Microsized Porous SiOx@C Composites Synthesized through Aluminothermic Reduction from Rice Husks and Used as Anode for Lithium-Ion Batteries

Microsized porous SiOx@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 SiOx@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 SiOx@C composite is constructed by SiOx 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 SiOx. 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 SiOx@C composite anode material exhibits great potential as an alternative for traditional graphite anodes.