CN116505048A - Yttrium doped cathode material and its preparation method and application - Google Patents

Abstract

The invention relates to the technical field of solid oxide fuel cells, in particular to an yttrium-doped cathode material and a preparation method and application thereof, wherein the preparation method comprises the following steps: to ABO ₃ Adding inorganic salt hydrate containing yttrium element into the cathode material solution to obtain mixed solution; adding a first complexing agent, a second complexing agent and a pH regulator into the mixed solution, mixing, and heating and stirring to obtain a gel mixture; and drying, calcining and grinding the gel mixture to obtain the yttrium-doped cathode material. The polarization resistance of the cathode material is reduced after yttrium element doping; the attenuation degree of the impedance is reduced under long-time thermal cycle use; CO resistance ₂ The ability to poison the attack increases; the high current density and long-term stability are maintained in the test of the single cell. In the aspect of mechanical properties, after yttrium element is doped, the thermal expansion coefficient can be reduced, and the fracture strength, young modulus and hardness of the cathode material are improved.

Description

A kind of yttrium-doped cathode material and its preparation method and application

technical field

The invention relates to the technical field of solid oxide fuel cells, in particular to a yttrium-doped cathode material and a preparation method and application thereof.

Background technique

Solid Oxide Fuel Cell (SOFC) is an all-solid-state chemical power generation device that directly and efficiently converts the chemical energy stored in fuel and oxidant into electrical energy at medium and high temperatures, and is environmentally friendly. At present, many studies have neglected the improvement of mechanical properties when improving the electrochemical properties of cathode materials, and mechanical properties are often the key factors affecting the life and stability of solid oxide fuel cells.

Due to ignoring the improvement of the mechanical properties of the cathode material, the cathode material of the existing solid oxide fuel cell is easy to peel off, break and deform under long-term cycle use.

Therefore, the prior art still needs to be improved and developed.

Contents of the invention

In view of the above deficiencies in the prior art, the object of the present invention is to provide a yttrium-doped cathode material and its preparation method and application, aiming at solving the problems of easy peeling, fracture and deformation of existing cathode materials.

Technical scheme of the present invention is as follows:

A preparation method of yttrium-doped cathode material, comprising the steps of:

Add an inorganic salt hydrate containing yttrium to the ABO ₃ type cathode material solution to obtain a mixed solution; wherein, A is selected from one or both of rare earth elements and alkaline earth metal elements, and B is a transition metal element;

Adding a first complexing agent, a second complexing agent and a pH regulator to the mixed solution, mixing and heating to obtain a gel mixture;

The gel mixture is dried, calcined and ground to obtain yttrium-doped cathode material.

The preparation method of the yttrium-doped cathode material, wherein the yttrium-containing inorganic salt hydrate is selected from Y(NO ₃ ) ₃ ·6H ₂ O, Y(C ₂ H ₃ O ₂ ) ₃ ·4H One or more of ₂ O, YCl ₃ ·6H ₂ O.

The preparation method of the cathode material doped with yttrium, wherein, the rare earth element is selected from one or more of La, Pr, Sm, Gd, Nd; the alkaline earth metal element is selected from Be, Mg, Ca , one or more of Sr, Ba, Ra; the transition metal element is selected from one or more of Mn, Fe, Co, Ce.

The preparation method of the cathode material doped with yttrium, wherein, the first complexing agent is selected from one or more of citric acid, malic acid, oxalic acid; the second complexing agent is selected from ethylene glycol One or more of amine tetraacetic acid, nitrilotriacetic acid, and diethylenetriamine pentacarboxylate; the pH regulator is selected from one or more of ammonia, acetone, and ethanolamine.

The preparation method of the yttrium-doped cathode material, wherein the molar ratio of the metal ion in the mixed solution to the first complexing agent, the second complexing agent and the pH regulator is 1 :(1~2):1:(9~11).

The preparation method of the yttrium-doped cathode material, wherein, in the yttrium-doped cathode material, the doping mole percentage of yttrium element at the B site is 10-20%.

The preparation method of the yttrium-doped cathode material, wherein, the temperature of the drying treatment is 150-200° C., and the time of the drying treatment is 5-10 hours.

The preparation method of the yttrium-doped cathode material, wherein, the temperature of the calcination treatment is 1000-1200° C., and the time of the calcination treatment is 5-10 hours.

An yttrium-doped cathode material prepared by the preparation method of the yttrium-doped cathode material.

Application of a yttrium-doped cathode material in a solid oxide fuel cell.

Beneficial effects: the present invention provides a yttrium-doped cathode material and its preparation method and application. The preparation method includes the steps of: adding an inorganic salt hydrate containing yttrium to the ABO ₃ type cathode material solution to obtain a mixed solution; wherein, A is selected from one or both of rare earth elements and alkaline earth metal elements, and B is a transition metal element; add the first complexing agent, the second complexing agent and the pH regulator to the mixed solution, and heat after mixing stirring to obtain a gel mixture; drying, calcining and grinding the gel mixture to obtain a yttrium-doped cathode material. In the present invention, when the material is synthesized by the sol-gel method, the inorganic salt hydrate containing the yttrium element is added, and the yttrium element will self-assemble with other elements to form a multi-phase perovskite composite when fired at a high temperature. The composite can improve the mechanical properties while maintaining the electrochemical properties of the original materials. In terms of electrochemical performance, after doping yttrium, the polarization impedance of the cathode material decreases; under long-term thermal cycle use, the attenuation of impedance decreases; the ability to resist CO ₂ poisoning and erosion increases; in the test of single cells Maintain high current density and long-term stability. In terms of mechanical properties, after doping yttrium, the thermal expansion coefficient can be reduced; under the test of the ball-ring model fracture strength at room temperature and high temperature, the fracture strength can be significantly improved; under the nanoindentation test at room temperature and high temperature, it can be significantly Improve Young's modulus and hardness.

Description of drawings

Fig. 1 is the technological process schematic diagram of the preparation method of a kind of yttrium-doped cathode material of the present invention;

Fig. 2 is the XRD pattern of BCC and the BCCY after doping Y in embodiment 1;

Fig. 3 is the polarization impedance change figure of cathode material after doping yttrium in embodiment 1;

Fig. 4 is the improvement data figure of the thermal cycle performance of cathode material after doping yttrium in embodiment 1;

Fig. 5 is the anti _- CO of cathode material after doping yttrium among the embodiment 1 The promotion data figure of erosion ability;

Fig. 6 is the promotion data diagram of the fracture strength of the cathode material under different temperature tests after doping yttrium in embodiment 1;

Fig. 7 is the promotion data figure of the Young's modulus of cathode material under different temperature tests after doping yttrium in embodiment 1;

FIG. 8 is a graph showing the improvement data of the hardness of the cathode material under different temperature tests after doping yttrium in Example 1. FIG.

Detailed ways

The present invention provides a yttrium-doped cathode material and its preparation method and application. In order to make the purpose, technical solution and effect of the present invention clearer and clearer, the present invention will be further described in detail below. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

Those skilled in the art can understand that, unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as commonly understood by those of ordinary skill in the art to which this invention belongs. It should also be understood that terms, such as those defined in commonly used dictionaries, should be understood to have meanings consistent with their meaning in the context of the prior art, and unless specifically defined as herein, are not intended to be idealized or overly Formal meaning to explain.

As shown in Figure 1, the present invention provides a kind of preparation method of the cathode material of yttrium doping, comprises steps:

Step S10: adding an inorganic salt hydrate containing yttrium to the ABO ₃ -type cathode material solution to obtain a mixed solution; wherein, A is selected from one or both of rare earth elements and alkaline earth metal elements, and B is a transition metal element;

Step S20: Adding the first complexing agent, the second complexing agent and the pH regulator to the mixed solution, mixing and heating to obtain a gel mixture;

Step S30: Drying, calcining and grinding the gel mixture to obtain yttrium-doped cathode material.

In this embodiment, when the cathode material is synthesized by the sol-gel method, an inorganic salt hydrate containing yttrium is added to obtain a mixed solution, and a first complexing agent, a second complexing agent and a pH adjustment are added to the mixed solution agent, adjust the pH value of the mixed solution through the pH regulator, use the first complexing agent and the second complexing agent to form complexes with the metal ions in the mixed solution, so that the components of the raw materials are evenly mixed, and the purity of the product is improved. And the stoichiometric ratio can be accurately controlled; finally, the gel mixture is dried and fired sequentially through drying and calcination. When fired at high temperature, the yttrium element will self-assemble with other elements to form a multi-phase perovskite Mineral composites, which can improve the mechanical properties while maintaining the electrochemical properties of the original materials. Specifically, the doping of yttrium is mainly used for the doping of the B site. By doping the B site of the ABO ₃ cathode material, the cathode material can be improved at room temperature (25°C) to high temperature (700°C ) Mechanical properties in multiple temperature ranges. Using the above preparation method, after yttrium doping in the cathode material, the impedance is reduced by more than 20%, the cycle attenuation is reduced by more than 20%, the thermal expansion coefficient is reduced by more than 30%, the fracture strength is increased by more than 70%, and the Young's modulus and hardness are increased by 50%. %above.

Further, the above preparation method can do yttrium doping to all ABO ₃ type cathode materials, so as to realize the improvement of mechanical properties and maintain the original electrochemical properties. As an example, the ABO ₃ type cathode material may be, but not limited to, BSCF, LSCF, LSM, SSC, BCC.

In some embodiments, in addition to the sol-gel method for preparing yttrium-doped cathode materials, solid-phase methods, coprecipitation methods, hydrothermal methods, template methods, etc. can also be used; wherein, the sol-gel method is used to prepare yttrium-doped cathode materials The doped cathode material has the best effect. The yttrium-doped cathode material is mainly prepared by the sol-gel method, which has the least impurities and the highest purity. The particle size of the cathode material is the most suitable and uniform, the process is easy to control, and the stoichiometry is the most accurate.

In some embodiments, in the step S10, the ABO ₃ type cathode material solution is obtained by mixing metal nitrate solutions containing different metal ions, that is, a nitrate solution of one or both of rare earth elements and alkaline earth metal elements and Nitrate solutions of transition metal elements are mixed; taking BaCo _0.7 Ce _0.3 as an example, the mixture of Ba(NO ₃ ) ₂ , Co(NO ₃ ) ₂ 6H ₂ O, Ce(NO ₃ ) ₃ 6H ₂ O After heating and stirring in water until fully dissolved, the ABO ₃ type cathode material solution is obtained.

In some embodiments, the yttrium-containing inorganic salt hydrate is selected from but not limited to Y(NO ₃ ) ₃ .6H ₂ O, Y(C ₂ H ₃ O ₂ ) ₃ .4H ₂ O, YCl ₃ . One or more of 6H ₂ O; when fired at high temperature, the yttrium element in the inorganic salt hydrate will self-assemble with the elements in the ABO _3- type cathode material to form a multi-phase perovskite composite, The composite can improve the mechanical properties of the cathode material while maintaining the electrochemical properties of the original material. That is, the thermal expansion coefficient of the cathode material can be reduced, and the fracture strength, Young's modulus and hardness of the cathode material can be improved.

In some embodiments, the rare earth element is selected from but not limited to one or more of La, Pr, Sm, Gd, Nd; the alkaline earth metal element is selected from but not limited to Be, Mg, Ca, Sr, One or more of Ba, Ra; the transition metal element is selected from but not limited to one or more of Mn, Fe, Co, Ce; the ABO ₃ type perovskite structure cathode material composed of these elements When the B site is doped with yttrium element, the mechanical properties of the cathode material can be effectively improved while maintaining the original electrochemical properties.

In some embodiments, the first complexing agent is selected from but not limited to one or more of citric acid, malic acid, oxalic acid; the second complexing agent is selected from but not limited to ethylenediaminetetraacetic acid , one or more of nitrilotriacetic acid, diethylenetriamine pentacarboxylate; the pH regulator is selected from but not limited to one or more of ammonia, acetone, ethanolamine.

In a preferred embodiment, the first complexing agent is citric acid; the second complexing agent is ethylenediaminetetraacetic acid; and the pH regulator is ammonia water.

Specifically, during the preparation of cathode materials by the sol-gel method, citric acid (CA) can form complexes with metal ions; during the gel process, as the solvent evaporates, metal cations and citric acid are cross-linked and polycondensed The formation of a three-dimensional network structure can make the components of the raw materials evenly combined, improve the purity of the product, and can accurately control the stoichiometric ratio. Ethylenediaminetetraacetic acid (EDTA) is a good complexing agent like citric acid, which can form stable water-soluble complexes with alkaline earth metals, rare earth elements and transition metals, and can be stable in alkaline solution Existence, thus greatly improving the complexing ability of ions, often used together with CA. In order to promote dissolution, it is necessary to add an appropriate amount of ammonia water to adjust the pH value of the solution. Because the pH value of the solution is too low, the solubility of EDTA acid becomes smaller, resulting in precipitation. If the pH value is too high, it will lead to the competitive complexation of ammonia and metal ions. , and the temperature at which the solution becomes gelatinized increases.

In some embodiments, the molar ratio of the metal ion in the mixed solution to the first complexing agent, the second complexing agent and the pH regulator is 1:(1~2):1: (9~11).

In a preferred embodiment, the molar ratio of the metal ion in the mixed solution to the first complexing agent, the second complexing agent and the pH regulator is 1:2:1:10, and the mixing Under the molar ratio of the metal ions in the liquid to the first complexing agent, the second complexing agent and the pH regulator, a uniformly mixed gel mixture can be obtained.

In some embodiments, in the yttrium-doped cathode material, the doping mole percentage of yttrium element at the B site is 10-20%, and the doping of the yttrium element is mainly used for the doping of the B site, compared to Mn , Fe, Co, etc. Yttrium element itself is not an element that can be doped at the B site to improve the oxygen reduction ability of the cathode. Excessive yttrium content will affect the electrochemical performance of the original material. Yttrium doping is mainly used to improve the strength of the material, and too little will not increase the mechanical properties. Therefore, controlling the doping mole percentage of yttrium element at the B site to be 10-20% can effectively improve the mechanical properties of the cathode material while maintaining the original electrochemical performance of the yttrium-doped cathode material.

In a preferred embodiment, in the yttrium-doped cathode material, the doping mole percentage of yttrium element at the B site is 15%, which greatly improves the mechanical properties of the cathode material and maintains the original electrochemical properties. performance.

In some embodiments, the temperature of the drying treatment is 150-200° C., and the time of the drying treatment is 5-10 hours. Drying the gel mixture under this condition can play a role in decondensation. The water on the surface of the gel eliminates the pores of the gel, densifies it, and makes the phase composition and microstructure of the product meet the requirements of product performance.

In some embodiments, the temperature of the calcination treatment is 1000-1200° C., and the time of the calcination treatment is 5-10 hours. Carrying out the high-temperature calcination treatment under this condition can make the yttrium element self-assemble with other elements A heterogeneous perovskite-type composite, that is, a yttrium-doped cathode material, is generated; the composite can improve the mechanical properties while maintaining the electrochemical properties of the original material.

In a preferred embodiment, the temperature of the calcination treatment is 1000° C., and the time of the calcination treatment is 5 hours.

In addition, the present invention also provides a yttrium-doped cathode material prepared by using the preparation method of the yttrium-doped cathode material.

In this embodiment, the yttrium-doped cathode material prepared by the above-mentioned preparation method of the yttrium-doped cathode material can not only maintain the original electrochemical performance, but also improve the mechanical performance; further, maintain the electrochemical performance to reflect In: the polarization impedance of the cathode is reduced; the attenuation of the impedance is reduced under long-term thermal cycle use; the ability to resist CO ₂ poisoning and erosion is increased; in the test of a single cell, it maintains a high current density and a long time Stability; improved mechanical properties are reflected in: the coefficient of thermal expansion can be reduced; under the test of the ball-ring model fracture strength at room temperature and high temperature, the fracture strength can be significantly improved; under the nanoindentation test at room temperature and high temperature, Young's can be significantly improved modulus and hardness.

Specifically, after the ABO ₃ cathode material is doped with yttrium, the impedance is reduced by more than 20%, the cycle attenuation is reduced by more than 20%, the thermal expansion coefficient is reduced by more than 30%, the fracture strength is increased by more than 70%, and the Young's modulus and hardness are increased by 50%. %above.

In addition, the invention also provides an application of a yttrium-doped cathode material in a solid oxide fuel cell.

In this embodiment, the use of the yttrium-doped cathode material in the solid oxide fuel cell can prevent problems such as peeling, fracture and deformation under long-term cycle use, and improve the performance of the solid oxide fuel cell. service life.

Further examples are given below to describe the present invention in detail. It should also be understood that the following examples are only used to further illustrate the present invention, and should not be construed as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art according to the above contents of the present invention all belong to the present invention scope of protection.

Example 1

In this example, BaCo _0.7 Ce _0.15 Y _0.15 (BCCY) was prepared by doping 15% Y element in 0.1 mol of BaCo _0.7 Ce _0.3 (BCC) at the B site, by using the sol-gel method, and adding an appropriate amount of Y(NO ₃ ) ₃ ·6H ₂ O is doped, as follows:

Mix 26.123g Ba(NO ₃ ) ₂ , 20.3721g Co(NO ₃ ) ₂ 6H ₂ O, 6.5433g Ce(NO ₃ ) ₃ 6H ₂ O and dissolve them in water, heat and stir until fully dissolved, Obtain ABO ₃ type cathode material solution;

Add 5.7452g Y(NO ₃ ) ₃ 6H ₂ O to the ABO ₃ type cathode material solution to obtain a mixed solution; and weigh 58.448g ethylenediaminetetraacetic acid, 84.056g citric acid monohydrate, and measure 77.07ml Ammonia is added in the mixed solution, and the mol ratio of the metal ion in the mixed solution to ethylenediaminetetraacetic acid, citric acid monohydrate and ammonia is 1:1:2:10, and the mixed sol is heated and stirred until The water is fully evaporated, the solution becomes gel, and the gel mixture is obtained;

The gel mixture is placed in an oven at 150-200°C and dried for 5-10 hours; then transferred to a muffle furnace for firing at 1000°C for 5 hours, and the fired agglomerated powder is ground to obtain yttrium-doped heterogeneous cathode material (BCCY).

The performance test and characterization of the yttrium-doped cathode material prepared in this embodiment are as follows:

1. XRD characterization of yttrium-doped cathode materials

The XRD analysis of the yttrium-doped cathode material (BCCY) was carried out, and it was found that during the firing process, the yttrium element made the original BCC automatically recombine into a two-phase composite material, including BaCe _0.094 Co _0.74 with a phase content of 89%. Y _0.166 O ₃ and BaCe _0.86 Co _0.11 Y _0.03 O ₃ with 11% phase content. The XRD patterns before and after doping are shown in Figure 2, and the cathode material after doping Y element is a two-phase composite material.

2. Electrochemical test after doping

The electrochemical test is mainly carried out by Keithley2460 digital source meter and Princeton electrochemical workstation. This includes impedance, thermal cycling, and cathode performance testing after _CO2 attack.

Sample impedance testing is achieved by symmetric cell electrochemical impedance spectroscopy (EIS). The symmetric cell was fabricated as follows: a dense BZCYYb disc with a diameter of 15 mm and a thickness of 0.8 mm was prepared by dry pressing 0.4 g of powder, followed by sintering at 1450 °C for 5 h.

First, the cathode powder obtained by grinding the yttrium-doped cathode material (BCCY) was dispersed in a premixed solution of glycerol, ethylene glycol, and isopropanol. Colloidal suspensions were made from these mixtures by planetary milling at 400 rpm for half an hour. The suspension was deposited on both sides of BZCYYb by spray gun spraying and calcined at 800 °C for 2 h in air atmosphere to obtain porous electrodes. The test frequency range is 0.01Hz to 100kHz, the impedance signal amplitude is 10mV, and the impedance spectrum test is completed at 450-700°C under the condition of symmetrical battery open circuit voltage. Improvement of Impedance Performance As shown in Figure 3, the doping of Y can reduce the polarization impedance by 28% (0.32Ωcm ² to 0.23Ωcm ² , 600°C).

The thermal cycle test is carried out at 300-600°C. First measure the polarization impedance of the symmetrical battery at 600°C, then naturally cool down to 300°C for 10 minutes, and then heat up to 600°C at a temperature of 10°C/min. For the second impedance test, 35 thermal cycle tests were repeated in this way. The thermal cycle performance improvement is shown in Figure 4. After 35 thermal cycles, the polarization impedance attenuation was reduced from 62.5% to 37.8%.

The test of resistance to CO ₂ erosion is carried out under the air with 1% CO ₂ content. Air was first passed through for impedance testing, then air with 1% CO ₂ content was passed through for 300 minutes, and the impedance change during the process was recorded, and then air was passed through for 300 minutes, and the recovery of impedance during the process was recorded. As shown in Figure 5, _{the ability to resist CO 2 erosion has also been greatly improved. Under 1% CO 2 erosion for} 300 minutes, the polarization impedance of BCCY increased by 7.8 times to 2.2Ωcm ² , while The polarization impedance of BCC increased by 7.8 times to 3.7Ωcm ² .

For single-cell performance testing, two half-cells, BZCYYb|NiO+BZCYYb and YSZ|NiO+YSZ, were prepared by tape casting, and the cathode was deposited by spraying, and fired at 800°C for 2 hours to obtain a single cell. After that, the performance of the single cell is tested in the environment of air and hydrogen. Single-cell power density of BCCY cathode doped with Y element, under BZCYYb electrolyte, 619 mW·cm ^-2 (700℃), stability for 280h; under YSZ electrolyte, 1026 mW·cm ^-2 (800℃), Stability 380h.

3. Mechanical test after doping

A dilatometer measures the coefficient of thermal expansion. The cathode material was prepared into a dense cathode sheet of 4×3×10 mm by dry pressing for testing.

High temperature creep tester to test the breaking strength. Using the ball-ring model, the cathode discs with different thicknesses and diameters are crushed, and the load-displacement curve is recorded during the process, and then the fracture strength of the material is obtained through calculation. The BCC cathode powder and the Y-doped BCCY powder were pressed into shape under a pressure of 12 MPa by means of powder compaction, and then fired at 1100° C. for 5 hours to obtain a dense cathode sheet. Using Kejing's high-temperature creep tester, equipped with a spherical punch, and placing the fired circular cathode sheet between the ring table and the punch. In the form of controlled displacement, a force is applied to the cathode sheet until the cathode sheet breaks. In this process, the load-displacement curve of the whole process is obtained through displacement and pressure sensors. The fracture strength of the two materials can be obtained by analyzing and processing the curve. In order to ensure the credibility of the experimental results, 25 fracture experiments were carried out for each material. With 65% confidence, [ , /> ] The average value within the confidence interval is used as the final experimental data. The same method is used for high temperature tests at 150, 300, 450, 600, and 700°C. As shown in Figure 6, the breaking strength can be increased by 76.8% (from 27.98MPa to 49.46MPa).

The Young's modulus and hardness were measured by a nanoindenter, using a Bruker nanoindenter Hysitron PI 89 series, and a berkovich type probe to conduct an indentation test on the cathode material to control the displacement of the probe. In order to avoid the contingency of the experimental results, a multi-regional dot test was carried out on the sample, and a 65% confidence level was taken, [ , /> ] The average value within the confidence interval is used as the final experimental data. During the test, the method of controlling the displacement was used to carry out the indentation test of 1500nm to obtain the load-displacement curve, and the Young's modulus and hardness of the cathode material were calculated from the slope of the unloading point, the maximum load point and the contact area. The material is heated in vacuum to obtain the Young's modulus and hardness of the cathode at different temperatures, especially at the operating temperature. The improvement of Young's modulus and hardness is shown in Figure 7 and Figure 8. The Young's modulus and hardness under the nanoindentation test were increased by 56% and 58% (27.33GPa to 42.64GPa, 1.29GPa to 2.04GPa).

Therefore, the electrochemical and mechanical properties of BCCY (BaCo _0.7 Ce _0.15 Y _0.15 O) doped with yttrium element are greatly improved compared with BCC (BaCo _0.7 Ce _0.3 O).

In summary, the present invention provides a yttrium-doped cathode material and its preparation method and application. The preparation method includes the steps of: adding an inorganic salt hydrate containing yttrium to the ABO ₃ type cathode material solution to obtain a mixed solution ; Wherein, A is selected from one or both of rare earth elements and alkaline earth metal elements, and B is a transition metal element; Add the first complexing agent, the second complexing agent and the pH regulator in the mixed solution, mix Afterwards, a gel mixture is obtained by heating and stirring; the gel mixture is dried, calcined and ground to obtain a yttrium-doped cathode material. In the present invention, when the material is synthesized by the sol-gel method, the inorganic salt hydrate containing the yttrium element is added, and the yttrium element will self-assemble with other elements to form a multi-phase perovskite composite when fired at a high temperature. The composite can improve the mechanical properties while maintaining the electrochemical properties of the original materials. In terms of electrochemical performance, after doping yttrium, the polarization impedance of the cathode material decreases; under long-term thermal cycle use, the attenuation of impedance decreases; the ability to resist CO ₂ poisoning and erosion increases; in the test of single cells Maintain high current density and long-term stability. In terms of mechanical properties, after doping yttrium, the thermal expansion coefficient can be reduced; under the test of the ball-ring model fracture strength at room temperature and high temperature, the fracture strength can be significantly improved; under the nanoindentation test at room temperature and high temperature, it can be significantly Improve Young's modulus and hardness.

It should be understood that the application of the present invention is not limited to the above examples, and those skilled in the art can make improvements or changes according to the above descriptions, and all these improvements and changes should belong to the scope of protection of the appended claims of the present invention.

Claims (10)

1. a preparation method of yttrium-doped cathode material, is characterized in that, comprises steps: Add an inorganic salt hydrate containing yttrium to the ABO ₃ type cathode material solution to obtain a mixed solution; wherein, A is selected from one or both of rare earth elements and alkaline earth metal elements, and B is a transition metal element; Adding a first complexing agent, a second complexing agent and a pH regulator to the mixed solution, mixing and heating to obtain a gel mixture; The gel mixture is dried, calcined and ground to obtain yttrium-doped cathode material. 2. The preparation method of the yttrium-doped cathode material according to claim 1, characterized in that, the inorganic salt hydrate containing yttrium element is selected from Y(NO ₃ ) ₃ 6H ₂ O, Y(C ₂ One or more of H ₃ O ₂ ) ₃ ·4H ₂ O, YCl ₃ ·6H ₂ O. 3. the preparation method of the cathode material of yttrium doping according to claim 1 is characterized in that, described rare earth element is selected from one or more in La, Pr, Sm, Gd, Nd; The element is selected from one or more of Be, Mg, Ca, Sr, Ba, and Ra; the transition metal element is selected from one or more of Mn, Fe, Co, and Ce. 4. the preparation method of the cathode material of yttrium doping according to claim 1, is characterized in that, described first complexing agent is selected from one or more in citric acid, malic acid, oxalic acid; Two complexing agents are selected from one or more of ethylenediaminetetraacetic acid, nitrilotriacetic acid, diethylenetriamine pentacarboxylate; the pH regulator is selected from one or more of ammonia, acetone, ethanolamine kind. 5. the preparation method of the cathode material of yttrium doping according to claim 1 is characterized in that, the metal ion in the mixed solution is mixed with the first complexing agent, the second complexing agent and the The molar ratio of the pH regulator is 1:(1~2):1:(9~11). 6. The preparation method of the yttrium-doped cathode material according to claim 1, characterized in that, in the yttrium-doped cathode material, the doping mole percentage of yttrium element at the B site is 10-20%. 7 . The preparation method of yttrium-doped cathode material according to claim 1 , characterized in that, the temperature of the drying treatment is 150-200° C., and the time of the drying treatment is 5-10 hours. 8 . The preparation method of yttrium-doped cathode material according to claim 1 , characterized in that, the temperature of the calcination treatment is 1000-1200° C., and the time of the calcination treatment is 5-10 hours. 9. A yttrium-doped cathode material prepared by the preparation method of the yttrium-doped cathode material according to any one of claims 1-8. 10. A use of the yttrium-doped cathode material as claimed in claim 9 in a solid oxide fuel cell.