Enhanced capacity for lithium–air batteries using LaFe0.5Mn0.5O3–CeO2 composite catalyst

LaFe0.5Mn0.5O3 and Ce-incorporated LaFe0.5Mn0.5O3 catalysts for Li–air batteries were synthesized by co-precipitation (CP) and micro-emulsion methods with the increasing Ce/(La+Ce) ratios from 0 to 0.5. Ce has a low solubility in LaFe0.5Mn0.5O3 perovskite lattices. Instead of forming single-phase La1−xCexFe0.5Mn0.5O3 perovskite, a multi-phase LaFe0.5Mn0.5O3–CeO2 composite was obtained even for Ce/(La+Ce) = 0.05. Such catalysts were used in the cathode of Li–air batteries and the discharge test showed that LaFe0.5Mn0.5O3–CeO2 composite catalyst can effectively improve the specific capacity with the highest capacity of ~4700 mAh/g for Ce/(La+Ce) = 0.05 (by CP). There is also a 0.05 V increase in discharge voltage compared with the reference cell without catalyst, with the discharge voltage plateau at ~2.75 V. The overall ranking in terms of capacity was Ce/(La+Ce) = 0.05 > Ce/(La+Ce) = 0.1 > Ce/(La+Ce) = 0.5 > Ce/(La+Ce) = 0. The capacity increase for Ce/(La+Ce) = 0.05 and 0.1 samples is attributed to the enhanced oxygen storage/release capability and the increased conductivity with the incorporation of CeO2.