Evaluation of calcium codoping in double perovskite PrBaCo2O5+δ as cathode material for IT-SOFCs

Layered perovskite oxides have attracted great attention in the electrochemical-energy field due to fast oxygen kinetics at low temperature and high electronic/ionic conductivity. Developing low-cost, high-performance electrocatalysts is a necessary path for the commercialization of electrochemical energy devices. In the current research study, PrBaCo2O5+delta codoping with Ca to substitute Pr and Ba is prepared by a modified complexing sol-gel process. New perovskite oxides Pr0.9Ca0.1Ba1-xCaxCo2O5+delta (x = 0-0.2, PCBCx) remained in a pure-phase tetragonal (P4/mmm) structure. PCBCx exhibit good chemical compatibility with Ce0.8Sm0.2O1.9 (SDC) after calcining at 1000 degrees C for 10 h. The doping of calcium ions at the Ba-site effectively improved the electrical conductivity. XPS analysis indicate that Co ions exist at +3 and +4 valence states in PCBCx samples. The thermal-expansion coefficients (TECs) of PCBCx samples decrease as the calcium ion doping concentration increasing. The polarization resistance of a PCBCx cathode on the SDC electrolyte, where x = 0-0.3 at 700 degrees C, are 0.097, 0.076, 0.069, and 0.106 Omega cm(2), respectively. The x = 0.2 cathode reveals the best electrochemical performance. The maximum power densities of the PCBC2 cathode are 712, 541, and 392 mW cm(-2) at 800, 750, and 700 degrees C, respectively. The results demonstrate an effective codoping strategy to improve conductivity, thermal stability, and electrochemical performance, and provide evidence for the great potential of prepared novel double-perovskite oxides PCBCx as solid-oxide fuel cell cathodes. (C) 2020 Elsevier Ltd. All rights reserved.