Symmetrical solid oxide electrolytic cell electrode material as well as preparation method and application thereof

Abstract

The invention discloses a symmetric solid oxide electrolytic cell electrode material and a preparation method and application thereof in the technical field of solid oxide electrolytic cell materials, the molecular formula of the symmetric solid oxide electrolytic cell electrode material is Pr0. 5Ba0. 5Mn0. 95-xMexPt0. 05O3-delta (PBMMePt), x is greater than or equal to 0 and less than or equal to 0.1, and Me is selected from one of Fe and Co. The symmetric solid oxide electrolytic cell electrode material provided by the invention does not destroy the perovskite structure of original powder after hydrogen calcination, a dissolution phenomenon occurs on the surface, the Pt element forms nanoparticles on the surface of the material, a noble metal-metal oxide heterostructure is constructed, the adsorption area is increased, numerous reaction active sites are provided, and the performance of the electrode material is improved. The chemical adsorption of the electrode on CO2 and the transmission of oxygen ions are promoted, and the catalytic activity of the material is improved.

Description

Technical Field

[0001] The invention relates to the technical field of solid oxide electrolytic cell materials, and in particular to a symmetrical solid oxide electrolytic cell electrode material and a preparation method and application thereof. Background Art

[0002] The energy structure dominated by traditional fossil energy in the 21st century will cause serious environmental pollution problems and threaten people's physical and mental health. In order to avoid the negative impact of climate change on human beings, it is of great significance to achieve low-carbon development in the whole society. Although wind and solar energy can easily provide enough electricity to meet global energy needs, these energy sources are subject to volatility, intermittency and periodicity, which requires us to rethink and design the energy system. People urgently need to develop and apply more efficient and clean energy production and utilization methods to solve the problems of reserves and pollution brought by traditional fossil energy and achieve the goal of carbon neutrality as soon as possible. In recent years, solid oxide electrolysis cells have received widespread attention due to their extensive applications in industry, commerce and science, especially in the context of vigorously developing renewable energy, showing broad application prospects in energy storage. Traditional electrode materials such as lanthanum strontium cobalt iron LSCF, strontium iron molybdenum SFM and praseodymium barium strontium cobalt iron PBSCF have many problems, including poor adsorption of CO2, low electrocatalytic activity and unstable operation. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a symmetrical solid oxide electrolytic cell electrode material and a preparation method and application thereof. The symmetrical solid oxide electrolytic cell electrode material does not destroy the perovskite structure of the original powder after hydrogen calcination, and dissolution occurs on the surface. The Pt element forms nanoparticles on the surface of the material, constructs a "precious gold-metal oxide" heterostructure, increases the adsorption area, provides numerous reaction active sites, promotes the chemical adsorption of CO2 and the transmission of oxygen ions by the electrode, and improves the catalytic activity of the material.

[0004] To achieve the above object, the present invention is implemented by adopting the following technical solutions:

[0005] In the first aspect, the present invention provides a symmetrical solid oxide electrolytic cell electrode material having a molecular formula of Pr 0.5 Ba 0.5 Mn 0.95-x Me x Pt 0.05 O 3-δ , denoted as PBMMePt, where 0≤x≤0.1, and Me is selected from one of Fe and Co.

[0006] Furthermore, the molecular formula is Pr 0.5 Ba 0.5 Mn0.95 Pt 0.05 O 3-δ or Pr 0.5 Ba 0.5 Mn 0.85 Me 0.1 Pt 0.05 O 3-δ .

[0007] In a second aspect, the present invention provides a method for preparing the symmetrical solid oxide electrolytic cell electrode material, comprising the following steps:

[0008] Obtaining raw materials according to the stoichiometric ratio of the molecular formula of the symmetrical solid oxide electrolytic cell material and fully dissolving them in water, wherein the raw materials include praseodymium nitrate or its hydrate, barium nitrate or its hydrate, manganese nitrate or its hydrate, platinum tetrachloride or its hydrate, iron nitrate or its hydrate, and cobalt nitrate or its hydrate;

[0009] adding citric acid and ethylenediaminetetraacetic acid to adjust the pH of the solution, and stirring the solution until it becomes a gel to obtain a gel;

[0010] The gel is fully dried to obtain a black precursor;

[0011] The black precursor is ground into powder, and calcined to obtain a symmetrical solid oxide electrolytic cell material.

[0012] Furthermore, the addition ratio of citric acid and ethylenediaminetetraacetic acid is (1-1.5):1.

[0013] Further, said adjusting the pH of the solution comprises adjusting the pH of the solution to 6-8;

[0014] And / or, the temperature condition for stirring the solution until it becomes gel-like includes a temperature of 70-80°C.

[0015] Furthermore, the step of fully drying the gel comprises drying the gel in a vacuum oven at 200-400° C. for 5-8 hours.

[0016] And / or, the calcining comprises continuing calcining at 900-1050° C. for 8-10 hours.

[0017] In a third aspect, the present invention provides a use of the symmetrical solid oxide electrolytic cell electrode material in an electrode of a symmetrical solid oxide electrolytic cell.

[0018] Furthermore, the symmetrical solid oxide electrolysis cell is used for electrolysis of CO2, and the application process comprises:

[0019] A symmetrical solid oxide electrolytic cell electrode material is obtained, and the electrode material is ground and mixed evenly with pinene alcohol to prepare an electrode slurry;

[0020] Obtaining LDC powder, grinding it and mixing it evenly with pinene alcohol to prepare lanthanum-doped cerium oxide LDC slurry;

[0021] Obtain a lanthanum strontium gallium magnesium LSGM electrolyte sheet, coat LDC slurry on both sides of the LSGM electrolyte sheet, dry and calcine, then coat electrode slurry on both sides respectively, dry and calcine, to prepare a PBMMePt|LDC|LSGM|LDC|PBMMePt symmetric solid oxide electrolytic cell;

[0022] The symmetrical solid oxide electrolytic cell was placed in the furnace of a tube furnace and fixed, the air was evacuated after sealing, and then a 20V / V% H2 / Ar mixed gas was introduced for calcination to obtain an electrode material of PrBaMn 1.9-y Me y Pt 0.1 O 5+δ The symmetrical solid oxide electrolytic cell, the PrBaMn 1.9-y Me y Pt 0.1 O 5+δ The material is recorded as L-PBMMePt, wherein 0≤y≤0.2, and Me is selected from one of Fe and Co.

[0023] Furthermore, the mass ratio of the symmetrical solid oxide electrolytic cell electrode material to pineol is (1-1.5):1;

[0024] And / or, the mass ratio of the LDC powder to pineol is (1-1.5):1.

[0025] And / or, coating LDC slurry on both sides of the LSGM electrolyte sheet, drying and calcining, and then coating electrode slurry on both sides respectively, drying and calcining, wherein the two calcinations include calcining at 1000-1200° C. for 3-5 hours.

[0026] Furthermore, the symmetrical solid oxide electrolytic cell is placed in a tube furnace and fixed, the air is evacuated after sealing, and then a 20V / V% H2 / Ar mixed gas is introduced for calcination, wherein the calcination includes calcination at 500-600°C for 1-2h.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The symmetrical solid oxide electrolytic cell electrode material provided by the present invention uses Pt-doped Pr 0.5 Ba 0.5 MnO 3-δ , Pr 0.5 Ba 0.5 Mn 0.9 Fe 0.1 O 3-δand Pr 0.5 Ba 0.5 Mn 0.9 Co 0.1 O 3-δ As a symmetrical electrode material for solid oxide electrolytic cells, the perovskite structure of the original powder is not destroyed after hydrogen calcination, and the surface undergoes dissolution. The Pt element forms nanoparticles on the surface of the material, constructing a "precious gold-metal oxide" heterostructure, increasing the adsorption area, providing numerous reactive sites, increasing the three-phase interface, promoting the chemical adsorption of CO2 and the transmission of oxygen ions by the electrode, and improving the catalytic activity of the material.

[0029] Due to the construction of the "noble gold-metal oxide" heterostructure, the material produces a large number of oxygen vacancies, which can improve the catalyst's adsorption capacity for reactants, reduce the activation energy barrier of the reaction, promote the reaction, anchor Pt nanoparticles during the electrolysis process, avoid agglomeration, and enhance the atomic utilization of Pt active sites and the stability of the material.

[0030] The method for preparing the electrode material of the symmetrical solid oxide electrolytic cell provided by the present invention uses low-cost materials and is simple and easy to prepare. The electrolytic cell prepared by the method can be used for the electrolysis of CO2 and can be used for the efficient electrolysis of carbon dioxide in SOEC. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is the XRD spectrum of PBMPt, PBMFePt and PBMCoPt powders provided in the embodiments of the present invention;

[0032] Figure 2 is the XRD spectrum of L-PBMPt, L-PBMFePt and L-PBMCoPt powders provided in the embodiments of the present invention;

[0033] Figure 3 is a SEM image of L-PBMPt powder provided in an embodiment of the present invention;

[0034] Figure 4 is a SEM image of L-PBMFePt powder provided in an embodiment of the present invention;

[0035] Figure 5 is a SEM image of L-PBMCoPt powder provided in an embodiment of the present invention;

[0036] Figure 6 2 is the CO2-TPD curve of L-PBMPt, L-PBMFePt and L-PBMCoPt powders provided in the embodiments of the present invention;

[0037] Figure 7It is an IV polarization curve diagram of the PBMPt powder provided by an embodiment of the present invention at different temperatures in a 20% CO2 / N2 atmosphere;

[0038] Figure 8 It is an IV polarization curve diagram of the PBMFePt powder provided by an embodiment of the present invention at different temperatures in a 20% CO2 / N2 atmosphere;

[0039] Fig. 9 This is an IV polarization curve diagram of the PBMCoPt powder provided in an embodiment of the present invention at different temperatures in a 20% CO2 / N2 atmosphere. DETAILED DESCRIPTION

[0040] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0041] Example 1

[0042] This embodiment provides a symmetrical solid oxide electrolytic cell electrode material and a preparation method thereof. The molecular formula of the symmetrical solid oxide electrolytic cell electrode material is Pr 0.5 Ba 0.5 Mn 0.95 Pt 0.05 O 3-δ (PBMPt), the preparation method thereof comprises:

[0043] At room temperature, in a beaker, 1.0875g of praseodymium nitrate, 0.6533g of barium nitrate, 0.8500g of manganese nitrate dihydrate, and 0.0842g of platinum tetrachloride were added to a beaker containing 200mL of pure water and stirred for 30 minutes; then 5mmol of ethylenediaminetetraacetic acid 2.3224g and 7.5mmol of citric acid 2.8818g were added, and after stirring for 30 minutes, ammonia water was used to adjust the pH to about 7. The mixture was placed on a magnetic stirrer, the heating plate was set to 80°C and stirred continuously until gel-like. The gel was dried in a vacuum oven at 250°C for 5 hours to obtain a black precursor. Finally, the black precursors were ground into powder and calcined at 1050°C for 10 hours to obtain a PBMPt symmetric solid oxide electrolytic cell electrode material.

[0044] Example 2

[0045] This embodiment provides a symmetrical solid oxide electrolytic cell electrode material and a preparation method thereof. The molecular formula of the symmetrical solid oxide electrolytic cell electrode material is Pr 0.5 Ba 0.5 Mn 0.85 Fe 0.1 Pt 0.05 O 3-δ(PBMFePt), the preparation method thereof comprises:

[0046] At room temperature, 1.0875g praseodymium nitrate, 0.6533g barium nitrate, 0.7605g manganese nitrate dihydrate, 0.0842g platinum tetrachloride, and 0.2019g iron nitrate nine hydrate were added to a beaker containing 200mL of pure water and stirred for 30 minutes; then 5mmol ethylenediaminetetraacetic acid 2.3224g, 7.5mmol citric acid 2.8818g were added, and after stirring for 30 minutes, ammonia water was used to adjust the pH to about 7. The mixture was placed on a magnetic stirrer, the heating plate was set to 80°C and stirred continuously until gel-like. The gel was dried in a vacuum oven at 250°C for 5 hours to obtain a black precursor. Finally, the black precursors were ground into powder and calcined at 1050°C for 10 hours to obtain a PBMFePt symmetric solid oxide electrolytic cell electrode material.

[0047] Example 3

[0048] This embodiment provides a symmetrical solid oxide electrolytic cell electrode material and a preparation method thereof. The molecular formula of the symmetrical solid oxide electrolytic cell electrode material is Pr 0.5 Ba 0.5 Mn 0.85 Co 0.1 Pt 0.05 O 3-δ (PBMCoPt), the preparation method thereof comprising:

[0049] At room temperature, 1.0875g of praseodymium nitrate, 0.6533g of barium nitrate, 0.7605g of manganese nitrate dihydrate, 0.0842g of platinum tetrachloride, and 0.1455g of cobalt nitrate hexahydrate were added to a beaker containing 200mL of pure water and stirred for 30 minutes; then 5mmol of ethylenediaminetetraacetic acid 2.3224g and 7.5mmol of citric acid 2.8818g were added, and after stirring for 30 minutes, ammonia water was used to adjust the pH to about 7. The mixture was placed on a magnetic stirrer, the heating plate was set to 80°C and stirred continuously until gel-like. The gel was dried in a vacuum oven at 250°C for 5 hours to obtain a black precursor. Finally, the black precursors were ground into powder and calcined at 1050°C for 10 hours to obtain a PBMCoPt symmetric solid oxide electrolytic cell electrode material.

[0050] Example 4

[0051] This embodiment provides an application of a symmetrical solid oxide electrolytic cell electrode material, wherein the symmetrical solid oxide electrolytic cell electrode material is the PBMPt provided in Embodiment 1, the PBMFePt provided in Embodiment 2, or the PBMCoPt provided in Embodiment 3, and the application process includes:

[0052] Obtaining a symmetrical solid oxide electrolytic cell electrode material, grinding it, and fully mixing it with pineol to prepare an electrode slurry, wherein the mass ratio of the symmetrical solid oxide electrolytic cell electrode material to pineol is 1.5:1;

[0053] Obtain LDC powder, grind it and mix it with pineol to prepare LDC slurry, wherein the mass ratio of LDC powder to pineol is 1.5:1;

[0054] Obtain an LSGM electrolyte sheet, apply LDC slurry on both sides of the LSGM electrolyte sheet by screen printing, dry and calcine at 1000°C for 3h, then apply electrode slurry on both sides by screen printing, dry and calcine at 1000°C for 3h, and prepare a PBMMePt|LDC|LSGM|LDC|PBMMePt symmetric solid oxide electrolytic cell;

[0055] The symmetrical solid oxide electrolytic cell was placed in the furnace of a tube furnace and fixed, and the air was evacuated after sealing. Then, a 20V / V% H2 / Ar mixed gas was introduced and calcined at 600°C for 2h to obtain an electrode material of PrBaMn 1.9 Pt 0.1 O 5+δ (L-PBMPt), PrBaMn 1.7 Fe 0.2 Pt 0.1 O 5+δ (L-PBMFePt) or PrBaMn 1.7 Co 0.2 Pt 0.1 O 5+δ Symmetric solid oxide electrolysis cell of (L-PBMCoPt).

[0056] The PBMPt provided in Example 1, the PBMFePt provided in Example 2, and the PBMCoPt provided in Example 3 were ground in an agate mortar for half an hour, poured into a ceramic ark and spread evenly, and the ceramic ark was placed in the middle of a tube furnace, sealed and evacuated of air, and then introduced into a 20V / V% H2 / Ar mixed gas, and calcined at 600°C for 2h to obtain PrBaMn 1.9 Pt 0.1 O 5+δ (L-PBMPt), PrBaMn 1.7 Fe 0.2 Pt 0.1 O 5+δ (L-PBMFePt) and PrBaMn 1.7 Co 0.2 Pt 0.1 O 5+δ(L-PBMCoPt) powders were characterized separately to compare with the symmetrical solid oxide electrolytic cell electrode materials provided in Example 4.

[0057] Figure 1 is the XRD spectrum of PBMPt, PBMFePt and PBMCoPt powders provided in the embodiments of the present invention, Figure 1 It can be seen that the PBMPt, PBMFePt and PBMCoPt perovskite oxides synthesized in air at 1050°C show a simple perovskite structure with a mixture of cubic and hexagonal phases, and no observable second phase. This indicates that the Pt element is successfully doped into the lattice of the material. Since the ionic radius of Fe and Co is smaller than the ionic radius of the substituted Mn, the XRD diffraction peaks of PBMFePt and PBMCoPt are slightly shifted to high X-ray diffraction angles relative to PBMPt.

[0058] Figure 2 is the XRD spectrum of L-PBMPt, L-PBMFePt and L-PBMCoPt powders provided in the embodiments of the present invention, Figure 2 It can be seen that L-PBMPt, L-PBMFePt, and L-PBMCoPt are all in cubic phase, indicating that the sample undergoes a structural transformation after calcination, from a typical single perovskite structure to a layered perovskite structure with multi-level repetition. It is worth noting that new X-ray diffraction peaks appeared at two X-ray diffraction angles of 39.9° and 46.4°. Through Jade software analysis, these two diffraction peaks coincide with the diffraction peaks of metal Pt. Therefore, it is speculated that after hydrogen calcination, Pt in the material lattice undergoes dissolution, forming Pt nanoparticles on the surface of the layered perovskite oxide, forming a "precious gold-metal oxide" heterostructure.

[0059] In order to observe the microstructure of the materials, SEM tests were carried out on L-PBMPt, L-PBMFePt and L-PBMCoPt. Figure 3 , 4 As shown in Figure 5. As can be seen from the figure, nanoparticles appeared on the surface of the three samples, especially the number of nanoparticles on the surface of L-PBMCoPt was significantly greater than that of the other two materials. More nanoparticles and smaller particle sizes construct a large number of "precious gold-metal oxide" heterostructures, increase the adsorption area, provide numerous reaction sites, and facilitate the transport of adsorbed oxygen ions of CO2, thereby improving the catalytic activity of the electrode material.

[0060] In the process of electrocatalytic calcination of CO2, the first thing that happens is the adsorption of CO2 by the electrode material. Therefore, the adsorption capacity of the electrode material for CO2 is an important factor affecting the electrocatalytic activity of the electrode material. Studies have shown that the desorption peak in the CO2-TPD curve in the temperature range of 100~400°C is caused by the desorption of CO2 physically adsorbed on the surface of the material, while the desorption peak in the temperature range of 400~900°C is caused by the desorption of CO2 chemically adsorbed on the surface of the material. Figure 6 The CO2-TPD curves of L-PBMPt, L-PBMFePt and L-PBMCoPt powders provided in the embodiments of the present invention are shown in FIG. Figure 6 In the figure, L-PBMCoPt has an obvious desorption peak in the low temperature range relative to L-PBMPt and L-PBMFePt, which indicates that PBMCoPt has better physical adsorption capacity and a larger specific surface area. In the high temperature region, the desorption curve intensity of L-PBMCoPt is significantly greater than that of L-PBMPt and L-PBMFePt and has been on an upward trend without a desorption peak, which indicates that the peak position of the desorption peak moves toward a higher temperature. This is because L-PBMCoPt has a large amount of "precious gold-metal oxide" heterogeneous structure, which improves the chemical adsorption capacity of the catalyst for CO2.

[0061] Figure 7 , 8 and Fig. 9 It is the IV polarization curve diagram of PBMPt, PBMFePt and PBMCoPt powders provided by the embodiments of the present invention at different temperatures in a 20% CO2 / N2 atmosphere. It can be seen from the figure that the maximum current density of the PBMCoPt symmetric solid oxide electrolytic cell is about 27% and 15% higher than the maximum current density of PBMPt and PBMFePt, respectively, showing the best CO2 electrolysis performance. This is attributed to the fact that after hydrogen calcination of the PBMCoPt symmetric electrode, the Pt element dissolves to form the most Pt nanoparticles with the smallest particle size, providing numerous reaction active sites, increasing the three-phase interface, promoting the chemical adsorption of CO2 and the transmission of oxygen ions, and having a positive impact on the overall performance of the material.

[0062] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the enlightenment of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the purpose of the present invention and the claims, which all fall within the protection of the present invention.

Claims

1. A symmetrical solid oxide electrolytic cell electrode material, characterized in that: The molecular formula is Pr 0.5 Ba 0.5 Mn 0.95- x Me x Pt 0.05 O 3-δ , denoted as PBMMePt, where 0≤x≤0.1, and Me is selected from one of Fe and Co.

2. The symmetrical solid oxide electrolytic cell electrode material according to claim 1, characterized in that: The molecular formula is Pr 0.5 Ba 0.5 Mn 0.95 Pt 0.05 O 3-δ or Pr 0.5 Ba 0.5 Mn 0.85 Me 0.1 Pt 0.05 O 3-δ .

3. A method for preparing a symmetrical solid oxide electrolytic cell electrode material as claimed in claim 1 or 2, characterized in that: The following steps are involved: Obtaining raw materials according to the stoichiometric ratio of the molecular formula of the symmetrical solid oxide electrolytic cell material and dissolving them in water, wherein the raw materials include praseodymium nitrate or its hydrate, barium nitrate or its hydrate, manganese nitrate or its hydrate, platinum tetrachloride or its hydrate, iron nitrate or its hydrate and cobalt nitrate or its hydrate; adding citric acid and ethylenediaminetetraacetic acid to adjust the pH of the solution, and stirring the solution until it becomes a gel to obtain a gel; Drying the gel to obtain a black precursor; The black precursor is ground into powder, and calcined to obtain a symmetrical solid oxide electrolytic cell material.

4. The method for preparing a symmetrical solid oxide electrolytic cell electrode material according to claim 2, characterized in that: The addition ratio of citric acid and ethylenediaminetetraacetic acid is (1-1.5):

1.

5. The method for preparing the electrode material for a symmetrical solid oxide electrolytic cell according to claim 2, characterized in that: The step of adjusting the pH of the solution comprises adjusting the pH of the solution to 6-8; And / or, the temperature condition for stirring the solution until it becomes gel-like includes a temperature of 70-80°C.

6. The method for preparing the electrode material for a symmetrical solid oxide electrolytic cell according to claim 2, characterized in that: The drying of the gel comprises drying in a vacuum oven at 200-400° C. for 5-8 hours; And / or, the calcining comprises continuing calcining at 900-1050° C. for 8-10 hours.

7. Use of the symmetrical solid oxide electrolytic cell electrode material according to claim 1 or 2 in an electrode of a symmetrical solid oxide electrolytic cell.

8. The use of the symmetrical solid oxide electrolytic cell electrode material according to claim 7, characterized in that: The symmetrical solid oxide electrolysis cell is used for electrolysis of CO2, and the application process comprises: A symmetrical solid oxide electrolytic cell electrode material is obtained, and the electrode material is uniformly mixed with pinene alcohol to prepare an electrode slurry; Obtaining LDC powder, and mixing it evenly with pinene alcohol to prepare lanthanum-doped cerium oxide LDC slurry; Obtain a lanthanum strontium gallium magnesium LSGM electrolyte sheet, coat LDC slurry on both sides of the LSGM electrolyte sheet, dry and calcine, then coat electrode slurry on both sides respectively, dry and calcine, to prepare a PBMMePt|LDC|LSGM|LDC|PBMMePt symmetric solid oxide electrolytic cell; The symmetrical solid oxide electrolytic cell was placed in the furnace of a tube furnace and fixed, the air was evacuated after sealing, and then a 20V / V% H2 / Ar mixed gas was introduced for calcination to obtain an electrode material of PrBaMn 1.9-y Me y Pt 0.1 O 5+δ The symmetrical solid oxide electrolytic cell, the PrBaMn 1.9-y Me y Pt 0.1 O 5+δ The material is recorded as L-PBMMePt, wherein 0≤y≤0.2, and Me is selected from one of Fe and Co.

9. The method for preparing a symmetrical solid oxide electrolytic cell according to claim 8, characterized in that: The mass ratio of the electrode material of the symmetrical solid oxide electrolytic cell to pinene alcohol is (1-1.5): 1; And / or, the mass ratio of the LDC powder to terpineol is (1-1.5):1; And / or, coating LDC slurry on both sides of the LSGM electrolyte sheet, drying and calcining, and then coating electrode slurry on both sides respectively, drying and calcining, wherein the two calcinations include calcining at 1000-1200° C. for 3-5 hours.

10. The method for preparing a symmetrical solid oxide electrolytic cell according to claim 8, characterized in that: The symmetrical solid oxide electrolytic cell is placed in the furnace of a tubular furnace and fixed, and the air is evacuated after sealing, and then a 20V / V% H2 / Ar mixed gas is introduced for calcination, wherein the calcination includes calcination at 500-600°C for 1-2h.

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