Si/MgO composite anodes for Li-ion batteries

A Si/MgO composite anode material was prepared by a simple magnesium reduction process using silicon oxide and magnesium as starting reactants. The feasibility of this process is discussed from the thermodynamic viewpoint. The resultant composite material is mainly composed of Si and MgO components. MgO, acting as a buffer layer, can accommodate the large volume change of active Si during the charge/discharge process, thus the cycling stability is improved. Electrochemical tests demonstrate that the first charge and discharge capacities of the synthesized Si/MgO composite anode are ca. 1380 and 1046 mAh.g(-1), respectively, with an initial coulomb efficiency of ca. 76%. The magnesium reduction process provides a novel idea for the synthesis of Si-based anode materials.