新型蜂窝结构Si/Co3O4复合材料的研究

本文通过超声分散、水热生长和煅烧方法制备了新型蜂窝结构Si/Co3O4复合负极材料，在此基础上研究其复合结构与电化学性能的关系。采用X射线衍（XRD）、扫描电子显微镜（SEM）和透射电子显微镜（TEM）对复合材料的物相、微观形貌进行表征，并采用电化学手段对其性能进行测试。结果表明:硅纳米颗粒主要分布于Co3O4蜂窝孔洞结构的内层；相比于纯Si负极材料，蜂窝结构Si/Co3O4复合材料具有更好的结构稳定性、倍率性能和循环性能，首次放电比容量为1475 mAh g-1，第二次维持在851 mAh g-1，经过75 次循环后放电比容量仍有 802 mAh g-1，较第二次比容量损失率仅为0.17%/周，这主要是归因于硅纳米颗粒和Co3O4之间存的空隙为Si负极嵌锂过程中的体积膨胀提供了空间，有效缓冲Si负极的体积变化。

Preparation and Electrochemical Performance of New Cellular Structure Si/Co3O4Composite Material

A novel honeycomb-like Si/Co3O4 anode composite was prepared through sonication dispersing, hydrothermal growth and calcinaton successively. The composition and morphology were characterized by XRD, SEM and TEM. Its electrochemical performances were tested with half cells using CV, GC, RC and EIS characterizations. Results showed that Si particles are well embedded in the porous structure, and the composite anodes manifest much better stability, cycle performance and rate performance than the pristine silicon. The composite anode delivered an initial discharge capacity of 1475 mAh g-1, with 851 mAh/g maintained at 2nd cycle. After 75cycles, the discharge capacity was maintained at 802 mAh g-1, suggesting a loss of 0.77%/cycle Vs. 2nd discharge capacity. The improvement are mainly attributed to that the pores well alleviate the volume expansion of Si particles inside and this slows down the anode degradation.