Structural studies of the stage III lithium–graphite intercalation compound

Electrochemical intercalation of unsolvated lithium ions into pyrographite has been carried out in LiClO4–carbonate electrolyte solution. The pure stage III lithium–graphite intercalation compound has been isolated and characterized by X-ray diffraction studies. The oriented texture of pyrographite has allowed the separated study of the different families of Bragg reflections. The identity period along the c-axis, Ic, is equal to 1040.80 pm corresponding to an intercalation distance dI equal to 374.80 pm. There is no evidence for a 2D structural organization of the intercalated lithium species. The a and b parameters of the graphite sublattice are equal to 246.84 pm corresponding to an in-plane C–C distance of 142.50±0.05 pm. Comparison between experimental data and some theoretical models suggests a ABA/ACA stacking of the graphene layers along the c-axis with a parameter c equal to 2Ic. However, a contribution of a ABA/ABA stacking with c=Ic is also probable.