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A new Dy-doped BaCeO₃–BaZrO₃ proton-conducting material as a promising electrolyte for reversible solid oxide fuel cells

Lyagaeva, Julia, Danilov, Nikolay, Vdovin, Gennady, Bu, Junfu, Medvedev, Dmitry, Demin, Anatoly, Tsiakaras, Panagiotis
Journal of materials chemistry A 2016 v.4 no.40 pp. 15390-15399
air, ceramics, combustion, dysprosium, electric potential difference, electrical properties, electrochemistry, electrodes, electrolysis, electrolytes, fuel cells, hydrogen, porosity, shrinkage, yttrium
The present work describes the features of the synthesis and physicochemical and electrical properties of a new Dy-doped BaCeO₃–BaZrO₃ proton-conducting electrolyte as well as its application in a reversible solid oxide fuel cell. The electrolyte material with a composition of BaCe₀.₅Zr₀.₃Dy₀.₂O₃₋δ (BCZD) is successfully synthesized by a citrate–nitrate combustion synthesis method followed by sintering at 1450 °C for 5 h. The as-prepared ceramic materials are found to possess high ceramic quality (∼16% of total shrinkage, 98% of relative density, no open porosity), improved electrical properties (19 and 13 mS cm⁻¹ at 600 °C in wet air and wet hydrogen atmospheres, respectively) and acceptable chemical and thermal compatibilities with functional electrodes (NiO–BCZD and La₂NiO₄₊δ–BCZD). An electrochemical cell with a 30 μm thick electrolyte is fabricated by a tape calendaring method and then characterized in solid oxide fuel cell (SOFC) and solid oxide electrolysis cell (SOEC) operation modes. The electrochemical characteristics, such as open circuit voltage (OCV), current density, power density and amount of hydrogen produced by electrolysis, are obtained and then compared with literature data. On the basis of comparative analysis, it can be deduced that Dy-doped cerate–zirconates can be considered as promising alternatives to traditional Y-doped ones due to sufficient levels of output characteristics of reversible solid oxide fuel cells and good properties of these electrolytes (average ion transport numbers are more than ∼0.9) in the SOFC and SOEC operation modes at 550–750 °C.