Analyzing the internal interface in localized high-concentration electrolytes.

IF 3.1 2区 化学 Q3 CHEMISTRY, PHYSICAL
Anne Hockmann, Monika Schönhoff, Diddo Diddens
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引用次数: 0

Abstract

We present molecular dynamics simulations on localized high-concentration electrolytes (LHCE) based on the conducting salt lithium bis(fluorosulfonyl)imide (LiFSI) or lithium bis(trifluoromethanesulfonyl)imide dissolved in the solvent 1,2-dimethoxyethane and diluted to two different degrees with the diluent 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether. Due to the immiscibility of the conducting salt phase (salt + solvent) and the diluent phase, LHCEs feature a complex microstructure of two phases forming an internal interface. In this study, we not only investigate the lithium coordination structure in the conducting salt phase but also the size and composition of its interface to the diluent phase by Voronoi tessellations. Furthermore, we investigate the influence on the ion transport by evaluating Onsager coefficients. We show that an LHCE containing the surface-active anion TFSI- creates an anion-rich internal interface, leading to enhanced ion dissociation and anticorrelated ion movement. On the other hand, the smaller FSI- anion with a more localized charge distribution and less amphiphilic character shows no enrichment at the internal interface, but rather a depletion. By increasing LiFSI concentration, we even observe a solvent-rich internal interface due to a large and branched Li-anion network. Furthermore, the less diffuse interface and enlarged Li-anion network lead to lower ion-ion anticorrelations and a stronger convective flux of the conducting salt phase, which is compensated by a flux of the diluent phase, especially in the higher concentrated LiFSI based LHCE.

局部高浓度电解液内部界面分析。
基于导电盐锂二(氟磺酰基)亚胺(LiFSI)或锂二(三氟甲烷磺酰基)亚胺溶解于溶剂1,2-二甲氧基乙烷中,并用稀释剂1,1,2,2-四氟乙基-2,2,3,3-四氟丙基醚稀释至两种不同程度,对局域化高浓度电解质(LHCE)进行了分子动力学模拟。由于导电盐相(盐+溶剂)和稀释相的不混溶,LHCEs具有两相形成内部界面的复杂微观结构。在这项研究中,我们不仅研究了锂在导电盐相中的配位结构,而且通过Voronoi镶嵌研究了其与稀释相界面的大小和组成。此外,我们还通过计算Onsager系数来研究离子输运的影响。我们发现含有表面活性阴离子TFSI-的LHCE产生了一个富含阴离子的内部界面,导致离子解离和反相关离子运动增强。另一方面,较小的FSI-阴离子具有更局域化的电荷分布和更少的两亲性,在内部界面处没有富集,而是耗尽。通过增加LiFSI浓度,我们甚至观察到由于一个大的分支的锂阴离子网络,一个富含溶剂的内部界面。此外,较少的扩散界面和扩大的锂阴离子网络导致离子-离子反相关关系降低和导电盐相的对流通量增强,这被稀释相的通量补偿,特别是在高浓度的LiFSI基LHCE中。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Journal of Chemical Physics
Journal of Chemical Physics 物理-物理:原子、分子和化学物理
CiteScore
7.40
自引率
15.90%
发文量
1615
审稿时长
2 months
期刊介绍: The Journal of Chemical Physics publishes quantitative and rigorous science of long-lasting value in methods and applications of chemical physics. The Journal also publishes brief Communications of significant new findings, Perspectives on the latest advances in the field, and Special Topic issues. The Journal focuses on innovative research in experimental and theoretical areas of chemical physics, including spectroscopy, dynamics, kinetics, statistical mechanics, and quantum mechanics. In addition, topical areas such as polymers, soft matter, materials, surfaces/interfaces, and systems of biological relevance are of increasing importance. Topical coverage includes: Theoretical Methods and Algorithms Advanced Experimental Techniques Atoms, Molecules, and Clusters Liquids, Glasses, and Crystals Surfaces, Interfaces, and Materials Polymers and Soft Matter Biological Molecules and Networks.
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