Nanodispersed silicon in pregraphitic carbons

Using chemical-vapor deposition nanodispersed silicon has been prepared in carbon at temperatures between 850 and 1050 °C. Samples with up to 11% atomic silicon in carbon show the same pregraphitic x-ray-diffraction pattern as those without silicon. X-ray-absorption spectroscopy shows that the silicon is bonded mostly to carbon neighbors and that large clusters of silicon are not found. It is believed that silicon atoms, or small clusters of a few silicon atoms, are located in regions of ‘‘unorganized carbon’’ which separate small regions of organized graphene layers. These materials may have application as electrode materials in advanced rechargeable lithium batteries.