Lithium manganese oxide-conductive carbon nanocomposite cathodes for rechargeable lithium batteries

A nanostructured lithium manganese oxide (LixMnOz) synthesized by reducing lithium permanganate with methanol in presence of lithium hydroxide has been mixed with conductive carbon in two different ways: ball milling and mixing in a mortar and pestle. The manganese oxide-conductive carbon composite cathodes thus obtained are characterized by electrochemical discharge-charge, density, and Brunauer-Emmett-Teller (BET) surface area measurements as well as by Xray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The ball-milled composites exhibit superior performance in terms of discharge capacity (>200 mAh/g), cyclability, and charge efficiency in lithium cells compared to the composites obtained by mixing in a mortar and pestle. The composites obtained by ball milling are found to have higher density and smaller surface area with an intimate mixing of the manganese oxide and carbon on a nanometer scale to give a nanocomposite. (C) 2002 Elsevier Science B.V. All rights reserved.