High-Performance Silicon–Carbon Materials with High-Temperature Precursors for Advanced Lithium-Ion Batteries

In silicon–carbon (Si-C) anode materials fabricated via chemical vapor deposition (CVD), the pore size distribution of porous carbon is a critical parameter that strongly affects the overall electrochemical performance. In this study, biomass-derived hard carbon was employed as the precursor, and porous carbon materials with distinct pore size characteristics were prepared via fluidized bed porosimetry after carbonization at different temperatures. Based on these porous carbon substrates, three types of Si-C anodes corresponding to low-, medium-, and high-temperature treatments were synthesized through a combination of SiH4 deposition and carbon coating processes. Electrochemical evaluation demonstrated that all three Si-C anodes exhibited favorable electrochemical performance and suppressed volume expansion. Among them, the Si-C anode prepared at a medium temperature of 1100 °C, denoted as NT-P-SC, delivered the most balanced performance, achieving an initial coulombic efficiency of 94.47% together with excellent rate capability. Furthermore, when Si-C anodes derived from different porous carbon matrices were blended with graphite to achieve a composite capacity of 500 mAh/g and evaluated in full-cell configurations, the NT-P-SC silicon-based composite exhibited superior cycling stability. The composite delivered an initial discharge capacity of 3.53 mAh and maintained a capacity of 2.74 mAh after 1628 cycles, corresponding to a capacity retention of 77.62%. The improved electrochemical performance of the Si-C anode is primarily attributed to the optimized pore structure of the porous carbon matrix synergistically combined with the carbon coating process.