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Title: The Interplay between Salt Association and the Dielectric Properties of Low Permittivity Electrolytes: The Case of LiPF 6 and LiAsF 6 in Dimethyl Carbonate

Abstract

Here, we present evidence that the dielectric constant of an electrolyte solution can be effectively used to infer the association regime of the salt species from computational methods. As case studies, we consider the low dielectric constant solvent dimethyl carbonate with LiAsF 6 and LiPF 6 salts at low concentrations. Using both quantum “ab initio” methods as well classical molecular dynamics simulations, we elucidate the salt’s contribution to the dielectric constant as well as the dipolar relaxation times, which act as quantitative signatures. By comparing to previously published measurements, we provide strong evidence for the presence of contact-ion pairs at these low concentrations. Interestingly, these ion pairs increase the dielectric constant of the solution, allowing for significantly improved ionic conductivity as a function of salt concentrations. We also discuss the role of multimeric equilibrium species as contributors to the functional properties of designer electrolytes, such as dielectric properties of the solution and ionic conductivity.

Authors:
ORCiD logo [1];  [2]; ORCiD logo [3];  [4]
  1. Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Engineering; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Energy Technologies Area
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Energy Technologies Area; Univ. of California, Berkeley, CA (United States). Dept. of Applied Science and Technology
  3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Energy Technologies Area
  4. Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Engineering, and Dept. of Applied Science and Technology; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Energy Technologies Area
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1483679
Grant/Contract Number:  
AC02-06CH11357; AC02-05CH11231
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. C
Additional Journal Information:
Journal Volume: 122; Journal Issue: 4; Journal ID: ISSN 1932-7447
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Self, Julian, Wood, Brandon M., Rajput, Nav Nidhi, and Persson, Kristin A. The Interplay between Salt Association and the Dielectric Properties of Low Permittivity Electrolytes: The Case of LiPF6 and LiAsF6 in Dimethyl Carbonate. United States: N. p., 2017. Web. doi:10.1021/acs.jpcc.7b11060.
Self, Julian, Wood, Brandon M., Rajput, Nav Nidhi, & Persson, Kristin A. The Interplay between Salt Association and the Dielectric Properties of Low Permittivity Electrolytes: The Case of LiPF6 and LiAsF6 in Dimethyl Carbonate. United States. doi:10.1021/acs.jpcc.7b11060.
Self, Julian, Wood, Brandon M., Rajput, Nav Nidhi, and Persson, Kristin A. Wed . "The Interplay between Salt Association and the Dielectric Properties of Low Permittivity Electrolytes: The Case of LiPF6 and LiAsF6 in Dimethyl Carbonate". United States. doi:10.1021/acs.jpcc.7b11060. https://www.osti.gov/servlets/purl/1483679.
@article{osti_1483679,
title = {The Interplay between Salt Association and the Dielectric Properties of Low Permittivity Electrolytes: The Case of LiPF6 and LiAsF6 in Dimethyl Carbonate},
author = {Self, Julian and Wood, Brandon M. and Rajput, Nav Nidhi and Persson, Kristin A.},
abstractNote = {Here, we present evidence that the dielectric constant of an electrolyte solution can be effectively used to infer the association regime of the salt species from computational methods. As case studies, we consider the low dielectric constant solvent dimethyl carbonate with LiAsF6 and LiPF6 salts at low concentrations. Using both quantum “ab initio” methods as well classical molecular dynamics simulations, we elucidate the salt’s contribution to the dielectric constant as well as the dipolar relaxation times, which act as quantitative signatures. By comparing to previously published measurements, we provide strong evidence for the presence of contact-ion pairs at these low concentrations. Interestingly, these ion pairs increase the dielectric constant of the solution, allowing for significantly improved ionic conductivity as a function of salt concentrations. We also discuss the role of multimeric equilibrium species as contributors to the functional properties of designer electrolytes, such as dielectric properties of the solution and ionic conductivity.},
doi = {10.1021/acs.jpcc.7b11060},
journal = {Journal of Physical Chemistry. C},
number = 4,
volume = 122,
place = {United States},
year = {2017},
month = {12}
}

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Figures / Tables:

Figure 1 Figure 1: Experimentally measured conductivity as a function of salt concentration for LiAsF6 and LiPF6 in DMC.9–11 The bottom rectangles (left to right) illustrate the neat solvent, an electrolyte with only associated salt (with dipole moments drawn as directed arrows), and finally an electrolyte with both associated (arrows) and dissociatedmore » salt (no arrows).« less

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Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.