Properties of 10% Dy-doped La2Mo2O9 and its electrolyte performance in single chamber solid oxide fuel cell

• Published in: Journal of alloys and compounds Vol. 582; pp. 780 - 785
• Main Authors: Le, Minh-Vien, Tsai, Dah-Shyang, Yao, Chi-Chieh, Lo, Jen-Chien, Vo, Thi Phung Giao
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 2014; Elsevier
• Subjects: Anodes; Cerium oxide; Chambers; Chemistry; Electrochemistry; Electrodes; Electrolytes; Exact sciences and technology; General and physical chemistry; Hydrogen reduction; LAMOX; Open circuit voltage; Oxide ion conductor; Polarization; Single chamber SOFC; Thermal expansion; Thermal expansion; Oxide ion conductor; Single chamber SOFC; LAMOX; Hydrogen reduction; Thickness; Polarization; Electrochemical properties; Dysprosium addition; Ionic conductors; Solid oxide fuel cell; Lanthanum Molybdates
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2013.08.138

•Oxide ion conductor La1.8Dy0.2Mo2O9 exhibits conductivity 0.16Scm−1 at 700°C.•Thermal expansion of La1.8Dy0.2Mo2O9 is also high 22ppm°C−1 in 480–800°C.•Single chamber SOFC based on La1.8Dy0.2Mo2O9 produces electric power 420mWcm−2.•Impedance results are analyzed to understand the influences of this ion conductor. To explore plausible applications of 10mol% Dy-doped La2Mo2O9 (LDM), we have prepared membrane-electrode assemblies (MEAs) based on this oxide ion conductor and operated them under single chamber conditions of methane and air. Material selection is centered on matching thermal expansion of the LDM electrolyte, joined with an anode support of nickel and ceria cermet and a graded cathode of samarium strontium cobaltite plus ceria. The performance test results indicate that both open circuit voltage and ohmic loss increase with increasing LDM thickness, leading an optimal LDM thickness 60μm. This MEA of 60μm thick LDM generates peak power 330mWcm−2 at 700°C, which can be upgraded to 420mWcm−2 through promoting the anode activity. Impedance analysis indicates the electrode improvements are effective, but have limitations, because the major polarization loss resides in the LDM electrolyte. High electrolyte polarization loss originates from two weaknesses of LDM, excessive thermal expansion and vulnerability to hydrogen reduction.