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

Pesko, Danielle M. and Webb, Michael A. and Jung, Yukyung and Zheng, Qi and Miller, Thomas F., III and Coates, Geoffrey W. and Balsara, Nitash P. (2016) Universal Relationship between Conductivity and Solvation-Site Connectivity in Ether-Based Polymer Electrolytes. Macromolecules, 49 (14). pp. 5244-5255. ISSN 0024-9297. https://resolver.caltech.edu/CaltechAUTHORS:20160831-130326773

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Abstract

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 salt 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. 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.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/acs.macromol.6b00851DOIArticle
http://pubs.acs.org/doi/abs/10.1021/acs.macromol.6b00851PublisherArticle
http://pubs.acs.org/doi/suppl/10.1021/acs.macromol.6b00851PublisherSupporting Information
ORCID:
AuthorORCID
Pesko, Danielle M.0000-0002-4833-0119
Webb, Michael A.0000-0002-7420-4474
Miller, Thomas F., III0000-0002-1882-5380
Coates, Geoffrey W.0000-0002-3400-2552
Balsara, Nitash P.0000-0002-0106-5565
Additional Information:© 2016 American Chemical Society. Received: April 23, 2016; Revised: July 4, 2016; Published: July 15, 2016. The authors gratefully acknowledge Zhen-Gang Wang for useful discussions. This research was supported by the National Science Foundation under DMREF Award NSF-CHE-1335486. DSC experiments were performed at the Molecular Foundry user facilities at Lawrence Berkeley National Laboratory supported by the Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract DE-AC02-05CH11231. M.A.W. also acknowledges support from the Resnick Sustainability Institute. D.M.P., M.A.W., and Y.J. contributed equally to the work. The authors declare no competing financial interest.
Group:Resnick Sustainability Institute
Funders:
Funding AgencyGrant Number
NSFCHE-1335486
Department of Energy (DOE)DE-AC02-05CH11231
Resnick Sustainability InstituteUNSPECIFIED
Issue or Number:14
Record Number:CaltechAUTHORS:20160831-130326773
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20160831-130326773
Official Citation:Universal Relationship between Conductivity and Solvation-Site Connectivity in Ether-Based Polymer Electrolytes Danielle M. Pesko, Michael A. Webb, Yukyung Jung, Qi Zheng, Thomas F. Miller, III, Geoffrey W. Coates, and Nitash P. Balsara Macromolecules 2016 49 (14), 5244-5255 DOI: 10.1021/acs.macromol.6b00851
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:70075
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:31 Aug 2016 22:11
Last Modified:03 Oct 2019 10:27

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