Recycling Waste Al-Si Alloy for Micrometer-Sized Spongy Si with High Areal/Volumetric Capacity and Stability in Lithium-Ion Batteries

People are becoming more conscious of the necessity of sustainable development, and waste recycling is getting increased attention. As for the highly concerned Si in lithium-ion batteries (LIBs), the recycled nanoscale Si displays a small packing density that would impede its industrialization. Moreover, Si recycling commonly shows a lengthy process and specialized device usage, resulting in high energy/cost consumption and pollution. This study employs waste Al-Si alloy as raw materials and proposes a hypothermal chemical corrosion method to recycle and construct micrometer-sized spongy Si. The nanopores/nanoskeletons in the spongy Si and the amorphous carbon coating (Si@C) regulate electron/lithium ion transference, capacitance behavior, and structural stability to achieve high areal/volumetric capacity and cycling performance. The spongy Si@C anode delivers an areal and volumetric capacity of 1.13 mAh cm(-2) and 1909 mAh cm(-3) (0.05 C), respectively. Increasing mass loading further improves areal capacity to 2.52 mAh cm(-2) (0.1 mA cm(-2)) which retains 0.89 mAh cm(-2) after 100 cycles at 1.2 mA cm(-2). Furthermore, in the full-cell configuration, the initial energy density is 483 Wh kg(-1) at 0.5 C, and the capacity retention is 84% after 150 cycles at 2 C. This study provides novel insights into the efficient and economical fabrication of high-performance LIBs.