Silicon/carbon and silicon/carbon/graphite composites have been synthesized at room temperature using concentrated H2SO4 as a dehydration agent. As a ductile matrix, the novel amorphous carbon obtained from the dehydration process could effectively buffer the volume change of silicon particles during discharge-charge cycling. The introduction of graphite in the silicon/carbon composite further improved the cycling performance. The composite with 30 wt % of amorphous carbon replaced by graphite demonstrated a stable capacity of 712.8 mAh g(-1) and a high capacity retention ratio of 84.1% at 0.1 C over 50 cycles, suggesting it is a favorable candidate as anode material for lithium-ion batteries. (c) 2006 The Electrochemical Society.