PrBa_0.5Sr_0.5Co₂O_5+δ layered perovskite cathode for intermediate temperature solid oxide fuel cells

Layered perovskite oxides have ordered A-cations localizing oxygen vacancies, and may potentially improve oxygen ion diffusivity and surface exchange coefficient. The A-site-ordered layered perovskite PrBa_0.5Sr_0.5Co₂O_5+δ (PBSC) was evaluated as new cathode material for intermediate temperature solid oxide fuel cells (IT-SOFCs). The material was characterized using electrochemical impedance spectroscopy in a symmetrical cell system (PBSC/Ce_0.9Sm_0.1O_1.9 (SDC)/PBSC), exhibiting excellent performance in the intermediate temperature range of 500-700 °C. An area-specific-resistance (ASR) of 0.23 Ω cm² was achieved at 650 °C for cathode polarization. The low activation energy (Ea) 124 kJ mol^-1 is comparable to that of La_0.8Sr_0.2CoO_3-δ. A laboratory-scaled SDC-based tri-layer cell of Ni-SDC/SDC/PBSC was tested in intermediate temperature conditions of 550 to 700 °C. A maximum power density of 1045 mW cm^-2 was achieved at 700 °C. The interfacial polarization resistance is as low as 0.285, 0.145, 0.09 and 0.05 Ω cm² at 550, 600, 650 and 700 °C, respectively. Layered perovskite PBSC shows promising performance as cathode material for IT-SOFCs.