Upcycling of Photovoltaic Silicon Waste via Molten Salt Electrolysis for the Synthesis of High‐Performance Silicon Nanowire Anodes

ABSTRACT Silicon‐based anode materials are considered promising candidates for high‐capacity lithium‐ion batteries, but their practical application has been hindered by significant volumetric expansion during cycling. This study introduces an innovative strategy that utilizes the naturally fine particle size and surface‐oxidizable properties of silicon cutting waste (SiCW) to synthesize silicon nanowires (SiNWs) via a precisely controlled two‐step constant‐voltage molten salt electrolysis process. Experimental results indicate that the electrical double‐layer effect enhances the ordered deposition of silicon atoms during electrolysis, while the solid–liquid–solid (SLS) mechanism regulates the directional growth of SiNWs by facilitating nucleation and crystal growth. The resulting SiNWs anode demonstrates an exceptionally high initial discharge capacity of 3519.6 mAh·g − ¹ at 0.5 A·g − ¹, with an initial Coulombic efficiency of 86.7%, while maintaining a reversible capacity of 1071.5 mAh·g⁻¹ after 300 cycles. In addition to offering a sustainable upcycling approach for photovoltaic SiCW, this work clarifies the structure–performance relationship involving voltage modulation, morphological evolution, and electrochemical behavior, providing crucial insights for the rational design and targeted synthesis of SiNWs.