Characterization of the Solid Electrolyte Interphase at the Li Metal–Ionic Liquid Interface

Abstract The solid electrolyte interphase (SEI) forms on electrode surfaces from decomposition of the electrolyte. However, there is almost no atomistic detail of SEI formation on Li metal anode, a major obstacle in understanding the highly complex battery electrochemistry sufficiently to design high performance batteries. Herein, a realistic atomistic model (39 000 atoms) for the SEI formation at the interface between the Li metal anode and ionic liquid electrolyte using reactive molecular dynamics simulations is provided. A ≈10 nm thick SEI composed of a dense ordered inorganic layer near the Li‐metal anode and a porous organic layer near the electrolyte is found. These results provide new insights into a deeper understanding of the complex SEI that should be useful in developing a new generation of highly efficient batteries.