Hierarchical porous cobalt oxide array films prepared by electrodeposition through polystyrene sphere template and their applications for lithium ion batteries

Hierarchical porous cobalt oxide (Co3O4) array films are successfully prepared by electrodeposition through polystyrene sphere monolayer template. The as-prepared Co3O4 array films exhibit three typical porous structures from non-close-packed bowl array to close-packed bowl array and hierarchical two layer array structures. These Co3O4 array films have a hierarchical porous structure, in which the skeleton is composed of ordered arrays possessing nanoporous walls. A possible growth mechanism of porous Co3O4 array films is proposed. As anodes for Li ion batteries, the as-prepared Co3O4 array films exhibit quite good cycle life and high capacity. The first discharge capacity for the three Co3O4 array films is 1511, 1475, 1463 mAh g−1, respectively, and their initial coulombic efficiencies are as high as 72%. The specific capacity after 50 cycles for the three electrodes is 712, 665 and 640 mAh g−1 at 1C rate, corresponding to 80%, 75%, 72% of the theoretical value (890 mAh g−1), respectively.