Cathode material, and preparation method therefor and use thereof

Abstract

A cathode material, and a preparation method therefor and the use thereof. The cathode material comprises a perovskite-type ferrite core and CeO2 nanoparticles covering at least part of the surface of the core, which can make the cathode material have high catalytic activity for oxygen reduction. By replacing Sr with Ca, the drawback of Sr being prone to segregation during high-temperature and long-term operation can be overcome, the problem of Sr reacting with an electrolyte to form a high-resistance third phase can be completely solved, and the tolerance of the cathode material to CO2 in a feed gas can be favorably enhanced. The chemical formula of the cathode material is LaaCa0.4-xCexCobFecO3-δ. By limiting the options for the elements in the cathode material and limiting the proportion of each element to be within a specific range, the cathode material is made to have high catalytic activity for oxygen reduction and structural stability for long-term operation, which thus enhances the electrochemical performance of a battery, and can reduce the overall impedance of the battery and increase the maximum power density of the battery.

Description

A cathode material, its preparation method and application

[0001] This application claims priority to Chinese Patent Application No. 202411035094.6, filed on July 30, 2024, entitled "A cathode material and its preparation method and application", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to solid oxide fuel cell technology, specifically to a cathode material, its preparation method, and its application. Background Technology

[0003] Solid oxide fuel cells (SOFCs) are all-solid-state chemical power generation devices that efficiently and environmentally convert the chemical energy stored in fuel and oxidant into electrical energy directly at medium to high temperatures. The oxygen reduction reaction at the SOFC cathode is the rate-limiting step in the entire electrochemical process, thus requiring high electrocatalytic activity from the cathode material. Currently, perovskite-type oxides... 1-x Sr x Co 1-y Fe y O 3-δ (LSCF) is one of the most ideal cathode materials for medium-temperature SOFCs.

[0004] LSCF materials exhibit excellent oxygen reduction electrocatalytic activity and high conductivity; however, the Sr element at the A-site is prone to segregation during long-term high-temperature operation, reacting with the electrolyte to form a high-resistivity third phase, leading to a significant decline in the battery's electrochemical performance. Against this backdrop, the industry is dedicated to developing cathode materials that combine high activity and stability, such as modified LSCF, composite electrodes, and double perovskite / layered perovskite materials. Modification of LSCF materials typically involves adjusting the proportions of various elements, introducing A-site defects, and doping more elements at the B-site; however, these methods cannot fundamentally solve the Sr segregation problem. Therefore, how to improve structural stability while maintaining electrochemical performance is a key challenge that urgently needs to be addressed. Summary of the Invention

[0005] This application provides a cathode material with high oxygen reduction catalytic activity and long-term structural stability, which is beneficial to improving the power output and service life of the battery.

[0006] This application provides a method for preparing the above-mentioned cathode material. The preparation method is simple, the raw materials are easy to obtain and the cost is low, thus it has good operability and economy.

[0007] This application also provides a cathode sheet and a solid oxide fuel cell, comprising the above-described cathode material or a cathode material prepared by the above-described preparation method.

[0008] This application provides a cathode material, wherein the cathode material comprises a perovskite ferrite core and CeO2 nanoparticles covering at least a portion of the surface of the core, and the chemical formula of the cathode material is La. a Ca 0.4-x Ce x Co b Fe c O 3-δ ,

[0009] Where x takes values ​​from 0.01 to 0.2, and the sum of the values ​​of b and c is 1.

[0010] The cathode material described above, wherein the chemical formula of the cathode material is La a Ca 0.4-x Ce x Co b Fe c O 3-δ The value of a ranges from 0.4 to 0.6.

[0011] The cathode material described above, wherein the chemical formula of the cathode material is La a Ca 0.4-x Ce x Co b Fe c O 3-δ The value of b ranges from 0.1 to 0.9.

[0012] The cathode material described above, wherein the chemical formula of the cathode material is La a Ca 0.4-x Ce x Co b Fe c O 3-δ The value of c ranges from 0.1 to 0.9.

[0013] The cathode material described above, wherein the chemical formula of the cathode material is La a Ca 0.4-x Ce x Co b Fe c O 3-δ The value of δ ranges from 0.01 to 0.05.

[0014] The cathode material described above, wherein the value of x is 0.2.

[0015] The cathode material described above, wherein the value of a is 0.6.

[0016] The cathode material described above, wherein the value of b is 0.2.

[0017] The cathode material described above, wherein the value of c is 0.8.

[0018] The cathode material described above has a diameter of 0.1 μm to 20 μm.

[0019] The cathode material described above contains CeO2 nanoparticles with a diameter of 1 nm to 500 nm.

[0020] The cathode material described above has a crystal structure of orthorhombic perovskite with space group Pnma.

[0021] This application provides a method for preparing the above-mentioned cathode material, comprising the following steps:

[0022] Lanthanum source, calcium source, cerium source, cobalt source and iron source are mixed with solvent to obtain raw material solution;

[0023] The raw material liquid is dried and then subjected to a first calcination and a second calcination in sequence to obtain cathode powder;

[0024] The cathode powder is sintered to precipitate CeO2 nanoparticles on the surface, thus obtaining the cathode material.

[0025] In the preparation method described above, the temperature of the first calcination is 900℃-1100℃, and the time is 0.1-20 hours.

[0026] In the preparation method described above, the second calcination temperature is 1300℃-1700℃ and the time is 0.1-20 hours.

[0027] In the preparation method described above, the sintering temperature is 800℃-1300℃ and the time is 0.1-10 hours.

[0028] This application provides a cathode sheet, which comprises the above-described cathode material or a cathode material prepared by the above-described preparation method.

[0029] This application also provides a solid oxide fuel cell comprising the above-described cathode material, the cathode material prepared by the above-described preparation method, or the above-described cathode sheet.

[0030] This application provides a cathode material in which a large number of highly active metal oxide CeO2 nanoparticles are deposited on the surface of the cathode material while using Ca to replace Sr. This not only avoids the problems of Sr segregation and harmful reactions between Sr and electrolyte, but also enhances the cathode material's tolerance to CO2 in the feed gas, improves the long-term structural stability, reduces the overall impedance of the battery, and increases the battery's maximum power density. Attached Figure Description

[0031] Figure 1 shows the microstructure of the cathode material (CeO2@10Ce-LCCF) in Example 1;

[0032] Figure 2 shows the microstructure of the cathode material (CeO2@20Ce-LCCF) in Example 2;

[0033] Figure 3 shows the microstructure of the cathode material (LCCF) in Comparative Example 1;

[0034] Figure 4 shows the microstructure of the cathode material (LSCF) in Comparative Example 2;

[0035] Figure 5 shows the electrochemical impedance spectroscopy of the batteries using the cathode materials of Examples 1, 2, 1, and 2 as cathodes.

[0036] Figure 6 shows the current-voltage-power density (IVP) curves of the batteries using the cathode materials of Examples 1, 2, 1, and 2 as cathodes. Detailed Implementation

[0037] To enable those skilled in the art to better understand the solutions of this application, a further detailed description of this application is provided below. The specific embodiments listed below are merely descriptions of the principles and features of this application; the examples are only for explaining this application and are not intended to limit its scope. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application.

[0038] The first aspect of this application provides a cathode material, wherein the cathode material comprises a perovskite ferrite core and CeO2 nanoparticles covering at least a portion of the surface of the core, and the chemical formula of the cathode material is La. a Ca 0.4-x Ce x Co b Fe c O 3-δ ,

[0039] Where x takes values ​​from 0.01 to 0.2, and the sum of the values ​​of b and c is 1.

[0040] In this application, the chemical formula of the cathode material is La. a Ca 0.4-x Ce x Co b Fe c O 3-δ By limiting the selection of elements in the cathode material and the proportion of each element within a specific range, the cathode material can have high oxygen reduction catalytic activity and long-term structural stability, which enhances the electrochemical performance of the battery, reduces the overall impedance of the battery, and increases the maximum power density of the battery, thus improving the power output and service life of the battery.

[0041] It is understandable that the value of x is 0.01-0.2, which means that the value of x is not lower than 0.01 and not higher than 0.2, that is, 0.01≤x≤0.2. For example, the value of x can be 0.01, 0.2 or any value between 0.01 and 0.2.

[0042] Furthermore, the cathode material of this application has a core-shell structure. The core comprises perovskite-type ferrite, and this application does not limit the elemental composition and proportion of the ferrite perovskite. The shell comprises CeO2 nanoparticles, which may be completely or incompletely coated on the surface of the core, i.e., the CeO2 nanoparticles may be completely or incompletely coated on the surface of the core. Since CeO2 nanoparticles possess excellent electrocatalytic activity, when they are completely or incompletely coated on the surface of the core, the contact area between the CeO2 nanoparticles and reactant small molecules can be increased, promoting the adsorption and dissociation of reactant small molecules by the CeO2 nanoparticles, accelerating the electrochemical reaction process, thereby giving the cathode material high oxygen reduction catalytic activity. This not only reduces the overall impedance of the battery but also improves the battery's power output. It is understood that when the CeO2 nanoparticles are completely coated on the surface of the core, it may hinder the contact between the core and reactant small molecules, thus affecting the reaction rate to some extent. When the CeO2 nanoparticles are not completely coated on the surface of the core, a synergistic effect may occur between the CeO2 nanoparticles and the core, enhancing the catalytic activity of the cathode material. Among them, small reactant molecules refer to oxygen sources, such as oxygen molecules, oxygen ions, and reactive oxygen species.

[0043] Meanwhile, the cathode material of this application does not use Sr, which can overcome the disadvantage that Sr in LSCF materials is prone to segregation during high temperature and long-term operation, and completely solve the problem of Sr reacting with electrolyte to form a high-resistivity third phase. The use of Ca to replace Sr in this application is also beneficial to enhance the cathode material's tolerance to CO2 in the feed gas, which can make the cathode material have long-term structural stability, and ultimately reduce the overall impedance of the battery and improve the battery's power output.

[0044] In the technical solution of this application, the chemical formula of the cathode material is La. aCa 0.4-x Ce x Co b Fe c O 3-δ The value of a ranges from 0.4 to 0.6.

[0045] In the technical solution of this application, the chemical formula of the cathode material is La. a Ca 0.4-x Ce x Co b Fe c O 3-δ The value of b ranges from 0.1 to 0.9.

[0046] In the technical solution of this application, the chemical formula of the cathode material is La. a Ca 0.4-x Ce x Co b Fe c O 3-δ The value of c ranges from 0.1 to 0.9.

[0047] In the technical solution of this application, the chemical formula of the cathode material is La. a Ca 0.4-x Ce x Co b Fe c O 3-δ The value of δ ranges from 0.01 to 0.05.

[0048] It is understandable that the value of a is 0.4-0.6, which means 0.4≤a≤0.6; the value of b is 0.1-0.9, which means 0.1≤b≤0.9; the value of c is 0.1-0.9, which means 0.1≤c≤0.9; and the value of δ is 0.01-0.05, which means 0.01≤δ≤0.05, where δ represents the oxygen vacancy content.

[0049] In one specific embodiment, the chemical formula of the cathode material of this application is La. a Ca 0.4-x Ce x Co b Fe c O 3-δ , where x takes the value 0.2.

[0050] In the technical solution of this application, the value of 'a' is 0.6.

[0051] In the technical solution of this application, the value of b is 0.2.

[0052] In the technical solution of this application, the value of c is 0.8.

[0053] By further limiting the ratio of x, a, b, and c, the oxygen reduction catalytic activity and long-term structural stability of the cathode material can be further improved, thereby reducing the overall impedance of the battery and increasing the maximum power density of the battery.

[0054] In one embodiment of this application, x is 0.2, a is 0.6, b is 0.2, c is 0.8, and the cell impedance of the cathode material is approximately 1.7 Ωcm. 2 The battery's maximum power density is approximately 570 mW / cm³. -2 .

[0055] In the scheme of this application, the diameter of the cathode material is 0.1μm-20μm.

[0056] Controlling the diameter of the cathode material within a specific range helps to further control the degree and state of CeO2 nanoparticle precipitation. The diameter of the cathode material affects its specific surface area and surface energy; the smaller the diameter, the larger the specific surface area and surface energy. The precipitation of CeO2 nanoparticles further increases the free energy of the reaction system, making it more difficult for CeO2 nanoparticles to precipitate. Therefore, the smaller the diameter of the cathode material, the fewer CeO2 nanoparticles are precipitated, and the smaller their size; conversely, the larger the diameter of the cathode material, the more CeO2 nanoparticles are precipitated, and the larger their size. When the diameter of the cathode material is less than 0.1 μm, CeO2 particles are difficult to precipitate; when the diameter of the cathode material is greater than 20 μm, CeO2 particles tend to aggregate and disperse unevenly.

[0057] Furthermore, the diameter of CeO2 nanoparticles ranges from 1 nm to 500 nm.

[0058] Controlling the diameter of CeO2 nanoparticles within a specific range helps to regulate their impact on the oxygen reduction catalytic activity and structural stability of cathode materials. For example, when the diameter of CeO2 nanoparticles is less than 1 nm, their catalytic active sites are limited, and it is difficult to maintain structural stability during long-term operation, resulting in insignificant or even attenuated improvement in the catalytic activity of the cathode material. When the diameter of CeO2 nanoparticles is greater than 500 nm, their distribution in the cathode material is difficult to be uniform, and it will significantly reduce the reaction sites in the core, making it difficult to further improve the catalytic activity of the cathode material or even causing it to attenuate.

[0059] In this application, the cathode material has an orthorhombic perovskite crystal structure with space group Pnma. Using a cathode material with this crystal structure makes it easier to control the composition and ratio of its doped elements to obtain better catalytic activity.

[0060] A second aspect of this application provides a method for preparing the above-mentioned cathode material, comprising the following steps:

[0061] Lanthanum source, calcium source, cerium source, cobalt source and iron source are mixed with solvent to obtain raw material solution;

[0062] The raw material liquid is dried and then subjected to a first calcination and a second calcination in sequence to obtain cathode powder;

[0063] The cathode powder is sintered to precipitate CeO2 nanoparticles on the surface, thus obtaining the cathode material.

[0064] The preparation method provided in this application is simple, involving the precipitation of metal oxide nanoparticles on cathode powder (i.e., sintering), which highly overlaps with the preparation process of SOFC cathode materials, requiring no additional steps and thus possessing operability. The lanthanum, calcium, cerium, cobalt, and iron sources used in this preparation method are all non-precious metals, abundant in resources, and inexpensive, making it economical.

[0065] The lanthanum source, calcium source, cerium source, cobalt source, and iron source can be at least one of the corresponding metal oxides, nitrates, or acetates.

[0066] The solvent can be at least one of acetone, ethanol, isopropanol, and deionized water.

[0067] In one embodiment of this application, to ensure thorough mixing, the lanthanum source, calcium source, cerium source, cobalt source and iron source can be stirred with the solvent first, and then further mixed using ultrasonic oscillation to obtain the raw material liquid.

[0068] Next, the thoroughly mixed raw material liquid is dried to remove moisture and prevent powder from flying away due to rapid evaporation, which facilitates subsequent calcination.

[0069] A pure orthorhombic perovskite structure can be obtained through the first and second calcinations, which helps to improve the catalytic activity of the cathode material.

[0070] Finally, sintering the cathode powder allows CeO2 nanoparticles to precipitate on its surface, resulting in a cathode material.

[0071] In the scheme of this application, the temperature of the first calcination is 900℃-1100℃, and the time is 0.1-20 hours.

[0072] In the scheme of this application, the temperature of the second calcination is 1300℃-1700℃, and the time is 0.1-20 hours.

[0073] During the calcination process, the dried product can be added first, and the temperature can be increased from 10℃-30℃ at a rate of 1-10℃ / min. After reaching 900℃-1100℃, the temperature can be maintained for 0.1-20 hours for the first calcination. The first calcination can transform the dried product into a mixture of metal oxide and perovskite, thereby obtaining a partially phased cathode precursor, which helps to obtain a fully phased pure perovskite structure in the subsequent second calcination.

[0074] After the first calcination, the product is cooled to 10℃-30℃ before being ground. This grinding makes the product more uniform, which helps to obtain a fully formed, pure perovskite structure in the subsequent second calcination. After grinding, a second calcination is performed, with the temperature increased from 10℃-30℃ at a rate of 1-10℃ / min, reaching 1300℃-1700℃ and held for 0.1-20 hours. This second calcination transforms the mixture of metal oxide and perovskite into pure orthorhombic perovskite, thus obtaining single-phase perovskite cathode powder. After the second calcination, the product is cooled to room temperature before being ground again. This grinding yields cathode powder with a particle size of 0.1μm-20μm, which can be used to control the precipitation degree and state of subsequent CeO2 nanoparticles.

[0075] In this application, the sintering temperature is 800℃-1300℃, and the time is 0.1-10 hours. Sintering promotes better precipitation of CeO2 nanoparticles from the cathode powder. In one embodiment of this application, the sintering is carried out in an air atmosphere, which helps the CeO2 nanoparticles precipitate uniformly and stably in an oxidizing atmosphere.

[0076] A third aspect of this application provides a cathode sheet comprising the cathode material described above or a cathode material prepared by the preparation method described above.

[0077] The cathode sheet provided in this application contains the cathode material provided in the first aspect of this application or the cathode material prepared by the preparation method provided in the second aspect of this application, and therefore also has oxygen reduction catalytic activity and structural stability for long-term operation.

[0078] A fourth aspect of this application provides a solid oxide fuel cell comprising the above-described cathode material, a cathode material prepared by the above-described preparation method, or the above-described cathode sheet.

[0079] The solid oxide fuel cell provided in this application, because it contains the cathode material provided in the first aspect of this application, the cathode material prepared by the preparation method provided in the second aspect of this application, or the cathode sheet provided in the third aspect of this application, also has oxygen reduction catalytic activity and structural stability for long-term operation.

[0080] The technical solution of this application will be further explained and illustrated below with reference to specific embodiments.

[0081] Unless otherwise specified, the experimental methods described in the following examples are generally performed under standard conditions or as recommended by the manufacturer. All reagents used are commercially available or publicly available unless otherwise specified.

[0082] Example 1:

[0083] This embodiment provides a cathode material and its preparation method, including the following steps:

[0084] (1) Weigh La2O3, CaCO3, CeO2, CoO and Fe2O3 according to the molar ratio, add acetone and stir evenly, then use an ultrasonic oscillator to oscillate at 4MHz for 30 minutes to obtain a fully mixed raw material liquid.

[0085] (2) The raw material solution was dried, and the dried product was added to a muffle furnace. The temperature was increased from 25°C to 1000°C at a rate of 5°C / min for 10 hours. After the calcined product was cooled to 25°C, it was taken out and subjected to planetary ball milling. The ball-milled product was placed in a muffle furnace and heated from 25°C to 1400°C at a rate of 5°C / min for 5 hours. After the calcined product was cooled to 25°C, it was taken out and subjected to planetary ball milling to obtain a particle size of 2μm and a chemical composition of La. 0.6 Ca 0.3 Ce 0.1 Co 0.2 Fe 0.8 O 3-δ The cathode powder (10Ce-LCCF) is used, where δ represents the oxygen vacancy content, and δ equals 0.01.

[0086] (3) The cathode powder (10Ce-LCCF) was sintered at 1150℃ and in air atmosphere for 2 hours to precipitate CeO2 nanoparticles on its surface, thus obtaining the cathode material (CeO2@10Ce-LCCF).

[0087] Example 2:

[0088] This embodiment provides a cathode material and its preparation method, including the following steps:

[0089] (1) Weigh La2O3, CaCO3, CeO2, CoO and Fe2O3 according to the molar ratio, add acetone and stir evenly, then use an ultrasonic oscillator to oscillate at 4MHz for 30 minutes to obtain a fully mixed raw material liquid.

[0090] (2) The raw material solution was dried, and the dried product was added to a muffle furnace. The temperature was increased from 25°C to 1000°C at a rate of 5°C / min for 10 hours. After the calcined product was cooled to 25°C, it was taken out and subjected to planetary ball milling. The ball-milled product was placed in a muffle furnace and heated from 25°C to 1400°C at a rate of 5°C / min for 5 hours. After the calcined product was cooled to 25°C, it was taken out and subjected to planetary ball milling to obtain a particle size of 2μm and a chemical composition of La. 0.6 Ca 0.2 Ce 0.2 Co 0.2 Fe 0.8 O 3-δ The cathode powder (20Ce-LCCF) is used, where δ represents the oxygen vacancy content, and δ equals 0.01.

[0091] (3) The cathode powder (20Ce-LCCF) was sintered at 1150℃ and in air atmosphere for 2 hours to precipitate CeO2 nanoparticles on its surface, thus obtaining the cathode material (CeO2@20Ce-LCCF).

[0092] Comparative Example 1:

[0093] This comparative example provides a cathode material and its preparation method, including the following steps:

[0094] (1) Weigh La2O3, CaCO3, CoO and Fe2O3 according to the molar ratio, add acetone and stir evenly, then use an ultrasonic oscillator to oscillate at 4MHz for 30 minutes to obtain a fully mixed raw material liquid.

[0095] (2) The raw material solution was dried, and the dried product was added to a muffle furnace. The temperature was increased from 25°C to 1000°C at a rate of 5°C / min for 10 hours. After the calcined product was cooled to 25°C, it was taken out and subjected to planetary ball milling. The ball-milled product was placed in a muffle furnace and heated from 25°C to 1400°C at a rate of 5°C / min for 5 hours. After the calcined product was cooled to 25°C, it was taken out and subjected to planetary ball milling to obtain a particle size of 2μm and a chemical composition of La. 0.6 Ca 0.4 Co 0.2 Fe 0.8 O 3-δ The cathode powder (LCCF) is used, where δ represents the oxygen vacancy content, and δ equals 0.01.

[0096] (3) The cathode powder (LCCF) was sintered at 1150°C in an air atmosphere for 2 hours to obtain the cathode material (LCCF).

[0097] Comparative Example 2:

[0098] (1) Weigh La2O3, SrCO3, CoO and Fe2O3 according to the molar ratio, add acetone and stir evenly, then use an ultrasonic oscillator to oscillate at 4MHz for 30 minutes to obtain a fully mixed raw material liquid.

[0099] (2) The raw material solution was dried, and the dried product was added to a muffle furnace. The temperature was increased from 25°C to 1000°C at a rate of 5°C / min for 10 hours. After the calcined product was cooled to 25°C, it was taken out and subjected to planetary ball milling. The ball-milled product was placed in a muffle furnace and heated from 25°C to 1400°C at a rate of 5°C / min for 5 hours. After the calcined product was cooled to 25°C, it was taken out and subjected to planetary ball milling to obtain a particle size of 2μm and a chemical composition of La. 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ The cathode powder (LSCF) is used, where δ represents the oxygen vacancy content, and δ equals 0.01.

[0100] (3) The cathode powder (LSCF) was sintered at 1150°C in an air atmosphere for 2 hours to obtain the cathode material (LSCF).

[0101] The cathode materials obtained in Examples 1 and 2, as well as Comparative Examples 1 and 2, were photographed to obtain microscopic morphology images. Simultaneously, the battery performance of an anode-supported button cell using the above cathode materials as cathodes was tested. The battery performance was tested using electrochemical impedance spectroscopy and current-voltage scanning at a temperature of 750°C, with pure hydrogen as the gas at a flow rate of 50 mL / min, NiO-YSZ as the anode, and YSZ as the electrolyte.

[0102] Figure 1 shows the microstructure of the cathode material (CeO2@10Ce-LCCF) in Example 1. It can be observed that a certain number of spherical nanoparticles have grown on the surface of the cathode material, which are in-situ precipitated CeO2 nanoparticles. Figure 1 demonstrates that the multi-component heterogeneous nanostructure of the cathode material (CeO2@10Ce-LCCF) has been successfully constructed.

[0103] Figure 2 shows the microstructure of the cathode material (CeO2@20Ce-LCCF) in Example 2. It can be observed that numerous spherical nanoparticles have grown on the surface of the cathode material, which are in-situ precipitated CeO2 nanoparticles. Figure 2 demonstrates that the multi-element heterogeneous nanostructure of the cathode material (CeO2@20Ce-LCCF) has been successfully constructed. A comparison of Figure 2 and Figure 1 shows that adding more Ce to the LCCF material can result in the precipitation of more CeO2 nanoparticles on the LCCF material surface.

[0104] Figure 3 shows the microstructure of the cathode material (LCCF) in Comparative Example 1. It can be seen that the surface of the cathode material remains smooth and flat after sintering, and no nanoparticles are precipitated.

[0105] Figure 4 shows the microstructure of the cathode material (LSCF) in Comparative Example 2. The circled areas in the figure indicate that the surface of the cathode material is covered with a layer of segregated SrO after sintering, thus becoming rough and uneven.

[0106] Figure 5 shows the electrochemical impedance spectroscopy (EIS) spectra of anode-supported button cells using the cathode materials of Examples 1, 2, Comparative Example 1, and Comparative Example 2. As can be seen from Figure 5, the cathode material of Comparative Example 2 (LSCF) corresponds to the highest cell impedance, approximately 5.9 Ωcm. 2 Secondly, the cell impedance corresponding to the cathode material (LCCF) of Comparative Example 1 is approximately 4.5 Ωcm. 2 Secondly, the cell impedance corresponding to the cathode material (CeO2@10Ce-LCCF) in Example 1 is approximately 2.8 Ωcm. 2 The lowest impedance was found in the cathode material of Example 2 (CeO2@20Ce-LCCF), at approximately 1.7 Ωcm. 2 Comparing Comparative Example 1 and Comparative Example 2, it can be seen that using Ca to replace Sr can avoid Sr segregation and harmful reactions between Sr and the electrolyte, thereby reducing the overall impedance of the corresponding battery. Comparing Example 1 and Comparative Example 1, it can be seen that the precipitation of CeO2 nanoparticles on the surface of the LCCF material can effectively reduce the overall impedance of the corresponding battery. Comparing Example 2 and Example 1, it can be seen that the precipitation of more CeO2 nanoparticles on the surface of the LCCF material helps to further reduce the overall impedance of the corresponding battery.

[0107] Figure 6 shows the IVP curves of anode-supported button cell using the cathode materials of Examples 1, 2, Comparative Example 1, and Comparative Example 2 as cathodes. As can be seen from Figure 6, the cathode material of Comparative Example 2 (LSCF) corresponds to the lowest maximum power density, approximately 120 mW / cm². -2 Secondly, the maximum power density of the cell corresponding to the cathode material (LCCF) in Comparative Example 1 is approximately 330 mW / cm². -2 Secondly, the maximum power density of the battery corresponding to the cathode material (CeO2@10Ce-LCCF) in Example 1 is approximately 380 mW / cm². -2 The cathode material in Example 2 (CeO2@20Ce-LCCF) corresponds to the highest maximum power density of the battery, approximately 570 mW / cm². -2Comparing Comparative Example 1 and Comparative Example 2, it can be seen that using Ca to replace Sr can effectively improve the maximum power density of the corresponding battery. Comparing Example 1 and Comparative Example 1, it can be seen that precipitating CeO2 nanoparticles on the surface of LCCF material can further improve the maximum power density of the corresponding battery. Comparing Example 2 and Example 1, it can be seen that precipitating more CeO2 nanoparticles on the surface of LCCF material can significantly improve the maximum power density of the corresponding battery. In addition, compared with the cathode material (LCCF) of Comparative Example 1, the cathode material (CeO2@20Ce-LCCF) of Example 2 has a 72% higher maximum power density, indicating that the method of precipitating highly active metal oxide CeO2 nanoparticles on the surface of LCCF material to construct a multi-component heterogeneous nanostructure can significantly improve the performance of the corresponding battery.

[0108] In summary, the cathode material of this application uses Ca instead of Sr, which avoids the segregation of Sr during long-term high-temperature operation and the formation of a high-resistivity third phase by Sr reaction with the electrolyte, thereby reducing the overall impedance of the corresponding battery and increasing its maximum power density. Using Ca also enhances the cathode material's tolerance to CO2 in the feed gas, resulting in better structural stability of the battery. Secondly, a large number of highly active metal oxide CeO2 nanoparticles are precipitated on the surface of the cathode material, which not only helps reduce the overall impedance of the corresponding battery but also increases its maximum power density. Furthermore, the La, Ca, Ce, Co, and Fe used in the cathode material of this application are non-precious metals, abundant in resources, and inexpensive, allowing for large-scale use. In addition, since the process of precipitating metal oxide nanoparticles on the cathode powder (i.e., sintering in an air atmosphere) highly overlaps with the cathode material preparation process of solid oxide fuel cells, no additional steps are required. Therefore, the preparation method of the cathode material of this application has good economic efficiency and operability.

[0109] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them; although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A cathode material, wherein, The cathode material comprises a perovskite-type ferrite core and CeO2 nanoparticles covering at least a portion of the surface of the core. The chemical formula of the cathode material is La. a Ca 0.4-x Ce x Co b Fe c O 3-δ , Where x takes values ​​from 0.01 to 0.2, and the sum of the values ​​of b and c is 1.

2. The cathode material according to claim 1, wherein, The chemical formula of the cathode material is La. a Ca 0.4-x Ce x Co b Fe c O 3-δ The value of a ranges from 0.4 to 0.

6.

3. The cathode material according to claim 1, wherein, The chemical formula of the cathode material is La. a Ca 0.4-x Ce x Co b Fe c O 3-δ The value of b ranges from 0.1 to 0.

9.

4. The cathode material according to claim 1, wherein, The chemical formula of the cathode material is La. a Ca 0.4-x Ce x Co b Fe c O 3-δ The value of c ranges from 0.1 to 0.

9.

5. The cathode material according to claim 1, wherein, The chemical formula of the cathode material is La. a Ca 0.4-x Ce x Co b Fe c O 3-δ The value of δ ranges from 0.01 to 0.

05.

6. The cathode material according to claim 1, wherein, The value of x is 0.

2.

7. The cathode material according to claim 1 or 6, wherein, The value of a is 0.

6.

8. The cathode material according to claim 1 or 6, wherein, The value of b is 0.

2.

9. The cathode material according to claim 1 or 6, wherein, The value of c is 0.

8.

10. The cathode material according to any one of claims 1-9, wherein, The diameter of the cathode material is 0.1μm-20μm.

11. The cathode material according to any one of claims 1-10, wherein, The CeO2 nanoparticles have a diameter of 1 nm to 500 nm.

12. The cathode material according to any one of claims 1-11, wherein, The cathode material has an orthorhombic perovskite crystal structure and a space group of Pnma.

13. The method for preparing the cathode material according to any one of claims 1-12, wherein, Includes the following steps: Lanthanum source, calcium source, cerium source, cobalt source and iron source are mixed with solvent to obtain raw material solution; The raw material liquid is dried and then subjected to a first calcination and a second calcination to obtain cathode powder. The cathode powder is sintered to precipitate CeO2 nanoparticles on the surface, thus obtaining the cathode material.

14. The preparation method according to claim 13, wherein, The first calcination temperature is 900℃-1100℃, and the time is 0.1-20 hours.

15. The preparation method according to claim 13 or 14, wherein, The second calcination temperature is 1300℃-1700℃, and the time is 0.1-20 hours.

16. The preparation method according to any one of claims 13-15, wherein, The sintering process is carried out at a temperature of 800℃-1300℃ for 0.1-10 hours.

17. A cathode plate, wherein, The cathode material comprises the cathode material according to any one of claims 1-12 or the cathode material prepared by the preparation method according to any one of claims 13-16.

18. A solid oxide fuel cell, wherein, It includes the cathode material according to any one of claims 1-12, the cathode material prepared by the preparation method according to any one of claims 13-16, or the cathode sheet according to claim 17.

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