Title:	Microstructural and Dynamical Heterogeneities in Ionic Liquids
DNr:	SNIC 2018/7-54
Project Type:	SNIC Small Compute
Principal Investigator:	Yonglei Wang <wangyonl@gmail.com>
Affiliation:	Stockholms universitet
Duration:	2018-11-01 – 2019-11-01
Classification:	10407
Homepage:	https://www.su.se/english/profiles/yonwa-1.187344
Keywords:

Abstract

Room temperature ionic liquids (RTILs) are a special category of molten salts entirely composed of ions with their melting points below or close to room temperature. RTILs have been widely used as lubricant additives in tribology, as absorbents for CO2 capture, and as solvents and electrolytes in electrochemical devices due to their multifaceted properties. These properties can be tuned in a controllable fashion by selecting appropriate cation-anion pairs. The functional performance of RTILs in these applications is essentially determined by microstructural and dynamical properties of ionic species in local ionic environments, which are highly heterogeneous and are intrinsically originated from distinct competition between strong electrostatic interactions between polar groups and favorable dispersion interactions between solvophobic units, as well as other delicate intermolecular associations, such as hydrogen bonding and preferential π type stacking coordinations between heteroaromatic ring planes in constituent ions. In addition, the delicate interactions between ionic species and solid surfaces, and potential impurities also contribute to distinctive heterogeneities for RTILs in confined environments. As such, a thorough understanding of microstructural and dynamical heterogeneities in RTILs is pivotal for designing and synthesizing appropriate ionic species before advancing their performance in specific applications. Molecular simulations, in close interplay with experiments, are well positioned to provide fundamental understanding of complicated phenomena on molecular level due to recent boosts of computer power and advent of smart computational algorithms. Multiscale modeling methodology, unifying first-principle calculations, atomistic, and coarse-grained simulations in a self-consistent computational scheme, is an effective approach to perform simulations over large length and long time scales. This is particularly useful for RTILs because of their large diversities and complicated landscape of intermolecular interactions. In this research project, we seek to develop an integrated multiscale modelling protocol to explore microstructural and dynamical heterogeneities in representative imidazolium and orthoborate IL families. Multiscale modelling simulations will be performed to explore peculiar intermolecular interplay between ionic species and their effect on distinctive microstructural and dynamical heterogeneities in RTILs, as well as other essential factors (different solid surfaces and potential impurities in RTILs) affecting these heterogeneous quantities in bulk liquids and in confined environments. The integration of multiscale modelling simulation results obtained at microscopic level and the available experimental data measured at macroscopic level is expected to unravel fundamental mechanisms governing structural and dynamical heterogeneities in varied physicochemical environments. This will provide critical feedback on how to select/design appropriate ionic moieties before advancing their functional performance in terms of minimum environmental effects and maximum utility in specific applications.