Abstract
We have prepared Ag-Fe-Sn composite alloy powders as anode material for lithium-ion batteries using mechanical alloying method. These powers with a size of several micrometers are mainly composed of β-Sn, Ag3Sn, and Fe phases. The experimental results revealed that a rational substitution of Fe for Ag induced a significant improvement of the cycling performance of the ternary alloy electrodes. Some ternary alloy electrodes were found to be capable of keeping a reversible capacity of 270 Ah/kg over 300 cycles, which were better than that of the Fe-free binary alloy electrodes. The structural changes of the Ag26Fe26Sn48 electrode during charge-discharge cycling were examined by X-ray diffraction analyses. The results reveal that the composite alloy consisting of β-Sn and Ag3Sn phases transforms mostly into that of ternary lithiated phase during Li insertion, and recovers to one involving β-Sn, Ag3Sn and residual Ag2LiSn or AgLi2Sn phases after Li extraction. In this type of lithiation/delithiation process, the composite alloy electrode suffers from a moderate volumetric variation, which is beneficial for the improvement of the cycle life.
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