Beads-Milling of Waste Si Sawdust into High-Performance Nanoflakes for Lithium-Ion Batteries

Nowadays, ca. 176,640 tons/year of silicon (Si) (>4N) is manufactured for Si wafers used for semiconductor industry. The production of the highly pure Si wafers inevitably includes very hightemperature steps at 1400-2000 °C, which is energy-consuming and environmentally unfriendly. Inefficiently, ca. 45-55% of such costly Si is lost simply as sawdust in the cutting process. In this work, we develop a cost-effective way to recycle Si sawdust as a high-performance anode material for lithiumion batteries. By a beads-milling process, nanoflakes with extremely small thickness (15-17 nm) and large diameter (0.2-1 μm) are obtained. The nanoflake framework is transformed into a highperformance porous structure, named wrinkled structure, through a self-organization induced by lithiation/delithiation cycling. Under capacity restriction up to 1200 mAh g^-1, the best sample can retain the constant capacity over 800 cycles with a reasonably high coulombic efficiency (98-99.8%).