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 high-performance 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 Co-Cu LDH nanosheets, possessing an average thickness of 4.3 nm and a high surface area of 163 m² 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⁻¹at 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 CuCo₂O₄electrode. 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 O₂and ions in Li-air battery.