Hydrothermal-synthesized NiO nanowall array for lithium ion batteries

We report a self-supported NiO nanowall array prepared by a facile hydrothermal synthesis method. The microstructure and morphology of the sample are characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The hydrothermal-synthesized NiO nanowalls with thicknesses of similar to 20 nm arrange vertically to the substrate forming a net-like nanowall array structure. As anode material for lithium ion batteries, the NiO nanowall array exhibits better electrochemical performances with higher coulombic efficiency and better cycling performance as compared to the dense NiO film. The NiO nanowall array shows an initial coulombic efficiency of 76%, as well as good cycling stability with a capacity of 567 mAh g (1) at 0.3 A g (1) after 50 cycles, higher than those of the dense polycrystalline NiO film (361 mAh g (1)). The superior electrochemical performance is mainly due to the unique nanowall array structure with shorter diffusion length for mass and charge transport. (C) 2012 Elsevier B. V. All rights reserved.