Electrochemical performance of Al-Si-graphite composite as anode for lithium-ion batteries

Al-Si-graphite composite with low 7.9 wt.% Si was synthesized by ball-milling eutectic Al-Si powder and graphite. Its reversible capacity remained above 0.65 Ah/g after 10 cycles, corresponding to 1.6 Ah/cm3, almost double that of graphite alone. Ex-situ XRD indicates that in Al-graphite the large volume change during lithium insertion/removal causes the active material to become isolated and not available for electrochemical reactions, while in Al-Si-graphite all the material remains available.