Reversible solid oxide battery composite oxygen electrode and preparation method and application thereof

Abstract

The invention relates to a reversible solid oxide battery composite oxygen electrode and a preparation method and application thereof, and the preparation method comprises the following steps: weighing soluble salt containing praseodymium, nickel and cobalt according to the stoichiometric ratio of PNCO, and dissolving the soluble salt in water to obtain a mixed solution; adding a complexing agent into the mixed solution, and stirring after ultrasonic treatment to obtain a PNCO precursor solution; transferring the PNCO precursor solution to the surface of an LSC oxygen electrode for vacuum impregnation; and calcining the impregnated battery in a sintering furnace, and repeating impregnation and calcination cycles to obtain the PNCO-LSC composite oxygen electrode. According to the invention, the PNCO material with high oxygen ion conductivity is loaded on the surface of the LSC oxygen electrode with high electron conductivity through a solution impregnation method, so that the charge transfer capability and oxygen ion transfer rate of the oxygen electrode are remarkably improved, reaction active sites are increased, and the oxygen electrode has more excellent electrolytic current density in a CO2 electrolysis mode, and can be applied to the field of CO2 electrolysis. And the good stability of the battery in the long-term operation process is ensured.

Description

Technical Field

[0001] This invention relates to the field of electrochemical reduction of carbon dioxide and reversible solid oxide batteries, and more specifically to a reversible solid oxide battery composite oxygen electrode, its preparation method, and its application. Background Technology

[0002] With the continuous and rapid growth of global fossil energy consumption, a large amount of carbon dioxide (CO2) is emitted into the atmosphere, triggering an increasingly severe greenhouse effect and having a significant impact on the global climate and environment. How to efficiently control CO2 emissions and mitigate global warming has become an important issue that urgently needs to be addressed globally, and has also attracted widespread attention from many researchers.

[0003] Solid oxide electrolyzers (SOECs), as clean and efficient energy conversion devices, can effectively reduce CO2 to carbon monoxide (CO) under high-temperature conditions, providing an ideal pathway for the resource utilization of CO2. During the operation of a high-temperature SOEC CO2 electrolysis system, CO2 undergoes an electrochemical reduction reaction at the cathode to generate CO. Oxygen ions generated during the reaction are conducted to the anode (oxygen electrode) through oxygen vacancies in the electrolyte, where an electrochemical oxidation reaction (oxygen evolution reaction, OER) occurs on the surface of the oxygen electrode. The oxygen ions lose electrons to generate oxygen gas (O2). From the reaction mechanism perspective, the cathode reaction of CO2 electrolysis involves only the transfer of two electrons, while the oxygen evolution reaction at the anode requires the transfer of four electrons. This reaction characteristic means that the energy consumption of high-temperature SOEC CO2 electrolysis is mainly concentrated in the anodic polarization process. Therefore, developing advanced oxygen electrode materials is key to improving the efficiency of CO2 electrolysis.

[0004] An ideal oxygen electrode material must simultaneously possess the following core properties: high ionic and electronic conductivity, excellent stability in oxidizing atmospheres, and good catalytic activity for OER. Currently, perovskite oxide materials are the most commonly used oxygen electrode (anodide) materials in the SOEC field, with typical examples including La. 1-x Sr x MnO 3±δ (LSM), La 1-x Sr x Co 1-y Fe y O 3-δ (LSCF) and PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.5 O 5+δ(PBSCF), etc. However, these traditional perovskite oxide materials generally suffer from insufficient catalytic activity in the oxygen evolution reaction (OER), resulting in significant anodic polarization loss during SOEC electrolysis of CO2 and energy conversion efficiency that is difficult to meet the needs of practical applications. At the same time, their long-term working stability also needs to be further improved. This has become the main technical bottleneck restricting the large-scale application of SOEC technology in CO2 resource utilization. Summary of the Invention

[0005] To address the core problems of insufficient catalytic activity and large polarization loss in existing perovskite oxide oxygen electrode materials, this invention aims to provide a reversible solid oxide battery composite oxygen electrode, its preparation method, and its application.

[0006] The preparation method of the reversible solid oxide battery composite oxygen electrode according to the present invention includes the following steps: S1, according to the stoichiometric ratio of PNCO, a soluble salt containing praseodymium, nickel and cobalt is weighed and dissolved in water to obtain a mixed solution; S2, a complexing agent is added to the mixed solution, and after ultrasonic treatment and stirring, a PNCO precursor solution is obtained; S3, the PNCO precursor solution is transferred to the surface of the LSC oxygen electrode for vacuum impregnation; S4, the impregnated battery is placed in a sintering furnace for calcination, and the impregnation and calcination cycle of steps S3 and S4 is repeated to obtain the PNCO-LSC composite oxygen electrode.

[0007] In a preferred embodiment, in step S1, the praseodymium-containing soluble salt is praseodymium nitrate hexahydrate, the nickel-containing soluble salt is nickel nitrate hexahydrate, and the cobalt-containing soluble salt is cobalt nitrate hexahydrate; the molar fraction of praseodymium nitrate hexahydrate, nickel nitrate hexahydrate, and cobalt nitrate hexahydrate is 5%-90%.

[0008] In a preferred embodiment, in step S2, the complexing agent is selected from at least one of citric acid, ethylenediaminetetraacetic acid, polyvinylpyrrolidone, hexadecyltrimethylammonium bromide, and sodium succinate; the molar ratio of the complexing agent to PNCO is 0.6:1-1.2:1, and the concentration of the PNCO precursor solution is 0.001-0.1 mol·L⁻¹. -1 .

[0009] In a preferred embodiment, in step S3, the LSC oxygen electrode is derived from a Ni-YSZ|YSZ|GDC|LSC cell, where YSZ is yttrium-doped zirconium oxide and GDC is gadolinium-doped cerium oxide.

[0010] In a preferred embodiment, in step S3, the volume of the PNCO precursor liquid used for each impregnation is 5-100 μL, and the effective impregnation area of ​​the battery LSC oxygen electrode is 4 cm × 4 cm - 6 cm × 6 cm.

[0011] In a preferred embodiment, in step S4, the calcination process is as follows: the temperature is increased to 300-600℃ at a programmed heating rate of 1℃ / min-5℃ / min, and held for 0.1-5h; then the temperature is increased to 900-1100℃ at a programmed heating rate of 1-5℃ / min, and sintered for 0.1-5h.

[0012] In a preferred embodiment, in step S4, the number of impregnation and calcination cycles is 2-6.

[0013] The reversible solid oxide battery composite oxygen electrode according to the present invention is prepared according to the above-described preparation method and includes an LSC substrate layer and a PNCO active layer coated on the surface of the LSC substrate layer.

[0014] The application of the reversible solid oxide battery composite oxygen electrode according to the present invention covers both solid oxide fuel cell mode and solid oxide electrolyzer mode.

[0015] In a preferred embodiment, the application includes the use of electrolytic carbon dioxide for resource utilization.

[0016] This invention utilizes a solution impregnation method to load a PNCO material with high oxygen ion conductivity onto the surface of a LSC oxygen electrode with high electronic conductivity, forming a PNCO-LSC composite oxygen electrode. This effectively solves the technical problems of concentrated polarization loss of the oxygen electrode and insufficient OER catalytic activity of traditional perovskite oxygen electrodes in SOEC CO2 electrolysis systems. It significantly improves the charge transport capacity and oxygen ion transport rate of the oxygen electrode, increases the number of reactive sites, and enables reversible solid oxide batteries to exhibit higher peak power density in fuel cell mode and superior electrolysis current density in CO2 electrolysis mode. Compared with unmodified LSC oxygen electrode batteries, the performance is greatly improved, and the battery can maintain good stability during long-term operation, providing efficient and reliable technical support for CO2 resource utilization. Attached Figure Description

[0017] Figure 1 It is the bare LSC battery and PNCO according to the present invention. 1 -LSC battery, PNCO 2 -LSC batteries and PNCO 3 -Microscopic morphology of the oxygen electrode surface of an LSC cell.

[0018] Figure 2 The data is the current density-voltage-power density (IVP) curve of the bare LSC cell according to the present invention in solid oxide fuel cell (SOFC) mode.

[0019] Figure 3 It is the PNCO according to the present invention 2- IVP curve of LSC battery in SOFC mode.

[0020] Figure 4 The bare LSC battery and PNCO according to the present invention 2 Electrochemical impedance spectroscopy of the -LSC cell obtained by testing in SOFC mode, open circuit voltage, and at 800 °C.

[0021] Figure 5 It is the bare LSC battery and PNCO according to the present invention. 1 -LSC battery, PNCO 2 -LSC batteries and PNCO 3 - Current density-voltage (IV) curve of LSC cell for CO2 electrolysis in solid oxide electrolyzer (SOEC) mode.

[0022] Figure 6 It is the bare LSC battery and PNCO according to the present invention. 1 -LSC battery, PNCO 2 -LSC batteries and PNCO 3 Electrochemical impedance spectroscopy of the -LSC cell obtained by testing in SOEC mode, open circuit voltage, and at 800 °C.

[0023] Figure 7 It is the PNCO according to the present invention 2 -Long-term stability test curve of LSC battery in SOEC mode for CO2 electrolysis under constant current. Detailed Implementation

[0024] This invention aims to address the technical challenge of polarization loss being primarily concentrated in the oxygen electrode during SOEC CO2 electrolysis. By optimizing the structure and composition of the oxygen electrode, this invention improves its charge transport capacity, increases reactive sites, and enhances the oxygen ion transport rate, thereby strengthening the overall performance of SOEC CO2 electrolysis.

[0025] Solution impregnation is a mature material modification technology that can stably fix catalytic particles with high specific surface area onto the surface of ceramic support materials.

[0026] Ruddlesden-Popper (RP) type materials have gradually become a research hotspot due to their unique structure and excellent performance. Among them, Ln2NiO4 (Ln=La, Nd, Pr) is the most widely used oxygen electrode candidate material in this type. The structure of this type of material can be regarded as being composed of alternating LnNiO3 perovskite layers and LnO rock salt layers. This special layered structure gives it both the high electronic conductivity of perovskite materials and the high oxygen ion conductivity brought by the large amount of interstitial oxygen in the LnO rock salt layers, making it an excellent ion-electron hybrid conductor material.

[0027] This invention uses perovskite oxide material as the main body of the oxygen electrode in a battery. An RP-type material is impregnated onto the framework surface of the oxygen electrode using a solution impregnation method to construct a composite oxygen electrode. The perovskite oxide material is an LSC material with high electronic conductivity, and the RP-type material is a PNCO material with high oxygen ion conductivity, resulting in a PNCO-LSC composite oxygen electrode. While LSC materials, as the main body material of the battery oxygen electrode, exhibit excellent electron transport performance, their oxygen evolution reaction activity is insufficient. PNCO materials, on the other hand, possess high oxygen ion conductivity. This invention combines the advantages of LSC and PNCO materials, using LSC and PNCO as the substrate layer and surface active coating layer, respectively, to form a PNCO-LSC composite oxygen electrode, which can significantly improve the electrochemical performance and long-term stability of reversible solid oxide batteries. The LSC material is La... 0.6 Sr 0.4 CoO 3-δ PNCO is Pr2Ni 0.8 Co 0.2 O 4+δ (Belongs to RP type materials). It should be understood that La here... 0.6 Sr 0.4 CoO 3-δ In Pr2Ni, δ represents the oxygen defect concentration, with a typical value range of 0.1~0.25. 0.8 Co 0.2 O 4+δ In this context, δ represents the interstitial oxygen concentration, typically ranging from 0.05 to 0.3. The specific value of δ is determined by the material preparation process (such as sintering temperature and atmosphere) and the usage environment, and does not affect the implementation of the technical solution of this invention.

[0028] This invention combines the modification advantages of solution impregnation with the excellent conductivity of RP-type materials, addressing the technical shortcomings of insufficient catalytic activity in traditional perovskite oxide oxygen electrode materials. It provides a PNCO-LSC composite oxygen electrode, specifically a Ni-YSZ|YSZ|GDC|PNCO-LSC composite oxygen electrode battery. The base cell uses a commercially available Ni-YSZ|YSZ|GDC|LSC battery; where YSZ is yttrium-doped zirconium oxide (Y2O3-doped ZrO2), and GDC is gadolinium-doped cerium oxide (Gd-doped CeO2).

[0029] This invention first involves weighing praseodymium salt, nickel salt, and cobalt salt according to the stoichiometric ratio of PNCO and dissolving them in water to obtain a mixed solution. In a preferred embodiment, the praseodymium salt is praseodymium nitrate, such as Pr(NO3)3·6H2O; the nickel salt is nickel nitrate, such as Ni(NO3)2·6H2O; and the cobalt salt is cobalt nitrate, such as Co(NO3)2·6H2O. In a preferred embodiment, the molar fractions of praseodymium ions, nickel ions, and cobalt ions are 5%-90%. In one preferred embodiment, the molar fractions of praseodymium ions, nickel ions, and cobalt ions are 65.6%, 26.6%, and 7.9%, respectively.

[0030] The present invention further includes adding a complexing agent to the above-mentioned mixed solution and ultrasonically stirring to obtain a PNCO precursor solution. In a preferred embodiment, the complexing agent may be selected from at least one of citric acid (CA), ethylenediaminetetraacetic acid (EDTA), polyvinylpyrrolidone (PVP), hexadecyltrimethylammonium bromide (CTAB), and sodium succinate (AOT). In a preferred embodiment, the concentration of the PNCO precursor solution is 0.001-0.1 mol·L⁻¹. -1 In a preferred embodiment, the concentration of the PNCO precursor solution is 0.05 mol·L⁻¹. -1 In a preferred embodiment, the molar ratio of the complexing agent to PNCO is 0.6:1 to 1.2:1. In one preferred embodiment, the molar ratio of the complexing agent to PNCO is 0.747:1.

[0031] The present invention further includes using a vacuum impregnation method to transfer the PNCO precursor solution to the surface of the LSC oxygen electrode for vacuum impregnation. In a preferred embodiment, the volume of the PNCO precursor solution used for each impregnation is 5-100 μL, and the effective impregnation area of ​​the battery LSC oxygen electrode is 4 cm × 4 cm to 6 cm × 6 cm. In another preferred embodiment, the volume of the PNCO precursor solution used for each impregnation is 25 μL, and the effective impregnation area of ​​the battery LSC oxygen electrode is 5 cm × 5 cm.

[0032] The present invention further includes calcining the impregnated battery, repeating the above impregnation and calcination steps 2-6 times to obtain a PNCO-LSC composite oxygen electrode. In a preferred embodiment, the calcination process is as follows: heating to 300-600°C at a programmed temperature rise rate of 1°C / min-5°C / min, holding at that temperature for 0.1-5 hours; then heating to 900-1100°C at a programmed temperature rise rate of 1-5°C / min, and sintering for 0.1-5 hours. In a preferred embodiment, heating to 400°C at a programmed temperature rise rate of 2°C / min, holding at that temperature for 0.5 hours; then heating to 1000°C at a programmed temperature rise rate of 5°C / min, and sintering for 2 hours. It should be understood that the permeation load of the PNCO-LSC composite oxygen electrode can be changed by the number of impregnation and calcination cycles, that is, the amount of PNCO material loaded on the surface of the LSC oxygen electrode (i.e., the mass or number of moles of PNCO attached to a unit area of ​​the LSC electrode), the magnitude of which is determined by the number of impregnation and calcination cycles.

[0033] The reversible solid oxide battery composite oxygen electrode according to the present invention, prepared by the above-described method, comprises an LSC substrate and a PNCO active layer coated on the surface of the LSC substrate. In a preferred embodiment, the thickness of the PNCO active layer is 50-500 nm, and the loading is 0.1-10 mg / cm³. 2 The particle size of PNCO particles is 10~100nm.

[0034] The application of the reversible solid oxide battery composite oxygen electrode according to the present invention covers both solid oxide fuel cell and solid oxide electrolyzer modes. In a preferred embodiment, it is applied to a reversible solid oxide battery under conditions of 700~850°C and 0.1~0.3MPa.

[0035] In a preferred embodiment, the application includes the utilization of carbon dioxide through electrolysis. In a preferred embodiment, the application involves electrolyzing carbon dioxide under conditions of 10%–100% CO2 volume fraction and 5%–20% H2 volume fraction introduced onto the hydrogen electrode side.

[0036] Therefore, the reversible solid oxide battery composite oxygen electrode obtained by this invention achieves a peak power density of 0.995 W·cm³ in the PNCO-LSC battery at 800°C in solid oxide fuel cell mode. -2 In solid oxide electrolysis mode, at a temperature of 800℃ and a voltage of 1.5V, the PNCO-LSC battery achieved a current density of 0.917 A·cm⁻¹ for carbon dioxide electrolysis. -2Compared to bare LSC cells, the current density is increased by about 40%. In the 100h long-term stability test, the cell did not show significant degradation and maintained good stability. Thus, the high oxygen ion conductivity and high OER catalytic activity of PNCO complement the high electronic conductivity of LSC, which greatly improves the electrolysis side performance.

[0037] The present invention will be further described in detail below with reference to specific embodiments and accompanying drawings. However, the scope of protection of the present invention is not limited to the contents described. Experimental methods in this embodiment that do not specify specific conditions are all carried out in accordance with conventional methods and conditions.

[0038] Example 1

[0039] Commercial Ni-YSZ|YSZ|GDC|LSC batteries were used as the base cells. These batteries were manufactured by Wuxi Zhongfu New Energy Co., Ltd., and their dimensions were 5cm × 5cm.

[0040] According to the stoichiometric ratio of PNCO, accurately weigh 1.74g of Pr(NO3)3·6H2O, 0.47g of Ni(NO3)2·6H2O and 0.17g of Co(NO3)2·6H2O and place them in a clean beaker; add 40mL of deionized water to the beaker and place the beaker on a constant temperature magnetic stirrer to stir evenly to obtain a clear and transparent mixed solution.

[0041] Complexation: Add 0.287g CA as a complexing agent to the above mixed solution, then place the mixed solution in an ultrasonic cleaner and sonicate for 30 minutes, then transfer it to a constant temperature magnetic stirrer and stir for 12 hours to finally obtain a clear and transparent PNCO precursor solution.

[0042] Impregnation-calcination: Using a pipette, 25 μL of PNCO precursor solution was evenly injected onto the surface of the LSC oxygen electrode of the base cell. After standing for 1 minute, the cell was placed in a vacuum drying oven for 1 hour to allow the precursor solution to fully penetrate into the LSC oxygen electrode framework. The impregnated cell was then placed in a sintering furnace for calcination. The calcination process was as follows: first, the temperature was increased to 400℃ at a rate of 2℃ / min and held for 30 minutes; then, the temperature was increased to 1000℃ at a rate of 5℃ / min and held for 2 hours. After calcination, the cell surface was cleaned with anhydrous ethanol, completing one impregnation-calcination cycle.

[0043] Preparation of composite electrodes with different loading capacities: The above impregnation-calcination cycle was repeated to prepare PNCO-LSC composite oxygen electrode cells with 1, 2, and 3 impregnation cycles, respectively. For ease of differentiation and characterization, they are denoted as PNCO. 1 -LSC battery (i.e., Ni-YSZ|YSZ|GDC|PNCO) 1 -LSC battery), PNCO2 -LSC battery (i.e., Ni-YSZ|YSZ|GDC|PNCO) 2 -LSC battery) and PNCO 3 -LSC battery (i.e., Ni-YSZ|YSZ|GDC|PNCO) 3 -LSC cell); at the same time, a base cell that has not been impregnated with PNCO is used as a control sample (denoted as bare LSC cell, i.e. Ni-YSZ|YSZ|GDC|LSC cell).

[0044] For bare LSC cells, PNCO 1 -LSC battery, PNCO 2 -LSC batteries and PNCO 3 The microstructure of the oxygen electrode surface of the -LSC cell was observed, and the following results were obtained. Figure 1 Among them, (a) shows the oxygen electrode surface of the bare LSC cell, which is smooth and flat, with a uniformly distributed pore structure in the electrode framework and no obvious attached particles; (b) shows the PNCO... 1 - The surface microstructure of the oxygen electrode surface of the LSC battery shows that after one PNCO impregnation, the surface of the LSC oxygen electrode framework begins to become rough, with a small amount of PNCO particles adhering to it; (c) shows the PNCO... 2 -Surface microstructure of the oxygen electrode surface of the LSC cell, (d) is PNCO 3 The microstructure of the oxygen electrode surface of the LSC cell shows that with increasing impregnation cycles, the roughness of the LSC framework surface further increases, and PNCO particles uniformly cover and form a continuous thin film on the LSC framework surface. These morphological changes indicate that the solution impregnation method can achieve effective loading of PNCO on the LSC oxygen electrode surface, and the number of impregnation cycles directly affects the PNCO loading and the film formation state.

[0045] Bare LSC cells and PNCO were compared separately. 2 The electrochemical performance of the LSC cell in solid oxide fuel cell mode was tested under the following conditions: hydrogen flow rate at the hydrogen electrode side was 256 mL·min. -1 The flow rate of H2 introduced to the oxygen electrode side is 1280 mL·min. -1 Dry air was used for testing, with a temperature range of 700℃-800℃. The IVP curves of the batteries were recorded, and the results were obtained. Figure 2 and Figure 3 .

[0046] Figure 2The graph shows the IVP (Input Power Density) curves of the bare LSC battery at temperatures of 700℃, 750℃, and 800℃. The trend of the curves shows that the battery's output power density gradually increases with increasing test temperature; specifically, at 700℃, the peak power density of the battery is 0.591 W·cm³. -2 At 750℃, the peak power density increases to 0.696 W·cm³. -2 At 800℃, the peak power density reaches 0.760 W·cm³. -2 This demonstrates the positive impact of temperature on the power generation performance of bare LSC cells.

[0047] Figure 3 For PNCO 2 - IVP curves of the LSC battery output over temperature ranges of 700°C, 750°C, and 800°C. (Compared to...) Figure 2 In comparison, PNCO 2 - The peak power density of the LSC battery was significantly higher than that of the bare LSC battery at the same test temperature; specifically, the peak power density was 0.767 W·cm³ at 700℃. -2 At 750℃, the peak power density is 0.879 W·cm³. -2 At 800℃, the peak power density reaches 0.995 W·cm³. -2 This demonstrates that the composite modification of PNCO and LSC effectively improves the electrochemical output performance of the battery in fuel cell mode.

[0048] To further analyze the influence of the composite oxygen electrode on the battery polarization characteristics, bare LSC cells and PNCO cells were subjected to polarization tests at 800℃ and open-circuit voltage conditions. 2 -LSC cells were subjected to electrochemical impedance spectroscopy (EIS) measurements to obtain... Figure 4 The area enclosed by the curve and the horizontal axis in the graph reflects the polarization impedance of the battery. From the graph, the polarization impedance of the bare LSC battery can be directly read as 2.725 Ω·cm. 2 , and PNCO 2 The polarization impedance of the -LSC cell is 2.016 Ω·cm. 2 PNCO 2 The polarization impedance of the PNCO-LSC cell is significantly lower than that of the bare LSC cell, indicating that the PNCO-LSC composite oxygen electrode effectively reduces the polarization loss of the cell and improves the charge transport efficiency.

[0049] In solid oxide electrolysis cell mode, bare LSC cells and PNCO 1 -LSC battery, PNCO 2 -LSC batteries and PNCO 3The performance of the -LSC battery in electrolyzing CO2 was tested under the following conditions: the flow rate introduced to the hydrogen electrode side was 128 mL·min. -1 CO2 and 20 mL·min -1 H2 was used, and the test temperature was 800℃. The IV curve of the battery was recorded, and the following results were obtained. Figure 5 The curves show that, under the same electrolysis voltage, the current density of the PNCO-LSC series composite electrode cells is higher than that of the bare LSC cells. When the electrolysis voltage is 1.5V, the specific current densities of each cell are: bare LSC cell 0.656 A·cm⁻¹ -2 PNCO 1 -LSC battery 0.859A·cm -2 PNCO 2 -LSC battery 0.917A·cm -2 PNCO 3 -LSC battery 0.792A·cm -2 Among them, PNCO 2 The -LSC cell exhibited the highest current density, approximately 40% higher than the bare LSC cell, indicating that the PNCO loading formed by the two impregnation processes was the optimal loading, maximizing the reactivity of CO2 electrolysis; while PNCO 3 -LSC cells have a slightly lower current density than PNCO cells. 2 -LSC cells are presumably affected by the accumulation of PNCO film after three impregnations, which partially blocks the oxygen electrode channels and affects the transport efficiency of reactants / products.

[0050] To further analyze the polarization loss during CO2 electrolysis, electrochemical impedance spectroscopy (EIS) tests were conducted on the four types of batteries under CO2 electrolysis conditions at 800℃ and open-circuit voltage. Figure 6 As can be observed from the figure, the polarization resistance of the bare LSC cell is 0.284 Ω·cm. 2 , and PNCO 2 -LSC cells have the lowest polarization resistance, at 0.208 Ω·cm. 2 PNCO 1 -LSC batteries and PNCO 3 - The polarization resistance of an LSC cell lies between these two values. This result is consistent with... Figure 5 The IV curves show a consistent trend, further demonstrating that the PNCO-LSC composite oxygen electrode can reduce polarization losses during CO2 electrolysis. Among these, PNCO... 2 The optimal performance of the -LSC composite electrode is related to its combination of good catalytic activity and pore transport characteristics.

[0051] For the best performing PNCO 2- The LSC battery underwent long-term stability testing for CO2 electrolysis under the following conditions: electrolysis temperature 800℃, and the gas composition and flow rate were air 1280 mL·min. -1 CO2 128 mL·min -1 H2 20 mL·min -1 At a constant 400 mA·cm -2 The current density was continuously tested for 100 hours, and the voltage change curve of the battery was recorded to obtain... Figure 7 The curve shows that the battery's operating voltage was 1.017V at the initial test stage (0h), and slowly increased with the test time, reaching 1.088V at 100h. The calculated voltage decay rate of the battery is 7.1 × 10⁻⁶. -4 V·h -1 During the 100-hour long-term test, the battery voltage did not exhibit drastic fluctuations or significant increases, indicating that the PNCO-LSC composite oxygen electrode possesses good structural and catalytic stability, meeting the application requirements for long-term CO2 electrolysis.

[0052] In summary, this invention prepares the PNCO-LSC composite oxygen electrode via a solution impregnation method. The process is simple and controllable. By optimizing the number of PNCO impregnation cycles (optimally two), the power generation performance of the reversible solid oxide battery in fuel cell mode and its CO2 electrolysis performance in electrolyzer mode can be significantly improved, while ensuring excellent long-term battery stability. This provides a feasible technical solution for the efficient resource utilization of CO2. Thus, the oxygen electrode material provided by this invention exhibits high catalytic activity and high stability. The high catalytic activity includes improved catalytic efficiency for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), accelerating the rates of both reactions, reducing polarization losses, and adapting to the dual-mode operation requirements of reversible solid oxide batteries in both SOEC and SOFC modes.

[0053] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention. Various variations can be made to the above embodiments of the present invention. That is, all simple and equivalent changes and modifications made based on the claims and description of this invention fall within the protection scope of the claims. All aspects not described in detail in this invention are conventional technical content.

Claims

1. A method for preparing a composite oxygen electrode for a reversible solid oxide battery, characterized in that, The preparation method includes the following steps: S1, according to the stoichiometric ratio of PNCO, weigh out soluble salts containing praseodymium, nickel and cobalt and dissolve them in water to obtain a mixed solution; S2, add a complexing agent to the mixed solution, sonicate and then stir to obtain PNCO precursor solution; S3, the PNCO precursor solution is transferred to the surface of the LSC oxygen electrode for vacuum impregnation; S4. The impregnated battery is placed in a sintering furnace and calcined. The impregnation and calcination cycle of steps S3 and S4 is repeated to obtain the PNCO-LSC composite oxygen electrode.

2. The preparation method according to claim 1, characterized in that, In step S1, the praseodymium-containing soluble salt is praseodymium nitrate hexahydrate, the nickel-containing soluble salt is nickel nitrate hexahydrate, and the cobalt-containing soluble salt is cobalt nitrate hexahydrate; the molar fraction of praseodymium nitrate hexahydrate, nickel nitrate hexahydrate, and cobalt nitrate hexahydrate is 5%-90%.

3. The preparation method according to claim 1, characterized in that, In step S2, the complexing agent is selected from at least one of citric acid, ethylenediaminetetraacetic acid, polyvinylpyrrolidone, hexadecyltrimethylammonium bromide, and sodium succinate; the molar ratio of the complexing agent to PNCO is 0.6:1-1.2:1, and the concentration of the PNCO precursor solution is 0.001-0.1 mol·L⁻¹. -1 .

4. The preparation method according to claim 1, characterized in that, In step S3, the LSC oxygen electrode comes from a Ni-YSZ|YSZ|GDC|LSC cell, where YSZ is yttrium-doped zirconium oxide and GDC is gadolinium-doped cerium oxide.

5. The preparation method according to claim 1, characterized in that, In step S3, the volume of PNCO precursor liquid used for each impregnation is 5-100 μL, and the effective impregnation area of ​​the battery LSC oxygen electrode is 4 cm × 4 cm - 6 cm × 6 cm.

6. The preparation method according to claim 1, characterized in that, In step S4, the calcination process is as follows: the temperature is increased to 300-600℃ at a programmed heating rate of 1℃ / min-5℃ / min, and held for 0.1-5h; then the temperature is increased to 900-1100℃ at a programmed heating rate of 1-5℃ / min, and sintered for 0.1-5h.

7. The preparation method according to claim 1, characterized in that, In step S4, the number of impregnation and calcination cycles is 2-6.

8. A reversible solid oxide battery composite oxygen electrode, characterized in that, The preparation method according to any one of claims 1-7 yields a product comprising an LSC substrate layer and a PNCO active layer coating the surface of the LSC substrate layer.

9. An application of the reversible solid oxide battery composite oxygen electrode according to claim 8, characterized in that, This application covers both solid oxide fuel cell and solid oxide electrolyzer modes.

10. The application according to claim 9, characterized in that, This application includes its use in the resource utilization of electrolytic carbon dioxide.

Images