Co-Sn Alloys as Negative Electrode Materials for Rechargeable Lithium Batteries

We have prepared three kinds of intermetallic compounds, i.e., , , and , by mechanical alloying followed by heat-treatment. The results of ex situ X-ray diffraction analysis and charge/discharge tests indicate that the electrochemical reaction of lithium with crystalline intermetallic results in the formation of Li-rich tin phase , whereas the crystalline and alloys only partly form . All three alloys in the low-crystalline obtained by further mechanical milling show improved capacity. shows the best cycling performance among the three alloys, but delivers small capacity. The cycling ability of was also improved by partly introducing Co and C into the alloy.