Wang Ya-Qian, Xu Hengyue, Cao Bobo, Ma Jing, Yu Zhi-Wu
MOE Key Laboratory of Bioorganic Phosphorous Chemistry and Chemical Biology, Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China.
Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, P. R. China.
J Phys Chem Lett. 2024 May 16;15(19):5047-5055. doi: 10.1021/acs.jpclett.4c00641. Epub 2024 May 3.
In this study, we analyzed the species in a model electrolyte consisting of a lithium salt, lithium bis(trifluoromethane sulfone)imide (LiTFSI), and a widely used neutral solvent propylene carbonate (PC) with excess infrared (IR) spectroscopy, ab initio molecular dynamics simulations (AIMD), and quantum chemical calculations. Complexing species including the charged ones [Li(PC), TFSI, TFSI(PC), TFSI(PC), and Li(TFSI)] are identified in the electrolyte. Quantum chemical calculations show strong Li···O(PC) interaction, which suggests that Li would transport in the mode of solvation-carriage. However, the interaction energy of each hydrogen bond in TFSI(PC) is very weak, suggesting that TFSI would transport in hopping mode. In addition, the concentration dependences of the relative population of the species were also derived, providing a scenario for the dissolving process of the salt in PC. These in-depth studies provide physical insights into the structural and interactive properties of the electrolyte of lithium-ion batteries.
在本研究中，我们利用红外光谱（IR）、从头算分子动力学模拟（AIMD）和量子化学计算，对由锂盐双（三氟甲烷磺酰）亚胺锂（LiTFSI）和广泛使用的中性溶剂碳酸丙烯酯（PC）组成的模型电解质中的物种进行了分析。在该电解质中识别出了包括带电物种[Li(PC)、TFSI、TFSI(PC)、TFSI(PC)和Li(TFSI)]在内的络合物种。量子化学计算表明存在强烈的Li···O(PC)相互作用，这表明Li将以溶剂化运载的方式传输。然而，TFSI(PC)中每个氢键的相互作用能非常弱，这表明TFSI将以跳跃模式传输。此外，还得出了物种相对丰度的浓度依赖性，为盐在PC中的溶解过程提供了一种情况。这些深入研究为锂离子电池电解质的结构和相互作用特性提供了物理见解。
