Improved cycle stability of Fe-air solid state oxide rechargeable battery using LaGaO3-based oxide ion conductor

The effect of operating temperature on the discharge potential and cycle stability of an Fe-air solid oxide rechargeable battery was studied. An Fe-air cell operated at 773 K exhibited the highest discharge potential (1.07 V) and high cycle stability with a current density of 5 mA cm−2. The high discharge potential at lower operating temperatures is due to aggregation of the anode and Fe powder being suppressed. The high redox cycle stability of the Ni-Fe-based anode at 773 K is explained by the small volume change with suppressed aggregation under low-temperature operation. Electrochemical charge-discharge measurements at 773 K revealed excellent cycle stability for 30 cycles with a high energy density (round trip efficiency >80%).