Processing of high performance composite cathodes for protonic ceramic fuel cells by exsolutionElectronic supplementary information (ESI) available. See DOI: 10.1039/c8ta10950h

• Main Authors: Rioja-Monllor, Laura, Bernuy-Lopez, Carlos, Fontaine, Marie-Laure, Grande, Tor, Einarsrud, Mari-Ann
• Format: Article
• Language: English
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/c8ta10950h

La 0.5 Ba 0.5 CoO 3− δ -BaZrO 3 (LB-BZ)-based composite materials were prepared by a modified Pechini sol-gel method combined with exsolution. Two different LB-BZ composites were prepared through two alternative thermal treatments of the precursor gel. A metastable single phase with a perovskite crystal structure was first obtained upon annealing the precursor in an inert atmosphere, and it was further transformed into a two-phase composite by in situ exsolution in air. Comparatively, direct calcination of the LB-BZ gel in air resulted in a two-phase composite with different microstructures and compositions of the two phases. The composite cathode formed by exsolution consisted of a matrix of BZ-phase with ∼45 nm grain size embedding ∼20 nm grains of LB-phase, while the composite cathode obtained by direct calcination consisted of a mixture of both phases with 50-60 nm grain size. Electrodes of symmetric half-cells were spray-coated on the BaZr 0.9 Y 0.1 O 2.95 electrolyte to examine the electrochemical performance by impedance spectroscopy. The lowest area specific resistance (ASR) was obtained for the composite cathode produced by exsolution with an excellent ASR of 1.54 Ω cm 2 at 600 °C and 18 Ω cm 2 at 400 °C and an activation energy ( E a ) of 0.60 eV in 3% moist synthetic air. This work demonstrates the potential of fabricating high performance nanocomposite cathodes with tailored chemical composition by a novel exsolution method. La 0.5 Ba 0.5 CoO 3− δ -BaZrO 3 (LB-BZ)-based composite materials were prepared by a modified Pechini sol-gel method combined with exsolution.