Perovskite material, preparation method of perovskite material, solid oxide electrolytic cell and cathode of solid oxide electrolytic cell

Abstract

The invention belongs to the related technical field of batteries, and particularly relates to a perovskite material and a preparation method thereof, and a solid oxide electrolytic tank and a cathode thereof. According to the preparation method of the perovskite material provided by the invention, through high-temperature annealing and reducing atmosphere heat treatment, CeO2 nanocrystals and transition metal nanoparticles are sequentially subjected to in-situ precipitation on a perovskite oxide, so that a heterostructure of a CeO2-transition metal nanoparticle catalyst with thermodynamic stability is formed. Compared with an impregnation method and an in-situ precipitation method, the CeO2-transition metal nanoparticles obtained by the in-situ precipitation method are uniformly distributed on a perovskite oxide matrix and have a very good nesting effect with the matrix, the micro-nano structure is more stable, the phenomenon of performance reduction caused by particle aggregation in the operation process of the cell can be effectively prevented, and the performance of the cell is improved. And the innovative CeO2-transition metal nanoparticle catalyst is introduced, so that the catalytic activity of the electrode material and the overall performance of the electrolytic tank can be greatly improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of battery related technology, and particularly relates to a perovskite material and a preparation method thereof, and a solid oxide electrolysis cell and a cathode thereof. BACKGROUND

[0002] At present, the key material of solid oxide electrolysis cell (SOEC) is a research hotspot in the field of energy materials. In the solid oxide electrolysis cell, the catalytic activity of the cathode material directly affects the performance of the cell. Among them, the commonly used cathode material is Ni-YSZ (nickel-yttria stabilized zirconia), however, in the long-term operation process, the Ni-YSZ electrode may be deactivated due to the coarsening of nickel particles, phase separation of YSZ or carbon deposition (especially when using hydrocarbons as fuel). Perovskite materials have the characteristics of mixed ionic and electronic conduction (MIEC, Mixed Ionic and Electronic Conductor) and can be used as a substitute material for Ni-YSZ.

[0003] Perovskite oxides are the most widely studied materials in SOEC cathode materials, and the general structure of single perovskite is AB03, A and B sites represent two different cations, and A / B site cations can maintain the stability of the perovskite structure within the tolerance factor (0.77-1). The advantage of perovskite structure lies in its high flexibility and adjustability. By replacing the cations at A site or B site, or partially doping between A site and B site, the electronic structure and physical and chemical properties of perovskite materials can be adjusted to meet different application requirements. Most perovskite electrode materials are mixed ionic and electronic conductors, which have better stability and stronger carbon deposition resistance compared with Ni-YSZ materials. In addition, perovskite electrode materials also have good redox stability and impurity resistance.

[0004] However, compared with traditional nickel-based catalysts, the electrocatalytic activity of perovskite materials is insufficient, which hinders their application in SOEC. Modifying perovskite materials to improve their catalytic performance is a necessary condition for their wider application. By doping appropriate elements at the A site or B site of the perovskite and then in-situ precipitating uniform distribution of nano-particle catalysts on the surface of the perovskite, the catalytic activity of the perovskite material can be improved, thereby effectively improving the electrocatalytic performance of the SOEC cathode material.

[0005] However, so far, the in-situ precipitation modification method mainly focuses on the in-situ precipitation of single transition metal or alloy catalysts from perovskite. The precipitated single transition metal or alloy catalyst still has poor catalytic activity and stability.

[0006] Cerium (Ce) has attracted much attention due to its abundant reserves. Its oxide, cerium dioxide (CeO2), exhibits good ionic conductivity due to its cubic fluorite crystal structure, in which oxygen vacancies can migrate well. Furthermore, CeO2 is thermally reduced at high temperatures, reducing tetravalent cerium in its crystal structure to trivalent cerium. This change in ionic valence leads to the formation of oxygen vacancies, resulting in a large number of oxygen vacancies. Oxygen vacancies are important reaction sites on the CeO2 crystal surface, playing a crucial role in oxygen capture and dissociation. The widespread interest in cerium-based catalysts stems from this unique advantage of oxygen vacancies. As a representative of rare earth elements, Ce possesses a unique electron configuration: [Ce]4f 1 5d 1 6s 2 Its 4f orbital is highly localized and can efficiently store electrons. More electron migration helps oxygen adsorption and dissociation on the crystal surface, giving CeO2 outstanding oxygen storage and release capabilities, thereby improving the oxidation performance of the catalyst.

[0007] Creating heterostructures is one of the main methods for preparing highly active materials in catalytic and electrocatalytic systems. Impregnating perovskite materials with CeO2-transition metal nanoparticles significantly improves the electrochemical performance of electrolytic cells, making them promising candidates for electrochemical systems. However, due to the weak particle-substrate interaction, impregnated CeO2-transition metal nanoparticles tend to aggregate at high temperatures, inevitably leading to performance degradation over time. Summary of the Invention

[0008] Therefore, the technical problem to be solved by the present invention is to overcome the defect in the prior art that the interaction between impregnated CeO2-transition metal nanoparticles and perovskite substrate is weak, resulting in severe degradation of battery performance as the operating time increases. Thus, the present invention provides a perovskite material and its preparation method, as well as a solid oxide electrolytic cell and its cathode.

[0009] To this end, the present invention provides the following technical solution.

[0010] In a first aspect, this application provides a method for preparing a perovskite material, comprising the following steps:

[0011] Step S1: The perovskite oxide powder is heated to 900-1300℃ for annealing to obtain annealed perovskite oxide powder; wherein the perovskite oxide is an ABO3 type perovskite oxide doped with cerium ions at the A site and transition metal ions at the B site, and the cerium ions are doped in the crystal lattice of the perovskite oxide.

[0012] Step S2: The annealed perovskite oxide powder is placed in a reducing atmosphere for heat treatment.

[0013] In one optional embodiment, in step S1, when heating the perovskite oxide powder, the heating rate is 1–2 °C / min; and / or, the annealing time is 2–12 h. Studies have found that both the heating rate and annealing time significantly affect the precipitation, size, and quantity of cerium oxide nanocrystals, and the precipitation effect of cerium oxide nanocrystals is better within the aforementioned heating rate and annealing time ranges.

[0014] Preferably, in step S1, the perovskite oxide powder is heated to 1200°C and held at that temperature for an effective duration to obtain annealed perovskite oxide powder. Experimental studies have shown that when the annealing temperature is 1200°C, the in-situ precipitation of cerium oxide is the highest, and the appearance of the material is the most ideal.

[0015] In one optional embodiment, in step S1, the transition metal ion includes at least one of cobalt ion, nickel ion, iron ion, copper ion and titanium ion;

[0016] And / or, the A-site of the perovskite oxide is at least one of La, Pr, Sr, Ba and Sm;

[0017] And / or, the B site of the perovskite oxide is at least one of Ti, Fe, Co, Ni and Cu.

[0018] In one alternative embodiment, the perovskite oxide is La. 1-x-y Ce y Co z Ti 1-z O 3-δ Where x takes values ​​from 0 to 0.3, y takes values ​​from 0.01 to 0.1, and z takes values ​​from 0 to 0.5, and the value of z is not 0.

[0019] In one optional embodiment, in step S2, the reducing atmosphere includes at least one of a nitrogen-hydrogen mixture, a nitrogen-carbon mixture, and a hydrocarbon mixture.

[0020] And / or, the volume ratio of hydrogen in the reducing atmosphere is 5-20%;

[0021] And / or, the conditions for the heat treatment include: a temperature of 750–850°C and a time of 2–10 hours.

[0022] In one optional embodiment, the method for preparing the perovskite oxide includes a sol-gel method, wherein the preparation process of the perovskite oxide includes:

[0023] According to the stoichiometric ratio, the raw materials used to generate the perovskite oxide are added to the solvent, and then citric acid is added according to the mass ratio of metal ions:citric acid = 1: (1~2). The mixture is stirred and heated at 70~100℃ to obtain a gel.

[0024] The gel was heated to 320–360°C for pre-sintering to obtain a dry gel.

[0025] The dry gel is heated to a temperature not lower than 1400°C at a heating rate of 5–10°C / min, kept at that temperature for 5–20 h, and then cooled to room temperature at a cooling rate of 5–10°C / min.

[0026] Experimental studies have shown that firing the dry gel in air at a temperature not lower than 1400℃ promotes the incorporation of cerium ions into the perovskite oxide lattice. The cerium ions that enter the lattice are not oxidized to cerium oxide during firing; instead, they grow in situ from the matrix as cerium oxide during subsequent high-temperature annealing. Only cerium oxide grown in this in situ can be embedded in the matrix, exhibiting extremely strong adhesion. However, at firing temperatures below 1400℃, cerium ions cannot be incorporated into the perovskite oxide lattice and are oxidized to cerium oxide during firing. The resulting cerium oxide merely adheres mechanically to the matrix surface, exhibiting extremely poor adhesion and typically detaching after ultrasonic treatment.

[0027] In an alternative embodiment, the perovskite oxide is La 1-x-y Ce y Co z Ti 1-z O 3-δ In this case, the raw materials used to react and generate the perovskite oxide include lanthanum nitrate, cerium nitrate, cobalt nitrate, and tetrabutyl titanate.

[0028] Secondly, this application provides a perovskite material prepared by the above-described preparation method, wherein the perovskite material comprises perovskite oxide and cerium oxide and transition metal particles that are sequentially precipitated in situ from the perovskite oxide.

[0029] Thirdly, this application provides a solid oxide electrolytic cell cathode, comprising the aforementioned perovskite material.

[0030] Fourthly, this application provides a solid oxide electrolytic cell, including the above-mentioned perovskite material or solid oxide electrolytic cell cathode.

[0031] The technical solution of this invention has the following advantages:

[0032] The method for preparing perovskite materials provided in this application firstly involves high-temperature annealing, which causes cerium ions in the perovskite oxide lattice to precipitate in situ as CeO2 nanocrystals on the surface of the perovskite oxide. Then, heat treatment in a reducing atmosphere causes transition metal ions to precipitate in situ as transition metal nanoparticles, thereby forming a thermodynamically stable CeO2-transition metal nanoparticle catalyst heterostructure. Compared to the impregnation method, the CeO2-transition metal nanoparticles obtained by the in-situ precipitation method are uniformly distributed on the perovskite oxide matrix and exhibit excellent nesting with the matrix. This results in a more stable micro / nano structure, effectively preventing performance degradation caused by particle aggregation during battery operation. Furthermore, the introduction of this innovative CeO2-transition metal nanoparticle catalyst can significantly improve the catalytic activity of the electrode material and the overall performance of the electrolyzer.

[0033] Furthermore, in the preparation method of this application, perovskite oxide is first subjected to high-temperature annealing in air to precipitate perfect CeO2 nanocrystals. Then, the annealed product is subjected to reduction heat treatment in a reducing atmosphere to precipitate transition metal nanoparticles. On the one hand, the precipitated CeO2 nanocrystals can form composite nano-reinforcement with the transition metal nanoparticles. On the other hand, the reduction heat treatment in a reducing atmosphere does not affect the structure and composition of the previously precipitated CeO2 nanocrystals, which ensures the catalytic activity of CeO2. This is because CeO2 has both high oxygen ion conductivity and electronic conductivity, and the hydrogen reducing atmosphere does not reduce the CeO2 nanocrystals to metallic Ce, thus ensuring catalytic activity and mixed conductivity. Attached Figure Description

[0034] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0035] Figure 1 These are the XRD patterns of the LCCT, LCCT1200, and LCCT1200-R samples prepared in Example 1 of this invention;

[0036] Figure 2 These are SEM microstructure images of the LCCT1200 sample prepared in Example 1 of this invention at different magnifications;

[0037] Figure 3 These are SEM microstructure images of the LCCT1200-R sample prepared in Example 1 of this invention at different magnifications;

[0038] Figure 4 This is an EDS image of the LCCT1200 sample prepared in Example 1 of this invention;

[0039] Figure 5 This is an EDS image of the LCCT1200-R sample prepared in Example 1 of this invention. Detailed Implementation

[0040] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0041] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0042] Example 1

[0043] The perovskite material La was prepared according to the following method. 0.75 Ce 0.05 Co 0.5 Ti 0.5 O 3-δ :

[0044] (1) Synthesis of La by sol-gel method 0.75 Ce 0.05 Co 0.5 Ti 0.5 O 3-δ According to the stoichiometric ratio of the chemical formula, analytical grade lanthanum nitrate, cerium nitrate, cobalt nitrate, and tetrabutyl titanate were weighed and added to N,N-dimethylformamide (hereinafter referred to as DMF) solution. Citric acid was weighed according to the mass ratio of metal ions to citric acid = 1:1.5 and added to DMF solution. The liquid was stirred evenly with a magnetic stirrer and heated to 80°C to obtain a gel.

[0045] (2) The gel obtained in step (1) is heated to 360°C on a heating table for pre-sintering to obtain a dry gel;

[0046] (3) The dry gel obtained in step (2) is placed in a muffle furnace and heated to 1400°C at a heating rate of 8°C / min. After holding at the temperature for 12 hours, it is cooled to room temperature at a cooling rate of 8°C / min to obtain LCCT powder.

[0047] (4) The LCCT powder obtained in step (3) is placed in a muffle furnace for annealing. The temperature is increased at a rate of 1℃ / min and held at 1200℃ for 2h to obtain annealed LCCT, which is denoted as LCCT1200.

[0048] (5) The LCCT1200 obtained in step (4) is placed in a reducing atmosphere of 850℃ and 5%H2-95%N2 for reduction treatment. The resulting product is denoted as LCCT1200-R.

[0049] (6) The LCCT1200-R powder obtained in step (5) is placed in a planetary ball mill and ball-milled for 48 hours. The ball-milled product is dried and sieved to obtain the final perovskite material powder.

[0050] The stability of the perovskite phase, the precipitation of CeO2, and the precipitation of Co metal nanoparticles in this embodiment were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS), respectively. The XRD patterns show (e.g.) Figure 1 As shown in the figure, the LCCT phase synthesized by the sol-gel method does not have obvious impurity peaks, and the LCCT phase shows obvious CeO2 peaks after annealing at 1200℃, and Co metal impurity peaks appear after subsequent reduction treatment.

[0051] As can be seen from the SEM of LCCT1200 (e.g.) Figure 2 As shown, cubic CeO2 particles are uniformly distributed on the perovskite surface and have a considerable coverage. The polyhedral CeO2 cubes form a well-nested interface structure on the matrix, without visible cracks or voids. This favorable interface structure not only enhances the anti-aggregation stability of the precipitated particles but also promotes the interdiffusion of ions between the two phases. Figure 3 The SEM image from the LCCT1200-R shows that cubic CeO2 phase and fine metallic Co nanoparticles appear simultaneously.

[0052] Figure 4 The EDS image from the LCCT1200 shows that La, Co, and Ti are uniformly distributed without obvious aggregation. Furthermore, only Ce exhibits significant granular aggregation, corresponding to... Figure 2 Based on the cubic phase particles observed in the SEM and the data above, it can be determined that after annealing, Ce elements precipitated on the sample surface in the form of oxides. Figure 5The EDS spectrum of the LCCT1200-R shows that most elements, La and Ti, are uniformly distributed on the surface of the bulk phase of the sample. La and Ti elements are not present in the precipitated particles. A large amount of nano-Co metal is precipitated on the perovskite surface. At the same time, it can be seen that the precipitation of CeO2 did not disappear due to the treatment of the reducing atmosphere. CeO2 and Co metal will coexist as catalysts on the perovskite surface.

[0053] Example 2

[0054] Perovskite material La was prepared according to the method in Example 1. 0.75 Ce 0.05 Co 0.5 Ti 0.5 O 3-δ The difference is that in step (4) of this embodiment, the temperature is increased at a rate of 1℃ / min and kept at 900℃ for 2h to obtain annealed LCCT, and then the reduction treatment in step (5) is performed.

[0055] Example 3

[0056] Perovskite material La was prepared according to the method in Example 1. 0.75 Ce 0.05 Co 0.5 Ti 0.5 O 3-δ The difference is that in step (4) of this embodiment, the temperature is increased at a rate of 1℃ / min and kept at 1300℃ for 2h to obtain annealed LCCT, and then the reduction treatment in step (5) is performed.

[0057] Example 4

[0058] Perovskite material La was prepared according to the method in Example 1. 0.75 Ce 0.05 Co 0.5 Ti 0.5 O 3-δ The difference is that in step (4) of this embodiment, the temperature is increased at a rate of 1℃ / min and kept at 1200℃ for 12h to obtain annealed LCCT, and then the reduction treatment in step (5) is performed.

[0059] Example 5

[0060] Perovskite material La was prepared according to the method in Example 1. 0.75 Ce 0.05 Co 0.5 Ti 0.5 O 3-δThe difference is that in step (4) of this embodiment, the temperature is increased at a rate of 2℃ / min and kept at 1200℃ for 2h to obtain annealed LCCT, and then the reduction treatment in step (5) is performed.

[0061] Example 6

[0062] The perovskite material La was prepared according to the following method. 0.75 Ce 0.1 Co 0.5 Ti 0.5 O 3-δ :

[0063] (1) Synthesis of La by sol-gel method 0.75 Ce 0.1 Co 0.5 Ti 0.5 O 3-δ According to the stoichiometric ratio of the chemical formula, analytical grade lanthanum nitrate, cerium nitrate, cobalt nitrate, and tetrabutyl titanate were weighed and added to N,N-dimethylformamide (hereinafter referred to as DMF) solution. Citric acid was weighed according to the mass ratio of metal ions to citric acid = 1:1.5 and added to DMF solution. The liquid was stirred evenly with a magnetic stirrer and heated to 80°C to obtain a gel.

[0064] (2) The gel obtained in step (1) is heated to 360°C on a heating table for pre-sintering to obtain a dry gel;

[0065] (3) The dry gel obtained in step (2) is placed in a muffle furnace and heated to 1400°C at a heating rate of 5°C / min. After holding at the temperature for 12 hours, it is cooled to room temperature at a cooling rate of 5°C / min to obtain LCCT powder.

[0066] (4) The LCCT powder obtained in step (3) is placed in a muffle furnace for annealing. The temperature is increased at a rate of 1℃ / min and held at 1200℃ for 2h to obtain annealed LCCT, which is denoted as LCCT1200.

[0067] (5) The LCCT1200 obtained in step (4) is placed in a reducing atmosphere of 850℃ and 5%H2-95%N2 for reduction treatment. The resulting product is denoted as LCCT1200-R.

[0068] (6) The LCCT1200-R powder obtained in step (5) is placed in a planetary ball mill and ball-milled for 48 hours. The ball-milled product is dried and sieved to obtain the final perovskite material powder.

[0069] Example 7

[0070] The perovskite material La was prepared according to the following method. 0.8 Ce 0.05Co 0.5 Ti 0.5 O 3-δ :

[0071] (1) Synthesis of La by sol-gel method 0.8 Ce 0.05 Co 0.5 Ti 0.5 O 3-δ According to the stoichiometric ratio of the chemical formula, analytical grade lanthanum nitrate, cerium nitrate, cobalt nitrate, and tetrabutyl titanate were weighed and added to N,N-dimethylformamide (hereinafter referred to as DMF) solution. Citric acid was weighed according to the mass ratio of metal ions to citric acid = 1:1.5 and added to DMF solution. The liquid was stirred evenly with a magnetic stirrer and heated to 80°C to obtain a gel.

[0072] (2) The gel obtained in step (1) is heated to 360°C on a heating table for pre-sintering to obtain a dry gel;

[0073] (3) The dry gel obtained in step (2) is placed in a muffle furnace and heated to 1400°C at a heating rate of 10°C / min. After holding at the temperature for 12 hours, it is cooled to room temperature at a cooling rate of 10°C / min to obtain LCCT powder.

[0074] (4) The LCCT powder obtained in step (3) is placed in a muffle furnace for annealing. The temperature is increased at a rate of 1℃ / min and held at 1200℃ for 2h to obtain annealed LCCT, which is denoted as LCCT1200.

[0075] (5) The LCCT1200 obtained in step (4) is placed in a reducing atmosphere of 850℃ and 5%H2-95%N2 for reduction treatment. The resulting product is denoted as LCCT1200-R.

[0076] (6) The LCCT1200-R powder obtained in step (5) is placed in a planetary ball mill and ball-milled for 48 hours. The ball-milled product is dried and sieved to obtain the final perovskite material powder.

[0077] Example 8

[0078] The perovskite material La was prepared according to the following method. 0.8 Ce 0.1 Co 0.5 Ti 0.5 O 3-δ :

[0079] (1) Synthesis of La by sol-gel method 0.8 Ce 0.1 Co 0.5 Ti 0.5 O 3-δAccording to the stoichiometric ratio of the chemical formula, analytical grade lanthanum nitrate, cerium nitrate, cobalt nitrate, and tetrabutyl titanate were weighed and added to N,N-dimethylformamide (hereinafter referred to as DMF) solution. Citric acid was weighed according to the mass ratio of metal ions to citric acid = 1:1.5 and added to DMF solution. The liquid was stirred evenly with a magnetic stirrer and heated to 80°C to obtain a gel.

[0080] (2) The gel obtained in step (1) is heated to 360°C on a heating table for pre-sintering to obtain a dry gel;

[0081] (3) The dry gel obtained in step (2) is placed in a muffle furnace and heated to 1400°C at a heating rate of 8°C / min. After holding at the temperature for 5 hours, it is cooled to room temperature at a cooling rate of 8°C / min to obtain LCCT powder.

[0082] (4) The LCCT powder obtained in step (3) is placed in a muffle furnace for annealing. The temperature is increased at a rate of 1℃ / min and held at 1200℃ for 2h to obtain annealed LCCT, which is denoted as LCCT1200.

[0083] (5) The LCCT1200 obtained in step (4) is placed in a reducing atmosphere of 850℃ and 5%H2-95%N2 for reduction treatment. The resulting product is denoted as LCCT1200-R.

[0084] (6) The LCCT1200-R powder obtained in step (5) is placed in a planetary ball mill and ball-milled for 48 hours. The ball-milled product is dried and sieved to obtain the final perovskite material powder.

[0085] Comparative Example 1

[0086] Perovskite material La was prepared according to the method in Example 1. 0.75 Ce 0.05 Co 0.5 Ti 0.5 O 3-δ The difference is that in step (4) of this comparative example, the temperature is increased at a rate of 1℃ / min and held at 800℃ for 2h to obtain annealed LCCT, and then the reduction treatment in step (5) is performed.

[0087] Comparative Example 2

[0088] Perovskite material La was prepared according to the method in Example 1. 0.75 Ce 0.05 Co 0.5 Ti 0.5 O 3-δThe difference is that in step (4) of this comparative example, the temperature is increased at a rate of 1℃ / min and held at 1400℃ for 2h to obtain annealed LCCT, and then the reduction treatment in step (5) is performed.

[0089] Comparative Example 3

[0090] Perovskite material La was prepared according to the method in Example 1. 0.75 Ce 0.05 Co 0.5 Ti 0.5 O 3-δ The difference is that in step (4) of this comparative example, the temperature is increased at a rate of 1℃ / min and held at 1200℃ for 15h to obtain annealed LCCT, and then the reduction treatment in step (5) is performed.

[0091] Comparative Example 4

[0092] Perovskite material La was prepared according to the method in Example 1. 0.75 Ce 0.05 Co 0.5 Ti 0.5 O 3-δ The difference is that in step (4) of this comparative example, the temperature is increased at a rate of 3℃ / min and held at 1200℃ for 2h to obtain annealed LCCT, and then the reduction treatment in step (5) is performed.

[0093] Comparative Example 5

[0094] The perovskite material La was prepared according to the following method. 0.75 Ce 0.05 Co 0.5 Ti 0.5 O 3-δ :

[0095] (1) Synthesis of La by sol-gel method 0.75 Ce 0.05 Co 0.5 Ti 0.5 O 3-δ According to the stoichiometric ratio of the chemical formula, analytical grade lanthanum nitrate, cerium nitrate, cobalt nitrate, and tetrabutyl titanate were weighed and added to N,N-dimethylformamide (hereinafter referred to as DMF) solution. Citric acid was weighed according to the mass ratio of metal ions to citric acid = 1:1.5 and added to DMF solution. The liquid was stirred evenly with a magnetic stirrer and heated to 80°C to obtain a gel.

[0096] (2) The gel obtained in step (1) is heated to 360°C on a heating table for pre-sintering to obtain a dry gel;

[0097] (3) The dry gel obtained in step (2) is placed in a muffle furnace and heated to 1400°C at a heating rate of 8°C / min. After holding at the temperature for 12 hours, it is cooled to room temperature at a cooling rate of 8°C / min to obtain LCCT powder.

[0098] (4) The LCCT powder obtained in step (3) is placed in a reducing atmosphere of 850℃ and 5%H2-95%N2 for reduction treatment. The resulting product is denoted as LCCT1200-R.

[0099] (5) The LCCT1200-R powder obtained in step (4) is placed in a planetary ball mill and ball-milled for 48 hours. The ball-milled product is dried and sieved to obtain the final perovskite material powder.

[0100] Comparative Example 6

[0101] Perovskite material La was prepared according to the method in Example 1. 0.75 Ce 0.05 Co 0.5 Ti 0.5 O 3-δ The difference is that the temperature for heat treatment of the dry gel in step (3) of this comparative example is 1300℃. Specifically, step (3) of this comparative example is as follows:

[0102] The dry gel obtained in step (2) was placed in a muffle furnace and heated to 1300°C at a heating rate of 8°C / min. After holding at this temperature for 12 hours, it was cooled to room temperature at a cooling rate of 8°C / min to obtain LCCT powder.

[0103] Experimental Example

[0104] The perovskite material powders prepared in Examples 1-8 and Comparative Examples 1-6 were placed in a 5% H2-95% N2 atmosphere at 750℃-850℃, and their respective symmetric cell polarization impedances (Ro) were analyzed. p The test results are shown in Table 1.

[0105] Table 1. Test results of symmetric cell polarization impedance for various perovskite materials

[0106]

[0107] In Table 1, the annealing temperature in Comparative Example 1 was too low, resulting in no cerium oxide precipitation during the annealing stage; the annealing temperature in Comparative Example 2 was too high, causing the cerium oxide precipitated in situ during the annealing stage to reintegrate into the crystal lattice, resulting in no cerium oxide precipitation in the final product; the annealing time in Comparative Example 3 was too long, resulting in very little cerium oxide precipitation during the annealing stage; the heating rate in Comparative Example 4 was too fast, resulting in almost no cerium oxide precipitation during the annealing stage; and Comparative Example 5 did not undergo high-temperature annealing, which is equivalent to no cerium oxide precipitation during the annealing stage. Therefore, the detection results of Comparative Examples 1-5 are similar.

[0108] In Comparative Example 6, the heat treatment temperature was 1300°C. Cerium ions were not incorporated into the perovskite oxide lattice during the heat treatment stage, but existed in the form of oxides. That is, the product obtained in Comparative Example 6 is a mechanical composite of cerium oxide and perovskite oxide. Since cerium ions are not incorporated into the lattice in this product, the amount of cerium oxide is higher than that in the product obtained in Example 1. Therefore, the polarization impedance test results of the symmetric cell obtained in Comparative Example 6 are slightly better than those of the product obtained in Example 1. However, it is expected that, since the cerium oxide and perovskite oxide in the product obtained in Comparative Example 6 are mechanically composited, the stability of the battery prepared using this material will be much worse than that prepared using the product obtained in Example 1.

[0109] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a perovskite material, characterized in that, Includes the following steps: Step S1: The perovskite oxide powder is heated to 900-1300℃ for annealing to obtain annealed perovskite oxide powder; wherein the perovskite oxide is an ABO3 type perovskite oxide doped with cerium ions at the A site and transition metal ions at the B site, and the cerium ions are doped in the crystal lattice of the perovskite oxide. Step S2: The annealed perovskite oxide powder is placed in a reducing atmosphere for heat treatment.

2. The preparation method according to claim 1, characterized in that, In step S1, when heating the perovskite oxide powder, the heating rate is 1-2 °C / min; And / or, the annealing time is 2 to 12 hours.

3. The preparation method according to claim 1, characterized in that, In step S1, the transition metal ion includes at least one of cobalt ion, nickel ion, iron ion, copper ion and titanium ion; And / or, the A-site of the perovskite oxide is at least one of La, Pr, Sr, Ba and Sm; And / or, the B site of the perovskite oxide is at least one of Ti, Fe, Co, Ni and Cu.

4. The preparation method according to claim 3, characterized in that, The perovskite oxide is La 1-x-y Ce y Co z Ti 1- z O 3-δ Where x takes values ​​from 0 to 0.3, y takes values ​​from 0.01 to 0.1, and z takes values ​​from 0 to 0.5, and the value of z is not 0.

5. The preparation method according to claim 1, characterized in that, In step S2, the reducing atmosphere includes at least one of a nitrogen-hydrogen mixture, a nitrogen-carbon mixture, and a hydrocarbon mixture; And / or, the volume ratio of hydrogen in the reducing atmosphere is 5-20%; And / or, the conditions for the heat treatment include: a temperature of 750–850°C and a time of 2–10 hours.

6. The preparation method according to claim 1, characterized in that, The preparation method of the perovskite oxide includes the sol-gel method, and the preparation process of the perovskite oxide includes: According to the stoichiometric ratio, the raw materials used to generate the perovskite oxide are added to the solvent, and then citric acid is added according to the mass ratio of metal ions:citric acid = 1: (1~2). The mixture is stirred and heated at 70~100℃ to obtain a gel. The gel was heated to 320–360°C for pre-sintering to obtain a dry gel. The dry gel is heated to a temperature not lower than 1400°C at a heating rate of 5–10°C / min, kept at that temperature for 5–20 h, and then cooled to room temperature at a cooling rate of 5–10°C / min.

7. The preparation method according to claim 6, characterized in that, The perovskite oxide is La 1-x- y Ce y Co z Ti 1-z O 3-δ In this case, the raw materials used to react and generate the perovskite oxide include lanthanum nitrate, cerium nitrate, cobalt nitrate, and tetrabutyl titanate.

8. A perovskite material, characterized in that, The perovskite material is prepared by the preparation method according to any one of claims 1 to 7, and the perovskite material comprises perovskite oxide and cerium oxide and transition metal particles that are sequentially precipitated in situ from the perovskite oxide.

9. A cathode for a solid oxide electrolytic cell, characterized in that, Includes the perovskite material as described in claim 8.

10. A solid oxide electrolytic cell, characterized in that, It includes the perovskite material of claim 8 or the solid oxide electrolytic cell cathode of claim 9.

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