Simple preparation of Cu6Sn5/Sn composites as anode materials for lithium-ion batteries

摘要

Cu _(6) Sn _(5) /Sn composites are directly fabricated by a high energy mechanical milling technique and subsequent heat treatment. In particular, the effects of the ratios of Sn to Cu _(6) Sn _(5) (Cu _( x ) Sn _( y ) , x = 10 ? y , y = 4.5, 7 and 9) on the lithium-ion batteries performances are investigated. The results show that the sample with y = 4.5 is a single-phase Cu _(6) Sn _(5) , the sample with y = 7 is slightly Sn rich in the Cu _(6) Sn _(5) (Sn < Cu _(6) Sn _(5) ), and the sample with y = 9 is excessively Sn rich in the Cu _(6) Sn _(5) (Sn > Cu _(6) Sn _(5) ). Furthermore, the Cu _(6) Sn _(5) /Sn composite has an obvious structure of a core–shell, only when y = 7. As an anode material for lithium-ion batteries, the Cu _(6) Sn _(5) /Sn composite with y = 7 exhibits a discharge capacity of 761.6 mA h g ~(?1) after the first cycle, 457.8 mA h g ~(?1) after 20th cycles, and an initial coulombic efficiency of 91.37%, which shows a better electrochemical performance than that of y = 4.5 or 9. In addition, after adding 15 wt% of graphite, the sample with y = 7 maintains a discharge capacity of 605.8 mA h g ~(?1) after 100 repeated cycles, higher than many reported Cu–Sn-based anode materials.