Conformal Coating of Heterogeneous CoO/Co Nanocomposites on Carbon Nanotubes as Efficient Bifunctional Electrocatalyst for Li-Air Batteries

The effective design of noble-metal-free electrocatalysts is critical for improving the stability and cyclability of Li-air batteries. In this report, CoO/Co nanoparticles are conformally decorated on the surface of CNTs by a facile chemical bath deposition followed by thermal annealing. In a simulated air environment, Li-air battery with the CNTs@CoO/Co electrocatalyst exhibits a dramatic reduction of charge voltage overpotentials (0.39 V) and good cycling stability (110 cycles) as compared with that made with bare CNTs. The superior electrochemical performances are ascribed to the prior and strong absorption of LiO2 on the surface of CoO/Co, which can alleviate the formation of side-products, then leading to a decreased overpotential. The synergistic effect between CoO/Co and CNTs can also provide more catalytic sites for the ORR/OER, promoting the formation/decomposition reversibility of Li2O2. These results confirm that the CNTs@CoO/Co electrode can be a promising electrocatalyst for Li-air batteries. (C) 2016 Elsevier Ltd. All rights reserved.