Fluidization synthesis of silicon-nanocrystals embedded mesoporous carbon for high-performance lithium-ion batteriess

Abstract

Silicon carbon (Si/C) composites are widely regarded as leading anode candidates for high-energy-density power batteries in the path toward commercialization. However, the conventional preparation processes of nano-Si/carbon composites still face challenges such as severe agglomeration and uneven distribution of nano-Si, insufficient conductive interface contact, and severe volume expansion during cycling. In this work, we propose a strategy for the fabrication of Si-nanocrystal/carbon composites by sequential fluidized chemical vapor deposition (CVD) of silane (SiH₄) and acetylene (C₂H₂) within porous carbon materials. Taking advantage of the high-temperature decomposition of SiH₄, nano-sized Si-crystallites (<5 nm) are uniformly deposited inside the porous carbon matrix, which enhances the interfacial contact in Si/C composites and improving the electron/ion transport kinetics. An optimally regulated C₂H₂-derived carbon coating further stabilizes the electrode structure and effectively mitigates the volume expansion of Si. Meanwhile, the fluidized engineering approach strengthens the mass transfer rate during the fabrication process, thereby shortening the manufacturing time and improving the uniformity of Si-nanocrystal deposition. The as-prepared Si-nanocrystal/carbon composites, when applied as anode materials for lithium-ion batteries, exhibit excellent electrochemical performance. The composite delivers an initial coulombic efficiency (ICE) of 76 % at a current density of 0.3 A g⁻¹ and maintains a reversible capacity of 733.6 mAh g⁻¹ after 100 cycles. The effective adoption of this approach provides a novel route toward the commercialization of Si/C anode materials.