Defect-mediated leakage in lithium intercalated bilayer graphene

Lithium intercalation in bilayer graphene has been investigated for battery applications, but it also provides a potentially stable method for n-type doping for electronics applications. Here, we use density functional theory to investigate the stability of lithium-intercalated bilayer graphene with respect to migration through lattice defects. By calculating energy barriers for through-defect migration, we find that only multivacancies with more than two missing atoms pose a significant threat for lithium egress. Furthermore, entry through a divacancy is significantly more energetically favorable than exit, implying that divacancies may be beneficial for thermal creation of intercalated bilayers. The calculations also show that, though energy barriers for through-defect Li diffusion are significantly different in monolayer and bilayer graphene, additional over-layers (such as hexagonal boron nitride) do not significantly alter the exit barrier in an intercalated bilayer.