High surface area C/SiO2 composites from rice husks as a high-performance anode for lithium ion batteries

Abstract

Micro-sized porous C/SiO2 composites were prepared from rice husks through a facile carbonization process using ZnCl2 as activating agent under Ar atmosphere. The effect of the samples' specific surface area on their electrochemical performance was also studied carefully in this work. The resulting C/SiO2 composite shows mesoporous irregular particle morphology with a high specific surface area of 1191.30m2g−1 under the optimized carbonization temperature. When tested as anode material for lithium ion batteries, this porous C/SiO2 composite exhibits high discharge specific capacity (ca. 1105mAhg−1 at 0.1Ag−1), excellent cycling stability and good rate-capability. The porous structure could buffer the volume change and mechanical strains and shorten lithium-ion diffusion path length. The homogeneous carbon coated layer not only provides good electronic conductivity of the C/SiO2 composite but also further restrains the volume expansion. These characteristics have assured the superior electrochemical performance of the C/SiO2 electrode. The facile and low-cost of this C/SiO2 composite anode material may have great potential to be one alternative for traditional graphite anode.