Formation dynamics of graphite intercalation compounds: An {\em ab initio} study

In response to the rising interest in functionalized graphitic nanostructures for energy applications, we study the intercalation of potassium in graphene bi-layers. Our {\em ab initio} molecular dynamics calculations, based on the density functional force field and simulating conditions at 900~K, provide microscopic insight into the dynamics of the intercalation process. Our model system consists of wide graphitic ribbons with hydrogenated edges and a varying number of K atoms in the unit cell. We find that following initial charge transfer from K to graphite upon adsorption, K$^+$ ions diffuse efficiently along the surface. After reaching the edge, K$^+$ ions experience further stabilization upon entering the region in-between graphene layers, accompanied by a substantial increase of the graphene inter-layer distance. We observe both intercalation and de-intercalation as competing processes in our canonical ensemble under steady-state conditions.