Microstructural and Dynamical Heterogeneities in Ionic Liquids
Abstract
Energy is essential to human society to ensure our quality of life and to underpin all other elements of the economy. The world has reached a pivotal age of energy awareness due to accelerated consumption of conventional energy sources (fossil fuels, coal, natural gas, et al.). How to effectively reduce inefficient consumption of these natural sources, and in the meantime actively seek new innovative sustainable energy sources with minimized greenhouse effect are major research topics and have attracted wide spread efforts throughout the world.
Ionic liquids (ILs), a special category of molten salts solely composed of ions, have attracted significant attention in diverse industrial communities due to their multifaceted properties. Either used as electrolytes in electrochemical devices, or as adsorbents for CO2 capture, the functional performance of (poly) ILs is essentially determined by structural and dynamical properties of ionic species in local ionic environments, which are highly heterogeneous and are correlated with delicate interactions among ionic species, potential impurities, and their intrinsic interactions with charged boundaries (electrodes). A thorough understanding of microstructural and dynamical heterogeneities of (poly) ILs in bulk liquids and in confined environments is pivotal for designing and synthesizing appropriate ionic species before advancing their performance in specific applications.
Concerning the current research status of ILs, the traditional trial-and-error way to find appropriate ILs and to optimize their functional performance leads to huge cost on material synthesis and experimental characterizations. Additionally, a judicious selection of ion pairs with desirable physicochemical properties to meet specific requirements remains terra incognita. Thus an economical pre-screening procedure should be established to determine essential structure-property relationship in representative IL systems. 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. This is particularly useful for (poly) ILs because of their large diversities and complicated landscape of intermolecular interactions.
The aim of this research program is to develop an integrated modelling protocol and to build hierarchical ionic models for representative ILs of (poly) vinyl-triazolium and triazolide 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 (poly) ILs, as well as other essential factors (different solid surfaces and potential impurities in ILs) affecting these heterogeneous quantities in bulk liquids and in confined environments. Simulation results obtained at microscopic level and experimental data measured at macroscopic level 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.
