Silicon/graphite nanocomposite electrodes prepared by low pressure chemical vapor deposition

Abstract : Silicon-coated carbon has been prepared by low pressure chemical vapor deposition (LPCVD) using silane as the precursor gas. A porous homogeneous layer made of spherical shaped particles was deposited. The average silicon particle diameter varied from 5 to 30 nm depending upon deposition conditions. Theoretical calculations have been performed to determine the capacity of graphite/silicon electrodes according to the shape of graphite flakes and to the thickness of the silicon layer. This calculation shows that even a minor amount of silicon is efficient in enhancing the capacity of the composite electrode. The electrochemical performance of carbon/silicon composite electrodes has been investigated by charge/discharge galvanostatic tests and cyclic voltammetry experiments. A small amount of silicon (3.6 wt%) leads to an increase of the capacity of the graphite electrode (+27%) without significant impact on the cyclability, thus combining the effect of both materials. Increasing the silicon content (10.7 wt%) leads to an initial capacity of 780 mAh g−1 but it strongly affects the cycling ability of the composite negative electrode.