Green utilization of silicon slime: recovery of Si and synergetic preparation of porous silicon as lithium-ion battery anode materials

With the flourishing development of the photovoltaic industry, the waste of silicon slime generated by photovoltaic cutting has been a serious environmental problem, along with silicon resource waste. In this paper, the waste silicon slime produced by the photovoltaic industry was used as raw materials. Porous silicon particles were synthesized with the magnesium thermal reduction method, combined with hydrofluoric acid etching. The porous silicon can be applied to be the anode material of lithium-ion batteries. The synergistic effect of magnesium thermal reduction and acid etching on the preparation of porous silicon materials was studied. A lower heating rate of 5 °C/min will result in less heat accumulation, which can avoid the formation of large-sized Si/MgO composite particles and obtain a well-dispersed morphology. After a current density of 100 mA·g−1, the reversible capacity of porous silicon anode is 751.1 mAh/g after 50 cycles. Compared with commercial nano silicon, its cycle stability and cycle performance have been improved, which provides a new approach for green reutilization of waste silicon slime in the photovoltaic industry.