High performance La0.3Ca0.7Cr0.3Fe0.7O3−δ air electrode for reversible solid oxide fuel cell applications

Abstract

A novel mixed-conducting perovskite oxide (La0.3Ca0.7Fe0.7Cr0.3O3−δ, LCFCr), prepared using the combustion method, has been developed as a new air electrode material for reversible solid oxide fuel cells (RSOFCs) applications. XRD analysis showed that the LCFCr powder is a pure crystalline phase with an orthorhombic perovskite structure and that its thermal expansion coefficient matches closely with several commonly used solid electrolytes, while TEM analysis confirmed the high purity of the LCFCr powders. The electrochemical activity of LCFCr, screen-printed on a gadolinium doped ceria electrolyte, towards both the oxygen reduction (ORR) and oxygen evolution (OER) reactions, was examined at 600–800 °C in stagnant air using a symmetrical RSOFC configuration. Under open circuit conditions, LCFCr showed a very low polarization resistance (Rp) of only 0.07 Ω cm2 at 800 °C, comparable to some of the best-performing oxide materials reported by others. The LCFCr air electrode was also found to be very stable, with very little loss in performance and no interfacial damage observed, even after 100 h at a 0.4 V (OER) and −0.4 V (ORR) overpotentials.