Exfoliation process of graphite via intercalation compounds with sulfuric acid

Exfoliation process of graphite via its residue compound from intercalation compound with sulfuric acid was discussed by measuring exfoliation volume and pore sizes among and inside their worm-like particles. Exfoliation process was found to divide into three steps, below 650, 650-800 degreesC and above 800 degreesC. Below 650 degreesC, exfoliation of graphite flakes to form worm-like particles occurred rapidly and so exfoliation volume increased. Above 650 degreesC, increase in exfoliation volume, i.e. decrease in bulk density, became more rapid, but the growth of pores inside the particles was not so much pronounced. Above 800 degreesC, the increasing rate in exfoliation volume seemed to become slow, change in bulk density looking small, but pores inside the particles grew more. Exfoliated graphite prepared at 1000 degreesC had the exfoliation volume of about 0.15 m(3)/kg (bulk density of about 7 kg/m(3)), which is composed of large spaces with the cross-sectional area of more than 8000 mum(2) and worm-like particles containing ellipsoidal pores with averaged cross-sectional area of about 320 mum(2) and sizes of about 31 x 11 mum(2). (C) 2003 Elsevier Ltd. All rights reserved.