Understanding Ionic Liquids on Different Length and Time Scales

Ionic liquids (ILs) are a novel class of materials that has attracted significant attention from both fundamental science and engineering. The main feature of ILs is their low melting point despite being salts, in fact, their liquid region often extends to well below room temperature. At the same time, the Coulombic interactions present in any salt are still rather strong in the liquid state, which gives rise to several unique properties, that is a low volatility and flammability, thermal and electrochemical stability, a large concentration of mobile charge carriers as well as a special adhesive and viscous behavior. Moreover, the possibility to combine a huge variety of different (possibly functionalized) cations and anions allows one to tailor or fine-tune their properties. For these reasons, ILs have been widely employed for various technological applications, for instance as electrolytes in batteries or supercapacitors, as catalysts, lubricants, or as solvents for specific chemical syntheses.

Despite all these advances, several issues remain. Concerning the experimental characterization, it is difficult to resolve the local structure of the ions or the involved dynamical processes down to the molecular level, whereas for the theoretical modeling, it is challenging to take the long-ranged electrostatic interactions, the asymmetry between the ions and the internal degrees of freedom of the molecules properly into account. For the latter, simulations can significantly contribute to a better understanding, however, due to the considerable computational demand, numerical methods are limited to rather small systems. While each approach thus addresses the physics of ILs on specific length and time scales, only a comprehensive understanding of the interplay between the detailed chemistry of the IL on one hand and the resulting macroscopic properties on the other hand will allow a direct improvement of IL-based materials for state-of-the-art applications. This workshop therefore aims to bridge the scales between experiment, theory, and simulation, and to promote a vivid exchange of ideas between scientists from all three approaches.