(133a) Nature-Derived Nanostructures for Sustainable Si Anode in High-Energy Li-Ion Batteries

Silicon (Si) has attracted considerable interests as a high-capacity anode material for next-generation lithium-ion batteries. However, Si-based anodes suffer extreme volume change (~380%) upon lithiation and delithiation, which results in rapid capacity fading due to mechanical and electrochemical failure during cycling. In this talk, we report a sustainable and scalable method to synthesize hierarchically porous micron-sized Si particles from the low-cost diatomite precursor, which serves as both the precursor and the template. Through a one-step magnesiothermic reduction, the SiO₂ constituent in diatomite is reduced to form a Si/SiO₂ composite network with 10–30 nm crystalline Si domains embedded within an amorphous SiO₂ matrix. Controlling the reduction time leads to an optimal ratio between the crystalline Si and the amorphous SiO₂ constituent, which endows the composite structure with high capacity and excellent cycling stability. For example, 90% capacity can be retained after 500 cycles at 0.2C for sample reduced by 6 h without any coating or prelithiation. The full cell with such Si/SiO₂ as the anode and LiNi_0.8Co_0.1Mn_0.1O₂ as the cathode showed ~80% capacity retention after 200 cycles. This work creates a unique path towards sustainable and scalable production of high-performance micron-sized Si anodes, offering new opportunities for potential industrial applications.