Ih new carbonaceous material with large capacity and nigh efficiency for rechargeable Li-ion batteries

Polycyclic aromatic hydrocarbons (PAHs) with a discharge capacity of 1017 m Ah/g and efficiency of 81.5% were developed for rechargeable Li-ion batteri es using isotropic pitch as the raw material. The PAHs have a very small sp ecific surface area and small micropores. X-ray diffraction results show th at PAHs consist of a few graphene sheets stacked in a parallel fashion (L-c = 16 Angstrom) and separated by a small distance (d(002) = 3.46 Angstrom). The results of solid-state C-13-nuclear magnetic resonance suggest that th e graphene sheets have a coronene-like structure, namely, they show a disk- like shape. Based on its structural characteristics, we proposed a mechanis m for Li-ion storage. (C) 2000 The Electrochemical Society. S0013-4651(00)0 1-127-7. All rights reserved.