Graphite–FeSi alloy composites as anode materials for rechargeable lithium batteries

Iron–silicon are prepared by annealing elemental mixtures at 1000 °C followed by mechanical milling. Graphite–Fe20Si80 alloy composites have been prepared by ball-milling a mixture of Fe20Si80 alloy and graphite powder. The microstructure and electrochemical performance of the composites are characterized by X-ray diffraction and an electrochemical method. The FeSi2 matrix is stable for extended cycles and acts as a buffer for the active centre, Si. The Fe20Si80 alloy electrode delivers large initial capacity, but the capacity degrades rapidly with cycling. Fe20Si80 alloy–graphite composite electrodes, however, show good cycleability and a high reversible capacity of about 600 mAh g−1. These composites appear to be promising candidates for negative electrodes in lithium rechargeable batteries.