Fabrication of free-standing ZnMn2O4 mesoscale tubular arrays for lithium-ion anodes with highly reversible lithium storage properties.

In this paper, ZnMn2O4 mesoscale tubular arrays on current collectors were successfully synthesized using a reactive template route combined with a postcalcination process through the shape-preserving conversion of ZnO nanorod arrays in aqueous solutions at room temperature. On the basis of the experimental analyses, including X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy, a plausible formation mechanism of ZnMn2O4 tubular arrays was proposed in which solid ZnO nanorods are gradually transformed to ZnMn2O4 tubules via a simple cation exchange process between Zn(2+) and Mn(2+), followed by a postannealing process. Moreover, the lithium storage properties of the as-prepared ZnMn2O4 tubular structures were investigated by applying the structures as an active electrode material without auxiliary additives. The ZnMn2O4 array electrodes showed an excellent discharge capacity of ca. 1198.3 mAh g(-1) on the first cycle and exhibited outstanding cycling durability, rate capability, and Coulombic efficiency. These results indicate that the free-standing tubular array architectures of ZnMn2O4 prepared directly on the current collector can be powerful candidates for a highly reversible lithium storage electrode platform.