纳米Si掺杂SiOx-Si@C@碳纳米管复合负极材料的制备及性能

在对氧化亚硅(SiO)材料进行表面碳包覆和添加导电材料的基础上，掺杂少量纳米Si进一步提高其首次充放电容量和首次库仑效率。采用XRD、SEM、TEM、Raman、FTIR分析材料的物相结构和微观形貌，通过恒流充放电测试仪分析复合材料的电化学性能。结果显示，纳米Si质量为SiO_x质量10%的复合材料(SiO_x-Si@C@碳纳米管(CNTs)-10)的首次充放电容量分别为1 348.1 mA?h/g和1 874.4 mA?h/g，首次库仑效率为71.9%，循环100周后材料的可逆容量为1 116.2 mA?h/g，容量保持率为82.8%；以不同电流密度充放电，其放电容量远远高于没有纳米Si掺杂的材料。SiO_x-Si@C@CNTs复合材料具有较高的首次库伦效率、较好的循环性能和倍率性能。 

Preparation and properties of nano-Si doped SiOx-Si@C@carbon nanotubes composite anode materials

Based on the carbon coating and addition of conductive materials, a small amount of nano-Si was doped to further improve the first charge and discharge capacity and the first coulombic efficiency. The phase structure and micromorphology of the materials were analyzed by XRD, SEM, TEM, Raman and FTIR, and the electrochemical properties of the composites were analyzed by a constant current charge-discharge test. The results show that the composites with 10% nano-Si (SiO_x-Si@C@carbon nanotubes(CNTs)-10) exhibit a first charge and discharge capacity of 1 348.1 mA?h/g and 1 874.4 mA?h/g, respectively, with the first coulombic efficiency of 71.9%. After 100 cycles, the reversible capacity of the composite is 1 116.2 mA?h/g, with the capacity retention rate of 82.8%. The discharge capacity is much higher than that of the material without nano-Si doping at different current densities. The SiO_x-Si@C@CNTs composites show high first coulombic efficiency, good cycle performance and rate performance.