Low-crystallized carbon materials for lithium-ion secondary batteries

The charge/discharge characteristics and mechanisms of low-crystallized carbons which have leger capacity than graphite have been investigated, Lour-crystallized carbons have two principal types of charge curve versus Li metal. Hard carbons prepared at 1100 degrees C (H11) show charge curves with a low average potential, whereas soft carbons pyrolyzed at 700 degrees C (S7) show those with a high average potential, These results might depend on the lithium diffusion rate in their non-crystallized sites. The 18650-type Li-ion batteries using H11 have comparable capacity versus graphite, whereas the batteries using S7 have low capacity because of their low chage/discharge efficiency, (C) 1997 Published by Elsevier Science S.A.