Facile Fabrication of Porous Si Microspheres from Low-Cost Precursors for High-Capacity Electrode

Comparing with nanometer-sized Si (nano-Si), the micrometer-sized Si (micro-Si) is more promising for the practical applications due to its low cost and scalable production method. Fabrication of micro-Si with porous architecture can efficiently alleviate the high mechanical stress and severe mechanical fracture. Till now, it is still a challenge to achieve porous micro-Si with controlled morphology, such as microsphere, from a cost-efficient and environmentally friendly approach. Herein, a facile approach on fabricating Si microsphere with porous architecture via a low-temperature aluminothermic reduction (LTAR) method using the low-cost fumed silica (FS) as raw material is introduced. After compositing with graphite and then coating with amorphous carbon, the Si-FS/graphite@carbon (Si-FS/G@C) electrode displays superior reversible capacity (730 mAh g(-1) after 100 cycles) and excellent rate capability (729.1 mAh g(-1) at 1 A g(-1)). The electrochemical performance is much better than that of Si-microparticles/G@C (Mic-Si/G@C, 368 mAh g(-1) at 100 mA g(-1) after 100 cycles). These results show the great potential of Si-FS/G@C electrode as an alternative high-performance electrode material for lithium ion batteries. Moreover, the LTAR adopted in the current study significantly reduces the energy consumption for preparation of Si microspheres from low-cost raw materials.