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Title: Universal Relationship between Conductivity and Solvation-Site Connectivity in Ether-Based Polymer Electrolytes

Abstract

In this paper, we perform a joint experimental and computational study of ion transport properties in a systematic set of linear polyethers synthesized via acyclic diene metathesis (ADMET) polymerization. We measure ionic conductivity, σ, and glass transition temperature, T g, in mixtures of polymer and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt. While T g is known to be an important factor in the ionic conductivity of polymer electrolytes, recent work indicates that the number and proximity of lithium ion solvation sites in the polymer also play an important role, but this effect has yet to be systematically investigated. Here, adding aliphatic linkers to a poly(ethylene oxide) (PEO) backbone lowers T g and dilutes the polar groups; both factors influence ionic conductivity. To isolate these effects, we introduce a two-step normalization scheme. In the first step, Vogel–Tammann–Fulcher (VTF) fits are used to calculate a temperature-dependent reduced conductivity, σ r(T), which is defined as the conductivity of the electrolyte at a fixed value of T – T g. In the second step, we compute a nondimensional parameter f exp, defined as the ratio of the reduced molar conductivity of the electrolyte of interest to that of a reference polymer (PEO) at a fixed saltmore » concentration. We find that f exp depends only on oxygen mole fraction, x 0, and is to a good approximation independent of temperature and salt concentration. Molecular dynamics simulations are performed on neat polymers to quantify the occurrences of motifs that are similar to those obtained in the vicinity of isolated lithium ions. Finally, we show that f exp is a linear function of the simulation-derived metric of connectivity between solvation sites. From the relationship between σ r and f exp we derive a universal equation that can be used to predict the conductivity of ether-based polymer electrolytes at any salt concentration and temperature.« less

Authors:
 [1];  [2];  [3];  [3];  [2];  [3];  [4]
  1. Univ. of California, Berkeley, CA (United States). Dept. of Chemical and Biomolecular Engineering
  2. California Inst. of Technology (CalTech), Pasadena, CA (United States). Division of Chemistry and Chemical Engineering
  3. Cornell Univ., Ithaca, NY (United States). Dept. of Chemistry and Chemical Biology. Baker Lab.
  4. Univ. of California, Berkeley, CA (United States). Dept. of Chemical and Biomolecular Engineering; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Science Division. Environmental Energy Technology Division
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF)
OSTI Identifier:
1474952
Grant/Contract Number:  
AC02-05CH11231; CHE-1335486
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Macromolecules
Additional Journal Information:
Journal Volume: 49; Journal Issue: 14; Journal ID: ISSN 0024-9297
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Pesko, Danielle M., Webb, Michael A., Jung, Yukyung, Zheng, Qi, Miller, Thomas F., Coates, Geoffrey W., and Balsara, Nitash P. Universal Relationship between Conductivity and Solvation-Site Connectivity in Ether-Based Polymer Electrolytes. United States: N. p., 2016. Web. doi:10.1021/acs.macromol.6b00851.
Pesko, Danielle M., Webb, Michael A., Jung, Yukyung, Zheng, Qi, Miller, Thomas F., Coates, Geoffrey W., & Balsara, Nitash P. Universal Relationship between Conductivity and Solvation-Site Connectivity in Ether-Based Polymer Electrolytes. United States. doi:10.1021/acs.macromol.6b00851.
Pesko, Danielle M., Webb, Michael A., Jung, Yukyung, Zheng, Qi, Miller, Thomas F., Coates, Geoffrey W., and Balsara, Nitash P. Fri . "Universal Relationship between Conductivity and Solvation-Site Connectivity in Ether-Based Polymer Electrolytes". United States. doi:10.1021/acs.macromol.6b00851. https://www.osti.gov/servlets/purl/1474952.
@article{osti_1474952,
title = {Universal Relationship between Conductivity and Solvation-Site Connectivity in Ether-Based Polymer Electrolytes},
author = {Pesko, Danielle M. and Webb, Michael A. and Jung, Yukyung and Zheng, Qi and Miller, Thomas F. and Coates, Geoffrey W. and Balsara, Nitash P.},
abstractNote = {In this paper, we perform a joint experimental and computational study of ion transport properties in a systematic set of linear polyethers synthesized via acyclic diene metathesis (ADMET) polymerization. We measure ionic conductivity, σ, and glass transition temperature, Tg, in mixtures of polymer and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt. While Tg is known to be an important factor in the ionic conductivity of polymer electrolytes, recent work indicates that the number and proximity of lithium ion solvation sites in the polymer also play an important role, but this effect has yet to be systematically investigated. Here, adding aliphatic linkers to a poly(ethylene oxide) (PEO) backbone lowers Tg and dilutes the polar groups; both factors influence ionic conductivity. To isolate these effects, we introduce a two-step normalization scheme. In the first step, Vogel–Tammann–Fulcher (VTF) fits are used to calculate a temperature-dependent reduced conductivity, σr(T), which is defined as the conductivity of the electrolyte at a fixed value of T – Tg. In the second step, we compute a nondimensional parameter fexp, defined as the ratio of the reduced molar conductivity of the electrolyte of interest to that of a reference polymer (PEO) at a fixed salt concentration. We find that fexp depends only on oxygen mole fraction, x0, and is to a good approximation independent of temperature and salt concentration. Molecular dynamics simulations are performed on neat polymers to quantify the occurrences of motifs that are similar to those obtained in the vicinity of isolated lithium ions. Finally, we show that fexp is a linear function of the simulation-derived metric of connectivity between solvation sites. From the relationship between σr and fexp we derive a universal equation that can be used to predict the conductivity of ether-based polymer electrolytes at any salt concentration and temperature.},
doi = {10.1021/acs.macromol.6b00851},
journal = {Macromolecules},
issn = {0024-9297},
number = 14,
volume = 49,
place = {United States},
year = {2016},
month = {7}
}

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Cited by: 18 works
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