Graphite structure and lithium intercalation

The various commercial graphite structures and their lithium intercalation properties were investigated using X-ray diffraction (XRD) and electrochemical voltage spectroscopy (EVS) techniques. It has been found that most commercially available graphites are a mixture of hexagonal (2H) and rhombohedral (3R) phases. For some graphites, the 3R phase content may exceed 30%. The correlation between graphite lithium intercalation capacity, 2H, 3R phase contents and structural disorder in each phase is discussed. A model is proposed to facilitate the understanding of the relationship between the graphite structures and the lithium intercalation properties. It was found that the total reversible lithium capacity is related to both the 2H and the 3R phase contents, and that the lithium intercalation mechanism in the 2H and 3R structures are similar.