高电压锂离子电池电解质溶液亚硫酸乙烯酯类双功能成膜分子的构建及性能研究

Recent research show that the performance of interface film between electrode surface and electrolyte plays an important role on the properties of high voltage lithium ion batteries. Ethylene sulphite (ES) is one kind of good anode film-forming molecule according to the fact that it has a similar structure as ethylene carbonate (EC), which is a base solvent in the traditional electrolyte. In particular, ethylene sulphite-based substances may also participate in the formation of the cathode interfacial film by introduction of electron withdrawing groups in the molecule, which is expected to realize the regulation of the cathode interfacial film at the same time. Thereinto, on the basis of the results of quantum calculations, a number of the derivatives of ethylene sulphite will be designed and synthesized. We will evaluate the effects of optimized bi-functional molecules in the electrolyte on the battery performance at high voltage. Especially, the optimized functional molecules involved in the formation process of the interface layers on the electrodes at high voltage operating, and the intrinsic relationship of the composition, structure, morphology with properties of interface films will be investigated by quantum chemical calculation method, combined with spectroscopic techniques and a various of electrochemical methods. Based on the results, we will put forward the forming conditions of the controllable two electrodes surface films.

最新研究表明，正负极界面膜对于高电压锂离子电池的性能有重要作用。亚硫酸乙烯酯（ES）与传统电解液的主体溶剂分子碳酸乙烯酯（EC）在结构上相似，是一类有良好应用前景的负极成膜功能分子添加剂。特别是，通过改变亚硫酸乙烯酯中的功能基团，引入吸电子基官能团，还可能使得其参与正极界面膜的形成，从而有望同时实现对正极界面膜性能的调控。本项目结合理论计算，设计构建并合成吸电子基官能团取代的亚硫酸乙烯酯类物质，并将其作为电解质溶液的双功能成膜分子，以此提高高工作电压锂离子电池的性能。通过理论计算结合电化学、谱学表征等方法，研究在高工作电压条件下，优选出的双功能成膜分子在正负极材料表面参与形成界面膜的过程，以及所形成的正负界面膜的组成、结构和性质，并提出性质可控的正负极界面膜的形成方法。

正负极界面膜对于高电压锂离子电池的性能有重要作用。本项目根据不同的官能基团对于锂离子电池正负极材料成膜性能的影响，通过理论计算筛选出几种可能在正负极同时成膜的含氟烷基或者含硫氧双键的功能分子,将四氟磺内酯（TFBS）、（氟烷基苯磺酰基）乙腈 （PSPAN）、2,4-丁磺内酯（HBAG）以及1-对甲基苯磺酰咪唑（PTSI）等物质首次作为电解液的功能添加剂，用于高工作电压锂离子电池，研究了其在正负极表面的成膜性能，提出其可能的成膜机理。研究结果表明，这些物质均能在正负极上形成性能优良的界面膜，是一类有良好应用前景的双功能成膜添加剂。这项工作为锂离子电池高工作电压电解液添加剂的选择提供了一个可行的思路，为高压锂离子电池容量和循环稳定性的提高提供了新的技术方法和基础研究数据。