Three-component Si/C composite materials were synthesized by embedding silicon nanopowder (20 wt.%) and synthetic or expanded graphite micropowder (20-70 wt.%) in a pitch coke matrix. The dispersion of silicon nanoparticles (< 100 nm) and graphite within the carbon matrix and the structural/textural properties of the composites were monitored using optical microscopy, X-ray diffraction and CO_2 adsorption. The electrochemical lithium storage was estimated from galvanostatic charge-discharge characteristics using a composite/lithium half-cell. The incorporation of powdered synthetic graphite into the Si/pitch-coke composite improves the electrochemical performance. The electrode with the three-component composite presents a higher reversible capacity and lower ohmic drop. However, the cycleability of these materials at standard charge/discharge conditions is unsatisfactory. It is demonstrated that adjusting the potential window can be an effective way to improve the cycleability of this kind of composites.
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