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Ion diffusion in molten salt mixtures
journal contribution
posted on 2000-01-03, 00:00 authored by H Every, A Bishop, Maria ForsythMaria Forsyth, D MacFarlaneThe molten salts, 1-methyl,3-ethylimidazolium trifluoromethanesulfonate (triflate salt, MeEtImTf) and 1-methyl,3-ethylimidazolium bis(trifluoromethanesulfonimide) (imide salt, MeEtImNTf2) are colourless ionic liquids with conductivities of the order of 10−2 S cm−1 at room temperature. DSC measurements revealed subambient melting and glass transition temperatures. Analysis of the anion and cation diffusion coefficients suggested that the cation was the dominant charge carrier and that the motion was largely independent of the anion. Haven ratios (HRs) of 1 and 1.6 were determined for the imide and triflate salts, respectively, at 30°C (303 K). Values greater than one imply some degree of ionic association, suggesting that aggregation is present in the triflate salt. Mixing of the salts to form binary systems resulted in enhanced conductivities which deviated from a simple law of mixtures. Thermal analysis showed no evidence of a melting point with only a glass transition observed. Corresponding diffusion measurements for the binaries appeared to show a weighted average of the diffusion coefficients of the pure components. The increased conductivity can be attributed to an increase in the number of charge carriers as a result of decreased ion association in the binary.
History
Journal
Electrochimica actaVolume
45Issue
8-9Pagination
1279 - 1284Publisher
Elsevier Science Pub. Co.Location
New York, N.Y.Publisher DOI
ISSN
0013-4686eISSN
1873-3859Language
engPublication classification
C1.1 Refereed article in a scholarly journalCopyright notice
2000, Elsevier Science Ltd.Usage metrics
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