Engineering High-Rate Anode Materials via Montmorillonite-Derived Silicon Nanosheets

2D Silicon (Si) based materials are promising high-rate anode candidates due to the short Li⁺ diffusion pathways and uniform stress distribution during lithiation. However, the complex preparation process, high cost, and side reactions triggered by the large specific surface area limit its application. Herein, a one-step method is developed to synthesize 2D Si nanosheets from the abundant layered silicate mineral montmorillonite (MMT), via a salt-assisted magnesiothermic reduction. Then, through spray granulation and high-temperature pyrolysis, a high-sphericity Si/C composite (C-SiNS) is finally prepared. The internal structure of C-SiNS consists of stacked Si nanosheets with a carbon shell formed by PVP on the surface. The customized structure promotes a high Li⁺ diffusion rate, effectively alleviates volume expansion, and minimizes side reactions. Benefiting from the robust structural design, C-SiNS demonstrates excellent rate performance (509.78 mAh·g^-1 at a rate of 20 A·g^-1) and outstanding long-term cycling stability (606.80 mAh·g^-1 after 500 cycles at 2 A·g^-1). The feasibility of its practical application is validated through lithium-ion full batteries assembled with commercial LiFePO₄ cathodes (106 mAh·g^-1 after 250 cycles at 0.2 C). The work presents an efficient synthesis strategy for high-rate anode materials and also provides high-value utilization potential options of MMT.