Title: Ion Pairing and Redissociaton in Low-Permittivity Electrolytes for Multivalent Battery Applications

Abstract

Detailed speciation of electrolytes as a function of chemical system and concentration provides the foundation for understanding bulk transport as well as possible decomposition mechanisms. In particular, multivalent electrolytes have shown a strong coupling between anodic stability and solvation structure. Furthermore, solvents that are found to exhibit reasonable stability against alkaline-earth metals generally exhibit low permittivity, which typically increases the complexity of the electrolyte species. To improve our understanding of ionic population and associated transport in these important classes of electrolytes, the speciation of Mg(TFSI)2 in monoglyme and diglyme systems is studied via a multiscale thermodynamic model using first-principles calculations for ion association and molecular dynamics simulations for dielectric properties. The results are then compared to Raman and dielectric relaxation spectroscopies, which independently confirm the modeling insights. We find that the significant presence of free ions in the low-permittivity glymes in the concentration range from 0.02 to 0.6 M is well-explained by the low-permittivity redissociation hypothesis. Here, salt speciation is largely dictated by long-range electrostatics, which includes permittivity increases due to polar contact ion pairs. The present results suggest that other low-permittivity multivalent electrolytes may also reach high conductivities as a result of redissociation.

Authors:

Self, Julian  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-5486-9559"

Hahn, Nathan T.  ^[2];

• Search DOE PAGES for author "Hahn, Nathan T."
• Search DOE PAGES for ORCID "0000-0001-6187-4068"

Fong, Kara D.  ^[3];

• Search DOE PAGES for author "Fong, Kara D."
• Search DOE PAGES for ORCID "0000-0002-0711-097X"

McClary, Scott A.  ^[2];

• Search DOE PAGES for author "McClary, Scott A."
• Search DOE PAGES for ORCID "0000-0001-9011-1043"

Zavadil, Kevin R.  ^[2];

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• Search DOE PAGES for ORCID "0000-0002-3791-424X"

Persson, Kristin A.  ^[1]

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• Search DOE PAGES for ORCID "0000-0003-2495-5509"

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+ Show Author Affiliations

1. Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Engineering; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
3. Univ. of California, Berkeley, CA (United States). Dept. of Chemical and Biomolecular Engineering; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

Publication Date:

Thu Feb 20 00:00:00 EST 2020

Research Org.:

Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1630283

Alternate Identifier(s):

OSTI ID: 1765557

Report Number(s):

SAND-2020-5025J
Journal ID: ISSN 1948-7185; 686057

Grant/Contract Number:  

AC04-94AL85000; AC02-05CH11231

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Physical Chemistry Letters

Additional Journal Information:

Journal Volume: 11; Journal Issue: 6; Journal ID: ISSN 1948-7185

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

English

Subject:

25 ENERGY STORAGE