Facile synthesis of Fe3O4@C quantum dots/graphene nanocomposite with enhanced lithium-storage performance

• Carbon-coated Fe3O4 quantum dots/graphene composite was prepared via a facile approach.
• Carbon-coated Fe3O4 quantum dots around 7–10 nm are distributed uniformly on graphene.
• The nanocomposite delivers a reversible capacity of 940 mA h/g after 100 cycles.
• The nanocomposite shows an improved lithium-storage performance with high cycling stability and rate capacity.

Carbon-coated Fe3O4 quantum dots/graphene composite was prepared via a hydrothermal and calcining process. XRD and TEM analysis revealed that carbon-coated Fe3O4 quantum dots with a size around 7–10 nm were distributed uniformly on graphene nanosheets. The carbon shell can preserve structural stabilization of Fe3O4 nanoparticles by preventing the aggregation and buffering the volume expansion during charge/discharge processes. In addition, the graphene nanosheets formed a three-dimensional network for the transportation of Li+ ions and electrons. When evaluated as anode material for lithium-ion batteries, the nanocomposite showed an improved lithium-storage performance with high cycling stability and good rate capacity. Furthermore, it exhibited an initial discharge capacity of 1300 mA h/g and retained a reversible capacity of about 940 mA h/g after 100 cycles at a current density of 150 mA/g.

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