Solid Oxide Electrolysis Cells Research Articles

Numerical study on improved mass and heat transfer performance in a solid oxide electrolysis cell with sine wave flow field

In this paper, the periodic variation of sine wave is used to promote the transport and diffusion process of reactive gases; and the relationship between the performance of a solid oxide electrolysis cell (SOEC) and the mass and heat transfer capabilities of its flow field is thoroughly examined. The impact of variations in the amplitude and frequency of the sine wave on the SOEC's electrolysis efficiency, its mass and heat transfer properties, and fluid flow dynamics are explored. The results indicate that longitudinal flow velocity of the gas in the sine wave flow channel is increased by 26.96-80.76% at a current density of 10000 A/m2, and this kind of flow channel exhibits superior gas transport performance. Moreover, the temperature-uniformity index and the maximum thermal stress of the positive-electrolyte-negative (PEN) structure are decreases by 18.93-22.67% and 20%, respectively. It indicates that this configuration is capable of reducing thermal stress and enhancing the uniformity of temperature distribution at high current-densities. Increasing the amplitude and frequency improves the comprehensive performance of the flow field. More specifically, frequency has a greater impact on flow field performance than amplitude.

Bimetallic Ni-Fe Supported by Gadolinium Doped Ceria (GDC) Catalyst for CO2 Methanation

CO2 conversion into fuels and high value-added chemical feedstocks, such as methane, has gained novel interest as a crucial process for further manufacturing multi-carbon products. Methane, CH4, becomes a promising alternative for environmental and energy supply issues. Nickel-based catalysts were found to be very active and selective for CH4 production. The use of promoter and support material to develop high activity, high selectivity, and durable catalysts for CO2 methanation at low temperature is a challenge. Gadolinium-Doped Ceria (GDC) has been known as material for Solid Oxide Fuel Cell (SOFC) and Solid Oxide Electrolysis Cell (SOEC) due to higher ionic conductivity and lower operating temperatures. However, few researches have been done regarding to CO2 methanation over GDC as catalyst support so far. In this present work, CO2 methanation was investigated over bimetallic Ni-Fe catalyst supported by GDC. The results showed that CH4 production rate by using Ni-Fe/GDC catalyst was higher than that of GDC at all reaction temperatures carried on. Ni-Fe/GDC showed remarkable CH4 production rate as of 17.73 mmol.gcat−1.h−1 at 280 °C. No catalytic activity was produced by GDC catalyst only. The highest CO2 conversion (46.50%) was observed at 280 °C, with almost 100% selectivity to CH4. The turnover frequency (TOF) value of Ni-Fe/GDC (4529.32 h−1) was the highest than that of Ni and common CO2 methanation catalyst, Ni/Al2O3 catalysts at 280 °C, further displaying the outstanding low-temperature catalytic activity. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Scientometric analysis of research trends on solid oxide electrolysis cells for green hydrogen and syngas production

Scientometric analysis of research trends on solid oxide electrolysis cells for green hydrogen and syngas production

Dynamic Behavior of an SOEC System With a Schedule-Based Start-Up and Operating Process

Abstract The solid oxide electrolysis cell (SOEC) is recognized as a promising method for hydrogen production, attributed to its high efficiency. Steam is split into hydrogen and oxygen by electrolysis at high temperatures. Electrolysis is inherently an endothermic process; however, it can be transformed into an exothermic process depending on the operating voltage. During the start-up process, the heat reaction is observed to change from endothermic to exothermic around a thermoneutral voltage. In this study, a dynamic model of the solid oxide electrolyzer system was developed, and the behavior of the system during the start-up process was analyzed. A dynamic model of the stack was developed to investigate the behavior of cell temperature and current density. Furthermore, 1D models of heat exchangers and 0D models of blowers were developed and verified against experimental results. These components were systematically organized and simulated. The temperatures of the stack and components during a schedule-based start-up process were investigated. Additionally, the behavior during the load change process, shifting from an endothermic reaction to an exothermic reaction, was examined. It was found that to reach an operating condition above the thermoneutral voltage, additional heat is required for the stack due to its endothermic reaction. The effect of air on the stack was also found to be dependent on the operating voltage of the stack.

Optimally Splitting Solar Spectrums by Concentrating Solar Spectrums Splitter for Hydrogen Production via Solid Oxide Electrolysis Cell

The concentrating solar spectrums splitter (CSSS)-driven solid oxide electrolysis cell (SOEC) is an attractive technology for green hydrogen production. The CSSS mainly comprises a concentrating photovoltaic (CPV), which converts sunlight with shorter wavelengths into electricity, and a concentrating solar collector (CSC), which converts the remaining sunlight into heat. However, the optimal splitting of the solar spectrums is a critical challenge that directly impacts the efficiency and normal operation of the SOEC. To address this challenge, a mathematical model integrating the CSSS with the SOEC is developed based on principles from thermodynamics and electrochemistry. By analyzing the requirements of electricity and heat for the SOEC, the model determines the optimal configuration and operational parameters. The results show that the anode-supported type, higher operating temperature, larger inlet flow rate of water, higher operating pressure of the SOEC, higher operating temperature of the CSC, and larger electric current of the CPV contribute to allocating more solar spectrums to the CSC for heat generation. However, the greater effectiveness of the heat exchangers, higher operating temperature, and larger optical concentration ratio of the CPV exhibit contrasting effects on the spectrum allocation. The obtained results provide valuable theoretical guidance for designing and running the CSSS for hydrogen production through SOEC.

Effect of the operating temperature on the degradation of solid oxide electrolysis cells

The present work aims to better understand the effect of operating temperature on the degradation of Solid Oxide Electrolysis Cells (SOECs). The studied SOECs consist of La0.6Sr0.4Co0.2Fe0.8O3-δ-Ce0.8Gd0.2O2-δ (LSCF-GDC) oxygen electrode, GDC diffusion barrier layer, Y0.16Zr0.84O1.92 (YSZ) electrolyte and Ni-YSZ hydrogen electrode. Durability tests are carried out at 750, 800 and 850 °C for 2000 h at −1 A cm−2, using 10/90 vol% H2/H2O and dry air at the hydrogen and oxygen electrodes, respectively. The electrochemical impedance spectra measured before and after ageing reveal a strong evolution related to the hydrogen electrode, while the change in the oxygen electrode contribution remains negligible. A set of advanced characterization techniques are employed to study the cell degradation. For the hydrogen electrode, a large Ni depletion is observed after ageing, which increases with the operating temperature. The analysis of the oxygen electrode shows an elemental inter-diffusion between the LSCF-GDC/GDC/YSZ layers on the manufactured cells that seems to not evolve significantly upon operation. Moreover, the presence of SrZrO3 is not detected in the pristine cell and in the operated ones. Besides, only a limited LSCF decomposition is found in good agreement with the electrochemical characterizations. Hypotheses that could explain the good oxygen electrode stability are discussed.

Active Cu and Fe Nanoparticles Codecorated Ruddlesden–Popper‐Type Perovskite as Solid Oxide Electrolysis Cells Cathode for CO2 Splitting

Active Cu and Fe Nanoparticles Codecorated Ruddlesden–Popper‐Type Perovskite as Solid Oxide Electrolysis Cells Cathode for CO₂ Splitting

Syngas Production from CO2 and H2O via Solid-Oxide Electrolyzer Cells: Fundamentals, Materials, Degradation, Operating Conditions, and Applications.

Highly efficient coelectrolysis of CO2/H2O into syngas (a mixture of CO/H2), and subsequent syngas conversion to fuels and value-added chemicals, is one of the most promising alternatives to reach the corner of zero carbon strategy and renewable electricity storage. This research reviews the current state-of-the-art advancements in the coelectrolysis of CO2/H2O in solid oxide electrolyzer cells (SOECs) to produce the important syngas intermediate. The overviews of the latest research on the operating principles and thermodynamic and kinetic models are included for both oxygen-ion- and proton-conducting SOECs. The advanced materials that have recently been developed for both types of SOECs are summarized. It later elucidates the necessity and possibility of regulating the syngas ratios (H2:CO) via changing the operating conditions, including temperature, inlet gas composition, flow rate, applied voltage or current, and pressure. In addition, the sustainability and widespread application of SOEC technology for the conversion of syngas is highlighted. Finally, the challenges and the future research directions in this field are addressed. This review will appeal to scientists working on renewable-energy-conversion technologies, CO2 utilization, and SOEC applications. The implementation of the technologies introduced in this review offers solutions to climate change and renewable-power-storage problems.

Boosting the electrocatalytic activity of NdBaCo2O5+δ via calcium co-doping as bifunctional oxygen electrodes for reversible solid oxide cells

The oxygen electrode of the solid oxide cells (SOCs) operates under an oxidizing atmosphere. Lattice shrinkage in a high oxygen partial pressure environment results in cation misalignment, leading to a decline in performance. Addressing the drawbacks associated with A-site cation mismatch in LnBaCo2O5+δ double perovskite oxides for reversible solid oxide cells (RSOCs) oxygen electrodes, a novel calcium ion co-doping strategy is proposed. This approach effectively mitigates A-site cation segregation and enhances stability. The glycine-nitrate method was employed to synthesize Nd0.8Ca0.2Ba1−xCaxCo2O5+δ (x = 0–0.2) layered double perovskites oxides co-doped with calcium ions, denoted as NCBCC. NCBCC exhibits excellent compatibility with commonly used electrolytes. The doping of calcium co-doped in NdBaCo2O5+δ decreases the thermal expansion coefficient and improves the electron transfer characteristics. The sample with x = 0.1 exhibited an area-specific resistance (ASR) of 0.024 Ω cm2 when operated at a temperature of 800 °C in air. In the solid oxide fuel cell mode, employing x = 0.1 as an oxygen electrode, the maximum power density achieved was 766 mW cm−2 at 800 °C. In the solid oxide electrolysis cell mode, operating with CO2 and steam at an electrolysis voltage of 1.5 V and a temperature of 800 °C, the corresponding current densities were −1.51 and −1.85 A cm−2, respectively. The incorporation of calcium ions into layered perovskite oxides offers a promising strategy to enhance the performance of oxygen electrodes in RSOCs.

Predicting the Rate of Degradation Related to Oxygen Electrode Delamination in Solid Oxide-Ion Electrolyzers

One of the leading causes for the performance degradation in H2-producing solid oxide electrolytic cells (SOECs) is the gradual delamination of oxygen electrode (OE) from the electrolyte under a strong anodic polarization. Identification of the key factor that controls the rate of OE delamination is of paramount importance to achieve long-term stable operation of SOECs. Here we show from thousands of hours of testing data that the exchange current density (i°) of OE can be leveraged as a predictor for the rate of delamination. To obtain i°, we apply DC-biased electrochemical impedance spectroscopy on a three-electrode symmetrical cell to measure polarization resistance (Rp) of OE as a function of current density (i) and time (t). The collected Rp-i-t raw data are then converted to overpotential (η)-i-t, from which i° is extracted from the “low-field” approximation. An analytical relationship between i° and time-to-delamination (TTD) is further established from the established i°-i-t relationship. We show that under a constant anodic polarization current density i, the greater the ratio i/i°, the faster the delamination. Therefore, we conclude that the exchange current density of an OE, i°, can be used to predict the rate of OE degradation in solid oxide-ion electrolyzers.

Enhancing the steam electrolysis by simultaneously regulating the electron and oxygen ion conductivity of la1-xsr1+xfeo4-δ oxides

Ruddlesden-Popper (RP) La1-xSr1+xFeO4-δ(x = 0,0.2,0.4) oxides with different Sr content are investigated as air electrodes for solid oxide electrolytic cells. The increased Sr content in La1-xSr1+xFeO4-δ significantly improves the electronic and oxygen ionic conductivity, enhancing the oxygen evolution reaction (OER) activity and electrochemical performance of steam electrolysis. The polarization resistance of the La0.8Sr1.2FeO4-δ symmetrical cell reaches 1.04 Ω cm2 at 800 °C, and the electrolysis cell delivers a current density of −1709 mA cm−2 at 1.3 V, corresponding to the hydrogen production rates of 714 ml/(cm2 h). Moreover, adding Sm0.2Ce0.8O2-δ (SDC) oxide further improves the steam electrolysis performance due to enhanced three-phase boundary active sites. The electrolysis cell with La0.8Sr1.2FeO4-δ-SDC electrode exhibits excellent stability for over 200 h and cycling durability for 100 h under 750 °C and 1.2 V in 50%H2O–H2 condition.

An innovative perovskite oxide enabling improved efficiency for low-temperature ceramic electrochemical cells

In recent years, energy carriers for renewable sources and devices that convert chemical energy into electrical energy, such as solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs), have made hydrogen production economically viable and have numerous industrial uses. We have designed SrFe0.3TiO3 (SFT) materials to function as SOFC and H-SOEC electrolytes at low operational temperatures of 520–420 °C. The SFT (600 °C) shows a higher fuel cell power density of 650 mW/cm2 and a reasonable current density of 1.14 A/cm2 in fuel cell and electrolysis cell mode at 520 °C. The formation of the surface layer enables high ionic and Proton conduction due to a high number of oxygen vacancies, and the core–shell type interface enables easy and quick proton transportation restricted to the surface. Energy band alignment and distribution relaxation time (DRT) were also evaluated to study ion transport in SFT materials. These results open up advanced avenues for the design of high-performance, sophisticated proton-conducting electrolytes for ceramic electrochemical cells.

Dynamic response characteristics of solid oxide cell stacks for seawater/CO2 co-electrolysis under strong fluctuation electricity

This work focused on the intermittent characteristics of renewable energy and studied the dynamic response characteristics of seawater/CO2 co-electrolysis on solid oxide cell stacks to produce syngas under strong fluctuation electricity conditions. The results showed that when using a strong fluctuating current density of 58.2–658.1 mA/cm2 to simulate wind turbines, the power variation of the solid oxide cell stack was almost in line with the simulated wind turbine power variation curve. The theoretical conversion rate of solid oxide cell stack electrolysis products is linearly related to the current density. The measured H2O+CO2 conversion rate is similar to the theoretical value, and the current variation hardly changes the H2/CO ratio in the exhaust gas. Therefore, solid oxide electrolysis cell stacks have strong adaptability to fluctuating electricity.

Medium-entropy perovskite Pr0.4Ba0.2Ca0.2La0.2Co0.2Fe0.8O3 as a promising bifunctional electrocatalyst for electrochemical energy conversion device

Reversible solid oxide cells (R-SOCs) are considered to be a promising energy conversion device that can achieve efficient conversion between fuel and electrical energy. However, there are still significant challenges in developing a promising bifunctional electrocatalyst as an electrode material for R-SOC devices. Here, a medium-entropy perovskite Pr0.4Ba0.2Ca0.2La0.2Co0.2Fe0.8O3 (PBCLCF) is designed to enhance the electrochemical oxidation and reduction activity. Under hydrogen atmosphere, cobalt metals are in situ exsolved from the perovskite structure, accompanied by partial phase transformation (denoted as R-PBCLCF). Characterizations show that PBCLCF and R-PBCLCF can increase the concentration of oxygen vacancies, thereby enhancing oxygen migration ability. Combined with electrochemical impedance spectroscopy (EIS) and distribution of relaxation times (DRT) analysis, the medium-entropy PBCLCF exhibits better oxygen reduction reaction (ORR) activity and R-PBCLCF shows better hydrogen oxidation reaction (HOR) activity. Furthermore, the oxygen dissociation is identified as the rate-determining step (RDS) in the ORR process, whereas the HOR process is dominated by the hydrogen adsorption and dissociation. The single cell with (R-)PBCLCF showcases remarkable reversible performance. When O2 is employed as the oxidant and H2 as the fuel, this cell achieves a maximum power density of 468.1 mW cm−2 in solid oxide fuel cell (SOFC) mode at 700 °C. Moreover, when O2 is employed as the oxidant and humidified H2 (30 %H2O) as the fuel, the current density of the cell in solid oxide electrolysis cell (SOEC) mode is −647.3 mA cm−2 at 1.3 V and 700 °C.

Highly active and robust A-site deficient La0.77Sr0.2Co0.2Fe0.8O3-δ fiber base electrode for intermediate temperature solid oxide cells

The combination of solid oxide electrolysis cells (SOECs) and solid oxide fuel cells (SOFCs) is expected to solve the problems of energy conversion and storage. However, the insufficient catalytic capacity and poor durability of the oxygen electrodes in solid oxide cells (SOCs) at intermediate temperatures pose a huge challenge for SOCs applications. In this work, A-site deficient La0.77Sr0.2Co0.2Fe0.8O3-δ nanorod materials coated with Ce0.8Gd0.2O1.9 (GDC) are prepared to suppress cation surface segregation and enhance charge transfer kinetics by reducing internal elastic force of perovskite and meanwhile applying external compressive stress with an oxygen-ion conductor. As a result, the composite cathode with a GDC to La0.77Sr0.2Co0.2Fe0.8O3-δ weight ratio of 0.59 (La0.77Sr0.2Co0.2Fe0.8O3-δ@GDC0.59) exhibits excellent electrochemical performance and long-term stability when operating in both SOFCs and SOECs modes. XPS results show that the La0.77Sr0.2Co0.2Fe0.8O3-δ@GDC0.59 oxygen electrode exhibits no significant Sr/Fe surface segregation after operating in SOFCs and SOECs modes for 200 h. Density functional theory calculation and physiochemical characterization confirm that Sr segregation phenomenon is well inhibited through the novel A-site deficient structural design of perovskite materials, which eliminates the major residual internal elastic force of La0.8Sr0.2Co0.2Fe0.8O3-δ crystal, and GDC coating further relieves the lattice transformation of La0.77Sr0.2Co0.2Fe0.8O3-δ upon the additional introduction of A-site deficiency and oxygen vacancy. This well-orchestrated composite cathode design provides a new perspective in stabilizing perovskite crystalline structure toward high-performance SOCs with extended operating life.

Boosting the catalytic activity of high-order Ruddlesden–Popper perovskite SrEu2Fe2O7-δ air electrode by A-site La doping for CO2 electrolysis in solid oxide electrolysis cells

Ruddlesden–Popper (R-P) oxides (An+1BnO3n+1) are potential air electrodes for solid oxide electrolysis cells (SOECs) because of their good electrochemical performance. Among them, SrEu2Fe2O7-δ (SEF) with n = 2 has received extensive attention because of its special structure and promising ionic–electronic conductivity. However, the SEF material is prone to degradation at high temperatures (600 °C–800 °C), and its long-term stability is easily affected. In this study, R-P oxide Sr1-xLaxEu2Fe2O7-δ (SLEFx; x = 0, 0.05, 0.1) was successfully synthesized using the sol–gel method. XRD results showed that La-doped SEF displayed good chemical and thermal compatibility with the gadolinia-doped ceria electrolyte. The SLEF0.05 electrode exhibited a polarization resistance of 0.075 Ω cm2 at 800 °C, which was 88.2 % lower than that of SEF. The half-cell based on the SLEF0.05 air electrode exhibited improved performance under the long-term stability test at a current density of − 0.5 A cm−2 for over 110 h at 800 °C, indicating excellent stability. Moreover, an electrolysis current density as high as 0.712 A cm−2 at 1.5 V was obtained for the full cell with the SLEF0.05 air electrode, which was 45.8 % higher than the SEF electrode when the temperature and feed gas were 800 °C and 50 % CO2–50 % CO, respectively. The XPS and cell testing results confirmed that La with high valance and small radius promoted the formation of oxygen vacancies and effectively enhanced the electrochemical performance and structural stability of the SEF material. Therefore, the R-P oxide SLEF0.05 is a promising air electrode material for SOECs.

Self-optimized and stable nanocomposites via one-pot synthesis for high-temperature CO2 electrolysis in solid oxide electrolysis cells

Solid oxide electrolysis cells (SOECs) hold the promise of directly converting CO2 into CO fuels with exceptional cost-effectiveness and efficiency. However, the widespread application of SOECs is impeded by the significant lack of highly active and stable cathodes. Herein, a one-pot synthesis strategy is proposed to introduce Cu into a composite consisted of Sr2Fe1.5Mo0.5O6−δ (SFM) and Gd0.2Ce0.8O1.9 (GDC). This strategy leads to the automatic formation of hetero-structured composites, comprising double perovskite, Ruddlesden-Popper perovskite, fluorite, as well as in-situ exsolved Cu–Fe bimetals at high temperatures and operational conditions. Consequently, this approach greatly enhances CO2 adsorption capability, CO2 catalytic activity, O2−/e− conductivity, and ensures good phase compatibility with electrolyte. As results, the La0.8Sr0.2Ga0.8Mg0.2O3−δ electrolyte-supported single cell with the composite cathode achieves a high current density of 2.22 A cm−2 at 850 °C and 1.6 V, which is substantial increase of 65.7% compared to the current density achieved with traditional physically hybrid SFM-GDC cathodes. These results underscore the potential of one-pot synthesized nanocomposites as promising cathodes for CO2 electrolysis in SOECs.

Electrochemical characterization of electrolyte supported solid oxide electrolysis cell during CO2/H2O co-electrolysis

Electrochemical characterization of electrolyte supported solid oxide electrolysis cell during CO2/H2O co-electrolysis

Carbon dioxide reduction in solid oxide electrolyzer cells utilizing nickel bimetallic alloys infiltrated into Gd0.1Ce0.9O1.95 (GDC10) scaffolds

This study evaluates the electrochemical performance of Gd0.1Ce0.9O1.95 (GDC10) cathodes infiltrated with bimetallic Ni-Co and Ni-Cu alloy electrocatalysts for CO2 electroreduction in solid oxide electrolyzer cells (SOECs). The electrochemical reduction performance of SOECs with cathodes infiltrated with Ni-Co and Ni-Cu alloys was compared to the performance of SOECs having cathodes infiltrated with Ni, Co, and Cu. Electrochemical performance was evaluated at 750, 800, and 850 °C. Cells with Co, Ni0.50Co0.50, Ni0.75Co0.25, and Ni infiltrated cathodes displayed relatively similar CO2 electroreduction performance; however, SOECs having Co infiltrated cathodes had slightly better catalytic performance towards CO2 reduction as demonstrated by their lower polarization resistance (Rp) values of 8.54, 4.03, and 1.25 Ω·cm2 when measured under open circuit voltage (OCV) at 750, 800, and 850 °C, respectively. Cells having Co, Ni0.50Co0.50, Ni0.75Co0.25, and Ni infiltrated cathodes showed a stable long-term CO2 electroreduction performance with Faradaic efficiency values approaching 100 % when tested under 0.20 A·cm−2 for 48 h and at 750 °C. Results indicate that SOECs with Ni infiltrated cathodes possessed better short- and long-term CO2 electroreduction performance compared to SOECs featuring cathodes infiltrated with Cu, Ni0.25Cu0.75, and Ni0.50Cu0.50. Increasing Ni percentage within the Ni-Cu alloy structure had a positive impact on the electrochemical performance as cells with Ni0.50Cu0.50 infiltrated cathodes showed relatively close voltage values to those of cells with Ni infiltrated cathodes during short-term galvanostatic tests. Although the SOEC with Ni0.50Cu0.50 infiltrated cathode experienced performance degradation throughout the long-term test period, it demonstrated better electroreduction performance having Faradaic efficiency values approaching 100 % compared to cells with Cu and Ni0.25Cu0.75 infiltrated cathodes when evaluated under 0.20 A·cm−2 for 48 h and at 750 °C.

Controllable Technology for Thermal Expansion Coefficient of Commercial Materials for Solid Oxide Electrolytic Cells.

Solid oxide electrolysis cell (SOEC) industrialization has been developing for many years. Commercial materials such as 8 mol% Y2O3-stabilized zirconia (YSZ), Gd0.1Ce0.9O1.95 (GDC), La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF), La0.6Sr0.4CoO3-δ (LSC), etc., have been used for many years, but the problem of mismatched thermal expansion coefficients of various materials between cells has not been fundamentally solved, which affects the lifetime of SOECs and restricts their industry development. Currently, various solutions have been reported, such as element doping, manufacturing defects, and introducing negative thermal expansion coefficient materials. To promote the development of the SOEC industry, a direct treatment method for commercial materials-quenching and doping-is reported to achieve the controllable preparation of the thermal expansion coefficient of commercial materials. The quenching process only involves the micro-treatment of raw materials and does not have any negative impact on preparation processes such as powder slurry and sintering. It is a simple, low-cost, and universal research strategy to achieve the controllable preparation of the thermal expansion coefficient of the commercial material La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) through a quenching process by doping elements and increasing oxygen vacancies in the material. Commercial LSCF materials are heated to 800 °C in a muffle furnace, quickly removed, and cooled and quenched in 3.4 mol/L of prepared Y(NO3)3. The thermal expansion coefficient of the treated material can be reduced to 13.6 × 10-6 K-1, and the blank sample is 14.1 × 10-6 K-1. In the future, it may be possible to use the quenching process to select appropriate doping elements in order to achieve similar thermal expansion coefficients in SOECs.