Partial breaking of the Coulombic ordering of ionic liquids confined in carbon nanopores

Ryusuke Futamura, Taku Iiyama, Yuma Takasaki, Yury Gogotsi, Mark J. Biggs, Mathieu Salanne, Julie Ségalini, Patrice Simon, Katsumi Kaneko

Research output: Contribution to journalArticle

90 Citations (Scopus)

Abstract

Ionic liquids are composed of equal quantities of positive and negative ions. In the bulk, electrical neutrality occurs in these liquids due to Coulombic ordering, in which ion shells of alternating charge form around a central ion. Their structure under confinement is far less well understood. This hinders the widespread application of ionic liquids in technological applications. Here we use scattering experiments to resolve the structure of a widely used ionic liquid (EMI-TFSI) when it is confined inside nanoporous carbons. We show that Coulombic ordering reduces when the pores can accommodate only a single layer of ions. Instead, equally charged ion pairs are formed due to the induction of an electric potential of opposite sign in the carbon pore walls. This non-Coulombic ordering is further enhanced in the presence of an applied external electric potential. This finding opens the door for the design of better materials for electrochemical applications.

Original languageEnglish
Pages (from-to)1225-1232
Number of pages8
JournalNature Materials
Volume16
Issue number12
Early online date18 Sep 2017
DOIs
Publication statusPublished - 1 Dec 2017

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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    Futamura, R., Iiyama, T., Takasaki, Y., Gogotsi, Y., Biggs, M. J., Salanne, M., Ségalini, J., Simon, P., & Kaneko, K. (2017). Partial breaking of the Coulombic ordering of ionic liquids confined in carbon nanopores. Nature Materials, 16(12), 1225-1232. https://doi.org/10.1038/nmat4974