Si/graphene composite prepared by magnesium thermal reduction of SiO2 as anode material for lithium-ion batteries

•A nano-sized Si/graphene composite was prepared by magnesium thermal reducing of the in-situ generated SiO2 on graphene sheets.•The Si/graphene composite delivers large reversible capacity with excellent cycling stability.•The graphene and nanospaces between Si nanoparticles could accommodate volume expansion during lithium insertion and extraction.

A nanosized Si/graphene composite was prepared by magnesium thermal reduction of the in-situ generated SiO2 particles on graphene sheets, in which about 5 nm-silicon nanoparticles were homogeneously loaded on graphene sheets. The unique structure can not only accommodate the large volume changes, but also maintain electronic conductivity during Li-ion insertion/extraction. The composite delivers an initial reversible capacity of 1750 mAh/g at a current rate of 100 mA/g and exhibits an excellent cycling stability with a capacity of 1374 mAh/g over 120 cycles.