Solid oxide electrolytic cell sealing material containing rare earth and preparation method thereof

Abstract

The invention discloses a rare earth-containing solid oxide electrolytic cell sealing material and a preparation method thereof, and relates to the field of solid oxide electrolytic cells. A predetermined mass ratio range of a rare earth oxide and a glass ceramic system is set; according to the preset mass ratio range of the rare earth oxide and the glass ceramic system, the rare earth oxide and the glass ceramic system with the mass meeting the requirements are taken; adding rare earth oxide into the glass ceramic system, and uniformly mixing to obtain a mixture; carrying out high-temperature melting and rapid water cooling on the mixture to obtain glass fibers; the glass fiber and the special solvent are uniformly mixed according to a preset proportion and defoamed, and then screen printing is performed to obtain the sealing material with a specific shape. The thermal expansion coefficient and the chemical stability are regulated and controlled by introducing the rare earth oxide, so that the sealing material can meet the strict running environment of SOEC (Solid Oxide Electrochemical Compression) with high temperature and high water vapor partial pressure, and the problem of air tightness failure caused by ion migration and hydration corrosion of a traditional sealing material containing alkali or alkaline earth metal is solved.

Description

Technical Field

[0001] The present invention relates to the field of solid oxide electrolytic cells, and more particularly, to a rare earth-containing solid oxide electrolytic cell sealing material and a preparation method thereof. Background Art

[0002] Solid oxide electrolytic cells (SOECs) can efficiently convert renewable energy electricity into hydrogen or syngas, facilitating energy storage and carbon neutrality. Flat-plate SOECs make full use of space and can output high voltage and high power, but a sealant is required to separate fuel and oxidant gases to ensure the normal operation of SOECs. However, the operating conditions of SOECs are more demanding, and in order to meet the commercial application requirements of SOECs, it is necessary to develop a sealing material that maintains chemical stability and has good sealing during long-term operation in a wet reducing atmosphere.

[0003] The alkali-free / alkaline-earth sealing system CaO-MgO-Al2O3-SiO2 is an ideal SOEC sealing system, which is not easily reacted with water vapor to form volatile hydroxides. However, its main crystalline phase, diopside, is a stable loose structure, and a glass modifier needs to be added to improve its TEC, reduce its viscosity, and enhance its resistance to water vapor corrosion. In the prior art, the softening temperatures of glass ceramics incorporating modifiers such as BaO, B2O3, and Y2O3 are in the range of 850 - 1000 °C, and the sintering temperature is too high; the softening temperatures of those incorporating alkali metal oxides such as Na2O and K2O are in the range of 500 - 800 °C, but they will undergo hydration corrosion under high water vapor partial pressure (>50% H2O), resulting in the failure of airtightness. Summary of the Invention

[0004] The present invention provides a rare earth-containing solid oxide electrolytic cell sealing material and a preparation method thereof to overcome at least one technical problem existing in the prior art.

[0005] On the one hand, an embodiment of the present invention provides a preparation method of a rare earth-containing solid oxide electrolytic cell sealing material, comprising:

[0006] Setting a predetermined mass ratio range of rare earth oxides and a glass ceramic system;

[0007] Taking rare earth oxides and a glass ceramic system with masses meeting the requirements according to the predetermined mass ratio range of the rare earth oxides and the glass ceramic system;

[0008] Adding the rare earth oxides into the glass ceramic system and mixing evenly to obtain a mixture;

[0009] After subjecting the mixture to high-temperature melting and rapid water cooling, glass fibers are obtained;

[0010] After uniformly mixing the glass fiber and the special solvent in a predetermined ratio and degassing, screen printing is carried out to obtain a sealing material with a specific shape.

[0011] Optionally, the mass ratio of the rare earth oxide to the glass-ceramic system ranges from 1% to 20%.

[0012] Optionally, the predetermined ratio of the glass fiber to the special solvent is 1:1.

[0013] Optionally, the predetermined ratio of the glass fiber to the special solvent is 1.5:1.

[0014] Optionally, the predetermined ratio of the glass fiber to the special solvent is 2:1.

[0015] Optionally, the special solvent includes a first solvent, a binder, a dispersant, and a plasticizer.

[0016] Optionally, the ratio of the first solvent, the binder, the dispersant, and the plasticizer is 62:1:6:5.

[0017] Optionally, the rare earth oxide includes one or more of La2O3, Sm2O3, CeO2, Nd2O3, Gd2O3, and Y2O3.

[0018] On the other hand, the present invention also provides a rare earth-containing solid oxide electrolyzer sealing material, comprising components: glass fiber and a special solvent; wherein,

[0019] The glass fiber includes a rare earth oxide and a glass-ceramic system.

[0020] Optionally, the rare earth oxide includes one or more of La2O3, Sm2O3, CeO2, Nd2O3, Gd2O3, and Y2O3.

[0021] The innovation points of the embodiments of the present invention include:

[0022] In this embodiment, by introducing rare earth oxides (such as CeO2, Y2O3), the thermal expansion coefficient (8 - 11 ppm / °C) and chemical stability are regulated, so that it can meet the harsh operating environment of high temperature (700 - 900 °C) and high water vapor partial pressure (>50% H2O) of SOEC, and solve the airtightness failure problem caused by ion migration and hydration corrosion of traditional sealing materials containing alkali (Na+ / K+) or alkaline earth metals (Ba 2 +). At the same time, preparing the glass-ceramic powder into a sealing material and applying it to the solid oxide electrolyzer is one of the innovation points of the embodiments of the present invention. Description of the Drawings

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0024] Figure 1 It is a flowchart of the preparation method provided by the embodiment of the present invention. Detailed implementation manners

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0026] It should be noted that the terms "include" and "have" and any variations thereof in the embodiments of the present invention and the drawings are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally further include steps or units not listed, or may optionally further include other steps or units inherent to these processes, methods, products, or devices.

[0027] The embodiment of the present invention discloses a rare earth-containing solid oxide electrolytic cell sealing material and a preparation method thereof. The following will be described in detail respectively.

[0028] Figure 1 It is a flowchart of the preparation method provided by the embodiment of the present invention. Please refer to Figure 1 The preparation method of the rare earth-containing solid oxide electrolytic cell sealing material provided by the embodiment of the present invention includes:

[0029] Step 1: Set the predetermined mass ratio range of rare earth oxides and the glass-ceramic system;

[0030] Step 2: According to the predetermined mass ratio range of rare earth oxides and the glass-ceramic system, take rare earth oxides and the glass-ceramic system with masses meeting the requirements;

[0031] Step 3: Add the rare earth oxides to the glass-ceramic system and mix evenly to obtain a mixture;

[0032] Step 4: After high-temperature melting and rapid water cooling of the mixture, glass fibers are obtained;

[0033] Step 5: After uniformly mixing glass fiber and a special solvent in a predetermined ratio and degassing, screen printing is carried out to obtain a sealing material with a specific shape.

[0034] Specifically, through experimental verification, the present invention knows that in the development of glass-ceramic sealing materials for solid oxide electrolytic cells (SOECs), the introduction of rare earth oxides significantly optimizes the comprehensive performance of the materials, especially in terms of high and low temperature matching, chemical stability, and mechanical strength. The present invention discovers that by adjusting the types and addition ratios of rare earth oxides (such as Y2O3, CeO2, La2O3, etc.), the thermal expansion coefficient of the glass-ceramic (8 - 11 ppm / °C) can be effectively regulated to highly match the thermal expansion behavior of the SOEC metal interconnect (such as Crofer22APU alloy), thereby reducing interfacial stress and enhancing sealing reliability. At the same time, the addition of rare earth elements can refine the grains and purify the glass phase, reduce impurities and pores at the grain boundaries, and enhance the density and creep resistance of the material. For example, the introduction of CeO2 can significantly improve the thermal shock resistance of the coating and extend the thermal cycle failure life.

[0035] In addition, rare earth oxides (such as the Y2O3 and CeO2 composite system) promote low-temperature densification sintering by forming eutectic liquid phases, reduce process energy consumption, and at the same time enhance the high-temperature corrosion resistance and chemical compatibility of the coating, reducing mechanical sand sticking defects caused by melt penetration. In terms of long-term stability, the rare earth-doped glass-ceramics can still maintain good airtightness at high temperatures (>1000 hours) and in an alternating oxidation / reduction environment, and its mechanism may be related to the stabilizing effect of rare earth elements on the interfacial oxide film. For example, CeO2 can enhance the adhesion of the oxide film and inhibit the propagation of interfacial cracks.

[0036] In summary, rare earth oxides can achieve high sealing performance of glass-ceramic sealing materials. Therefore, the present invention provides a preparation method for a rare earth-containing solid oxide electrolytic cell sealing material. Please refer to Figure 1 , first, through Step 1, set the predetermined mass ratio range of the rare earth oxide and the glass-ceramic system. Since different mass ratios of the two will result in incomplete identical performances of the prepared sealing materials, the present invention can specifically set the mass ratio according to the actual usage scenario. For example, the mass ratio range of the rare earth oxide to the glass-ceramic system can be set to 1% - 20% according to needs.

[0037] After setting the mass ratio range, in step 2, according to the range set in step 1, rare earth oxides and a glass-ceramic system with appropriate masses are selected to meet the above mass ratio range. After taking out the rare earth oxides and the glass-ceramic system, in step 3, the rare earth oxides are added to the glass-ceramic system and the two are mixed evenly to obtain a mixture. In this embodiment, the rare earth oxides can be, for example, one or several of La2O3, Sm2O3, CeO2, Nd2O3, Gd2O3, and Y2O3, and the glass-ceramic system is CaO-MgO-Al2O3-SiO2-B2O3-ZrO2.

[0038] After obtaining the mixture, in step 4, the mixture is subjected to high-temperature melting and rapid water cooling to obtain glass fibers. Since it is necessary to mix the glass fibers with a special solvent during screen printing, after obtaining the glass fibers, they are ground into powder to facilitate mixed printing.

[0039] After obtaining the glass fiber powder, in step 5, the glass fibers and the special solvent are uniformly mixed in a predetermined ratio and degassed, and then screen printing can be carried out to obtain a sealing material with a specific shape. Here, the predetermined ratio of the glass fibers and the special solvent can be set according to the specific use scenario, for example, set to 1:1, 1.5:1, or 2:1. In addition, in this embodiment, the special solvent includes a first solvent, a binder, a dispersant, and a plasticizer, and the ratio of the first solvent, the binder, the dispersant, and the plasticizer is 62:1:6:5.

[0040] After obtaining the above sealing material, the solid oxide electrolyzer stack can be assembled for sealing performance testing. In this embodiment, the four-wire method can be used to test the open-circuit voltage at both ends of a single or multiple cells. The theoretical open-circuit voltages of a single hydrogen-oxygen fuel cell at 850 °C with hydrogen passing through water and 50% H2O-H2 are approximately 1.06 V and 0.96 V respectively, and the experimental results are as high as 94% and 96.9% of the theoretical open-circuit voltage respectively. It can be seen that by introducing rare earth oxides into the glass-ceramic system, the present invention can effectively improve the sealing performance of the solid oxide electrolyzer.

[0041] The preparation method of the rare earth-containing solid oxide electrolyzer sealing material provided by the present invention regulates the thermal expansion coefficient (8-11 ppm / °C) and chemical stability by introducing rare earth oxides (such as CeO2, Y2O3), enabling it to meet the harsh operating environment of SOEC at high temperatures (700-900 °C) and high water vapor partial pressures (>50% H2O), and solving the problem of airtightness failure caused by ion migration and hydration corrosion of traditional sealing materials containing alkali (Na+ / K+) or alkaline earth metals (Ba 2 +) at the same time, and preparing the glass-ceramic powder into a sealing material for application in solid oxide electrolyzers.

[0042] Based on the same inventive concept, the present invention also provides a rare-earth-containing solid oxide electrolyzer sealing material, which comprises components: glass fiber and a special solvent; wherein, the glass fiber comprises rare-earth oxides and a glass-ceramic system.

[0043] Specifically, through experimental verification, the present invention knows that in the development of a glass-ceramic sealing material for a solid oxide electrolyzer (SOEC), the introduction of rare-earth oxides significantly optimizes the comprehensive performance of the material, especially outstanding in terms of high and low temperature matching, chemical stability and mechanical strength. The present invention discovers that by adjusting the types and addition ratios of rare-earth oxides (such as Y2O3, CeO2, La2O3, etc.), the thermal expansion coefficient of the glass-ceramic (8-11 ppm / °C) can be effectively regulated to highly match the thermal expansion behavior of the SOEC metal interconnect (such as Crofer22APU alloy), thereby reducing the interfacial stress and improving the sealing reliability. At the same time, the addition of rare-earth elements can refine the grains and purify the glass phase, reduce impurities and pores at the grain boundaries, and enhance the density and creep resistance of the material. For example, the introduction of CeO2 can significantly improve the thermal shock resistance of the coating and extend the thermal cycle failure life.

[0044] In addition, rare-earth oxides (such as the Y2O3 and CeO2 composite system) promote low-temperature densification sintering by forming a eutectic liquid phase, reduce the process energy consumption, and at the same time improve the high-temperature corrosion resistance and chemical compatibility of the coating, reducing mechanical sand sticking defects caused by melt penetration. In terms of long-term stability, the rare-earth-doped glass-ceramic can still maintain good airtightness in a high-temperature (>1000 hours) and oxidation / reduction alternating environment, and its mechanism may be related to the stabilizing effect of rare-earth elements on the interfacial oxide film. For example, CeO2 can enhance the adhesion of the oxide film and inhibit the propagation of interfacial cracks.

[0045] In summary, rare-earth oxides can achieve high sealing performance of the glass-ceramic sealing material. Therefore, the present invention provides a rare-earth-containing solid oxide electrolyzer sealing material, which comprises glass fiber and a special solvent; wherein, the glass fiber comprises rare-earth oxides and a glass-ceramic system.

[0046] Due to different mass ratios of rare-earth oxides and the glass-ceramic system, the performance of the prepared sealing material will not be completely the same. Therefore, the present invention can specifically set the mass ratio of the two according to the actual use scenario. For example, the mass ratio range of rare-earth oxides to the glass-ceramic system can be set to 1%-20% according to needs.

[0047] After setting the mass ratio range, rare earth oxides and a glass-ceramic system with appropriate masses can be selected to meet the above mass ratio range. The rare earth oxides are added to the glass-ceramic system and mixed evenly to obtain a mixture. In this embodiment, the rare earth oxides can be, for example, one or several of La2O3, Sm2O3, CeO2, Nd2O3, Gd2O3, and Y2O3, and the glass-ceramic system is CaO-MgO-Al2O3-SiO2-B2O3-ZrO2.

[0048] After obtaining the mixture, it is subjected to high-temperature melting and rapid water cooling to obtain glass fibers. Since the glass fibers need to be mixed with a special solvent during screen printing, after obtaining the glass fibers, they are ground into powder to facilitate mixed printing.

[0049] After the glass fibers and the special solvent are uniformly mixed in a predetermined ratio and degassed, screen printing can be carried out to obtain a sealing material with a specific shape. Here, the predetermined ratio of the glass fibers and the special solvent can be set according to the specific usage scenario, for example, set to 1:1, 1.5:1, or 2:1. In addition, in this embodiment, the special solvent includes a first solvent, a binder, a dispersant, and a plasticizer, and the ratio of the first solvent, the binder, the dispersant, and the plasticizer is 62:1:6:5.

[0050] After obtaining the above sealing material, the solid oxide electrolyzer stack can be assembled for sealing performance testing. In this embodiment, the four-wire method can be used to test the open-circuit voltage at both ends of a single or multiple cells. The theoretical open-circuit voltages of a single hydrogen-oxygen fuel cell at 850 °C with water-saturated hydrogen and 50% H2O-H2 are approximately 1.06 V and 0.96 V respectively, and the experimental results are as high as 94% and 96.9% of the theoretical open-circuit voltage respectively. It can be seen that by introducing rare earth oxides into the glass-ceramic system, the present invention can effectively improve the sealing performance of the solid oxide electrolyzer.

[0051] The rare-earth-containing solid oxide electrolyzer sealing material provided by the present invention regulates the thermal expansion coefficient (8 - 11 ppm / °C) and chemical stability by introducing rare earth oxides (such as CeO2, Y2O3), enabling it to meet the harsh operating environments of high temperature (700 - 900 °C) and high water vapor partial pressure (>50% H2O) of SOEC, and solving the problem of airtightness failure caused by ion migration and hydration corrosion of traditional sealing materials containing alkali (Na+ / K+) or alkaline earth metals (Ba 2 +) at the same time, and preparing the glass-ceramic powder into a sealing material for application in solid oxide electrolyzers.

[0052] Those of ordinary skill in the art can understand that the drawings are only schematic diagrams of one embodiment, and the modules or processes in the drawings are not necessarily essential for implementing the present invention.

[0053] Those of ordinary skill in the art can understand that the modules in the device in the embodiments can be distributed in the device in the embodiments as described in the embodiments, or can be correspondingly changed and located in one or more devices different from this embodiment. The modules in the above embodiments can be combined into one module, or can be further split into multiple sub-modules.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A preparation method of a rare earth-containing solid oxide electrolytic cell sealing material, characterized in that Including: Setting a predetermined mass ratio range of rare earth oxides and glass-ceramic systems; Taking rare earth oxides and glass-ceramic systems with masses meeting the requirements according to the predetermined mass ratio range of the rare earth oxides and glass-ceramic systems; Adding the rare earth oxides into the glass-ceramic system and mixing evenly to obtain a mixture; After subjecting the mixture to high-temperature melting and rapid water cooling, glass fibers are obtained; After uniformly mixing the glass fibers and a special solvent in a predetermined ratio and degassing, screen printing is carried out to obtain a sealing material with a specific shape.

2. The preparation method of the rare earth-containing solid oxide electrolytic cell sealing material according to claim 1, characterized in that, The mass ratio range of the rare earth oxides to the glass-ceramic system is 1% - 20%.

3. The rare earth-containing solid oxide electrolytic cell sealing material according to claim 2, wherein, The predetermined ratio of the glass fibers to the special solvent is 1:

1.

4. The rare earth-containing solid oxide electrolytic cell sealing material according to claim 2, characterized in that, The predetermined ratio of the glass fibers to the special solvent is 1.5:

1.

5. The rare earth-containing solid oxide electrolytic cell sealing material according to claim 2, characterized in that, The predetermined ratio of the glass fibers to the special solvent is 2:

1.

6. The preparation method of the rare earth-containing solid oxide electrolytic cell sealing material according to claim 1, characterized in that, The special solvent includes a first solvent, a binder, a dispersant, and a plasticizer.

7. The preparation method of the rare earth-containing solid oxide electrolytic cell sealing material according to claim 6, characterized in that, The ratio of the first solvent, the binder, the dispersant, and the plasticizer is 62:1:6:

5.

8. The preparation method of the rare earth-containing solid oxide electrolytic cell sealing material according to claim 1, characterized in that, The rare earth oxides include one or more of La2O3, Sm2O3, CeO2, Nd2O3, Gd2O3, and Y2O3.

9. A rare earth-containing solid oxide electrolytic cell sealing material, characterized in that, Comprising components: glass fibers and a special solvent; wherein, The glass fibers include rare earth oxides and a glass-ceramic system.

10. The preparation method of the rare earth-containing solid oxide electrolytic cell sealing material according to claim 9, characterized in that, The rare earth oxides include one or more of La2O3, Sm2O3, CeO2, Nd2O3, Gd2O3, and Y2O3.

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