Sustainable Upcycling of Solar Silicon Waste Into Hierarchical Silicon‐Based Nanofibers Embedded With Quantum Dots for Ultra‐Stable Silicon Anodes

Silicon (Si) anodes, while theoretically surpassing graphite in capacity, face commercialization challenges from inherent volume fluctuations (>300%) and costly nano‐engineering processes. This study presents a sustainable solution through photovoltaic silicon waste upcycling into structurally optimized silicon/carbon (Si/C) nanofibers with Nb 2 O 5 ‐mediated interfacial chemistry. The designed architecture features a 3D continuous carbon network enabling efficient stress redistribution during lithiation and Nb 2 O 5 quantum dots embedding within the outer layer that dual‐functionalizes as both hydrogen fluoride (HF) corrosion inhibitor and Li⁺ diffusion promoter. Electrochemical characterization reveals stabilized solid electrolyte interphase (SEI) due to the robust 3D network and suppress HF attack by Nb 2 O 5 quantum dots. Benefiting from the enhanced structural stability and interfacial compatibility, the resultant Nb 2 O 5 ‐engineered Si/C anode achieves 77.3% initial Coulombic efficiency with 780 mAh g −1 retention after 1000 cycles at 1.0 A g −1 (0.023% capacity decay per cycle), outperforming state‐of‐the‐art recycled Si anodes in both cyclability and cost‐effectiveness. This study pioneers a dual‐approach strategy that simultaneously establishes a sustainable upstream silicon source through photovoltaic waste valorization and resolves the persistent challenges of cyclic volumetric expansion and interfacial instability inherent to silicon anodes.