What do we need for the lithium-air batteries: A promoter or a catalyst?

LaSr-based perovskite materials are frequently studied as catalyst at the cathode of the lithium-air batteries (LAB). In this study, we compared Pb, Ba and Sr in the form of La0.65X0.35MnO3 (X = Pb, Ba, Sr) at the cathode of LAB in terms of total discharge capacity, cell cycling and discharge reaction products. The electrochemical characterization was carried out at the discharge current density of 200 mA g−1 under dry oxygen atmosphere. The cell with La0.65Pb0.35MnO3, La0.65Ba0.35MnO3, La0.65Sr0.35MnO3 and Acetylene black carbon (alone) displayed capacity values of 7211 mAh g−1, 6205 mAh g−1, 6760 mAh g−1 and 5925 mAh g−1, respectively. The number of cycle and the operation time with the cells using La0.65Pb0.35MnO3, La0.65Ba0.35MnO3, La0.65Sr0.35MnO3 and Acetylene black carbon (alone) at 0.1 mA cm−2 were 35 (650 h), 18 (300 h), 20 (76 h) and 11 (64 h), respectively. The cells with La0.65Pb0.35MnO3 showed columbic efficiencies ranging from 95 to 97% with superior performance compared to La0.65Ba0.35MnO3 and La0.65Sr0.35MnO3 with columbic efficiency of about 87%. The overpotential value was decreased approximately 300 mV by the use of La0.65Sr0.35MnO3 as a catalyst, whereas no change in the overpotential value was observed by the use of La0.65Ba0.35MnO3 and La0.65Pb0.35MnO3 as a promoter.