Recycling silicon scrap for spherical Si–C composite as high-performance lithium-ion battery anodes

The growth of the semiconductor and solar industry has been exponential in the last two decades due to the computing and energy demands of the world. Silicon (Si) is one of the main constituents for both sectors and, thus, is used in large quantities. As a result, a lot of Si waste is generated mainly by these two industries. For a sustainable world, the circular economy is the key; thus, the waste produced must be upcycled/recycled/reused to complete the circular chain. Herein, we show that an upcycled/recycled Si can be used with carbon as a composite anode material, with high Si content (∼40 wt%) and loading of 3–4 mAh/cm2 for practical use in lithium-ion batteries. The unique spherical jackfruit-like structure of the Si–C composite can minimize the total lithium inventory loss compared to the conventional Si–C composite and pure Si, resulting in superior electrochemical performance. The superior electrochemical performance of Si–C composites enables the cell energy density of ∼325 Wh kg−1 (with NMC cathode) and ∼260 Wh kg−1(with LFP cathode), respectively. The results demonstrate that Si-based industrial waste can be upcycled for high-performance Li-ion battery anodes through a controllable, scalable, and energy-efficient route.