Optimization of Porous Structure on Carbon Host for Silicon/Carbon Anodes in High-Capacity Lithium-Ion Batteries

Silicon (Si), one of the most promising anode materials for high-energy-density lithium-ion batteries (LIBs), faces commercialization challenges due to its significant volume variation during cycling. Embedding amorphous silicon nanoparticles (SiNP) into a porous carbon host has emerged as an effective strategy to mitigate this issue, particularly through the recently developed chemical vapor deposition (CVD) route using silane as a precursor. The structural properties of the carbon framework─such as pore size, pore volume, and surface area─play a critical role. In this study, three types of model carbon hosts were employed: zeolite-templated carbon (ZTC) with monodisperse micropores, CMK-3 with uniform 4.9 nm mesopores, and ordered mesoporous carbon (OMC-8) featuring monodisperse 8.3 nm mesopores. The influence of the porous structure of the carbon host on the performance of the silicon/carbon (Si/C) anodes was systematically investigated. The results demonstrate that microporous structures facilitate higher pore utilization efficiency for silicon loading, leading to high specific capacity, excellent rate performance, and superior cyclic stability. When evaluated as an anode for LIBs, the carbon-coated Si embedded in ZTC (C@Si@ZTC) electrode delivers an ultrahigh specific capacity of 2175 mAh g–1 with an initial Coulombic efficiency (ICE) of 87.48% at 0.1C. After 200 charge/discharge cycles at 0.2C, it retains a reversible capacity of 1825 mAh g–1. Furthermore, in a cylindrical 18650 battery configuration (C@Si@ZTC/graphite||NCM811), the battery exhibits a capacity of 2143 mAh and maintains 92.4% capacity retention after 400 cycles at 1C.