Si/C composite embedded nano-Si in 3D porous carbon matrix and enwound by conductive CNTs as anode of lithium-ion batteries

Abstract

Silicon (Si) is served as next generation prospective anode material for lithium-ion batteries (LIBs) on account of the high theoretical capacity (about 4200 mAh g−1), suitable working voltage, and abundant resources. Nevertheless, the structural collapse during the repeated charge-discharge process and lower electrical conductivity severely hinder the commercial application of the Si anode. Combining with carbon components is an effective and feasible way to address these drawbacks. Herein, we design and construct a composite architecture based on nano Si embedded into three-dimensional porous N-doped carbon (p-NC) and then combine with carbon nanotubes (CNTs) via NaCl template-assisted in-situ pyrolysis strategy. The results show that the porous structure of the p-NC has a binding effect on Si nanoparticles, which can effectively relieve the volume variation, maintain structural stability, and increase the ion/electron diffusion rate. And the CNTs further ensure rapid lithium ion (Li+) diffusion and electron transfer. Therefore, the introduction of p-NC and CNTs allows the Si anode to greatly improve the electrochemical performance of lithium storage. The Si/p-NC/CNTs shows a satisfactory initial discharge of 1510.9 mAh g−1 at 0.3 A g−1, and it can still maintain a high capacity of 1126.3 mAh g−1 after 100 cycles.