A perovskite SrFeO3 material, its preparation method and application

Abstract

The application discloses a perovskite SrFeO3 material and a preparation method and application thereof. In the application, the symmetrical electrode material is an ABO3 type perovskite, and the chemical formula is Sr 0.9 Fe 0.8 Y 0.1 Co 0.1 O 3‑δ , which is prepared by a combustion method. The ABO3 type perovskite material in the application can simultaneously transport electrons, oxygen ions and protons, can effectively reduce the polarization resistance of a symmetrical proton-conducting solid oxide battery, improves the battery power density and the water electrolysis hydrogen production performance, and the symmetrical electrode material can maintain good structural stability in air and hydrogen atmosphere, and can effectively enhance the operation stability of the battery.

Description

Technical Field

[0001] This invention relates to the fields of solid oxide fuel cells and ceramic materials, specifically to a perovskite SrFeO3 material, its preparation method, and its applications. Background Technology

[0002] Compared to traditional fuel cells, symmetric solid oxide fuel cells (SSOFCs) with identical electrode / electrolyte interfaces offer several advantages: 1. Significantly simplified fabrication process: SSOFCs utilize identical cathode and anode materials, resulting in a highly symmetrical structure, simplifying the cell structure and significantly shortening the SOFC fabrication cycle. 2. Improved chemical compatibility and thermal matching among cell components: Since the SSOFC cathode and anode are identical, the interfaces between the two electrodes and the electrolyte are completely consistent. Therefore, compared to traditional SOFCs, SSOFCs only require consideration of the compatibility of one electrode material with the remaining components, making it easier to meet the compatibility and thermal matching requirements of SOFC components. 3. Significantly reduced fabrication costs: The identical cathode and anode in SSOFCs simplify the sintering process compared to traditional asymmetric SOFCs. Because SOFC electrodes have high heat treatment temperatures, reducing the sintering process effectively lowers energy consumption and fabrication costs, facilitating large-scale SOFC production. Currently, the main challenge for SSOCs is finding electrode materials with sufficiently superior electrochemical performance and redox reversibility to completely replace traditional asymmetric SOFCs in terms of performance.

[0003] ABO3 structure oxides are the most common and prevalent structural type in symmetrical electrode materials. They are divided into A-sites and B-sites. The coordination number of the A-site ion is 12, surrounded by 12 oxygen ions. Some oxygen ion sites in the crystal structure are more easily activated and perturbed by heat, resulting in the formation of a certain concentration of oxygen vacancies. When a low-valence metal ion partially replaces the A-site ion, the effect of these oxygen vacancies formed by high-temperature perturbation increases significantly, and they are prone to valence changes under high-temperature conditions, resulting in higher electronic conductivity. Therefore, using perovskite structure materials as cathodes is beneficial for oxygen reduction catalysis and can improve ionic conductivity.

[0004] Compared to traditional oxygen-ion-conducting solid oxide fuel cells (O-SOFCs), proton-conducting solid oxide fuel cells (P-SOFCs) have numerous advantages, such as a lower operating temperature range (500-700℃) and direct H2O generation at the cathode side, avoiding fuel dilution. The proton conductor exhibits high ionic conductivity and low electronic conductivity in the medium-low temperature range (350-600℃). Moreover, proton conduction between two adjacent oxygen atoms has a low migration activation energy (0.4-0.6eV), which makes proton generation and oxygen reduction reactions easier. The lower operating temperature means lower requirements for the selection of other components and sealing conditions in SOFCs, thereby further enhancing the mechanical strength of the battery, extending its service life, and promoting the overall development of SOFC operating temperatures towards medium and low temperatures. Summary of the Invention

[0005] One of the objectives of this invention is to provide a perovskite SrFeO3 material.

[0006] The second objective of this invention is to provide a method for preparing the above-mentioned perovskite SrFeO3 material.

[0007] The third objective of this invention is to provide the application of the above-mentioned perovskite SrFeO3 material in proton-type symmetric solid oxide batteries. The perovskite SrFeO3 material, when combined with electrolyte BZCYYb, can be used as a symmetric electrode material for proton-type symmetric solid oxide batteries.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first aspect of this invention provides a perovskite SrFeO3 material, wherein the chemical formula of the material is Sr 0.9 Fe 0.8 Y 0.1 Co 0.1 O 3-δ , where δ is the oxygen vacancy content, δ=0~0.1.

[0009] A second aspect of the present invention provides a method for preparing the above-mentioned perovskite SrFeO3 material, comprising the following steps: S1, according to the chemical formula Sr 0.9 Fe 0.8 Y 0.1 Co 0.1 O 3-δ The stoichiometric ratios of Sr, Fe, Y, and Co elements in the strontium source, iron source, yttrium source, and cobalt source are accurately weighed. S2. Weigh out the yttrium source, strontium source, iron source and cobalt source and add them to the nitric acid solution in sequence. Heat and stir until dissolved to obtain solution A. Then add citric acid and EDTA in sequence, then add nitric acid and heat and stir until dissolved to obtain solution B. S3. Adjust the pH of solution B to weakly alkaline to obtain solution C; S4. Heat solution C until it evaporates to a gel-like state and then spontaneously combusts to generate powder, thus obtaining precursor powder D. S5. The precursor powder D is heated to 1000℃ in air atmosphere and sintered for 3-5 hours to obtain perovskite SrFeO3 material.

[0010] Preferably, in step S1, the strontium source is Sr(NO3)2, the iron source is Fe(NO3)3·9H2O, the yttrium source is Y2O3, and the cobalt source is Co(NO3)2·6H2O.

[0011] Preferably, the molar ratio of total metal ions:citric acid:EDTA in solution B is 1:1:0.8.

[0012] Preferably, in step S3, the pH of solution B is adjusted to 7-8 using ammonia.

[0013] Preferably, in step S5, the precursor powder D is heated to 1000°C at a heating rate of 5°C / min for pre-calcination, and then cooled to 600°C at a cooling rate of 5°C / min before being cooled in the furnace.

[0014] A third aspect of the present invention provides the above-mentioned perovskite SrFeO3 material and electrolyte BaZr. 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ Application of (BZCYYb) composite as a symmetric electrode material for proton-type symmetric solid oxide batteries in the preparation of symmetric solid oxide fuel cells.

[0015] Furthermore, using BZCYYb material as the proton electrolyte, a slurry obtained by combining perovskite SrFeO3 material with electrolyte BZCYYb as the symmetric electrode material of a proton-type symmetric solid oxide fuel cell, and mixing binder and organic solvent is coated on both sides of the BZCYYb electrolyte sheet to prepare a symmetric cell.

[0016] Furthermore, during operation, fuel gas, which is hydrogen, is introduced into the anode.

[0017] The perovskite material and electrolyte BZCYYb composite of the present invention are used as the symmetric electrode material of a proton-conducting symmetric solid oxide fuel cell. The working principle of the prepared proton-conducting symmetric solid oxide fuel cell is as follows: For H-SOFC, when H2 is used as fuel gas, the following reaction occurs: First, H2 is introduced to the anode side and is catalytically dissociated into protons (H2O2). +Simultaneously, electrons are released, and the protons generated at the anode are transported to the cathode side through the dense electrolyte. At the cathode, oxygen captured from the air undergoes adsorption and dissociation processes under the action of a catalytic material, reacting with electrons from the external circuit to generate O2. 2- Finally O 2- With H + The reaction produces H2O, and at the same time, electrons are transmitted through the external circuit to form an electric current, thus realizing the conversion of chemical energy into electrical energy.

[0018] H-SOFC has many unique advantages: 1) The proton radius is smaller than that of oxygen ions, making it easier to conduct in oxides, and the activation energy of proton conduction is lower than that of oxygen ion conduction; 2) Proton conductor-based materials can exhibit higher conductivity at lower temperatures, which can effectively avoid the increase in ohmic resistance caused by the decrease in conductivity due to temperature when applied to batteries; 3) The product H2O in H-SOFC is generated on the cathode side, which effectively avoids the dilution of the anode fuel gas by H2O and improves fuel utilization to a certain extent.

[0019] Compared with the prior art, the present invention has the following beneficial effects: 1. The perovskite SrFeO3 prepared in this invention, when combined with electrolyte BZCYYb, serves as a symmetric electrode material for proton-type symmetric solid oxide batteries. This material is a single solid solution and possesses excellent triple conduction capabilities of oxygen ions, electrons, and protons, meeting the oxygen ion, electron, and proton exchange requirements of symmetric electrode materials. The impedance of this symmetric electrode material decreases with increasing temperature, thus better meeting the application requirements of symmetric proton-type solid oxide batteries.

[0020] 2. The perovskite synthesized in this invention, when combined with electrolyte BZCYYb, serves as a symmetric electrode material for proton-type symmetric solid oxide batteries. It maintains a stable phase structure under a strongly reducing atmosphere with a wet cathode, indicating that the electrode material possesses good structural stability and can simultaneously conduct electrons, ions, and protons. This triple-conducting symmetric electrode material reduces interfacial resistance, achieving higher power output and lower polarization impedance.

[0021] 3. In this invention, Sr 0.9 Fe 0.8 Y 0.1 Co 0.1 O 3-δ The composite of perovskite and BZCYYb, when used as an electrode material for proton-type symmetric solar cells, achieves a maximum output power of 110.7 mW / cm² at an operating temperature of 700℃. 2 The ohmic impedance is 1.38 Ωcm. 2 The polarization impedance is 0.5 Ωcm. 2When used as an electrolytic cell for hydrogen production by electrolyzing water, the corresponding electrolytic current density at 700℃ and 2V is 0.782A / cm². 2 . Attached Figure Description

[0022] Figure 1 XRD pattern of SFYC perovskite material prepared by combustion method after being combined with BZCYYb; Figure 2 Impedance diagram of a full cell of a proton-type symmetric solid oxide battery supported by a proton-type symmetric battery using SFYC perovskite material prepared by combustion method and combined with BZCYYb as electrolyte under humid hydrogen gas. Figure 3 IVP curves of a full cell of a proton-type symmetric solid oxide battery supported by a combustion-prepared SFYC perovskite material and BZCYYb composite as an electrolyte under humid hydrogen gas. Figure 4 Voltage and current density curves of SFYC perovskite material prepared by combustion method combined with BZCYYb as electrolyte support for water electrolysis to produce hydrogen in a proton-type symmetric solid oxide battery. Detailed Implementation

[0023] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0024] Example 1 Preparation of Sr by combustion method 0.9 Fe 0.8 Y 0.1 Co 0.1 O 3-δThe specific preparation process of perovskite materials is as follows: Weigh 5.714g of strontium nitrate (Sr(NO3)2), 0.3387g of yttrium oxide (Y2O3), 0.8731g of cobalt nitrate (Co(NO3)2·6H2O), and 9.696g of ferric nitrate (Fe(NO3)3·9H2O). First, dissolve the yttrium oxide in 15mL of nitric acid, then add 150mL of deionized water to this solution to obtain a primary solution. Next, add the strontium nitrate, cobalt nitrate, and ferric nitrate to the primary solution in that order, ensuring that each new reagent is completely dissolved. After the above reagents are dissolved, add 12.6086g of citric acid. After the acid is completely dissolved, add 14.0275g of EDTA, and finally add 5mL of nitric acid to the solution. During this process, the beaker must be placed on a magnetic stirrer and heated to 60℃. After the EDTA dissolves, add ammonia to adjust the pH to 7-8. Pour this solution into an evaporating dish and heat until it becomes sticky and small bubbles continuously emerge. Stir with a glass rod until it spontaneously combusts to obtain the precursor powder. Place the precursor powder in a crucible and put it in a muffle furnace. In an air atmosphere, raise the temperature to 1000℃ at a heating rate of 5℃ / min and calcine for 3 hours. Then, cool the temperature to 600℃ at a cooling rate of 5℃ / min and cool with the furnace to obtain Sr. 0.9 Fe 0.8 Y 0.1 Co 0.1 O 3-δ Perovskite materials, namely SFYC perovskite materials.

[0025] X-ray diffraction was used to determine the phase structure of the composite material of SFYC perovskite and BZCYYb, such as... Figure 1 As shown, it is the prepared Sr 0.9 Fe 0.8 Y 0.1 Co 0.1 O 3-δ XRD patterns of perovskite materials combined with BZCYYb were obtained, and their chemical compatibility was investigated after treatment at 1000℃ for 3 hours. Figure 1 It can be seen that Sr 0.9 Fe 0.8 Y 0.1 Co 0.1 O 3-δ The material, after being combined with BZCYYb, is only Sr 0.9 Fe 0.8 Y 0.1 Co 0.1 O 3-δ The superposition of the BZCYYb diffraction peaks with the presence of no second phase or splitting peaks confirms that the perovskite Sr prepared in this invention is indeed of high quality. 0.9 Fe 0.8 Y 0.1 Co0.1 O 3-δ No phase reaction occurred after the material was combined with BZCYYb, proving that the two have good chemical compatibility.

[0026] Example 2 Electrolyte-supported symmetric solar cells were fabricated using SFYC perovskite material. The specific fabrication process is as follows: SFYC perovskite material prepared by combustion was mixed with BaZr... 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ After being composited with (BZCYYb), it is used as the electrode of a symmetrical battery. Using BZCYYb as the electrolyte material, 0.05g of perovskite powder and 0.05g of BZCYYb are weighed and placed in a mortar. An appropriate amount of alcohol is added and the mixture is ground until the alcohol evaporates. Then, 0.2g of 10% ethyl cellulose terpineol solvent (the mass ratio of ethyl cellulose to terpineol is 1:10) is added and the mixture is ground for another 2 hours to obtain a composite cathode slurry. The prepared cathode slurry is coated on both sides of the BZCYYb electrolyte sheet, with three coats on each side. After the first coat is applied, the sheet is placed in an 80℃ oven to dry before the second coat is applied. After the second coat is applied, the sheet is placed in an 80℃ oven to dry again before the third coat is applied. After all the sheets are completely dried, they are placed in a muffle furnace at 1000℃ and calcined for 3 hours. Dilute silver paste is brushed onto the two electrodes after calcination. The coiled silver wire is placed on the two electrodes after the dilute silver paste has been applied, and it is tightly bonded to them with conductive adhesive. After the conductive adhesive dries, an electrolyte-supported proton-type symmetric cell is obtained.

[0027] Hydrogen gas at a flow rate of 30 mL / min was introduced into the anode side of the electrolyte-supported proton-type symmetric cell prepared in Example 2. Static air was used as the oxidant. The impedance at 750 °C, 700 °C, 650 °C, 600 °C, and 550 °C, and the maximum power density at 700 °C, 650 °C, 600 °C, and 550 °C were recorded. The results are as follows: Figure 2 , Figure 3 As shown. By Figure 2 It can be seen that the proton electrolyte-supported symmetric cell with SFYC-BZCYYb composite material as electrode achieves ohmic impedances of 1.38, 1.66, 2.12, and 3.020 Ωcm at 700℃, 650℃, 600℃, and 550℃, respectively. 2 The polarization impedances can reach 0.5, 1.13, 2.54, and 5.91 Ωcm, respectively. 2 ,Depend on Figure 3 It can be seen that the maximum power density at 700℃, 650℃, 600℃, and 550℃ can reach 110.7, 78.94, 50, and 27.42 mW / cm³, respectively. 2 .

[0028] Example 3 Hydrogen gas containing water was introduced into the fuel gas side of the electrolyte-supported proton-type symmetric battery prepared in Example 2, making it an electrolytic cell. Static air was used as the oxidant, and the maximum current density at 700°C and 650°C was recorded. The results are as follows: Figure 4 As shown.

[0029] Depend on Figure 4 It can be seen that the electrolyte-supported proton-type symmetric cell with SFYC-BZCYYb composite material as electrode can achieve a maximum current density of 0.782 and 0.427 A cm⁻¹ at 700℃ and 650℃ under a constant voltage of 2.0V, respectively. -2 .

[0030] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A perovskite SrFeO3 material, characterized in that, The chemical formula of the material is Sr 0.9 Fe 0.8 Y 0.1 Co 0.1 O 3-δ , where δ is the oxygen vacancy content, δ=0~0.

1.

2. A method for preparing the perovskite SrFeO3 material according to claim 1, characterized in that, Includes the following steps: S1, according to the chemical formula Sr 0.9 Fe 0.8 Y 0.1 Co 0.1 O 3-δ The stoichiometric ratios of Sr, Fe, Y, and Co elements in the strontium source, iron source, yttrium source, and cobalt source are accurately weighed. S2. Weigh out the yttrium source, strontium source, iron source and cobalt source and add them to the nitric acid solution in sequence. Heat and stir until dissolved to obtain solution A. Then add citric acid and EDTA in sequence, then add nitric acid and heat and stir until dissolved to obtain solution B. S3. Adjust the pH of solution B to weakly alkaline to obtain solution C; S4. Heat solution C until it evaporates to a gel-like state and then spontaneously combusts to generate powder, thus obtaining precursor powder D. S5. The precursor powder D is heated to 1000℃ in air atmosphere and sintered for 3-5 hours to obtain perovskite SrFeO3 material.

3. The method for preparing a perovskite SrFeO3 material according to claim 2, characterized in that, In step S1, the strontium source is Sr(NO3)2, the iron source is Fe(NO3)3·9H2O, the yttrium source is Y2O3, and the cobalt source is Co(NO3)2·6H2O.

4. The method for preparing a perovskite SrFeO3 material according to claim 2, characterized in that, In step S2, the molar ratio of total metal ions: citric acid: EDTA in solution B is 1:1:0.

8.

5. The method for preparing a perovskite SrFeO3 material according to claim 2, characterized in that, In step S3, ammonia is added to adjust the pH of solution B to 7-8.

6. The method for preparing a perovskite SrFeO3 material according to claim 2, characterized in that, In step S5, the precursor powder D is heated to 1000°C at a heating rate of 5°C / min for pre-calcination, and then cooled to 600°C at a cooling rate of 5°C / min before being cooled in the furnace.

7. The method for preparing a perovskite SrFeO3 material according to claim 2, characterized in that, In step S3, the calcination temperature is 1000℃ and the calcination time is 3h.

8. The application of the perovskite SrFeO3 material according to claim 1 in the preparation of proton-type symmetric solid oxide fuel cells, characterized in that, The perovskite SrFeO3 material and the electrolyte BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ The materials are composited at a mass ratio of 1:1 and used as symmetric electrode materials for proton-type symmetric solid oxide fuel cells.

9. The application according to claim 8, characterized in that, In the aforementioned proton-type symmetric solid oxide fuel cell, the electrolyte used is BaZr. 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ Material.

10. The application according to claim 8, characterized in that, During operation, fuel gas, which is hydrogen, is introduced into the anode.

Images