Machine Learning and Reactive Force Field Molecular Dynamics Investigation of Electrolytes for Ultra-fast Charging Li-ion Batteries

The ultra-fast charging batteries have become a bigger demand for electric vehicles. To achieve the fast charging system, the electrolyte system should be optimized with a high balance between ionic conductivity and chemical stability. In recent research, many compounds, including organic ester, formate, and nitrile, were introduced into carbonate-based electrolytes as a co-solvent. However, the understanding of how co-solvents and effect of functional groups improve the electrolyte properties is not yet disclosed. Here we investigate the role of co-solvent that affects electrolyte properties, especially the self-diffusion coefficient by using theoretical reactive molecular dynamics (RMDs) simulations coupled with the advancement in numerical method to compute the correlation between co-solvent properties and the self-diffusion coefficient. We found that the low electron affinity co-solvent and low-density molecule are the keys to improve the Li-ion diffusion in the carbonate-based electrolyte system. Hence, this work could lead the way for developing the new co-solvent for the ultra-fast charging demand.