球磨法制备煤沥青基高性能锂离子电池硅/炭负极材料

Preparation of coal tar pitch-based silicon/carbon anode materials for lithium ion batteries by ball milling

以煤沥青基软炭、纳米硅粉和壳聚糖为原料,通过机械球磨、热解制备了硅/炭复合材料,考查了不同原料配比对产品结构性能的影响。当软炭与壳聚糖质量比为4∶1时,Si/MSC/Ch-4展现了优异的储锂性能。在0.1 A·g-1的电流密度下,其首次可逆比容量为690.6 mAh·g-1,首次库伦效率为70.57%。即使在5 A·g-1的电流密度下,其比容量仍高达410 m Ah·g-1。在1 A·g-1的电流密度下循环200圈后其比容量为386 mAh·g-1。在球磨产生的机械力的作用下,软炭片层包覆在硅纳米颗粒表面缓解其体积膨胀并提高复合材料的导电性。壳聚糖衍生碳分散在复合材料体相中,连接硅纳米颗粒和软炭片层,进一步提高复合材料的结构稳定性。

The silicon/carbon composite is fabricated using coal tar pitch-based soft carbon, silicon nanoparticles(Si NPs) and chitosan as raw materials through ball milling and carbonization treatment. The effects of different mass ratio of raw materials on the structure and lithium storage performance of Si/C composites are investigated. When the mass ratio of soft carbon to chitosan is 4∶1,the Si/MSC/Ch-4 exhibits excellent lithium storage performance. The initial reversible capacity of the composite is 690.6 m Ah/g at 0.1 A/g with the initial coulombic efficiency(ICE) of 70.57%. Even at 5 A/g, the composite delivers capacity of 410 mAh/g. After 200 cycles at 1 A/g, the composite achieves capacity of 386 m Ah/g. Through mechanical ball milling, the soft carbon sheets coated on the Si NPs can relieve their volume expansion and improve electronic conductivity of the composite. The chitosan-derived carbon which disperses in the composite connects the Si NPs with soft carbon sheets thus increases the structural stability of the composite.