镁热还原气相法白炭黑制备纳米硅及其电化学性能

Preparation and Electrochemical Properties of Nano-Si by Magnesiothermic Reduction Reaction of Fumed Silica

以气相法白炭黑(FS)为Si前驱体,通过镁热还原工艺和对获得的NPs-Si进行SiOx和C复合包覆,制备出NPs-Si@SiOx@C纳米复合结构,将其用作锂电池负极进行电化学性能测试。研究结果表明:镁热还原过程分两步进行,即SiO_2与Mg先生成Mg2Si中间相,Mg2Si继续与SiO_2反应生成Si的反应路径;根据此规律镁热还原气相法白炭黑的Si转化率达87.9%。电化学性能测试中NPs-Si@SiOx@C负极在2.0 A·g-1的电流密度下有1 300 mAh·g-1的容量平台,1 000次循环后的放电比容量为964.2mAh·g-1,容量保持率达75%。

Using fumed silica （FS） as Si precursor, the structure NPs-Si@SiOx@C nanocomposite was prepared by magnesiothermic reduction reaction and coating the obtained NPs-Si with SiOx and C, which was used as the lithium battery negative and tested for electrochemical performance. The results show that the magnesiothermic reduction reaction process was carried out in two steps. Firstly, SiO2 reacted with Mg to form Mg2Si intermediate phase, and then Mg2Si continued to react with SiO2 to form Si. And a high Si yield of magnesiothermic reduction reaction of fumed silica reached 87.9% according to the rule. The NPs-Si@SiOx@C anode had a capacity platform of 1 300 mAh·g-1 at a current density of 2.0 A·g-1 in the electrochemical performance test. And the specific capacity is 964.2 mAh·g-1 after 1 000 cycles with a capacity retention rate of 75%.