Abstract
Steam electrolysis constitutes a prospective technology for industrial-scale hydrogen production. The use of ceramic proton-conducting electrolytes is a beneficial option for lowering the operating temperature. However, a significant challenge with this type of electrolyte has been upscaling robust planar type devices. The fabrication of such multi-layered devices, usually via a tape casting process, requires careful control of individual layers’ shrinkages to prevent warping and cracks during sintering. The present work highlights the successful processing of 50 × 50 mm2 planar electrode-supported barium cerium yttrium zirconate BaZr0.44Ce0.36Y0.2O2.9 (BZCY(54)8/92) half cells via a sequential tape casting approach. The sintering parameters of the half-cells were analyzed and adjusted to obtain defect-free half-cells with diminished warping. Suitably dense and gas-tight electrolyte layers are obtained after co-sintering at 1350 °C for 5 h. We then assembled an electrolysis cell using Ba0.5La0.5CoO3−δ as the steam electrode, screen printed on the electrolyte layer, and fired at 800 °C. A typical Ba0.5La0.5CoO3−δ|BaZr0.44Ce0.36Y0.2O3−δ(15 μm)|NiO-SrZr0.5Ce0.4Y0.1O3−δ cell at 600 °C with 80% steam in the anode compartment reached reproducible terminal voltages of 1.4 V @ 500 mA·cm−2, achieving ~84% Faradaic efficiency. Besides electrochemical characterization, the morphology and microstructure of the layered half-cells were analyzed by a combination of high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and energy-dispersive X-ray spectroscopy. Our results also provide a feasible approach for realizing the low-cost fabrication of large-sized protonic ceramic conducting electrolysis cells (PCECs).
Highlights
Steam electrolysis has been demonstrated to be an efficient and viable method to produce high purity hydrogen using ceramics proton-conducting electrolytes (PCE) at the intermediate temperature range (400~600 ◦ C) [1,2,3,4,5]
We focused on a well-established, low cost, sequential tape casting processing route to address some of these challenges
X-ray diffraction patterns obtained for BaZr1-x-y Cex Yy O3−δ (BZCY)(54)8/9 2 and SZCY541 powders after calcination at 1300 ◦ C are shown in Figure 1a,b together with derived Rietveld refinement parameters
Summary
Steam electrolysis has been demonstrated to be an efficient and viable method to produce high purity hydrogen using ceramics proton-conducting electrolytes (PCE) at the intermediate temperature range (400~600 ◦ C) [1,2,3,4,5]. This class of electrolytes is favored for their relatively high ionic conductivity with low activation energy (
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