In-situ low-temperature strategy from waste sugarcane leaves towards micro/meso-porous carbon network embedded nano Si-SiOx@C boosting high performances for lithium-ion batteries

In light of the silicon-reservoir feature of renewable natural resources, the exploitation of the inexpensive biomass towards high value-added silicon-based materials has achieved great attention. However, the biomass-derived silicon is usually extracted by high-temperature metal-reduction, which tends to trigger side reaction and collapse the porous structure. Herein, introducing molten-salt assisted low-temperature aluminothermic reaction, we have fabricated micro/meso-porous carbon network embedded nano Si-SiOx@C (Si-SiOx@C/C) composites directly using sugarcane leaves as silica and carbon sources. This low-temperature synthesis strategy can perfectly preserve the three-dimensional (3D) carbon network embedded by fine Si-SiOx@C nanoparticles, which is beneficial to enhancing the electrochemical conductivity, reducing volume change, and stabilizing solid electrolyte interface membranes. In addition, the content of Si in SiOx can be controlled by the reduction temperature and reaction time. Consequently, the optimized SC-250-16 anode establishes a favorable reversible capacity (1562.8 mAh g−1 after 400 cycles at 200 mA g−1) and superior cyclability at high rates (678.6 mAh g−1 after 3000 cycles at 2 A g−1). Furthermore, the SC-250-16//LiFePO4 full cell delivers a prominent energy density of 412.1 Wh kg−1. This molten-salt assisted low-temperature reaction strategy can boost the advancement of 3D porous Si/C anodes and their relevant functional composites derived from other biomasses.