High rate capability of carbon nanofilaments with platelet structure as anode materials for lithium ion batteries

Carbon nanofilaments (CNFs) with platelet structure have been prepared by liquid phase carbonization using porous anodic alumina template, and their lithium ion insertion/extraction properties have been examined as a function of heat treatment temperature and filament diameter. The CNFs heat-treated at 1000 degrees C reveal higher capacitance and higher rate capability compared with those heat-treated at higher temperatures. Further, it is found that higher reversible capacity is obtained for the CNFs with reduced diameter. The reversible capacity of highly graphitized CNFs formed at 2800 degrees C is less than 200 mA h g(-1) at a current density of 50 mA g(-1), being far lower than the theoretical capacity (372 mA h g(-1)) of graphite. A probable reason is the presence of loop at the edge of graphene layers. (c) 2006 Elsevier B.V. All rights reserved.