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Molecular dynamics study of a dual-cation ionomer electrolyte

journal contribution
posted on 18.01.2017, 00:00 authored by Xingyu Chen, Fangfang ChenFangfang Chen, E Jónsson, Maria ForsythMaria Forsyth
The poly(N1222)xLi1-x[AMPS] ionomer system with dual cations has previously shown decoupled Li ion dynamics from polymer segmental motions, characterized by the glass transition temperature, which can result in a conductive electrolyte material whilst retaining an appropriate modulus (ie. stiffness) so that it can suppress dendrite formation, thereby improving safety when used in lithium metal batteries. To understand this ion dynamics behavior, molecular dynamics techniques have been used in this work to simulate structure and dynamics in these materials. These simulations confirm that the Li ion transport is decoupled from the polymer particularly at intermediate N1222+ concentrations. At 50 mol% N1222+ concentration the polymer backbone is more rigid than for higher N1222+ concentrations, but with increasing temperature Li ion transport is more significant than polymer or quaternary ammonium cation motions. Here we suggest an ion hopping mechanism for Li+, arising from structural rearrangement of ionic clusters that could explain its decoupled behavior. Higher temperatures favor an aggregated ionic structure as well as enhancing these hopping motions. The simulations discussed here provide an atomic-level understanding of ion dynamics that could contribute to designing an improved ionomer with fast ion transport and mechanical robustness.

History

Journal

Chemphyschem

Volume

18

Issue

2

Pagination

230 - 237

Publisher

Wiley-VCH

Location

Weinheim, Germany

eISSN

1439-7641

Language

eng

Publication classification

C Journal article; C1 Refereed article in a scholarly journal

Copyright notice

2016, Wiley-VCH