Solid oxide fuel cell composite cathode material resisting CO2 poisoning as well as preparation method and application of solid oxide fuel cell composite cathode material

Abstract

The invention discloses an anti-CO2 poisoning solid oxide fuel cell composite cathode material as well as a preparation method and application thereof, and relates to the technical field of fuel cells. The chemical general formula of the raw material composition of the composite cathode material is Pr < x > Sr < 0.6 > Co < 0.5 > Fe < 0.5 > O < 3-delta >, and x is equal to 1.0-1.5. The introduction amount of the second-phase Pr6O11 material can be regulated and controlled by controlling the addition amount of the Pr element. The in-situ self-assembly composite mode enhances the interface bonding force between phases, and improves the structural stability of the electrode in the working process. The Pr6O11 promotes surface oxygen adsorption and dissociation, the Rp phase realizes multiple oxygen transmission through rock salt layer gap replacement and perovskite layer vacancy diffusion, and the Pr6O11 and the Rp phase cooperate to promote the oxygen reduction reaction process. The high acidity of Pr < 3 + > / 4 < + > cations inhibits the reaction that alkaline earth metal oxides form carbonate on the surface, and excellent CO2 resistance is shown.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular to a CO2-poisoning-resistant solid oxide fuel cell composite cathode material, a preparation method thereof, and applications thereof. Background Art

[0002] Solid oxide fuel cells (SOFCs) have attracted widespread attention due to their diverse fuel cell offerings, high efficiency, and environmental friendliness. However, excessively high operating temperatures accelerate the aging of various cell components, severely limiting the commercialization of SOFCs. Lowering the SOFC operating temperature can lead to insufficient kinetics for the oxygen reduction reaction (ORR) at the cathode. Furthermore, cathode materials containing alkaline earth metals are subject to CO2 poisoning. On the one hand, O2 and CO2 compete for active oxygen vacancies on the cathode surface, with CO2 occupying surface oxygen vacancies and reducing ORR activity. On the other hand, the alkaline and alkaline earth elements present in the cathode react with the acidic CO2. Under the influence of CO2, the alkaline earth metals segregate to the surface and react with CO2 to form carbonates, which cover the surface active sites, hindering the adsorption and activation of O2 and the exchange of oxygen ions. Furthermore, the toxicity to ORR activity increases over time. Therefore, designing efficient and stable cathode materials is crucial for the further development of SOFCs.

[0003] Currently, the general formula is A n+1 B n O 3n+1 Ruddlesden-Popper (RP) oxides, a layered (2D) structure (A = rare earth; B = transition metal) with a 2D structure, have attracted widespread attention. Structurally, this family has been shown to adopt a simple tetragonal structure (I4 / mmm), with an internal structure consisting of alternating perovskite ABO3 layers and rock salt AO layers arranged along the c-direction. Excess oxygen in the interstices of the rock salt layers contributes to improved ab-plane conductivity, while oxygen vacancies enhance c-axis conductivity. The high concentration of interstitial oxygen ensures rapid oxygen transport within the ceramic material, resulting in an extremely high oxygen surface exchange coefficient. Currently, research on the modification of RP-type perovskites focuses primarily on elemental doping of single-phase materials, making it difficult to achieve both enhanced catalytic activity and chemical stability.

[0004] The prior art discloses a one-pot method for synthesizing La 0.8 Sr 1.2 FeO 4+δ -xLa 0.4 Sr 0.6 FeO 3-δ, x = 10-50 mol%. The prepared Rp-perovskite composite improves the uniformity of the two-phase mixing and has high thermodynamic stability. The prepared solid oxide fuel cell has high thermal cycling stability, electrochemical stability, and high output power.

[0005] To lower fuel cell operating temperatures and reduce material manufacturing costs, higher requirements are placed on catalytic materials, requiring newer, more active materials. However, current single-phase cathode materials struggle to meet these requirements. Therefore, the combination of materials with different functionalities has become a trend in cathode material development. The heterojunction formed by these composite materials can increase the surface oxygen exchange rate and accelerate the oxygen reduction reaction. Composite materials are prepared using a variety of methods, including traditional mechanical mixing, impregnation, pulsed laser deposition (PLD), and atomic layer deposition (ALD). The impregnation method involves infiltrating a porous ceramic scaffold (support) with a liquid containing the desired components, which can increase the oxygen exchange rate at the electrode surface, thereby further enhancing the ORR reaction rate. While the impregnation method is widely used for cathode morphology control, its operation is complex and unsuitable for industrial production. ALD allows for atomic-level modification of the surface composition and morphology of materials, enabling atomic-scale control of structure, composition, doping, and nanostructure to enhance material performance, charge transfer rate, catalytic activity, and surface dynamics. However, the organometallic precursors used in ALD are typically expensive. In the actual deposition process, the low utilization rate of precursors and the manufacturing cost also limit it. Summary of the Invention

[0006] To address the shortcomings of the aforementioned background technology, the present invention provides a CO2-resistant composite cathode material for solid oxide fuel cells, its preparation method, and its application. This composite cathode material is an in-situ self-assembled composite cathode material of praseodymium oxide and an Rp-type perovskite. Its preparation is simple and easy, and the amount of the second phase material introduced can be controlled simply by varying the amount of Pr added. This dual-phase composite material synergistically improves both oxygen reduction reaction catalytic activity and CO2-resistant performance.

[0007] The first object of the present invention is to provide a composite cathode material for solid oxide fuel cells that is resistant to CO2 poisoning. The raw material composition of the composite cathode material has the general chemical formula of Pr x Sr 0.6 Co 0.5 Fe 0.5 O 3-δ , where x=1.0~1.5.

[0008] Preferably, the raw material composition chemical formula of the composite cathode material includes Pr 1.2 Sr 0.6 Co 0.5 Fe 0.5 O3-δ 、Pr 1.4 Sr 0.6 Co 0.5 Fe 0.5 O 3-δ .

[0009] A second object of the present invention is to provide a method for preparing a composite cathode material for a solid oxide fuel cell that is resistant to CO2 poisoning, comprising the following steps: According to the chemical formula of raw materials Pr x Sr 0.6 Co 0.5 Fe 0.5 O 3-δ Weigh the raw materials according to the molar ratio of each element in the mixture, and evenly disperse the raw materials in the water solvent to obtain a mixed solution; adding a complexing agent to the mixed solution to complex the metal ions in the mixed solution to obtain a gel solution; The gel solution is naturally expanded to obtain a precursor; The precursor is ground into powder and calcined to obtain a solid oxide fuel cell composite cathode material that is resistant to CO2 poisoning.

[0010] Preferably, the complexing agent comprises ethylenediaminetetraacetic acid and citric acid; The molar ratio of the ethylenediaminetetraacetic acid and citric acid to the total amount of the added metal elements is 1:2:1.

[0011] Preferably, the gel solution is prepared according to the following steps: The complexing agent is added to the mixed solution in multiple times, and the pH of the solution is adjusted to 7-8 with ammonia water to fully dissolve the ethylenediaminetetraacetic acid. The solution is then placed in a water bath at 75-85°C and stirred to complex the metal ions in the mixed solution to obtain a gel solution.

[0012] Preferably, the natural expansion process is to heat the gel solution at 200-300° C. for 2-4 hours; The calcination temperature is 950-1100° C., and the holding time is 3-6 hours.

[0013] The third object of the present invention is to provide a CO2-resistant solid oxide fuel cell composite cathode material for use in a fuel cell.

[0014] A fourth object of the present invention is to provide an electrolyte-supported symmetrical fuel cell comprising a solid oxide fuel cell composite cathode material that is resistant to CO2 poisoning.

[0015] A fifth object of the present invention is to provide a method for preparing an electrolyte-supported symmetrical fuel cell, comprising the following steps: Grind the composite cathode material into 0.3-0.8 μm powder; Add appropriate amount of terpineol to the powder, binder and pore-forming agent, mix well, and obtain cathode slurry; The cathode slurry is evenly coated on a dense electrolyte substrate and calcined at 950-1100°C for 1-3 hours to obtain an electrolyte-supported symmetrical fuel cell. Among them, the electrolyte base is La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 2.8 Electrolyte base; binder is ethyl cellulose; pore-forming agent is soluble starch.

[0016] The sixth object of the present invention is to provide an anode-supported fuel cell, comprising a cathode, a barrier layer, an electrolyte, and an anode support; the cathode comprises the above-mentioned CO2-resistant solid oxide fuel cell composite cathode material.

[0017] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a CO2-resistant solid oxide fuel cell composite cathode material and its preparation method and application. The present invention forms an Rp phase perovskite material and Pr6O4 composite cathode material by in-situ self-assembly. 11 Composite cathode material, simple process; the present invention realizes Pr6O by adjusting the amount of Pr added 11 The composite material provided by the present invention exhibits efficient oxygen reduction reaction catalytic activity and resistance to CO2 poisoning, and has high chemical stability.

[0018] The present invention can regulate the amount of the second phase material introduced by controlling the amount of Pr element added. The in-situ self-assembly composite method enhances the interfacial bonding strength between the phases and improves the structural stability of the electrode during operation. 11 It promotes the adsorption and dissociation of surface oxygen, improves the oxygen surface exchange process in the ORR process, and the Rp phase uses the interstitial replacement of the rock salt layer and the vacancy diffusion of the perovskite layer to achieve multiple oxygen transport, reducing the bulk diffusion resistance of oxygen ions. The two synergistically promote the oxygen reduction reaction process. 3+ / 4+ The higher acidity of the cations inhibits the reaction of alkaline earth metal oxides to form carbonates on the surface, showing excellent CO2 resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 In situ self-assembled Pr6O 11 @PSCF 214-327 Schematic diagram of the sample preparation process.

[0020] Figure 2 (a) is based on Pr 1.2Sr 0.6 Co 0.5 Fe 0.5 O 3-δ 、Pr 1.2 Sr 0.6 Co 0.5 Fe 0.5 O 3-δ and Pr 1.2 Sr 0.6 Co 0.5 Fe 0.5 O 3-δ PSCF obtained by calcining the raw materials at 1000℃ in air for 5 hours 214-327 、6P-PSCF 214-327 and 12P-PSCF 214-327 XRD patterns of the samples; (bd) are PSCF 214-327 (b) 6P-PSCF 214-327 (c) and 12P-PSCF 214-327 (d) XRD refinement pattern of the sample.

[0021] Figure 3 EIS spectra of symmetrical batteries based on different sample electrodes in air atmosphere: (a) PSCF 214-327 ; (b) 6P-PSCF 214-327 ; (c) 12P-PSCF 214-327 ; (d) PSCF 214 With PSCF 327 Mechanically mix the sample.

[0022] Figure 4 (a) SEM image of the cross section of the anode-supported full cell; (b) 6P-PSCF 214-327 IVP characteristic curve of a single cell with the material as cathode at 650-800 °C; (c) Comparison of IVP characteristics of full cells of different samples; (d) 6P-PSCF under constant voltage conditions at 750 °C 214-327 Current density-time relationship of a single cell with the material as cathode Figure 5 (a) Changes of ASR values ​​over time after treatment with different CO2 concentrations; (b) FT-IR spectra of samples after CO2 treatment. DETAILED DESCRIPTION

[0023] In order to enable those skilled in the art to better understand and implement the technical solution of the present invention, the present invention is further described below with reference to specific embodiments and drawings, but the embodiments are not intended to limit the present invention.

[0024] In order to lower the operating temperature of the fuel cell and reduce the manufacturing cost of the material, the present invention places higher requirements on the catalytic material and requires newer and more active materials. However, the single-phase material currently used as the cathode is difficult to meet the requirements.

[0025] The purpose of the present invention is to provide a solid oxide fuel cell composite cathode material resistant to CO2 poisoning, and its preparation method and application, mainly to address the problem that existing cathode materials containing alkaline earth metals are susceptible to CO2 poisoning.

[0026] In order to achieve the above-mentioned object, the first aspect of the present invention provides a solid oxide fuel cell composite cathode material resistant to CO2 poisoning, the raw material composition of the composite cathode material has the general chemical formula of Pr x Sr 0.6 Co 0.5 Fe 0.5 O 3-δ , where x = 1.0~1.5 and δ refers to the oxygen non-stoichiometric coefficient.

[0027] The CO2 poisoning-resistant solid oxide fuel cell composite cathode material provided by the present invention has high-efficiency oxygen reduction catalytic activity and CO2 poisoning resistance.

[0028] The raw material composition chemical formula of the composite cathode material includes Pr 1.2 Sr 0.6 Co 0.5 Fe 0.5 O 3-δ 、Pr 1.4 Sr 0.6 Co 0.5 Fe 0.5 O 3-δ .

[0029] A second aspect of the present invention provides a method for preparing a composite cathode material for a solid oxide fuel cell that is resistant to CO2 poisoning, comprising the following steps: According to the chemical formula of raw materials Pr x Sr 0.6 Co 0.5 Fe 0.5 O 3-δ Weigh the raw materials according to the molar ratio of each element in the mixture, and evenly disperse the raw materials in the water solvent to obtain a mixed solution; adding a complexing agent to the mixed solution to complex the metal ions in the mixed solution to obtain a gel solution; The gel solution is naturally expanded to obtain a precursor; The precursor is ground into powder and calcined to obtain a solid oxide fuel cell composite cathode material that is resistant to CO2 poisoning.

[0030] The present invention uses the sol-gel method to prepare a two-phase composite material - Rp phase (Pr z Sr 1-z ) n+1 (Co y Fe 1-y ) n O 3n+1 (n = 1,2; abbreviated as PSCF 214-327 ) and Pr6O 11 The preparation process of this application is simple, and the amount of the second phase material introduced can be controlled by simply changing the amount of Pr element added. The in-situ self-assembly composite method enhances the interfacial bonding strength between the phases and improves the structural stability of the electrode during operation. 11 To promote the adsorption and dissociation of surface oxygen, the Rp phase uses the interstitial replacement of the rock salt layer and the vacancy diffusion of the perovskite layer to achieve multiple oxygen transport, and the two synergistically promote the oxygen reduction reaction process. 3+ / 4+ The higher acidity of the cations inhibits the reaction of alkaline earth metal oxides to form carbonates on the surface, showing excellent CO2 resistance.

[0031] Wherein, the complexing agent includes ethylenediaminetetraacetic acid and citric acid; The molar ratio of the ethylenediaminetetraacetic acid and citric acid to the total amount of the added metal elements is 1:2:1.

[0032] The gel solution was prepared according to the following steps: The complexing agent is added to the mixed solution in multiple times, and the pH of the solution is adjusted to 7-8 with ammonia water to fully dissolve the EDTA. The solution is then placed in a water bath at 75-85°C and stirred to complex the metal ions in the mixed solution to obtain a gel solution.

[0033] The natural expansion process is to heat the gel solution at 200~300℃ for 2~4 hours; The calcination temperature is 950-1100°C, and the holding time is 3-6 hours.

[0034] Exemplarily, a method for preparing a CO2-resistant solid oxide fuel cell composite cathode material comprises: According to the chemical formula Pr x Sr 0.6 Co 0.5 Fe 0.5 O 3-δThe masses of Pr(NO₃)₃·6H₂O, Co(NO₃)₂·6H₂O, Sr(NO₃)₂, and Fe(NO₃)₃·9H₂O were calculated based on the stoichiometric ratios in the solution. The reagents were weighed and placed in a beaker. An appropriate amount of ultrapure water was added and magnetic stirring was applied until completely dissolved. Citric acid and ethylenediaminetetraacetic acid (EDTA) were added as complexing agents, in small increments, to the clear solution. Since EDTA is insoluble in acidic conditions, the pH of the solution was adjusted with ammonia until the EDTA was completely dissolved, resulting in a clear purple-black solution. The beaker was placed in an 80°C constant-temperature water bath with moderate stirring to ensure complete complexation of the metal ions. The water evaporated, resulting in a viscous purple-black gel. The beaker was then placed in an oven, heated to 250°C, and maintained at this temperature for 3 hours to allow the gel to spontaneously ignite and expand, yielding a fluffy black precursor. The precursor was ground into powder in an agate mortar, placed in a crucible, and calcined in a high-temperature muffle furnace. The temperature was programmed to be kept at 1000 °C for 5 h to remove organic matter and nitrate particles in the precursor, and the in-situ self-assembled (Pr z Sr 1-z ) n+1 (Co 0.5 Fe 0.5 ) n O 3n+1 (n = 1,2) 11 (denoted as xPO-PSCF 214-327 ) composite materials, z = 0 ~ 1; the specific process is as follows Figure 1 The powder is then placed in a ball mill and wet-milled with an appropriate amount of ethanol to refine the particle size.

[0035] It should be noted that the obtained (Pr z Sr 1-z ) n+1 (Co 0.5 Fe 0.5 ) n O 3n+1 n = 1 in the PSCF 214 and n = 2 is PSCF 327 Two types of R P A composite material of phases; z represents the stoichiometric number of the element, z=0~1.

[0036] A third aspect of the present invention provides an application of a CO2-poisoning-resistant solid oxide fuel cell composite cathode material in a fuel cell.

[0037] A fourth aspect of the present invention provides an electrolyte-supported symmetrical fuel cell comprising a solid oxide fuel cell composite cathode material that is resistant to CO2 poisoning.

[0038] A fifth aspect of the present invention provides a method for preparing an electrolyte-supported symmetrical fuel cell, comprising the following steps: Grind the composite cathode material into 0.3-0.8 μm powder; Add appropriate amount of terpineol to the powder, binder and pore-forming agent, mix well, and obtain cathode slurry; The cathode slurry is evenly coated on a dense electrolyte substrate and calcined at 950-1100°C for 1-3 hours to obtain an electrolyte-supported symmetrical fuel cell. Among them, the electrolyte base is La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 2.8 Electrolyte base; binder is ethyl cellulose; pore-forming agent is soluble starch.

[0039] Exemplarily, a symmetrical battery is prepared using the composite cathode material provided by the present invention, and the impedance test is performed using an electrolyte-supported symmetrical battery, wherein the electrolyte support is prepared by a dry pressing method.

[0040] Electrolyte sheet preparation: First, 10 g of LSGM was added to a 5% polyvinyl alcohol (PVA) solution as a binder, with a 2:1 ratio of LSGM to PVA. The two were thoroughly mixed by grinding until the mixture became a dry, fine powder. 0.3–0.35 g of the powder was weighed and poured into a tablet press. The press was maintained at a pressure of 10 MPa for 10 minutes, followed by a pressure of 20 MPa for 10 minutes, until it was compacted into a 15 mm diameter green sheet. The sheet was then spread flat on a setter plate and placed in a high-temperature calcining furnace. The temperature was programmed to 1450°C and held for 8 hours to produce a dense, black electrolyte.

[0041] The preparation method of an electrolyte-supported symmetrical battery includes: polishing the electrolyte sheet on sandpaper to a thickness of about 0.3 mm, and applying the electrode slurry to the electrolyte by screen printing technology. Specifically, it includes: weighing 0.1 g of composite cathode material powder, 8 mg of binder ethyl cellulose, 12 mg of pore-forming agent soluble starch, adding an appropriate amount of pine oil and mixing them evenly in a mortar. Use a 200-mesh screen to evenly coat the slurry on the electrolyte substrate. After calcining at 1000 ° C in a muffle furnace, silver is used as the current collector for performance testing. Silver paste is used to bond the silver wire to the electrode, and the heat is kept at 750 ° C for 30 minutes to remove organic matter and enhance the conductive properties of the current collector.

[0042] A sixth aspect of the present invention provides an anode-supported fuel cell comprising a cathode, a barrier layer, an electrolyte, and an anode support; the cathode comprises a solid oxide fuel cell composite cathode material that is resistant to CO2 poisoning.

[0043] The solid oxide fuel cell is an anode-supported full cell, including a cathode, a barrier layer, an electrolyte, and an anode support. The cathode component is made by preparing a cathode slurry with a mass ratio of 100:40:8:12 including a composite cathode material: a dispersant: a binder: a pore-forming agent. The cathode slurry is then screen-printed on the surface of the electrolyte layer on the cathode side, dried, and sintered at 1000°C for 2 hours. The dispersant is pineol, the binder is ethyl cellulose, and the pore-forming agent is soluble starch. The material of the electrolyte layer is YSZ, and the corresponding molecular formula is (ZrO2). 0.92 (Y2O3) 0.08 .

[0044] The discharge test used an anode-supported full cell. The anode was a nickel oxide and YSZ composite anode (Ni:YSZ = 60:40 wt.%). Soluble starch was used as a pore-forming agent. The anode support was prepared by dry pressing and pre-fired at 800°C in a muffle furnace for 2 hours. A YSZ electrolyte slurry was then sprayed onto one side of the anode blank and calcined at 1400°C for 5 hours to densify the electrolyte. To prevent reaction between the cathode and electrolyte, GDC was used as a barrier layer to separate the electrode from the electrolyte. The barrier layer was calcined at 1300°C for 3 hours.

[0045] It should be noted that the experimental methods used in the present invention are all conventional methods unless otherwise specified; the reagents and materials used are all commercially available unless otherwise specified.

[0046] Example 1 Preparation of 0.01 mol composite electrode material (Pr z Sr 1-z ) n+1 (Co 0.5 Fe 0.5 ) n O 3n+1 (n=1,2)&6%Pr6O 11 .

[0047] According to the general formula Pr 1.2 Sr 0.6 Co 0.5 Fe 0.5 O 3-δ5.22 g Pr(NO3)3•6H2O, 1.46 g Co(NO3)2•6H2O, 1.27 g Sr(NO3)2, and 2.02 g Fe(NO3)3·9H2O were weighed as metal precursors and dissolved in 500 ml of deionized water according to the stoichiometric ratio. After dissolution, a purple-black clear solution was obtained. Citric acid and ethylenediaminetetraacetic acid (EDTA) were used as complexing agents. 5.70 g EDTA and 7.49 g citric acid were added respectively. Ammonia water was added dropwise until the solution pH was ≈ 7~8. The mixture was stirred until the EDTA was completely dissolved. The clear solution was then dried in an 80°C water bath until it became a gel. The gel was transferred to a 250°C constant temperature oven and allowed to spontaneously combust to obtain a black-gray precursor powder. The precursor was then ground into a fine powder in a mortar and placed in a muffle furnace. The temperature was raised to 1000°C and kept at this temperature for 5 hours to obtain (Pr z Sr 1-z ) n+1 (Co 0.5 Fe 0.5 ) n O 3n+1 (n=1,2)&6%Pr6O 11 (denoted as 6P-PSCF 214-327 ).

[0048] Example 2 The preparation of Example 2 is basically the same as that of Example 1, except that the general formula used in the preparation of the composite material in Example 2 is Pr 1.4 Sr 0.6 Co 0.5 Fe 0.5 O 3-δ The obtained dual-phase composite material is (Pr z Sr 1-z ) n+1 (Co 0.5 Fe 0.5 ) n O 3n+1 (n= 1,2)12%Pr6O 11 (denoted as 12P-PSCF 214-327 ).

[0049] Comparative Example The preparation of this comparative example is the same as that of Example 1, except that the general formula used in the preparation of the material in this comparative example is Pr 1.0 Sr 0.6 Co 0.5 Fe 0.5 O 3-δ The obtained material is (Pr z Sr 1-z ) n+1 (Co 0.5 Fe0.5 ) n O 3n+1 (n = 1, 2, denoted as PSCF 214-327 ).

[0050] In order to illustrate the relevant properties of the composite cathode material provided by the present invention, it is described in conjunction with the accompanying drawings.

[0051] The electrode materials prepared in Examples 1 and 2 and the comparative example were subjected to XRD testing and data refinement analysis. The results are as follows: Figure 2 shown. Figure 2 (a) plots the PSCF 214-327 、6P-PSCF 214-327 and 12P-PSCF 214-327 In order to further explore the crystal structure of the composite material, the XRD data was finely fitted by Rietveld refinement. Figure 2 (b), (c), and (d) are the refined curves of the composite material after fitting. Rp and Rwp are both within 15%, and the fitting results are reliable. 214-327 For n = 1 (PSCF 214 ) and n = 2(PSCF 327 ) P Phase composite material, 6P-PSCF 214-327 and 12P-PSCF 214-327 PSCF 214 、PSCF 327 and Pr6O 11 Three-phase composite materials. During the synthesis of composite materials, increasing the stoichiometric ratio of Pr elements can increase the Pr6O 11 The content of Pr is not only the formation of Pr6O 11 In order to ensure the structural stability of the composite material, the content of each phase will be self-regulated during phase formation, and the excess Pr element is more inclined to form PSCF 214 , to achieve the most stable state, which is one of the advantages of in situ self-assembly.

[0052] The electrode materials prepared in Examples 1 and 2 and the comparative example were respectively made into symmetrical batteries, and electrochemical impedance spectroscopy (EIS) tests were performed on them. Figure 3 (a–c) show the PSCF 214-327 、6P-PSCF 214-327 and 12P-PSCF 214-327Impedance spectra of three cathodes at 650-800 °C. It can be seen that with increasing temperature, the polarization resistance of all composite cathodes decreases significantly, indicating that high temperature helps to accelerate the ORR reaction kinetics. In addition, to evaluate the effect of in situ self-assembled heterostructures on the cathode polarization resistance, pure phase PSCF 214 and PSCF 327 The composite cathode prepared by mechanical mixing in equal proportions was tested for comparison, and its impedance spectrum is shown in Figure 2. Figure 3 As shown in (d). The results show that the PSCF obtained by mechanical mixing 214-327 The ASR of the cathode under the same conditions was 1.01 Ω cm 2 , while PSCF obtained by in situ self-assembly 214-327 The cathode ASR is only 0.77 Ω cm 2 It can be seen that compared with simple physical mixing, the in-situ constructed ABO 214 –ABO 327 The heterogeneous structure significantly reduces the cathode's polarization resistance and enhances ORR activity. This performance improvement is attributed to the tighter in-situ interphase bonding and stronger interphase synergy, which facilitates the transport of oxygen ions and the surface exchange of oxygen molecules, ultimately accelerating the cathode ORR kinetics.

[0053] The electrode materials prepared in Examples 1, 2 and the comparative example were made into full batteries, and the cathode side of the battery was sealed on the inside of the alumina ceramic tube with ceramic glue (Ceramabond552, AREMCO). After it was naturally dried and hardened, the operation was repeated many times to ensure good sealing of the battery for subsequent testing. The packaged battery was placed in a vertical furnace and heated. Humidified H2 (containing 3% H2O) and ambient air were used as fuel and oxidant, and tested at 800 ° C. In the experiment, the voltage change of the American Arbin fuel cell test system under given external current conditions was used, and finally the current-voltage-power density was plotted. (IVP )curve.

[0054] Figure 4 (a) shows a cross-sectional SEM image of the full cell. It is clearly visible that the 10 μm-thick YSZ electrolyte layer is densely structured, while the 2 μm-thick GDC barrier layer is evenly distributed between the electrolyte layer and the cathode layer. The porous structure of the cathode layer also facilitates the diffusion and reaction of oxygen molecules, improving the kinetics of the oxygen reduction reaction. Figure 4 Middle (bc) shows the 6P-PSCF 214-327 IVP curves at different temperatures and performance comparison of different cathode materials at 800 ℃. The experimental results show that 6P-PSCF 214-327The peak power densities (Pmax) of the cathode at 800, 750, 700, and 650 °C are 1.51, 1.09, 0.96, and 0.72 W·cm, respectively. -2 Among them, 6P-PSCF at 800 ℃ 214-327 The cathode Pmax is much higher than PSCF 214-327 0.92 mW cm for the cathode cell -2 The long-term operating stability of fuel cells is an important factor affecting their practical applications. Figure 4 As shown in (d), when the current is 0.7 V, the 6P-PSCF 214-327 The SOFC with praseodymium oxide as cathode was stably tested at 750 °C for nearly 200 hours and maintained a very stable working state, indicating that the in situ self-assembled praseodymium oxide and RP phase heterostructure material has good chemical stability and sustained oxygen reduction reaction catalytic activity.

[0055] The symmetrical battery of Example 1 was made and subjected to EIS test at 650°C in a high concentration CO2 atmosphere to verify the tolerance of the composite electrode to CO2 poisoning. The powder after CO2 treatment was also subjected to infrared test. Figure 5 As shown in (a), as the stable time goes by, the PSCF 214-327 The ASR growth rate of 6P-PSCF is significantly higher than that of 6P-PSCF 214-327 , indicating that the latter has better impedance stability under the action of CO2. This performance advantage may be related to the Sr content distribution shown by XPS results. 214-327 The surface Sr content is high, which is more likely to react with CO2 to form carbonates, thereby exacerbating the poisoning effect. 214-327 The praseodymium oxide phase at the cathode effectively hinders Sr segregation, and due to its higher surface acidity, it further reduces the tendency to form SrCO3, making it exhibit stronger CO2 tolerance. Figure 5 (b) shows the Fourier transform infrared (FT-IR) spectrum of the cathode material after CO2 treatment. 214-113 At 864.22 and 1448.78 cm −1 There is an obvious carbonate characteristic peak at 6P-PSCF. 214-113 These characteristic peaks were not observed in the FT-IR spectrum of 6P-PSCF. 214-113 It has excellent resistance to CO2 poisoning.

[0056] In summary, the present invention provides a two-phase composite cathode material for medium- and low-temperature solid oxide fuel cells, which has high oxygen reduction catalytic activity and resistance to CO2 poisoning. The two-phase composite material, Rp phase (Pr z Sr1-z ) n+1 (Co 0.5 Fe 0.5 ) n O 3n+1 (n = 1,2; abbreviated as PSCF 214-327 ) and Pr6O 11 The preparation process of the present invention is simple, and the amount of the second phase material introduced can be controlled by simply changing the amount of Pr element added. The in-situ self-assembly composite method enhances the interfacial bonding strength between the phases and improves the structural stability of the electrode during operation. 11 To promote the adsorption and dissociation of surface oxygen, the Rp phase uses the interstitial replacement of the rock salt layer and the vacancy diffusion of the perovskite layer to achieve multiple oxygen transport, and the two synergistically promote the oxygen reduction reaction process. 3+ / 4+ The higher acidity of the cations inhibits the reaction of alkaline earth metal oxides to form carbonates on the surface, showing excellent CO2 resistance.

[0057] The present invention describes preferred embodiments and their effects. However, those skilled in the art, once informed of the basic inventive concept, may make additional changes and modifications to these embodiments. Therefore, it is intended that the appended claims be interpreted to include the preferred embodiments as well as all changes and modifications that fall within the scope of the invention.

[0058] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A solid oxide fuel cell composite cathode material resistant to CO2 poisoning, characterized in that: The chemical formula of the raw material composition of the composite cathode material is Pr x Sr 0.6 Co 0.5 Fe 0.5 O 3-δ , where x=1.0~1.

5.

2. The CO2-poisoning-resistant solid oxide fuel cell composite cathode material according to claim 1, characterized in that: The raw material composition chemical formula of the composite cathode material includes Pr 1.2 Sr 0.6 Co 0.5 Fe 0.5 O 3-δ 、Pr 1.4 Sr 0.6 Co 0.5 Fe 0.5 O 3-δ .

3. A method for preparing a CO2-resistant solid oxide fuel cell composite cathode material according to claim 1 or 2, characterized in that: The following steps are involved: According to the chemical formula of raw materials Pr x Sr 0.6 Co 0.5 Fe 0.5 O 3-δ Weigh the raw materials according to the molar ratio of each element in the mixture, and evenly disperse the raw materials in the water solvent to obtain a mixed solution; adding a complexing agent to the mixed solution to complex the metal ions in the mixed solution to obtain a gel solution; The gel solution is naturally expanded to obtain a precursor; The precursor is ground into powder and calcined to obtain a solid oxide fuel cell composite cathode material that is resistant to CO2 poisoning.

4. The method for preparing a CO2-resistant solid oxide fuel cell composite cathode material according to claim 3, characterized in that: The complexing agent includes ethylenediaminetetraacetic acid and citric acid; The molar ratio of the ethylenediaminetetraacetic acid and citric acid to the total amount of the added metal elements is 1:2:

1.

5. The method for preparing a CO2-resistant solid oxide fuel cell composite cathode material according to claim 4, characterized in that: The gel solution was prepared according to the following steps: The complexing agent is added to the mixed solution in multiple times, and the pH of the solution is adjusted to 7-8 with ammonia water to fully dissolve the ethylenediaminetetraacetic acid. The solution is then placed in a water bath at 75-85°C and stirred to complex the metal ions in the mixed solution to obtain a gel solution.

6. The method for preparing a CO2-resistant solid oxide fuel cell composite cathode material according to claim 3, characterized in that: The natural expansion process is to heat the gel solution at 200~300℃ for 2~4h; The calcination temperature is 950-1100° C., and the holding time is 3-6 hours.

7. Use of the CO2 poisoning resistant solid oxide fuel cell composite cathode material according to claim 1 or 2 in a fuel cell.

8. An electrolyte-supported symmetrical fuel cell, characterized in that: The solid oxide fuel cell composite cathode material comprising the CO2 poisoning-resistant material according to claim 1 or 2.

9. A method for preparing an electrolyte-supported symmetrical fuel cell according to claim 8, characterized in that: The following steps are involved: Grind the composite cathode material into 0.3-0.8 μm powder; Add appropriate amount of terpineol to the powder, binder and pore-forming agent, mix well, and obtain cathode slurry; The cathode slurry is evenly coated on a dense electrolyte substrate and calcined at 950-1100°C for 1-3 hours to obtain an electrolyte-supported symmetrical fuel cell. Among them, the electrolyte base is La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 2.8 Electrolyte base; binder is ethyl cellulose; pore-forming agent is soluble starch.

10. An anode-supported fuel cell, characterized in that: The invention comprises a cathode, a barrier layer, an electrolyte, and an anode support; the cathode comprises the CO2-poisoning-resistant solid oxide fuel cell composite cathode material according to claim 1 or 2.

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