Synthesis and characterization of M-doped ceria-ternary carbonate composite electrolytes (M = erbium, lanthanum and strontium) for low-temperature solid oxide fuel cells

• Published in: Journal of alloys and compounds Vol. 775; pp. 571 - 580
• Main Authors: Anwar, Mustafa, Muhammed Ali, S.A., Muchtar, Andanastuti, Somalu, Mahendra Rao
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 15-02-2019; Elsevier BV
• Subjects: Bandgap; Bulk density; Carbonates; Cerium oxides; Chemical synthesis; Composite electrolyte; Conductivity; Doped ceria; Electrochemical impedance spectroscopy; Electrolytes; Electrolytic cells; Erbium; Fluorite; Hydrogen; Lanthanum; Low temperature; Molten salt electrolytes; Morphology; Organic chemistry; Potassium carbonate; Proton conduction; Sintering (powder metallurgy); Sodium carbonate; Solid electrolytes; Solid oxide fuel cells; Stability analysis; Strontium oxides; Transmission electron microscopy; X-ray diffraction; Composite electrolyte; Conductivity; Carbonates; Doped ceria; Bandgap
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2018.10.076

Three different series of doped ceria-based composite electrolyte consisting of M-doped ceria (M = Ce0.85Er0.15O2-δ (ErDC), Ce0.85La0.15O2-δ (LaDC) and Ce0.95Sr0.05O2-δ (SrDC)) and ternary carbonate (mixture of Li2CO3, Na2CO3 and K2CO3) were developed as functional solid electrolytes for low-temperature solid oxide fuel cells. X-ray diffraction, transmission electron microscopy and UV–visible spectroscopy were used to analyze the chemical stability, morphology, and bandgap, respectively, of the prepared composite powders. All composite electrolytes exhibited cubic fluorite structure as a primary phase and small peaks corresponding to (Li/Na/K)2CO3 as an amorphous phase. The bulk densities of the sintered composite electrolyte pellets were in the range of 3.34 g/cm3–3.45 g/cm3. The total conductivity of the composite electrolyte materials was evaluated by electrochemical impedance spectroscopy in air and hydrogen (90 vol% N2 + 10 vol% H2) in the temperature range of 350 ºC–650 °C. The SrDC-ternary carbonate composite electrolyte showed the highest conductivity of 0.092 Scm−1 and lowest activation energy at 650 °C in hydrogen. The formation of hydrated phase from chemical interaction between the carbonates and hydrogen gas and the presence of Sr2+ and cerium ions is useful in enhancing the proton conduction in the SrDC-ternary carbonate system.
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•Er-, La-, and Sr-doped ceria with ternary carbonate are studied for the first time.•No obvious chemical reaction happens between doped-ceria and ternary carbonates.•SrDCC exhibited the highest conductivity and lowest activation energy in hydrogen.