Oxygen vacancies-rich iron-based perovskite-like electrodes for symmetrical solid oxide fuel cells

Abstract

Oxygen vacancies-rich iron-based perovskite-like oxides LaxSr3-xFe2O7-δ (x = 0, 0.25, 0.5) have been studied towards application as both anode and cathode materials for symmetrical solid oxide fuel cells (SSOFCs) at intermediate temperatures utilizing their excellent thermo-chemical structural stability. The conduction mechanism of LaxSr3-xFe2O7-δ was investigated according to the effect of La content on electrical conductivity and oxygen nonstoichiometry. Consequently, LaxSr3-xFe2O7-δ was used simultaneously as reversible symmetrical electrodes for YSZ electrolyte supported SSOFCs with GDC buffer layers. The maximum power density of LaxSr3-xFe2O7-δ-GDC symmetrical electrodes increased from 350 mW cm−2 to 480 mW cm−2 at 800 °C, and the corresponding cell polarization resistance decreased from 0.18 Ω cm2 to 0.16 Ω cm2, respectively. The enhanced performance is attributed to the improved electrical conductivity and electro-catalytic activity by the partial substitution of Sr with La. These results demonstrate that new iron-based perovskite-like oxides are promising for applications in intermediate temperatures SSOFCs.