Silicon Cutting Waste Derived Silicon Nanosheets with Adjustable Native SiO2 Shell for Highly‐Stable Lithiation/Delithiation

Silicon is an excellent candidate for the next generation of ultra-high performance anode materials, with the rapid iteration of the lithium-ion battery industry. High-quality silicon sources are the cornerstone of the development of silicon anodes, and silicon cutting waste (SCW) is one of them while still faces the problems of poor performance and unclear structure-activity relationship. Herein, a simple, efficient, and inexpensive purification method is implemented to reduce impurities in SCW and expose the morphology of nanosheets therein. Furthermore, HF is used to modulate the abundant native O in SCW after thermodynamic and kinetic considerations, realizing the mechanical support for the internal Si in the form of an amorphous SiO2 shell. Afterward, SCNS@SiO2 -2.5 with a 1.0 nm thick SiO2 shell exhibits a reversible capacity of 1583.3 mAh g-1 after 200 cycles at 0.8 A g-1 . Ultimately, the molecular dynamics simulations profoundly reveal that the amorphous SiO2 shell is transformed into the extremely ductile Lix SiOy shell to ditch stress and relieve strain during the lithiation/delithiation process.