Extraordinarily Efficient Conduction in a Redox-Active Ionic Liquid

✍ Scribed by Dr. Verner K. Thorsmølle; Dr. Guido Rothenberger; Dr. Daniel Topgaard; Jan C. Brauer; Prof. Dai-Bin Kuang; Dr. Shaik M. Zakeeruddin; Prof. Björn Lindman; Prof. Michael Grätzel; Prof. Jacques-E. Moser

• Publisher: John Wiley and Sons
• Year: 2011
• Tongue: English
• Weight: 389 KB
• Volume: 12
• Category: Article
• ISSN: 1439-4235
• DOI: 10.1002/cphc.201000819

✦ Synopsis

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.