Abstract: We have prepared a series of Co-Sn alloys by mechanical alloying technology as the negative electrode materials for lithium-ion batteries. The effects of addition of carbon and further heat treatment on the phase composition and the electrochemical performance of the alloys were investigated. X-ray diffraction characterization shows that Co-Sn[n(Co)∶n(Sn)=3∶1] alloys after mechanical alloying can be indexed to the mixture phases of Co₃Sn₂ and Co despite of the heat treatment process, however, carbon-added Co-Sn[n(Co)∶n(Sn)∶n(C)=3∶1∶1] alloys consisted of the mixture phases of CoSn₂ and Co, and turned to CoSn and Co₃Sn₂ phase after heat treatment at 400 and 600 ℃, respectively. The results of charge/discharge test show that the charge/discharge capacity decreases in the following order: CoSn₂>CoSn>Co₃Sn₂, but the cycling profile was improved.

Key words: Lithium ion batteries, Negative electrode materials, CoSn alloy, Sn-based material