Simulation of Spreading and Interfacial Behavior of Deep Eutectic Electrolytes on Two Facets of Li Metal Electrodes: Improving Li Metal Batteries’ Performance

Rechargeable lithium metal batteries (LMBs) with a remarkably high specific capacity and low anode potential can be a promising energy resource. However, their commercialization has faced challenges because of the poor interfacial compatibility, dendrite formation, and safety risks associated with conventional liquid electrolytes. To address these challenges, significant attention has been paid to developing electrolytes for LMBs. Motivated by a recent study on a nonflammable deep eutectic electrolyte (DEE) composed of lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) and dimethylmalononitrile (DMMN) [https://doi.org/10.1002/anie.202411224], which exhibits outstanding interfacial compatibility, we investigate the performance of this electrolyte in LMBs. Therefore, we employ molecular dynamics simulations and density functional theory calculations to elucidate the structural interactions of the LiTFSI:4DMMN DEE and its spreading behavior on lithium metal with two different facets involving Li(100) and Li(110). Our results reveal that DMMN enhances Li+ coordination and facilitates LiTFSI dissociation. The DEE demonstrates superior wetting and spreading with faster dynamics over the Li(110) surface compared to Li(100), indicating that the Li(110) facet is more favorable to be used as an electrode in LMBs. This study unravels the molecular interactions at the electrode/electrolyte interface, highlighting the LiTFSI:4DMMN DEE as a superior electrolyte for high-performance LMBs and illustrating how the crystallographic structure of the electrode influences the interaction and spreading of the electrolyte on the electrode. We hope this study paves the way for future advancements in the development of high-performance and safe LMBs, contributing to the ongoing innovation in energy storage technologies.