微米硅-石墨-碳负极的制备及在锂离子电池中的应用

Preparation and Application of Micro Silicon-Graphite-Carbon Anodes for Lithium-Ion Batteries

硅作为锂离子电池负极的理论比容量是商用碳材料的10倍以上,但是其在循环过程中的巨大体积变化会导致电池负极粉化,形成不稳定的固体电解质界面(SEI)膜,从而阻碍硅负极材料的实际应用。以价格低廉的微米硅作为原材料,石墨和聚丙烯腈作为碳源,采用球磨、液相包覆和热解的方法,制备了微米硅-石墨-碳(Si-G-C)复合材料。所制备的微米Si-G-C电极表现出优异的循环稳定性能和倍率性能,在500 mA/g的电流密度下,循环100次后仍有1 000 mA·h/g的高可逆比容量,容量保持率为67.75%。即使在1 A/g的大电流密度下,其循环100次后,可逆比容量也可达到873 mA·h/g。

The theoretical specific capacity of silicon as anodes for the lithium-ion batteries is more than 10 times that of commercial carbon materials for the lithium-ion batteries. However, its practical application is hindered by the huge volume fluctuation of silicon during the cycle, which leads to the crushing of the battery anodes and the instability of the solid electrolyte interphase(SEI) film. The micro silicon-graphite-carbon(Si-G-C) composite was prepared by the methods of ball milling, liquid phase coating and pyrolysis with low-cost micro-silicon as the raw material,and graphite and polyacrylonitrile as the carbon source. The prepared micro Si-G-C electrode shows excellent cycling stability and rate performance. The reversible specific capacity can be up to 1 000 mA·h/g after 100 cycles at a current density of 500 mA/g, and the capacity retention is 67.75%. Even at a high current density of 1 A/g, its reversible specific capacity of 873 mA·h/g can be obtained after 100 cycles.