the appropriate system, it would be possible to improve some macroscopic performances of the battery costneutrality and not change the production process. Since 1993, JO Besenhard [1] took N₂O as a inorganic film-forming additive of lithium-ion batteries, Research in this area has been very little.In our paper, the natural graphite anode in traditional electrolytes which were added several kinds of ammonium salts, lithium salts, sodium salts, potassium salts was researched on its electrochemical lithium insertion-deinsertion properties, through the selection and optimization, filtering out the additive system improving the performance of graphite anode , and further study compatibility of optimized electrolyte additives system and cathode materials. Experimental test methods are mainly electrochemical performance testing, SEM, FTIR, etc, the main contents and conclusions of the experiments are as follows:（1） Filtering out the additive. 0.02mol / L of LiF, KF, NaF, NaCl, Na₂CO₃, Na₂SO₃, NH₄F, NH₄Cl, （NH₄）₂SO₄, CH₃COONH₄were added in 1mol/LLiClO₄/EC + DMC（1:1 by v） and 1mol/LLiPF₆/EC+EMC （1:1 by v）electrolyte, filter out the relatively superior performance of three kinds of salt, Na₂SO₃, （NH₄）₂SO₄, CH₃COONH₄ through the electrochemical performance testing.（2）Optimization of the electrolyte system. 0.02mol/LNa₂SO₃,（NH₄）₂SO₄, CH₃COONH₄ were added in 1mol/LLiPF₆/EC + EMC（1:1 by v） electrolyte. Compare with 1mol/LLiClO₄/EC + DMC（1:1 by v） electrolyte, these were better.（3）Optimization of the concentration. 0.01mol / L and 0.04mol / L of Na₂SO₃, （NH₄）₂SO₄, CH₃COONH₄ were added in 1mol/LLiPF₆/EC + EMC（1:1 by v） electrolyte. Compare the results with the concentration of 0.02mol / L, the results when the concentration 0.02mol / L were better than the others .（4） Filtering out electrolyte system having a good compatibility with LiFePO₄ cathode material. When the electrolyte system were 1mol/LLiPF₆/EC + EMC（1:1 by v） added 0.02mol / L Na₂SO₃, （NH₄）₂SO₄, CH₃COONH₄, LiFePO₄ as the cathode, lithium film as the anode, this electrolyte system shows good performance . In terms of the three additives, the performance of olivine-type LiFePO₄ in the electrolyte containing CH₃COONH₄ is the best overall , followed by （NH₄）₂SO₄, Na₂SO₃.After a series of work,one thing was made certain: the three kinds of additives have some different characteristics, there were no absolute superiority. However, this also provides us with greater choice and development space, allowing more flexibility in the use of additives.更多还原