机械化学法原位合成硅／锡二元储锂母体复合负极材料的研究

Synthesis of Si/Sn Binary Lithium-storage Host Composite Anode Materials by in-situ Mechanochemical Reaction

以高活性、低熔点金属锂为还原剂,在惰性气氛保护下分别将一氧化硅和氧化亚锡还原为单质硅和锡。通过调节球磨参数并加入适量助磨剂有效抑制因金属锂熔化导致的物料结块现象,得到将纳米硅、锡颗粒均匀分散在含锂化合物基体中的二元储锂母体复合材料。通过该方法得到的复合材料中硅、锡颗粒粒径明显小于商品化的纳米硅和纳米锡,不仅能最大限度降低硅、锡颗粒的体积效应,避免纳米粉体的分散工序,且能大大降低材料的制备成本。交流阻抗和充放电循环测试显示,金属锡作为另一种储锂母体既能为复合材料提供部分可逆容量,也能有效降低活性物质颗粒之间的电荷转移电阻,改善材料的循环稳定性。复合材料经过30次循环后仍能释放出高达550mAh·g-1的可逆容量,容量保持率为84%。

A binary lithium-storage composite anode material containing nano-sized silicon and tin particles was synthesized by an in-situ mechanochemical reaction using silicon monoxide, tin monoxide as oxidants and lithium metal as reductant. Compared with other silicon-containing or tin-containing composites using commercial silicon and tin powders as active particles, the as-obtained composite could deliver a reversible capacity of 550 mAh·g-1 for up to 30 cycles with capacity retention above 84%. The superior electrochemical properties were attributed to small absolute volume changes of nano-sized lithium-storage particles, narrow distribution of nano-sized particles and improvement of electric contact between active particles after addition of tin particles.