Interfacial study on solid electrolyte interphase at Li metal anode: Implication for Li dendrite growth

The Solid electrolyte interphase (SEI), either naturally formed or artificially designed, plays a critical role in the stability and durability of Li-ion batteries (LIBs). It is even more important for high energy density electrodes such as Li metal anodes, which is subjected to large volumetric and interfacial variations due to Li deposition/stripping cycles during operation. Currently, there is a lack of understanding of the role of SEI/Li interfaces and their mechanical and electrochemical properties. In this paper, we present an interfacial study to evaluate the two major SEI components, LiF and Li₂CO₃, based on density functional theory (DFT) calculations. The calculated interfacial energy results show that the Li₂CO₃/Li interface has higher interfacial mechanical strength. The density of states (DOS) and electrostatic potential results demonstrate that the LiF/Li interface has higher electron tunneling energy barrier from Li metal to SEI. These results provide quantitative inputs for related meso-scale simulations and valuable insights for advanced electrode protective coating design.