title: Extraordinarily efficient conduction in a redox-active ionic liquid.
abstract: Iodine added to iodide-based ionic liquids leads to extraordinarily efficient charge transport, vastly exceeding that expected for such viscous systems. Using terahertz time-domain spectroscopy, in conjunction with dc conductivity, diffusivity and viscosity measurements we unravel the conductivity pathways in 1-methyl-3-propylimidazolium iodide melts. This study presents evidence of the Grotthuss mechanism as a significant contributor to the conductivity, and provides new insights into ion pairing processes as well as the formation of polyiodides. The terahertz and transport results are reunited in a model providing a quantitative description of the conduction by physical diffusion and the Grotthuss bond-exchange process. These novel results are important for the fundamental understanding of conduction in molten salts and for applications where ionic liquids are used as charge-transporting media such as in batteries and dye-sensitized solar cells.
authors.affiliation: Laboratory for Photonics and Interfaces, Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne, Station 6, CH-1015 Lausanne, Switzerland. verner.thorsmolle@epfl.ch
authors.forename: Verner K
authors.initials: VK
authors.lastname: Thorsmølle
authors.forename: Guido
authors.initials: G
authors.lastname: Rothenberger
authors.forename: Daniel
authors.initials: D
authors.lastname: Topgaard
authors.forename: Jan C
authors.initials: JC
authors.lastname: Brauer
authors.forename: Dai-Bin
authors.initials: DB
authors.lastname: Kuang
authors.forename: Shaik M
authors.initials: SM
authors.lastname: Zakeeruddin
authors.forename: Björn
authors.initials: B
authors.lastname: Lindman
authors.forename: Michael
authors.initials: M
authors.lastname: Grätzel
authors.forename: Jacques-E
authors.initials: JE
authors.lastname: Moser
mesh_terms: D004553:Electric Conductivity; D052578:Ionic Liquids / Q000737:chemistry*; D010084:Oxidation-Reduction
chemical_list: D052578:Ionic Liquids