Influence of edge and basal plane sites on the electrochemical behavior offlake-like natural graphite for Li-ion batteries

The irreversible capacity loss (ICL) that is observed with carbons in Li-io n batteries is associated with electrolyte decomposition. In this paper, we present the results of an analysis to illustrate the role that the edge an d basal plane sites play on the ICL and first-cycle coulomb efficiency of f lake-like natural graphite. A model of an ideal graphite particle, which is depicted as an ideal prismatic structure, is used to develop an understand ing of the correlation of the fraction of edge sites and particle size for flake-like and cube structures. In the case of flake-like graphite, thin fl akes have higher surface area and higher ICL than thicker flakes, even thou gh the fraction of edge sites is lower. On the other hand, the cube structu re has a high fraction of edge sites but a low ICL and low surface area. Th e analysis presented here suggests that the particle morphology and the sur face area associated with the edge and basal plane sites play a significant role in the electrochemical performance of graphite in Li-ion batteries. ( C) 2001 Elsevier Science B.V. All rights reserved.