A nanostructured honeycomb carbon anode

We have been investigating a general template-based method for preparing nanostructured Li-ion battery electrodes. We have shown that these nanostructured electrodes have improved rate capabilities relative to thin-film control electrodes composed of the same material. Improved rate capabilities are observed because the high-rate capacity obtained from Li+-insertion materials is limited by slow solid-state Li+ transport in the electrode material, and the nanostructured electrodes decrease the distance that Li+ must diffuse in the solid state. We describe here an alternative type of nanostructured electrode material, a honeycomb carbon anode that consists of a thin carbon film containing an ordered array of monodispersed nanoscopic pores. This honeycomb carbon anode shows a low-rate discharge capacity of 325 mA hg(-1), close to that of graphite. At high discharge rates (10 C), the honeycomb anode, delivers 50 times the capacity of a thin-film control anode that did not contain the honeycomb of nanopores. Improved rate capabilities are obtained because penetration of solvent and Li+ electrolyte into the pore structure of the honeycomb anode insures that the distance Li+ must diffuse in the solid state is smaller than in the thin-film control electrode. (C) 2003 The Electrochemical Society.