Rice husk derived silicon/carbon and silica/carbon nanocomposites as anodic materials for lithium-ion batteries

The unique hierarchical structures over multiple length scales (micrometer-to-nanometer levels) possessed by the natural biosubstances make them to be ideal substrates for the syntheses of functional nanostructured artificial materials. In this work, nanostructured silicon/carbon and silica/carbon nanocomposites derived from rice husks were obtained, which showed enhanced electrochemical performances as being employed as anodic materials for lithium-ion batteries. The homogeneous silicon/carbon composite was synthesized via a one-pot carbonization/magnesiothermic-reduction process of the rice husk, which was composed of fine silicon nanocrystals embedded in the carbon matrix. As being applied as an anodic material, it delivered a high reversible capacity of 560 mAh g(-1) as cycled at a current density of 100 mA g(-1) over 180 cycles with good structural stability. Direct carbonization of the rice husk resulted in the silica/carbon nanocomposite, and it was found that, as being employed as an anodic material, the higher carbonization temperature led to better electrochemical performances such as the cycling stability (650 mAh g(-1) after 150 cycles at 100 mA g(-1) for the sample carbonized at 900 degrees C) and rate capacity. Silver nanoparticles were further composited with the silicon/carbon and silica/carbon hybrids to make the corresponding ternary nanocomposites, resulting in improved electrochemical performances.