Studies on heat-treated MPCF anodes in Li ion batteries

The intercalation/deintercalation of lithium ions into the heat-treated mesophase pitch-based carbon fibers (MPCF) was carried out in 1 M LiPF6-ethylene carbonate (EC)/diethyl carbonate (DEC) (1:1, volume ratio) solution at room temperature. LiC6 became incorporated into the heat-treated MPCF via an Li+ intercalation process. The transition stage was observed by a charge-discharge curve, impedance spectrum, and X-ray diffraction (XRD) spectrum. From the observed results, we conclude that the initial intercalation of lithium ions proceeds not by a reversible pathway, but rather, an irreversible path. From the deintercalation to the continuous cycles the lithium ion is intercalated and deintercalated via a reversible pathway. (C) 2002 Elsevier Science B.V. All rights reserved.