Synthesis and lithium ion conduction of polysiloxane single-ion conductors containing novel weak-binding borates

Siwei Liang, U. Hyeok Choi, Wenjuan Liu, James Runt, Ralph H. Colby

Research output: Contribution to journalArticle

87 Scopus citations

Abstract

Three borate monomers: lithium triphenylstyryl borate (B1), a variant with three ethylene oxides between the vinyl and the borate (B2) and a third with perfluorinated phenyl rings (B3) were synthesized and used to prepare polysiloxane ionomers based on cyclic carbonates via hydrosilylation. B1 ion content variations show maximum 25 °C conductivity at 8 mol %, reflecting a trade-off between carrier density and glass transition temperature (T g) increase. Ethylene oxide spacers (B2) lower T g, and increase the dielectric constant, both raising conductivity. Perfluorinating the four phenyl rings (B3) lowers the ion association energy, as anticipated by ab initio estimations. This increases conductivity, a direct result of 3 times higher measured carrier density. The ∼9 kJ/mol activation energy of simultaneously conducting ions is less than half that of ionomers with either sulfonate or bis(trifluoromethanesulfonyl) imide anions, suggesting that ionomers with weak-binding borate anions may provide a pathway to useful single-ion Li + conductors, if their T g can be lowered.

Original languageEnglish (US)
Pages (from-to)2316-2323
Number of pages8
JournalChemistry of Materials
Volume24
Issue number12
DOIs
StatePublished - Jun 26 2012

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry

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