EuBaCo2O5+δ-Ce0.9Gd0.1O2-δ composite cathodes for intermediate-temperature solid oxide fuel cells: high electrochemical performance and oxygen reduction kinetics

The characteristics and electrochemical performance of double perovskite EuBaCo2O5+delta (EBCO) have been investigated as a composite cathode for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The thermal expansion coefficients can be effectively reduced in the case of EBCO-Ce0.9Gd0.1O2-delta (CGO) composite cathodes. No chemical reactions between EBCO cathode and CGO electrolyte are observed after sintering at 1000 degrees C for 24 h. The maximum electrical conductivities of EBCO-CGO materials reach 28-77 S cm(-1) with the change of CGO weight ratio from 40 wt. % to 5 wt. %. Among all these components, the EBCO-10 wt. % CGO (EBCO-10CGO) composite cathode gives the lowest area-specific resistance of 0.055 and 0.26 Omega cm(2) in air at 700 and 600 degrees C, respectively. The maximum power density of Ni-CGO anode-supported single cell consisted of the EBCO-10CGO composite cathode and CGO electrolyte achieves 0.81 W cm(-2) at 700 degrees C. These results indicate that the EBCO-10CGO composite materials can be used as a promising cathode candidate for IT-SOFCs. Furthermore, the rate-limiting steps for the oxygen reduction reaction at the EBCO-10CGO composite cathode interface are determined to be the charge transfer and dissociation of adsorbed molecule oxygen processes. (c) 2015 Elsevier Ltd. All rights reserved.