Performance assessment of Pr_1−xSr_xCo_0.8Cu_0.2O_3−δ perovskite oxides as cathode material for solid oxide fuel cells with Ce_0.8Sm_0.2O_1.9 electrolyte

In this paper, Pr_1−xSr_xCo_0.8Cu_0.2O_3−δ (x = 0.2, 0.3, 0.4, 0.5, 0.6) cathode material is investigated for intermediate-temperature solid oxide fuel cells (IT-SOFCs). Pr_1−xSr_xCo_0.8Cu_0.2O_3−δ oxides are prepared by the EDTA-citrate complexing method. XRD results show that there is a structural change from orthorhombic (x = 0.2 and 0.3) to cubic (x = 0.4, 0.5 and 0.6) in Pr_1−xSr_xCo_0.8Cu_0.2O_3−δ system. The electrical conductivities of all the samples are all higher than 523 S cm⁻¹ between 500 and 800 °C. The semiconductor-to-metal conductivity transition takes place at around x = 0.4. In order to further reduce thermal expansion coefficients (TECs) and improve electrochemical performance of the Pr_1−xSr_xCo_0.8Cu_0.2O_3−δ cathode, we fabricate Pr_0.5Sr_0.5Co_0.8Cu_0.2O_3−δ–x wt% Ce_0.8Sm_0.2O_1.9 (PSCC–xSDC, x = 20–60) composite cathodes. In PSCC–xSDC electrode, the TEC and polarization resistance (R_p) both decrease with the addition of SDC. The PSCC–50SDC composite cathode has the lowest R_p. The lowest R_p 0.029 Ω cm² is obtained at 800 °C for PSCC–50SDC electrode. Subsequently, we fabricate SDC (300 µm thick) electrolyte-supported fuel cell with PSCC–50SDC cathodes. The maximum power densities is 428 mW cm⁻² at 800 °C. The present results demonstrate that PSCC–50SDC composite is a promising candidate cathode for IT-SOFCs.