A cathode electrocatalyst for a solid oxide fuel cell, a preparation method thereof, and an application thereof

Abstract

The present invention discloses a cathode electrocatalyst for a solid oxide fuel cell, a preparation method thereof, and an application thereof. Among them, the material of the cathode electrocatalyst for the solid oxide fuel cell is BCFZY-GDC-PrO x , where BCFZY is BaCo 0.4 Fe 0.4 Zr 0.1 Y 0.1 O 3‑δ , GDC is Ce 0.8 Gd 0.2 O 1.9 . The present invention mainly improves the catalytic activity of the cathode by improving the material of the cathode electrocatalyst for the solid oxide fuel cell, thereby improving the power density of the SOFC. Specifically, the present invention impregnates PrO x nanoparticles into the BCFZY-GDC composite cathode coating, thereby improving the oxygen ion exchange performance of the composite cathode during the ORR (oxidation-reduction) process, and the impregnation of PrO x can also greatly improve the power density of the single cell.

Description

Technical Field

[0001] The present invention relates to the technical field of solid oxide fuel cells, and particularly to a cathode electrocatalyst for a solid oxide fuel cell, a preparation method thereof, and an application thereof. Background Art

[0002] Solid oxide fuel cells (SOFCs) have received extensive attention as a green energy technology due to their excellent fuel flexibility and conversion efficiency. Using alkane fuels in solid oxide fuel cells is a development trend for the efficient and clean conversion of light alkanes through SOFCs, which has important national energy security strategic significance. In the past decade, the synthesis of value-added chemicals using solid oxide fuel cell reactors has attracted extensive attention from researchers. With further exploration of various materials and processes of SOFCs by researchers, more fuel gases are available for SOFCs, making the SOFC with co-generation of electric energy and chemicals more industrially significant. However, the catalytic activity of the existing cathode materials of SOFCs is poor, resulting in a low power density of SOFCs, which limits the application of SOFCs.

[0003] Therefore, the existing technology still needs to be improved and developed. Summary of the Invention

[0004] In view of the above deficiencies of the existing technology, the purpose of the present invention is to provide a cathode electrocatalyst for a solid oxide fuel cell, a preparation method thereof, and an application thereof, aiming to solve the problem that the catalytic activity of the existing cathode materials of SOFCs is poor, resulting in a low power density of SOFCs, which limits the application of SOFCs.

[0005] The technical solution of the present invention is as follows:

[0006] A cathode electrocatalyst for a solid oxide fuel cell, wherein the material of the cathode electrocatalyst for the solid oxide fuel cell is BCFZY-GDC-PrO x wherein BCFZY is BaCo 0.4 Fe 0.4 Zr 0.1 Y 0.1 O 3-δ and GDC is Ce 0.8 Gd 0.2 O 1.9 .

[0007] A preparation method of a cathode electrocatalyst for a solid oxide fuel cell, which includes the steps of:

[0008] Weigh BCFZY, GDC and PEG, add them into a polytetrafluoroethylene tank, add zirconium balls and ethanol thereto, and then perform ball milling treatment to obtain a BCFZY-GDC composite cathode slurry;

[0009] The BCFZY-GDC composite cathode paste is coated on the surface of the half-cell or the electrolyte by screen printing, and then placed in a muffle furnace for the first calcination treatment to obtain a BCFZY-GDC composite cathode coating;

[0010] The Pr(NO3)3·6H2O solution is dropped onto the surface of the BCFZY-GDC composite cathode coating, and then placed in a muffle furnace for the second calcination treatment to prepare the cathode electrocatalyst of the solid oxide fuel cell.

[0011] The preparation method of the cathode electrocatalyst of the solid oxide fuel cell, wherein the temperature of the first calcination treatment is 900 - 100 °C, and the time is 4 - 6 h.

[0012] The preparation method of the cathode electrocatalyst of the solid oxide fuel cell, wherein the temperature of the second calcination treatment is 750 - 850 °C, and the time is 1 - 3 h.

[0013] The preparation method of the cathode electrocatalyst of the solid oxide fuel cell, wherein the steps of weighing BCFZY, GDC and PEG and adding them into a polytetrafluoroethylene tank, adding zirconium balls and ethanol thereto, and then performing ball milling treatment to obtain the BCFZY-GDC composite cathode paste include:

[0014] Weigh BCFZY, GDC and PEG and add them into a polytetrafluoroethylene tank, add zirconium balls and ethanol thereto, seal it with transparent tape, then place it in a quartz boat and put it into a ball mill for ball milling treatment;

[0015] After ball milling is completed, take it out, sieve it, and dry it in an oven at 50 - 80 °C, then grind it again for 10 - 30 min, and collect the BCFZY-GDC composite cathode paste.

[0016] The preparation method of the cathode electrocatalyst of the solid oxide fuel cell, wherein the speed of the ball milling treatment is 100 - 150 r / min, and the ball milling time is 20 - 28 h.

[0017] The preparation method of the cathode electrocatalyst of the solid oxide fuel cell, wherein in the step of dropping the Pr(NO3)3·6H2O solution onto the surface of the BCFZY-GDC composite cathode coating, the amounts of the titrated Pr(NO3)3·6H2O solution are 20 μl / cm 2 , 40 μl / cm 2 , 60 μl / cm 2 and 80 μl / cm 2 .

[0018] Application of a cathode electrocatalyst for a solid oxide fuel cell, wherein the cathode electrocatalyst for the solid oxide fuel cell is used to prepare a solid oxide fuel cell.

[0019] Beneficial effects: The present invention mainly improves the cathode of the solid oxide fuel cell to enhance the catalytic activity of the composite cathode, thereby enhancing the power density of the SOFC. Specifically, the present invention impregnates PrO x nanoparticles into the BCFZY-GDC composite cathode coating, thereby improving the oxygen ion exchange performance of the composite cathode during the ORR (oxidation-reduction) process, and the impregnation of PrO x can also greatly improve the power density of the single cell. Description of the drawings

[0020] Figure 1a XRD patterns of BCFZY, GDC, BCFZY-GDC composite material, and BCFZY-GDC-PrO x composite cathode material.

[0021] Figure 1b XRD refined pattern of BCFZY material.

[0022] Figure 1c XRD refined pattern of BCFZY-GDC composite material.

[0023] Figure 1d XRD refined pattern of BCFZY-GDC-PrO x composite cathode material.

[0024] Figure 1e TEM morphology image of BCFZY-GDC-PrO x composite cathode material.

[0025] Figure 1f High-resolution TEM image of BCFZY-GDC-PrO x composite cathode material.

[0026] Figure 1g For Figure 1f Magnified view of area A in

[0027] Figure 1h For Figure 1f Magnified view of area B in

[0028] Figure 1i For Figure 1f EDS spectrum of area B in

[0029] Figure 2 XRD patterns of BCFZY-GDC-PrO xTEM-EDS energy spectrum surface scan images of the composite cathode material, where a is the TEM micrograph of the BCFZY-GDC-PrOx composite powder, b-j are the TEM-EDS elemental surface scan images respectively, and k-l are PrO x TEM-EDSs line scan images of the interface between PrO nanoparticles and the BCFZY matrix.

[0030] Figure 3a Before and after the BCFZY matrix infiltrates PrO x Co 2p before and after infiltrating PrO nanoparticles 3 / 2 and Ba3d 5 / 2 XPS photoelectron spectra.

[0031] Figure 3b Before and after the BCFZY matrix infiltrates PrO x Fe 2p before and after infiltrating PrO nanoparticles 3 / 2 XPS photoelectron spectra.

[0032] Figure 3c Before and after the BCFZY matrix infiltrates PrO x XPS photoelectron spectra of O1s before and after infiltrating PrO nanoparticles

[0033] Figure 3d Before and after the BCFZY matrix infiltrates PrO x XPS photoelectron spectra of c 1s before and after infiltrating PrO nanoparticles

[0034] Figure 3e Before and after the BCFZY matrix infiltrates PrO x Variation diagrams of adsorbed oxygen and lattice oxygen on the sample surface before and after infiltrating PrO nanoparticles

[0035] Figure 4a Before and after the BCFZY matrix penetrates PrO x Test result diagrams of the sample conductivity performance

[0036] Figure 4b Before and after the BCFZY matrix penetrates PrO x ECR diagrams of the sample at 450 - 600 °C after penetration

[0037] Figure 4c Before and after the BCFZY matrix penetrates PrO x Comparison diagrams of ECR of the sample at 500 °C

[0038] Figure 4d Before and after the BCFZY matrix penetrates PrO x Comparison diagrams of ECR of the sample at 600 °C

[0039] Figure 4e Before and after the BCFZY matrix penetrates PrO xComparison diagram of oxygen ion bulk diffusion (D chem ) of the samples before and after.

[0040] Figure 4f For the BCFZY matrix infiltrated with PrO x Comparison diagram of surface diffusion (K chem ) of the samples before and after.

[0041] Figure 4g For the BCFZY matrix infiltrated with PrO x After that, at 500 °C 18 Schematic diagram of ToF-SIMS after O exchange.

[0042] Figure 4h For the BCFZY matrix infiltrated with PrO x After that, in Figure 4g Selected area of 18 O distribution map.

[0043] Figure 4i For the BCFZY matrix infiltrated with PrO x After that, in Figure 4i Selected area of 18 O distribution map.

[0044] Figure 4j For the BCFZY matrix infiltrated with PrO x After that, in Figure 4i Selected area of Pr distribution map.

[0045] Figure 5a For the BCFZY matrix impregnated with PrO x Comparison diagram of ECR performance before and after at 450 °C.

[0046] Figure 5b For the BCFZY matrix impregnated with PrO x Comparison diagram of ECR performance before and after at 500 °C.

[0047] Figure 5c For the BCFZY matrix impregnated with PrO x Comparison diagram of ECR performance before and after at 550 °C.

[0048] Figure 5d For the BCFZY matrix impregnated with PrO x Comparison diagram of ECR performance before and after at 600 °C.

[0049] Figure 6a For the polarization resistance comparison diagram of (Pr0) / GDC / (Pr0) symmetric cells under different temperature conditions.

[0050] Figure 6bPolarization resistance comparison diagram of (Pr20) / GDC / (Pr20) symmetric battery under different temperature conditions.

[0051] Figure 6c Polarization resistance comparison diagram of (Pr40) / GDC / (Pr40) symmetric battery under different temperature conditions.

[0052] Figure 6d Polarization resistance comparison diagram of (Pr60) / GDC / (Pr60) symmetric battery under different temperature conditions.

[0053] Figure 6e Polarization resistance comparison diagram of (Pr80) / GDC / (Pr80) symmetric battery under different temperature conditions.

[0054] Figure 6f Polarization resistance comparison diagram of (Pr0-Pr80) / GDC / (Pr0-Pr80) symmetric battery at 600 °C.

[0055] Figure 7a R of different cathode materials of (Pr0-Pr80) / GDC / (Pr0-Pr80) symmetric battery at working temperature of 500 - 700 °C p Comparison diagram.

[0056] Figure 7b Polarization resistance comparison diagram of different cathode materials of (Pr0-Pr80) / GDC / (Pr0-Pr80) symmetric battery at 600 °C working temperature.

[0057] Figure 7c DRT analysis comparison diagram of different cathode materials of (Pr0-Pr80) / GDC / (Pr0-Pr80) symmetric battery at 600 °C working temperature.

[0058] Figure 7d R of (Pr0-Pr80) / GDC / (Pr0-Pr80) symmetric battery in the range of 500 - 700 °C p Arrhenius plot of reciprocal.

[0059] Figure 7e Single cell power density of Ni-YSZ / YSZ / GDC / (Pr0, Pr20, Pr40, Pr60, Pr80).

[0060] Figure 7f For BCFZY-GDC-PrO x (Pr60) as the cathode of the single cell power density.

[0061] Figure 7gThe graph of the single cell performance stability test results for the single cell configured with Ni-YSZ / YSZ / GDC / Pr60 at a working temperature of 600 °C under the condition of constant voltage of 0.85 V for about 270 h.

[0062] Figure 7h SEM image of a 20-μm cross-section of the single cell configured with Ni-YSZ / YSZ / GDC / Pr60 after the stability test.

[0063] Figure 7i SEM image of a 1-μm cross-section of the single cell configured with Ni-YSZ / YSZ / GDC / Pr60 after the stability test.

[0064] Figure 8 For BCFZY-GDC-PrO x SEM cross-sectional micrograph of the composite cathode, where a is the SEM cross-sectional micrograph of BCFZY-GDC-PrO 2 when the titrated amount of Pr(NO3)3·6H2O solution is 20 μl / cm x SEM cross-sectional micrograph of the composite cathode; b is the SEM cross-sectional micrograph of BCFZY-GDC-PrO 2 when the titrated amount of Pr(NO3)3·6H2O solution is 40 μl / cm x SEM cross-sectional micrograph of the composite cathode; c is the SEM cross-sectional micrograph of BCFZY-GDC-PrO 2 when the titrated amount of Pr(NO3)3·6H2O solution is 60 μl / cm x SEM cross-sectional micrograph of the composite cathode; d is the SEM cross-sectional micrograph of BCFZY-GDC-PrO 2 when the titrated amount of Pr(NO3)3·6H2O solution is 80 μl / cm x SEM cross-sectional micrograph of the composite cathode.

[0065] Figure 9a Power density of the single cell composed of a commercial Ni-YSZ anode and a BCFZY-GDC cathode without infiltrated PrO x

[0066] Figure 9b Power density of the single cell supported by a commercial Ni-YSZ anode and composed of BCFZY-GDC-PrO 2 when the titrated amount of Pr(NO3)3·6H2O is 20 μl / cm x composite cathode.

[0067] Figure 9c Power density of the single cell supported by a commercial Ni-YSZ anode and composed of BCFZY-GDC-PrO 2 when the titrated amount of Pr(NO3)3·6H2O is 40 μl / cmx Power density of a single cell composed of a composite cathode.

[0068] Figure 9d For a commercial Ni-YSZ anode-supported BCFZY-GDC-PrO with a titration of Pr(NO3)3·6H2O of 60 μl / cm 2 at x Power density of a single cell composed of a composite cathode.

[0069] Figure 9e For a commercial Ni-YSZ anode-supported BCFZY-GDC-PrO with a titration of Pr(NO3)3·6H2O of 80 μl / cm 2 at x Power density of a single cell composed of a composite cathode.

[0070] Figure 9f Power density comparison chart of single cells for Ni-YSZ / YSZ / GDC / Pr0, Pr20, Pr40, Pr60, and Pr80. Detailed implementation

[0071] The present invention provides a cathode electrocatalyst for a solid oxide fuel cell and a preparation method thereof. To make the purpose, technical solution, and effects of the present invention clearer and more definite, the present invention is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0072] The present invention provides a cathode electrocatalyst for a solid oxide fuel cell, wherein the material of the cathode electrocatalyst for the solid oxide fuel cell is BCFZY-GDC-PrO x , wherein BCFZY is BaCo 0.4 Fe 0.4 Zr 0.1 Y 0.1 O 3-δ , GDC is Ce 0.8 Gd 0.2 O 1.9 .

[0073] The present invention also provides a solid oxide fuel cell, which includes a solid electrolyte and an anode and a composite cathode located on both sides of the solid electrolyte. The composite cathode is the cathode electrocatalyst for the solid oxide fuel cell, and its material is BCFZY-GDC-PrO x , wherein BCFZY is BaCo 0.4 Fe 0.4 Zr 0.1 Y 0.1 O 3-δ , GDC is Ce 0.8Gd 0.2 O 1.9 。

[0074] The present invention mainly improves the cathode of a solid oxide fuel cell to enhance the catalytic activity of the composite cathode, thereby increasing the power density of the SOFC. Specifically, the present invention impregnates PrO x nanoparticles into the BCFZY-GDC composite cathode coating, thereby improving the oxygen ion exchange performance during the ORR (oxidation-reduction) process of the composite cathode, and the impregnation of PrO x can also greatly increase the power density of the single cell.

[0075] In some embodiments, a method for preparing a solid oxide fuel cell is also provided, which includes the steps of: providing a composite cathode, the material of the composite cathode being BCFZY-GDC-PrO x , wherein BCFZY is BaCo 0.4 Fe 0.4 Zr 0.1 Y 0.1 O 3-δ , GDC is Ce 0.8 Gd 0.2 O 1.9 ; printing the composite cathode and the anode on both sides of the solid electrolyte, and connecting the composite cathode and the anode through a wire to obtain the solid oxide fuel cell.

[0076] In this embodiment, the preparation of the composite cathode includes the steps of: weighing BCFZY, GDC and PEG and adding them into a polytetrafluoroethylene tank, adding zirconia balls and ethanol thereto, sealing it with transparent tape and placing it in a quartz boat and putting it into a ball mill for ball milling treatment, the speed of the ball milling treatment being 100 - 150 r / min and the ball milling time being 20 - 28 h; taking it out and sieving after ball milling and drying it in an oven at 50 - 80 °C, then grinding it again for 10 - 30 min to collect the BCFZY-GDC composite cathode slurry; using the screen printing method to coat the BCFZY-GDC composite cathode slurry on the surface of the half cell or the electrolyte surface, and placing it in a muffle furnace for the first calcination treatment to obtain the BCFZY-GDC composite cathode coating; dropping the Pr(NO3)3·6H2O solution onto the surface of the BCFZY-GDC composite cathode coating, and then placing it in a muffle furnace for the second calcination treatment to obtain the composite cathode, the amounts of the dropped Pr(NO3)3·6H2O solution being 20 μl / cm 2 , 40 μl / cm 2 , 60 μl / cm 2 and 80 μl / cm 2 .

[0077] Preferably, in this embodiment, the temperature of the first calcination treatment is 900 - 100°C, and the time is 4 - 6 h, but not limited thereto; the temperature of the second calcination treatment is 750 - 850°C, and the time is 1 - 3 h, but not limited thereto.

[0078] The following further explains the present invention through specific embodiments:

[0079] Preparation of BCFZY cathode powder:

[0080] The raw material ratio is shown in Table 1. Measure 45 mL of nitric acid into a 1 L beaker containing about 400 ml of deionized water, set the stirring rate to 450 r / min, and then orderly add the weighed raw materials into the beaker (each time a raw material is added, the next raw material can only be added after the previous raw material is completely dissolved). After stirring for 20 minutes, adjust the pH value to about 7.2 with ammonia water, then continue stirring for 4 h, heat to about 150°C to evaporate the water. When there is about 150 mL of solution left in the beaker, transfer the solution to an evaporating dish and continue to evaporate the solution to dryness. Finally, obtain a black BCFZY powder, and then keep this powder at 950°C for 300 minutes for later use.

[0081] Table 1 Raw material ratio of BCFZY perovskite cathode material

[0082]

[0083]

[0084] GDC (Ce 0.8 Gd 0.2 O 1.9 ) Preparation of powder:

[0085] The raw material ratio is shown in Table 2. Measure 50 mL of nitric acid into a 1 L beaker containing about 350 ml of deionized water, set the stirring rate to 500 r / min, and then orderly add the weighed raw materials into the beaker (each time a raw material is added, the next raw material can only be added after the previous raw material is completely dissolved). After stirring for 20 minutes, adjust the pH value to about 7.2 with ammonia water, then continue stirring for 4 h, heat to about 150°C to evaporate the water. When there is about 150 mL of solution left in the beaker, transfer the solution to an evaporating dish and continue to evaporate the solution to dryness. Finally, obtain a milky white GDC powder, and then keep this powder at 800°C for 120 minutes for later use.

[0086] Table 2 Raw material ratio of GDC powder material

[0087] Raw material Calculation amount (g) First portion taken (g) Second portion taken (g) <![CDATA[99.95% Ce(NO3)3·6H2O]]> 34.7550 34.7565 34.7562 <![CDATA[99.9% Gd(NO3)3·6H2O]]> 9.0362 9.0373 9.0364 Citric acid 28.9628 28.9628 28.9631 EDTA 29.3709 29.3708 29.3711

[0088] Preparation of BCFZY - GDC composite cathode material:

[0089] Weigh 1.800 g of BCFZY, 1.200 g of GDC and 1.579 g of PEG into a polytetrafluoroethylene tank. Add 5 mm zirconium balls to it and add ethanol until the samples and zirconium balls are completely submerged. Seal it with transparent tape and place it in a quartz boat, then put it into a ball mill and ball mill at 120 r / min for 24 h. Then take it out, sieve it, dry it in an oven at 60 °C, and then grind it for 20 min to collect the BCFZY-GDC composite cathode paste. Subsequently, the cathode paste was coated on the surface of the Ni-YSZ / YSZ / GDC half-cell or the GDC electrolyte surface by screen printing, and then placed in a muffle furnace and calcined at 950 °C for 5 hours to obtain the BCFZY-GDC composite cathode material.

[0090] BCFZY-GDC-PrO x Preparation of the composite cathode material:

[0091] First, prepare a 0.3 M Pr(NO3)3·6H2O solution. Use a pipette to drop the Pr(NO3)3·6H2O solution onto the calcined BCFZY-GDC composite cathode coating. The volumes of the titrated solutions are 20 μl / cm 2 , 40 μl / cm 2 , 60 μl / cm 2 and 80 μl / cm 2 . Then, place the titrated cell pieces in a muffle furnace for calcination treatment. The calcination temperature is 800 °C and the holding time is 2 hours. Subsequently, follow-up electrochemical performance tests are carried out.

[0092] The main performance characterization methods of the composite cathode material include:

[0093] 1), Conductivity characterization:

[0094] The conductivity of the sample is measured by the four-terminal method. First, press the prepared powder into a bar and sinter it at high temperature. Then, fix silver wires at both ends of the bar-shaped sample as current electrodes, and fix two silver wires in the middle of the bar-shaped sample as voltage electrodes. Place the sample in a quartz tube. When the temperature is raised to 700 °C, use a Keithley digital multimeter to start recording the resistance R value of the sample. Measure one data point every 50 °C drop in temperature until 500 °C. Then switch the oxygen partial pressure of the test atmosphere, repeat the above steps, record the change in the resistance value of the sample under different oxygen partial pressure atmospheres, and finally substitute the measured resistance value R into the following equation to calculate the conductivity σ value of the sample: Where, L is the distance between the two voltage wires in the middle of the bar-shaped sample, and A is the cross-sectional area of the bar-shaped sample.

[0095] 2), Oxygen ion exchange performance characterization:

[0096] ①Electrical conductivity relaxation method (ECR): Using the standard four-terminal method, the exchange coefficients of oxygen ions on the surface and in the bulk of the sample are determined by recording the electrical conductivity relaxation process. The detailed steps are as follows: The sample preparation method is the same as that for the above electrical conductivity test. The prepared strip-shaped sample is placed in a quartz tube, heated to 700 °C, and then 21% O2 - 79% Ar gas is introduced. When its electrical conductivity reaches equilibrium and stability, the atmosphere is switched to 10% O2 - 90% Ar atmosphere (the gas flow rate is set to 100 ml min -1 ), due to the change in the oxygen partial pressure of the atmosphere, the electrical conductivity of the sample and the atmosphere will undergo a re-equilibration process. When the oxygen partial pressure is switched, a Keithley digital multimeter is used to record the change in the electrical conductivity of the sample, and then MATLAB software is used to fit the electrical conductivity relaxation data to obtain the oxygen ion diffusion coefficients in the bulk and on the surface of the sample. Finally, repeat the above steps to measure the electrical conductivity relaxation curves and oxygen ion diffusion coefficients at 700 °C, 650 °C, 600 °C, 550 °C, and 500 °C respectively.

[0097] ② 18 O isotope tracing method: First, the synthesized powder is pressed into a disc and subjected to high-temperature sintering. Then, the sample is placed in a quartz tube and heated to 500 °C at a rate of 10 °C / min. Then, the air in the tube is evacuated with argon, and 18 O2 isotope is introduced for 15 seconds, and then held at a constant temperature for 5 minutes and cooled to room temperature. The 18 O2 / 16 O2 exchange degree on the surface and cross-section of the sample is tested by time-of-flight secondary ion mass spectrometry (TOF-SIMS) to analyze and evaluate the oxygen ion exchange rates on the surface and in the bulk of the sample.

[0098] 3) Electrochemical performance characterization

[0099] The prepared solid oxide battery slices are evaluated for their electrochemical performance. First, the battery slice is sealed with ceramic glue to a ceramic tube, with the anode of the battery slice facing down and the cathode facing up, and the battery is heated to the operating temperature (700 °C); then, argon is introduced on the anode side to evacuate, and after 15 minutes, it is switched to H2, and the OCV value of the battery is checked. If the OCV of the battery at 700 °C is above 1.09, it proves that the battery is well-sealed and the next test can be carried out. The electrochemical performance of the battery, including the voltage-current density curve, AC impedance spectrum, and chronopotentiometry curve (CP) of the SOFC, etc., is measured using a Solartron electrochemical workstation. The interfacial thermal stability and chemical stability between the cathode material and the electrolyte material after testing are analyzed using high-resolution scanning electron microscopy (HR-SEM) and energy spectrum analysis technology.

[0100] BCFZY-GDC-PrO x Phase and chemical compatibility analysis of the composite cathode powder: Such as Figure 1a - 1iAs shown, the BCFZY powder with a body-centered cubic space group structure (Pm-3m) was successfully prepared and has good chemical compatibility with the GDC electrolyte powder. When the Pr(NO3)3·6H2O solution was immersed in the BCFZY-GDC composite cathode material and calcined at 800 °C for 2 hours, PrO x phase was clearly observed, and no obvious impurity phase peaks appeared, indicating that there is good chemical compatibility and structural stability between the BCFZY-GDC composite cathode material and PrO x particles. The XRD refinement results further revealed that the unit cell parameters of BCFZY in the composite cathode material did not change significantly, as shown in Table 3.

[0101] Table 3 Parameter changes in the refinement results of the BCFZY phase before and after composition

[0102]

[0103]

[0104] Figure 1e - Figure 1i Figure is the TEM pattern of the BCFZY-GDC-PrO x composite cathode material. As can be seen from the figure, the grain size of the composite particles is between 50 - 100 nm. The high-resolution TEM pattern further confirmed the presence of BCFZY and PrO x particles, and the particles are well combined. This structural feature will contribute to the improvement of the thermal stability of the material at high temperatures.

[0105] Figure 2 Figure is the TEM-EDS energy spectrum surface scan of the composite cathode material. As can be seen from the figure, the distribution of each element is uniform, especially PrO x particles are evenly distributed on the surface of the BCFZY-GDC composite cathode material. The interface line scan further shows that part of the Pr element in the PrO x particles penetrates into the matrix material, and elements such as Co and Fe in the matrix material also partially penetrate into the PrO x particles. Since the degree of mutual diffusion is not large, it does not cause obvious changes in the structural parameters of PrO x and the matrix material. As shown in Table 3, before impregnation, the unit cell volume of BCFZY was After impregnating PrOx, its unit cell volume did not change significantly, being

[0106] The surface chemical properties of the BCFZY matrix before and after infiltrating PrO x nanoparticles were analyzed by XPS. As Figure 3a and Figure 3b shown, in PrO xIn the presence of [substance], the average valence states of Co and Fe elements decrease slightly, which is related to Figure 2 the diffusion of a small amount of Pr element into the BCFZY particles in x (since the valence states of Pr element are usually 3+ and 4+, in order to compensate the valence states well, the valence states of variable valence transition metals will decrease slightly). The infiltrated PrO Figure 3c will also slightly reduce the binding energy of lattice oxygen. As x shown, in the absence of PrO x , the binding energy of lattice oxygen is about 528.9 eV, while that of the sample infiltrated with PrO

[0107] is about 528.6 eV. The low binding energy of lattice oxygen is beneficial to the exchange and transfer process of cathode oxygen ions. Figure 3c On the other hand, as - shown, the concentration of surface adsorbed oxygen (mainly adsorbed OH 2- and CO3 - ) also decreases with the infiltration of Pr element. Since the binding energies of OH 2- and CO3 - are almost the same, it is difficult to distinguish them only by X-ray photoelectron spectroscopy. The atomic ratio between the O component at 531.3 eV (OH 2- + CO3 x ) and the C1s component at 289.0 - 289.2 eV (only carbonate) can be used to clarify the above problem. It is calculated that the O / C ratios of the samples with and without the addition of PrO x are about 3.63 and 3.51 respectively, both slightly higher than the theoretical value estimated according to the stoichiometry of carbonate (O / C in carbonate is 3), indicating that the surface adsorbed O species are mainly composed of CO3 2- groups and there are fewer OH - groups. Obviously, the infiltrated PrO x will also prevent the chemisorption of CO2 molecules on the surface to a certain extent, as Figure 3e shown.

[0108] The conductivity and oxygen ion exchange performance of the samples after infiltrating PrO x are also evaluated in detail. As Figure 4a - 4j and 5a - 5d shown, although the infiltrated PrO x has little effect on the conductivity of the samples, it significantly accelerates the oxygen ion exchange characteristics, especially at lower temperatures (see Figure 4b - 4d ). For example, when the oxygen partial pressure is suddenly switched from 0.21 to 0.1 atm, at 500 °C, the conductivity equilibrium time of the sample without PrO x is about 2200 s, while that of the sample with PrO xThe sample conductivity equilibrium time is only about 1000 s (see Figure 4c ). In addition, the penetration of PrO x not only significantly accelerates the bulk diffusion (D chem ) and surface diffusion (K chem ) of oxygen ions, but also further significantly reduces the corresponding activation energy of oxygen ion diffusion. As can be seen from Figure 4e and 4f , without PrO x , the activation energies of D chem and K chem are about 46.4 and 45.3 kJ mol -1 respectively, while in the presence of PrO x , the activation energies of D chem and K chem are about 37.1 and 39.1 45.3 kJ mol -1 respectively. In addition, ToF-SIMS further confirms the excellent oxygen ion exchange performance brought by the penetration of PrO x . As shown in Figure 4g - 4j , a large amount of 18 O elements can be clearly observed in the selected area, especially around the Pr element.

[0109] The ORR performance of (P0-Pr80) / GDC / (P0-Pr80) symmetrical cells was evaluated in an atmospheric environment. As can be seen from Figure 6a - 6f , after the penetration of PrO x , the polarization resistance (R p ) of the sample is significantly reduced, especially in the lower temperature range of 500 °C to 600 °C. When the infiltration amount of Pr(NO3)3 solution is about 60 μl / cm -2 , the R p value reaches the lowest. At the operating temperature of 600 °C, the corresponding R p value is only about 0.082 Ω·cm 2 , which is only 25.3% of the composite cathode without infiltrating PrO x . In the present invention, Pr0 refers to PrO x without penetration, Pr20 refers to the infiltration amount of Pr(NO3)3 solution about 20 μl / cm -2 , Pr40 refers to the infiltration amount of Pr(NO3)3 solution about 40 μl / cm -2 , Pr60 refers to the infiltration amount of Pr(NO3)3 solution about 60 μl / cm -2 , and Pr80 refers to the infiltration amount of Pr(NO3)3 solution about 80 μl / cm -2 .

[0110] To further analyze the improved electrode performance, the EIS data of each sample was further analyzed by DRT software (see Figure 7c ). It can be seen that each curve can be divided into different peaks between high frequency and low frequency, and the area of each peak represents the impedance of the corresponding polarization process. High frequency (> 10 3 Hz), medium frequency (1 - 10 3 Hz) and low frequency (10 -2 - 1 Hz) characteristic peaks are respectively related to the charge transfer of oxygen ions from the electrolyte to the cathode at the three-phase reaction interface (TPBs), surface exchange or ion transfer on the cathode surface, and gas diffusion process. Obviously, with the increase of PrO x content in the composite cathode, the peak area corresponding to the medium frequency decreases significantly, indicating that the surface exchange and ion transfer in the cathode process are significantly enhanced. As Figure 7d shown, while the polarization resistance increases, their ORR activation energy also decreases significantly, which is consistent with the fact that the penetration of PrO x significantly accelerates their oxygen ion exchange characteristics. However, it should be noted that when the infiltration amount of Pr(NO3)3 solution is greater than 60 μl / cm -2 , the change of its polarization resistance is not obvious, which may be closely related to the aggregation of PrO x nanoparticles, as shown in a - d of Figure 8 .

[0111] Then, the prepared materials were used as SOFC cathodes for single cell tests to evaluate their power generation performance. As Figure 7e and Figure 9a - 9f shown, the impregnation of PrO x greatly improves the power density of the single cell. When the infiltration amount of Pr(NO3)3 solution is about 60 μl / cm -2 (see Figure 7f ), at 700 °C, 650 °C and 600 °C, the power density of the single cell with the Ni - YSZ / YSZ / GDC / Pr60 configuration can reach about 1.55, 1.02, 0.56 W cm -2 respectively, almost twice that of the single cell without impregnated PrO x , and comparable to the power density of single cells of other cathode materials with great application value. In addition, at the working temperature of 600 °C, under the condition of constant voltage 0.85 V for about 270 h, the single cell also shows excellent performance stability, and no obvious delamination phenomenon is found after electrochemical testing (see Figure 7g - 7i ).

[0112] In summary, PrO xIt not only has good chemical compatibility with the BCFZY-GDC composite material, but also significantly accelerates the oxygen ion exchange performance of the cathode material, especially under lower temperature conditions. For example, at a working temperature of 600 °C, the R p value of the composite cathode can reach about 0.082 Ω·cm 2 , which is only 25.3% of the composite cathode without PrO x . Its power density can also reach about twice that of the single cell without PrO x , which is almost the highest value of the Ni-YSZ anode-supported single cells on the market. These results indicate that in the lower temperature range, the impregnation of PrO x nanoparticles is an effective method to improve the oxygen ion exchange performance of the cathode ORR process. Therefore, this will be a very promising method for preparing high-activity SOFCs cathode materials.

[0113] It should be understood that the application of the present invention is not limited to the above examples. For those of ordinary skill in the art, improvements or transformations can be made according to the above description, and all such improvements and transformations should fall within the protection scope of the appended claims of the present invention.

Claims

1. A cathode electrocatalyst for a solid oxide fuel cell, characterized in that, The material of the cathode electrocatalyst of the solid oxide fuel cell is BCFZY-GDC-PrO x , where BCFZY is BaCo 0.4 Fe 0.4 Zr 0.1 Y 0.1 O 3-δ , GDC is Ce 0.8 Gd 0.2 O 1.9 ; The preparation method of the solid oxide fuel cell cathode electrocatalyst includes the steps of: Weigh 1.800 g of BCFZY, 201.200 g of GDC and 1.579 g of PEG and add them into a polytetrafluoroethylene tank. Add zirconium balls and ethanol thereto, and then carry out ball milling treatment to obtain a BCFZY-GDC composite cathode slurry; Adopt the screen printing method to coat the BCFZY-GDC composite cathode slurry on the surface of the half cell or the electrolyte surface, and place it in a muffle furnace for the first calcination treatment to obtain a BCFZY-GDC composite cathode coating; The 0.3M Pr(NO3)3▪6H2O solution was dropped onto the surface of the BCFZY-GDC composite cathode coating, and the titrated solution volumes were 20 μl / cm 2 , 40 μl / cm 2 , 60 μl / cm 2 and 80 μl / cm 2 ; then it was placed in a muffle furnace for the second calcination treatment to obtain the solid oxide fuel cell cathode electrocatalyst; The preparation method of the BCFZY includes: Measure 45 mL of nitric acid into a beaker containing 400 ml of deionized water. Add 10.5066 g of Ba(NO3)2, 4.7047 g of Co(NO3)2·6H2O, 6.4708 g of Fe(NO3)3·9H2O, 1.7346 g of Zr(NO3)4·5H2O, 1.5343 g of Y(NO3)3·6H2O, 30.8946 g of citric acid, and 23.4973 g of EDTA into the beaker in sequence. Stir for 20 minutes, then adjust the pH value to 7.2 with ammonia water. Subsequently, continue stirring for 4 h, heat to 150 °C to evaporate the water. When there is 150 mL of solution left in the beaker, transfer this solution to an evaporating dish and continue to evaporate the solution to dryness to obtain a powder. Then place the powder at 950 °C for 300 minutes to obtain the BCFZY.

2. The cathode electrocatalyst of the solid oxide fuel cell according to claim 1, characterized in that The temperature of the first calcination treatment is 900 - 100 °C, and the time is 4 - 6 h.

3. The cathode electrocatalyst for a solid oxide fuel cell according to claim 1, wherein The temperature of the second calcination treatment is 750 - 850 °C, and the time is 1 - 3 h.

4. The cathode electrocatalyst of the solid oxide fuel cell according to claim 1, wherein The step of weighing 1.800 g of BCFZY, 201.200 g of GDC and 1.579 g of PEG and adding them into a polytetrafluoroethylene tank, adding zirconium balls and ethanol thereto, and then carrying out ball milling treatment to obtain a BCFZY-GDC composite cathode slurry includes: Weigh 1.800 g of BCFZY, 201.200 g of GDC and 1.579 g of PEG and add them into a polytetrafluoroethylene tank. Add zirconium balls and ethanol thereto, seal it with transparent tape, then place it in a quartz boat and put it into a ball mill for ball milling treatment; After the ball milling is completed, take it out, sieve it, and dry it in an oven at 50 - 80 °C. Then grind it again for 10 - 30 min, and collect the BCFZY-GDC composite cathode slurry.

5. The cathode electrocatalyst for a solid oxide fuel cell according to claim 4, wherein The speed of the ball milling treatment is 100 - 150 r / min, and the ball milling time is 20 - 28 h.

6. Use of the cathode electrocatalyst of the solid oxide fuel cell as described in claim 1, characterized in that, Use the solid oxide fuel cell cathode electrocatalyst to prepare a solid oxide fuel cell.

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