Proton-conducting Solid Oxide Electrolysis Cell Research Articles

Effect of CuO–ZnO catalyst layer on proton-conducting electrochemical cell reactor for CO2 reduction reaction

A catalyst layer is coated on the fuel electrode in a proton-conducting solid oxide electrolysis cell reactor, which can optimize electrochemical performance and expand the application range of the reactor. In this work, CuO–ZnO catalyst is prepared by oxalate co-precipitation method and combined with a single cell to obtain a reactor with the structure of La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) ǀ BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (BZCYYb) ǀ NiO-BZCYYb (active layer) ǀ NiO-BZCYYb (support layer) | CuO–ZnO (catalyst layer). The electrolysis current density of this reactor with humid air as oxidant and 20%CO2–80%H2 as fuel is 2751 mA cm−2 under 1.3 V at 750 °C. It operates steadily for 138 h under 1.3 V electrolysis at 650 °C, which is better than the reactor without a catalyst layer under this condition. Additionally, CO and CH4 are detected in the exhaust gas on the fuel electrode side, and the CO selectivity reaches over 90% at 750-550 °C.

Current Leakage and Faradaic Efficiency Simulation of Proton-Conducting Solid Oxide Electrolysis Cells

Proton conducting solid oxide electrolysis cells (H-SOEC) have advantages over its oxygen-ion-conducting (O-SOEC) counterpart due to lower operating temperature (e.g. 300-700oC), relatively lower activation energy, and easier gas separation [1, 2]. However, it suffers from low Faradaic efficiency led by the internal current leakage. Protonic ceramics like BaZr0.90Y0.10O3 (BZY) are generally mixed proton, oxygen ion and electron hole conducting oxides, in which the transference number of each charge carrier depends on the material composition, operating temperature, atmosphere, and polarization current density. Experimental results have been reported that BZY shows significant p-type electronic leakage [3] across the electrolyte resulting in a flux of hydrogen from the negative electrode to the positive electrode and reducing the Faradaic efficiency. However, the fundamental understanding of the formation of electronic charge carriers during electrolysis operation is still unknown.In this research, we will simulate H-SOEC with BZY electrolyte with defect chemistry and Nernst-Planck charge conservation [4] to couple thermodynamic equilibrium of both electrodes under polarized operating conditions. Three mobile charge carriers will be considered in BZY electrolyte, including proton, oxide ion and electron hole, which is balanced with the dopant concentration . The thermodynamic equilibrium will be used to solve for charge species concentration in different gas atmosphere. The thermodynamic parameters will be validated by experimental data of BZY proton concentration [5] under different operating temperature and different O2 or H2O partial pressures. The mobility of each charged species will be validated by overall conductivity of BZY [6]. Then, the model will be used to project internal electronic current leakage and Faradaic efficiency from open circuit voltage to Nernst potential and beyond (as shown in Fig. 1). The correlation between Faradaic efficiency and operating current density will be established to explain the experimental observations. Ultimately, the model could help establish strategies to minimize electronic leakage by tailoring the composition of the electrolyte, optimizing device architecture and manipulating P-SOEC operating conditions.

Dependence of Faraday Efficiency on Operation Conditions and Cell Properties for Proton Ceramic Electrolysis Cells

Proton-conducting solid oxide electrolysis cells (p-SOECs) have attracted much attention due to their low operating temperature and low degradation rate compared with conventional oxygen-ion conducting solid oxide electrolysis cells (o-SOEC). However, p-SOECs suffer from relatively low Faradaic efficiency due to the electronic leakage of the electrolyte. Using an electrolyte charge carrier transport model, we quantified the dependence of Faraday efficiency on the electrolysis operation conditions. Our model describes the transport of charge carriers in the electrolyte when the polarization resistance can not be neglected during cell operations. By accounting for the overpotentials at the interface of electrode and electrolyte in the model, we found that the Faraday efficiency decreases with the increasing current densities at electrolysis mode for both BZY20 and BCZYYb. Our results provide significant insights into the development of highly efficient p-SOECs.

Oxygen Electrode PrBa0.5Sr0.5Co1.5Fe0.5O5+δ-BaZr0.1Ce0.7Y0.1Yb0.1O3-δ with Different Composite Proportions for Proton-Conducting Solid Oxide Electrolysis Cells.

Proton-conducting solid oxide electrolysis cell (H-SOEC), as a hydrogen production device using proton conductor oxides as an electrolyte, has gained attention due to its various advantages of being more suitable for operating conditions at intermediate and low temperatures. However, its commercialization urgently needs to address the issue of insufficient catalytic activity of the oxygen electrode at lower temperatures. In this work, PrBa0.5Sr0.5Co1.5Fe0.5O5+δ-BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (PBSCF-BZCYYb) series composite materials (denoted as PBSCF-BZCYYb46, PBSCF- BZCYYb55, and PBSCF-BZCYYb64 based on the mass ratios of PBSCF and BZCYYb as 4:6, 5:5, and 6:4, respectively) are prepared and applied as oxygen electrodes for H-SOECs. The H-SOECs with the structure of PBSCF-BZCYYb|BZCYYb|NiO-BZCYYb (active layer)|NiO-BZCYYb (support layer) are prepared and recorded as Cell 1, Cell 2, and Cell 3 with PBSCF-BZCYYb46, PBSCF-BZCYYb55, and PBSCF-BZCYYb64 as oxygen electrodes. The H-SOECs exhibit electrolysis current densities of 669.00, 743.80, and 503.30 mA cm-2 under 1.3 V at 650 °C, respectively. The cells also show considerable stability in the constant voltage electrolysis of 179.5, 152.8, and 83.0 h, respectively. Through the comparison of various electrochemical properties, PBSCF-BZCYYb55 is considered the most promising oxygen electrode material in this work.

Current Leakage and Faradaic Efficiency Simulation of Proton-Conducting Solid Oxide Electrolysis Cells

In this study, we simulated BZY electrolyte-supported proton-conducting solid oxide cell by coupling surface defect chemistry reaction with charged species transport. We validated the model parameters by concentration as a function of temperature, conductivity under dry and wet oxygen as a function of oxygen partial pressure and temperature. The results indicate that the high electron-hole mobility (diffusivity) is mainly responsible for the high leaking current under high temperatures. The Faradaic efficiency stays low or even negative under low operating voltage or high temperature and plateaus as the cell voltage increases. The model developed in this study is a useful tool to understand the leaking current in BZY electrolyte and provide design strategies to avoid/mitigate such significant inefficiency for water electrolysis operation.

PrBa0.5Sr0.5Co1.5Fe0.5O5+δ as air electrode for proton-conducting solid oxide cells

Proton-conducting solid oxide cell (H–SOC) is suitable for operation at lower temperatures. However, its commercialization still faces the problem of insufficient catalytic activity of air electrode. Here a triple ionic-electronic conductor PrBa0.5Sr0.5Co1.5Fe0.5O5+δ (PBSCF) is synthesized by glycine-nitrate method, and the PBSCF slurry was screen printed onto the surface of half-cell which is fabricated by aqueous co-tape casting to obtain the single cell with the structure of PBSCF ǀ BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (BZCYYb) ǀ NiO-BZCYYb (active layer) ǀ NiO-BZCYYb (support layer). The peak power density of the single cell with dry air as oxidant and hydrogen as fuel at 750, 700, and 650 °C are 958.75, 872.78, and 709.22 mW cm−2, respectively. When the atmosphere is 20%H2O+80%air at air electrode side and hydrogen at fuel electrode side, the single cell operating as a proton-conducting solid oxide electrolysis cell shows high electrolysis current densities of 4299.4, 2744.6, 1711.8, and 974.6 mA cm−2 under 1.3 V at 750, 700, 650, and 600 °C respectively. Additionally, during the constant voltage electrolysis, the cell shows a good stability in 78 h at 650 °C. The results show that PBSCF is potential as air electrode of H–SOCs, especially in solid oxide electrolysis cell mode.

Interface Problems in Solid Oxide Electrolysis Cells

In this talk, I introduce topics, that I have been working on, in solid oxide electrolysis cells involving complicated interfacial structures and dynamics of interfaces. Then I will focus on my recent work on nickel (Ni) particle migration in electrodes consisting of Ni, yttria-stabilized zirconia (YSZ), and pores during the operation of oxygen-ion conducting solid oxide electrolysis cells (o-SOECs) and Faraday efficiency in proton-conducting solid oxide electrolysis cells (p-SOECs) under electrolysis operations. SOECs can have a significant impact on climate change over the next decade and beyond, in applications such as balancing renewable grid electricity via electrolytic fuel production. However, long-term performance degradation remains a key issue that may limit further implementation of O-SOECs, and the dependency of operation conditions on Faraday efficiency in P-SOECs has been under debate. In particular, in Ni/YSZ/pore electrode of O-SOEC, a phase-field model is proposed that employs the Ni-YSZ 3D microstructure as the initial condition and large-scale numerical simulation is implemented that predicts the directional Ni migration. The results are thus directly comparable to experimental observations. Quantitative predictions of the evolution of the Ni/YSZ/pore system's microstructures due to Ni particles' migration are studied through theoretical analysis and data analysis. In P-SOECs, an electrochemical model is proposed to study the dependency of Faraday efficiency on operation conditions for P-SOECs with yttrium-doped barium zirconates (BZY) and co-doping barium zirconate-cerate oxides with ytterbium and yttrium (BCZYYb) as electrolytes respectively. Our numerical predictions are verified by experimental results obtained in INL. An optimal structure of electrolyte is proposed to boost the Faraday efficiency in P-SOECs.

The effect of sintering aids on BaCe0·7Zr0·1Y0.1Yb0.1O3-δ as the electrolyte of proton-conducting solid oxide electrolysis cells

Proton-conducting solid oxide electrolysis cells (H-SOECs) are attracting attentions of researchers due to their unique advantages. The proton-conducting material BaCe0·7Zr0·1Y0.1Yb0.1O3-δ (BZCYYb) has both the advantages of barium ceria-based and barium zirconate-based materials. BZCYYb material usually is synthesized by solid-state reaction (SSR) method, hence the densification of this electrolyte material is the key to restrict the application of H-SOECs. In this paper, effects of adding 1 wt% of different sintering aids (NiO, CuO, ZnO) to BZCYYb on the grain size and the conductivity are investigated. After adding 1 wt% of NiO and CuO sintering aids, BZCYYb electrolyte achieves ideal density. The electrical conductivity of four samples (BZCYYb without adding sintering aid, BZCYYb with 1 wt% NiO, CuO, ZnO, respectively) is tested under different steam concentrations of air, nitrogen, hydrogen, and nitrogen-hydrogen mixture. The conductivity increased after the sintering aid is added. With the increase of steam concentration, the conductivity decreased slightly and then increased due to electron holes under oxygen atmosphere with steam at high temperature. In other atmospheres, the conductivity increases with the steam concentration. In the atmosphere of 20 vol% H2O-Air and H2, the conductivity of the BZCYYb samples with 1 wt% CuO is about 1.087 × 10−2 S cm−1 and 9.02 × 10−3 S cm−1 at 650 °C, and the conductivity of the BZCYYb samples with 1 wt% NiO is 1.277 × 10−2 S cm−1 and 8.24 × 10−3 S cm−1, respectively. However, compared with NiO, CuO has advantages in promoting hydration reaction and proton conduction of BZCYYb electrolyte.

Performance improvement of the proton-conducting solid oxide electrolysis cell coupled with dry methane reforming

The proton-conducting solid oxide electrolysis cell (H-SOEC) is a clean technology for syngas production from H2O and CO2 through electrochemical and chemical reactions. However, it provides a low CO2 conversion and produces a syngas product with a high H2O content. To improve the H-SOEC for syngas production, H-SOEC coupled with a dry methane reforming process (H-SOEC/DMR) was proposed in this work. The process flowsheet of the H-SOEC/DMR was developed and further used to evaluate the performance of the H-SOEC/DMR process. From the performance analysis of the H-SOEC/DMR process, it was found that the CO2 and CH4 conversions were higher than 90% and 80%, respectively, when the process was operated in the temperature range of 1073–1273 K. In addition, the result showed that a syngas product with a low H2O content could be obtained. Energy efficiency was then considered and the results indicated that the highest energy efficiency of 72.80% could be achieved when the H-SOEC/DMR process was operated at a temperature of 1123 K, pressure of 1 atm, and current density of 2500 A m−2. Based on a pinch analysis, a heat exchanger network was applied to the H-SOEC/DMR process that improved the energy efficiency to 81.46%. Finally, an exergy analysis was performed and showed that the H-SOEC/DMR unit had the lowest exergy efficiency as a high-temperature exhaust gas was released.

(Invited) Advanced Electrode and Electrolyte Materials for Proton Conducting Solid Oxide Electrolysis Cells

Hydrogen production by using proton-conducting solid oxide electrolysis cells (SOECs) has been acknowledged as a promising approach to effectively utilize the clean renewable energies and nuclear heat and to decarbonize. To deliver fast and durable hydrogen production during intermediate-to-low temperature (400~600○C) operation, some critical components such as oxygen electrode and electrolyte are important for achieving high electrolysis performance under realistic conditions, particularly in high steam pressure. In this presentation, the recent developments on praseodymium cobaltite-based PrNixCo1-xO3-δ electrode and Sc-doped BaZrO3-based electrolyte are respectively introduced. The triple conductive electrode demonstrates high activity and stability towards water splitting reaction, and to down-select the optimal composition, a series of optimization study have been carried out to understand structure-property relationship, chemical/performance stability in high steam condition, and interfacial stability. For electrolyte, the hydration behavior, proton conductivity, transference number, and chemical stability are studied to disclose the effect of dopant on increasing effective proton concentration, and the underlying mechanism is also investigated by experimental characterizations.

Enhanced Performance of Protonic Solid Oxide Steam Electrolysis Cell of Zr-Rich Side BaZr0.6Ce0.2Y0.2O3-δ Electrolyte with an Anode Functional Layer.

Proton-conducting solid oxide electrolysis cells (H-SOEC) containing a 15-μm-thick BaZr0.6Ce0.2Y0.2O3−δ (BZCY622) electrolyte thin film, porous cathode cermet support, and La0.6Sr0.4Co0.2Fe0.8O3−δ anodes were fabricated using a reactive cofiring process at approximately 1400 °C. Steam electrolysis was conducted by supplying wet air to the anode at a water partial pressure of 20 kPa. The performance was evaluated using electrochemical measurements and gas chromatography. At 600 °C, the cells generated an electrolysis current of 0.47 A cm–2 at a 1.3 V bias while the Faradaic efficiency reached 56% using 400 mA cm–2. The electrolysis performance was efficiently improved by introducing a 40-nm-thick La0.5Sr0.5CoO3−δ (LSC) nanolayer as an anode functional layer (AFL). The cells with LSC AFL produced an electrolysis current of 0.87 A cm–2 at a 1.3 V bias at 600 °C, and the Faradaic efficiency reached 65% under 400 mA cm–2. Impedance analysis showed that the introduction of the AFL decreased the ohmic resistances and improved interfacial proton transfer across the anode/electrolyte interface and polarization resistances related to the anode reaction. These results demonstrate opportunities for future research on AFL to improve the performance of H-SOECs with Zr-rich BaZrxCe1–x–yYyO3−δ electrolytes.

SrxTi0.6Fe0.4O3−δ (x = 1.0, 0.9) catalysts for ammonia synthesis via proton-conducting solid oxide electrolysis cells (PCECs)

The high concentration of OVs and active sites of S0.9TF promote its high NRR activity. The proton-conducting solid oxide electrolysis cells (PCECs) with S0.9TF material as a cathode showed a high output (bar) and durability (line).

Structure, synthesis, properties and solid oxide electrolysis cells application of Ba(Ce, Zr)O3 based proton conducting materials

Ba(Ce, Zr)O3 based proton-conducting oxides have experienced a surge of attention in the past because of their promising applications in proton-conducting solid oxide electrolysis cells (H+-SOECs). As proton conductor perovskite oxides, Ba(Ce, Zr)O3 based materials demonstrate potential to offer lower activation energy and higher proton transfer properties in low-temperature than oxygen ion conductor perovskite oxides as a result of the smaller ion radius of proton. Herein, a review of the current research progress on Ba(Ce, Zr)O3 based materials, including structural, materials synthesis approaches, conductivity, stability properties, and applications related to H+-SOECs is presented. This review focuses on modification strategies, including enhancing conductivity and chemical stability via the substitution of the B-site element, to improve the performance of H+-SOECs. Finally, more attention should be given to current leakage, performance and long-term stability of H+-SOECs in the future.

Ruddlesden–Popper-Structured (Pr0.9La0.1)2(Ni0.8Cu0.2)O4+δ: An Effective Oxygen Electrode Material for Proton-Conducting Solid Oxide Electrolysis Cells

Proton-conducting solid oxide electrolysis cells (H-SOECs) have attracted a lot of attention due to their high efficiency, energy-saving ability, and environmental friendliness. The ideal H-SOEC ox...

Energy storage and hydrogen production by proton conducting solid oxide electrolysis cells with a novel heterogeneous design

The proton-conducting solid oxide electrolysis cell is a promising technology for energy storage and hydrogen production. However, because of the aggressive humid condition in the air electrode side, the stability of electrolysis cells is still a concern. In addition, the energy efficiency needs further improvement before its practical application. In this work, considering both stability and energy efficiency, a novel heterogeneous design is proposed for proton-conducting solid oxide electrolysis cells. In this heterogeneous design, the merits of proton-conducting materials can be taken advantage of and the drawbacks of proton-conducting materials can be circumvented synchronously, resulting in better stability and higher efficiency of electrolysis cells. The feasibility and advantages of the heterogeneous design are demonstrated in electrolysis cells with yttrium and zirconium co-doped barium cerate-nickel as the fuel electrode material and yttrium-doped barium zirconate as the electrolyte material by experiment and modeling. The experimental results demonstrate that compared with the conventional homogeneous design, this novel design can efficiently improve the proton conductivity of the yttrium-doped barium zirconate electrolyte (from 0.88 × 10−3 S cm−1 to 2.13 × 10−3 S cm−1 at 873 K) and slightly improve the ionic transport number of the electrolyte (from 0.941 to 0.964 at 873 K), resulting in better electrochemical performance. The electrolysis cells with this design also show good stability. Moreover, the simulation results show that the faradaic efficiency and energy efficiency of electrolysis cells are improved by applying this novel design. These impressive results demonstrate that heterogeneous design is a rational design for high-performance and efficient proton-conducting solid oxide electrolysis cell.

Performance Modeling of Hydrogen-Production Electrolysis Cells for Scaling up Electrochemical Materials

This presentation will introduce modeling methods of an electrochemical cell and correspondent computational tools that enable the implementation of materials into a component design for assessing their performance, lifetime and reliability through high-fidelity modeling methods. The component modeling tools use ANSYS software as a solution framework, by adding fundamental thermochemical, electrochemical, and thermomechanical models, for simulations from basic material properties to a full-product design. The thermochemical and electrochemical modeling tools were developed from the fundamental transport and chemical processes from basic material performance data and correlations to reduce prediction uncertainties. By incorporating the specific mathematical descriptions for hydrogen-production processes, the modeling methods can be adapted to various electrolysis cell types as a general approach for electrolysis device design or performance optimization, because a common solver platform is used and expands the functionality of the computational fluid dynamics (CFD) software, ANSYS/Fluent with an add-on electrochemical module through Fluent’s User Defined Function (UDF). Particularly, we have developed models for high-temperature electrolysis (HTE) using proton-conducting solid oxide electrolysis cell (H-SOEC), low-temperature electrolysis (LTE) of proton-exchange-membrane electrolysis cell (PEMEC), and carbon-dioxide reduction (CO2R) cells.These multi-scale electrochemical modeling tools have been used for component performance simulations and are for studying material implementation at the cell and stack level. Appropriate mathematical descriptions of the electrochemical and thermochemical processes were developed for a given system based on the underlying material performance taken from either experimental data or theoretical modeling results. The modeling practices were previously successfully applied to fuel cell design and transformed for electrolysis cell design. The integral modeling tool provides insights into new materials or components that can be or are being implemented into electrochemical cell and stacks. Furthermore, the computational tools can support the electrolyzer design, performance, degradation and life cycle predictions, and may accelerate the material implementation into a product with proper design and optimum performance conditions.The presentation will show that the computational modeling links experimental materials research with a component or product using high-fidelity thermochemical and electrochemical models. The focus of this presentation will be on the modeling method and results for the H-SOEC electrolysis cells. The approach will facilitate material R&D in general and improve the computational tools to support industry for predicting product and life cycle performance. Validation of component performance and system integration results against prototype designs can allow iterative improvements to the model and to various types, processes, and scales of systems.

(Invited) High Performing and Stable Proton-Conducting Solid Oxide Electrolysis Cells with Triple Conducting Anodes

Proton-conductors BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (BZCYYb) and La2Ce2O7 (LDC) are combined to create an interface active and steam-tolerant electrolyte for high-performance proton-conducting solid oxide electrolysis cells. LDC shows good chemical compatibility with BZCYYb. The readily fabricated LDC/BZCYYb bilayer electrolyte can be densified at a temperature as low as 1300oC vs. ~1600oC for the benchmark vapor-stable BaZr0.8Y0.2O3-δ electrolyte. With Pr2NiO4+δ as the anode and Ni as the cathode catalyst, this bilayer electrolyte cell yields a current density of 975 mA/cm2 and 300 mA/cm2 under a 1.3 V applied potential at 700oC and 600oC, respectively. This performance is among the best of all H-SOECs equipped with a chemically stable electrolyte so far. BZCYYb layer in the bilayer electrolyte promotes the hydrogen evaluation reaction at the cathode side, resulting in a 108% improvement over the cell without this layer. The LDC layer, on the other hand, effectively protects this functional BZCYYb layer from high concentration of vapor in a practical SOEC operation condition. The cell without LDC layer shows degradation in terms of increase in the electrolyzing potential from 1.07 V to 1.29 V during a 400 mA/cm2 operation at 700oC. In contrast, the bilayer electrolyte cell maintains the same electrolyzing potential of 1.13 V under the same conduction for a 102 h operation. These findings demonstrate that this synergic bilayer electrolyte design could be a vital strategy to overcome the dilemma between performance and stability faced by the current benchmark Zr- or Ce-rich Ba(CeZr)O3-δ electrolytes, achieving good performance and stability at the same time.

A Proton Conducting Solid Oxide Electrolysis Cell with Tri-Doping Electrolyte and Three-Phase Conducting Steam Electrode for Sustainable Hydrogen Production

Proton conducting solid oxide electrolysis cell (P-SOEC) is an emerging technology that enables sustainable hydrogen production at reduced operating temperatures (400~600 ○C). Economically competitive P-SOEC systems have distinct advantages over conventional oxygen-ion conducting counterpart (O-SOEC), but further technology development and widespread market acceptance will require continuous innovation of materials in order to improve cell performance, enhance system lifetime and reduce cost. In this work, a new type of tri-doping barium-zirconium-cerate electrolyte and a triple phase conducting steam electrode are explored as material candidates. The material synthesis, pellet sintering, and electrical conductivity are carried out to evaluate the feasibility as an electrolyte. For the triple phase conducting electrode, the conduction behavior and catalytic activity towards water splitting reaction are studied. In addition, these two materials are incorporated into P-SOEC button cells and the electrochemical performance is evaluated under different operating conditions (temperature, humidity, feed gas composition, etc). The long-term durability in high steam pressure is also carried out to examine the stability of the material system. Such an early-stage R&D showed feasibility of hydrogen production systems for field operations and the ability to cost effectively produce hydrogen at the scale needed to support military operations.

(Invited) Performance Modeling of Hydrogen-Production Electrolysis Cells for Scaling up Electrochemical Materials

This presentation will introduce modeling methods of an electrochemical cell and correspondent computational tools that enable the implementation of materials into a component design for assessing their performance, lifetime and reliability through high-fidelity modeling methods. The component modeling tools use ANSYS software as a solution framework, by adding fundamental thermochemical, electrochemical, and thermomechanical models, for simulations from basic material properties to a full-product design. The thermochemical and electrochemical modeling tools are developed from the fundamental transport and chemical processes from basic material performance data and correlations to reduce prediction uncertainties. By incorporating the specific mathematical descriptions of hydrogen-production processes, the modeling methods can be adapted to various electrolysis cell types as a general tool for electrolyzer design or performance optimization, because a common solver platform was used and expands the functionalities of the computational fluid dynamics (CFD) software, ANSYS/Fluent with an add-on electrochemical module based on Fluent User Defined Function (UDF). In particularly, we have developed models for high-temperature electrolysis (HTE) using proton-conducting solid oxide electrolysis cell (H-SOEC), low-temperature electrolysis (LTE) of proton-exchange-membrane electrolysis cell (PEMEC), and carbon-dioxide reduction (CO2R) cells. The multi-scale electrochemical modeling tools have been used for component performance simulations and are for material scale-up and implementation in cell and stack level. Appropriate mathematical descriptions of the electrochemical and thermochemical processes need to be developed for a given system based on the underlying material performance from either experimental data or theoretical modeling results. The modeling practices were previously successfully applied for fuel cell design and transformed to electrolysis cells. The integral modeling tool provides insights for the new materials or components to be implemented into electrochemical cell and stacks. The computational tools can support the electrolyzer design, performance, degradation and life cycle predictions, and can accelerate the material implementation into a product with proper design and optimum performance. The presentation will show that the computational modeling links experimental materials research integrated into a component or product using high-fidelity thermochemical and electrochemical models. The focus of this presentation will be on modeling method and results for H-SOEC electrolysis cells. The approach will facilitate material R&D in general and improve the computational tools to support industry for predicting product and life cycle performance. Validation of component performance and system integration results against prototype designs can allow iterative model improvement and enhance for various types, processes, and scales of systems.

Synergistic Coupling of Proton Conductors BaZr0.1Ce0.7Y0.1Yb0.1O3-δ and La2Ce2O7 to Create Chemical Stable, Interface Active Electrolyte for Steam Electrolysis Cells.

For the first time, proton conductors BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (BZCYYb) and La2Ce2O7 (LCO) are combined to create an interface active and steam-tolerant electrolyte for high-performance proton-conducting solid oxide electrolysis cells. LCO shows good chemical compatibility with BZCYYb. The readily fabricated LCO/BZCYYb bilayer electrolyte can be densified at a temperature of as low as 1300 °C versus ∼1600 °C for the benchmark steam-stable BaZr0.8Y0.2O3-δ electrolyte. With Pr2NiO4+δ as the anode and Ni as the cathode catalyst, this bilayer electrolyte cell yields a current density of 975 and 300 mA/cm2 under a 1.3 V applied potential at 700 and 600 °C, respectively. This performance is among the best of all H-SOECs equipped with a chemically stable electrolyte so far. A BZCYYb layer in the bilayer electrolyte promotes the hydrogen evolution reaction at the cathode side, resulting in a 108% improvement over the cellwithoutthis layer. The LCO layer, on the other hand, effectively protects this functional BZCYYb layer from the high concentration of steam in a practical SOEC operation condition. The cell without the LCO layer shows degradation in terms of an increased electrolyzing potential from 1.07 to 1.29 V during a constant 400 mA/cm2 operation at 700 °C. In contrast, the bilayer electrolyte cell maintains the same electrolyzing potential of 1.13 V under the same conduction for a 102 h operation. These findings demonstrate that this synergic bilayer electrolyte design is a vital strategy to overcome the dilemma between performance and stability faced by the current benchmark Zr- or Ce-rich Ba(CeZr)O3-δ electrolysis cells to achieve excellent performance and stability at the same time.