Solvation Structure and Dynamics of Mg(TFSI)2 Aqueous Electrolyte

Zhou Yu; Taylor R. Juran; Xinyi Liu; Kee Sung Han; Hui Wang; Karl T. Mueller; Lin Ma; Kang Xu; Tao Li; Larry A. Curtiss; Lei Cheng

doi:10.1002/eem2.12174

Solvation Structure and Dynamics of Mg(TFSI)₂ Aqueous Electrolyte

Zhou Yu
, Taylor R. Juran
, Xinyi Liu
, Kee Sung Han
, Hui Wang
, Karl T. Mueller
, Lin Ma
, Kang Xu
, Tao Li
, Larry A. Curtiss
, Lei Cheng

Research output: Contribution to journal › Article › peer-review

34 Scopus citations

Abstract

Using ab initio molecular dynamics (AIMD) simulations, classical molecular dynamics (CMD) simulations, small-angle X-ray scattering (SAXS), and pulsed-field gradient nuclear magnetic resonance (PFG-NMR), the solvation structure and ion dynamics of magnesium bis(trifluoromethanesulfonyl)imide (Mg(TFSI)₂) aqueous electrolyte at 1, 2, and 3 m concentrations are investigated. From AIMD and CMD simulations, the first solvation shell of an Mg²⁺ ion is found to be composed of six water molecules in an octahedral configuration and the solvation shell is rather rigid. The TFSI⁻ ions prefer to stay in the second solvation shell and beyond. Meanwhile, the comparable diffusion coefficients of positive and negative ions in Mg(TFSI)₂ aqueous electrolytes have been observed, which is mainly due to the formation of the stable [Mg(H₂O)₆]²⁺ complex, and, as a result, the increased effective Mg ion size. Finally, the calculated correlated transference numbers are lower than the uncorrelated ones even at the low concentration of 2 and 3 m, suggesting the enhanced correlations between ions in the multivalent electrolytes. This work provides a molecular-level understanding of how the solvation structure and multivalency of the ion affect the dynamics and transport properties of the multivalent electrolyte, providing insight for rational designs of electrolytes for improved ion transport properties.

Original language	English
Pages (from-to)	295-304
Number of pages	10
Journal	Energy and Environmental Materials
Volume	5
Issue number	1
DOIs	https://doi.org/10.1002/eem2.12174
State	Published - Jan 2022
Externally published	Yes

Funding

This research was supported by the Joint Center for Energy Storage Research (JCESR), a U.S. Department of Energy, Energy Innovation Hub. The submitted manuscript has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (“Argonne”). Argonne, a U.S. Department of Energy Office of Science laboratory, is operated under Contract no. DE‐AC02‐06CH11357. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility, operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE‐AC02‐06CH11357. The PFG‐NMR measurements were performed at the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility, sponsored by the DOE's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). We acknowledge Dr. Yuyue Zhao for the density measurement of Mg(TFSI) aqueous electrolytes. We gratefully acknowledge the computing resources provided on Bebop, a high‐performance computing cluster, operated by the Laboratory Computing Resource Center at Argonne National Laboratory. 2 This research was supported by the Joint Center for Energy Storage Research (JCESR), a U.S. Department of Energy, Energy Innovation Hub. The submitted manuscript has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (?Argonne?). Argonne, a U.S. Department of Energy Office of Science laboratory, is operated under Contract no. DE-AC02-06CH11357. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility, operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. The PFG-NMR measurements were performed at the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility, sponsored by the DOE's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory (PNNL). We acknowledge Dr. Yuyue Zhao for the density measurement of Mg(TFSI)2 aqueous electrolytes. We gratefully acknowledge the computing resources provided on Bebop, a high-performance computing cluster, operated by the Laboratory Computing Resource Center at Argonne National Laboratory. The authors declare no conflict of interest.

Access to Document

10.1002/eem2.12174

Cite this

@article{f4a2d0f82f67478caa9e281f69ba8277,

title = "Solvation Structure and Dynamics of Mg(TFSI)2 Aqueous Electrolyte",

abstract = "Using ab initio molecular dynamics (AIMD) simulations, classical molecular dynamics (CMD) simulations, small-angle X-ray scattering (SAXS), and pulsed-field gradient nuclear magnetic resonance (PFG-NMR), the solvation structure and ion dynamics of magnesium bis(trifluoromethanesulfonyl)imide (Mg(TFSI)2) aqueous electrolyte at 1, 2, and 3 m concentrations are investigated. From AIMD and CMD simulations, the first solvation shell of an Mg2+ ion is found to be composed of six water molecules in an octahedral configuration and the solvation shell is rather rigid. The TFSI− ions prefer to stay in the second solvation shell and beyond. Meanwhile, the comparable diffusion coefficients of positive and negative ions in Mg(TFSI)2 aqueous electrolytes have been observed, which is mainly due to the formation of the stable [Mg(H2O)6]2+ complex, and, as a result, the increased effective Mg ion size. Finally, the calculated correlated transference numbers are lower than the uncorrelated ones even at the low concentration of 2 and 3 m, suggesting the enhanced correlations between ions in the multivalent electrolytes. This work provides a molecular-level understanding of how the solvation structure and multivalency of the ion affect the dynamics and transport properties of the multivalent electrolyte, providing insight for rational designs of electrolytes for improved ion transport properties.",

author = "Zhou Yu and Juran, \{Taylor R.\} and Xinyi Liu and Han, \{Kee Sung\} and Hui Wang and Mueller, \{Karl T.\} and Lin Ma and Kang Xu and Tao Li and Curtiss, \{Larry A.\} and Lei Cheng",

note = "Publisher Copyright: {\textcopyright} 2021 Zhengzhou University",

year = "2022",

month = jan,

doi = "10.1002/eem2.12174",

language = "English",

volume = "5",

pages = "295--304",

journal = "Energy and Environmental Materials",

issn = "2575-0348",

publisher = "Wiley Open Access",

number = "1",

}

TY - JOUR

T1 - Solvation Structure and Dynamics of Mg(TFSI)2 Aqueous Electrolyte

AU - Yu, Zhou

AU - Juran, Taylor R.

AU - Liu, Xinyi

AU - Han, Kee Sung

AU - Wang, Hui

AU - Mueller, Karl T.

AU - Ma, Lin

AU - Xu, Kang

AU - Li, Tao

AU - Curtiss, Larry A.

AU - Cheng, Lei

PY - 2022/1

Y1 - 2022/1

N2 - Using ab initio molecular dynamics (AIMD) simulations, classical molecular dynamics (CMD) simulations, small-angle X-ray scattering (SAXS), and pulsed-field gradient nuclear magnetic resonance (PFG-NMR), the solvation structure and ion dynamics of magnesium bis(trifluoromethanesulfonyl)imide (Mg(TFSI)2) aqueous electrolyte at 1, 2, and 3 m concentrations are investigated. From AIMD and CMD simulations, the first solvation shell of an Mg2+ ion is found to be composed of six water molecules in an octahedral configuration and the solvation shell is rather rigid. The TFSI− ions prefer to stay in the second solvation shell and beyond. Meanwhile, the comparable diffusion coefficients of positive and negative ions in Mg(TFSI)2 aqueous electrolytes have been observed, which is mainly due to the formation of the stable [Mg(H2O)6]2+ complex, and, as a result, the increased effective Mg ion size. Finally, the calculated correlated transference numbers are lower than the uncorrelated ones even at the low concentration of 2 and 3 m, suggesting the enhanced correlations between ions in the multivalent electrolytes. This work provides a molecular-level understanding of how the solvation structure and multivalency of the ion affect the dynamics and transport properties of the multivalent electrolyte, providing insight for rational designs of electrolytes for improved ion transport properties.

AB - Using ab initio molecular dynamics (AIMD) simulations, classical molecular dynamics (CMD) simulations, small-angle X-ray scattering (SAXS), and pulsed-field gradient nuclear magnetic resonance (PFG-NMR), the solvation structure and ion dynamics of magnesium bis(trifluoromethanesulfonyl)imide (Mg(TFSI)2) aqueous electrolyte at 1, 2, and 3 m concentrations are investigated. From AIMD and CMD simulations, the first solvation shell of an Mg2+ ion is found to be composed of six water molecules in an octahedral configuration and the solvation shell is rather rigid. The TFSI− ions prefer to stay in the second solvation shell and beyond. Meanwhile, the comparable diffusion coefficients of positive and negative ions in Mg(TFSI)2 aqueous electrolytes have been observed, which is mainly due to the formation of the stable [Mg(H2O)6]2+ complex, and, as a result, the increased effective Mg ion size. Finally, the calculated correlated transference numbers are lower than the uncorrelated ones even at the low concentration of 2 and 3 m, suggesting the enhanced correlations between ions in the multivalent electrolytes. This work provides a molecular-level understanding of how the solvation structure and multivalency of the ion affect the dynamics and transport properties of the multivalent electrolyte, providing insight for rational designs of electrolytes for improved ion transport properties.

UR - https://www.scopus.com/pages/publications/85101043879

U2 - 10.1002/eem2.12174

DO - 10.1002/eem2.12174

M3 - Article

AN - SCOPUS:85101043879

SN - 2575-0348

VL - 5

SP - 295

EP - 304

JO - Energy and Environmental Materials

JF - Energy and Environmental Materials

IS - 1

ER -

Solvation Structure and Dynamics of Mg(TFSI)₂ Aqueous Electrolyte

Abstract

Funding

Access to Document

Other files and links

Fingerprint

Cite this