Planar proton-conducting ceramic cells for hydrogen extraction: Mechanical properties, electrochemical performance and up-scaling

Proton-conducting ceramics, which selectively separate H2 from any hydrogen-containing gas could play a role in the future of the growing hydrogen market. In recent years, membrane technologies related to H2 extraction became attractive solutions to produce pressurized high-purity hydrogen. Yttrium-doped barium zirconate/cerate materials (BaCexZr1-x-yYyO3-$) are among the most studied and used materials. In this study, symmetrical cells consisting of a protonic electrolyte (BaCe0.2Zr0.7Y0.1O3-$ (BCZY27), 10-15 mm in thickness) surrounded by two cermet electrodes (BCZY27-Ni (50-50 vol%), 150 mm) were prepared for H2 extraction applications. The cells were prepared via tape-casting and cosintered at 1575 degrees C. The cells were up-scaled to an area of 135 cm2. The fracture toughness of the cermet electrodes was determined to be 2.07 (+/- 0.05) MPa . m1/2 at room temperature using the double torsion technique. Impedance spectra were recorded on the symmetrical cells between 650 and 800 degrees C in 3% humidified 50% H2/50% N2 atmosphere and at 650 degrees C varying the hydrogen partial pressure (20% < pH2<100%). In 50% H2/50% N2 with 3% H2O the cells demonstrated an ohmic resistance of 0.59 and 0.44 U cm,2 an average electrode polarization resistance of 0.10 and 0.09 U cm2 (per one electrode) at 650 and 800 degrees C, respectively. Moreover, a stability test was performed over 400 h highlighting the stable electrochemical properties of the symmetrical membranes.

Automated summary

Proton-conducting ceramics have significant potential in the hydrogen market. Symmetrical cells based on barium zirconate/cerate materials demonstrate excellent electrochemical performance and stability for H2 extraction applications.