锂离子电池负极材料纳米多孔硅/石墨/碳复合微球的制备与性能

Preparation and Performance of Nano-porous Si/Graphite/C Composite Microspheres as Anode Material for Li-ion Batteries

以硅藻土为原料,通过镁热还原反应得到多孔硅,进一步利用砂磨得到纳米多孔硅,然后通过球磨将其与片状石墨和沥青均匀混合,采用喷雾干燥技术造粒,高温煅烧后制备了纳米多孔硅/石墨/碳复合微球.对所得复合微球的结构和理化性质进行了表征.纳米多孔硅/石墨/碳复合微球作为锂离子电池负极材料展示出较高的可逆容量、优异的循环稳定性(100次循环后容量仍为790 mA·h/g,容量保持率可达96.7%)及较好的倍率性能.

Porous Si was obtained from magnesiothermal reduction method using diatomite as the precursor, sand milling was carried out to prepare nano-porous Si(np-Si), After that, the np-Si was uniformly mixed with flake graphite and pitch by ball milling. Then np-Si/graphite/C composite microspheres were prepared by spray drying technology and calcined at high temperature. The structure and physicochemical properties of the composite microspheres were characterized. As anode material for Li-ion batteries, the results from electrochemical test reveal that the composite microspheres exhibit high reversible capacity(817 mA·h/g), excellent cycle stability(790 mA·h/g with 96.7% capacity retention after 100 cycles) and good rate performance. The superior electrochemical characteristics are mainly attributed to the hierarchical buffer structures composed of nanosized porous Si, graphite and pitch carbonized outer carbon, which effectively suppress the volume expansion of Si.