Ordered two-dimensional porous Co₃O₄ nanosheets as electrocatalysts for rechargeable Li-O₂ batteries

Lithium-oxygen batteries have attracted considerable interest in the past a few years, because they have higher theoretical specific energy than Li-ion batteries. However, the available energy densities of the Li-O₂ batteries are much less than expected. It is particularly urgent to find catalyst with high activity. Herein, a series of Co₃O₄ with different morphologies (ordered two-dimensional porous nanosheets, flowerlike and cuboidlike) were successfully prepared through facile hydrothermal and calcination methods. Ordered two-dimensional Co₃O₄ nanosheets show the best cycling stability. Detailed experimental results reveal that the superiority of the unique two-dimensional uniform porous structures is vital for Li-O₂ batteries cathode catalysts. Due to the ordered structures with high surface areas and active sites, the catalysts indicate a high specific discharge capacity of about 10, 417 mAh/g at a current density of 200 mA/g, and steadily cycle for more than 50 times with a limited capacity of 1, 000 mAh/g.