Intrinsic and extrinsic compositional effects in ceria/carbonate composite electrolytes for fuel cells

• Published in: International journal of hydrogen energy Vol. 36; no. 5; pp. 3704 - 3711
• Main Authors: Ferreira, Ana S.V., Soares, Cátia M.C., Figueiredo, Filipe M.H.L.R., Marques, Fernando M.B.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-03-2011; Elsevier
• Subjects: Alkaline carbonate; Alternative fuels. Production and utilization; Applied sciences; Carbonates; Ceria; Charge transport; Chemical composition; Diffraction; Electrolytes; Energy; Exact sciences and technology; Fuel cell; Fuel cells; Fuels; Humidity; Hydrogen; Ionic conductivity; Liquids; Mechanosynthesis; Phase composition; Reflectance; Fuel cell; Mechanosynthesis; Ceria; Humidity; Ionic conductivity; Alkaline carbonate; Scanning electron microscopy; Phase composition; Hydrogen; Lithium; Cerium oxide; Infrared spectrometry; Chemical composition; Carbonates; X ray diffractometry; Microstructure; Ceramic materials; Electrochemical impedance spectroscopy
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2010.12.025

Composite ionic conductors for fuel cells were produced by combination of one ceria-based ceramic electrolyte and various mixtures of Na and Li carbonates, using several processing routes. These materials were characterized by impedance spectroscopy, scanning electron microscopy with energy dispersive spectroscopy, X-ray diffraction and Fourier transform infrared spectroscopy with attenuated total reflectance. The chemical composition of the mixed carbonates and the processing route were influential in the development of impressive conductivity levels (close to 0.1 S/cm) at modest temperatures (below 600 °C), suggesting a complex role of chemical composition (Na/Li ratio), phase composition (solid/liquid ratio), processing route (mechanothermal history) and microstructure. Furthermore, exposure to humidity showed formation of OH groups. Such hydrogenated species are believed to increase the complexity of the global surface processes and charge transport mechanisms where several native and foreign species may play a significant role.