Co-substituted Nonstoichiometric LaMn1–xCoxO3+δ Perovskite Oxide Cathode Catalysts for the Oxygen Reduction Reaction for High-Performance Zn–Air Batteries

Zn–air batteries (ZABs) are highly promising energy conversion devices primarily because of their high energy densities and environmental friendliness. In such devices, the efficiency and stability of the catalyst for the oxygen reduction reaction (ORR) at the cathode have a significant effect on battery performance. Therefore, in this study, we investigated the ORR catalytic activities of a series of Co-substituted nonstoichiometric LaMn1–xCoxO3+δ perovskite oxides and explored their potential as cathode catalysts for ZABs. We found that the amount of Co did not change the valence states of La, Mn, and Co but decreased the number of cation vacancies. Further, the LaMn0.8Co0.2O3+δ sample, which had the shortest Mn–O bond length (that is, the strongest Mn–O interaction), exhibited the highest catalytic ORR activity. Further, a ZAB assembled with the LaMn0.8Co0.2O3+δ catalyst as the cathode material demonstrated a comparable power density, much higher energy density, and better cycling stability to that of a ZAB containing a commercial Pt/C catalyst. Overall, these findings provide valuable insights with regard to the Mn–O bond length and methods for enhancing the catalytic ORR activity of Mn-based perovskites and will aid the development of more efficient and sustainable cathode catalysts for ZABs.