Upcycling FCC slurry via in-situ SiCl₄-catalyzed polycondensation: Constructing core-shell Si@C composites for high-stability lithium storage

Petroleum-based polycyclic aromatic hydrocarbons (PAHs), as by-products of petroleum, offer the advantages of abundant availability and high carbon content, making them ideal high-quality raw materials for the fabrication of carbon anode materials in lithium batteries (LIBs). This study presents a novel, dual-purpose strategy to fabricate hollow core-shell silicon-carbon composites (Si@Void@Cx) via the in-situ catalytic polycondensation of Fluid Catalytic Cracking (FCC) slurry. Unlike traditional synthesis routes employing metallic Lewis acids (e.g., AlCl₃, FeCl₃), silicon tetrachloride (SiCl₄) was used as a cleaner, bifunctional catalyst that avoids metallic contamination while facilitating the precise polymerization of the carbon matrix. This approach not only circumvents the integration of heteroatoms via the catalyst, but also simplifies the process flow, reduces energy consumption, and contributes to a greener, sustainable technology by enhancing the high-value utilization of FCC, benefiting both resource conservation and environmental protection. The optimized composite (Si@Void@C1) delivers a robust electrochemical performance, exhibiting a specific capacity of 601.9 mAh/g and maintaining electrode integrity with a negligible thickness expansion of only 7% after 1000 cycles. Si@Void@C1 capitalizes on the well-dispersed silicon (Si) nanoparticles and the intact hollow core-shell structure to effectively buffer against the volume expansion stress of Si, thus maintaining electrode structural integrity and achieving superior cycling performance. This work provides a scalable, sustainable pathway for transforming petrochemical byproducts into advanced energy storage materials.