A high-performance, cobalt-free cathode for intermediate-temperature solid oxide fuel cells with excellent CO2 tolerance

摘要

Compared with some cobalt-rich cathodes which have been proven to yield high performance in SOFCs, interest in cobalt-free cathodes has increased due to their reduced thermal expansion coefficients (TECs), high structural stability, and CO2 tolerance. In this report, a new robust Co-free complex perovskite oxide PrLa0.4Ba0.6Fe0.8Zn0.2O5+delta (PLBFZ) has been synthesized and evaluated. The TEC is 14.4 x 10(-6) K-1. With the introduction of Sm0.2Ce0.8O2 (SDC), the composite cathode PLBFZ-SDC with a mass ratio of 7:3 (PLBFZ-SDC 73) exhibited the best electrocatalytic activity for oxygen reduction under OCV conditions, with polarization values of 0.044, 0.079, 0.124, 0.251, 0.572, and 1.297 Omega cm(-2) at 800, 750, 700, 650, 600, and 550 degrees C, respectively. The power densities of the cell were 1309, 1079, 788 and 586 mW cm(-2) at 750, 700, 650, and 600 degrees C, respectively. Moreover, it appears to have good stability in air containing 1% CO2 (volume ratio) for 150 h based on Raman and polarization resistance (R-p) analysis. These results suggest that PLBFZ and its SDC composite are promising cathodes for IT-SOFCs. (C) 2016 Elsevier B.V. All rights reserved.