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The effect of lithium salt doping on the nanostructure of ionic liquids

Aguilera, Luis; Volkner, Johannes; Labrador, Ana LU and Matic, Aleksandar (2015) In Physical Chemistry Chemical Physics 17(40). p.27082-27087
Abstract
In this work we report on the evolution of the structure of two model ionic liquid families, N-alkyl-N-methylpyrrolidinium (Pyr(1n)-TFSI) and 1-alkyl-3-methylimidazolium (C(n)MIm-TFSI) (n = 3, 4, 6 and 8) both containing the bis(trifluoromethanesulfonyl)imide (TFSI) anion, upon the addition of LiTFSI using small angle X-ray scattering (SAXS). The introduction of a lithium salt (Li-salt) tunes the interactions through the substitution of the large cation in the ionic liquid with the small and charge localized lithium ion, thus increasing the coulombic contribution from ion-ion interactions. We find that the introduction of lithium ions results in a restructuring of the polar groups in the ionic liquids. These changes are manifested as an... (More)
In this work we report on the evolution of the structure of two model ionic liquid families, N-alkyl-N-methylpyrrolidinium (Pyr(1n)-TFSI) and 1-alkyl-3-methylimidazolium (C(n)MIm-TFSI) (n = 3, 4, 6 and 8) both containing the bis(trifluoromethanesulfonyl)imide (TFSI) anion, upon the addition of LiTFSI using small angle X-ray scattering (SAXS). The introduction of a lithium salt (Li-salt) tunes the interactions through the substitution of the large cation in the ionic liquid with the small and charge localized lithium ion, thus increasing the coulombic contribution from ion-ion interactions. We find that the introduction of lithium ions results in a restructuring of the polar groups in the ionic liquids. These changes are manifested as an increase in the correlation lengths related to charge alternation of the ions and a more disordered structure. This restructuring is interpreted as a reconfiguration of the anions as they coordinate to the small and ionic lithium. In contrast, the length scale of the mesoscopic heterogeneities related to the clustering of alkyl chains is virtually unchanged with lithium doping. Moreover, the correlation corresponding to alkyl chain domains becomes more well defined with increasing salt concentration, suggesting that Li-salt doping, i.e. an increased columbic interaction in the system, promotes clustering of the alkyl tails. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Physical Chemistry Chemical Physics
volume
17
issue
40
pages
27082 - 27087
publisher
Royal Society of Chemistry
external identifiers
  • wos:000362679300065
  • scopus:84943598869
ISSN
1463-9084
DOI
10.1039/c5cp03825a
language
English
LU publication?
yes
id
24618849-b19c-43ee-89c8-35c4f7714826 (old id 8206225)
date added to LUP
2015-11-26 14:47:42
date last changed
2017-10-22 04:13:48
@article{24618849-b19c-43ee-89c8-35c4f7714826,
  abstract     = {In this work we report on the evolution of the structure of two model ionic liquid families, N-alkyl-N-methylpyrrolidinium (Pyr(1n)-TFSI) and 1-alkyl-3-methylimidazolium (C(n)MIm-TFSI) (n = 3, 4, 6 and 8) both containing the bis(trifluoromethanesulfonyl)imide (TFSI) anion, upon the addition of LiTFSI using small angle X-ray scattering (SAXS). The introduction of a lithium salt (Li-salt) tunes the interactions through the substitution of the large cation in the ionic liquid with the small and charge localized lithium ion, thus increasing the coulombic contribution from ion-ion interactions. We find that the introduction of lithium ions results in a restructuring of the polar groups in the ionic liquids. These changes are manifested as an increase in the correlation lengths related to charge alternation of the ions and a more disordered structure. This restructuring is interpreted as a reconfiguration of the anions as they coordinate to the small and ionic lithium. In contrast, the length scale of the mesoscopic heterogeneities related to the clustering of alkyl chains is virtually unchanged with lithium doping. Moreover, the correlation corresponding to alkyl chain domains becomes more well defined with increasing salt concentration, suggesting that Li-salt doping, i.e. an increased columbic interaction in the system, promotes clustering of the alkyl tails.},
  author       = {Aguilera, Luis and Volkner, Johannes and Labrador, Ana and Matic, Aleksandar},
  issn         = {1463-9084},
  language     = {eng},
  number       = {40},
  pages        = {27082--27087},
  publisher    = {Royal Society of Chemistry},
  series       = {Physical Chemistry Chemical Physics},
  title        = {The effect of lithium salt doping on the nanostructure of ionic liquids},
  url          = {http://dx.doi.org/10.1039/c5cp03825a},
  volume       = {17},
  year         = {2015},
}