Metal support type solid oxide electrolysis cell substrate and process for making same

Abstract

The application belongs to the technical field of solid oxide electrolysis cell, and particularly relates to a metal-supported solid oxide electrolysis cell substrate and a preparation process thereof. The metal-supported solid oxide electrolysis cell substrate comprises a gradient-pore metal support layer as a bottom layer, an LSM / YSZ composite transition layer in the middle, and a dense ScSZ or GDC electrolyte layer as a top layer. In the preparation process, first, a metal slurry with different pore-forming agent contents is synchronously cast by double-casting heads to form a gradient-pore structure of the metal support layer, then the transition layer and the electrolyte layer are sequentially cast, and finally, the substrate is sintered in sections. By means of the gradient-pore design, low-temperature sintering in sections and in-situ interface protection layer technology, high mechanical strength and excellent gas permeability are simultaneously achieved, and the interface resistance is reduced to 0.08 Omega cm 2 Below, the current density reaches 1.25 A / cm 2 at 750 DEG C working temperature, and the performance and service life of the electrolysis cell are significantly improved.

Description

Technical Field

[0001] This invention belongs to the field of solid oxide electrolyzer technology, and is particularly applicable to renewable energy conversion systems such as high-temperature water electrolysis for hydrogen production and carbon dioxide co-electrolysis. Specifically, it relates to a metal-supported solid oxide electrolyzer substrate and its preparation process. Background Technology

[0002] Solid oxide electrolyzers (SOECs), as highly efficient devices that convert electrical energy into chemical energy, have shown great application potential in the energy sector. SOECs can operate at high temperatures and produce clean energy sources such as hydrogen or carbon monoxide through the electrolysis of water or carbon dioxide, providing an important pathway to achieving sustainable energy development.

[0003] Traditional SOECs typically use ceramic materials as supports. However, ceramic materials have drawbacks such as poor thermal shock resistance and difficulty in large-area scaling and integration, limiting the large-scale application of SOECs. Metal-supported SOECs (MS-SOECs) have emerged to address this limitation. Using metal materials as supports, they possess excellent thermal conductivity, mechanical strength, and thermal shock resistance. This effectively reduces mechanical and thermal stresses on the battery during service, improving battery life and stability. It also facilitates large-area scaling and stacking of batteries, thereby improving energy conversion efficiency and reducing costs.

[0004] However, existing MS-SOEC technology still has the following bottlenecks: Poor interface compatibility: During high-temperature sintering, elemental interdiffusion occurs between the metal support (such as Fe, Cr) and the ceramic electrode / electrolyte layer (such as Ni-YSZ, ScSZ), leading to an increase in interfacial resistance (>0.35 Ω·cm). 2 ) and performance degradation (>5% / thousand hours); High process complexity: Traditional split-type brazing (such as CN114597424A) or multi-layer spraying process requires multiple high-temperature treatments, resulting in low yield and high cost. Porosity versus strength: The support needs high porosity (>30%) to ensure gas permeability, but this will sacrifice mechanical strength (<30 MPa).

[0005] To address the above problems, existing technologies have proposed some improvement solutions, but all of them have limitations: The patent application with publication number CN113161566A uses metal wire mesh stacking and sintering, which improves strength, but the porosity is uncontrollable and the gas mass transfer efficiency is low. The patent application with application number CN202210356489.0 prepares a GDC / ScSZ composite electrolyte layer by magnetron sputtering to suppress electron leakage, but the process equipment is expensive and difficult to scale up. The patent application CN119019183A filed by Shandong Industrial Ceramics Research Institute proposes a layered sintering process, but residual pore-forming agent affects long-term stability.

[0006] In summary, developing a metal-supported SOEC substrate process that combines high interface stability, low-cost fabrication, and gradient porosity optimization is key to overcoming existing technological barriers. Summary of the Invention

[0007] To overcome the shortcomings of the prior art, the present invention provides a metal-supported solid oxide electrolytic cell substrate and its preparation process. The present invention solves the problems of poor interface compatibility, complex process, and difficulty in balancing porosity and strength of traditional metal-supported SOEC substrates by using gradient pore structure design, low-temperature segmented sintering process and in-situ interface protection layer technology.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first aspect of this invention provides a metal-supported solid oxide electrolyzer substrate, comprising a gradient porosity metal support layer, a transition layer, and a dense electrolyte layer; the gradient porosity metal support layer comprises a bottom layer and a top layer, the bottom layer having a porosity of 10-15% and the top layer having a porosity of 35-40%, and the gradient porosity metal support layer being an Fe-Cr based alloy material; the transition layer is disposed on the gradient porosity metal support layer and is composed of La... 0.8 Sr 0.2 The composite of MnO3 and yttrium-stabilized zirconium oxide; the dense electrolyte layer is disposed on the transition layer and is composed of scandium oxide-stabilized zirconium oxide or gadolinium oxide-doped cerium oxide.

[0009] Preferably, the bottom layer thickness of the gradient porosity metal support layer is 400-500 μm, and the top layer thickness is 400-500 μm. The porous metal support layer has a flexural strength greater than 50 MPa and a gas permeability greater than 1 × 10⁻⁶. -12 m 2 .

[0010] Preferably, the thickness of the transition layer is 20-40 μm, and the porosity of the transition layer is 20-25%.

[0011] Preferably, La in the transition layer 0.8 Sr 0.2 The mass ratio of MnO3 to yttrium oxide-stabilized zirconium oxide is 1-1.2:1.

[0012] Preferably, the thickness of the dense electrolyte layer is 10-15 μm, and the porosity of the dense electrolyte layer is less than 3%.

[0013] A second aspect of the present invention provides a fabrication process for the above-mentioned metal-supported solid oxide electrolytic cell substrate, the fabrication process comprising the following steps: (1) Prepare the bottom layer slurry, top layer slurry, and transition layer slurry of the metal support layer separately; (2) The bottom layer slurry and the top layer slurry are simultaneously cast using a dual casting head to form a metal support layer with a gradient pore structure. The transition layer and the electrolyte layer are then cast sequentially on the surface of the metal layer. (3) Perform lamination and pre-sintering; (4) Degreasing and densification are carried out by segmented sintering to obtain a metal-supported solid oxide electrolytic cell substrate.

[0014] Preferably, the bottom slurry of the metal support layer comprises 85 wt% Fe-Cr alloy powder, 10 wt% starch pore-forming agent, and 5 wt% polyvinyl alcohol binder, and the top slurry of the metal support layer comprises 65 wt% Fe-22Cr alloy powder, 30 wt% starch pore-forming agent, and 5 wt% polyvinyl alcohol binder. The viscosity of the bottom and top slurries of the metal support layer is 2000-5000 mPa·s.

[0015] Preferably, the transition layer slurry comprises La 0.8 Sr 0.2 MnO3, yttrium oxide stabilized zirconium oxide, ethyl cellulose and glycerol.

[0016] Preferably, the lamination pressure is 10-20 MPa and the lamination temperature is 80°C.

[0017] Preferably, the pre-sintering refers to removing the organic binder by holding the mixture at 500°C for 2 hours in an Ar atmosphere.

[0018] Preferably, the segmented sintering refers to: the first stage being held at 800-900℃ for 1 hour in an H2 / N2 mixed atmosphere with 5% H2; and the second stage being held at 1000-1100℃ for 4 hours in an H2 / Ar mixed atmosphere with 2-3% H2.

[0019] Preferably, the heating rate in the first stage is 2°C / min.

[0020] During sintering, the transition layer reacts with the metal support layer to form a La-Cr-O spinel phase with a thickness of less than 1 μm and an interfacial resistivity of less than 0.1 Ω·cm. 2 .

[0021] A third aspect of the present invention provides a solid oxide electrolytic cell, the solid oxide electrolytic cell comprising the above-described metal-supported solid oxide electrolytic cell substrate.

[0022] Compared with the prior art, the beneficial effects of the present invention are: This invention achieves both high mechanical strength (flexural strength > 50 MPa) and high gas permeability (> 1 × 10⁻⁶) through a gradient pore structure design. -12 m 2 This technology resolves the contradiction between traditional substrate strength and mass transfer efficiency; employing a low-temperature segmented sintering process, the maximum sintering temperature is reduced to 1100℃, significantly suppressing metal oxidation and interfacial element diffusion; the in-situ generated La-Cr-O spinel interface layer effectively blocks Cr element diffusion, reducing the interface resistance to 0.08Ω·cm. 2 The integrated casting process simplifies the manufacturing process, reducing the number of steps from the traditional 7 to 4, and lowering production costs by 40%. At an operating temperature of 750℃, the current density reaches 1.25 A / cm². 2 Compared to traditional substrates (0.9A / cm), 2 The lifespan is increased by 38% and extended to over 20,000 hours (attenuation rate <3% / thousand hours). Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the metal-supported solid oxide electrolytic cell substrate of the present invention. Detailed Implementation

[0024] The specific embodiments of the present invention will be further described below. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0025] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, and the experimental materials used in the following embodiments are all available through conventional commercial channels.

[0026] Example 1 Fabrication and Testing of Metal-Supported Solid Oxide Electrolytic Cell Substrates 1. Preparation (1) Mix 85wt% Fe-22Cr alloy powder (particle size 5-20μm), 10wt% starch (bottom layer), and 5wt% PVA, and ball mill for 24 hours (200rpm), controlling the slurry viscosity to 3000mPa·s (25℃) to obtain the bottom layer slurry of the metal support layer; mix 65wt% Fe-22Cr alloy powder (particle size 5-20μm), 30wt% starch (bottom layer), and 5wt% PVA, and ball mill for 24 hours (200rpm), controlling the slurry viscosity to 3000mPa·s (25℃) to obtain the top layer slurry of the metal support layer; according to LSM (La 0.8 Sr 0.2 MnO3:YSZ (yttrium oxide stabilized zirconium oxide) mass ratio = 1:1 (solid content 45%), with the addition of 8wt% ethyl cellulose and 2wt% glycerol to obtain the transition layer slurry; (2) The bottom layer slurry and the top layer slurry with a thickness of 500 μm were simultaneously cast using a dual casting head to obtain the bottom layer and the top layer of the metal support layer. Then, a transition layer with a thickness of 30 μm and a dense electrolyte layer with a thickness of 15 μm (scandium oxide stabilized zirconia ScSZ, Sc2O3 content 8 mol%) were cast sequentially on the surface of the metal support layer. (3) Lamination was performed for 10 minutes under a pressure of 15 MPa and a temperature of 80 °C, and then the organic binder was removed by heating to 500 °C at a rate of 3 °C / min in an Ar atmosphere and holding for 2 hours. (4) In a mixed atmosphere of H2 / N2 with a H2 content of 5%, the temperature is raised to 800-900℃ at a rate of 2℃ / min and held for 1 hour; then in a mixed atmosphere of H2 / Ar with a H2 content of 2%, the temperature is rapidly raised to 1100℃ and held for 4 hours, and then cooled to room temperature at a rate of 5℃ / min to obtain a metal-supported solid oxide electrolytic cell substrate.

[0027] 2. Testing Porosity testing: Dual verification was performed using ASTM D4404-18 (mercury porosimetry) and ASTM C20-00 (Archimedes method). Samples were cut into 10×10×2 mm cubes, dried at 110 ℃ for 2 h, and tested using a Micromeritics AutoPore IV 9520 mercury porosimetry instrument. Pressure range: 0.1-414 MPa, contact angle: 130°, mercury surface tension: 485 mN / m, pore size distribution (5 nm-500 μm) was measured. Archimedes method verification was performed using a precision electronic balance (accuracy 0.1 mg), with anhydrous ethanol (density 0.789 g / cm³). 3 ), Calculation formula: Where Wdry is dry weight, Wasat is saturated weight, and Wimm is suspended weight.

[0028] Bending strength test: Following ISO 14704:2016 (three-point bending method for fine ceramics), an Instron 5967 universal testing machine and a high-temperature environmental chamber were used. Sample size: 3×4×40 mm (polished to Ra ≤0.2μm), span: 30 mm, loading rate: 0.5 mm / min, test temperature: 25 ℃ (room temperature) and 750 ℃ ​​(high temperature). Calculation formula: Where F is the fracture load, L is the span, b is the width, and h is the thickness.

[0029] Interfacial resistance testing: Following IEC 62391-1 (AC impedance spectroscopy for solid oxide cells), a Hezhiyuan SOFC single-cell test bench and a DH7002A-1 electrochemical workstation were used. Working electrode: Pt slurry coated with a transition layer (area 1 cm²). 2 Counter / reference electrode: symmetrical Pt ring, frequency range: 0.1 Hz-1 MHz, amplitude: 10 mV, temperature: 750 ℃ ​​(H2 / 3%H2O atmosphere), equivalent circuit fitted using ZView software. The interface resistance is taken as the charge transfer resistance R. ct .

[0030] Current density testing: A Hezhiyuan SOFC single-cell test bench and a DH7002A-1 electrochemical workstation were used. The gas composition on the anode side was 97% H2 / 3% H2O, and the gas composition on the cathode side was air. The flow rate on the anode side was 100 ml / min, and the flow rate on the cathode side was 200 ml / min. The pressure on both the anode and cathode sides was atmospheric pressure. The temperature was increased to 750 ℃ ​​at a rate of 3~5 ℃ / min and stabilized for 1 h. The constant potential mode was used for scanning: 0.8V→1.2V (step size 0.05 V, each step held for 10 min). The steady-state current value (fluctuation <2%) was recorded. Each set of data was repeated for ≥3 samples, and outliers were removed.

[0031] According to the above testing method, the following results were obtained in this embodiment: Porosity: 12% for the bottom layer of the metal support layer and 38% for the top layer of the metal support layer; Flexural strength: 55 MPa; Interface resistance: 0.08Ω·cm 2 ; Current density at 750℃: 1.25 A / cm² 2 .

[0032] Example 2 Fabrication and Testing of Metal-Supported Solid Oxide Electrolytic Cell Substrates 1. Preparation (1) Mix 85wt% Fe-22Cr alloy powder (particle size 5-20μm), 10wt% starch (bottom layer), and 5wt% PVA, and ball mill for 24 hours (200rpm), controlling the slurry viscosity to 4000mPa·s (25℃) to obtain the bottom layer slurry of the metal support layer; mix 65wt% Fe-22Cr alloy powder (particle size 5-20μm), 30wt% starch (bottom layer), and 5wt% PVA, and ball mill for 24 hours (200rpm), controlling the slurry viscosity to 4000mPa·s (25℃) to obtain the top layer slurry of the metal support layer; according to LSM (La 0.8 Sr 0.2 MnO3:YSZ (yttrium oxide stabilized zirconium oxide) mass ratio = 1.2:1 (solid content 45%), with the addition of 8wt% ethyl cellulose and 2wt% glycerol to obtain the transition layer slurry; (2) The bottom layer slurry and the top layer slurry with a thickness of 500 μm were simultaneously cast using a dual casting head to obtain the bottom layer and the top layer of the metal support layer. Then, a transition layer with a thickness of 30 μm and a dense electrolyte layer with a thickness of 15 μm (scandium oxide stabilized zirconia ScSZ, Sc2O3 content 8 mol%) were cast sequentially on the surface of the metal support layer. (3) Lamination was performed for 10 minutes under a pressure of 15 MPa and a temperature of 80 °C, and then the organic binder was removed by heating to 500 °C at a rate of 3 °C / min in an Ar atmosphere and holding for 2 hours. (4) In a mixed atmosphere of H2 / N2 with a H2 content of 5%, the temperature is raised to 850℃ at a rate of 2℃ / min and held for 1 hour; then in a mixed atmosphere of H2 / Ar with a H2 content of 3%, the temperature is rapidly raised to 1050℃ and held for 4 hours, and then cooled to room temperature at a rate of 5℃ / min to obtain a metal-supported solid oxide electrolytic cell substrate.

[0033] 2. Testing According to the test method in Example 1, the following results were obtained in this example: Porosity: 14% for the bottom layer of the metal support layer and 36% for the top layer of the metal support layer; Flexural strength: 58 MPa; Interface resistance: 0.07 Ω·cm 2 ; Current density at 750℃: 1.30 A / cm² 2 .

[0034] Example 3 Fabrication and Testing of Metal-Supported Solid Oxide Electrolytic Cell Substrates 1. Preparation (1) Mix 85wt% Fe-16Cr alloy powder (particle size 5-30μm), 10wt% starch (bottom layer), and 5wt% PVA, and ball mill for 24 hours (200rpm), controlling the slurry viscosity to 3000mPa·s (25℃) to obtain the bottom layer slurry of the metal support layer; mix 65wt% Fe-22Cr alloy powder (particle size 5-20μm), 30wt% starch (bottom layer), and 5wt% PVA, and ball mill for 24 hours (200rpm), controlling the slurry viscosity to 3000mPa·s (25℃) to obtain the top layer slurry of the metal support layer; according to LSM (La 0.8 Sr 0.2 MnO3:YSZ (yttrium oxide stabilized zirconium oxide) mass ratio = 1:1 (solid content 45%), with the addition of 8wt% ethyl cellulose and 2wt% glycerol to obtain the transition layer slurry; (2) The bottom layer paste and the top layer paste are simultaneously cast using a dual casting head to obtain a metal support layer with a thickness of 500 μm. Then, a transition layer with a thickness of 40 μm and a dense electrolyte layer (gadolinium oxide-doped cerium oxide GDC) with a thickness of 15 μm are sequentially cast on the surface of the metal support layer. (3) Lamination was performed for 10 minutes under a pressure of 15 MPa and a temperature of 80 °C, and then the organic binder was removed by heating to 500 °C at a rate of 3 °C / min in an Ar atmosphere and holding for 2 hours. (4) In a H2 / N2 mixed atmosphere with H2 content of 5%, the temperature is raised to 800-900℃ at a rate of 2℃ / min and held for 1 hour; then in a H2 / Ar mixed atmosphere with H2 content of 3%, the temperature is rapidly raised to 1000℃ and held for 4 hours, and then cooled to room temperature at a rate of 5℃ / min to obtain a metal-supported solid oxide electrolytic cell substrate.

[0035] 2. Testing According to the test method in Example 1, the following results were obtained in this example: Porosity: 15% for the bottom layer of the metal support layer and 35% for the top layer of the metal support layer; Flexural strength: 50 MPa; Interface resistance: 0.10 Ω·cm 2 ; Current density at 700℃: 1.15 A / cm 2 .

[0036] Comparative Example 1 The substrate was prepared using the metal mesh lamination process described in Example 1 of the patent application with publication number CN113161566A.

[0037] Following the test method in Example 1, the test data for this comparative example were obtained as follows: Flexural strength: 30 MPa; Interface resistance: 0.35Ω·cm 2 ; Current density at 750℃: 0.90 A / cm³ 2 .

[0038] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A fabrication process for a metal-supported solid oxide electrolytic cell substrate, characterized in that, The preparation process includes the following steps: (1) Prepare the bottom layer slurry, top layer slurry, and transition layer slurry of the metal support layer separately; (2) The bottom layer slurry and the top layer slurry are simultaneously cast using a dual casting head to form a gradient porous metal support layer. A transition layer and a dense electrolyte layer are then cast sequentially on the surface of the gradient porous metal support layer. (3) Perform lamination and pre-sintering; (4) Degreasing and densification are carried out by segmented sintering to obtain a metal-supported solid oxide electrolytic cell substrate; The bottom layer of the metal support layer has a porosity of 10-15%, and the top layer has a porosity of 35-40%. The metal support layer is an Fe-Cr alloy material. The segmented sintering refers to: the first stage being held at 800-900℃ for 1 hour in an H2 / N2 mixed atmosphere with 5% H2; and the second stage being held at 1000-1100℃ for 4 hours in an H2 / Ar mixed atmosphere with 2-3% H2. The transition layer is composed of La 0.8 Sr 0.2 It is composed of MnO3 and yttrium oxide stabilized zirconium oxide; The dense electrolyte layer is composed of scandium oxide-stabilized zirconium oxide or gadolinium oxide-doped cerium oxide.

2. The fabrication process of a metal-supported solid oxide electrolytic cell substrate according to claim 1, characterized in that, The bottom slurry of the metal support layer comprises 85 wt% Fe-Cr alloy powder, 10 wt% starch pore-forming agent and 5 wt% polyvinyl alcohol binder, and the top slurry of the metal support layer comprises 65 wt% Fe-22Cr alloy powder, 30 wt% starch pore-forming agent and 5 wt% polyvinyl alcohol binder.

3. The fabrication process of a metal-supported solid oxide electrolytic cell substrate according to claim 1, characterized in that, The transition layer slurry includes La 0.8 Sr 0.2 MnO3, yttrium oxide stabilized zirconium oxide, ethyl cellulose and glycerol.

4. A metal-supported solid oxide electrolytic cell substrate prepared by the preparation process according to any one of claims 1-3.

5. The metal-supported solid oxide electrolytic cell substrate according to claim 4, characterized in that, The bottom layer of the gradient porous metal support layer has a thickness of 400-500 μm, and the top layer of the gradient porous metal support layer has a thickness of 400-500 μm.

6. The metal-supported solid oxide electrolytic cell substrate according to claim 4, characterized in that, The thickness of the transition layer is 20-40 μm.

7. The metal-supported solid oxide electrolytic cell substrate according to claim 4, characterized in that, La in the transition layer 0.8 Sr 0.2 The mass ratio of MnO3 to yttrium oxide-stabilized zirconium oxide is 1-1.2:

1.

8. The metal-supported solid oxide electrolytic cell substrate according to claim 4, characterized in that, The thickness of the dense electrolyte layer is 10-15 μm.

9. A solid oxide electrolytic cell, characterized in that, The solid oxide electrolytic cell includes the metal-supported solid oxide electrolytic cell substrate as described in claim 4.

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