Perovskite LaCoxMn1-xO3-σ with Tunable Defect and Surface Structures as Cathode Catalysts for Li-O2 Batteries.

Rechargeable lithium-oxygen batteries have shown great potential as next-generation sustainable and green energy storage systems. The bifunctional catalyst plays an important role in accelerating the cathode kinetics for practical realization of the batteries. Herein, we employ the surface structure and defect engineering to introduce surface-roughened nanolayers and oxygen vacancies on the mesoporous hollow LaCoxMn1-xO3-σ perovskite catalyst by in situ cation substitution. The experimental results show that the O2-electrode with the LaCo0.75Mn0.25O3-σ catalyst exhibits an extremely high discharge capacity of 10,301 mA h g-1 at 200 mA g-1 for the initial cycle and superior cycling stability under a capacity limit of 500 mA h g-1 together with a low voltage gap of 1.12 V. Good electrochemical performance of LaCo0.75Mn0.25O3-σ can be attributed to the synergistic effect of the hierarchical mesoporous hollow structure and the abundant oxygen vacancies all over the catalyst surface. We reveal that the modified surface structure can provide more accessibility of active sites to promote electrochemical reactions, and the introduced oxygen vacancy can serve as an efficient substrate for binding intermediate products and decomposition reactions of Li2O2 during discharge and charge processes. Our methodology provides meaningful insights into the rational design of highly active perovskite catalysts in energy storage/conversion systems.