Air Electrode, Its Preparation Method and Application

Abstract

This invention relates to the field of reversible solid oxide battery technology, providing an air electrode, its preparation method, and its application. This invention prepares Ba through a sol-gel method and stepwise calcination. 0.9 Ce 0.1 Fe 1‑x Y x O 3‑δ (x=0.05, 0.1) materials, then using the precursor solution PrCoO 3‑δ Impregnation is performed to prepare an air electrode composite layer. Using the above-mentioned materials to aggregate the air electrode can improve the oxygen reduction and oxygen evolution reaction (ORR / OER), resulting in excellent battery performance in the mid-temperature range and reduced costs.

Description

Technical Field

[0001] This invention relates to the field of reversible solid oxide battery technology, specifically to an air electrode, its preparation method, and its application. Background Technology

[0002] Reversible solid oxide cells (R-SOCs) are a type of highly efficient energy conversion device capable of flexibly switching between fuel cell (SOFC) and electrolyzer (SOEC) modes. They enable bidirectional conversion of electrical and chemical energy, showing broad application prospects in renewable energy storage, green hydrogen production, and CO2 resource utilization. R-SOCs typically consist of key components such as an electrolyte, fuel electrode, air electrode, and connectors. The air electrode plays a dual-function catalytic role in the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), and its electrochemical activity, thermal matching, and long-term stability have a decisive impact on the overall performance of the battery.

[0003] Currently, medium- and high-temperature R-SOC air electrodes mainly use cobalt-containing perovskite oxides, such as La 1-x Sr x Co 1-y Fe y O 3-δ (LSCF) and Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-δ (BSCF), etc. Due to the strong electron mobility and variable valence state of Co, these materials typically exhibit excellent mixed-ion electronic conductivity (MIEC) and fast surface oxygen exchange kinetics, resulting in low polarization resistance and high catalytic activity at high temperatures. However, cobalt-based perovskite air electrodes still face significant limitations in practical applications: First, cobalt-based materials generally have a high coefficient of thermal expansion (15~20×10⁻⁶). - 6 K -1 Significant thermal expansion mismatch exists between cobalt and commonly used electrolyte materials (such as YSZ or GDC), which easily generates interfacial thermal stress during long-term thermal cycling, leading to electrode cracking, interfacial delamination, and performance degradation. Secondly, cobalt resources are limited in reserves and expensive, significantly increasing the material cost of R-SOC systems and hindering large-scale applications.

[0004] To reduce costs and improve thermomechanical stability, recent research has increasingly shifted towards cobalt-free or low-cobalt air electrode systems. Among these, iron-based perovskite oxides have attracted widespread attention due to their abundant resources, good chemical stability, and relatively low coefficient of thermal expansion. For example, La... 1-x Srx FeO 3-δ (LSF) and BaFeO 3-δ Materials such as basalt oxide (BFO) are considered potential candidate systems for cobalt-free air electrodes. Previous studies have shown that BFO-based materials exhibit good oxygen ion transport and electrocatalytic activity at high temperatures, and the oxygen vacancy concentration and electronic structure can be further modulated through A / B site doping. However, existing cobalt-free iron-based perovskites still have significant shortcomings in the mid-temperature range (600–800 °C): on the one hand, the lack of Co leads to a decrease in electronic structure modulation ability, significantly reducing the surface oxygen exchange rate and bulk oxygen ion diffusion capacity under mid-temperature conditions, resulting in sluggish ORR / OER kinetics and increased electrode polarization resistance; on the other hand, BFO-type materials are prone to phase transformation and oxygen vacancy ordering during operation, leading to decreased long-term stability. Furthermore, although the coefficient of thermal expansion of iron-based materials is lower than that of traditional cobalt-based systems, there is still a certain degree of mismatch between them and the electrolyte, and existing strategies for reducing TEC through heterovalent doping often result in decreased oxygen vacancy concentration and weakened electrocatalytic activity.

[0005] Therefore, developing novel air electrode materials that combine high oxygen electrocatalytic activity, excellent thermomechanical stability, and low cost, especially achieving rapid oxygen reaction kinetics and thermal expansion matching under mesotemperature conditions of 600–800℃, remains a key technical problem to be solved in the R-SOC field. Summary of the Invention

[0006] Therefore, it is necessary to provide an air electrode, its preparation method, and its application, which can have excellent application performance in the mid-temperature range and reduce the cost of cobalt-containing perovskite materials.

[0007] The present invention adopts the following technical solution: This invention provides an air electrode, mainly prepared from material A and material B; wherein, material A is Ba. 1- x Ce x Fe 1-y Y y O 3-δ Furthermore, x takes values ​​in the range 0 < x ≤ 0.1, y takes values ​​in the range 0 < y ≤ 0.1, and δ takes values ​​in the range 0 < δ ≤ 0.5; material B is PrCoO 3-δ Material.

[0008] In some embodiments, material A is preferably Ba. 0.9 Ce 0.1 Fe 0.95 Y 0.05 O 3-δ .

[0009] In some embodiments, the preparation method of material A includes: preparing a precursor solution containing Ba, Ce, Fe, and Y sources, with a pH of 7-8; evaporating the precursor solution to prepare a gel-like substance; heating and burning the gel-like substance to form a black precursor, grinding it, and then subjecting it to a primary calcination in air to obtain a primary calcined powder; compressing the primary calcined powder into tablets, subjecting it to a secondary calcination in air, and grinding it to obtain Ba. 1-x Ce x Fe 1-y Y y O 3-δ Powder materials.

[0010] In some embodiments, the precursor solution further contains ethylenediaminetetraacetic acid, citric acid, and polyethylene glycol, with the molar ratio of the metal cation, ethylenediaminetetraacetic acid, and citric acid being 1:1:1.5.

[0011] In some embodiments, the primary calcination temperature is 600°C and the duration is 4 hours; the secondary calcination temperature is 1100°C and the duration is 5 hours.

[0012] In some embodiments, material B is prepared by drying and sintering a solution containing Pr and Co sources.

[0013] This invention provides a method for preparing an air electrode, comprising the following steps: Prepare an air electrode slurry containing material A; The air electrode slurry is coated on the surface of the electrolyte structure layer, dried and sintered for the first time to form electrode layer A. An impregnation solution containing Pr and Co sources was prepared and used to impregnate the surface of electrode layer A. The impregnation was then dried and sintered to obtain an air electrode composite layer containing material B.

[0014] In some embodiments, the concentration of the impregnation solution is 0.4M, and the amount of electrode layer A used per square centimeter is 5~20µL.

[0015] In some embodiments, the process parameters for the initial drying and sintering are: sintering at 1000°C for 2 hours; and the process parameters for the secondary drying and sintering are: sintering at 800°C for 2 hours.

[0016] The above-mentioned method for preparing air electrodes is applied in the preparation of reversible solid oxide batteries.

[0017] Compared with the prior art, the core technical advantages and beneficial effects of this invention are as follows: This invention prepares Ba using a sol-gel method and a stepwise calcination method. 0.9 Ce 0.1 Fe 1-x Y x O3-δ (x=0.05, 0.1) materials, then the precursor solution PrCoO 3-δ Impregnation forms a composite layer for the air electrode. The related materials aggregated in the air electrode can significantly improve the oxygen reduction and oxygen evolution reaction (ORR / OER), resulting in excellent battery performance over the mid-temperature range and reduced costs.

[0018] This invention presents a reversible solid oxide battery composite air electrode achieved through the synergistic effect of doping and impregnation strategies. This is achieved by using iron-based perovskite Ba... 0.9 Ce 0.1 FeO 3-δ The B site of (BCF) is doped with a metal cation, Y, to improve the local electronic environment of the material and stabilize the phase structure. Then, the precursor solution PrCoO is... 3-δ The material is impregnated on its surface. While maintaining high thermomechanical compatibility with the electrolyte, it can also significantly improve its ORR / OER catalytic activity, enabling R-SOC to operate efficiently at intermediate temperatures. Attached Figure Description

[0019] Figure 1 The images shown are XRD patterns of the materials prepared in the embodiments and comparative examples of this invention; wherein, BCF refers to Ba. 0.9 Ce 0.1 FeO 3-δ Material, BCFY0.025 refers to Ba 0.9 Ce 0.1 Fe 0.975 Y 0.025 O 3-δ Material, BCFY0.05 ​​refers to Ba 0.9 Ce 0.1 Fe 0.95 Y 0.05 O 3-δ Material, BCFY0.1 refers to Ba 0.9 Ce 0.1 Fe 0.9 Y 0.1 O 3-δ Material, PCO refers to PrCoO 3-δ Powder material, BCFY0.05-PCO refers to PrCoO 3-δ Impregnation Ba 0.9 Ce 0.1 Fe 0.95 Y 0.05 O 3-δ The composite material is formed by calcination.

[0020] Figure 2 For Ba 0.9 Ce 0.1 Fe 0.95 Y0.05 O 3-δ -PrCoO 3-δ SEM image of the composite material.

[0021] Figure 3 Chemical impedance spectra were obtained by testing the symmetrical battery sample formed using the material prepared in Example 1 and the symmetrical battery sample formed using the composite materials of Examples 1 and 2 at 800°C for application performance testing.

[0022] Figure 4 Ba was used for the second application performance test. 0.9 Ce 0.1 FeO 3-δ IP and IV performance curves of a single cell sample formed by the material (BCF) under different temperature conditions with hydrogen as fuel.

[0023] Figure 5 Ba was used for the second application performance test. 0.9 Ce 0.1 Fe 0.95 Y 0.05 O 3-δ The IP and IV performance curves of a single cell sample formed from the material (BCFY0.05) were obtained under different temperature conditions with hydrogen as fuel.

[0024] Figure 6 Ba was used for the second application performance test. 0.9 Ce 0.1 Fe 0.95 Y 0.05 O 3-δ With PrCoO 3-δ IP and IV performance curves of a single cell sample formed by the composite material (BCFY0.05-PCO) under different temperature conditions with hydrogen as fuel.

[0025] Figure 7 Ba was used for the second application performance test. 0.9 Ce 0.1 FeO 3-δ IV performance curves of single-cell test samples formed by the material (BCF) under different temperature conditions in a 5% H2O air atmosphere.

[0026] Figure 8 Ba was used for the second application performance test. 0.9 Ce 0.1 Fe 0.95 Y 0.05 O 3-δ With PrCoO 3-δIV performance curves of a single cell sample formed from the composite material (BCFY0.05-PCO) were obtained under different temperature conditions in a 5% H2O air atmosphere.

[0027] Figure 9 The IP and IV performance curves of the three single-cell test samples BCFY0.05-PCO-L and BCFY0.05-PCO-H were obtained at 800℃ for application performance testing. Detailed Implementation

[0028] The technical concept of this invention lies in providing a method for preparing and applying a reversible solid oxide battery composite air electrode material through the synergistic effect of doping and impregnation strategies. Specifically, the perovskite material Ba0 as the main phase is prepared by the sol-gel method. 0.9 Ce 0.1 Fe 1-x YxO 3-δ (x=0.05, 0.1) and prepare the precursor impregnation solution PrCoO 3-δ As a second-phase material, it effectively improves the ORR / OER activity of the air electrode material and gives it better electrochemical performance by combining the advantages of two-phase materials with the fast oxygen transport pathway at the two-phase heterogeneous interface.

[0029] This invention introduces the metal cation Y to optimize the air electrode BCF material. The large ionic radius of Y ions stabilizes the phase structure of BCF, and the strong hydration capacity of Y ions enhances OER activity. Furthermore, a layer of nanoparticle perovskite material PrCoO2 is synergistically impregnated onto the material. 3-δ The high catalytic activity of the Co group is utilized to synergistically enhance its ORR / OER performance, while the formed three-phase interface also accelerates oxygen adsorption and dissociation. This multi-strategy synergistic effect effectively improves the air electrode electrochemical performance of reversible solid oxide batteries.

[0030] The present invention will be further described in detail below with reference to specific embodiments, so that those skilled in the art can more clearly understand the present invention. The following embodiments are only used to illustrate the present invention, and are not intended to limit the scope of the present invention. Based on the specific embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention. In the embodiments of the present invention, unless otherwise specified, all raw material components are commercially available products well known to those skilled in the art; in the embodiments of the present invention, unless specifically specified, the technical means used are conventional means well known to those skilled in the art.

[0031] Example 1 This embodiment provides a method for preparing an air electrode material, including the following steps: Ba (barium nitrate), Ce (cerium nitrate), Fe (ferric nitrate), and Y (yttrium nitrate) sources were dissolved in deionized water (40 mL) and stirred, with a molar ratio of metal cations, ethylenediaminetetraacetic acid (EDTA), and citric acid of 1:1:1.5. 5.8448 g of EDTA, 6.304 g of citric acid, and 2.9 g of polyethylene glycol were then added. After complete dissolution, ammonia was added to adjust the pH to 7-8, resulting in a raw material solution with a volume of 50 mL and a concentration of 0.4 M (total metal ion concentration).

[0032] The raw material solution was poured into an evaporating dish and placed in a water bath at 80°C for 24 hours to evaporate the water and obtain a gel-like substance.

[0033] The gel-like substance was heated on an induction cooker until it burned into a black precursor. It was then placed in a mortar and ground until there was no obvious particle texture. The mixture was then placed in a muffle furnace and calcined for the first time in an air atmosphere at a heating rate of 3℃ / min for 4 hours to obtain the precursor powder.

[0034] The precursor powder was extruded at 30 MPa for 3 min using a tablet press to form a disc with a diameter of 12 mm. Then, it was placed in a muffle furnace and calcined a second time in an air atmosphere. The heating rate was 5 °C / min below 800 °C and 3 °C / min between 800 and 1100 °C. The calcination was carried out at 1100 °C for 5 h to obtain the main phase perovskite material.

[0035] In this embodiment: When the molar ratio of Ba source (barium nitrate), Ce source (cerium nitrate), Fe source (ferric nitrate), and Y source (yttrium nitrate) is 36:4:39:1, the prepared main phase perovskite material is Ba. 0.9 Ce 0.1 Fe 0.975 Y 0.025 O 3-δ The material is denoted as BCFY0.025.

[0036] When the molar ratio of Ba (barium nitrate), Ce (cerium nitrate), Fe (ferric nitrate), and Y (yttrium nitrate) is 18:2:19:1, with 2.352 g of barium nitrate, 0.43422 g of cerium nitrate, 3.838 g of ferric nitrate, and 0.1915 g of yttrium nitrate, the prepared main phase perovskite material is Ba. 0.9 Ce 0.1 Fe 0.95 Y 0.05 O 3-δ The material is denoted as BCFY0.05.

[0037] When the molar ratio of Ba (barium nitrate), Ce (cerium nitrate), Fe (ferric nitrate), and Y (yttrium nitrate) is 9:1:9:1, with 2.352 g of barium nitrate, 0.43422 g of cerium nitrate, 3.636 g of ferric nitrate, and 0.383 g of yttrium nitrate, the prepared main phase perovskite material is Ba. 0.9 Ce 0.1 Fe 0.9 Y 0.1 O 3-δ The material is denoted as BCFY0.1.

[0038] Example 2: Preparation of precursor impregnation solution PrCoO 3-δ (PCO).

[0039] According to the molar ratio of metal cation and citric acid of 1:1.5, Pr source (praseodymium nitrate, 8.7g) and Co source (cobalt nitrate, 5.82g) were dissolved in 80mL of deionized water at a molar ratio of 1:1 and stirred. 11.53g of citric acid was added and after it was completely dissolved, ammonia water was added and the pH value was adjusted to 7-8 to obtain the raw material solution.

[0040] Transfer the raw material solution to a 100 mL volumetric flask, dilute to volume with deionized water, and mix well to obtain the precursor impregnation solution PrCoO. 3-δ (PCO), where the concentration of Pr ions is 0.2M and the concentration of Co ions is 0.2M.

[0041] Comparative Example 1 This comparative example provides a method for preparing an air electrode material, including the following steps: According to the molar ratio of metal cation, ethylenediaminetetraacetic acid, and citric acid of 1:1:1.5, Ba source (barium nitrate, 2.352g), Ce source (cerium nitrate, 0.43422g), and Fe source (ferric nitrate, 4.04g) were dissolved in 40mL of deionized water and stirred. Then, 5.8448g of ethylenediaminetetraacetic acid, 6.304g of citric acid, and 2.9g of polyethylene glycol were added. After all the solution was dissolved, ammonia water was added to adjust the pH to 7-8, resulting in 50mL of raw material solution.

[0042] The raw material solution was poured into an evaporating dish and placed in a water bath at 80°C for 24 hours to evaporate the water and obtain a gel-like substance.

[0043] The gel-like substance was heated on an induction cooker until it burned into a black precursor. It was then ground in a mortar until there was no obvious particle texture. The mixture was then placed in a muffle furnace and calcined for the first time in an air atmosphere at a heating rate of 3℃ / min for 4 hours to obtain the precursor powder.

[0044] The precursor powder was extruded using a tablet press at 30 MPa for 3 min to form 12 mm diameter discs, which were then placed in a muffle furnace for secondary calcination in an air atmosphere. The heating rate was 5 °C / min below 800 °C and 3 °C / min between 800 and 1100 °C. Calcination was carried out at 1100 °C for 5 h to obtain the air electrode Ba. 0.9 Ce 0.1 FeO 3-δ The material is denoted as BCF.

[0045] The materials prepared in the above experimental examples were subjected to structural characterization analysis: (1) XRD characterization See Figure 1 The materials prepared in the above experimental examples were calcined at 1100℃ in air for 5 hours and then naturally cooled to room temperature. The XRD spectra were measured, showing that the BCF material prepared in Comparative Example 1 had an impurity phase BaFe2O4 during the synthesis process. In Example 1, the impurity phase BaFe2O4 disappeared by adding an appropriate amount of Y source, and a pure perovskite phase was formed.

[0046] The precursor impregnation solution prepared in Example 2 was heated on an induction cooker until completely dry, then placed in a mortar and ground until no obvious particles were felt. Finally, it was calcined at 800°C in air for 2 hours, allowed to cool naturally to room temperature, and the XRD pattern was measured. The results showed that no other impurity phases were produced, indicating that it was pure PrCoO. 3-δ Perovskite phase.

[0047] 20 µL of the precursor impregnation solution prepared in Example 2 was dropped into the material BCFY0.05 ​​prepared in Example 1 (weighed 1 g) to form a BCFY0.05-PCO composite material. After calcination at 800 °C in air for 2 h and natural cooling to room temperature, the XRD spectrum was measured, showing that no other phases were generated, indicating that the change in the performance of the air electrode material after impregnation is only related to PCO.

[0048] Comprehensive analysis: The main phase perovskite materials BCFY0.05 ​​and BCFY0.1 prepared in Example 1 were determined to be pure phase perovskite. The introduction of Y element can eliminate the impurity phase generated during the preparation of BCF in Comparative Example 1. The precursor impregnation solution of Example 2 can form a pure perovskite phase after calcination at 800°C in air for 2 hours. The diffraction peaks of the material BCFY0.05-PCO prepared by combining the precursor impregnation solution PCO with BCFY0.05 ​​can be determined based on the BCFY0.05 ​​phase and PrCoO. 3-δ The phases correspond to each other in the figure, and no other diffraction peaks appear, indicating that BCFY0.05 ​​and PrCoO are the correct phases. 3-δ It has good chemical and structural compatibility.

[0049] (2) SEM characterization The BCFY0.05-PCO material, prepared by combining the precursor impregnation solution PCO with BCFY0.05, was subjected to SEM morphology testing, and the results are as follows: Figure 2 As shown, it can be seen that the second phase PrCoO 3-δ The material is in the form of nanosheets covering large perovskite particles in the main phase.

[0050] Application performance test 1: Preparation of symmetric cell test samples: Air electrode slurry was obtained by mixing 0.0513 g of the air electrode material (main phase perovskite material) prepared in Example 1 and Comparative Example 1 with 0.076 g of binder (a mixture of 90% terpineol and 10% ethyl cellulose).

[0051] The air electrode slurry was coated onto the electrolyte Ce using screen printing (250 mesh screen). 0.8 Gd 0.2 O 3-δ (GDC) Both sides, GDC is a circular piece with a diameter of 13.7mm, dried at 120℃ for 1h, and then sintered at 1000℃ for 2h to obtain a symmetrical battery semi-finished product.

[0052] Using a pipette, 2-3 µL of the precursor impregnation solution PCO prepared in Example 2 was dropped onto the air electrode surfaces on both sides of the symmetrical battery semi-finished product (effective area 0.21 cm²). 2 The sample was dried at 120℃ for 2 hours and then calcined at 800℃ for 2 hours at a heating rate of 4℃ / min to obtain the symmetrical battery sample.

[0053] Electrochemical impedance spectroscopy (EIS) spectra of the above-mentioned symmetrical battery samples were obtained by testing in air and at 800°C, respectively. (See attached image.) Figure 3 It can be seen that: The ASR value of the symmetrical cell based on the BCF air electrode was measured to be 0.151 Ωcm. 2 ; The ASR value of the symmetrical cell based on the BCFY 0.05 air electrode was measured to be 0.10 Ωcm. 2 ; The ASR value of the symmetrical cell based on the BCFY0.1 air electrode was measured to be 0.115 Ωcm. 2 ; The ASR value of the symmetrical cell based on the BCFY0.05-PCO air electrode was measured to be 0.066 Ωcm. 2 ; The ASR value of the symmetrical cell based on the BCFY0.1-PCO air electrode was measured to be 0.087 Ωcm. 2 .

[0054] show: The oxygen reduction activity of the reversible solid oxide battery composite air electrode material, which utilizes the synergistic effects of doping and impregnation strategies, is significantly increased compared to the single-phase air electrode material prepared in Comparative Example 1. Furthermore, the oxygen reduction activity is higher when the Y doping amount is 0.05. However, if the Y doping amount is further increased to 0.1, the oxygen reduction activity decreases instead.

[0055] Application performance test two: Preparation of single-cell test samples: 0.0513g of the air electrode material prepared in Example 1 and Comparative Example 1 were mixed with 0.076g of binder (a mixture of 90% terpineol and 10% ethyl cellulose) to obtain air electrode slurry.

[0056] The air electrode slurry was coated onto the NiO-YSZ / YSZ / GDC electrolyte surface of the half-cell by screen printing (PanHydrogen Power (Shanghai) Technology Co., Ltd.), dried at 120℃ for 1 hour, and then calcined at 1000℃ for 2 hours with a heating rate of 4℃ / min to obtain a single-cell semi-finished product.

[0057] Using a pipette, 2-3 µL of the precursor impregnation solution prepared in Example 2 was dropped onto the air electrode surface of the single-cell semi-finished product (effective area 0.21 cm²). 2 The sample was dried at 120℃ for 2 hours and then calcined at 800℃ for 2 hours at a heating rate of 4℃ / min to obtain the single-cell test sample.

[0058] The IP and IV curves of the fuel cells were obtained by testing the above single-cell test samples under different temperatures (800℃, 750℃, 700℃, 650℃) in air atmosphere.

[0059] See Figure 4 It can be seen that the maximum power density of the BCF-based air electrode fuel cell (NiO-YSZ / YSZ / GDC / BCF) at 800℃, 750℃, 700℃, and 650℃ is 0.60 W / cm³. -2 0.50Wcm -2 0.41Wcm -2 0.31Wcm -2 .

[0060] See Figure 5It can be seen that the maximum power density of the fuel cell (NiO-YSZ / YSZ / GDC / BCFY0.05) based on the BCFY0.05 ​​air electrode is 0.90 W / cm³ at 800℃, 750℃, 700℃, and 650℃. -2 0.78Wcm -2 0.70Wcm -2 0.57Wcm -2 .

[0061] See Figure 6 It can be seen that the maximum power density of the fuel cell based on the BCFY0.05-PCO air electrode (NiO-YSZ / YSZ / GDC / BCFY0.05-PCO) is 1.3 Wcm³ at 800℃, 750℃, 700℃, and 650℃. -2 1.2Wcm -2 1.1Wcm -2 0.95Wcm -2 .

[0062] Further analysis: (1) The maximum power density of the BCF air-electrode fuel cell decreases significantly with decreasing temperature, reaching 0.60 W / cm³ at 800℃. -2 It drops to 0.31 Wcm at 650℃. -2 Its performance is relatively low in the mid-temperature range.

[0063] (2) The maximum power density of the Y-doped modified air electrode material BCFY0.05 ​​is significantly higher than that of BCF at the same temperature: it increases to 0.90 W / cm³ at 800℃. -2 (50% performance improvement compared to BCF air-electrode fuel cells tested at 800℃), reaching 0.57 Wcm at 650℃. -2 (The performance was improved by 84% compared to the BCF air electrode fuel cell at 650℃), indicating that Y element doping can effectively improve the catalytic activity of the electrode, especially in the medium and low temperature range.

[0064] (3) After further introducing PCO nanoparticles, the performance of the BCFY0.05-PCO composite air electrode fuel cell was significantly improved: the maximum power density reached 1.3 W / cm³ at 800℃. -2 It is approximately 117% higher than BCF and approximately 44% higher than BCFY0.05; it still maintains 0.95 W / cm² even at 650℃. -2 Its high output is far superior to the former two.

[0065] In summary, it can be concluded that the BCFY0.05-PCO air electrode modified by a combination of Y doping and impregnation with PCO nanoparticles can significantly improve the power output in fuel cell mode within the medium temperature range (650-800℃).

[0066] See Figure 7 It can be seen that at 1.3V, the electrolytic current density of the BCF-based air electrode electrolytic cell (NiO-YSZ / YSZ / GDC / BCF) at 800℃, 750℃, 700℃, and 650℃ is 0.81Acm⁻¹. -2 0.72Acm -2 0.48Acm -2 0.34Acm -2 .

[0067] See Figure 8 It can be seen that at 1.3V, the electrolytic current density of the electrolytic cell based on the BCFY0.05-PCO air electrode (NiO-YSZ / YSZ / GDC / BCFY0.05-PCO) at 800℃, 750℃, 700℃, and 650℃ is 1.29 Acm⁻¹. -2 1.05Acm -2 0.85Acm -2 0.62Acm -2 .

[0068] Further analysis shows that: The BCFY0.05-PCO composite electrode significantly enhances the kinetics of both the oxygen reduction reaction (ORR, fuel cell mode) and the oxygen evolution reaction (OER, electrolysis mode), exhibiting excellent reversible bifunctional catalytic properties. In the 650–700 °C range, the BCFY0.05-PCO composite electrode shows an improvement of over 80% in both output power density and electrolysis current density compared to BCF, indicating that the synergistic approach of doping and impregnation is particularly suitable for low-to-medium temperature reversible solid oxide batteries (R-SOC), helping to reduce operating temperature, extend lifespan, and lower costs. Y doping optimizes the electronic structure and oxygen vacancy concentration of BCF, improving intrinsic catalytic activity, while the impregnated PCO (PrCoO3-δ) nanoparticles provide highly active ORR / OER sites and form a stable heterostructure with BCFY0.05, expanding the three-phase reaction region and improving charge transfer and gas diffusion. This synergistic approach overcomes the inherent challenge of achieving both activity and stability in traditional cobalt-based perovskites at medium temperatures.

[0069] Application performance test three: Referring to Application Performance Experiment 2, this experiment only adjusts the effect of different amounts of precursor impregnation solution prepared in Example 2 on the performance of the single-cell test sample. The specific experiment is divided into: (1) Using a pipette, take 0.5~1µL of the precursor impregnation solution prepared in Example 2 and drop it onto the air electrode surface of the single-cell semi-finished product (effective area 0.21cm²). 2 The sample was dried at 120℃ for 2 hours and then calcined at 800℃ for 2 hours at a heating rate of 4℃ / min. The sample was then sintered at 800℃ for 2 hours to obtain a single cell sample, which was denoted as NiO-YSZ / YSZ / GDC / BCFY0.05-PCO-L (abbreviated as BCFY0.05-PCO-L).

[0070] (2) Using a pipette, take 6-7 µL of the precursor impregnation solution prepared in Example 2 and drop it onto the air electrode surface of the single-cell semi-finished product (effective area 0.21 cm²). 2 The sample was dried at 120℃ for 2 hours and then calcined at 800℃ for 2 hours at a heating rate of 4℃ / min. The sample was then sintered at 800℃ for 2 hours to obtain a single cell sample, which was denoted as NiO-YSZ / YSZ / GDC / BCFY0.05-PCO-H (abbreviated as BCFY0.05-PCO-H).

[0071] The IP and IV curves of the fuel cells were obtained by testing the above single-cell test samples under an air atmosphere temperature of 800℃.

[0072] See results Figure 9 It can be seen that: The fuel cell based on the BCFY0.05-PCO-L air electrode has a maximum power density of 1.04 W / cm³ at 800℃. -2 The fuel cell based on the BCFY0.05-PCO-H air electrode has a maximum power density of 1.01 W / cm³ at 800℃. -2 .

[0073] The above results are compared with those of the BCFY 0.05-PCO air electrode (800℃, 1.3Wcm). -2 The significant difference indicates that the PCO loading has a certain impact on performance. BCFY0.05-PCO-L, due to insufficient PCO nanoparticles and limited active sites, cannot fully enhance the oxygen reduction reaction (ORR) kinetics, resulting in suboptimal performance. Conversely, BCFY0.05-PCO-H, due to excessive PCO particles clogging electrode pores, hindering gas diffusion, and increasing electrode thickness, actually offsets the catalytic gain, resulting in performance comparable to or even slightly lower than BCFY0.05-PCO-L.

[0074] Comprehensive analysis shows that: The preferred concentration of the impregnation solution is 0.4M, and the amount of BCFY0.05 ​​material electrode layer used per square centimeter is 5~20µL. This air electrode preparation ratio perfectly balances the relationship between catalytic activity, microstructure and gas transport, and maximizes synergistic effect.

[0075] It should be noted that the above embodiments are only for further elaboration and explanation of the technical solution of the present invention, and are not intended to further limit the technical solution of the present invention. The method of the present invention is only a preferred embodiment and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An air electrode, characterized in that, It is mainly made of material A and material B; Wherein, material A is Ba 1-x Ce x Fe 1-y Y y O 3-δ And the range of x is: 0 < x ≤ 0.1, the range of y is: 0 < y ≤ 0.1, and the range of δ is 0 < δ ≤ 0.5; Material B is PrCoO 3-δ Material.

2. The air electrode according to claim 1, characterized in that, The preparation method of material A includes: Prepare precursor solutions containing Ba, Ce, Fe, and Y sources, with a pH of 7-8; The precursor solution was evaporated to prepare a gel-like substance; The gel-like substance was heated and burned into a black precursor, which was then ground and placed in an air atmosphere for initial calcination to obtain a primary calcined powder. The primary calcined powder was compressed into tablets and then subjected to secondary calcination in air, followed by grinding to obtain Ba. 1-x Ce x Fe 1- y Y y O 3-δ Powder materials.

3. The air electrode according to claim 2, characterized in that, The precursor solution also contains ethylenediaminetetraacetic acid and citric acid, with the molar ratio of the metal cation, ethylenediaminetetraacetic acid, and citric acid being 1:1:1.

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4. The air electrode according to claim 2 or 3, characterized in that, In the step of preparing material A, the primary calcination temperature is 600°C and the duration is 4 hours.

5. The air electrode according to claim 2 or 3, characterized in that, In the step of preparing material A, the secondary calcination temperature is 1100℃ and the duration is 5h.

6. The air electrode according to claim 1, characterized in that, Material B is prepared by drying and sintering a solution containing Pr and Co sources.

7. A method for preparing an air electrode, characterized in that, Includes the following steps: Prepare an air electrode slurry comprising material A as described in any one of claims 1 to 6; The air electrode slurry is coated on the surface of the electrolyte structure layer, dried and sintered for the first time to form electrode layer A. An impregnation solution containing Pr source and Co source is prepared, and the surface of electrode layer A is impregnated. The surface is then dried and sintered to obtain an air electrode composite layer containing material B of any one of claims 1 to 6.

8. The method for preparing the air electrode according to claim 7, characterized in that, The concentration of the impregnation solution is 0.4M, and the amount of electrode layer A used per square centimeter is 5~20µL.

9. The method for preparing the air electrode according to claim 7, characterized in that, The process parameters for initial drying and sintering are: sintering at 1000℃ for 2 hours; The process parameters for secondary drying and sintering are: sintering at 800℃ for 2 hours.

10. The use of the air electrode according to any one of claims 7 to 9 in the preparation of a reversible solid oxide battery.

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