Zn-Fe-O@C hollow microspheres as a high performance anode material for lithium-ion batteries

In this study, Zn-Fe-O@C hollow microspheres are prepared by chemical vapor deposition (CVD) method with ZnFe2O4 hollow microspheres as precursors which are synthesized via a facile solvothermal method. ZnFe2O4 hollow microspheres and Zn-Fe-O@C hollow microspheres are characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy. The physical analysis shows a fraction of Fe(III) reduced to Fe(II) and the hollow microspheres maintained during the CVD process. Zn-Fe-O@C hollow microspheres can deliver a reversible specific capacity of 1035.6 mA h g(-1) after 50 cycles at a current density of 100 mA g(-1), and maintain a stable capacity as high as 1000 mA h g(-1) at 500 mA g(-1) after 200 cycles. Compared with ZnFe2O4 hollow microspheres, Zn-Fe-O@C hollow microspheres present excellent rate performance. The better electrochemical performances of the Zn-Fe-O@C hollow microspheres should be ascribed to the carbon coating, which can elevate electrical conductivity and improve the structural stability of the active materials.