Lithium Storage Performance of Zinc Ferrite Nanoparticle Synthesized with the Assistance of Triblock Copolymer P123.

Abstract

The ZnFe2O4 samples with the triblock copolymer P123 (P123) additive quantity of 0 wt.%, 2 wt.%, 5 wt.%, 8 wt.% and 10 wt.% were prepared by a very facile homogeneous precipitation method followed by high temperature sintering. The microstructures of the prepared samples were analyzed by X-ray diffraction (XRD) and Field emission scanning electron microscopy (FESEM). The results revealed that the five prepared samples are all normal spinel zinc ferrite (ZnFe2O4); the sample with the P123 additive quantity of 8 wt.% has the smallest particle size among the five samples. The lithium storage performances of the prepared samples are characterized by cyclic voltammograms (CV), electrochemical impedance spectroscopy (EIS), and charge-discharge tests. The results demonstrated that adding proper amount of P123 can obviously improve the lithium storage performances of zinc ferrite spinel powder. But excessive P123 can induce the particle agglomerates so that the lithium storage performance of sample decays significantly. The ZnFe2O4 sample with the P123 additive quantity of 8 wt.% exhibited the highest electrochemical activity, the best rate performance, and superior cycling stability. For example, after 50 charge/discharge cycles under a current density of 120 mA g-1, the ZnFe2O4 sample with the P123 additive quantity of 8 wt.% can retain a specific discharge capacity of 468 mAh g-1, much higher than that of for the ZnFe2O4 sample with the P123 additive quantity of 0 wt.% (224 mAh g-1).