Prediction of ionic conductivity and transport mechanism in polymer electrolytes using molecular dynamics

Polymer solid electrolytes are promising for Li-metal batteries because of easy processing, and better safety than liquid electrolytes. However, Li-ion diffusivity in the most widely used polymer (polyethylene oxide, or PEO) is relatively low. Considering the vast landscape of polymer compounds, there is a need to narrow down and identify new promising polymers with better Lithium ion transport through atomistic simulation methods. In this work, we develop a molecular dynamic simulation (MD) model which enables prediction of Li ion conductivity in various polymer systems at high Li-salt concentration. The model methodology and ionic conductivity experimental validation will be presented for polymers with various high Li-salt concentrations typical in real Li-polymer batteries. We highlight the importance of atom partial charge determination using quantum chemistry in order to ensure accuracy of the model. We also analyze the transport mechanism in the PEO, and explain how modifying polymer geometry & chemistry can activate a different transport mechanism which may enable better Li-ion transport in novel polymer systems.