High-Performance La0.5Ba0.5Co1/3Mn1/3Fe1/3O3−δ-BaZr1−zYzO3−δ Cathode Composites via an Exsolution Mechanism for Protonic Ceramic Fuel Cells

A novel exsolution process was used to fabricate complex all-oxide nanocomposite cathodes for Protonic Ceramic Fuel Cells (PCFCs). The nanocomposite cathodes with La0.5Ba0.5Co1/3Mn1/3Fe1/3O3−δ-BaZr1−zYzO3−δ nominal composition were prepared from a single-phase precursor via an oxidation-driven exsol...

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Bibliographic Details
Published in:Inorganics 2018-09, Vol.6 (3), p.83
Main Authors: Rioja-Monllor, Laura, Ricote, Sandrine, Bernuy-Lopez, Carlos, Grande, Tor, O’Hayre, Ryan, Einarsrud, Mari-Ann
Format: Article
Language:English
Subjects:
cathode
Cathodes
Cations
Chemical composition
Dielectric properties
Electrical conductivity
Electrical resistivity
Electrochemical analysis
Electrodes
Electrolytes
Electrolytic cells
exsolution
Fuel cells
Heat treatment
Nanocomposites
Nanoparticles
Organic chemistry
Oxidation
Oxygen ions
Percolation
Perovskites
Phase composition
Phases
Powder
Precursors
proton ceramic fuel cells (PCFC)
Solid oxide fuel cells
Spectroscopy
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Summary:A novel exsolution process was used to fabricate complex all-oxide nanocomposite cathodes for Protonic Ceramic Fuel Cells (PCFCs). The nanocomposite cathodes with La0.5Ba0.5Co1/3Mn1/3Fe1/3O3−δ-BaZr1−zYzO3−δ nominal composition were prepared from a single-phase precursor via an oxidation-driven exsolution mechanism. The exsolution process results in a highly nanostructured and intimately interconnected percolating network of the two final phases, one proton conducting (BaZr1−zYzO3−δ) and one mixed oxygen ion and electron conducting (La0.5Ba0.5Co1/3Mn1/3Fe1/3O3−δ), yielding excellent cathode performance. The cathode powder is synthesized as a single-phase cubic precursor by a modified Pechini route followed by annealing at 700 °C in N2. The precursor phase is exsolved into two cubic perovskite phases by further heat treatment in air. The phase composition and chemical composition of the two phases were confirmed by Rietveld refinement. The electrical conductivity of the composites was measured and the electrochemical performance was determined by impedance spectroscopy of symmetrical cells using BaZr0.9Y0.1O2.95 as electrolyte. Our results establish the potential of this exsolution method where a large number of different cations can be used to design composite cathodes. The La0.5Ba0.5Co1/3Mn1/3Fe1/3O3−δ-BaZr0.9Y0.1O2.95 composite cathode shows the best performance of 0.44 Ω∙cm2 at 600 °C in 3% moist synthetic air.
ISSN:2304-6740
2304-6740
DOI:10.3390/inorganics6030083