Negative transference numbers in poly(ethylene oxide)-based electrolytes
By Danielle M. Pesko, Ksenia Timachova, Rajashree Bhattacharya, Mackensie C. Smith, I. Villaluenga, J. Newman, N. Balsara. 2017
209 citations recorded by the source corpus.
Author(s): Pesko, DM; Timachova, K; Bhattacharya, R; Smith, MC; Villaluenga, I; Newman, J; Balsara, NP | Abstract: © The Author(s) 2017. Published by ECS. All rights reserved. The performance of battery electrolytes depends on three independent transport properties: ionic conductivity, diffusion coefficient, and transference number. While rigorous experimental techniques for measuring conductivity and diffusion coefficients are well-established, popular techniques for measuring the transference number rely on the assumption of ideal solutions. We employ three independent techniques for measuring transference number, t+, in mixtures of polyethylene oxide (PEO) and lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) salt. Transference numbers obtained using the steady-state current method pioneered by Bruce and Vincent, t+,SS, and those obtained by pulsed-field gradient NMR, t+,NMR, are compared against a new approach detailed by Newman and coworkers, t+,Ne, for a range of salt concentrations. The latter approach is rigorous and based on concentrated solution theory, while the other two approaches only yield the true transference number in ideal solutions. Not surprisingly, we find that t+,SS and t+,NMR are positive throughout the entire salt concentration range, and decrease monotonically with increasing salt concentration. In contrast, t+,Ne has a non-monotonic dependence on salt concentration and is negative in the highly-concentrated regime. Our work implies that ion transport in PEO/LiTFSI electrolytes at high salt concentrations is dominated by the transport of ionic clusters.
Subfields: Automotive Engineering, Electrical and Electronic Engineering
View Paper: https://www.semanticscholar.org/paper/62a37f4861ef924210259bc04bc440831df8daaa
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In Electrical and Electronic Engineering
Citations in the corpus
- Diffusion and migration in polymer electrolytes (2020, methodology): “26 Stefan-Maxwell diffusion coefficients, Dij, can be obtained by measuring the conductivity by ac impedance, the mutual salt diffusion coefficient by the restricted diffusion method, the steady current measured in a dc experiment, and data from concentration cells.[19, 61, 62] These”