An oxygen-enriched defective iron-based perovskite-type oxide material, a method for preparing the same, and an application thereof in a solid oxide electrolysis cell

Abstract

The present application relates to the technical field of solid oxide electrolysis cell, and particularly relates to an oxygen-rich defect iron-based perovskite oxide material, a preparation method thereof and application of the material in a solid oxide electrolysis cell. The method adopts a flash Joule heat ultrafast synthesis process, a precursor is rapidly heated in several seconds to several tens of seconds and perovskite phase formation is completed by instant high current, and then cooling is performed to obtain an oxygen-rich defect iron-based perovskite oxide material. The process flow is simple, the preparation period is short, and a material structure with small particle size and uniform distribution is obtained. The ultrafast non-equilibrium heat treatment process introduces stable oxygen defects and structural distortion in the perovskite material, and improves the electronic structure and electrochemical reaction kinetics performance. The material is used as a solid oxide electrolysis cell cathode, and under high-temperature CO2 electrolysis conditions, a high electrolysis current density and good long-term operation stability can be realized, and the material has a good engineering application prospect.

Description

Technical Field

[0001] This invention relates to the field of solid oxide electrolytic cell technology, and in particular to an oxygen-rich defective iron-based perovskite oxide material, its preparation method, and its application in solid oxide electrolytic cells. Background Technology

[0002] Iron-based perovskite oxides (ABO) 3-δ Iron-based perovskite materials (with rare earth elements or alkaline earth metals at the A site and metallic Fe at the B site) are widely used as cathode materials in solid oxide electrolysis cells (SOECs) due to their excellent electron-ion mixed conductivity, tunable oxygen defect concentration, and high thermochemical stability. Especially in high-temperature CO2 electrolysis, iron-based perovskite materials can simultaneously promote oxygen ion transport and CO2 surface adsorption / activation processes, demonstrating significant application potential.

[0003] In existing technologies, iron-based perovskite oxides are typically prepared via high-temperature solid-state reaction methods or liquid-phase chemical methods such as sol-gel. Solid-state methods generally suffer from problems such as high sintering temperatures, long reaction times (typically ≥5 h), large and unevenly distributed particle sizes, and limited oxygen defect concentrations. While liquid-phase methods such as sol-gel improve elemental mixing uniformity to some extent, their preparation processes are complex and time-consuming, and grain coarsening and oxygen defect recovery are still unavoidable during high-temperature calcination.

[0004] Furthermore, in iron-based perovskite materials prepared by existing methods, the Fe-O octahedral structure often approaches thermodynamic equilibrium, limiting the control space for the valence and spin states (high spin / low spin) of Fe. This makes it difficult to achieve deep optimization of electrocatalytic activity at the electronic structure level, thus restricting its electrolytic current density (≥1.0 A cm⁻¹) under high-temperature conditions (≥800 °C). -2 Improved performance and stability under long-term (≥100 h) SOEC operating conditions.

[0005] Therefore, developing a novel preparation method that can achieve rapid phase formation of perovskite in a very short time, while introducing high concentrations of non-equilibrium oxygen defects and effectively controlling the electronic structure and spin state of Fe is of great significance for improving the electrolytic performance of iron-based perovskite materials in SOEC cathodes. Summary of the Invention

[0006] The purpose of this invention is to address the aforementioned shortcomings of the prior art by proposing a more efficient and superior oxygen-rich defect iron-based perovskite oxide material, its preparation method, and its application in solid oxide electrolytic cells.

[0007] The first objective of this invention is to provide a method for preparing an oxygen-rich defect iron-based perovskite oxide material, wherein the general chemical formula of the iron-based perovskite oxide material is ABO. 3-δ Where A is one or more of La, Pr, Nd, Sm, Gd, Sr, Ca, and Ba, and B is Fe, with 3 > δ > 0; the preparation includes the following steps: S1: Provide a metal source at site A and an iron source at site B according to the stoichiometric ratio. Add the metal source to a deionized aqueous solution in sequence, mix and stir, add the complex, adjust the pH of the solution to 7-8 and perform hydrothermal treatment to obtain the precursor gel. S2: The precursor gel is precalcined to obtain a fluffy black intermediate, which is ball-milled to obtain a black powder. The black powder is then annealed to remove residual carbon and organic matter, thus obtaining the precursor powder.

[0008] S3: Add a conductive additive to the precursor powder and mix thoroughly to obtain a composite precursor powder; S4: The composite precursor powder is placed in a molybdenum boat or tungsten boat and subjected to flash Joule heat treatment under an inert atmosphere, a low oxygen partial pressure atmosphere or a vacuum atmosphere, followed by low-temperature annealing to obtain an oxygen-rich defect iron-based perovskite oxide material.

[0009] Furthermore, the specific parameters for flash Joule heat treatment are: a set temperature of 900-1200 ℃ and a heating rate of 100-150 K s. -1 The current is 200-500 A, and the heat preservation time is 10-50 s.

[0010] Furthermore, the general chemical formula of the iron-based perovskite oxide is A. x A' (1-x) FeO 3-δ Where A = one of La, Pr, Nd, Sm, and Gd, A' = one of Sr, Ca, and Ba, and x = 0.2~0.8.

[0011] Furthermore, in step S2, the black intermediate is pre-calcined at 200-300 °C for 2-5 h and then annealed at 600 °C for 2 h.

[0012] Furthermore, the metal source and iron source are nitrates, acetates, chlorides, or any combination thereof; the complexing agent is citric acid and ethylenediaminetetraacetic acid.

[0013] Furthermore, the conductive additive is selected from carbon black, graphite, graphene, carbon nanotubes or any combination thereof, and its addition amount is 10%-15% of the precursor mass.

[0014] Furthermore, the inert atmosphere is argon or nitrogen; the low oxygen partial pressure atmosphere is a protective atmosphere with an oxygen volume fraction of no more than 1%.

[0015] Furthermore, in step S3, the low-temperature annealing treatment is carried out at a temperature of 500-600 ℃ for a time of 25-35 min.

[0016] A second objective of the present invention is to provide an oxygen-rich defective iron-based perovskite oxide material, wherein the material is prepared by the preparation method described in any one of claims 1-8.

[0017] The second objective of this invention is to provide an application of the oxygen-rich defect iron-based perovskite oxide material as described above in a solid oxide electrolytic cell, used as the cathode of the solid oxide electrolytic cell for CO2 electrolysis, H2O electrolysis, or CO2-H2O co-electrolysis.

[0018] The present invention has the following beneficial effects: 1. Compared with conventional preparation processes, the flash Joule heating ultrafast synthesis process can complete the perovskite phase formation within tens of seconds, significantly shortening the material preparation cycle and reducing energy consumption; 2. The material prepared by this invention has smaller particle size and more uniform distribution, generating a high surface area nanostructure, which is beneficial to increasing the specific surface area of ​​perovskite oxide materials and improving electrode reactivity; 3. By utilizing the ultra-high heating rate and rapid cooling process generated by flash Joule heating, a non-equilibrium oxygen defect structure is constructed in iron-based perovskite. The introduction of high concentration of non-equilibrium oxygen defects into the material induces distortion of Fe-O bond length and bond angle, thereby regulating the valence distribution and spin configuration of Fe, optimizing the electronic structure, and improving the catalytic reduction ability. 4. When the oxygen-defect-rich perovskite material prepared by this invention is used as a SOEC cathode material, it exhibits higher current density, lower polarization impedance and better long-term stability in high-temperature CO2 or H2O electrolysis. Attached Figure Description

[0019] Figure 1 The perovskite oxide La prepared by flash evaporation Joule heating ultrafast synthesis in Example 1 0.5 Sr 0.5 FeO 3-δ A flowchart of the assembly of powder (abbreviated as JH-LSF) into SOEC electrolysis test; Figure 2 JH-LSF powder prepared by flash Joule heating in Example 1 and La prepared by conventional sol-gel method 0.5 Sr 0.5 FeO 3-δ XRD pattern of powder (abbreviated as LSF); Figure 3a Here is a SEM image of the JH-LSF powder from Example 1; Figure 3b Here is a SEM image of the LSF powder in Example 1; Figure 3c This is an elemental scan distribution diagram of the JH-LSF powder in Example 1; Figure 4a This is a comparison of the energy spectrum of surface iron elements between JH-LSF powder and LSF powder in Example 1. Figure 4b This is a comparison of the energy spectrum of oxygen elements on the surface of JH-LSF powder and LSF powder in Example 1. Figure 5a The images show the FTIR spectra of JH-LSF powder and LSF powder in Example 1. Figure 5b The images show the Raman spectra of JH-LSF powder and LSF powder in Example 1 of this embodiment. Figure 6a EIS curves of JH-LSF powder and LSF powder in this embodiment at different temperatures in a CO2:CO = 1:1 atmosphere; Figure 6b The polarization resistance of JH-LSF powder and LSF powder prepared in Example 1 at different temperatures in an atmosphere of CO2:CO = 1:1. Figure 7a The current-voltage diagrams for direct CO2 electrolysis using JH-LSF powder as an SOEC cathode in this embodiment 1 at different temperatures are shown. Figure 7b Current-voltage diagrams for direct CO2 electrolysis using LSF powder as SOEC cathode at different temperatures; Figure 8a EIS curves of full cells at different temperatures using JH-LSF powder prepared in Example 1 as SOEC cathode; Figure 8b EIS curves of full cells with LSF powder as SOEC cathode at different temperatures; Figure 9a The results show the stability test of JH-LSF powder as SOEC cathode in Example 1 at 800 °C and 1.3 V electrolysis voltage. Figure 9b The images show SEM images of the cathode and electrolyte cross sections after the LH-LSF powder of this embodiment was used as the SOEC cathode for stability testing. Detailed Implementation

[0020] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0021] Example 1: According to the chemical formula La 0.5 Sr 0.5 FeO 3-δ Sr(CH3COO)2, Fe(NO3)2·9H2O, and La(NO3)3·6H2O were weighed out according to stoichiometric ratio and dissolved sequentially in 100 mL of deionized water. The solution was continuously stirred magnetically at room temperature to form a homogeneous and clear mixed salt solution. Citric acid and ethylenediaminetetraacetic acid (EDTA) were added as complexing agents, and the molar ratio of total metal ions to citric acid to EDTA was controlled at 1:1:1.5. Subsequently, ammonia was added dropwise to adjust the pH of the solution to 7-8, resulting in a clear, transparent, and stable precursor solution. The precursor solution was transferred to an evaporating dish and placed in a constant temperature water bath at 80 °C for 10 h to obtain a gel-like substance.

[0022] The obtained gel-like material was calcined in an electronic universal furnace at a temperature of 200-300 °C to obtain a black, fluffy intermediate product, which was then thoroughly ground to obtain a black powder. The black powder was then placed in a muffle furnace and annealed at a heating rate of 3 °C / min to 600 °C for 2 h in a static air atmosphere to remove residual carbon and organic matter, thus obtaining the precursor powder.

[0023] Carbon black, a conductive additive, is added to the original precursor powder at 10% of its mass and mixed thoroughly to improve the overall conductivity of the material under energized conditions, thus obtaining a composite precursor powder.

[0024] The composite precursor powder was uniformly distributed in a molybdenum boat (100×20×0.2mm) within a flash Joule heating apparatus. The chamber was evacuated and then argon gas was introduced. This process was repeated three times. No additional gas was introduced during the entire heating process, and it was completed in a static argon atmosphere without any gas flow. The temperature was monitored in real time by detecting the infrared radiation energy emitted from the object's surface. The calcination temperature was adjusted by controlling the applied current. The set temperature was 1000 ℃, the current was 300 A, the holding time was 30 s, and the heating rate was 100-150 K s. -1 After rapid sintering at 1000-1100 °C and flash joule heating, the product is subjected to low-temperature annealing in a muffle furnace and treated at 500 °C for 30 min to obtain La. 0.5 Sr 0.5 FeO 3-δ (abbreviated as JH-LSF) powder.

[0025] The cathode material JH-LSF prepared above and 7.5 wt.% ethyl cellulose terpineol binder were thoroughly mixed at a mass ratio of 1:1.5 and ground in an agate mortar for 2 hours to prepare a uniform cathode slurry; PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.5 O 5+δ (PBSCF) Anode Material and Ce 0.1 Sm 0.9 O 2-δ (SDC) was mixed at a mass ratio of 6:4 and ground thoroughly for 1 hour. Then, the uniformly mixed powder and 7.5 wt.% ethyl cellulose terpineol binder were ground thoroughly at a mass ratio of 1:1 for 2 hours to prepare a uniform composite anode paste. The cathode paste containing JH-LSF was then uniformly coated onto a dense La substrate with a thickness of approximately 250 μm using screen printing technology. 0.8 Sr 0.2 Ga 0.8 Mg 0.2 One side of the O3 (LSGM) electrolyte was coated with a composite anode paste containing PBSCF and SDC, and the other side was coated with the same. Both electrodes were dried and annealed at 1000 °C for 2 h. Conductive silver paste was then applied to the surface of both electrodes for current collection. The battery was then encapsulated with silver paste and sealant to complete the fabrication of a single cell. The cathode side of the single cell was first purged with nitrogen at 800 °C to remove air, followed by activation with CO2 for 2 h, and then subjected to SOEC electrolysis testing.

[0026] Comparative Example 1 LSF powder preparation by conventional sol-gel method According to the chemical formula La 0.5 Sr 0.5 FeO 3-δ Sr(CH3COO)2, Fe(NO3)2·9H2O, and La(NO3)3·6H2O were weighed out according to stoichiometric ratio and dissolved sequentially in 100 mL of deionized water. The solution was continuously stirred magnetically at room temperature to form a homogeneous and clear mixed salt solution. Citric acid and ethylenediaminetetraacetic acid (EDTA) were added as complexing agents, and the molar ratio of total metal ions to citric acid to EDTA was controlled at 1:1:1.5. Subsequently, ammonia was added dropwise to adjust the pH of the solution to 7-8, resulting in a clear, transparent, and stable precursor solution. The precursor solution was transferred to an evaporating dish and placed in a constant temperature water bath at 80 °C for 10 h to obtain a gel-like substance.

[0027] The obtained gel-like material was calcined in an electronic universal furnace at a temperature of 200-300 °C to obtain a black, fluffy intermediate product, which was then thoroughly ground to obtain a black powder. The black powder was then placed in a muffle furnace and annealed at a heating rate of 3 °C / min to 600 °C for 2 h in a static air atmosphere to remove residual carbon and organic matter, thus obtaining the precursor powder.

[0028] The precursor powder was calcined in a conventional muffle furnace at 1000℃ for 5 h to obtain LSF powder prepared by the conventional sol-gel method.

[0029] See appendix Figure 1 This is a flowchart of the preparation of perovskite oxide JH-LSF powder by the flash Joule heating ultrafast synthesis process in this embodiment; See appendix Figure 2 The image shows the X-ray diffraction pattern of the JH-LSF powder in this embodiment. The results show that both JH-LSF and LSF powders have a tetragonal perovskite structure and a space group of [space group number missing]. P4 / mmm The diffraction peaks of JH-LSF shifted to lower angles, indicating that the cell structure expanded. Compared with the LSF powder prepared by the conventional sol-gel method in Comparative Example 1, this effectively introduced a high concentration of oxygen vacancies.

[0030] See appendix Figure 3a and Figure 3b SEM images of JH-LSF powder and LSF powder in this embodiment are shown below. Figure 3c The image shows the elemental scanning distribution of JH-LSF powder. It can be observed that the JH-LSF powder has finer and more uniformly distributed grains, and is porous. This indicates that high-temperature rapid synthesis can not only effectively inhibit grain agglomeration and coarsening, generating high-surface-area nanostructures, but also promote the formation of high-concentration oxygen vacancies and the construction of ideal defect structures.

[0031] See Figure 4, which shows the XPS spectra of JH-LSF and LSF. Compared to LSF synthesized by the traditional sol-gel method, JH-LSF synthesized by flash Joule heating exhibits stronger Fe 2p spectra. 2+ Characteristic peaks indicate the presence of Fe in the material. 2+ The increased concentration, according to the principle of electroneutrality, indicates that JH-LSF has a higher concentration of oxygen vacancies. Simultaneously, the significantly stronger proportion of adsorbed oxygen and reactive oxygen species in the O 1s spectrum also indicates a richer concentration of oxygen vacancies on the material surface. Therefore, the oxygen-vacancy-rich JH-LSF is beneficial for CO2 adsorption and dissociation, enhancing the catalytic activity of the CO2RR process.

[0032] See appendix Figure 5a The FTIR spectra of JH-LSF and LSF at 2350 cm⁻¹ -1and 1350 cm -1 CO2 and CO3 peaks appeared respectively. 2- The characteristic absorption peaks of JH-LSF show that the intensity of the absorption peak is significantly stronger than that of LSF, indicating that JH-LSF has a stronger adsorption capacity for CO2. (The remaining text appears to be incomplete and requires further context.) Figure 5b From the Raman spectra of JH-LSF and LSF, it can be seen that JH-LSF is at 1060 cm⁻¹. -1 More pronounced CO3 was detected nearby. 2- The characteristic absorption peaks indicate that CO2 molecules are more readily chemically adsorbed and converted into carbonate intermediates on the JH-LSF surface. JH-LSF, as a cathode material for SOEC, is more conducive to promoting the CO2 reduction reaction, thereby improving the electrochemical performance of CO2 electrolysis.

[0033] Referring to Figure 6, which shows the EIS curves of symmetrical cells of JH-LSF and LSF in a CO2:CO = 1:1 atmosphere at 600-800 °C, JH-LSF exhibits lower impedance than LSF at all temperatures, and its polarization resistance is 0.06 Ω cm at 800 °C. 2 With an activation energy of 0.78 eV, lower than LSF's 0.90 eV, the JH-LSF material exhibits higher electrocatalytic activity in SOEC. See Figure 7 for the current-voltage diagram of the electrolytic cell in operation. Figure 7a JH-LSF material, prepared by flash Joule heating, was used as the SOEC cathode. During CO2 electrolysis, the electrolysis current density at 1.5 V and 800 °C reached 2.88 A / cm². -2 ; Figure 7b When LSF material prepared by the conventional sol-gel method is used as the SOEC cathode, the electrolysis current density at 1.5V and 800 °C is only 0.94 A cm⁻¹. -2 The electrolysis current density of JH-LSF is 3.06 times that of LSF. Therefore, the superior carbon dioxide electrolysis performance of the JH-LSF cathode material is due to the abundant oxygen vacancies within the material, which significantly reduces the migration energy barrier of oxygen ions in the crystal lattice and promotes rapid oxygen ion conduction. At the same time, the high concentration of oxygen vacancies can also effectively weaken the C=O bonds in the CO2 molecule, greatly enhancing the chemical adsorption and activation of CO2 on the cathode surface, thereby significantly enhancing the overall electrolysis performance of the battery and accelerating the CO2 reaction kinetics.

[0034] Figure 8a Figures 1 and 2 show the EIS curves of the full cells of JH-LSF and LSF as SOEC cathodes at different temperatures, respectively. The polarization resistance of JH-LSF is lower at all temperatures, reaching only 0.07 Ω cm at 800 °C. 2This further verifies that increasing the concentration of oxygen vacancies at the cathode is beneficial for improving the ion transport rate, thereby significantly improving the electrochemical performance of the battery. For example... Figure 9a The electrolytic stability of JH-LSF at 800 ℃ and 1.3 V is [not specified]. Figure 9b This is a SEM image after the stability test. It can be seen that the JH-LSF battery can stably electrolyze for more than 120 h at 800 ℃ and 1.3 V. After the stability test, the electrode and electrolyte interface are tightly bonded, and no obvious delamination or cracking was observed. It maintains good physical and chemical compatibility, which is conducive to the stable electrochemical performance of SOEC for long-term operation.

[0035] Example 2: According to the chemical formula Nd 0.6 Sr 0.4 FeO 3-δ Nd(NO3)3·6H2O, Sr(CH3COO)2, and Fe(NO3)2·9H2O were weighed out according to stoichiometric ratio and dissolved sequentially in 100 mL of deionized water. The solution was continuously stirred magnetically at room temperature to form a homogeneous and clear mixed salt solution. Citric acid and ethylenediaminetetraacetic acid (EDTA) were added as complexing agents, and the molar ratio of total metal ions to citric acid to EDTA was controlled at 1:1:1.5. Subsequently, ammonia was added dropwise to adjust the pH of the solution to 7-8, resulting in a clear, transparent, and stable precursor solution. The precursor solution was transferred to an evaporating dish and placed in a constant temperature water bath at 80 °C for 10 h to obtain a gel-like substance.

[0036] The obtained gel-like material was calcined in an electronic universal furnace at a temperature of 200-300 °C to obtain a black, fluffy intermediate product, which was then thoroughly ground to obtain a black powder. The black powder was then placed in a muffle furnace and annealed at a heating rate of 3 °C / min to 600 °C for 2 h in a static air atmosphere to remove residual carbon and organic matter, thus obtaining the precursor powder.

[0037] 12% by mass of conductive additive carbon black was added to the precursor powder and mixed thoroughly to improve the overall conductivity of the material under energized conditions, thus obtaining a composite precursor powder.

[0038] The composite precursor powder was uniformly distributed in a molybdenum boat (100×20×0.2mm) within a flash Joule heating apparatus. The chamber was evacuated and then argon gas was introduced. This process was repeated three times. No additional gas was introduced during the entire heating process, and it was completed in a static argon atmosphere without any gas flow. The temperature was monitored in real time by detecting the infrared radiation energy emitted from the object's surface. The calcination temperature was adjusted by controlling the applied current. The set temperature was 1050 ℃, the current was 350 A, the holding time was 35 s, and the heating rate was 100-150 K s.-1 After rapid heat treatment at 1050-1100 ℃, it was annealed at low temperature in a muffle furnace and treated at 550 ℃ for 30 min to obtain JH-NSF powder.

[0039] The cathode material NSF and 7.5 wt.% ethyl cellulose terpineol binder prepared above were thoroughly mixed at a mass ratio of 1:1.5 and ground in an agate mortar for 2 hours to prepare a uniform cathode slurry; PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.5 O 5+δ (PBSCF) Anode Material and Ce 0.1 Sm 0.9 O 2-δ (SDC) was mixed at a mass ratio of 6:4 and ground thoroughly for 1 hour. Then, the uniformly mixed powder and 7.5 wt.% ethyl cellulose terpineol binder were ground thoroughly at a mass ratio of 1:1 for 2 hours to prepare a uniform composite anode paste. The NSF-containing cathode paste was then uniformly coated onto a dense La film with a thickness of approximately 250 μm using screen printing technology. 0.8 Sr 0.2 Ga 0.8 Mg 0.2 One side of the O3 (LSGM) electrolyte was coated with a composite anode paste containing PBSCF and SDC, and the other side was coated with the same. Both electrodes were dried and annealed at 1000 °C for 2 h. Conductive silver paste was then applied to the surface of both electrodes for current collection. The battery was then encapsulated with silver paste and sealant to complete the fabrication of a single cell. The cathode side of the single cell was first purged with nitrogen at 800 °C to remove air, followed by activation with CO2 for 2 h, and then subjected to SOEC electrolysis testing.

[0040] Example 3: According to the chemical formula Pr 0.5 Ba 0.5 FeO 3-δ Ba(CH3COO)2, Fe(NO3)2·9H2O, and Pr(NO3)3·6H2O were weighed out according to stoichiometric ratio and dissolved sequentially in 100 mL of deionized water. The solution was continuously stirred magnetically at room temperature to form a homogeneous and clear mixed salt solution. Citric acid and ethylenediaminetetraacetic acid (EDTA) were added as complexing agents, and the molar ratio of total metal ions to citric acid to EDTA was controlled at 1:1:1.5. Subsequently, ammonia was added dropwise to adjust the pH of the solution to 7-8, resulting in a clear, transparent, and stable precursor solution. The precursor solution was transferred to an evaporating dish and placed in a constant temperature water bath at 80 °C for 10 h to obtain a gel-like substance.

[0041] The obtained gel-like material was calcined in an electronic universal furnace at a temperature of 200-300 °C to obtain a black, fluffy intermediate product, which was then thoroughly ground to obtain a black powder. The black powder was then placed in a muffle furnace and annealed at a heating rate of 3 °C / min to 600 °C for 2 h in a static air atmosphere to remove residual carbon and organic matter, thus obtaining the precursor powder.

[0042] A conductive additive is added to the precursor powder and mixed thoroughly to improve the overall conductivity of the material under energized conditions, thus obtaining a composite precursor powder.

[0043] The composite precursor powder was uniformly distributed in a molybdenum boat (100×20×0.2mm) within a flash Joule heating apparatus. The chamber was evacuated and then argon gas was introduced. This process was repeated three times. No additional gas was introduced during the entire heating process, and it was completed in a static argon atmosphere without any gas flow. The temperature was monitored in real time by detecting the infrared radiation energy emitted from the object's surface. The calcination temperature was adjusted by controlling the applied current. The set temperature was 1000 ℃, the current was 250 A, the holding time was 40 s, and the heating rate was 100-150 K s. -1 After rapid heat treatment at 1000-1100 ℃, it is annealed at low temperature in a muffle furnace and treated at 600 ℃ for 30 min to obtain JH-PBF powder.

[0044] The cathode material PBF prepared above and 7.5 wt.% ethyl cellulose terpineol binder were thoroughly mixed at a mass ratio of 1:1.5 and ground in an agate mortar for 2 hours to prepare a uniform cathode slurry; PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.5 O 5+δ (PBSCF) Anode Material and Ce 0.1 Sm 0.9 O 2-δ (SDC) was mixed at a mass ratio of 6:4 and ground thoroughly for 1 hour. Then, the uniformly mixed powder and 7.5 wt.% ethyl cellulose terpineol binder were ground thoroughly at a mass ratio of 1:1 for 2 hours to prepare a uniform composite anode paste. The PBF-containing cathode paste was then uniformly coated onto a dense La substrate with a thickness of approximately 250 μm using screen printing technology. 0.8 Sr 0.2 Ga 0.8 Mg 0.2One side of the O3 (LSGM) electrolyte was coated with a composite anode paste containing PBSCF and SDC, and the other side was coated with the same. Both electrodes were dried and annealed at 1000 °C for 2 h. Conductive silver paste was then applied to the surface of both electrodes for current collection. The battery was then encapsulated with silver paste and sealant to complete the fabrication of a single cell. The cathode side of the single cell was first purged with nitrogen at 800 °C to remove air, followed by activation with CO2 for 2 h, and then subjected to SOEC electrolysis testing.

[0045] For any points not covered above, existing technologies shall apply.

[0046] Although specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them, without departing from the direction of the invention or exceeding the scope defined by the appended claims. Those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc., made to the above embodiments based on the technical essence of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing an oxygen-rich defect iron-based perovskite oxide material, characterized in that, The general chemical formula of the iron-based perovskite oxide material is ABO. 3-δ Where A is one or more of La, Pr, Nd, Sm, Gd, Sr, Ca, and Ba, and B is Fe, with 3 > δ > 0; the preparation includes the following steps: S1: Provide a metal source at site A and an iron source at site B according to the stoichiometric ratio. Add the metal source to a deionized aqueous solution in sequence, mix and stir, add the complex, adjust the pH of the solution to 7-8 and perform hydrothermal treatment to obtain the precursor gel. S2: The precursor gel is precalcined to obtain a fluffy black intermediate, which is ball-milled to obtain a black powder. The black powder is then annealed to remove residual carbon and organic matter, thus obtaining the precursor powder. S3: Add a conductive additive to the precursor powder and mix thoroughly to obtain a composite precursor powder; S4: The composite precursor powder is placed in a molybdenum boat or tungsten boat and subjected to flash Joule heat treatment under an inert atmosphere, a low oxygen partial pressure atmosphere or a vacuum atmosphere, followed by low-temperature annealing to obtain an oxygen-rich defect iron-based perovskite oxide material.

2. The preparation method according to claim 1, characterized in that, The specific parameters for flash Joule heat treatment are: a set temperature of 900-1200 ℃ and a heating rate of 100-150 K s. -1 The current is 200-500 A, and the heat preservation time is 10-50 s.

3. The preparation method according to claim 1, characterized in that, The general chemical formula of the iron-based perovskite oxide is A. x A' (1-x) FeO 3-δ Where A = one of La, Pr, Nd, Sm, and Gd, A' = one of Sr, Ca, and Ba, and x = 0.2~0.

8.

4. The preparation method according to claim 1, characterized in that, In step S2, the black intermediate is pre-calcined at 200-300 °C for 2-5 h, and then annealed at 600 °C for 2 h.

5. The preparation method according to claim 1, characterized in that, The metal source and iron source are nitrates, acetates, chlorides, or any combination thereof; the complexing agent is citric acid and ethylenediaminetetraacetic acid.

6. The preparation method according to claim 1, characterized in that, The conductive additive is selected from carbon black, graphite, graphene, carbon nanotubes or any combination thereof, and its addition amount is 10%-15% of the precursor powder mass.

7. The preparation method according to claim 1, characterized in that, The inert atmosphere is argon or nitrogen; the low oxygen partial pressure atmosphere is a protective atmosphere with an oxygen volume fraction not exceeding 1%.

8. The preparation method according to claim 1, characterized in that, In step S3, the low-temperature annealing treatment is carried out at a temperature of 500-600 ℃ for 25-35 min.

9. An oxygen-rich defect iron-based perovskite oxide material, characterized in that, The material is prepared by the preparation method according to any one of claims 1-8.

10. The application of the oxygen-rich defect iron-based perovskite oxide material as described in claim 9 in a solid oxide electrolytic cell, characterized in that: Used as the cathode of a solid oxide electrolytic cell for CO2 electrolysis, H2O electrolysis, or CO2-H2O co-electrolysis.

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