  The effect of the curvature of bilayer graphene on the interlayer diffusion
of Li atoms is investigated using molecular dynamics simulations. A spectacular
enhancement of the diffusion constant parallel to the folding axis is found.
The ratio of the parallel to the perpendicular diffusion depends on the
buckling direction and stacking type, and it increases with the degree of
buckling. The strongest anisotropy is observed in the case of fixed zig-zag
edges. A comparison with the interlayer diffusion of Na suggests that the
strong asymmetry in the vibrational states of buckled graphene and also the
smaller mass of Li are likely to contribute to the observed diffusion
enhancement. This work opens a new pathway to develop highly-efficient anodes
for rechargeable alkaline batteries.
