High temperature annealing effects on carbon spheres and their applications as anode materials in Li-ion secondary battery

Carbon spheres (CSs) have been subjected to a high temperature annealing process at 2800 degrees C under an Ar atmosphere. These high temperature annealed carbon spheres (HTACSs) have been characterised by SEM, HRTEM, BET surface area, XRD, Raman, SQUID and TGA techniques. The study indicates that the original spheroidal morphology of CSs have been converted to polyhedral. The graphitic flakes possessing relatively short range order of which the original are composed of appear to have coalesced into more extended graphitic layers possessing long range order. Furthermore three dimensional interplanar graphitic ordering occurs. Charge-discharge capacity measurements have been performed on both carbon materials to access the potential of these materials in Li-ion secondary battery applications. The measurements indicate that HTACSs exhibit better performance than CSs in terms of greater reversible capacity and their longer plateau in voltage profiles. (c) 2005 Elsevier Ltd. All rights reserved.