Impact of ceramic matrix functionality on composite electrolytes performance

• Published in: Electrochimica acta Vol. 109; pp. 701 - 709
• Main Authors: Rondão, Ana I.B., Patrício, Sónia G., Figueiredo, Filipe M.L., Marques, Fernando M.B.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 30.10.2013
• Subjects: Carbon dioxide; Ceramics; Ceria; Composite electrolytes; Composite materials; Conductors (devices); Constituents; Electrolytes; Equivalent circuit; Impedance spectroscopy; Melting; Microstructure; Impedance spectroscopy; Composite electrolytes; Ceria; Equivalent circuit
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2013.07.229

•Assessed equivalent circuits for composite electrolytes relying on constituent properties.•Confirmed impact of the ceramic matrix on performance and model behavior.•Unusual composite/interfacial effect in the case of pure CeO2-based composites.•Electrode kinetics highly sensitive to the presence/absence of oxygen. Ceria-based composite electrolytes (50 and 70vol%) including one mixture of Li and Na carbonates (1:1 molar ratio) were prepared using either pure CeO2 (modest conductor) or Gd-doped ceria (excellent oxide-ion conductor) as ceramic matrix. The composite electrolytes and their phase constituents were tested under pure CO2, air, and H2 diluted in N2, at temperatures ranging from 300 to 580°C, to study their electrical performance. Impedance spectroscopy measurements performed under these working conditions were complemented by microstructural characterization. Low temperature (below melting) impedance shows in a clear manner the relevance of the matrix functionality on the performance of these composites, but also reveals additional microstructural and even unusual composite effects. These data were used to test equivalent circuit models derived from the composite constituent properties, and to assess their potential to design composites for target functionalities at higher temperature.