The nanostructuring of low-cost micro-sized silicon (mSi) is paramount to achieve the practical viability of deploying high-capacity Si anodes for lithium-ion batteries (LIBs). Conventional methods for converting mSi to nanoporous Si (nSi) involve low product yield, toxic chemical reagents, high energy consumption, etc. Herein, we report a self-driven alloying/dealloying approach to converting mSi to nSi in molten salts, where mSi alloys with Mg powders to generate Mg₂Si and, subsequently, the Mg₂Si dealloys in a Mg₂Si||Sn primary battery with the production of nSi at the negative electrode and the liquid Mg-Sn alloy at the positive electrode. Finally, the Mg-Sn decomposes to Mg gas and liquid Sn through a vacuum-distillation process. Taking the micro-sized Si kerf waste as an example, the pyrolytic carbon-coated (PCC) nSi delivers a capacity of 1080.2 mAh g⁻¹ at 1 A g⁻¹ after 1000 cycles with a capacity retention rate of 83.7%. Furthermore, a fabricated PCC-nSi-2||LiNi_0.6Co_0.2Mn_0.2O₂ (NCM622) full cell demonstrates a high energy density of 466 Wh kg⁻¹ as well as good cycling stability for 200 cycles. The improved Li-storage performance is attributed to the synergetic effects of the nanoporous Si and carbon coating. Overall, the self-driven nanostructuring approach along with the vacuum-distillation process maintains a high utilization of mSi, eliminates the use of toxic reagents, and keeps a closed-loop material circle, and thus offers an efficient and green pathway to valorize various mSi for making enhanced lithium-storage anodes.

低成本微米级硅（mSi）的纳米结构对于实现为锂离子电池（LIB）部署高容量Si阳极的实际可行性至关重要。将mSi转换为纳米多孔Si（nSi）的常规方法涉及低产品产率，有毒化学试剂，高能耗等。在此，我们报道了一种自驱动合金化/脱合金方法，可将熔融盐中的mSi转换为nSi，其中mSi合金用Mg粉末生成的Mg ₂ Si和，随后，所述Mg ₂的Si dealloys在镁₂Si || Sn一次电池，负极生成nSi，正极生成液态Mg-Sn合金。最后，Mg-Sn通过真空蒸馏过程分解为Mg气和液态Sn。以超细碎屑为例，经过1000次循环后，热解碳涂层（PCC）nSi在1 A g ^-1下的容量为1080.2 mAh g ^-1，容量保持率为83.7％。此外，制成的PCC-nSi-2 || LiNi _0.6 Co _0.2 Mn _0.2 O ₂（NCM622）全电池显示出466 Wh kg ^-1的高能量密度以及200次循环的良好循环稳定性。锂存储性能的提高归因于纳米多孔硅和碳涂层的协同作用。总体而言，自驱动纳米结构化方法与真空蒸馏过程一起保持了mSi的高利用率，消除了有毒试剂的使用，并保持了闭环的材料循环，从而提供了一种有效且绿色的途径来增值各种mSi用于制造增强型锂存储阳极。