Synthesis of Si@C Anode Materials by PVP Coating of Nano-Silicon Waste

The nano-silicon waste produced by photovoltaic/Si-wafer cutting processes (e.g., diamond-wire sawing kerf waste) possesses extremely high recycling value, and converting it into commercial lithium-ion battery anodes holds great research significance. In this study, we pretreated silicon waste to remove excess impurities and prepared polyvinylpyrrolidone (PVP)- and NaCl-coated Si@C negative electrode materials using simple ball-milling and heat treatment processes. The carbon coating improved the electrochemical performance of the silicon waste. The Si@C-1:1:3 negative electrode with a composition ratio of 1:1:3 exhibited enhanced electrochemical performance. When cycling at 0.5 A g −1 for 300 cycles, the charge-specific capacity remained stable at 810.6 mAh g −1 , with a capacity retention rate of 63.1%. At high current density (3 A g −1 ), the material demonstrated significant rate performance, with capacity of 590.6 mAh g −1 . Due to the formation of stable structural carbon shell material by PVP carbonization, the material capacity was improved; at the same time, a small amount of nitrogen was added to enhance Li + transmission efficiency, and the surface generated a stable dendritic carbon layer to provide more transmission sites for Li + , which significantly improved the conductivity and capacity characteristics. This work provides a simple and feasible method for preparing lithium-ion battery anodes from silicon waste.