Processing Ceramic Proton Conductor Membranes for Use in Steam Electrolysis

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).

Tailored and Improved Protonic Conductivity through Ba(ZxCe10−x)0.08Y0.2O3−δ Ceramics Perovskites Type Oxides for Electrochemical Devices

“…Both cells were fabricated using a well-established low-cost, sequential tape casting processing route. [52][53][54] Figure 7(a) presents typical open-circuit voltage (OCV) profiles obtained from both cells during the cathode reduction with varying H 2 concentrations. As observed, approximately four hours are sufficient to obtain OCV values (1.03 and 1.12 V, respectively), close to those calculated using the Nernst equation, thus verifying that both electrolyte layers are dense enough to ensure sufficient gas tightness.…”

Fabrication of multi-layered structures for proton conducting ceramic cells

“…In ref. 5 SrZr 0.5 -Ce 0.4 Y 0.1 O 3Àd is used in the anode substrate, which promotes the densication of the BZCY electrolyte layer by its high sintering shrinkage. However, one has to keep in mind that adding another material into the anode-electrolyte assembly increases the complexity of the system (e.g.…”

“…heating and power systems for houses, electric vehicles such as buses, or special cases as power supply for mobile electronic devices, 4 or for H 2 generation. 5 Interestingly, with adjusted catalytic activity at the anode side, a wide range of fuels such as ammonia and different hydrocarbons and alcohols can be used instead of hydrogen. 6 In recent years, PCFC performance has been impressively increased to more than 1.2 W cm À2 at 600 C by improving the processing of the electrolyte layer, choice of cathode materials, interface contacts through development of interlayers.…”

Recent Advances in Membrane-Based Electrochemical Hydrogen Separation: A Review

“…Although proton-conducting ceramics are still at the early stages of development, several research efforts have been made [143][144][145][146][147][148][149][150]. Overall, the process of hydrogen permeation through a dense proton conducting membrane involves several steps [122,151] where, S', BM, S" and G is the membrane surface at the inlet, the bulk membrane, the membrane surface at the outlet, and the gas, respectively.…”

“…Although proton-conducting ceramics are still at the early stages of development, several research efforts have been made [ 143 , 144 , 145 , 146 , 147 , 148 , 149 , 150 ]. Overall, the process of hydrogen permeation through a dense proton conducting membrane involves several steps [ 122 , 151 ]: H 2 gas diffusion to reaction sites on the surface of the feed side; H 2 adsorption, dissociation, and charge transfer at the membrane surface; Proton reduction and hydrogen re-association at the membrane surface where, S’ , BM , S” and G is the membrane surface at the inlet, the bulk membrane, the membrane surface at the outlet, and the gas, respectively.…”