Influence of solvating plasticizer on ion conduction of polysiloxane single-ion conductors

U. Hyeok Choi, Siwei Liang, Michael V. O'Reilly, Karen I. Winey, James Runt, Ralph H. Colby

Research output: Contribution to journalArticle

35 Scopus citations

Abstract

Lithium ion conduction is investigated for a polysiloxane-based single-ion conductor containing weak-binding borates and cyclic carbonate side chains, plasticized with poly(ethylene glycol) (PEG). The addition of PEG increases the conductivity by up to 3 orders of magnitude compared to the host ionomer. A physical model of electrode polarization is used to separate ionic conductivity of the ionomers into number density of simultaneously conducting ions and their mobility. A reduction in Tg with increasing PEG content boosts ion mobility owing to an increase in polymer chain flexibility. Further, the PEG ether oxygens lower the activation energy of simultaneously conducting ions (from 14 to 8 kJ/mol), significantly increasing conducting ion content by 100X, suggesting that ion aggregates observed in the host ionomer are solvated by PEG. This directly reflects the disappearance of an ion aggregation peak observed in X-ray scattering, and an initial large increase in static dielectric constant (εs), upon addition of PEG, suggesting that ionic aggregation is significantly reduced by a small amount of PEG. Further dilution with lower dielectric constant PEG gradually reduces εs.

Original languageEnglish (US)
Pages (from-to)3145-3153
Number of pages9
JournalMacromolecules
Volume47
Issue number9
DOIs
StatePublished - May 13 2014

All Science Journal Classification (ASJC) codes

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry

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