Formation of carbon-coated ZnFe2O4 nanowires and their highly reversible lithium storage properties

Abstract

In this paper, carbon-decorated ZnFe₂O₄ nanowires, having one-dimensional geometry with diameters of 70–150 nm and lengths of several micrometers, were prepared and used as a highly reversible lithium ion anode material. They can be obtained from calcination of glucose-coated ZnFe₂(C₂O₄)₃ nanowires, which were prepared in glucose containing microemulsion solutions. The physicochemical properties of carbon-coated ZnFe₂O₄ nanowires were investigated by scanning electron microscopy, X-ray diffraction, Raman spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The carbon-coated ZnFe₂O₄ nanowires showed a substantially increased discharge capacity of ca. 1285.1 mA h g⁻¹ at the first cycle as compared with non-carbon-coated ZnFe₂O₄ nanowires (ca. 1024.3 mA h g⁻¹) and ZnFe₂O₄ nanoparticles (ca. 1148.7 mA h g⁻¹). Moreover, the discharge capacity of the carbon-coated ZnFe₂O₄ nanowires was maintained with no degradation even after 100 charge/discharge cycles. The high cycling durability, rate capability, and coulombic efficiency suggest that the carbon-coated ZnFe₂O₄ nanowires prepared here can be promising anode candidates for a highly reversible lithium storage electrode.