The study of Mg2Si/carbon composites as anode materials for lithium ion batteries

The study of Mg₂Si/C composites as anode materials for lithium ion batteries is reported in this paper. Firstly, Mg₂Si was synthesized by mechanically activated annealing (MAA) technique and the preparing conditions for pure Mg₂Si alloy were investigated and optimized. Then the composite materials of Mg₂Si and carbon materials such as CNTs and CMS with different ratios were prepared by the followed ball-milling techniques. Their electrochemical performances were compared by the galvanostatically charge/discharge and EIS experiments. The pure Mg₂Si alloy delivers a large initial capacity, but the capacity decreases rapidly with cycling. In contrast, the composites show good cyclic stability and deliver a reversible capacity of about 400 mAh g⁻¹ with 40% carbon in the composite. The results of EIS indicate that the composite of Mg₂Si/CMS has better interface stability than that of pure Mg₂Si materials.