Investigation of a Layered Perovskite for IT-SOFC Cathodes: B-Site Fe-Doped YBa0.5Sr0.5Co2-xFexO5+delta

Abstract

Cobalt-based layered perovskite oxides have been recognized as pioneering cathode materials for intermediate-temperature solid oxide fuel cells (IT-SOFCs) due to their fast oxygen diffusion, surface exchange kinetics, and high electrical conductivity. Herein, we study novel Fe doped layered perovskites, YBa0.5Sr0.5Co2-xFexO5+δ (x = 0, 0.25, 0.5, and 0.75) in terms of their structural properties, thermal expansion behavior, electrical properties, and electrochemical performances for potential usage as a cathode. Among them, YBa0.5Sr0.5Co1.75Fe0.25O5+δ (YBSCF25, x = 0.25) not only shows enhanced structural stability but also meets the essential required properties, including an appropriate thermal expansion coefficient (TEC), chemical compatibility with the electrolyte, and suitable electrical conductivity. Moreover, power density as high as 1.5 W cm−2 at 600°C is achieved for the YBSCF25-GDC composite cathode with a full cell with a dense thin gadolinium doped ceria (GDC) electrolyte and a Ni-GDC composite anode in humidified H2. These favorable features highlight the potential of YBSCF25 as a promising cathode material for IT-SOFCs.