双氟磺酰亚胺锂合成工艺研究进展及其改进方向

Research progress and improvement direction of synthesis process of lithium bis(fluorosulfonyl)imides

摘要:

锂电池电解液通常由锂盐、溶剂、添加剂三部分构成，锂盐作为组成之一，很大程度上决定着电池的能量密度、循环性能与安全问题。目前主要的商业化锂盐六氟磷酸锂（LiPF6）存在热稳定性差、易水解等问题，限制了锂电池在极端情况尤其是宽温区的使用；而双氟磺酰亚胺锂（LiFSI）因其较好的热稳定性、电导率高、高低温性能优异有望取代LiPF6成为新一代锂盐。目前，LiFSI仍存在合成成本高以及高纯产品难以获得的问题，迫切需要对现有的工艺进行改进以及开发新的合成路线。本文对LiFSI现有的合成工艺进行了总结与归纳，细致分析了各工艺的优缺点。在这基础上,文章提出了LiFSI合成工艺中优化合成步骤顺序、研发新型硅氮烷原料、创新设计氟化剂等改进方向。这些合成工艺的改进与优化举措，将进一步促进LiFSI产业的发展及其在新能源锂电池领域中的应用。

Abstract:

The electrolyte of lithium battery is usually composed of three parts: lithium salt, solvent and additives, and lithium salt, as one of the components, largely determines the energy density, cycle performance and safety of the battery. At present, the main commercial lithium salt is lithium hexafluorophosphate (LiPF6), which has problems such as poor thermal stability and easy hydrolysis, thus limiting the use of lithium batteries in extreme situations, especially in wide temperature areas. Lithium bis(fluorosulfonyl)imide (LiFSI) is expected to replace LiPF6 as a new generation of lithium salt due to its good thermal stability, high conductivity, and excellent high and low temperature performance. At present, LiFSI still has the problems of high synthesis cost and difficult to obtain high-purity products, and there is an urgent need to improve the existing process and develop new synthesis routes. In this paper, the existing LiFSI synthesis processes are summarized, and the advantages and disadvantages of each process are analyzed in detail.On this basis, the paper puts forward the improvement direction of LiFSI synthesis process, such as optimizing the sequence of synthesis steps, developing new silazane raw materials and innovating the design of fluorinating agents. The improvement and optimization of these synthesis processes will further promote the development of the LiFSI industry and its application in the field of new energy lithium batteries.