Carbon fiber (CF) and mesocarbon microbead (MCMB) precursors were heat-treated at 700-2800 degreesC, and the electrochemical and physical properties of the carbons were investigated. These carbons are quite different from natural graphite, which has a well-ordered layer planes where intercalation occur and two distinct surface sites. i.e. basal and edge plane sites. In the case of the fibers. intercalation occur by a single plane (circular area) or by two planes, the circular area and the cylindrical edge. For MCMBs. because of its sphere-like structure, this type of carbon is able to intercalate lithium ions more uniformly (i.e. 360). The effect of additives (B, Ag and Sn) in the two carbon samples (CF and MCMB) on the electrochemical performance was also investigated.