Advanced carbon anode materials for lithium ion cells

Three kinds of carbon have been used for commercial cells: graphite, soft c arbon and hard carbon. The difference in the structures of these three kind s of carbon is shown clearly using our new model for soft and hard carbon s tructure. The lithium-doped state of these three kinds of carbon is discuss ed using the new structural model and published Li-7 NMR data. A large reve rsible capacity is demonstrated in the hard carbons derived from some veget able fibers. Two mechanisms-one enhancing the adsorbing force of pseudo-met allic lithium atoms and one reducing the repulsion force between doped lith ium atoms-which together produce a high reversible capacity, are explained. (C) 1999 Elsevier Science S.A. All rights reserved.