Waste to Wealth: S,N-Codoped Si/C Anode Derived from Waste Tire Oil Exhibits Superior Performance in Lithium-Ion Batteries

Integrating silicon (Si) nanoparticles with carbonous materials has been regarded as an effective strategy to suppress the serious volume expansion and poor electrical conductivity of the Si anode in lithium-ion batteries (LIBs). Herein, the Si/C composite coated with a S,N-codoped graphene layer (Si@SNG) has been prepared via a facile and easily scale-up strategy that combines the vertical fluidized-bed-derived chemical vapor deposition in which the lightweight waste tire pyrolysis oil with high S content and pyridine is utilized as carbon source and dopants. The introduction of S,N-codoped graphene layer and graphite matrix can effectively increase Li⁺ storage room and conductivity, while buffering the volume expansion of pure Si. As result, the Si@SNG anode delivers a high initial Coulombic efficiency (ICE) of 86.91%, large specific capacity of 2446 mAh g^-1 at 0.3 A g^-1 and 90.3% capacity retention rate for 600 cycles within 0.01-1 V. In addition, the Si@SNG@G-P composite containing Si@SNG (10 wt %) and graphite matrix (90 wt %) has been prepared by ball milling and liquid-phase coating. As the anode, Si@SNG@G-P exhibits a high specific capacity of 695 mAh g^-1 at 0.05 A g^-1 coupled with 94.6% capacity retention rate for 500 cycles within 0.01-2 V. Moreover, the full cell assembled by Si@SNG@G-P anode and LiFePO₄ cathode shows a high specific capacity of 157.7 and 128 mAh g^-1 at 0.2 and 4 C, 93.1% capacity retention for 200 cycles along with a high energy density of 257.3 Wh kg^-1. Therefore, this work offers a low-cost and high-efficiency preparation strategy for obtaining Si-based materials with outstanding electrochemical performance in LIBs.