Incorporating Solvation Effects in Oxidative Stability Predictions of Battery Electrolytes

Accurately predicting the oxidative stability of battery electrolytes is crucial for improving our understanding of high-voltage behavior and rational design of next-generation systems employing novel chemistries. However, commonly applied strategies based on evaluation of orbital occupancies of isolated molecules within density functional theory techniques neglect many-body solvation and interfacial effects that govern the electro-thermodynamics in real systems. Here, we advance a computational methodology that integrates molecular dynamics sampling of local solvation environments with explicit vertical ionization potential (IP) calculations to account for such effects. Our approach allows for both statistical accounting of IP distributions as well as prediction of the oxidized species (e.g., solvent vs anion decomposition). Application of this method to a matrix of electrolytes based on common lithium salts and solvents yields more detailed conclusions that often disagree with those gained through conventional calculations. We also demonstrate that this methodology can capture variations in IP associated with increased salt concentrations as well as the speciation and stability next to electrified model interfaces. This work offers a comprehensive accounting of the microscopic factors and electronic structure considerations that stabilize molecules and their unique solvation environment in modern electrochemical systems.