Effect of heat-treatment and additives on the particles and carbon fibers as anodes for lithium-ion batteries

Carbon fiber (CF) and mesocarbon microbead (MCMB) precursors were heat-treated at 700–2800 °C, 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.