Porous electrode material, electrode and method for producing the same and solid oxide electrolysis cell

Abstract

The application belongs to the technical field of new materials, and discloses a porous electrode material, an electrode and a preparation method thereof and a solid oxide electrolysis cell. 1.5 Mo 0.5‑x W x O6- δ wherein x represents a molar fraction, and the value range of x is 0 1.5 Mo 0.5 O6 perovskite material, a W-doped Mo is used to replace part of Mo, and a porous electrode material is designed by using the higher valence and electronegativity of W relative to Fe and Mo, and the smaller ionic radius of W relative to Mo. The electrode material not only has high CO2 adsorption, but also has high temperature stability and high catalytic activity. When the electrode material is applied to the oxide solid electrolysis cell, the current density of SOEC electrolysis CO2 is effectively improved, and the polarization resistance of the material is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of new materials, and particularly relates to a porous electrode material, an electrode, a preparation method thereof, and a solid oxide electrolyzer. Background Art

[0002] As a core device for CO2 conversion and hydrogen production, high-temperature solid oxide electrolyzers (SOECs) have become a focus in the energy field. The performance of SOECs mainly depends on the cathode material, which requires excellent ionic-electronic mixed conductivity, high-efficiency CO2 adsorption and activation ability, and structural stability at 600 - 900 °C.

[0003] Sr2FeMo 0.5 O6 (SFM) perovskite has become a potential material for SOEC cathodes due to its balanced ionic and electronic conductivities. However, facing the industrial demand for "high current and long life", the shortcomings of pure-phase SFM are prominent. For example, during the sintering process, it is prone to particle agglomeration, resulting in relatively large powder particle sizes and low specific surface areas, making it difficult to provide sufficient active sites, thereby limiting the adsorption and activation efficiency of CO2 molecules on the cathode surface, ultimately resulting in insufficient CO2 adsorption capacity and restricting the improvement of the electrochemical performance of the electrode. These deficiencies limit the commercial application of SFM in SOECs.

[0004] Therefore, it is crucial to develop a SOEC cathode material with high CO2 adsorption capacity and high performance. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. For this purpose, the present invention provides a porous electrode material, an electrode, a preparation method thereof, and a solid oxide electrolyzer. The porous electrode material has a high CO2 adsorption capacity, and also has high-temperature stability and excellent catalytic activity. When applied to a solid oxide electrolyzer, it has a high current density and low polarization resistance, and can meet the actual application requirements of CO2 electroreduction.

[0006] To solve the above technical problems, in the first aspect of the present invention, a porous electrode material is provided. The chemical general formula of the porous electrode material is: Sr2Fe 1.5 Mo 0.5-x W x O6- δ , where: x represents the molar fraction, and the value range of x is 0 < x ≤ 0.5; δ represents the number of oxygen vacancies, and 0 ≤ δ < 1.

[0007] The present invention uses Sr2Fe 1.5 Mo 0.5 ​Using O6 perovskite as the matrix, partial substitution of Mo with W doping enhances the material's CO2 adsorption capacity and electrochemical performance. Specifically, W has a valence of +6, higher than that of Fe and Mo. Its incorporation triggers charge compensation, increasing oxygen vacancies and thus improving the material's ionic conductivity. Simultaneously, W exhibits high electronegativity, exceeding that of Fe and Mo. Its incorporation forms stronger WO bonds, inhibiting grain aggregation at high temperatures and improving the material's resistance to sintering. Furthermore, W's smaller ionic radius compared to Mo leads to cell volume shrinkage and smaller particle size, further enhancing the material's catalytic activity.

[0008] In some embodiments of the present invention, the value of x ranges from 0.1 to 0.5. For example, x can take values ​​of 0.1, 0.2, 0.3, 0.4, and 0.5, including but not limited to the listed values. Other unlisted values ​​within this range also apply. Studies have found that this doping amount is beneficial for maintaining the integrity of the perovskite structure. Simultaneously, the number of oxygen vacancies, determined by the elemental valence equilibrium and the preparation process, is used to promote CO2 adsorption and activation.

[0009] A second aspect of the present invention provides a method for preparing the above-mentioned porous electrode material, comprising the following steps: (1) Dissolve soluble strontium salt, soluble iron salt, soluble molybdate and soluble tungsten salt in water according to the stoichiometric ratio of the general chemical formula to obtain a mixed solution; (2) Add a complexing agent to the mixed solution and adjust the pH value to form a metal complex solution; (3) The metal complex solution is heated to form a gel; (4) The gel is calcined to obtain the porous electrode material.

[0010] In some embodiments of the present invention, in step (1), the soluble strontium salt is selected from at least one of strontium nitrate, strontium chloride, strontium carbonate and hydrates of the above substances; preferably strontium nitrate.

[0011] In some embodiments of the present invention, the soluble iron salt is selected from at least one of ferric chloride, ferric nitrate, ferric sulfate, and hydrates of the above substances; preferably ferric nitrate nonahydrate.

[0012] In some embodiments of the present invention, the soluble molybdate is selected from at least one of ammonium molybdate, ammonium heptamolybdate, and hydrates of the above substances; preferably ammonium molybdate tetrahydrate.

[0013] In some embodiments of the present invention, the soluble tungsten salt is selected from at least one of tungsten nitrate, ammonium tungstate, and hydrates of the above substances; preferably tungsten nitrate.

[0014] In some embodiments of the present invention, in step (1), the concentration of the soluble strontium salt in the mixed solution is (1-10) g: 100 mL; preferably, the concentration of the soluble strontium salt is (1-5) g: 100 mL; more preferably, the concentration of the soluble strontium salt is (1-3) g: 100 mL.

[0015] In some embodiments of the present invention, in step (1), the water is deionized water.

[0016] In some embodiments of the present invention, in step (2), the complexing agent includes citric acid (CA) and ethylenediaminetetraacetic acid (EDTA).

[0017] In some embodiments of the present invention, the molar ratio of citric acid to ethylenediaminetetraacetic acid is (1-3):1; preferably, the molar ratio of citric acid to ethylenediaminetetraacetic acid is (1-2):1.

[0018] In some embodiments of the present invention, the molar ratio of the ethylenediaminetetraacetic acid to the sum of metal cations in the mixed solution is (0.5-1.5):1; preferably, the molar ratio of the ethylenediaminetetraacetic acid to the sum of metal cations in the mixed solution is (0.8-1.2):1.

[0019] In some embodiments of the present invention, the pH value is adjusted to 7-8 using ammonia to facilitate the formation of a stable metal complex solution.

[0020] In some embodiments of the present invention, in step (3), the heating temperature is 120-300°C.

[0021] In some embodiments of the present invention, in step (3), the heating process is as follows: the metal complex solution is first stirred at 120-180°C for 2-5 hours, and then heated to 200-300°C to evaporate the water until a uniform gel is formed.

[0022] In some embodiments of the present invention, in step (4), the calcination temperature is 1000-1200℃ and the calcination time is 8-12 hours; preferably, the calcination temperature is 1050-1150℃ and the calcination time is 9-11 hours. A third aspect of the present invention provides an electrode comprising an electrolyte sheet and a conductive film layer formed on the surface of the electrolyte sheet, wherein the raw materials for preparing the conductive film layer include the aforementioned porous electrode material.

[0023] A fourth aspect of the present invention provides a method for preparing the above-described electrode, comprising the following steps: A porous electrode material is made into an electrode slurry, which is then coated onto an electrolyte sheet to form a conductive film layer. The slurry is then subjected to heat treatment to obtain the electrode.

[0024] In some embodiments of the present invention, the preparation process of the electrode slurry includes the following steps: adding porous electrode material to a terpineol solution containing 6-10 wt% ethyl cellulose, stirring evenly, and obtaining the electrode slurry.

[0025] In some embodiments of the present invention, the mass ratio of the terpineol solution of ethyl cellulose to the porous electrode material is (0.5-1.5):1.

[0026] In some embodiments of the present invention, the electrolyte sheet includes a substrate, the surface of which is coated with a transition layer, the transition layer being lanthanum-doped cerium oxide (LDC), and the substrate being strontium magnesium co-doped lanthanum gallate (LSGM).

[0027] In some embodiments of the present invention, the thickness of the conductive film layer is 10-20 μm.

[0028] In some embodiments of the present invention, the heat treatment refers to calcination at a temperature of 1000-1200°C for 2-5 hours; preferably, the heat treatment refers to calcination at a temperature of 1050-1150°C for 3-4 hours.

[0029] A fifth aspect of the present invention provides a solid oxide electrolytic cell, comprising the electrodes described above, or comprising electrodes prepared by the methods described above.

[0030] In some embodiments of the present invention, the electrode serves as the cathode of a solid oxide electrolytic cell.

[0031] Compared with the prior art, the above-described technical solution of the present invention has at least the following technical effects or advantages: (1) The present invention utilizes Sr2Fe 1.5 Mo 0.5 By doping some Mo with W in O6 perovskite material, and utilizing W's higher valence state and electronegativity compared to Fe and Mo, as well as its smaller ionic radius compared to Mo, a porous electrode material was designed. This electrode material not only exhibits high CO2 adsorption capacity but also combines high-temperature stability with high catalytic activity.

[0032] (2) The porous electrode material of the present invention is prepared by sol-gel method. The preparation process is simple and feasible, and the W doping modification process is controllable. It is highly compatible with the existing perovskite material preparation method and does not require additional complex equipment. When the prepared porous electrode material is applied to oxide solid electrolysis cell, it effectively improves the current density of SOEC electrolysis of CO2 and reduces the polarization impedance of the material, thereby improving the electrochemical performance of SOEC. It can meet the core requirements of SOEC industrialization for "high current and low cost" and has good application prospects. Attached Figure Description

[0033] Figure 1 XRD patterns of the porous electrode materials prepared in Examples 1-3 and Comparative Example 1; Figure 2 SEM image of the porous electrode material prepared in Example 3; Figure 3 SEM image of the porous electrode material prepared in Comparative Example 1; Figure 4 SEM image of the porous electrode material prepared in Comparative Example 2; Figure 5 CO2-TPD diagrams of the porous electrode materials prepared in Example 3 and Comparative Example 1; Figure 6 Thermogravimetric diagrams of the porous electrode materials prepared in Example 3 and Comparative Example 1; Figure 7 EIS images of the porous electrode materials prepared in Examples 1-3 and Comparative Example 1 at 850°C; Figure 8 LSV curves of SOEC assembled from cathodes prepared in Examples 1-3 and Comparative Example 1 at 850°C; Figure 9 The LSV curve of the SOEC assembled from the cathodes prepared in Example 1 and Comparative Example 2 at 850°C is shown. Detailed Implementation

[0034] The present invention will now be described in detail with reference to embodiments to facilitate understanding of the invention by those skilled in the art. It is particularly important to note that the embodiments are merely illustrative of the invention and should not be construed as limiting the scope of protection of the invention. Non-essential improvements and adjustments made to the invention by those skilled in the art based on the above description should still fall within the scope of protection of the invention. Furthermore, all raw materials mentioned below, unless otherwise specified, are commercially available products; all process steps or preparation methods not mentioned in detail are process steps or preparation methods known to those skilled in the art.

[0035] Example 1 A porous electrode material with the chemical formula: Sr2Fe1.5 Mo 0.4 W 0.1 O6. The preparation method of this porous electrode material includes the following steps: (1) According to the chemical formula Sr2Fe 1.5 Mo 0.4 W 0.1 Based on the stoichiometry of O6, weigh out 6.772g of Sr(NO3)2 and 9.696g of Fe(NO3)3. 9H2O), 1.131g (NH4)6Mo7O 24 4H2O) and 0.682g W(NO3)6 were dissolved in 500mL of deionized water and stirred until completely dissolved to form a mixed solution of metal nitrates; (2) Add 18.443g CA and 18.703g EDTA to the mixed solution obtained in step (1), wherein the ratio of the number of moles of CA to the total number of moles of metal cations in the mixed solution is 1.5:1, and the ratio of the number of moles of EDTA to the total number of moles of metal cations in the mixed solution is 1:1. Stir until completely dissolved; then add ammonia dropwise to adjust the pH of the mixed solution to 7-8 to form a stable metal complex solution. (3) The metal complex solution obtained in step (2) was stirred at 150°C for 3 hours, and then heated to 250°C to evaporate the water until a uniform gel was formed. (4) Transfer the gel obtained in step (2) to a ceramic container, continue heating until it spontaneously combusts, collect the powder after spontaneous combustion, place it in a muffle furnace and calcine at 1100°C for 10 hours, and after natural cooling, obtain the SFMW-based perovskite structure oxide powder of this embodiment, denoted as SFMW. 0.1 Material.

[0036] A method for preparing a cathode material includes the following steps: 1) After grinding the porous electrode material prepared in this embodiment, add a terpineol solution containing 8 wt.% ethyl cellulose, wherein the mass ratio of the terpineol solution of ethyl cellulose to the porous electrode material is 1:1, and stir evenly to prepare an electrode slurry; 2) The electrode paste obtained in step 1) is uniformly coated onto the strontium magnesium co-doped lanthanum gallate (LSGM) electrolyte sheet coated with a lanthanum doped cerium oxide (LDC) transition layer to form an electrode film with a thickness of 10-20 μm. 3) Place the electrolyte sheet coated with electrode slurry obtained in step 1) into a muffle furnace and calcine it at 1100℃ for 3 hours. After cooling, the cathode material is obtained.

[0037] Example 2 A porous electrode material with the chemical formula: Sr2Fe1.5 Mo 0.2 W 0.3 O6. The preparation method of this porous electrode material includes the following steps: (1) According to the chemical formula Sr2Fe 1.5 Mo 0.2 W 0.3 Based on the stoichiometry of O6, weigh out 6.772g of Sr(NO3)2 and 9.696g of Fe(NO3)3. 9H2O), 0.565g (NH4)6Mo7O 24 4H2O) and 2.045g W(NO3)6 were dissolved in 500mL of deionized water and stirred until completely dissolved to form a mixed solution of metal nitrates; (2) Add 18.443g CA and 18.703g EDTA to the mixed solution obtained in step (1), wherein the ratio of the number of moles of CA to the total number of moles of metal cations in the mixed solution is 1.5:1, and the ratio of the number of moles of EDTA to the total number of moles of metal cations in the mixed solution is 1:1. Stir until completely dissolved; then add ammonia dropwise to adjust the pH of the mixed solution to 7-8 to form a stable metal complex solution. (3) The metal complex solution obtained in step (2) was stirred at 150°C for 3 hours, and then heated to 250°C to evaporate the water until a uniform gel was formed. (4) Transfer the gel obtained in step (2) to a ceramic container, continue heating until it spontaneously combusts, collect the powder after spontaneous combustion, place it in a muffle furnace and calcine at 1100°C for 10 hours, and after natural cooling, obtain the SFMW-based perovskite structure oxide powder of this embodiment, denoted as SFMW. 0.3 Material.

[0038] The preparation method of the cathode material is the same as that in Example 1.

[0039] Example 3 A porous electrode material with the chemical formula: Sr2Fe 1.5 W 0.5 O6. The preparation method of this porous electrode material includes the following steps: (1) According to the chemical formula Sr2Fe 1.5 W 0.5 Based on the stoichiometry of O6, weigh out 6.772g of Sr(NO3)2 and 9.696g of Fe(NO3)3. 9H2O) and 3.408g W(NO3)6 were dissolved in 500mL of deionized water and stirred until completely dissolved to form a mixed solution of metal nitrates; (2) Add 18.443g CA and 18.703g EDTA to the mixed solution obtained in step (1), wherein the ratio of the number of moles of CA to the total number of moles of metal cations in the mixed solution is 1.5:1, and the ratio of the number of moles of EDTA to the total number of moles of metal cations in the mixed solution is 1:1. Stir until completely dissolved; then add ammonia dropwise to adjust the pH of the mixed solution to 7-8 to form a stable metal complex solution. (3) The metal complex solution obtained in step (2) was stirred at 150°C for 3 hours, and then heated to 250°C to evaporate the water until a uniform gel was formed. (4) Transfer the gel obtained in step (2) to a ceramic container, continue heating until it spontaneously combusts, collect the powder after spontaneous combustion, place it in a muffle furnace and calcine at 1100°C for 10 hours, and after natural cooling, obtain the SFW-based perovskite structure oxide powder of this embodiment, denoted as SFW. 0.5 Material.

[0040] The preparation method of the cathode material is the same as that in Example 1.

[0041] Comparative Example 1 A porous electrode material with the chemical formula: Sr2Fe 1.5 Mo 0.5 O6. The preparation method of this porous electrode material includes the following steps: (1) According to the chemical formula Sr2Fe 1.5 Mo 0.5 Based on the stoichiometry of O6, weigh out 6.772g of Sr(NO3)2 and 9.696g of Fe(NO3)3. 9H2O), 1.410g (NH4)6Mo7O 24 Dissolve 4H2O in 500mL of deionized water and stir until completely dissolved to form a mixed solution of metal nitrates; (2) Add 18.443g CA and 18.703g EDTA to the mixed solution obtained in step (1), wherein the ratio of the number of moles of CA to the total number of moles of metal cations in the mixed solution is 1.5:1, and the ratio of the number of moles of EDTA to the total number of moles of metal cations in the mixed solution is 1:1. Stir until completely dissolved; then add ammonia dropwise to adjust the pH of the mixed solution to 7-8 to form a stable metal complex solution. (3) The metal complex solution obtained in step (2) was stirred at 150°C for 3 hours, and then heated to 250°C to evaporate the water until a uniform gel was formed. (4) Transfer the gel obtained in step (2) to a ceramic container, continue heating until it spontaneously combusts, collect the powder after spontaneous combustion, place it in a muffle furnace and calcine at 1100℃ for 10 hours, and after natural cooling, obtain the SFM-based perovskite structure oxide powder of this comparative example, which is denoted as SFM material.

[0042] The preparation method of the cathode material is the same as that in Example 1.

[0043] Comparative Example 2 A porous electrode material with the chemical formula: Sr2Fe 1.5 Mo 0.4 Ga 0.25 O6. The preparation method of this porous electrode material includes the following steps: (1) According to the chemical formula Sr2Fe 1.5 Mo 0.4 Ga 0.1 Based on the stoichiometry of O6, weigh out 6.772g of Sr(NO3)2 and 9.696g of Fe(NO3)3. 9H2O), 1.131g (NH4)6Mo7O 24 4H2O) and 0.785g Ga(NO3)3 were dissolved in 500mL of deionized water and stirred until completely dissolved to form a mixed solution of metal nitrates; (2) Add 18.443g CA and 18.703g EDTA to the mixed solution obtained in step (1), wherein the ratio of the number of moles of CA to the total number of moles of metal cations in the mixed solution is 1.5:1, and the ratio of the number of moles of EDTA to the total number of moles of metal cations in the mixed solution is 1:1. Stir until completely dissolved; then add ammonia dropwise to adjust the pH of the mixed solution to 7-8 to form a stable metal complex solution. (3) The metal complex solution obtained in step (2) was stirred at 150°C for 3 hours, and then heated to 250°C to evaporate the water until a uniform gel was formed. (4) Transfer the gel obtained in step (2) to a ceramic container, continue heating until it spontaneously combusts, collect the powder after spontaneous combustion, place it in a muffle furnace and calcine at 1100℃ for 10 hours, and after natural cooling, obtain the SFMG-based perovskite structure oxide powder of this comparative example, denoted as SFMGa. 0.25 Material.

[0044] The preparation method of the cathode material is the same as that in Example 1.

[0045] Material characterization and performance testing Figure 1The images show the XRD patterns of the porous electrode materials prepared in Examples 1-3 and Comparative Example 1. The horizontal axis 2θ represents the diffraction angle, and the vertical axis Intensity represents the intensity of the diffraction peak. Figure 1 It can be seen that as the W doping concentration increases, the main peak shifts towards the elevation angle, resulting in a shrinkage of the surface cell volume.

[0046] Figure 2-4 The images show the SEM morphology of the porous electrode materials prepared in Example 3, Comparative Example 1, and Comparative Example 2 at different magnifications. Figure 2 It is known that the SFW prepared in Example 3 0.5 The electrode material has a loose and porous structure, and the small particle size of the material is conducive to the adsorption and diffusion of CO2.

[0047] Will Figure 2 and Figure 3 and Figure 4 A comparison shows that the SFM electrode materials prepared in Comparative Example 1 and Comparative Example 2 have better comparability than SFMGa. 0.25 The powder particles of the material are significantly larger than those of the SFW prepared in Example 3. 0.5 Electrode materials, and only SFW 0.5 The electrode material has a circular porous structure, proving that W doping is effective in controlling its morphology.

[0048] Figure 5 The CO2-TPD diagrams of the porous electrode materials prepared in Example 3 and Comparative Example 1 are shown. The horizontal axis represents temperature (Temperature) and peak intensity (Intensity). The detection process is as follows: A 0.1 g sample of porous electrode material was weighed and placed in a quartz reaction tube. Pure He was introduced at a flow rate of 50 mL / min, and the temperature was continuously increased to 300 °C for sample pretreatment. After cooling to room temperature, the gas was switched to a CO2 and He mixture with a volume ratio of 1:9. The flow rate was kept constant, and the mixture was continuously introduced for 120 min for adsorption. Subsequently, the temperature was increased to 950 °C at a rate of 10 °C / min, and the desorption program was started simultaneously.

[0049] Depend on Figure 5 It can be seen that the SFW prepared in Example 3 0.5 The high-temperature and low-temperature peak areas of the electrode material are larger than those of the SFM electrode material prepared in Comparative Example 1, indicating that SFW 0.5 The material has a higher CO2 adsorption capacity than SFM.

[0050] Figure 6 The thermogravimetric (TGA) plots for the porous electrode materials prepared in Example 3 and Comparative Example 1 are shown, with Temperature on the horizontal axis representing temperature and Weight representing weight loss. Figure 6 It can be seen that as the temperature rises to 850℃, the SFMW prepared in Example 1...0.1 The weight loss of the electrode material was 3.18%, while the weight loss of the SFM electrode material prepared in Comparative Example 1 was only 1.32%, which indicates that SFMW... 0.1 There are more oxygen vacancies in the material.

[0051] Figure 7 The following are EIS images of the porous electrode materials prepared in Examples 1-3 and Comparative Example 1 at 850°C. The detection process is as follows: Porous electrode material samples were fabricated into symmetrical electrodes and assembled into a sealed electrolyte-supported test cell. The cell was placed in a tube furnace and heated to 850℃ at a heating rate of 5℃ / min and held at that temperature for 30 min to ensure uniform and stable cell temperature. Using an electrochemical workstation, under open-circuit voltage conditions, the test frequency range was set to 100kHz-0.1Hz, and the AC perturbation amplitude was 10mV. Impedance response signals at different frequencies were recorded. The impedance spectrum data were fitted and analyzed using ZView software to obtain a graph with the real impedance (Z′) as the abscissa and the imaginary impedance (Z′) as the scalar axis. The Nyquist plot with Z′′ as the ordinate yields... Figure 7 The EIS spectrum shown.

[0052] Depend on Figure 7 It can be seen that, under the test conditions of 850℃ and 50%CO-50%CO2 open circuit voltage in EIS testing, the SFW prepared in Example 3 can be observed to be... 0.5 The electrode material, i.e., after complete W substitution, has an RP value of 0.41 Ω cm. 2 Compared to the 1.63 Ω cm of the SFM electrode material prepared in Comparative Example 1 2 This reduced the Ω cm by 1.22. 2 This demonstrates that W doping reduces the polarization impedance of the material.

[0053] SOEC single cells were assembled using cathodes prepared in Examples 1-3 and Comparative Examples 1-2, respectively. The assembly process is as follows: First, select a dense La material of suitable size. 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O3 δ (LSGM) electrolyte sheets were ultrasonically cleaned sequentially with deionized water and anhydrous ethanol for 30 minutes each, then dried for later use; the anode was made of La. 0.8 Sr 0.2 Co 0.2 Fe 0.8 O3 δ -Ce 0.8 Sm 0.2 O2 δ The (LSCF-SDC) composite material was prepared by mixing its powder with an organic binder and terpineol in a certain proportion, ball milling for 24 hours to prepare a uniform anode slurry, and then coating it onto one side of an LSGM electrolyte sheet by screen printing, with the coating area controlled at 1 cm². It was then placed in a muffle furnace and heated to 1100°C at a rate of 5°C / min, and calcined at that temperature for 2 hours. After natural cooling, a dense anode layer with a thickness of approximately 20 μm was formed. The cathode used was the cathode-SDC composite material prepared in Examples 1-3 and Comparative Examples 1-2, using the same slurry. The cathode slurry was prepared by a process (powder + binder + terpineol, ball milling for 12 h), and coated on the other side of the LSGM electrolyte sheet by screen printing. The coating area was the same as that of the anode layer. The cathode was heated to 1000℃ at 5℃ / min and calcined at a constant temperature for 2 h. After cooling, a porous cathode layer with a thickness of about 15 μm was obtained. Finally, Ag slurry was coated on the anode and cathode surfaces respectively, and Ag wire was welded as the current collecting electrode. The assembled battery was placed in a 120℃ drying oven for 2 h to remove residual organic matter, and the SOEC single cell assembly was completed.

[0054] Figure 8 and Figure 9 The figures show the LSV curves of SOEC single cells assembled from cathodes prepared in Examples 1-3 and Comparative Examples 1-2 at 850℃. The horizontal axis represents the applied potential, and the vertical axis represents the current density. The detection process is as follows: The cathode materials prepared in Examples 1-3 and Comparative Examples 1-2 were assembled into LSGM electrolyte-supported SOEC single cells. The cells were placed in a tube furnace, and high-purity argon was introduced as a protective atmosphere. The temperature was increased to 850℃ at a rate of °C / min and held at that temperature for 30 min to ensure uniform and stable cell temperature. Linear sweep voltammetry (LSV) tests were performed on the cells using an electrochemical workstation. During the test, the cathode side was controlled to have a CO2 atmosphere and the anode side to have an air atmosphere. The scan range was set to 0-1.8V, and the scan rate was 5mV / s. The current density corresponding to different applied potentials was recorded in real time, and the results were obtained. Figure 8 and Figure 9 The LSV curve of SOEC at 850℃ is shown.

[0055] Depend on Figure 8 It can be seen that, under the test conditions of 850℃ and 1.5V pure CO2 atmosphere, the SFMW prepared in Example 1... 0.1 The cathode fabricated from the electrode material achieved a current density of 3.70 A / cm². -2 The cathode prepared from the SFM electrode material in Comparative Example 1 had a current density of 2.25 A / cm². -2 An increase of 64%. Figure 9It can be seen that, under the conditions of 850℃ and 1.5V, the SFMW prepared in Example 1... 0.1 The cathode fabricated from the electrode material exhibits a current density of 3.70 A cm⁻¹. -2 Significantly larger than the SFMGa prepared in Comparative Example 2 0.25 The cathode fabricated from the electrode material has a current density of 3.32 A cm⁻¹. -2 .

[0056] For those skilled in the art, several simple deductions or substitutions can be made without departing from the inventive concept, without requiring creative effort. Therefore, any simple improvements made to this invention by those skilled in the art based on the disclosure of this invention should be within the scope of protection of this invention. The above embodiments are preferred embodiments of this invention, and all processes similar to this invention and equivalent changes should fall within the scope of protection of this invention.

Claims

1. A porous electrode material, characterized in that, The chemical general formula of the porous electrode material is: Sr2Fe 1.5 Mo 0.5- x W x O6- δ , where: x represents the mole fraction, and the value range of x is 0 < x ≤ 0.5; δ represents the number of oxygen vacancies, and 0 ≤ δ < 1.

2. The porous electrode material according to claim 1, characterized in that, The range of x is: 0.1≤x≤0.

5.

3. A method for preparing a porous electrode material as described in any one of claims 1-2, characterized in that, Includes the following steps: (1) Dissolve soluble strontium salt, soluble iron salt, soluble molybdate and soluble tungsten salt in water according to the stoichiometric ratio of the general chemical formula to obtain a mixed solution; (2) Add a complexing agent to the mixed solution and adjust the pH value to form a metal complex solution; (3) The metal complex solution is heated to form a gel; (4) The gel is calcined to obtain the porous electrode material.

4. The method for preparing the porous electrode material according to claim 3, characterized in that, In step (1), the soluble strontium salt is selected from at least one of strontium nitrate, strontium chloride, strontium carbonate, and hydrates of the above substances; And / or, the soluble iron salt is selected from at least one of ferric nitrate, ferric chloride, ferric sulfate, and hydrates of the above substances; And / or, the soluble molybdate is selected from at least one of ammonium molybdate, ammonium heptamolybdate, and hydrates of the above substances; And / or, the soluble tungsten salt is selected from at least one of tungsten nitrate, ammonium tungstate, and hydrates of the above substances.

5. The method for preparing porous electrode material according to claim 3, characterized in that, In step (2), the complexing agent includes citric acid and ethylenediaminetetraacetic acid, the molar ratio of citric acid and ethylenediaminetetraacetic acid is (1-3):1, and the molar ratio of ethylenediaminetetraacetic acid to the sum of metal cations in the mixed solution is (0.5-1.5):1; And / or, the pH value is adjusted to 7-8 using ammonia.

6. The method for preparing the porous electrode material according to claim 3, characterized in that, In step (3), the heating temperature is 120-300℃; And / or, in step (4), the calcination temperature is 1000-1200℃ and the calcination time is 8-12 hours.

7. An electrode, characterized in that, It includes an electrolyte sheet and a conductive film layer formed on the surface of the electrolyte sheet, wherein the raw materials for preparing the conductive film layer include the porous electrode material according to any one of claims 1-2.

8. A method for preparing an electrode as described in claim 7, characterized in that, Includes the following steps: A porous electrode material is made into an electrode slurry, which is then coated onto an electrolyte sheet to form a conductive film layer. The slurry is then subjected to heat treatment to obtain the electrode.

9. The method for preparing the electrode according to claim 8, characterized in that, The heat treatment refers to calcination at 1000-1200℃ for 2-5 hours.

10. A solid oxide electrolytic cell, characterized in that, It includes the electrode as described in claim 7, or the electrode prepared by the method described in claim 8 or 9.

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