High-value utilization of slag-derived TiO2 enabled by heterostructured shell encapsulation of nano-Si

Abstract: In response to the dual-carbon strategy's demand for high-value utilization of metallurgical solid waste, this study innovatively employs a titanium solution obtained from hydrometallurgical titanium extraction of blast furnace slag as a titanium source. To address the challenge of its difficult direct hydrolysis in acidic systems, a solvothermal process was developed to firmly anchor blast furnace slag-derived titanium dioxide (BFS-TiO2) nanoparticles onto the surface of nano-Si, forming a Si/TiO2 heterointerface. Further encapsulation with a phenolic resin-based carbon layer constructed the heterostructured core-shell nanocomposite (Si@BFS-TiO2/C). The BFS-TiO2/C heterostructured shell not only effectively accommodates the severe volume expansion of the nano-Si core to mitigate pulverization but also establishes multimodal pathways for efficient charge transport. As a lithium-ion battery anode, the electrode demonstrated excellent electrochemical performance, delivering an initial discharge capacity of 2066.8 mAh·g−1 with an initial coulombic efficiency (ICE) of 74.56%. After 100 cycles at a high current density of 2 A·g−1, it maintained a specific capacity of 1283.6 mAh·g−1, corresponding to an 80.91% capacity retention rate. This study provides new insights into the utilization of high-value resources in metallurgical solid waste and the development of high-performance silicon-based anodes.