Physicochemical properties of Ba(Zr,Ce)O3-Δ-based proton-conducting electrolytes for solid oxide fuel cells in terms of chemical stability and electrochemical performance

Takaaki Somekawa, Yoshio Matsuzaki, Mariko Sugahara, Yuya Tachikawa, Hiroshige Matsumoto, Shunsuke Taniguchi, Kazunari Sasaki

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Abstract

To enhance the power generation efficiency of solid oxide fuel cells (SOFCs), the use of proton-conducting solid solutions of doped BaCeO3 and doped BaZrO3, with formulas of the Ba(Zr0.1Ce0.7Y0.1X0.1)O3-δ (X = Ga, Sc, In, Yb, Gd), was investigated as SOFCs electrolyte materials with respect to both chemical stability and electrical conductivity. Regarding chemical stability, the weight changes of each material were measured under a CO2 atmosphere in a temperature range of 1200 °C–600 °C. Higher chemical stability was observed for dopant ions with smaller radii. Regarding conductivity, the dependences of the total conductivities on the oxygen partial pressure and temperature were measured in the temperature range of 600 °C–900 °C. In each material, the total conductivity was proportional to the oxygen partial pressure to the 1/4 power at high oxygen partial pressures, as previously observed for accepter-doped proton-conducting perovskite-type oxides. The derived conductivities for each type of charge carrier showed that the hole conductivity increased with the ionic conductivity. Based on the measured data, the leakage current densities were calculated for SOFCs with each of the investigated electrolyte materials and an area-specific resistance of 0.383 Ωcm2. BZCYSc showed the minimum leakage current density, with a value of 3.7% of the external current density at 600 °C. Therefore, this study indicates that BZCYSc is the most desirable among the materials investigated for use as SOFCs electrolyte. However, for BZCYSc to be used as SOFCs electrolyte material, a protective layer is needed to ensure its chemical stability.

Original languageEnglish
Pages (from-to)16722-16730
Number of pages9
JournalInternational Journal of Hydrogen Energy
Volume42
Issue number26
DOIs
Publication statusPublished - Jun 29 2017

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All Science Journal Classification (ASJC) codes

  • Renewable Energy, Sustainability and the Environment
  • Fuel Technology
  • Condensed Matter Physics
  • Energy Engineering and Power Technology

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