Vapor-phase conversion of waste silicon powders to silicon nanowires for ultrahigh and ultra-stable energy storage performance

Silicon nanowires (SiNWs) have been used in a wide variety of applications over the past few decades due to their excellent material properties. The only drawback is the high production cost of SiNWs. The preparation of SiNWs from photovoltaic waste silicon (WSi) powders, which are high-volume industrial wastes, not only avoids the secondary energy consumption and environmental pollution caused by complicated recycling methods, but also realizes its high-value utilization. Herein, we present a method to rapidly convert photovoltaic WSi powders into SiNWs products. The flash heating and quenching provided by carbothermal shock induce the production of free silicon atoms from the WSi powders, which are rapidly reorganized and assembled into SiNWs during the vapor-phase process. This method allows for the one-step composite of SiNWs and carbon cloth (CC) and the formation of SiC at the interface of the silicon (Si) and carbon (C) contact to create a stable chemical connection. The obtained SiNWs-CC (SiNWs@CC) composites can be directly used as lithium anodes, exhibiting high initial coulombic efficiency (86.4%) and stable cycling specific capacity (2437.4 mA h g⁻¹ at 0.5 A g⁻¹ after 165 cycles). In addition, various SiNWs@C composite electrodes are easily prepared using this method.