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Enhancing solid-state conductivity through acid or base doping of protic imidazolium and imidazolinium triflate salts

journal contribution
posted on 21.12.2017, 00:00 authored by A L Chong, Haijin Zhu, K M Nairn, Maria ForsythMaria Forsyth, D R Macfarlane
Protic salts, including those showing plastic crystal behavior, are an interesting family of materials being rediscovered for use as solid conducting materials. This work compares two such compounds, 2-methylimidazolium triflate, [2-MeHIm][TfO], and 2-methylimidazolinium triflate, [2-MeHImn][TfO]. This subtle change in structure resulted in substantial differences in thermal behavior; [2-MeHIm][TfO] shows two solid-solid phase transitions while none were observed for [2-MeHImn][TfO]. However, both compounds are in a disordered solid state (ΔSf< 40 JK-1mol-1) resulting in relatively high room temperature conductivities. Neat [2-MeHImn][TfO] had a conductivity above 10-5S cm-1, but the addition of either the component acid or base as dopants resulted in a substantial increase in conductivity, to over 10-4S cm-1at 30 °C. Solid-state1H and19F NMR studies suggest that the dopants enhance the conduction primarily by increasing the proportion of mobile ions in the solid matrix. However, [2-MeHIm][TfO] also displays evidence of proton hopping via the cation.

History

Journal

Journal of physical chemistry C

Volume

121

Issue

50

Pagination

27849 - 27859

Publisher

American Chemical Society

Location

Washington, D.C.

ISSN

1932-7447

eISSN

1932-7455

Language

eng

Publication classification

C1 Refereed article in a scholarly journal

Copyright notice

2017, American Chemical Society