(644f) Modeling the Interface between Lithium Metal and Its Native Oxide

As the economy shifts towards more renewable sources of energy, new technologies are critical to meet the unique demands for energy storage. Among the most promising technologies are batteries. In particular, lithium (Li) metal batteries have received a great deal of attention for next-generation battery chemistries due to their high theoretical capacities. Nonetheless, a key challenge preventing their implementation is an improved understanding of the interfacial layer that forms between the anode and the electrolyte during battery cycling. This layer, also known as the solid electrolyte interphase (SEI) layer, is crucial in overall battery performance. In this study, the structure expected to constitute the innermost layer in the SEI, the native oxide layer on Li metal, is constructed and analyzed using density functional theory (DFT) and ab initio molecular dynamics. Two models were developed for the Li/Li₂O interface: a crystalline slab supercell model and an amorphous oxidized slab model. The interfacial energetics and adhesion, which may be correlated with macroscale properties, are examined. Further, we show that the computed charge state of all atoms and the Li 1s core-level electron binding energies are able to quantitatively distinguish between Li atoms in the metallic region of the interface and those in the oxide region. Lastly, the diffusion of Li⁺ is investigated to determine the effect of the native oxide layer on Li-ion transport. Although the performance of Li metal batteries has been linked to the native oxide layer, this work represents one of the first detailed analyses of this layer.