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)₄, TFSI^–, TFSI^–(PC), TFSI^–(PC)₂, and Li(TFSI)₂^–] 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.

中文翻译：

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含有 LiTFSI 和碳酸丙烯酯的锂离子电池电解质的原位形态分析

在这项研究中，我们利用过量红外 (IR) 光谱从头开始分析了由锂盐、双（三氟甲磺酰亚胺）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质。分子动力学模拟（AIMD）和量子化学计算。在电解液中鉴定出络合物质，包括带电物质[Li ⁺ (PC) ₄、TFSI ^–、TFSI ^– (PC)、TFSI ^– (PC) ₂和Li(TFSI) ₂ ^– ]。量子化学计算显示出强烈的Li ⁺ ···O(PC) 相互作用，这表明Li ⁺将以溶剂化运输的方式运输。然而，TFSI ^- (PC)中每个氢键的相互作用能非常弱，表明 TFSI ^-将以跳跃模式传输。此外，还导出了物种相对种群的浓度依赖性，为盐在 PC 中的溶解过程提供了情景。这些深入的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。