Study of Sn[sub 30](Co[sub 1−x]Fe[sub x])[sub 30]C[sub 40] Alloy Negative Electrode Materials Prepared by Mechanical Attriting

A vertical axis attritor was used to prepare several compositions of for . The attrited materials were studied using X-ray diffraction (XRD), Mössbauer effect spectroscopy ( and ), and electrochemical methods. XRD and Mössbauer studies showed evidence of a nanostructured phase, most prominent near , and nanocrystalline , most prominent near . The nanostructured phase is thought to be nanoscopic grains of amorphous in a carbon matrix. Mössbauer effect spectroscopy showed an increase in the amount of nanoscopic as the Fe content increased, consistent with the formation of in the same material due to the removal of Fe from when is near 1. Electrochemical testing was performed for the , 0.5, and 1 samples. Both the and samples showed excellent capacity retention with a specific capacity of for at least . The irreversible capacity of these samples was about . The sample showed the highest reversible capacity of about but its capacity retention was poor. may be a good compromise, allowing cost reduction by eliminating 50% of the Co while maintaining capacity retention.