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

Abstract 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 CO 2 tolerance. In this report, a new robust Co-free complex perovskite oxide PrLa 0.4 Ba 0.6 Fe 0.8 Zn 0.2 O 5+δ (PLBFZ) has been synthesized and evaluated. The TEC is 14.4 × 10 −6  K −1 . With the introduction of Sm 0.2 Ce 0.8 O 2 (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 Ω cm −2 at 800, 750, 700, 650, 600, and 550 °C, respectively. The power densities of the cell were 1309, 1079, 788 and 586 mW cm −2 at 750, 700, 650, and 600 °C, respectively. Moreover, it appears to have good stability in air containing 1% CO 2 (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.