Diatomite-Derived Hierarchical Porous Crystalline-AmorphousNetwork for High-Performance and Sustainable Si Anodes

Silicon has attracted considerable interest as a high-capacity anode material for next-generation lithium-ion batteries. However, Si-based anodes suffer extreme volume change (approximate to 380%) upon lithiation and delithiation, which results in rapid capacity fading due to mechanical and electrochemical failure during cycling. Herein, a sustainable and scalable method to synthesize hierarchically porous micron-sized Si particles from the low-cost diatomite precursor is reported, which serves as both the precursor and the template. Through a one-step magnesiothermic reduction, the SiO(2)constituent in diatomite is reduced to form a Si/SiO(2)composite network with 10-30 nm crystalline Si domains embedded within an amorphous SiO(2)matrix. Controlling the reduction time leads to an optimal ratio between the crystalline Si and the amorphous SiO(2)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/SiO(2)as the anode and LiNi(0.8)Co(0.1)Mn(0.1)O(2)as the cathode shows approximate to 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.