The Li ion battery with high power and long life is required for the hybrid electronic vehicle. A new carbon anode material called “ICOKE” has been prepared by the graphitization of coke at ca. 2000°C and is shown to have excellent pulse charge/discharge characteristics and long cycle performance. The charge/discharge reaction mechanism of ICOKE was investigated in detail based on the result of cyclic voltammetry and X-ray diffraction profile change of ICOKE before and after charging. As a result, it was found that Li-intercalation reaction to ICOKE proceeds without forming higher stage compounds and the 1st and the 2nd stage compounds are directly formed.