Quenching-induced construction of graphene-wrapped Fe3O4 composite as ultrahigh-performance Li-storage electrode

Iron oxide/graphene hybrids are outstanding electrodes with high specific capacity for secondary batteries. However, in practice there still remains challenges in alleviating the poor electrical conductivity and significant volume changes of FeOx during the lithiation/delithiation process. Herein, we describe the discovery of fabricating graphene-wrapped Fe3O4 (3D-rGO/Fe3O4) via a solution-based self-assembly process. During which, GO/Fe3O4/Na2SO4 precursor was first formed by the corrosion reaction of metallic Fe in GO aqueous solution and antisolvent self-assembly, which was then quenched into water to dissolve the Na2SO4 template and meanwhile enable the GO to shrink and encapsulate the Fe3O4 nanoparticles spontaneously, followed by a final thermal reduction. Fe3O4 nanoparticles, with a diameter of tens of nanometers, are homogeneously enwrapped into rGO framework, guaranteeing the “plane-to-plane” interconnection. The obtained 3D-rGO/Fe3O4 demonstrates unprecedented Li-storage behaviors when utilized as Li-ion battery anode. Furthermore, quantitative kinetic analysis revealed that both capacitance and diffusion mechanisms account for Li-storage behavior. This contribution not only presents a ultrahigh-performance Li-storage electrode but also shows a novel methodology to design and construct other graghene-based metallic compounds for various applications.