Upcycling photovoltaic silicon waste into SiO anode materials

Abstract

Silicon monoxide (SiO) is one of the most widely applied silicon-based anode materials for commercial lithium-ion batteries. However, conventional high-temperature vacuum solid–phase synthesis suffers from low conversion efficiency (<80%) and sluggish reaction kinetics, leading to an unfavorable cost-to-performance ratio of SiO anodes. In this work, photovoltaic-cutting waste silicon powder was utilized as a sustainable alternative to conventional micron-sized silicon (8–10 μm) for the efficient synthesis of SiO. The ultrafine particle size (∼0.3 μm) and high chemical reactivity of the waste silicon powder markedly accelerated the solid–phase reaction, thereby enhancing both the reaction rate and conversion efficiency. The migration and transformation behaviors of metallic impurities within the waste silicon powder, as well as their effects on SiO conversion efficiency, were systematically elucidated. This synthesis strategy achieved a high SiO conversion rate exceeding 95% and delivered excellent cycling stability when applied to lithium-ion battery anodes. Moreover, the as-prepared anode, even without surface modification, maintained a reversible specific capacity above 580 mAh g⁻¹ after 200 cycles at 0.5 A g⁻¹. The successful implementation of this strategy not only enables the high-value utilization of photovoltaic waste silicon powder and the efficient synthesis of SiO, but also offers a feasible and sustainable pathway toward the low-cost, green, and scalable industrial production of SiO.