Effect of graphite surface structure on initial irreversible reaction in graphite anodes

The initial irreversible reaction that occurs in graphite anodes during the first lithium intercalation in lithium rechargeable batteries was studied in view of graphite surface structure. Graphitized mesophase spheres and pitch-based carbon fibers, which show low irreversible capacity, were shown to have turbostratic surface regions and highly graphitized cores using Ar-ion laser Raman spectroscopy. Burning off these surface regions resulted in remarkable increases of initial irreversible capacity. Those results can be explained by a proposed model that a turbostratic structure of the graphite surface region resists drastic swelling of interlayer spaces arising from cointercalation of solvated ions and depresses the side reaction. (C) 1999 The Electrochemical Society. S0013-4651(98)06-049-2. All rights reserved.