Cobalt-copper layered double hydroxide nanosheets as high performance bifunctional catalysts for rechargeable lithium-air batteries

Designing novel cost-effective catalysts is one of the greatest challenges in the development of highperformance rechargeable Li-air battery. Here, we report the synthesis of novel cobalt-copper layered double hydroxide (LDH) nanosheets via a simple co-precipitation method under Ar gas. The resulting CoCu LDH nanosheets, possessing an average thickness of 4.3 nm and a high surface area of 163 m(2) g(-1), have been applied as bifunctional catalysts for Li-air battery. In the simulated air environment, Li-air batteries with Co-Cu LDH nanosheets demonstrate higher discharge capacity of 4870 mAh g(-1) at 200 mA g(-1), lower charge overpotential and better cycling stability with controlling capacity of 1000 mAh g(-1), which is much better than that with CuCo2O4 electrode. The enhanced electrochemical performance is ascribed to the large interface between electrolytes and catalysts resulting from high surface area of Co-Cu LDH, providing plenty of actives sites to promote the formation/decomposition of Li2O2. The unique ultrathin nanosheet structure of Co-Cu LDH can also facilitate the mass transportation of O-2 and ions in Li-air battery. (C) 2016 Elsevier B.V. All rights reserved.