The Development of Hierarchical Ion Models and Multiscale Modeling of Tetraalkylphosphonium and Imidazolium Ionic Liquids

Ionic liquid (IL) materials are promising electrolytes with striking physicochemical properties for energy and environmental applications. Heterogeneous structures and transport quantities of ILs are intrinsically intercorrelated and span multiple spatiotemporal scales. Multiscale modeling methodology unifying theoretical calculations, atomistic, and coarse-grained simulations based on successive coarse-graining schemes is an efficient approach to explore complex phase behaviors of these ion-containing materials at extended spatiotemporal scales with a modest computational cost. In this chapter, we will provide several examples concentrated on tetraalkylphosphonium and imidazolium ILs showing how to sketch an effective modeling protocol to obtain force field parameters derived at high-resolution scales being transferred to low-resolution levels in a self-consistent computational scheme using a bottom-up approach bridging different length and time scales. Concluding remarks and an outlook on multiscale strategies in understanding and predictive capabilities of ILs and their mixtures are addressed in the final section to highlight future challenges and opportunities associated with IL materials in multiscale modeling community.