Fabrication of Porous Si@C Composites with Core-Shell Structure and Their Electrochemical Performance for Li-ion Batteries

The pores in silicon particles can accommodate the volume expansion of silicon during the charging-discharging process. However, pores in silicon particles are easily occupied by carbon during the preparation of silicon/carbon composites. In this paper, sulfur was adsorbed in the pores of porous silicon particles before polyaniline (PANI) coating by in-situ polymerization, so that the pores were preserved in porous silicon@carbon (p-Si/@C) composites after the sublimation of sulfur during carbonization. The microstructure and the electrochemical performances of the obtained p-Si/@C composites were investigated. The results indicate that p-Si/@C composites prepared with a sulfur-melting process show a better high-rate performance than those without a sulfur-melting process. Remarkably, the former show a better capacity retention when returning to a low current density. The reversible capacities of the former were 1178 mAh.g(-1), 1055 mAh.g(-1), 944 mAh.g(-1), and 751 mAh.g(-1) at 0.2 A.g(-1), 0.3 A.g(-1), 0.5 A.g(-1), and 1.0 A.g(-1), respectively. Moreover, the reversible capacities could return to 870 mAh.g(-1), 996 mAh.g(-1), and 1027 mAh.g(-1) when current densities returned to 0.5, 0.3, and 0.2 A.g(-1), respectively.