Magnesiothermic Reduction Synthesis of C@Si Composite from Fly Ash Cenospheres As High-Performance Anode Materials for Lithium-Ion Batteries

Silicon-based materials have emerged as prime candidates for next-generation lithium-ion battery anodes owing to their exceptional theoretical capacity. Limited by the inherent defects and high price of pure silicon, the practical application to lithium-ion battery anodes is a major challenge. Herein, porous silicon anode materials were successfully converted via magnesiothermic reduction using cost-effective and abundant fly ash cenospheres (FACs) as the precursor, and C@Si composite materials were further synthesized using phenolic resin as the carbon source to enhance electrochemical performance. The porous structure of silicon promotes lithium-ion transport, and the carbon layer provides mechanical support for silicon. The structurally optimized C@Si-FAC anode delivers exceptional performance metrics with 526 mAh center dot g- 1 reversible capacity at 50 mA center dot g- 1, sustains 346 mAh center dot g- 1 rate capability at 2000 mA center dot g- 1 and 47 % capacity retention after 100 cycles. This study provides a low-cost approach for preparing high-performance silicon-based materials for lithium-ion batteries and promotes the high-value application of solid waste.