Iron–Air Battery Operating at High Temperature

Abstract A simple configuration for an Fe–air rechargeable battery operating at high temperature was investigated. Two different ceramic electrolytes, that is, gadolinia‐doped ceria (CGO) and strontium/magnesium‐doped lanthanum gallate (LSGM), were studied. Strontium‐doped lanthanum ferrite‐cobaltite (LSFCO) perovskite was used as the air electrode, whereas an Fe 0 /Fe 2 O 3 –CGO composite was used as the Fe electrode. The synthesized CGO and LSGM supporting electrolytes were characterized by proper ionic conductivity for this application (7.4×10 −2 S cm −1 at 800 °C). The LSFCO perovskite electrode showed excellent reversibility in symmetrical cells. Low overpotentials were recorded for the evolution of oxygen (0.1 V at 1.7 A cm −2 ) and the oxygen reduction process (0.1 V at 2.4 A cm −2 ) at 800 °C. The high‐temperature battery based on the CGO electrolyte showed a pronounced propensity to spontaneously discharge. This was caused by redox behavior involving the interconversion between the Ce 4+ and Ce 3+ ions in the crystallographic structure, which caused a parasitic electron drag through the electrolyte. On the other hand, the LSGM‐based battery showed promising cyclability characteristics at 800 °C with an open‐circuit voltage higher than 1 V, an electric capacity of 0.3 Ah g −1 , and an energy density of 0.22 Wh g −1 . However, significant improvements in the coulombic efficiency (≈42 %) for this battery system are necessary for practical applications.