Transport properties of imidazolium based ionic liquid electrolytes from molecular dynamics simulations

Yang, Moon Young; Merinov, Boris V.; Zybin, Sergey V.; Goddard, William A.; Mok, Eun Kyung; Hah, Hoe Jin; Han, Hyea Eun; Choi, Young Cheol; Kim, Seung Ha

doi:10.1002/elsa.202100007

Cited by 6 publications

(2 citation statements)

References 42 publications

(103 reference statements)

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“…The slowdown of the dynamics in ionic liquids containing lithium cations has been related to a modification of the structure of the liquid, through the solvation of lithium [3,52,56,57]. In the case of TFSI anion, lithium cation interacts more strongly with the oxygen [58,59] and is surrounded by approximately three TFSI. Experimentally, the solvation of lithium cation by TFSI anion, is expressed by the evolution of D TFSI that tends to come closer to D Li when Li + concentration is increased.…”

Section: The Diffusion At the Micrometer Scale Was Investigated For [...mentioning

confidence: 99%

NMR investigation of multi-scale dynamics in ionic liquids containing Li+ and La3+: from vehicular to hopping transport mechanism

Karé,

De Souza Braga Neto,

Rigaud

et al. 2024

Preprint

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The dynamics in mixtures of ionic liquid and monoatomic cations has been studied at different time scales ranging from the nanosecond up to the second. The mixtures were composed of cholinium bis(trifluoromethanesulfonyl)imide ([Chol][TFSI]) and LiTFSI, with LiTFSI mole fraction, LiTFSI, spanning from 0 to 0.5 (saturated solution), and [Chol][TFSI] and La(TFSI)3 with 0< x{La(TFSI)3}} < 0.12. The translational self-diffusion coefficients of Chol+, TFSI- and Li+ have been measured, along with NMR their relaxation times at various magnetic fields, in order to decipher the intertwined dynamics between the ions, and to reveal how the local dynamics impact the long range translational diffusion. When the concentrations of lithium and lanthanum are increased in the liquid, the long range dynamics of all the ions drop. In the case of LiTFSI, the self-diffusion coefficient of lithium becomes higher than the one of TFSI at high concentration, revealing a change in lithium transport mechanisms. The NMR relaxation data confirm this change, showing a clearer transition at x{LiTFSI}=0.15. It is interpreted as a change from a vehicular transport mechanism of the lithium below x{LiTFSI}=0.15 to a hopping mechanism above. A similar crossover seems to occur in the lanthanum solutions. It is suspected that the hydroxyl group of the organic cation is involved in this phenomenon.

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Section: The Diffusion At the Micrometer Scale Was Investigated For [...mentioning

confidence: 99%

NMR investigation of multi-scale dynamics in ionic liquids containing Li+ and La3+: from vehicular to hopping transport mechanism

Karé,

De Souza Braga Neto,

Rigaud

et al. 2024

Preprint

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“…There are a handful of studies that examine the effects of EEFs on the bulk structure and transport properties of ILs. − Umecky et al used pulsed gradient spin–echo NMR to measure diffusion, ion mobilities and estimated viscosities of various imidazolium-based ILs including [C 2 C 1 im][NTf 2 ] under various EEFs. They suggested that the EEFs cause the alignment of ions in the liquid phase and found that the observed viscosity depends on the degree of ion orientation, which is associated with the polarization degree of the ionic species comprising the salts .…”

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Simulation of the Influence of External Electric Fields on the Glass Transition Temperature of the Ionic Liquid 1-Ethyl-3-methylimidazolium Bis(trifluoromethylsulfonyl)imide

Carmona Esteva,

Zhang,

Colón

et al. 2023

J. Phys. Chem. B

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We present the results of molecular dynamics simulations of the ionic liquid (IL) 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [C2C1im][NTf2] in the presence of external electric fields (EEFs) of varying strengths to understand the effects of EEFs on the glass transition temperature T g. We compute T g with an automated and objective method and observe a depression in T g when cooling the IL within an EEF above a critical strength. The effect is reversible, and glasses prepared with EEFs recover their original zero-field T g when heated. By examining the dynamics and structure of the liquid phase, we find that the EEF lowers the activation energy for diffusion, reducing the energetic barrier for movement and consequently T g. We show that the effect can be leveraged to drive an electrified nonvapor compression refrigeration cycle.

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Characterization of the Solid Electrolyte Interphase at the Li Metal–Ionic Liquid Interface

Yang

Zybin

Das

et al. 2022

Advanced Energy Materials

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energy density (372 mAh g −1 ), which is not sufficient to meet the increasing energy density demand for electric vehicles, portable electronic devices, and large-scale energy storage systems. [4,5] This motivates reviving Li-metal as a prospective anode material that could provide more than tenfold higher capacity (3860 mAh g −1 ), low electrochemical potential (−3.04 V vs the standard hydrogen electrode, SHE), and low gravimetric density (0.534 g cm −3 ). [6,7] These advantages make application of Li anode batteries indispensable for next generation energy-storage devices, such as Li-S and Li-air batteries.Despite the great potential of high energy density batteries, commercialization of Li-metal batteries (LMBs) is hindered by poor cycling performance and severe safety issues originating from the high reactivity of Limetal. [7] In addition to dendrite growth, Li reacts instantaneously with electrolytes, resulting in formation of a chemically unstable and mechanically fragile surface film referred to as the solid electrolyte interphase (SEI). [8,9] Since the SEI plays an important role in battery stability and performance, extensive research has been conducted to investigate and improve SEI properties, including optimization of electrolyte compositions, [10] application of solid electrolytes, [11] and construction of artificial SEI layers. [12] In addition, significant efforts have been made to investigate the SEI compositions and morphology using such techniques as X-ray photo electron spectroscopy, [13] mass spectrometry, [14] and nuclear magnetic resonance. [15] However, the atomistic structure and properties of the electrode/ electrolyte interface, particularly the evolution of SEI growth, remain poorly understood. The complexity of the chemical and electrochemical reactions at the interface makes it most difficult to carry out direct experimental measurements of the SEI formation process beyond chemical composition to provide the detailed information needed to develop improved materials and devices.Given the great difficulties for experimental assessment of the atomistic details of the SEI, we have applied quantum mechanics (QM) based molecular dynamics (MD) approaches to provide fundamental information about the reactions at the interface between Li-metal and electrolyte molecules at the atomistic level. [16][17][18] However such QM studies are generally limited to <300 atoms and <100 picoseconds (ps) due to extremely high computational costs, limiting applications of QM-MD to very simplistic studies at the 2-3 nm scale of the The solid electrolyte interphase (SEI) forms on electrode surfaces from decomposition of the electrolyte. However, there is almost no atomistic detail of SEI formation on Li metal anode, a major obstacle in understanding the highly complex battery electrochemistry sufficiently to design high performance batteries. Herein, a realistic atomistic model (39 000 atoms) for the SEI formation at the interface between the Li metal anode and ionic liquid electrolyte using reactive molecular ...

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Transport properties of imidazolium based ionic liquid electrolytes from molecular dynamics simulations

Cited by 6 publications

References 42 publications

NMR investigation of multi-scale dynamics in ionic liquids containing Li+ and La3+: from vehicular to hopping transport mechanism

NMR investigation of multi-scale dynamics in ionic liquids containing Li+ and La3+: from vehicular to hopping transport mechanism

Molecular Dynamics Simulation of the Influence of External Electric Fields on the Glass Transition Temperature of the Ionic Liquid 1-Ethyl-3-methylimidazolium Bis(trifluoromethylsulfonyl)imide

Characterization of the Solid Electrolyte Interphase at the Li Metal–Ionic Liquid Interface

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