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 language | English (US) |
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Pages (from-to) | 2316-2323 |
Number of pages | 8 |
Journal | Chemistry of Materials |
Volume | 24 |
Issue number | 12 |
DOIs | |
State | Published - Jun 26 2012 |
All Science Journal Classification (ASJC) codes
- Chemistry(all)
- Chemical Engineering(all)
- Materials Chemistry