Engineered pitch-pyrolyzed carbon-coated porous Si/SiOx/needle coke nanocomposites as anode material for enhanced lithium-storage performance
A unique core–shell structured pitch-pyrolyzed carbon-coated porous Si/SiO x /needle coke (Si/SiO x / NC@C) nanocomposite has been successfully synthesized via a low-temperature aluminothermic reduction combined with a scalable spray-drying and following carbonization processes. The fabrication of silicon-based materials in Si/SiO x /NC@C nanocomposites derived from high silica-containing silica fume powders enables effective utilization of industrial solid waste. The Si/SiO x nanoparticles in Si/SiO x /NC@C with abundant internal nanovoids are anchored on the surface of needle coke matrices, forming Si/SiO x -needle coke dual-phase cores, which are wrapped by a thin pitch-pyrolyzed amorphous carbon layer. The synergetic combination of these inherent advantages, such as high electroconductivity, porosity, amorphous/crystalline mixture structure, and high-valence SiO x residues, remarkably enhances the composite’s structural stability and buffers internal structure stress induced by alloying/dealloying of Si. The Si/SiO x /NC@C nanocomposites demonstrate exceptional electrochemical stability, exhibiting a specific reversible capacity of 771.5 mAh g⁻ 1 with minimal capacity decay (~ 0.06% per cycle) over 500 cyclic repetitions at an elevated current density of 200 mA g⁻ 1 . Rate capability tests show that the Si/SiO x /NC@C nanocomposites achieve a high capacity of 660.25 mAh g −1 even when subjected to the highest current of 3200 mA g −1 . More notably, this work provides a facile and promising economical route for the scalable industrial production of high-performance Si-needle coke anode materials for future LIBs from industrial solid waste.
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