Simulation study of the solvation structure and ion migration behavior in localized high-concentration electrolytes

doi:10.19799/j.cnki.2095-4239.2025.0120

Abstract

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

CLC Number:

TM 912

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.

Figures/Tables 6

Table 1

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References 26

[1]	陆洋, 闫帅帅, 马骁, 等. 低温锂电池电解液的研究与应用[J]. 储能科学与技术, 2024, 13(7): 2224-2242. DOI: 10.19799/j.cnki.2095-4239. 2024.0313.
	LU Y, YAN S S, MA X, et al. Low-temperature electrolytes and their application in lithium batteries[J]. Energy Storage Science and Technology, 2024, 13(7): 2224-2242. DOI: 10.19799/j.cnki.2095-4239.2024.0313.
[2]	DIEDERICHSEN K M, MCSHANE E J, MCCLOSKEY B D. Promising routes to a high Li⁺ transference number electrolyte for lithium ion batteries[J]. ACS Energy Letters, 2017, 2(11): 2563-2575. DOI: 10.1021/acsenergylett.7b00792.
[3]	ZHOU P, ZHANG X K, XIANG Y, et al. Strategies to enhance Li⁺ transference number in liquid electrolytes for better lithium batteries[J]. Nano Research, 2023, 16(6): 8055-8071. DOI: 10. 1007/s12274-022-4833-1.
[4]	YAO N, YU L G, FU Z H, et al. Probing the origin of viscosity of liquid electrolytes for lithium batteries[J]. Angewandte Chemie International Edition, 2023, 62(41): e202305331. DOI: 10.1002/anie. 202305331.
[5]	CHEN J E, ZHANG H, FANG M M, et al. Design of localized high-concentration electrolytes via donor number[J]. ACS Energy Letters, 2023, 8(4): 1723-1734. DOI: 10.1021/acsenergylett.3c00004.
[6]	REN F H, LI Z D, CHEN J H, et al. Solvent-diluent interaction-mediated solvation structure of localized high-concentration electrolytes[J]. ACS Applied Materials & Interfaces, 2022, 14(3): 4211-4219. DOI: 10.1021/acsami.1c21638.
[7]	PARK E, PARK J, LEE K, et al. Exploiting the steric effect and low dielectric constant of 1,2-dimethoxypropane for 4.3 V lithium metal batteries[J]. ACS Energy Letters, 2023, 8(1): 179-188.
[8]	HOSSAIN M J, WU Q S, MARIN BERNARDEZ E J, et al. The relationship between ionic conductivity and solvation structures of localized high-concentration fluorinated electrolytes for lithium-ion batteries[J]. The Journal of Physical Chemistry Letters, 2023, 14(34): 7718-7731. DOI: 10.1021/acs.jpclett.3c01453.
[9]	PEREZ BELTRAN S, CAO X, ZHANG J G, et al. Influence of diluent concentration in localized high concentration electrolytes: Elucidation of hidden diluent-Li⁺ interactions and Li⁺ transport mechanism[J]. Journal of Materials Chemistry A, 2021, 9(32): 17459-17473. DOI: 10.1039/D1TA04737J.
[10]	EFAW C M, WU Q S, GAO N, et al. Localized high-concentration electrolytes get more localized through micelle-like structures[J]. Nature Materials, 2023, 22(12): 1531-1539. DOI: 10.1038/s41563-023-01700-3.
[11]	CAO X, ZOU L F, MATTHEWS B E, et al. Optimization of fluorinated orthoformate based electrolytes for practical high-voltage lithium metal batteries[J]. Energy Storage Materials, 2021, 34: 76-84. DOI: 10.1016/j.ensm.2020.08.035.
[12]	LI Q, LIU G, CHENG H R, et al. Low-temperature electrolyte design for lithium-ion batteries: Prospect and challenges[J]. Chemistry-A European Journal, 2021, 27(64): 15842-15865. DOI: 10.1002/chem.202101407.
[13]	CAO X, JIA H, XU W, et al. Review—Localized high-concentration electrolytes for lithium batteries[J]. Journal of the Electrochemical Society, 2021, 168(1): 010522. DOI: 10.1149/1945-7111/abd60e.
[14]	MARTÍNEZ L, ANDRADE R, BIRGIN E G, et al. PACKMOL: A package for building initial configurations for molecular dynamics simulations[J]. Journal of Computational Chemistry, 2009, 30(13): 2157-2164. DOI: 10.1002/jcc.21224.
[15]	BERENDSEN H J C, VAN DER SPOEL D, VAN DRUNEN R. GROMACS: A message-passing parallel molecular dynamics implementation[J]. Computer Physics Communications, 1995, 91(1/2/3): 43-56. DOI: 10.1016/0010-4655(95)00042-E.
[16]	DODDA L S, CABEZA DE VACA I, TIRADO-RIVES J, et al. LigParGen web server: An automatic OPLS-AA parameter generator for organic ligands[J]. Nucleic Acids Research, 2017, 45(W1): W331-W336. DOI: 10.1093/nar/gkx312.
[17]	PODGORŠEK A, SALAS G, CAMPBELL P S, et al. Influence of ionic association, transport properties, and solvation on the catalytic hydrogenation of 1,3-cyclohexadiene in ionic liquids[J]. The Journal of Physical Chemistry B, 2011, 115(42): 12150-12159. DOI: 10.1021/jp206619c.
[18]	NOSÉ S. A unified formulation of the constant temperature molecular dynamics methods[J]. The Journal of Chemical Physics, 1984, 81(1): 511-519. DOI: 10.1063/1.447334.
[19]	BERENDSEN H J C, POSTMA J P M, VAN GUNSTEREN W F, et al. Molecular dynamics with coupling to an external bath[J]. The Journal of Chemical Physics, 1984, 81(8): 3684-3690. DOI: 10.1063/1.448118.
[20]	HUMPHREY W, DALKE A, SCHULTEN K. VMD: Visual molecular dynamics[J]. Journal of Molecular Graphics, 1996, 14(1): 33-38. DOI: 10.1016/0263-7855(96)00018-5.
[21]	WANG Y K, LI Z M, HOU Y P, et al. Emerging electrolytes with fluorinated solvents for rechargeable lithium-based batteries[J]. Chemical Society Reviews, 2023, 52(8): 2713-2763. DOI: 10. 1039/D2CS00873D.
[22]	YAMADA Y, WANG J H, KO S, et al. Advances and issues in developing salt-concentrated battery electrolytes[J]. Nature Energy, 2019, 4(4): 269-280. DOI: 10.1038/s41560-019-0336-z.
[23]	SELF J, FONG K D, PERSSON K A. Transport in superconcentrated LiPF₆ and LiBF₄/propylene carbonate electrolytes[J]. ACS Energy Letters, 2019, 4(12): 2843-2849.
[24]	DOKKO K, WATANABE D, UGATA Y, et al. Direct evidence for Li ion hopping conduction in highly concentrated sulfolane-based liquid electrolytes[J]. The Journal of Physical Chemistry B, 2018, 122(47): 10736-10745. DOI: 10.1021/acs.jpcb.8b09439.
[25]	YAO N, CHEN X, SUN S Y, et al. Identifying the lithium bond and lithium ionic bond in electrolytes[J]. Chem, 2025, 11(1): 102254. DOI: 10.1016/j.chempr.2024.07.016.
[26]	何一涛, 丁飞, 林立, 等. 电极界面浓差极化对锂金属沉积的影响[J]. 物理化学学报, 2021, 37(2): 157-163. DOI: 10.3866/PKU.WHXB202009001.
	HE Y T, DING F, LIN L, et al. Influence of interfacial concentration polarization on lithium metal electrodeposition[J]. Acta Physico-Chimica Sinica, 2021, 37(2): 157-163. DOI: 10.3866/PKU.WHXB202009001.

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