Perovskite electrode material for reversible sofc-soec and method for preparing the same

Abstract

The application belongs to the technical field of solid oxide cell electrode materials, and particularly relates to a perovskite structure electrode material for reversible SOFC-SOEC and a preparation method thereof. 1‑a Ba a Co 1‑(x+y) Fe x Ni y O 3‑δ and a second perovskite phase La 1‑c Sr c Ga 1‑d Mg d O 3‑δ are compounded. The preparation method comprises synthesizing two-phase powders respectively, preparing slurry and coating by using a specific compound type amphiphilic dispersant, and finally co-sintering and forming by heat treatment. By constructing a three-dimensional network of two-phase mutual penetration, the chemical expansion stress of the electrode in reversible operation is effectively relieved, high catalytic activity and fast ion conduction are ensured, and therefore the electrochemical performance and long-term cycle stability of the electrode in the SOFC and SOEC dual mode are significantly improved.

Description

Technical Field

[0001] This invention belongs to the field of solid oxide battery electrode materials technology, specifically relating to a perovskite structure electrode material for reversible SOFC-SOEC and its preparation method. Background Technology

[0002] Solid oxide fuel cells (SOFCs) and solid oxide electrolyzers (SOECs), as efficient and clean energy conversion and storage devices, are considered key technologies for achieving large-scale utilization of renewable energy and grid peak shaving in the future, particularly in their integrated reversible system (R-SOC). This system can function as an electrolyzer (SOEC mode) to convert water or carbon dioxide into fuel when there is a power surplus, and as a fuel cell (SOFC mode) to efficiently convert the stored fuel chemical energy into electrical energy when there is a power shortage, thus achieving cross-temporal and spatial energy storage and dispatch. This "two-way" capability places extremely stringent requirements on core stack components, especially electrode materials: the electrode materials must be exposed alternately to strong oxidizing and reducing atmospheres at high temperatures while continuously maintaining high catalytic activity, rapid ion / electron conduction capabilities, and excellent structural and interfacial stability.

[0003] Currently, the research and development of electrode materials for reversible SOC mainly revolves around perovskites and their derived structures, seeking to replace or improve traditional nickel-based cermet materials. Existing technological approaches can be broadly summarized into three directions: First, elemental doping at the A-site or B-site of a single perovskite phase aims to enhance its intrinsic activity and stability by adjusting the oxygen vacancy concentration and electronic structure. Examples include developing various cobalt- and iron-based perovskites as air electrodes, or chromium- and manganese-based perovskites as fuel electrodes. Second, employing an "in-situ precipitation" strategy, under a specific reducing atmosphere, transition metal elements doped at the B-site of perovskite are precipitated from the matrix as nano-alloy particles and anchored on the surface, forming a perovskite-metal composite structure, with the aim of significantly improving the catalytic activity of the fuel oxidation reaction. Third, surface modification or the construction of composite structures, such as loading nanoscale oxides or metal particles onto the perovskite surface through impregnation, hydrothermal methods, etc., attempting to construct multifunctional active interfaces.

[0004] Despite the significant progress made in the aforementioned research, existing technologies still face a deep-seated contradiction and common challenge in long-term, high-power-density reversible cycling: the inherent conflict between "high electrochemical activity" and "long-term structural stability." To achieve high activity, material design often incorporates a large number of variable-valence metal ions or precipitates highly active nano-metal particles through reduction. However, in the inherent redox atmosphere of reversible operation, these active components undergo significant lattice oxygen insertion / extraction, valence state changes of metal ions, and even phase formation and disappearance. This process inevitably triggers substantial lattice volume expansion and contraction in the bulk material. Repeated, periodic volume changes accumulate enormous mechanical stress within the electrode material, between electrode particles, and at the crucial electrode-electrolyte interface. Under long-term effects, this stress inevitably leads to microcracks in the electrode microstructure, coarsening and agglomeration of active nanoparticles, and delamination or peeling at the electrode layer and electrolyte support interface. These problems ultimately manifest as accelerated degradation of battery output performance during reversible cycling, with the operating life far from meeting the requirements for commercial applications. It is particularly noteworthy that the currently commonly used physical-mechanical mixing or simple surface modification methods, while improving the initial performance to some extent, are difficult to achieve synergy and stress buffering of active and stable components in three-dimensional space at the atomic / nanoscale, and cannot effectively suppress the destructive consequences caused by the aforementioned bulk chemical expansion effect.

[0005] Therefore, developing a new type of electrode material that can reconcile the contradiction between activity and stability from the intrinsic design of the material, especially one that can effectively resist the volume stress caused by repeated redox cycles, thereby ensuring long-term reliable operation, has become a key bottleneck that urgently needs to be overcome to promote the practical application of reversible solid oxide battery technology. Summary of the Invention

[0006] The purpose of this invention is to provide a perovskite structure electrode material for reversible SOFC-SOEC and its preparation method, in order to solve the problem of structural damage and performance degradation caused by chemical expansion in existing electrode materials during long-term, high-power-density reversible cycling. The aim is to achieve a balance between catalytic activity and structural stability of the electrode material, thereby significantly improving the cycle life and operational reliability of reversible solid oxide batteries.

[0007] To achieve the above objectives, the present invention provides the following technical solution: The first aspect of this invention provides a perovskite-structured electrode material for reversible SOFC-SOEC, the material being a biphase perovskite composite with a three-dimensional interpenetrating network structure; The dual-phase perovskite complex is composed of a first perovskite phase and a second perovskite phase, wherein: the chemical formula of the first perovskite phase is: Pr1-a Ba a Co 1-(x+y) Fe x Ni y O 3-δ Where 0.4≤a≤0.6, 0.05≤x≤0.25, 0.05≤y≤0.25, and x+y≤0.3, and δ is the non-stoichiometric number of oxygen vacancies; The general chemical formula of the second perovskite phase is: La 1-c Sr c Ga 1-d Mg d O 3-δ , where 0.1≤c≤0.3, 0.1≤d≤0.3, and δ is the non-stoichiometric number of oxygen vacancies.

[0008] Furthermore, the three-dimensional interpenetrating network structure refers to the first perovskite phase and the second perovskite phase each forming a continuous three-dimensional skeleton in space, with the two skeletons intertwined and penetrating each other to form a dual continuous phase composite.

[0009] Furthermore, the dry basis mass ratio of the first perovskite phase to the second perovskite phase is (40:60) to (70:30).

[0010] Furthermore, the open porosity of the dual-phase perovskite composite is 20%~40%.

[0011] The advantages of the electrode material of this invention stem from the synergistic solution of intrinsic material contradictions by its three-dimensional interpenetrating network structure. The first perovskite phase provides high electrocatalytic activity and electronic conduction, but it undergoes harmful chemical volume expansion during redox cycles. The second perovskite phase, on the other hand, possesses a stable lattice and high oxygen ion conductivity. The two phases form a nanoscale bicontinuous interpenetrating network. This structure effectively constrains the volume changes of the active first phase in three-dimensional space through the stable second-phase framework, transforming localized concentrated stress into uniformly distributed elastic stress, thereby suppressing the destruction of the electrode microstructure and crack propagation. Simultaneously, the continuous second-phase network constructs a rapid oxygen ion transport channel penetrating the electrode bulk phase, reducing transport polarization. Furthermore, this topology maximizes and firmly binds the two-phase interface, forming an extended and stable three-phase reaction interface. This not only enhances the initial reaction kinetics but also prevents the migration and aggregation of active phase nanoparticles during long-term high-temperature operation through physical separation and anchoring, ensuring the number and stability of active sites. Therefore, while maintaining high activity, the material's structural integrity, charge transport efficiency, and electrochemical interface are synergistically maintained under harsh reversible cycling, achieving long-term performance stability.

[0012] A second aspect of the present invention provides a method for preparing the above-mentioned perovskite structure electrode material for reversible SOFC-SOEC, comprising the following steps: (1) According to the general chemical formula Pr 1-a Ba a Co 1-(x+y) Fe x Ni y O 3-δ The corresponding metal salts were weighed according to the stoichiometric ratio, and the precursors were prepared by the sol-gel method. After drying and calcination, the first perovskite phase powder was obtained. According to the general chemical formula La 1-c Sr c Ga 1-d Mg d O 3-δ Weigh the corresponding metal salts according to their stoichiometric ratio, mix them, and calcine them to obtain the second perovskite phase powder. (2) The first perovskite phase powder and the second perovskite phase powder are mixed in proportion and added to an organic solvent containing an amphiphilic dispersant. The mixture is ball-milled into a slurry and coated onto an electrolyte substrate to form a wet film. (3) The electrolyte substrate coated with wet film is first heated to 400-600℃ and kept at that temperature; then heated to 1150-1250℃ and kept at that temperature; then cooled to room temperature to form a two-phase perovskite composite with a three-dimensional interpenetrating network structure on the electrolyte substrate, which is the electrode material.

[0013] Further, in step (1) when preparing the first perovskite phase powder, the sol-gel method specifically involves: dissolving the metal salt in deionized water, adding a complexing agent, wherein the molar ratio of the complexing agent to the total metal ions is (1.5-3.0):1, stirring and evaporating at 60-90℃ until a gel is formed, and then drying at 80-120℃ to obtain a dry gel precursor; wherein the complexing agent is one or more of citric acid, ethylenediaminetetraacetic acid, or tartaric acid; and wherein the calcination temperature is 900-1100℃.

[0014] Further, in step (1) when preparing the second perovskite phase powder, the calcination is carried out in stages: first, the temperature is raised to 1000-1200℃ at 3-5℃ / min and held for 2-6 hours for pre-synthesis, then ground and calcined at the same rate to 1300-1450℃ for 5-12 hours to obtain the second perovskite phase powder.

[0015] Further, the amphiphilic dispersant in step (2) comprises 40%-60% hydrogenated castor oil, 20%-35% lecithin, and 15%-30% polyvinylpyrrolidone.

[0016] Further, the organic solvent in step (2) is a mixture of terpineol and anhydrous ethanol, wherein the volume ratio of terpineol to anhydrous ethanol is (7:3)-(9:1).

[0017] Further, the mass concentration of the amphiphilic dispersant in the organic solvent in step (2) is 1.0%-3.0%; the total amount of the amphiphilic dispersant added is 1.0%-4.0% of the total mass of the first and second perovskite phase powders.

[0018] Further, in step (3), the temperature is increased to 400-600℃ at a rate of 0.5-2℃ / min and held for 1-3 hours; then, the temperature is increased to 1150-1250℃ at a rate of 2-5℃ / min and held for 2-5 hours.

[0019] The preparation method of this invention utilizes a dispersant composed of hydrogenated castor oil, lecithin, and polyvinylpyrrolidone in a specific ratio to precisely pre-assemble the microstructures of two powders with distinctly different surface properties—the first and second perovskite phases—during the slurry preparation stage. This dispersant system selectively adsorbs onto the surfaces of different powders, effectively controlling their surface energy and dispersion state. During solvent evaporation and slurry formation, it guides the two phases to form a uniform, interwoven spatial distribution rather than agglomeration or macroscopic stratification. This specific precursor microstructure induced by the dispersant is the decisive basis for the formation of continuous three-dimensional networks in each phase during subsequent co-sintering, ultimately resulting in mutual penetration and locking. The method of this invention avoids the complex and difficult-to-control in-situ phase separation process, directly and reliably constructing a bipolar interpenetrating network electrode structure through a relatively simple and controllable slurry process.

[0020] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: The perovskite-structured electrode material and its preparation method provided by this invention successfully solve the problem of activity decay and structural damage caused by chemical expansion in existing electrodes during long-term reversible cycling by designing and constructing an interpenetrating network structure of a first perovskite phase and a second perovskite phase in three-dimensional space. This unique structure allows the highly active first phase and the highly stable second phase to support and constrain each other, effectively buffering the volume stress generated by switching between redox atmospheres and suppressing the generation and propagation of microcracks. Simultaneously, the two phases each form continuous electron and ion transport channels, ensuring efficient electrochemical reaction kinetics. The specific compound dispersant and preparation process used are key to achieving this ideal microstructure, enabling the electrode to exhibit high power density in SOFC mode and high electrolysis current density in SOEC mode. Particularly noteworthy is its extremely low performance decay rate in stringent reversible cycling tests, achieving an essential unity of catalytic activity and structural stability, and possessing significant application value. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Unless otherwise specified, all raw materials used in the examples are commercially available products.

[0023] Example 1 This embodiment provides a perovskite structure electrode material for reversible SOFC-SOEC, the preparation method of which includes the following steps: (1) First perovskite phase powder (Pr 0.5 Ba 0.5 Co 0.8 Fe 0.1 Ni 0.1 O 3-δ Preparation of ) Accurately weigh Pr(NO3)3·6H2O, Ba(NO3)2, Co(NO3)2·6H2O, Fe(NO3)3·9H2O, and Ni(NO3)2·6H2O according to stoichiometric ratio, and dissolve them in deionized water. Add citric acid as a complexing agent, with a molar ratio of citric acid to total metal ions of 2:1. Stir continuously and evaporate in an 80℃ constant temperature water bath until the solution transforms into a viscous gel. Place the gel in an oven and dry at 100℃ for 12 hours to obtain a dry gel precursor. Place the precursor in a muffle furnace and calcine it to 1000℃ at a rate of 3℃ / min in air atmosphere for 5 hours. After natural cooling, grind to obtain the first perovskite phase powder.

[0024] Second perovskite phase powder (La) 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3-δ Preparation of ) Accurately weigh La₂O₃ (pre-calcined at 900℃), SrCO₃, Ga₂O₃, and MgO according to stoichiometric ratio. Mix the raw materials with anhydrous ethanol and place them in a planetary ball mill jar, ball-milling at 300 rpm for 10 hours. After drying the ball-milled slurry, pre-calcine it at 1100℃ for 4 hours under air atmosphere at a heating rate of 3℃ / min. After pre-calcining, grind the powder again and calcine it at 1400℃ at the same heating rate for 8 hours. After natural cooling, the second perovskite phase powder is obtained.

[0025] (2) Weigh and mix the first perovskite phase powder and the second perovskite phase powder at a dry basis mass ratio of 55:45. Prepare the organic solvent: mix terpineol and anhydrous ethanol at a volume ratio of 8:2. Prepare the compound amphiphilic dispersant: mix 50% hydrogenated castor oil, 25% lecithin and 25% polyvinylpyrrolidone by mass percentage. Add the compound dispersant to the above organic solvent at a mass of 2.5% of the total powder mass, stir to dissolve fully, and obtain a solution with a dispersant concentration of 2.0 wt%.

[0026] The mixed powder was added to a solvent containing a dispersant, and the mixture was placed in a planetary ball mill jar and ball-milled at 350 rpm for 10 hours to obtain an electrode paste. The paste was then coated onto a dense La234 surface using screen printing technology. 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3-δ On one side of the (LSGM) electrolyte sheet, the wet film thickness is controlled by the mesh count of the screen and then dried at 80°C.

[0027] (3) The coated semi-finished product is placed in a muffle furnace for heat treatment. First, the temperature is raised to 500°C at a heating rate of 1°C / min and held for 2 hours to completely remove organic matter from the slurry. Then, the temperature is raised to 1200°C at a heating rate of 3°C / min and held at this temperature for 3 hours for co-sintering. After sintering, the temperature is slowly cooled to room temperature at a cooling rate of no more than 2°C / min to obtain the perovskite structure electrode material for reversible SOFC-SOEC.

[0028] Example 2 This embodiment provides a perovskite structure electrode material for reversible SOFC-SOEC, the preparation method of which includes the following steps: (1) First perovskite phase powder (Pr 0.6 Ba 0.4 Co 0.75 Fe 0.15 Ni 0.1 O 3-δ Preparation of ) Accurately weigh Pr(NO3)3·6H2O, Ba(NO3)2, Co(NO3)2·6H2O, Fe(NO3)3·9H2O, and Ni(NO3)2·6H2O according to stoichiometric ratio, and dissolve them in deionized water. Add a mixed complexing agent of ethylenediaminetetraacetic acid (EDTA) and citric acid (molar ratio 1:1), with a total molar ratio of complexing agent to total metal ions of 2.5:1. Stir and evaporate in a constant temperature water bath at 75℃ until a gel is formed. Place the gel in an oven and dry at 110℃ for 10 hours to obtain a dry gel precursor. Calcinate the precursor in air at a rate of 5℃ / min to 950℃ for 6 hours, allow it to cool naturally, and then grind it to obtain the first perovskite phase powder.

[0029] Second perovskite phase powder (La) 0.85 Sr 0.15 Ga 0.85 Mg 0.15 O 3-δ Preparation of ) Pre-calcined La₂O₃, SrCO₃, Ga₂O₃, and MgO were accurately weighed according to stoichiometric ratios. The raw materials were mixed with anhydrous ethanol and ball-milled for 12 hours (350 rpm). After drying the slurry, it was pre-calcined for 3 hours at 1050°C with a heating rate of 4°C / min in air. After grinding, it was calcined for 10 hours at the same rate to 1350°C to obtain the second perovskite phase powder.

[0030] (2) Weigh and mix the first perovskite phase powder and the second perovskite phase powder at a dry basis mass ratio of 60:40. Prepare an organic solvent: mix terpineol and anhydrous ethanol at a volume ratio of 7.5:2.5. Prepare a compound amphiphilic dispersant: take 45% hydrogenated castor oil, 30% lecithin and 25% polyvinylpyrrolidone by mass percentage. Add the compound dispersant to the organic solvent at a mass of 3.0% of the total powder mass to obtain a solution with a dispersant concentration of 2.5 wt%.

[0031] The mixed powder was added to the above solution and ball-milled for 12 hours (400 rpm) to obtain a slurry. The slurry was then coated onto a dense La234 substrate using screen printing technology. 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3-δ (LSGM) Electrolyte sheet, dried at 80°C.

[0032] (3) The coated semi-finished product is placed in a muffle furnace. First, the temperature is increased to 550°C at 1.5°C / min and held for 1.5 hours to remove organic matter. Then, the temperature is increased to 1180°C at 4°C / min and held for 4 hours for co-sintering. After sintering, the material is cooled to room temperature at a rate not exceeding 2.5°C / min to obtain the electrode material.

[0033] Example 3 This embodiment provides a perovskite structure electrode material for reversible SOFC-SOEC, the preparation method of which includes the following steps: (1) First perovskite phase powder (Pr 0.4 Ba 0.6 Co 0.85 Fe 0.05 Ni 0.1 O 3-δ Preparation of ) Accurately weigh Pr(NO3)3·6H2O, Ba(NO3)2, Co(NO3)2·6H2O, Fe(NO3)3·9H2O, and Ni(NO3)2·6H2O according to the stoichiometric ratio, and dissolve them in deionized water. Tartaric acid is added as a complexing agent, with a molar ratio of tartaric acid to total metal ions of 1.8:1. The mixture is continuously stirred and evaporated in an 85℃ constant temperature water bath until a gel is formed. The gel is placed in an oven and dried at 90℃ for 15 hours to obtain a dry gel precursor. This precursor is placed in a muffle furnace and calcined at 1100℃ at a rate of 2℃ / min in air atmosphere for 3.5 hours. After natural cooling, it is ground to obtain the first perovskite phase powder.

[0034] Second perovskite phase powder (La) 0.9 Sr 0.1 Ga 0.9 Mg 0.1 O 3-δ Preparation of ) Pre-calcined La₂O₃, SrCO₃, Ga₂O₃, and MgO were accurately weighed according to stoichiometric ratios. The raw materials were mixed with anhydrous ethanol and placed in a planetary ball mill jar, where they were ball-milled at 320 rpm for 8 hours. After the slurry was dried, it was pre-calcined in air at a rate of 3°C / min to 1150°C for 2 hours. The pre-calcined powder was then ground and calcined at the same rate to 1300°C for 12 hours. After natural cooling, the second perovskite phase powder was obtained.

[0035] (2) Weigh and mix the first perovskite phase powder and the second perovskite phase powder at a dry basis mass ratio of 50:50. Prepare the organic solvent: mix terpineol and anhydrous ethanol at a volume ratio of 7:3. Prepare the compound amphiphilic dispersant: mix 55% hydrogenated castor oil, 20% lecithin and 25% polyvinylpyrrolidone by mass percentage. Add the compound dispersant to the above organic solvent at a mass of 1.5% of the total powder, stir to dissolve, and obtain a solution with a dispersant concentration of 1.2 wt%.

[0036] The mixed powder was added to a solvent containing a dispersant, and the mixture was placed in a planetary ball mill jar and ball-milled at 380 rpm for 8 hours to obtain a uniform electrode slurry. The slurry was then coated onto a dense La234 electrode using screen printing technology. 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3-δ On one side of the (LSGM) electrolyte sheet, the wet film thickness is controlled by the mesh count of the screen and then dried at 80°C.

[0037] (3) The coated semi-finished product was placed in a muffle furnace for heat treatment. First, the temperature was raised to 450°C at a heating rate of 0.8°C / min and held for 2.5 hours to completely remove organic matter. Then, the temperature was raised to 1220°C at a heating rate of 2°C / min and held at this temperature for 2 hours for co-sintering. After sintering, the temperature was slowly cooled to room temperature at a cooling rate of no more than 1.5°C / min to obtain the perovskite structure electrode material for reversible SOFC-SOEC.

[0038] Comparative Example 1 The difference between this comparative example and Example 1 is that the hydrogenated castor oil in step (2) is replaced with triethanolamine oleate.

[0039] Comparative Example 2 The difference between this comparative example and Example 1 is that the compound amphiphilic dispersant in step (2) is 60% hydrogenated castor oil and 40% lecithin.

[0040] Comparative Example 3 The difference between this comparative example and Example 1 is that the compound amphiphilic dispersant in step (2) is 20% hydrogenated castor oil, 55% lecithin and 25% polyvinylpyrrolidone.

[0041] Comparative Example 4 The difference between this comparative example and Example 1 is that the first perovskite phase is replaced with Pr 0.5 Ba 0.5 Co 0.9 Fe 0.1 O 3-δ Its preparation method is the same as that in Example 1.

[0042] Comparative Example 5 The difference between this comparative example and Example 1 is that the second perovskite phase is replaced with Zr. 0.92 Y 0.08 O 1.96 Its preparation method is the same as that in Example 1.

[0043] Performance testing 1. Single-cell fabrication: The LSGM electrolyte sheet with a fuel electrode layer prepared in the above embodiments and comparative examples was used as the half-cell substrate. A layer of La2O3 electrolyte was symmetrically coated and sintered onto the other side of the substrate. 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (LSCF) and Gd 0.1 Ce 0.9 O 1.95 (GDC) oxygen electrode slurry is compounded in a 1:1 mass ratio and then sintered twice to form a complete sandwich structure single cell for subsequent performance testing.

[0044] 2. Electrochemical Performance Testing: Tests were conducted at 750℃ using an electrochemical workstation. SOFC mode: Fuel electrode was 97% H₂-3% H₂O, oxygen electrode was air. Current-voltage (IV) curves were recorded and the maximum power density was calculated. Electrochemical impedance spectroscopy (EIS) was performed at open-circuit voltage to obtain the total polarization resistance (Rp). SOEC mode: Fuel electrode was 80% H₂O-20% H₂, oxygen electrode was air. IV curves were recorded and the current density at 1.3V was read.

[0045] 3. Cyclic stability test: The single cell was subjected to periodic current cycling at 750°C. Each cycle included: in SOFC mode at -0.5 A cm⁻¹ -2 Constant current discharge for 1 hour, then immediately switched to SOEC mode at +0.5 A cm⁻¹. -2 Constant current electrolysis for 1 hour. Record the voltage at each cycle switching point, and continuously test for 100 hours to calculate the voltage decay rate.

[0046] The test results are shown in Table 1.

[0047] Table 1 Performance Test Results As can be seen from the above performance test results, Examples 1-3 all exhibit excellent comprehensive performance. The prepared electrode materials have high power density and electrolytic current density, low polarization resistance and extremely low cycle voltage decay rate, which proves that the electrodes have excellent structural stability and durability.

[0048] Comparative Example 1 showed a comprehensive performance decline, indicating that replacing the key component of the compound dispersant, hydrogenated castor oil, with triethanolamine oleate failed to effectively induce the formation of an ideal bipolar interpenetrating network. This resulted in insufficient bonding strength and stress buffering capacity, leading to a significant deterioration in various properties. Comparative Examples 2 and 3 both disrupted the synergistic effect of the compound dispersant, resulting in poor dispersion and assembly of the two-phase powders in the slurry. Ultimately, the uniformity of the electrode's microstructure and the continuity of the two phases were impaired, affecting activity and stability. Comparative Example 4 exhibited the most significant SOFC performance decline. This was due to the complete removal of Ni from the first phase, which significantly reduced the intrinsic electrocatalytic activity and electronic conductivity of the material for hydrogen oxidation, leading to slow electrode reaction kinetics and increased polarization resistance. Comparative Example 5 showed the worst cycle stability and the highest decay rate. This may be because replacing LSGM with YSZ as the second phase resulted in a mismatch in the thermal expansion coefficients between the two phases, and a potential reaction at the high-temperature reduction / oxidation interface. The weak interfacial bonding strength made the interface prone to microcrack formation and propagation under cyclic stress, leading to a sharp increase in contact resistance and rapid performance degradation.

[0049] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A perovskite structure electrode material for reversible SOFC-SOEC, characterized in that, The material is a biphase perovskite composite with a three-dimensional interpenetrating network structure. The dual-phase perovskite complex is composed of a first perovskite phase and a second perovskite phase, wherein: the chemical formula of the first perovskite phase is: Pr 1-a Ba a Co 1-(x+y) Fe x Ni y O 3-δ Where 0.4≤a≤0.6, 0.05≤x≤0.25, 0.05≤y≤0.25, and x+y≤0.3, and δ is the non-stoichiometric number of oxygen vacancies; The general chemical formula of the second perovskite phase is: La 1-c Sr c Ga 1-d Mg d O 3-δ , where 0.1≤c≤0.3, 0.1≤d≤0.3, and δ is the non-stoichiometric number of oxygen vacancies.

2. The perovskite structure electrode material for reversible SOFC-SOEC according to claim 1, characterized in that, The dry basis mass ratio of the first perovskite phase to the second perovskite phase is (40:60) to (70:30).

3. The perovskite structure electrode material for reversible SOFC-SOEC according to claim 1, characterized in that, The open porosity of the dual-phase perovskite composite is 20%~40%.

4. The method for preparing the perovskite structure electrode material for reversible SOFC-SOEC according to any one of claims 1-3, characterized in that, Includes the following steps: (1) According to the general chemical formula Pr 1-a Ba a Co 1-(x+y) Fe x Ni y O 3-δ The corresponding metal salts were weighed according to the stoichiometric ratio, and the precursors were prepared by the sol-gel method. After drying and calcination, the first perovskite phase powder was obtained. According to the general chemical formula La 1-c Sr c Ga 1-d Mg d O 3-δ Weigh the corresponding metal salts according to their stoichiometric ratio, mix them, and calcine them to obtain the second perovskite phase powder. (2) The first perovskite phase powder and the second perovskite phase powder are mixed in proportion and added to an organic solvent containing an amphiphilic dispersant. The mixture is ball-milled into a slurry and coated onto an electrolyte substrate to form a wet film. (3) The electrolyte substrate coated with wet film is first heated to 400-600℃ and kept at that temperature; then heated to 1150-1250℃ and kept at that temperature; then cooled to room temperature to form a two-phase perovskite composite with a three-dimensional interpenetrating network structure on the electrolyte substrate, which is the electrode material.

5. The preparation method according to claim 4, characterized in that, In step (1), when preparing the first perovskite phase powder, the sol-gel method is specifically as follows: the metal salt is dissolved in deionized water, a complexing agent is added, the molar ratio of the complexing agent to the total metal ions is (1.5-3.0):1, the mixture is stirred and evaporated at 60-90℃ to form a gel, and then dried at 80-120℃ to obtain a dry gel precursor; the complexing agent is one or more of citric acid, ethylenediaminetetraacetic acid or tartaric acid; the calcination temperature is 900-1100℃.

6. The preparation method according to claim 4, characterized in that, In step (1), when preparing the second perovskite phase powder, the calcination is carried out in stages: first, the temperature is raised to 1000-1200℃ at 3-5℃ / min and held for 2-6 hours for pre-synthesis, then ground and calcined at the same rate to 1300-1450℃ for 5-12 hours to obtain the second perovskite phase powder.

7. The preparation method according to claim 4, characterized in that, The amphiphilic dispersant in step (2) contains 40%-60% hydrogenated castor oil, 20%-35% lecithin, and 15%-30% polyvinylpyrrolidone.

8. The preparation method according to claim 4, characterized in that, The organic solvent in step (2) is a mixture of terpineol and anhydrous ethanol, wherein the volume ratio of terpineol to anhydrous ethanol is (7:3)-(9:1).

9. The preparation method according to claim 4, characterized in that, The mass concentration of the amphiphilic dispersant in the organic solvent in step (2) is 1.0%-3.0%; the total amount of the amphiphilic dispersant added is 1.0%-4.0% of the total mass of the first and second perovskite phase powders.

10. The preparation method according to claim 4, characterized in that, In step (3), the temperature is increased to 400-600℃ at a rate of 0.5-2℃ / min and held for 1-3 hours; then, the temperature is increased to 1150-1250℃ at a rate of 2-5℃ / min and held for 2-5 hours.

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