Recycling of micron-sized Si powder waste from diamond wire cutting and its application in Li-ion battery anodes

Abstract Approximately 40 wt%–60 wt% of the micron-sized Si powders in the form of slurry is wasted because the surface of powders is polluted during diamond wire cutting in the photovoltaic industry. This study proposes a series of chemical treatments for recycling Si powder waste by removing impurity layers on the surface of Si powders, and applying the recycled Si powders to the anode material of Li-ion battery. The results demonstrate the effective removal of the outermost Si oxide and organic fouling layers on the surface of Si powders through treatments. The concentration of organic impurities decreased from 1420 ppmw to 800 ppmw. The concentration of metal impurities also decreased from 100.36 ppmw to 32.75 ppmw after the purification. The best electrical performance of Si/C composites obtained using recycled Si powders reached 426.1 mAh·g−1 after 450 cycles, a clear improvement compared with that of Si/C composites without chemical treatments. Recycling micron-sized Si powder waste provides an inexpensive feedstock for Si-based Li-ion battery anodes from the perspective of cost and environmental sustainability.