Layered structure solid oxide fuel cell composite cathode catalyst and preparation method and application thereof

Abstract

The invention discloses a layered structure solid oxide fuel cell composite cathode catalyst as well as a preparation method and application thereof, and belongs to the field of solid oxide fuel cells. The invention aims to solve the problem that the electro-catalytic performance and low-oxygen reduction reaction activation energy of the existing medium-temperature solid oxide fuel cell are poor. The Sr2. 9Ca0. 1Fe2O7-CuO composite cathode catalyst is prepared by adopting a sol-gel method and a solid phase method, the components in a sol-gel system are in a nanometer range, the reaction is easier to carry out, the reaction temperature is low, the prepared materials are uniformly mixed, and the sol-gel method is carried out in a solution, so that even if the content of doped elements is very low, the doping can be easily realized; the material is prepared by adopting a solid phase method, and the method has the advantages of convenience in operation, simple synthesis process, uniform particle size, no agglomeration of powder particles, good filling property, low cost, high yield and the like, so that the electrochemical performance of the cathode catalyst is improved, and the method is convenient to operate and suitable for industrial production.

Description

Technical Field

[0001] The present invention belongs to the field of solid oxide fuel cells. Background Art

[0002] Solid oxide fuel cell (SOFC) is an energy conversion device that directly converts the chemical energy of fuel into electrical energy. It not only has the advantages of high power generation efficiency, strong fuel adaptability, and high-temperature waste heat recovery, but also has the following outstanding advantages: (1) Wide range of fuel applications. SOFC can directly use hydrogen as fuel gas, or use coal gas, natural gas and other fuels. (2) All-solid-state structure. The three components of SOFC. The anode, cathode and electrolyte are all solid, so there is no corrosion problem like acid-base electrolyte and molten salt electrolyte. (3) Long service life. The current service life of SOFC is 40,000 to 80,000 hours. However, traditional SOFC operates in the high temperature range of 800℃ to 1000℃, which will lead to material degradation and poor compatibility between the components in the battery. Therefore, people have been working to reduce its temperature to the medium temperature range (500℃-700℃). However, during the operation, the ORR catalytic activity and output performance on the cathode also deteriorate, which hinders the application of solid oxide fuel cells. Therefore, it is currently necessary to explore solid oxide fuel cell catalysts with better catalytic activity. Summary of the Invention

[0003] The purpose of the present invention is to solve the problem of poor electrocatalytic performance and low oxygen reduction reaction activation energy of existing medium-temperature solid oxide fuel cells, and to provide a layered structure solid oxide fuel cell composite cathode catalyst and its preparation method and application.

[0004] A layered solid oxide fuel cell composite cathode catalyst composed of Sr 2.9 Ca 0.1 Fe2O7 and CuO, among which Sr 2.9 Ca 0.1 The mass fraction of Fe2O7 is 90% to 97%, and the mass fraction of CuO is 3% to 10%.

[0005] A method for preparing a composite cathode catalyst for a layered solid oxide fuel cell is specifically completed by the following steps:

[0006] 1. Based on the chemical formula Sr 2.9 Ca 0.1Fe2O7, weigh Sr(NO3)2, Ca(NO3)2·4H2O and Fe(NO3)3·9H2O according to the stoichiometric ratio and dissolve them in deionized water, heat and stir until uniform, then add citric acid and EDTA, heat and stir until completely dissolved, and then adjust the pH value of the solution to 7-8 to obtain a transparent solution;

[0007] 2. First, heat and stir the transparent solution until it becomes a viscous colloid to obtain a dry gel; then dry the dry gel to obtain a precursor powder; finally, calcine the precursor powder to obtain Sr 2.9 Ca 0.1 Fe2O7 catalyst;

[0008] 3. Weigh Sr according to a certain mass ratio 2.9 Ca 0.1 The Fe2O7 catalyst and CuO powder are then added to anhydrous ethanol, fully mixed, and then ground in an agate mortar for a period of time to obtain a mixed powder; the mixed powder is calcined to obtain a layered structure solid oxide fuel cell composite cathode catalyst.

[0009] A layered structure solid oxide fuel cell composite cathode catalyst is used for preparing a solid oxide fuel cell composite cathode catalyst symmetrical cell or a three-electrode cell.

[0010] Beneficial effects of the present invention:

[0011] 1. The present invention adopts sol-gel method and solid phase method to prepare Sr 2.9 Ca 0.1 The Fe2O7-CuO composite cathode catalyst has components in the nanometer range in the sol-gel system, making the reaction easier to carry out, the reaction temperature is low, and the prepared materials are evenly mixed. The sol-gel method is carried out in solution, so even if the content of the doping element is very small, doping can be easily achieved. The present invention uses a solid-phase method to prepare the material, which has the advantages of convenient operation, simple synthesis process, uniform particle size, no agglomeration of powder particles, good filling properties, low cost, and high yield, thereby improving the electrochemical performance of the cathode catalyst.

[0012] 2. Sr prepared by the present invention 2.9 Ca 0.1 The symmetrical battery prepared by Fe2O7-CuO composite cathode catalyst has good high temperature chemical stability and electrocatalytic performance at 500℃~700℃. 2.9 Ca 0.1 The polarization resistance of the symmetrical cell prepared by Fe2O7-3% CuO in air at 700℃ is 0.17Ωcm 2 , the activation energy is 118.48 kJmol -1 , and using 95% Sr 2.9 Ca0.1 The polarization resistance of the symmetrical cell prepared by Fe2O7-5%CuO in air at 700℃ is 0.14Ωcm 2 , the activation energy is 115.86 kJ mol -1 ;

[0013] 3. The method of the present invention is simple, easy to operate and suitable for industrial production.

[0014] The present invention can obtain a layered structure solid oxide fuel cell composite cathode catalyst Sr 2.9 Ca 0.1 Fe2O7—Cu O. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 97% Sr prepared in Example 1 2.9 Ca 0.1 X-ray diffraction pattern of Fe2O7-3%CuO composite cathode catalyst;

[0016] Figure 2 This is the AC impedance spectrum tested at 700℃ in air, where The Sr prepared in Example 1 is shown in FIG. 2.9 Ca 0.1 Fe2O7 symmetrical battery, as shown in the figure Indicates the 97% Sr prepared in Example 1 2.9 Ca 0.1 Fe2O7-3%CuO symmetrical battery, The 95% Sr prepared in Example 2 is shown 2.9 Ca 0.1 Fe2O7-5% CuO symmetrical cell;

[0017] Figure 3 is the Arrhenius curve diagram, where - The Sr prepared in Example 1 is shown in FIG. 2.9 Ca 0.1 Fe2O7 symmetrical battery, in the figure - - indicates the 97% Sr prepared in Example 1 2.9 Ca 0.1 Fe2O7-3%CuO symmetrical cell, - - indicates the 95% Sr prepared in Example 2 2.9 Ca 0.1 Fe2O7-5%CuO symmetrical cell;

[0018] Figure 4 Sr 2.9 Ca 0.1 Fe2O7 and Sr 2.9 Ca0.1 The Tafel curve of the Fe2O7-CuO three-electrode battery at 600-700℃, (a) is the Sr prepared in Example 2 2.9 Ca 0.1 Fe2O7 three-electrode battery; (b) 97% Sr prepared in Example 3 2.9 Ca 0.1 Fe2O7-3%CuO three-electrode battery; (c) 95% Sr prepared in Example 4 2.9 Ca 0.1 Fe2O7-5%CuO three-electrode battery;

[0019] Figure 5 Sr 2.9 Ca 0.1 Fe2O7 and Sr 2.9 Ca 0.1 Polarization curves of Fe2O7-CuO composite cathode catalyst in SOFC mode at 600-700℃, (a) is the Sr prepared in Example 2 2.9 Ca 0.1 Fe2O7 three-electrode battery; (b) 97% Sr prepared in Example 3 2.9 Ca 0.1 Fe2O7-3%CuO three-electrode battery; (c) 95% Sr prepared in Example 4 2.9 Ca 0.1 Fe2O7-5%CuO three-electrode battery. DETAILED DESCRIPTION

[0020] Specific embodiment 1: This embodiment is a layered structure solid oxide fuel cell composite cathode catalyst composed of Sr 2.9 Ca 0.1 Fe2O7 and CuO, among which Sr 2.9 Ca 0.1 The mass fraction of Fe2O7 is 90% to 97%, and the mass fraction of CuO is 3% to 10%.

[0021] Specific embodiment 2: The difference between this embodiment and specific embodiment 1 is that the composite cathode catalyst is composed of Sr 2.9 Ca 0.1 Fe2O7 and CuO, among which Sr 2.9 Ca 0.1 The mass fraction of Fe2O7 is 90% to 95%, and the mass fraction of CuO is 5% to 10%. The other steps are the same as those in the first embodiment.

[0022] Specific embodiment 3: The difference between this embodiment and specific embodiment 1 or 2 is that: first, Sr is prepared by sol-gel method.2.9 Ca 0.1 Fe2O7 is then compounded with CuO to obtain a layered structure solid oxide fuel cell composite cathode catalyst. The other steps are the same as those in the first or second embodiment.

[0023] Specific embodiment 4: This embodiment differs from specific embodiments 1 to 3 in that: a method for preparing a composite cathode catalyst for a layered solid oxide fuel cell is specifically completed by the following steps:

[0024] 1. Based on the chemical formula Sr 2.9 Ca 0.1 Fe2O7, weigh Sr(NO3)2, Ca(NO3)2·4H2O and Fe(NO3)3·9H2O according to the stoichiometric ratio and dissolve them in deionized water, heat and stir until uniform, then add citric acid and EDTA, heat and stir until completely dissolved, and then adjust the pH value of the solution to 7-8 to obtain a transparent solution;

[0025] 2. First, heat and stir the transparent solution until it becomes a viscous colloid to obtain a dry gel; then dry the dry gel to obtain a precursor powder; finally, calcine the precursor powder to obtain Sr 2.9 Ca 0.1 Fe2O7 catalyst;

[0026] 3. Weigh Sr according to a certain mass ratio 2.9 Ca 0.1 The Fe2O7 catalyst and CuO powder are then added to anhydrous ethanol, thoroughly mixed, and ground in an agate mortar for a period of time to obtain a mixed powder. The mixed powder is then calcined to obtain a layered solid oxide fuel cell composite cathode catalyst. The remaining steps are the same as those in Specific Embodiments 1 to 3.

[0027] Specific embodiment 5: This embodiment differs from specific embodiments 1 to 4 in that: the mass ratio of Sr(NO3)2 described in step 1 to deionized water is 1.84g:100mL; the mass ratio of Ca(NO3)2·4H2O described in step 1 to deionized water is 0.07g:100mL; the mass ratio of Fe(NO3)3·9H2O described in step 1 to deionized water is 2.42g:100mL; the mass ratio of citric acid described in step 1 to deionized water is (6g-6.5g):100mL; the mass ratio of EDTA described in step 1 to deionized water is (4g-5g):100mL; the temperature of heating and stirring described in step 1 is 60℃-80℃; and in step 1, the pH value of the solution is adjusted to 7-8 using ammonia water with a mass fraction of 20%-25%. The other steps are the same as specific embodiments 1 to 4.

[0028] Specific embodiment 6: The difference between this embodiment and specific embodiments 1 to 5 is that: in step 2, the transparent solution is heated and stirred at 60°C to 80°C with stirring until it becomes a viscous colloid to obtain a dry gel; in step 2, the dry gel is dried at 180°C for 6h to 8h to obtain a precursor powder; in step 2, the precursor powder is placed in a high-temperature furnace at a temperature of 900°C to 1100°C and calcined for 8h to 12h to obtain Sr 2.9 Ca 0.1 Fe2O7 catalyst. Other steps are the same as those in the first to fifth embodiments.

[0029] Specific embodiment 7: This embodiment differs from specific embodiments 1 to 6 in that: in step 3, Sr 2.9 Ca 0.1 The volume ratio of the total mass of the Fe2O7 catalyst and CuO powder to anhydrous ethanol is (0.3g-0.4g):(16mL-18mL); the grinding time in step 3 is 30min-60min; and in step 3, the mixed powder is calcined in a high-temperature furnace at 800°C-900°C for 4h-6h. The other steps are the same as those in specific embodiments 1 to 6.

[0030] Specific embodiment 8: This embodiment differs from specific embodiments 1 to 7 in that a layered solid oxide fuel cell composite cathode catalyst is used to prepare a solid oxide fuel cell composite cathode catalyst symmetrical cell or a three-electrode cell. The other steps are the same as specific embodiments 1 to 7.

[0031] Specific embodiment 9: This embodiment differs from specific embodiments 1 to 8 in that the method for preparing the solid oxide fuel cell composite cathode catalyst symmetrical cell is specifically completed according to the following steps:

[0032] The layered solid oxide fuel cell composite cathode catalyst was ground in an agate mortar, and then ethyl cellulose and terpineol were added and ground continuously to obtain a uniformly mixed electrode slurry; the uniformly mixed electrode slurry was evenly applied on the Ce 0.9 Gd 0.1 O 1.95 The two sides of the solid electrolyte are then placed in an oven for drying and finally sintered in a muffle furnace to obtain a solid oxide fuel cell Sr 2.9 Ca 0.1 Symmetrical cell with Fe2O7-CuO composite cathode catalyst;

[0033] The grinding time is 20min to 40min;

[0034] The mass ratio of the layered solid oxide fuel cell composite cathode catalyst to the volume ratio of terpineol is 0.1 g: (0.05 mL to 0.1 mL);

[0035] The mass ratio of the ethyl cellulose to the terpineol is 5:95;

[0036] The sintering temperature is 950° C. to 1000° C., and the sintering time is 3 to 4 hours. The other steps are the same as those in the first to eighth embodiments.

[0037] Specific embodiment 10: This embodiment differs from specific embodiments 1 to 9 in that the preparation method of the solid oxide fuel cell composite cathode catalyst three-electrode cell is specifically completed according to the following steps:

[0038] The layered solid oxide fuel cell composite cathode catalyst was ground in an agate mortar, and then ethyl cellulose and terpineol were added and ground continuously to obtain a uniformly mixed electrode slurry; the uniformly mixed electrode slurry was evenly applied on the Ce 0.9 Gd 0.1 O 1.95 The solid electrolyte side is then placed in an oven for drying and finally placed in a muffle furnace for sintering to obtain the working electrode of the solid oxide fuel cell composite cathode catalyst three-electrode cell; on the Ce 0.9 Gd 0.1 O 1.95 A silver paste coating is applied symmetrically on the other side of the solid electrolyte to serve as a counter electrode. A conductive silver wire is connected to the same side of the working electrode to serve as a reference electrode. The gap between the working electrode and the reference electrode is greater than three times the thickness of the electrolyte, and a solid oxide fuel cell composite cathode catalyst three-electrode cell is assembled.

[0039] The grinding time is 20min to 40min;

[0040] The mass ratio of the layered solid oxide fuel cell composite cathode catalyst to the volume ratio of terpineol is 0.1 g: (0.05 mL to 0.1 mL);

[0041] The mass ratio of the ethyl cellulose to the terpineol is 5:95;

[0042] The sintering temperature is 950° C. to 1000° C., and the sintering time is 3 to 4 hours. The other steps are the same as those in the first to ninth embodiments.

[0043] The following examples are used to verify the beneficial effects of the present invention:

[0044] Example 1: A method for preparing a composite cathode catalyst for a layered solid oxide fuel cell is specifically completed by the following steps:

[0045] 1. Based on the chemical formula Sr 2.9 Ca 0.1 Fe2O7, 1.84 g Sr(NO3)2, 0.07 g Ca(NO3)2·4H2O and 2.42 g Fe(NO3)3·9H2O were weighed according to the stoichiometric ratio and dissolved in 100 mL deionized water. The mixture was heated at 80°C and stirred until uniformly dissolved. Then, 6.30 g citric acid and 4.38 g EDTA were added and heated at 80°C and stirred until completely dissolved. The pH value of the solution was then adjusted to 7.5 with 20% ammonia water to obtain a transparent solution.

[0046] 2. Heat and stir the transparent solution at 80°C until it becomes a viscous colloid to obtain a dry gel; then dry the dry gel at 180°C for 6 hours to obtain a precursor powder; finally, calcine the precursor powder in a high-temperature furnace at 1100°C for 12 hours to obtain Sr 2.9 Ca 0.1 Fe2O7 catalyst;

[0047] 3. Weigh Sr according to a certain mass ratio 2.9 Ca 0.1 Fe2O7 catalyst and CuO powder were then added to anhydrous ethanol, mixed thoroughly, and ground in an agate mortar for 30 minutes to obtain a mixed powder; the mixed powder was calcined at 800 ° C for 6 hours to obtain a layered structure solid oxide fuel cell 97% Sr 2.9 Ca 0.1 Fe2O7-3%CuO composite cathode catalyst;

[0048] In step 3, Sr 2.9 Ca 0.1 The volume ratio of the total mass of Fe2O7 catalyst and CuO powder to anhydrous ethanol was 0.3 g:16 mL;

[0049] The layered solid oxide fuel cell 97% Sr in step 3 2.9 Ca 0.1 Sr in Fe2O7-3%CuO composite cathode catalyst 2.9 Ca 0.1 The mass fraction of Fe2O7 is 97%, and the mass fraction of CuO is 3%.

[0050] Example 2: The difference between this example and example 1 is that in step 3, Sr is weighed according to a certain mass ratio. 2.9 Ca 0.1Fe2O7 catalyst and CuO powder were then added to anhydrous ethanol, mixed thoroughly, and ground in an agate mortar for 30 minutes to obtain a mixed powder; the mixed powder was calcined at 800 ° C for 6 hours to obtain a layered structure solid oxide fuel cell 95% Sr 2.9 Ca 0.1 Fe2O7-5%CuO composite cathode catalyst; the layered solid oxide fuel cell 95% Sr 2.9 Ca 0.1 Sr in Fe2O7-5%CuO composite cathode catalyst 2.9 Ca 0.1 The mass fraction of Fe2O7 is 95%, and the mass fraction of CuO is 5%. Other steps and parameters are the same as those in Example 1.

[0051] Application Example 1: Layered structure solid oxide fuel cell 97% Sr prepared in Example 1 2.9 Ca 0.1 The Fe2O7-3%CuO composite cathode catalyst is used to prepare a symmetrical cell, which is completed in the following steps:

[0052] 0.1 g of the layered solid oxide fuel cell 97% Sr prepared in Example 1 was added 2.9 Ca 0.1 The Fe2O7-3% CuO composite cathode catalyst was ground in an agate mortar, and then ethyl cellulose and 0.05 mL of terpineol were added and ground for 30 min to obtain a uniformly mixed electrode slurry. The uniformly mixed electrode slurry was evenly applied on the Ce 0.9 Gd 0.1 O 1.95 The two sides of the solid electrolyte were then placed in an oven for drying and finally sintered in a muffle furnace at 950 ° C for 4 hours to obtain 97% Sr 2.9 Ca 0.1 Fe2O7-3%CuO symmetrical cell;

[0053] The mass ratio of the ethyl cellulose to the terpineol is 5:95.

[0054] Application Example 2: Layered structure solid oxide fuel cell 95% Sr prepared in Example 2 2.9 Ca 0.1 The Fe2O7-5%CuO composite cathode catalyst is used to prepare a symmetrical cell, which is completed in the following steps:

[0055] 0.1 g of the layered solid oxide fuel cell 95% Sr prepared in Example 2 was added 2.9 Ca 0.1The Fe2O7-5% CuO composite cathode catalyst was ground in an agate mortar, and then ethyl cellulose and 0.05 mL of terpineol were added and ground for 30 min to obtain a uniformly mixed electrode slurry. The uniformly mixed electrode slurry was evenly applied on the Ce 0.9 Gd 0.1 O 1.95 The two sides of the solid electrolyte were then placed in an oven for drying and finally placed in a muffle furnace at 950°C for 4 hours to obtain the 95% Sr prepared in Example 2. 2.9 Ca 0.1 Fe2O7-5% CuO symmetrical cell;

[0056] The mass ratio of the ethyl cellulose to the terpineol is 5:95.

[0057] Comparative Example 1: Sr 2.9 Ca 0.1 Fe2O7 catalyst is used to prepare symmetrical cells, which is completed in the following steps:

[0058] 0.1gSr 2.9 Ca 0.1 The Fe2O7 catalyst was ground in an agate mortar, and then ethyl cellulose and 0.05 mL of terpineol were added and ground for 30 min to obtain a uniformly mixed electrode slurry. The uniformly mixed electrode slurry was evenly applied on the Ce 0.9 Gd 0.1 O 1.95 The two sides of the solid electrolyte were then placed in an oven for drying and finally sintered in a muffle furnace at 950 ° C for 4 h to obtain Sr 2.9 Ca 0.1 Fe2O7 symmetrical cell;

[0059] The mass ratio of the ethyl cellulose to the terpineol is 5:95.

[0060] Figure 1 97% Sr prepared in Example 1 2.9 Ca 0.1 X-ray diffraction pattern of Fe2O7-3%CuO composite cathode catalyst;

[0061] from Figure 1 It can be seen that the 97% Sr prepared in Example 1 2.9 Ca 0.1 The X-ray diffraction pattern of Fe2O7-3%CuO composite cathode catalyst is shown in Figure 2. 2.9 Ca 0.1 No third phase was detected in the Fe2O7-3%CuO composite cathode catalyst. 2.9 Ca 0.1The XRD diffraction peaks of Fe2O7 and CuO do not move after the composite, indicating that under working conditions, Sr 2.9 Ca 0.1 Fe2O7 and CuO have good compatibility.

[0062] Figure 2 This is the AC impedance spectrum tested at 700℃ in air, where The Sr prepared in Example 1 is shown in FIG. 2.9 Ca 0.1 Fe2O7 symmetrical battery, as shown in the figure Indicates the 97% Sr prepared in Example 1 2.9 Ca 0.1 Fe2O7-3%CuO symmetrical battery,

[0063] Indicates the 95% Sr prepared by Example 2 2.9 Ca 0.1 Fe2O7-5% CuO symmetrical cell;

[0064] The test results show that the 97% Sr prepared in Example 1 2.9 Ca 0.1 The polarization impedance of the symmetrical cell prepared by Fe2O7-3%CuO composite cathode catalyst is 0.17Ωcm 2 , using the 95% Sr prepared in Example 2 2.9 Ca 0.1 The polarization impedance of the symmetrical cell prepared with Fe2O7-5%CuO composite cathode catalyst is 0.14Ωcm 2 , this result is Sr 2.9 Ca 0.1 Approximately one-third of the Fe2O7 symmetrical cell (0.39Ωcm at the same test temperature) 2 ),See Figure 2 The Sr prepared by the present invention is described 2.9 Ca 0.1 The composite cathode catalyst of Fe2O7-CuO can improve the electrochemical performance of the cathode.

[0065] Figure 3 is the Arrhenius curve diagram, where - The Sr prepared in Example 1 is shown in FIG. 2.9 Ca 0.1 Fe2O7 symmetrical battery, in the figure - - indicates the 97% Sr prepared in Example 1 2.9 Ca 0.1 Fe2O7-3%CuO symmetrical cell, - - indicates the 95% Sr prepared in Example 22.9 Ca 0.1 Fe2O7-5%CuO symmetrical cell;

[0066] The test results show that the 97% Sr prepared in Example 1 2.9 Ca 0.1 The activation energy of the symmetrical cell prepared with Fe2O7-3%CuO composite cathode catalyst is 118.48 kJ mol -1 , using the 95% Sr prepared in Example 2 2.9 Ca 0.1 The activation energy of the symmetrical cell prepared with Fe2O7-5%CuO composite cathode catalyst is 115.86 kJ mol -1 , which is lower than Sr 2.9 Ca 0.1 The activation energy of the Fe2O7 symmetric cell is 138.1 kJ mol -1 The activation energy of the electrode is significantly reduced, indicating that the electrocatalytic performance of the oxygen reduction reaction is enhanced.

[0067] Application Example 3: Layered solid oxide fuel cell 97% Sr prepared in Example 1 2.9 Ca 0.1 The Fe2O7-3%CuO composite cathode catalyst is used to prepare a three-electrode battery, which is completed in the following steps:

[0068] 0.1 g of the layered solid oxide fuel cell 97% Sr prepared in Example 1 was added 2.9 Ca 0.1 The Fe2O7-3% CuO composite cathode catalyst was ground in an agate mortar, and then ethyl cellulose and 0.05 mL of terpineol were added and ground for 30 min to obtain a uniformly mixed electrode slurry. The uniformly mixed electrode slurry was evenly applied on the Ce 0.9 Gd 0.1 O 1.95 On one side of the solid electrolyte, it is then placed in an oven for drying and finally sintered in a muffle furnace at 950°C for 4 hours to obtain the working electrode of the solid oxide fuel cell composite cathode catalyst three-electrode battery; a silver paste coating is brushed on the symmetrical position of the other side as the counter electrode; a conductive silver wire is connected to the same side of the working electrode as the reference electrode; the gap between the working electrode and the reference electrode is greater than three times the thickness of the electrolyte, and 97% Sr is assembled. 2.9 Ca 0.1 Fe2O7-3%CuO three-electrode battery;

[0069] The mass ratio of the ethyl cellulose to the terpineol is 5:95.

[0070] Application Example 4: Layered solid oxide fuel cell 95% Sr prepared in Example 2 2.9 Ca 0.1 The Fe2O7-5%CuO composite cathode catalyst is used to prepare a three-electrode battery, which is completed in the following steps:

[0071] 0.1 g of the layered solid oxide fuel cell 95% Sr prepared in Example 2 was added 2.9 Ca 0.1 The Fe2O7-5% CuO composite cathode catalyst was ground in an agate mortar, and then ethyl cellulose and 0.05 mL of terpineol were added and ground for 30 min to obtain a uniformly mixed electrode slurry. The uniformly mixed electrode slurry was evenly applied on the Ce 0.9 Gd 0.1 O 1.95 On one side of the solid electrolyte, it is then placed in an oven for drying and finally placed in a muffle furnace at 950°C for 4 hours to obtain the working electrode of the solid oxide fuel cell composite cathode catalyst three-electrode battery; a silver paste coating is brushed on the symmetrical position of the other side as the counter electrode; a conductive silver wire is connected to the same side of the working electrode as the reference electrode; the gap between the working electrode and the reference electrode is greater than three times the thickness of the electrolyte, and 95% Sr is assembled. 2.9 Ca 0.1 Fe2O7-5%CuO three-electrode battery;

[0072] The mass ratio of the ethyl cellulose to the terpineol is 5:95.

[0073] Comparative Example 2: Sr 2.9 Ca 0.1 The Fe2O7 catalyst is used to prepare a three-electrode battery, which is completed in the following steps:

[0074] 0.1g Sr 2.9 Ca 0.1 The Fe2O7 catalyst was ground in an agate mortar, and then ethyl cellulose and 0.05 mL of terpineol were added and ground for 30 min to obtain a uniformly mixed electrode slurry. The uniformly mixed electrode slurry was evenly applied on the Ce 0.9 Gd 0.1 O 1.95 On one side of the solid electrolyte, it is then placed in an oven for drying and finally placed in a muffle furnace at 950°C for 4 hours to obtain the working electrode of the solid oxide fuel cell composite cathode catalyst three-electrode battery; a silver paste coating is brushed on the symmetrical position of the other side as the counter electrode; a conductive silver wire is connected to the same side of the working electrode as the reference electrode; the gap between the working electrode and the reference electrode is greater than three times the thickness of the electrolyte, and the Sr 2.9 Ca 0.1 Fe2O7 three-electrode battery;

[0075] The mass ratio of the ethyl cellulose to the terpineol is 5:95.

[0076] Figure 4 Sr 2.9 Ca 0.1 Fe2O7 and Sr 2.9 Ca 0.1 The Tafel curve of the Fe2O7-CuO three-electrode battery at 600-700℃, (a) is the Sr prepared in Example 2 2.9 Ca 0.1 Fe2O7 three-electrode battery; (b) 97% Sr prepared in Example 3 2.9 Ca 0.1 Fe2O7-3%CuO three-electrode battery; (c) 95% Sr prepared in Example 4 2.9 Ca 0.1 Fe2O7-5%CuO three-electrode battery;

[0077] The test results show that the exchange current density (i0) is a key factor in measuring the electrochemical activity of the electrode. 2.9 Ca 0.1 Compared with Fe2O7 electrode, 97% Sr 2.9 Ca 0.1 Fe2O7—3% CuO and 95% Sr 2.9 Ca 0.1 Fe2O7-5% CuO shows a higher i0 value at 600-700℃. The larger the i0 value, the faster the ORR kinetics of the electrode. 2.9 Ca 0.1 Fe2O7-CuO composite cathode catalyst has significant advantages in electrochemical performance.

[0078] Figure 5 Sr 2.9 Ca 0.1 Fe2O7 and Sr 2.9 Ca 0.1 Polarization curves of Fe2O7-CuO composite cathode catalyst in SOFC mode at 600-700℃, (a) is the Sr prepared in Example 2 2.9 Ca 0.1 Fe2O7 three-electrode battery; (b) 97% Sr prepared in Example 3 2.9 Ca 0.1 Fe2O7-3%CuO three-electrode battery; (c) 95% Sr prepared in Example 4 2.9 Ca 0.1 Fe2O7-5%CuO three-electrode battery.

[0079] The test results show that at 700℃, SOFC mode, Sr 2.9 Ca 0.1 The current density of Fe2O7 is -16.01 mA cm -2 , the cathode overpotential is -76.48mV. 97% Sr 2.9 Ca 0.1 The current density of Fe2O7-3%CuO is -66.34 mA cm -2 , the cathode overpotential is -30.41mV. 95% Sr 2.9 Ca 0.1 The current density of Fe2O7-5%CuO is -85.12 mA cm -2 , the cathode overpotential is -44.44mV. Sr 2.9 Ca 0.1 Fe2O7-CuO electrode and Sr 2.9 Ca 0.1 The Fe2O7 electrode shows a larger current density at the same overpotential. 2.9 Ca 0.1 Fe2O7-CuO has potential advantages in improving electrocatalytic activity. The results show that Sr 2.9 Ca 0.1 The Fe2O7-CuO composite cathode catalyst exhibits good catalytic activity in SOFC mode.

Claims

1. A composite cathode catalyst for a layered solid oxide fuel cell, characterized in that The composite cathode catalyst is composed of Sr 2.9 Ca 0.1 Fe2O7 and CuO, among which Sr 2.9 Ca 0.1 The mass fraction of Fe2O7 is 90% to 97%, and the mass fraction of CuO is 3% to 10%.

2. A layered solid oxide fuel cell composite cathode catalyst according to claim 1, characterized in that The composite cathode catalyst is composed of Sr 2.9 Ca 0.1 Fe2O7 and CuO, among which Sr 2.9 Ca 0.1 The mass fraction of Fe2O7 is 90% to 95%, and the mass fraction of CuO is 5% to 10%.

3. The method for preparing a composite cathode catalyst for a layered solid oxide fuel cell according to claim 1, wherein First, Sr was prepared by sol-gel method. 2.9 Ca 0.1 Fe2O7, and then compounded with CuO to obtain a layered structure solid oxide fuel cell composite cathode catalyst.

4. The method for preparing a composite cathode catalyst for a layered solid oxide fuel cell according to claim 1, wherein The method for preparing the layered solid oxide fuel cell composite cathode catalyst is specifically completed by the following steps:

1. Based on the chemical formula Sr 2.9 Ca 0.1 Fe2O7, weigh Sr(NO3)2, Ca(NO3)2·4H2O and Fe(NO3)3·9H2O according to the stoichiometric ratio and dissolve them in deionized water, heat and stir until uniform, then add citric acid and EDTA, heat and stir until completely dissolved, and then adjust the pH value of the solution to 7-8 to obtain a transparent solution; 2. First, heat and stir the transparent solution until it becomes a viscous colloid to obtain a dry gel; then dry the dry gel to obtain a precursor powder; finally, calcine the precursor powder to obtain Sr 2.9 Ca 0.1 Fe2O7 catalyst; 3. Weigh Sr according to a certain mass ratio 2.9 Ca 0.1 The Fe2O7 catalyst and CuO powder are then added to anhydrous ethanol, fully mixed, and then ground in an agate mortar for a period of time to obtain a mixed powder; the mixed powder is calcined to obtain a layered structure solid oxide fuel cell composite cathode catalyst.

5. The method for preparing a composite cathode catalyst for a layered solid oxide fuel cell according to claim 1, characterized in that The mass ratio of Sr(NO3)2 described in step one to deionized water is 1.84g:100mL; the mass ratio of Ca(NO3)2·4H2O described in step one to deionized water is 0.07g:100mL; the mass ratio of Fe(NO3)3·9H2O described in step one to deionized water is 2.42g:100mL; the mass ratio of citric acid described in step one to deionized water is (6g~6.5g):100mL; the mass ratio of EDTA described in step one to deionized water is (4g~5g):100mL; the temperature of heating and stirring described in step one is 60℃~80℃; in step one, the pH value of the solution is adjusted to 7~8 using ammonia water with a mass fraction of 20%~25%.

6. The method for preparing a composite cathode catalyst for a layered solid oxide fuel cell according to claim 1, characterized in that In step 2, the transparent solution is heated and stirred at 60°C to 80°C until it becomes a viscous colloid to obtain a dry gel; in step 2, the dry gel is dried at 180°C for 6h to 8h to obtain a precursor powder; in step 3, the precursor powder is placed in a high-temperature furnace at a temperature of 900°C to 1100°C and calcined for 8h to 12h to obtain Sr 2.9 Ca 0.1 Fe2O7 catalyst.

7. The method for preparing a composite cathode catalyst for a layered solid oxide fuel cell according to claim 1, characterized in that In step 3, Sr 2.9 Ca 0.1 The volume ratio of the total mass of Fe2O7 catalyst and CuO powder to anhydrous ethanol is (0.3g~0.4g):(16mL~18mL); the grinding time described in step three is 30min~60min; in step three, the mixed powder is placed in a high-temperature furnace at a temperature of 800℃~900℃ and calcined for 4h~6h.

8. The use of a layered solid oxide fuel cell composite cathode catalyst according to claim 1, characterized in that A layered structure solid oxide fuel cell composite cathode catalyst is used for preparing a solid oxide fuel cell composite cathode catalyst symmetrical cell or a three-electrode cell.

9. The use of a layered solid oxide fuel cell composite cathode catalyst according to claim 1, characterized in that The method for preparing the solid oxide fuel cell composite cathode catalyst symmetrical cell is specifically completed according to the following steps: The layered solid oxide fuel cell composite cathode catalyst was ground in an agate mortar, and then ethyl cellulose and terpineol were added and ground continuously to obtain a uniformly mixed electrode slurry; the uniformly mixed electrode slurry was evenly applied on the Ce 0.9 Gd 0.1 O 1.95 The two sides of the solid electrolyte are then placed in an oven for drying and finally sintered in a muffle furnace to obtain a solid oxide fuel cell Sr 2.9 Ca 0.1 Symmetrical cell with Fe2O7-CuO composite cathode catalyst; The grinding time is 20min to 40min; The mass ratio of the layered solid oxide fuel cell composite cathode catalyst to the volume ratio of terpineol is 0.1 g: (0.05 mL to 0.1 mL); The mass ratio of the ethyl cellulose to the terpineol is 5:95; The sintering temperature is 950° C. to 1000° C., and the sintering time is 3 hours to 4 hours.

10. The use of a layered solid oxide fuel cell composite cathode catalyst according to claim 1, characterized in that The preparation method of the solid oxide fuel cell composite cathode catalyst three-electrode cell is specifically completed according to the following steps: The layered solid oxide fuel cell composite cathode catalyst was ground in an agate mortar, and then ethyl cellulose and terpineol were added and ground continuously to obtain a uniformly mixed electrode slurry; the uniformly mixed electrode slurry was evenly applied on the Ce 0.9 Gd 0.1 O 1.95 The solid electrolyte side is then placed in an oven for drying and finally placed in a muffle furnace for sintering to obtain the working electrode of the solid oxide fuel cell composite cathode catalyst three-electrode cell; on the Ce 0.9 Gd 0.1 O 1.95 A silver paste coating is applied symmetrically on the other side of the solid electrolyte to serve as a counter electrode. A conductive silver wire is connected to the same side of the working electrode to serve as a reference electrode. The gap between the working electrode and the reference electrode is greater than three times the thickness of the electrolyte, and a solid oxide fuel cell composite cathode catalyst three-electrode cell is assembled. The grinding time is 20min to 40min; The mass ratio of the layered solid oxide fuel cell composite cathode catalyst to the volume ratio of terpineol is 0.1 g: (0.05 mL to 0.1 mL); The mass ratio of the ethyl cellulose to the terpineol is 5:95; The sintering temperature is 950° C. to 1000° C., and the sintering time is 3 hours to 4 hours.

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