Facile preparation of graphene nanosheets encapsulated Fe3O4 octahedra composite and its high lithium storage performances

•Fe3O4 octahedra were made by one step dealloying from FeAl precursor alloy.•Fe3O4@G was made by enwrapping the graphene oxide followed by chemical reduction.•Fe3O4@G shows superior reversible capacity and cycling stability than pure Fe3O4.•Fe3O4@G shows high rate capability at 352.8 mA h g−1 at the rate of 2000 mA g−1.

Graphene nanosheets encapsulated Fe3O4 octahedra were easily fabricated by dealloying method followed by a chemical reduction process in mild conditions. Selectively leaching Al atoms from the FeAl alloy, the Fe atoms undergo natural oxidation and aggregation to generate Fe3O4 octahedra with the main edge length around 500 nm. During the preparation process, graphene oxide (GO) nanosheets served as the structural platform to enwrap the positively charged Fe3O4 octahedra on the basis of the electrostatic assembly followed by the chemical reduction of GO nanosheets. Benefitting from the combination of well encapsulated graphene nanosheets with Fe3O4 octahedra, the as-made composite exhibited dramatically enhanced lithium storage performances with superior reversible capacity, remarkable rate capability, and unique cycling stabilities compared with the pure Fe3O4. Especially, the reversible capacity remains as high as 724.7 and 523.2 mA h g−1 at the current densities of 300 and 1000 mA g−1, respectively, after long term testing for 200 and 300 cycles. The Fe3O4@G composite possesses unique lithium storage performance with the advantages of facile and large scale preparation.

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