Corncob-shaped ZnFe2O4/C nanostructures for improved anode rate and cycle performance in lithium-ion batteries

Abstract

Novel corncob-shaped ZnFe₂O₄/C nanostructured composite materials have been successfully synthesized through a facile co-precipitation method with carbamide as carbonaceous matrix. The morphology and structure of the samples were characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and transition electron microscopy (TEM), and the physical and electrochemical properties were tested by thermogravimetry and an electrochemical system. The corncob-shaped ZnFe₂O₄/C nanostructured anode materials exhibit outstanding cycling performance and rate capability in comparison with pure ZnFe₂O₄ anode materials. Electrochemical results show that the corncob-shaped ZnFe₂O₄/C nanocomposite materials exhibit an initial discharge capacity of approximately 1591.6 mA h g⁻¹ with an initial coulombic efficiency of 80.4% at a constant density of 100 mA g⁻¹. A reversible discharge capacity of 1119.1 mA h g⁻¹ is still obtained after 100 cycles. The discharge capacities can still be as high as 889 mA h g⁻¹ at a high rate of 4 C (1 C = 250 mA g⁻¹). The excellent electrochemical performances are probably ascribed to the multiple synergetic factors that stem from their uniform nanoparticle size, complete crystallization with corncob shape, and organic pyrolysis of carbon inlaid in the corncob shaped nanostructure. The corncob-shaped ZnFe₂O₄/C nanocomposite will be a promising anode material for advanced lithium ion batteries.