Silicon was regarded as one of the promising anode materials for next generation lithium ion batteries(LIBs) due to its ultrahigh theoretical capacity, abundant resource and environmental friendliness. However, the downsizing of Si to nanoscale dimension was impeded by complicated and expensive methods. Here, the Si nanoparticles are engineered from a magnesiothermic reaction, in which magnesium powder and fumed silica are served as reductant and silicon source, respectively. Sodium chloride is utilized as a heat-scavenger to consume the heat, which generates by the magnesiothermic reduction process. The nano-silicon with an average grain size about 25 nm is successfully obtained, and the yield is as high as 82%. Owing to the small size of the nano-silicon, it exhibits excellent electrochemical performance. The first cycle delithiation capacity is above 1875 mAh·g-1and the first coulombic efficiency is up to 85%. Furthermore, the delithiation capacity maintains 1007 mAh·g-1at a current density of 0.6 A·g-1after 50 cycles.%硅因其理论容量高、资源丰富以及对环境友好等优点,成为最有应用前景的下一代锂离子电池负极材料之一.然而,由于生产工艺复杂、成本高昂,使得纳米级硅材料的制备受到限制.采用镁粉和气相二氧化硅作为还原剂和硅源,并在制备过程中巧妙地引入氯化钠作为吸热剂用以吸收镁热还原过程放出的热量,成功制备出平均粒径约25 nm的纳米硅,纳米硅的收率达82%.所制备的纳米硅晶粒细小,有优良的电化学性能,首次脱锂比容量超过1875 mAh·g-1,首次库伦效率高达85%.以0.6 A·g-1电流密度循环50次后,脱锂比容量仍可保持1007 mAh·g-1.
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