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Transport properties of ionic liquid electrolytes with organic diluents

journal contribution
posted on 01.01.2009, 00:00 authored by Paul Bayley, G Lane, N Rocher, B Clare, A Best, D MacFarlane, Maria ForsythMaria Forsyth
Ionic liquids (ILs) form a novel class of electrolytes with unique properties that make them attractive candidates for electrochemical devices. In the present study a range of electrolytes were prepared based on the IL N-methyl-N-propylpyrrolidinium bis(trifluoromethylsulfonyl) amide ([C3mpyr][NTf2]) and LiNTf2 salt. The traditional organic solvent diluents vinylene carbonate (VC), ethylene carbonate (EC), tetrahydrofuran (THF) and toluene were used as additives at two concentrations, 10 and 20 mol%, leading to a ratio of about 0.6 and 1.3 diluent molecules to lithium ions, respectively. Most promisingly, the lithium ions see the greatest effect in the presence of all the diluents, except toluene, producing a lithium self-diffusion coefficient of almost a factor of 2.5 times greater for THF at 20 mol%. Raman spectroscopy subtly indicates that THF may be effectively breaking up a small portion of the lithium ion–anion interaction. While comparing the measured molar conductivity to that calculated from the self-diffusion coefficients of the constituents indicates that the diluents cause an increase in the overall ion clustering. This study importantly highlights that selective ion transport enhancement is achievable in these materials.

History

Journal

Physical chemistry chemical physics

Volume

11

Issue

33

Pagination

7202 - 7208

Publisher

Royal Society of Chemistry

Location

Cambridge, England

ISSN

1463-9076

eISSN

1463-9084

Language

eng

Publication classification

C1.1 Refereed article in a scholarly journal

Copyright notice

2009, Owner Societies