局域高浓度电解质溶剂化结构与离子迁移行为模拟研究

doi:10.19799/j.cnki.2095-4239.2025.0120

摘要/Abstract

摘要：

针对电解质分子间相互作用对Li⁺输运行为影响尚不明确的问题，本工作通过分子动力学(MD)模拟研究了局域高浓度电解质(LHCE)的非均相结构。以1, 1, 2, 2-四氟乙基-2, 2, 3, 3-四氟丙基醚(D2)作为稀释剂，构建了LHCE模型，并深入分析了溶剂分子与稀释剂之间的相互作用，以探讨其对Li⁺配位结构和迁移行为的影响。研究结果表明，Li⁺通过重复的离子解离/缔合跳跃机制进行迁移，并通过D2-CIP(阴离子配位单个Li⁺)界面处加速迁移，D2分子充当了快速传导路径的载体。此外，发现LiFSI∶DME∶D2(摩尔比)为1∶1.2∶2的电解质配方，存在离子迁移速率极点(转折)效应，并显著增强了锂盐的抗还原性及离子迁移速率。该研究为开发高浓度电解质(HCE)的新型稀释策略提供了重要的理论依据。

关键词: 局域高浓度电解质, 分子动力学, 溶剂化结构, 离子迁移行为

Abstract:

The influence of intermolecular interactions on Li⁺ transport in electrolytes remains insufficiently understood. In this study, molecular dynamics simulations were conducted to investigate the heterogeneous structure of localized high-concentration electrolytes, using 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (D2) as a diluent. The interactions among solvent molecules and the diluent were analyzed to evaluate their effects on Li⁺ coordination structure and migration behavior. The results show that Li⁺ migrates via repeated ion dissociation/association hopping and exhibits accelerated migration across the D2-CIP (contact ion pair) interface, with D2 molecules serving as carriers along fast transport pathways. Additionally, an electrolyte with a molar ratio of LiFSI∶DME∶D2 = 1∶1.2∶2 exhibited an ion migration rate extremum, significantly enhancing both the reduction resistance of the lithium salt and the ion migration rate. This work offers important theoretical insights into the development of advanced dilution strategies for high-concentration electrolytes.

Key words: localized high-concentration electrolytes, molecular dynamics, solvation structure, ion migration behavior

中图分类号:

TM 912

庞超, 丁爽, 张晓琨, 向勇. 局域高浓度电解质溶剂化结构与离子迁移行为模拟研究[J]. 储能科学与技术, 2025, 14(8): 3207-3215.

Chao PANG, Shuang DING, Xiaokun ZHANG, Yong XIANG. Simulation study of the solvation structure and ion migration behavior in localized high-concentration electrolytes[J]. Energy Storage Science and Technology, 2025, 14(8): 3207-3215.

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项目	体系(摩尔比)	缩写	LiFSI	DME	D2
LCE	LiFSI-9DME	LCE	60	540	—

HCE	LiFSI-1.2DME	HCE1	200	240	—
HCE	LiFSI-1.5DME	HCE2	186	279	—

LHCE	LiFSI-1.2DME-D2	LHCE1	115	138	115
	LiFSI-1.5DME-D2	LHCE2	110	165	110
	LiFSI-1.2DME-2D2	LHCE3	80	96	160
	LiFSI-1.5DME-2D2	LHCE4	78	118	156
	LiFSI-1.2DME-6D2	LHCE5	35	42	210
	LiFSI-1.5DME-6D2	LHCE6	32	48	192