Yolk-shell porous Fe3O4@C anchored on graphene as anode for Li-ion half/full batteries with high rate capability and long cycle life

Iron oxides have been widely studied as anode materials for lithium-ion batteries (LIBs) due to their high conductivity (5 × 104 S m-1) and high capacity (ca. 926 mAh g-1). However, having a large volume change and being highly prone to dissolution/aggregation during charge/discharge cycles hinder their practical application. Herein, we report a design strategy for constructing yolk-shell porous Fe3O4@C anchored on graphene nanosheets (Y-S-P-Fe3O4/GNs@C). This particular structure can not only introduce sufficient internal void space to accommodate the volume change of Fe3O4 but also afford a carbon shell to restrict Fe3O4 overexpansion, thus greatly improving capacity retention. In addition, the pores in Fe3O4 can effectively promote ion transport, and the carbon shell anchored on graphene nanosheets is capable of enhancing overall conductivity. Consequently, Y-S-P-Fe3O4/GNs@C features a high reversible capacity of 1143 mAh g-1, an excellent rate capacity (358 mAh g-1 at 10.0 A g-1), and a prolonged cycle life with robust cycling stability (579 mAh g-1 remaining after 1800 cycles at 2.0 A g-1) when assembled into LIBs. The assembled Y-S-P-Fe3O4/GNs@C//LiFePO4 full-cell delivers a high energy density of 341.0 Wh kg-1 at 37.9 W kg-1. The Y-S-P-Fe3O4/GNs@C is proved to be an efficient Fe3O4-based anode material for LIBs.