锂离子电池高比容量FeSn_2-C复合负极材料的合成与性能

Synthesis and Properties of FeSn_2-C Composites as Anode Materials for Lithium-Ion Batteries

Sn基合金负极材料具有高达990 mAh·g-1的理论比容量,但其也存在因脱嵌锂过程发生巨大的体积变化而导致循环性能较差的问题.本文以Sn、Fe、石墨为原料利用简易的高能球磨法成功制备了具有核壳结构的FeSn2-C复合物,系统研究了球磨时间、FeSn2相含量对材料物相结构及电化学性能的影响,并分析了电极的失效机理.研究表明,球磨时间的增加有利于FeSn2金属间化合物相的形成及材料颗粒的细化,进而有利于材料比容量的增加及循环性能的提升;FeSn2相含量的增加能够提高FeSn2-C材料的比容量,但会降低FeSn2-C电极的循环稳定性.经工艺优化及组分调节,球磨24 h合成的Sn20Fe10C70材料具有最优的电化学性能,材料的比容量在540mAh·g-1左右,并能稳定循环100次,是一种非常有发展前途的锂离子电池高比容量负极材料.

Tin has a theoretical specific capacity as high as 990 mAh·g-1, and is thus a potential anode material for high-energy-density lithium-ion batteries. However, it suffers from a huge volume change during lithiation/delithiation process, leading to poor cycle performance. In this paper, core/shel structured FeSn2-C composites were successful y synthesized by a simple high-energy bal mil ing technique with Sn, Fe, and graphite powder as raw materials. The FeSn2-C composite was evaluated as an anode material for lithium-ion batteries. The influence of mil ing time and final phase composition on the microstructure and electrochemical performance of FeSn2-C composites was systematically investigated. The failure mechanism of the FeSn2-C electrode was also analyzed. The results reveal that long mil ing time can promote the mechanical al oying process of the FeSn2 phase and reduce the particle size of the FeSn2-C composite, which are beneficial for the increase of the specific capacity and the improvement of the cycle performance of the FeSn2-C electrode. A high FeSn2 phase content leads to a high specific capacity of the FeSn2-C composites but poor cycling stability of the electrode. The optimized Sn20Fe10C70 composite prepared by bal mil ing for 24 h （500 r·min-1） shows the best electrochemical performance with a capacity about 540 mAh·g-1 for 100 cycles. The synthesized Sn20Fe10C70 composite is a promising anode material for high-energy-density lithium-ion batteries.