An ultra stable and efficient bifunctional cathode catalyst for iron molten air batteries

Iron molten air battery possesses cost-efficiency and high theoretical specific energy density merits, and is one of the promising battery systems for future application in energy storage. Although substantial efforts and significant progress have been made in recent years, it is still one of the major challenges to explore a stable and efficient bifunctional catalyst in high-temperature molten salt environments. Herein, the NiMnO3–La2O3 composite is synthesized on porous nickel foam substrates by a hydrothermal method and used as a cathode catalyst for the iron molten air battery. The results show that the NiMnO3–La2O3 composite has excellent stability and durability. After 250 cycles in a 500 °C molten salt electrolyte, the microscopic morphology of the catalyst is almost the same as that before using. Moreover, the NiMnO3–La2O3 composite exhibits excellent oxygen evolution reaction (OER)/oxygen reduction reaction (ORR) activity, less discharge polarization, and excellent rate performance. The iron molten air battery with NiMnO3–La2O3 composite cycles stably over 250 cycles with the highest Coulombic efficiency of 99.8% and the average discharge potential of 1.14 V at 500 °C in the air. This work opens a new avenue toward developing a stable and efficient bifunctional cathode catalyst for the iron molten air batteries.