Reconstructed Nano-Si Assembled Microsphere via Molten Salt-Assisted Low-Temperature Aluminothermic Reduction of Diatomite as High-Performance Anodes for Lithium-Ion Batteries

Silicon (Si), as a promising candidate anode material of lithium-ion batteries (LIBs), is going to have large-scale applications. Its high theoretical specific capacity, low lithiation potential, and natural abundance can meet the consumer expectation for the high energy density and cycle life of LIBs. At present, the huge volume change and very high manufacturing costs also hinder its wide applications. Therefore, preparation of Si material using abundant siliceous rocks in earth and reasonable structure design are important strategies to solve the problems. Here, we report a new nano/microstructure of Si microsphere assembled by nano-Si via molten salt-assisted low-temperature aluminothermic reduction of diatomite. The use of abundant diatomite can reduce the synthetic cost of Si. Moreover, the molten salt-assisted low-temperature aluminothermic reduction can significantly lower the synthesis temperature and energy consumption to further reduce the cost. More importantly, the new nano/microstructure of Si microsphere can disperse expansion stress in local nanocrystalline area compared to the bulk perfect crystalline Si. As the anode of LIBs, the electrode exhibits good cycle stability and can deliver a reversible capacity of 1330.1 mAh g–1 after 200 cycles at 0.2 A g–1. This work offers a cheap synthesis route to prepare new nano/microstructure and is significant for large-scale applications of Si materials.