A-site calcium-doped Pr1-xCaxBaCo2O5+δ double perovskites as cathodes for intermediate-temperature solid oxide fuel cells

The LnBaCo(2)O(5+delta) (Ln = rare earth) double perovskite cathodes possess superior electrochemical performance in intermediate-temperature solid oxide fuel cells (IT-SOFCs). However, high thermal expansion coefficients (TECs) and material costs are major challenges to their widespread applications. In this paper, a novel A-site Ca doping strategy that can suppress the spin-state transition of Co3+ is proposed to reduce the TECs and material costs of Pr1-xCaxBaCo2O5+delta (x = 0.1-0.4; PCBCO). Substitution of Ca for Pr effectively reduces the TEC from 22.2 x 10(-6) K-1 at x = 0.1 to 19.1 x 10(-6) K-1 at x = 0.3 between 100 and 800 degrees C. PCBCO exhibits good chemical compatibility with the Sm0.2Ce0.8O1.9 (SDC) electrolyte. The area specific resistances of PCBCO cathodes with x = 0.1, 0.2, and 0.3 are 0.081, 0.082, and 0.089 Omega cm(2), respectively, at 700 degrees C on the SDC electrolyte. The maximum power densities of a single cell on a 0.3 mm-thick SDC electrolyte reach 646.5, 636.8, and 620.6 mW cm(-2) at 800 degrees C for cathodes with x = 0.1, 0.2, and 0.3, respectively. The PCBCO double perovskites exhibit excellent chemical compatibility and electrochemical performance while reducing the TECs and material costs; thus, these double perovskites are promising cathode materials for applications in IT-SOFCs. (c) 2016 Elsevier B.V. All rights reserved.