Synergistic effect study of EuBa0.98Co2O5+δ-Ce0.8Sm0.2O1.9 composite cathodes for intermediate-temperature solid oxide fuel cells

A novel Ba-deficient layered perovskite EuBa0.98Co2O5+delta (EBCO) has been proposed as a high-performance cathode for intermediate-temperature solid oxide fuel cells (IT-SOFCs). Herein we report a systematic study on electrochemical properties of composite materials composed of EBCO and Ce0.8Sm0.2O1.9 (EBCO-xSDC) with x ranging from 0 to 40 wt%. The results indicate that the EBCO-xSDC composite cathodes have excellent electro-catalytic oxygen reduction reaction (ORR) activity thanks to synergistic effects of high electronic conducting EBCO phase and ionic conducting SDC electrolyte. Among all these composite cathodes, EBCO-20SDC exhibits the best cathode performance, as evidenced by a low polarization resistance value of 0.028 Omega cm(2) at 700 degrees C in air. When tested in a complete fuel cell (Ni-YSZ vertical bar YSZ vertical bar CGO vertical bar EBCO-20SDC), a much higher maximum power density of 980 mW cm(-2) is achieved, compared with that of EBCO cathode-based fuel cell (505 mW cm(-2)). Furthermore, the rate-limiting steps toward oxygen reduction reaction at the EBCO-20SDC cathode interface are determined to explore the reaction kinetics and explain the enhanced electrochemical performance. (C) 2018 Elsevier B.V. All rights reserved.