Fe-Air battery operating at 700 °C: a case study

The aim of this work is the evaluation of a Fe-air battery cell for application as electric energy storage device. Zhao et al. suggested an architecture similar to a reversible SOFC/SOEC cell combined with an active Fe-electrode placed in the same closed fuel electrode chamber [1]. The operation of such cell consisted in a combination of a reversible SOFC/SOEC cell with the redox cycle of Fe-Fe2O3 and requires a recirculation of H2/H2O. The net electromotive force is given by the Fe-redox couple. Although they achieved good performance, such architecture is affected by cells stacking constraints. In this work we explored the feasibility of a simply architecture consisted of a sandwich based on Fe2O3-CGO as Fe electrode, La0.8Sr0.2Ga0.8Mg0.2O3 (LSGM) or Gd0.1Ce0.9O2 as supporting electrolyte and La0.6Sr0.4Fe0.8Co0.2O3 (LSFCO) as O2 electrode. Such cells had an architecture similar to a SOFC cell. However, such cells did not require any gas recirculation, whereas no internal manifold of gas is expected in a stack of these cells. The cell battery based on CGO showed a significant propensity to the spontaneous discharge due to low electrical stability of the Ce(IV) and due to its large capability for the oxygen storage. On the other hand, LSGM based cell battery showed stable current capacity (0.3 Ah g-1), energy density (0.22 Wh g-1), and voltage efficiency (67%).