Modeling Silane Deposition in Nanoporous Carbon for High-Capacity Si/C Composite Anodes

Abstract

Si/nanoporous carbon composites are promising anode materials for high-energy-density lithium-ion batteries. Chemical vapor deposition of Si into nanoporous carbon is an efficient approach to synthesize high-performance Si/nanoporous carbon composites. While attractive performance has been demonstrated experimentally, there is a lack of modeling work to understand how experimental conditions and carbon properties affect deposition geometry and uniformity. This study aims to develop a general model of chemical vapor deposition of silicon into nanoporous carbon in a tube furnace, which describes key processes such as advection, diffusion, and reaction kinetics. Various parameters such as temperature, pressure, tube length, flow rate, surface area, and pore size were investigated to determine their effects on deposition uniformity and filling portion along the tube. The simulation results align with experimental results reasonably. The model predicts that lower temperature, lower pressure, higher flow rate, less carbon loading, and lower specific surface area favor better uniformity across the whole tube furnace. This work provides valuable insights for optimizing the operating conditions in tube reactors and can contribute to the advancement of deposition processes.