Electrolyte Solvent-Ion Configuration Deciphering Lithium Plating/Stripping Chemistry for High-Performance Lithium Metal Battery

Abstract

Electrolyte engineering plays a critical role in tuning lithium plating/stripping behaviors, thereby enabling safer operation of lithium metal anodes in lithium metal batteries (LMBs). However, understanding how electrolyte microstructures influence the lithium plating/stripping process at the molecular level remains a significant challenge. Herein, using a commonly employed ether-based electrolyte as a model, the role of each electrolyte component is elucidated and a relationship between electrolyte behavior and the lithium plating/stripping process is established by investigating the effects of electrolyte compositions, including solvents, salts, and additives. The variations in Li⁺ deposition kinetics are not only analyzed by characterizing the lithium deposition overpotential and exchange current density but it is also identified that the intermolecular interactions are the previously unexplored cause of these variations by 2D nuclear overhauser effect spectroscopy (NOESY). An interfacial model is developed to explain how solvent interactions, distinct roles of anions, and critical effects of additives influence Li⁺ desolvation kinetics and the thermodynamic stability of desolvation clusters during lithium plating/stripping process. This model clarifies how these configurations of solvents and ions are related to the macroscopic properties of lithium plating/stripping chemistry. These findings contribute to more uniform and controllable lithium deposition, providing valuable insights for designing advanced electrolyte systems for LMBs.