Kinetically accelerated molten-salt synthesis of porous silicon/carbon core-shell anodes for lithium batteries

Developing silicon anodes with high energy and rate capability for lithium-ion batteries (LIBs) is limited by severe volume expansion and sluggish kinetics. Herein, we demonstrate a low-temperature molten-salt aluminothermic reduction (MS-ATR) process using Al-AlCl₃ system to synthesize porous silicon (pSi) particles from a high-silica zeolite precursor below 300 °C. Reduction kinetics modeled via the Ginstling-Brounstein (GB) 3D diffusion model demonstrate that a dynamic rotary reactor configuration (MS-ATR-d) significantly enhances mass transfer and reduction rates compared to a static setup (MS-ATR-s). At 270 °C, MS-ATR-d achieves a 1.7-fold higher rate constant than MS-ATR-s, resulting in substantially increased pSi yield. The apparent activation energy for MS-ATR-d is estimated at 86.0 kJ mol^-1, notably lower than that for magnesiothermic reductions. The resulting pSi replicates the precursor morphology, featuring primary silicon nanoparticles (30-50 nm) and a distinct mesoporous network. After carbon coating, the core-shell pSi/C composite anode demonstrates an initial charge capacity of 1320 mAh g^-1 at 50 mA g^-1, a superior initial coulombic efficiency of 84.6%, and excellent long-term cycling stability, vastly outperforming commercial solid silicon nanoparticle/carbon (SiNP/C) control. These results establish MS-ATR-d process as an efficient, kinetically enhanced pathway to high-performance silicon anodes.