Microsized Porous SiO_<i>x</i>@C Composites Synthesized through Aluminothermic Reduction from Rice Husks and Used as Anode for Lithium-Ion Batteries

Abstract

Microsized porous SiO_x@C composites used as anode for lithium-ion batteries (LIBs) are synthesized from rice husks (RHs) through low-temperature (700 °C) aluminothermic reduction. The resulting SiO_x@C composite shows mesoporous irregular particle morphology with a high specific surface area of 597.06 m²/g under the optimized reduction time. This porous SiO_x@C composite is constructed by SiO_x nanoparticles uniformly dispersed in the C matrix. When tested as anode material for LIBs, it displays considerable specific capacity (1230 mAh/g at a current density of 0.1 A/g) and excellent cyclic stability with capacity fading of less than 0.5% after 200 cycles at 0.8 A/g. The dramatic volume change for the Si anode during lithium-ion (Li⁺) insertion and extraction can be successfully buffered because of the formation of Li₂O and Li₄SiO₄ during initial lithiation process and carbon coating layer on the surface of SiO_x. The porous structure could also mitigate the volume change and mechanical strains and shorten the Li⁺ diffusion path length. These characteristics improve the cyclic stability of the electrode. This low-cost and environment-friendly SiO_x@C composite anode material exhibits great potential as an alternative for traditional graphite anodes.