Heteroepitaxial growth of ZnO nanosheet bands on ZnCo₂O₄ submicron rods toward high-performance Li ion battery electrodes

We report the direct synthesis of ZnCo₂O₄ and ZnO/ZnCo₂O₄ submicron rod arrays grown on Ni foil current collectors via an ammonia-evaporation-induced method by controlling the ratio of Zn to Co. These three-dimensional (3D) hierarchical self-supported nanostructures are composed of one-dimensional (1D) ZnCo₂O₄ rods and two-dimensional (2D) ZnO nanosheet bands perpendicular to the axis of the each ZnCo₂O₄ rod. We carefully deal with the heteroepitaxial growth mechanisms of hexagonal ZnO nanosheets from a crystallographic point of view. Furthermore, we demonstrate the ability of these high-surface-area ZnO/ZnCo₂O₄ heterostructured rods to enable improved electrolyte permeability and Li ion transfer, thereby enhancing their Li storage capability (∼900 mA·h·g^-1 at a rate of 45 mA·h·g^-1) for Li ion battery electrodes. [Figure not available: see fulltext.]