Lu Shuhan, Wang Bingqian, Zhang Panyu, Jiang Xiaoli, Zhao Xinxin, Wang Lili, Yin Zhixiang, Wu Jianbao
School of Mathematics, Physics and Statistics, Shanghai University of Engineering Science, 333 Longteng Road, Shanghai 201620, China.
Molecules. 2022 Oct 17;27(20):6949. doi: 10.3390/molecules27206949.
Because of the abundance and low cost of sodium, sodium-ion batteries (SIBs) are next-generation energy storage mediums. Furthermore, SIBs have become an alternative option for large-scale energy storage systems. Because the electrolyte is a critical component of SIBs, fluorination is performed to improve the cycling performance of electrolytes. Based on the first-principles study, we investigated the effects of the type, quantity, and relative position relationships of three fluorinated units, namely -CF, -CF, and -CF, on the cyclic ester molecule ethylene carbonate (EC) and the linear ether molecule 1,2-dimethoxylethane (DME). The optimal fluorination was proposed for EC and DME by studying the bond length, highest occupied molecular orbital, lowest unoccupied lowest orbital, and other relevant parameters. The results revealed that for EC, the optimal fluorination is 4 F fluorination based on four -CF units; for DME, CFCFCF-, CFCFCF-, CFCFCFCF, and CFCFCFCF, four combinations of three -CF, -CF, and -CF units are optimal. The designed fluorinated EC and DME exhibited a wide electrochemical stability window and high ionic solvation ability, which overcomes the drawback of conventional solvents and can improve SIB cycling performance.
由于钠资源丰富且成本低廉，钠离子电池（SIBs）成为下一代储能介质。此外，钠离子电池已成为大规模储能系统的替代选择。由于电解质是钠离子电池的关键组成部分，因此进行氟化处理以改善电解质的循环性能。基于第一性原理研究，我们研究了三种氟化单元-CF、-CF和-CF的类型、数量及相对位置关系对环状酯分子碳酸亚乙酯（EC）和线性醚分子1,2-二甲氧基乙烷（DME）的影响。通过研究键长、最高占据分子轨道、最低未占据分子轨道及其他相关参数，提出了EC和DME的最佳氟化方案。结果表明，对于EC，基于四个-CF单元的4F氟化是最佳的；对于DME，-CF、-CF和-CF三个单元的四种组合CFCFCF-、CFCFCF-、CFCFCFCF和CFCFCFCF是最佳的。所设计的氟化EC和DME表现出宽的电化学稳定窗口和高的离子溶剂化能力，克服了传统溶剂的缺点，可改善钠离子电池的循环性能。
