Structural factors on stability of fluoride- or fluorine-graphite intercalation compounds

The stability of acceptor type GIC has been discussed in terms of in-plane structures of intercalated species and chemical bond between guest and host. GIC is strongly stabilized when intercalated fluoride or chloride takes a bridging structure in which fluorine or chlorine atom of MX6 (X:F, Cl) octahedron is shared by cations. Examples are CxTiF5, CxCuCl2, CxNiCl2 etc. The 'nestiling' of MF6 anion into hexagons of carbon sheets also gives high stability to a GIC. An example is GIC of VF6- having a small central atom. A special case is CxF type GIC in which ionic or semi-ionic C-F bonds contribute to the high stability of the compound.