Correlation between fast oxygen kinetics and enhanced performance in Fe doped layered perovskite cathodes for solid oxide fuel cells

Abstract

Many researchers have recently focused on layered perovskite oxides as cathode materials for solid oxide fuel cells because of their much higher chemical diffusion and surface exchange coefficients relative to those of ABO₃-type perovskite oxides. Herein, we study the catalytic effect of Fe doping into SmBa_0.5Sr_0.5Co₂O_5+δ on the oxygen reduction reaction (ORR) and investigate the optimal Fe substitution through an analysis of the structural characteristics, electrical properties, redox properties, oxygen kinetics, and electrochemical performance of SmBa_0.5Sr_0.5Co_2−xFe_xO_5+δ (x = 0, 0.25, 0.5, 0.75, and 1.0). The optimal Fe substitution, SmBa_0.5Sr_0.5Co_1.5Fe_0.5O_5+δ, enhanced the performance and redox stability remarkably and also led to satisfactory electrical properties and electrochemical performance due to its fast oxygen bulk diffusion and high surface kinetics under typical fuel cell operating conditions. The results suggest that SmBa_0.5Sr_0.5Co_1.5Fe_0.5O_5+δ is a promising cathode material for intermediate-temperature solid oxide fuel cells (IT-SOFCs).