Enabling Predictive Molecular Simulation of Electrolytes for Next Generation Energy Storage Devices

Abstract

High concentration liquid electrolytes, such as water-in-salt electrolytes and ionic liquids, as well as solid state polymer electrolytes are rapidly emerging materials to replace the flammable organic electrolytes widely used in industrial lithium ion batteries. Extensive efforts have been made to understand the mechanisms and to optimize the ion transport properties, which are strongly coupled to the solvent/polymer dynamics in both types of electrolytes. Molecular dynamics (MD) simulation of these systems is challenging due to a number of reasons, including lack of predictive force fields, complex polarization effects occurring both in electrolytes and on electrodes, highly correlated ion motion due to high concentration and strong electrostatic interactions, to name a few. In this talk, I’ll present our ongoing efforts to enable predictive molecular simulations of ionic liquids and polymer electrolytes. Two major advances will be highlighted – the development of predictive multi-scale force field for ILs and polymers based entirely on first-principle calculations, and the development of simulation algorithms to treat surface polarization and proper thermal equilibrium in polarizable MD simulations. New physical insights gained from the new simulation model and simulation algorithms will be discussed, which includes polarization effects on the ion adsorption at air/water and water/electrode interfaces, ion correlation in organic electrolytes, formation of ionic liquid crystals, as well as conformational dynamics in IL-polymer mixtures.