The role of electrostatic effects in determining the structure of LiF-graphene interfaces

Lithium fluoride (LiF) is a main component of the solid electrolyte interphase (SEI) in Li-ion batteries. Using density functional theory (DFT) calculations and development of a simple electrostatic model we study the structure and mechanism of LiF growth on graphene. We find that, independent of being in contact or not with the graphene surface, crystalline-LiF nanoclusters (NCs) with (100) facets grow in a three-dimensional mode. These findings are in agreement with recent experimental studies on graphene anodes. We also find that the stabilities of LiF NCs can be predicted by a simple electrostatic model for ionic NCs. Since the main components of the SEI layer are ionic compounds, this study shows how electrostatic effects can control the atomic structure of the SEI layer in Li-ion batteries. (fast track communication)