Cobalt-Doped Perovskite-Type Oxide LaMnO₃ as Bifunctional Oxygen Catalysts for Hybrid Lithium-Oxygen Batteries

Perovskite-type oxides based on rare-earth metals containing lanthanum manganate are promising catalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in alkaline electrolyte. Perovskite-type LaMnO₃ shows excellent ORR performance, but poor OER activity. To improve the OER performance of LaMnO₃ , the element cobalt is doped into perovskite-type LaMnO₃ through a sol-gel method followed by a calcination process. To assess electrocatalytic activities for the ORR and OER, a series of LaMn_1-x Co_x O₃ (x=0, 0.05, 0.1, 0.2, 0.3, 0.4, and 0.5) perovskite oxides were synthesized. The results indicate that the amount of doped cobalt has a significant effect on the catalytic performance of LaMn_1-x Co_x O₃ . If x=0.3, LaMn_0.7 Co_0.3 O₃ not only shows a tolerable electrocatalytic activity for the ORR, but also exhibits a great improvement (>200 mV) on the catalytic activity for the OER; this indicates that the doping of cobalt is an effective approach to improve the OER performance of LaMnO₃ . Furthermore, the results demonstrate that LaMn_0.7 Co_0.3 O₃ is a promising cost-effective bifunctional catalyst with high performance in the ORR and OER for application in hybrid Li-O₂ batteries.