锂离子电池新型电解液的制备和电化学性能的研究

发布时间：2018-03-06 00:29

  本文选题：锂离子电池　切入点：草酸二氟硼酸锂　出处：《兰州理工大学》2014年硕士论文　论文类型：学位论文

【摘要】：目前,锂离子电池的电解液体系主要是由LiPF6电解质锂盐和碳酸酯类有机溶剂构成。但LiPF6易分解及潮解,因此研发新型电解质锂盐是电池领域的一个研究热点。 本文利用一种新方法实现了草酸二氟硼酸锂(LiODFB)和LiBF4两种电解质锂盐的联产,相比于以前的制备方法更加经济、简单,且产率更高。基于LiODFB的新型电解液体系0.9mol L1LiODFB-SL(环丁砜)/DMS(亚硫酸二甲酯)的氧化分解电势高于5.5V,有望成为一种新型的5V高电压锂离子电池的电解液体系。当应用于MCMB(中间相炭微球)/Li.LiFeP04/Li电池时,0.9mol L-1LiODFB-SL/DMS电解液体系在电极材料表面形成了稳定、有效的界面膜,提高了电池的循环性能、倍率性能等。 作为上述研究结果的延伸,实验中进一步将LiODFB中的草酸根基团用含硫基团所替代,首次制备出了硫酸二氟硼酸锂(LiBF3SO4),并对其基本物理性质进行了研究。进一步的，，以LiPF。基电解液体系作为参照物,系统研究了LiBF2SO4基电解液的电化学性能。研究表明,得益于LiBF2SO4对电极/电解液界面膜的改善作用,1.0mol L-1LiBF2SO4-EC(碳酸乙烯酯)/DMC(碳酸二甲酯)(1：1,体积比)电解液体系组装的实验电池具有良好的电化学稳定性,稳定的循环性能和优异的倍率性能。特别是在80℃时,LiBF2SO4-EC/DMC电解液体系仍表现出了良好的热稳定性,稳定的循环性能以及良好的倍率性能。 这些工作,既建立起了具有实际应用前景的新型电解液体系,又为新型锂盐的设计、研发提供了指导。
[Abstract]:At present, the electrolyte system of lithium-ion battery is mainly composed of lithium salt of LiPF6 electrolyte and organic solvent of carbonate, but LiPF6 is easy to be decomposed and deliquescent, so the research and development of new electrolyte lithium salt is a research hotspot in battery field. In this paper, a new method is used to realize the co-production of LiODFB (LiODFB) and LiBF4 electrolyte lithium salts, which is more economical and simpler than the previous preparation method. The new electrolyte system based on LiODFB (0.9mol / L 1LiODFB-SLS) is expected to be a new electrolyte system of 5V high voltage lithium ion battery. When it is applied to MCMB, the oxidation decomposition potential of DMSs (dimethyl sulfite) is higher than 5.5V, which is expected to be a new type of electrolyte system for 5V high voltage lithium ion battery. In the mesophase carbon microsphere / Li 路LiFeP04 / Li battery, the electrolyte system of 0.9mol L-1 LiODFB-SL-DMS formed stable on the surface of the electrode material. The effective interface film can improve the cycle performance and rate performance of the battery. As an extension of the above results, the oxalic acid radical group in LiODFB was further replaced by sulfur-containing groups in the experiment. LiBF3SO4H _ 2SO _ 4 was prepared for the first time and its basic physical properties were studied. The electrochemical properties of LiBF2SO4 based electrolytes were systematically studied by using LiPF.base electrolyte system as reference material. Due to the effect of LiBF2SO4 on the electrode / electrolyte interfacial membrane, the experimental cells assembled with 1.0 mol L -1 LiBF2SO4-EC (dimethyl carbonate / 1: 1, volume ratio) electrolyte system have good electrochemical stability. Especially at 80 鈩

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