A Galvanic Cell Etching of Silicon Kerf Waste for Porous Silicon Anodes and Their Performance

Porous modification is an effective strategy for mitigating the volume expansion of silicon anodes in lithium-ion batteries and improving their conductivity. However, their processes often have defects, such as environmental hazards and complexity. Herein, we propose an environmentally friendly galvanic cell etching strategy for producing a high-performance porous silicon anode from silicon kerf waste. The process was carried out in one step by constructing a galvanic cell: Si(s)|C(s)|LiCl-KCl-CuCl 2 (l)|Cu(s) at 400°C. The prepared porous silicon anode delivered a high specific capacity of 704.74 mAh·g –1 at 2.0 A·g –1 after 1000 cycles, demonstrating excellent cycling stability. In addition, an orthogonal experimental design was employed to evaluate the impact of key parameters on the silicon etching rate ( η ( t )). The results indicated that temperature ( T ) was the most significant factor, followed by CuCl 2 concentration ( C ) and etching time ( t ). The derived etching kinetic equation using the shrinking core model (radius: r ) is η ( t ) = 1 – exp [ – 0.306 · C 0.7612 · r – 1 · exp ( – 16308 8.314 T ) · t ] . This process leverages the potential difference between Cu and Si, eliminating the need for external power, presenting a promising pathway for valorizing silicon kerf waste into high-performance anode materials.