In recent years, lithium ion battery has been widely used on portable electronic devices and electric/hybrid vehicles because of its high energy density and cycling stability. As an anode material for the lithium ion battery, Silicon(Si) is getting attention for its high theoretical specific capacity (about 4200mAh/g) and its proper potential range for lithium insertion and extraction. However, Si has properties that could be obstacles for its practical use as the lithium ion battery anode. Si not only has low intrinsic electric conductivity but also undergoes severe volume changes during the lithium ion insertion/extraction process which results in pulverization of the electrode materials, causing the capacity to fade. To overcome these problems and enhance the electric conductivity, we synthesized Silicon/Carbon composites as an anode material. Si/C composites were prepared by two step method, including magnesiothermic reduction of SBA-15(Santa Barbara Amorphous material No. 15) and carbonization of phenol resin. The electrochemical performances of Si/Carbon composites were investigated to find the effect of binders and an electrolyte additives by charge/discharge, cyclic voltammetry and impedance tests. The anode electrode of Si/C composite with PAA binder appeared better capacity(1,899 mAh/g) and the capacity retention ratio(92%) than that of other composition coin cells during 40 cycles. Also, Vinylene carbonate(VC) was tested as an electrolyte additive. The influence of this additive on the behavior of Si/Carbon anodes was very positive(3,049 mAh/g), since the VC additive is formed passivation films on Si/C surfaces and suppresses irreversible changes in electrolyte solution .