Optimized Porous Si/SiC Composite Spheres as High-Performance Anode Material for Lithium-Ion Batteries

Fabricating porous Si via magnesiothermic reduction is an effective way to tackle the volume expansion of Si anodes. However, the agglomeration of Si due to the local heat accumulation during the thermal reduction process severely limits its lithium storage capacity. Here, we propose a simple approach to synthesize optimized porous Si/SiC composite (pSi/SiC) spheres via modifying the precursor SiO₂ of magnesiothermic reduction. After heat treatment process, in-situ generated SiC uniformly dispersed among silicon nanoparticles, playing a crucial role in decreasing local heat accumulation, sequentially maintaining the stability of the porous spherical structure. This method not only optimized pore distribution of porous Si, but also enhanced the buffer effect of SiC. Finally, the as-prepared pSi/SiC exhibits superior lithium storage performance (1653.4 mAh g⁻¹ and 1446.7 mAh g⁻¹ at 0.5 A g⁻¹ and 1 A g⁻¹ after 100 cycles, 1022 mAh g⁻¹ at 2 A g⁻¹ after 400 cycles, and 420 mAh g⁻¹ at 5 A g⁻¹ even after 2000 cycles). This work can provide an inspirational idea to prepare other optimized porous Si-based anode materials through introducing various buffer materials.