Facile and large-scale fabrication of hierarchical ZnFe2O4/graphene hybrid films as advanced binder-free anodes for lithium-ion batteries†
Hierarchical ZnFe2O4/graphene (ZFO/GN) hybrid films have been successfully fabricated by a facile one-step cathodic electrophoretic deposition (EPD) of graphene oxide, Fe(NO3)3, and Zn(NO3)2 colloidal suspension on copper foils and subsequent thermal annealing. The obtained ZnFe2O4 nanoparticles are homogeneously dispersed and anchored between the graphene sheets, forming a unique sheet-like hybrid nanostructure. It was found that different ZnFe2O4 morphologies and their mass content in the hybrid films could be easily controlled by varying the concentration of the precursor. The resulting binder-free ZFO/GN hybrid films were directly evaluated as anodes for rechargeable lithium half-cells without adding any polymer binder or conductive additives. Among these, the ZFO/GN hybrid film with 55.88 wt% graphene exhibits superior lithium storage performance with a high specific reversible capacity (910.21 mA h g−1 at a high current density of 200 mA g−1), excellent rate capability (more than 510 mA h g−1 even at the specific current of 3200 mA g−1), and good electrochemical cyclic stability (stable at ∼881 mA h g−1 after 200 cycles).