Scalable synthesis of nano-Si embedded in porous C and its enhanced performance as anode of Li-ion batteries

In the present work, the sample of Si nanoparticles embedded in porous C (denoted as Si@porous-C) has been successfully synthesized by using nano-MgO as the pore-former. Observations by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) on Si@porous-C sample reveal that Si nanoparticles homogeneously disperse in porous carbon scaffold. As anode of lithium ion battery (LIB), Si@porous-C preserves a charge-discharge capacity of 1172 mAh g⁻¹ after 40 cycles, possessing enhanced cyclic deterioration of only 0.35% per cycle in comparison with Si nanoparticles and Si nanoparticles embedded in ordinary carbon (denoted as Si@C). It delivers reversible capacities of about 947 mAh g⁻¹, 670 mAh g⁻¹, and 394 mAh g⁻¹ in current densities of 1000 mA g⁻¹, 2000 mA g⁻¹, and 4000 mA g⁻¹, respectively, all of which are higher than those of commercial nano-silicon and Si@C. The improved high-rate capability of Si@porous-C could be attributed to a decreased resistance and enhanced infiltration of electrolytic solution around nano-silicon particles. The merits of scalable synthetic process and improved electrochemical properties recommend Si@porous-C as a promising anode material for high performance Li-ion batteries.