Porous Si@C Nanosheets Derived from Photovoltaic Si Waste as a High-Performance Anode Material for Lithium-Ion Batteries

Si has been considered to be one of the most promising anode materials for the next-generation lithium-ion batteries due to its apparently high theoretical specific capacity, moderate operating voltage, and abundant availability. However, its practical application is hindered by significant volume expansion and poor dynamic performance. To break through these limitations, the porous Si@C nanosheets, which were prepared from photovoltaic Si waste via alloying and CO2 thermic-oxidation process, were proposed in this work. Based on the pristine 2D nanosheet structure of Si waste, a simultaneous bulk porosity engineering and carbon-coating process was adopted to provide additional buffering for volume expansion while constructing more efficient ionic and electronic transport channels. Benefiting from the unique structure, the porous Si@C nanosheets demonstrate an outstanding cycling stability (high reversible specific capacity of 786.4 mA h g–1 at 1 A g–1 after 750 cycles) and a large rate capability (specific capacity of 879 mA h g–1 at 5 A g–1).