New graphite-antimony composites as anodic materials for lithiumion batteries. Preparation, characterisation and electrochemical performance

Antimony-based graphite composite has been studied as a potential material for negative electrodes for lithium-ion batteries. This material has been synthesised by antimony pentachloride intercalated graphite compound reduction using an original method consisting in the use of activated sodium hydride as reducing agent in tetrahydrofuran. The composites have been characterised by X-ray diffraction and transmission electron microscopy. Graphite deintercalated and antimony nanoparticles embedded in organic matrix have been observed. The electrochemical properties of this new material as lithium-ion anode have been investigated. The obtained results highlight not only the leading role of the particle size of the active material but also the influence of a stabilising organic matrix. In our case, volume changes generally occurring during insertion/extraction of lithium into/from metallic host material, which lead to rapid disintegration and deterioration of Li-alloy electrode seem to be avoided. Indeed the presence of the matrix and the conductivity of graphite work in unison to prevent antimony nanoparticles against agglomeration and lead to a good cycling stability of such composite systems. (C) 2002 Elsevier Science Ltd. All rights reserved.