Multi-scale Simulations of Ion Transport in Polymeric Electrolytes

Optimizing ion transport properties in polymeric electrolytes is paramount to develop solid-state lithium-ion batteries for future electrical vehicles. To mitigate the material design process from a molecular structure and architecture perspective, we use a combination of theoretical analysis and multi-scale simulations incorporating atomistic and coarse-grained models to study the fundamentals of ion transport phenomena in polymeric systems. The configurations of PEO chains are analyzed in both melt state and concentrated LiTFSI/PEO solutions. The oxygen-oxygen correlations along the polymer backbone can be described by a single or double exponential function. We further develop a coarse-grained model based on the mapping of PEO macromolecules into ideal chains with an effective Kuhn length, in which ion hopping is captured by a dynamic bond formation/breaking scheme. This approach allows for bridging multiple time and length scales to investigate ion diffusion in polymeric systems with hierarchical molecular structures such as combs and bottlebrushes.