Composite oxygen electrode material and preparation method thereof

Abstract

The invention discloses a composite oxygen electrode material and a preparation method thereof. The preparation method comprises the following steps: S1, preparing a precursor solution from tetrabutyl titanate; s2, dipping the precursor solution into an oxygen electrode skeleton; s3, carrying out drying treatment on the impregnated oxygen electrode skeleton; and S4, in an atmosphere containing water vapor, carrying out heat treatment on the dried oxygen electrode skeleton to hydrolyze tetrabutyl titanate in situ, and forming a nano TiO2 catalyst layer on the oxygen electrode skeleton to obtain the composite oxygen electrode material. According to the preparation method disclosed by the invention, one-step hydrolysis reaction is used for replacing repeated dipping-high-temperature sintering circulation in a traditional process, so that the process is simplified, the cost is reduced, meanwhile, a high-activity nano TiO2 catalyst layer is uniformly constructed on an oxygen electrode framework, and further, the high-activity and high-stability composite oxygen electrode material is obtained.

Description

Technical Field

[0001] This invention belongs to the field of solid oxide battery technology, specifically relating to a composite oxygen electrode material and its preparation method. Background Technology

[0002] Reversible solid oxide cells (RSOCs) are all-solid-state energy conversion devices. In power generation mode, they can directly convert the chemical energy in fuel into electrical energy through electrochemical processes; in electrolysis mode, they can utilize excess renewable energy to electrolyze water to produce pure hydrogen for energy storage. RSOCs have advantages such as high energy conversion efficiency, low emissions, and no need for precious metal catalysts. Based on the different conducting ions in the electrolyte, RSOCs are mainly divided into oxygen ion conducting reversible solid oxide cells (O-RSOCs) and proton conducting reversible solid oxide cells (H-RSOCs), the latter often referred to as reversible protonic ceramic cells (RPCCs). Traditional O-RSOCs rely on the conduction of oxygen ions in the electrolyte and typically require operation at relatively high temperatures (≥700℃) to ensure sufficient ionic conductivity and reactivity. However, the high operating temperature places stringent requirements on sealing technology and long-term stability, increasing system complexity and manufacturing costs, which to some extent limits their commercialization. In contrast, RPCCs use protons as charge carriers, and their electrolyte materials maintain high ionic conductivity at lower temperatures, allowing operating temperatures to be reduced to below 700°C. This brings several technical advantages, such as simplifying the sealing process and improving sealing reliability; reducing thermal stress and interfacial reactions between battery components at high temperatures, thus improving interfacial compatibility and structural stability; and improving system thermal stability and start-up flexibility. Therefore, RPCCs are considered one of the important technical routes for achieving mid-temperature, high-performance, long-life reversible solid oxide battery systems.

[0003] However, the decrease in operating temperature also brings new challenges. Most critically, the drop in temperature significantly slows down the oxygen reduction / oxygen evolution reaction kinetics of the oxygen electrode, leading to a sharp increase in the polarization resistance of the oxygen electrode. This has become a major bottleneck limiting the performance improvement of low- and medium-temperature RPCCs. Therefore, developing oxygen electrode materials with high catalytic activity at low and medium temperatures is key to advancing the low-temperature development of PCFCs. To improve oxygen electrode performance, researchers have widely adopted nano-modification strategies, such as impregnation, self-assembly, and atomic layer deposition. Among these, impregnation is considered the most economical, effective, and commercially viable modification technique due to its simplicity, low cost, and ability to effectively construct highly active nanocatalytic layers on the surface of framework structures. However, traditional impregnation processes have significant limitations. To achieve uniform catalyst distribution and sufficient loading, multiple repeated impregnation-heat treatment cycles are usually required. This lengthy process results in low production efficiency and high energy consumption. Furthermore, repeated heat treatment can lead to problems such as excessive sintering and growth of nanoparticles, thereby weakening the advantages of nanostructures. Summary of the Invention

[0004] The purpose of this invention is to provide a composite oxygen electrode material and its preparation method, which replaces the repeated impregnation-high temperature sintering cycle in the traditional process with a one-step hydrolysis reaction. This simplifies the process and reduces costs while uniformly constructing a highly active nano-TiO2 catalytic layer on the oxygen electrode framework, thereby obtaining a highly active and stable composite oxygen electrode material.

[0005] To achieve the above objectives, the present invention provides a method for using a composite oxygen electrode material, comprising the following steps: S1. Tetrabutyl titanate was used to prepare the precursor solution; S2. The precursor solution is immersed in the oxygen electrode framework; S3. Dry the impregnated oxygen electrode frame. S4. In an atmosphere containing water vapor, the dried oxygen electrode framework is heat-treated to hydrolyze tetrabutyl titanate in situ, forming a nano-TiO2 catalytic layer on the oxygen electrode framework, thus obtaining a composite oxygen electrode material.

[0006] Preferably, in step S1, the precursor solution is a solution formed by dissolving tetrabutyl titanate in an organic solvent, wherein the organic solvent is at least one of anhydrous ethanol and isopropanol.

[0007] Preferably, in step S1, the concentration of tetrabutyl titanate in the precursor solution is 0.2 mol / L. -1 Up to 0.3 mol / L -1 .

[0008] Preferably, in step S3, the oxygen electrode skeleton is placed in a drying oven and dried at 50-80°C for 5-10 minutes.

[0009] Preferably, in step S4, the water vapor atmosphere is generated by bubbling a carrier gas through hot water at 25-50°C, the carrier gas being air, nitrogen, or argon, and the water vapor content being 3%.

[0010] Preferably, in step S4, the heat treatment temperature is 50-80℃ and the treatment time is 1-2 hours.

[0011] Preferably, the oxygen electrode framework is a perovskite oxide, specifically La. 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ La 0.6 Sr 0.4 CoO 3-δ PrBaCo2O 5+δ At least one of them, δ This represents the content of oxygen vacancies.

[0012] The present invention also proposes a composite oxygen electrode material, which is prepared by the above-described method.

[0013] Preferably, the TiO2 particles in the nano-TiO2 catalyst layer have a size of less than 100 nm.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: The preparation method of this invention simplifies the cumbersome multiple impregnation-high temperature sintering cycles into a single impregnation and a simple water vapor treatment through a one-step impregnation-hydrolysis process, which greatly reduces the process steps and energy consumption. At the same time, by utilizing the in-situ hydrolysis reaction of tetrabutyl titanate, a highly active nano-TiO2 catalyst layer is uniformly constructed on the oxygen electrode framework, which enhances the electrochemical performance of the proton ceramic fuel cell.

[0015] The preparation method of this invention replaces the repeated impregnation-high temperature sintering cycle in the traditional process with a one-step hydrolysis reaction, thereby simplifying the process and reducing costs while obtaining a highly active and stable composite oxygen electrode material. Attached Figure Description

[0016] Figure 1 This is the X-ray diffraction (XRD) pattern of the composite oxygen electrode material in this invention; Figure 2 This is a scanning electron microscope (SEM) image of the composite oxygen electrode material in this invention; Figure 3 This is the energy dispersive spectroscopy (EDS) diagram of the composite oxygen electrode material in this invention; Figure 4 This is a comparison diagram of the polarization impedance of the composite oxygen electrode material and the oxygen electrode framework in this invention. Detailed Implementation

[0017] The invention will now be further described with reference to the accompanying drawings.

[0018] Example 1

[0019] Preparation of oxygen electrode framework: (1) PrBaCo2O was prepared by sol-gel method 5+δ (PBC) powder was prepared by dissolving Pr(NO3)3·6H2O, Ba(NO3)2, and Co(NO3)2·6H2O in deionized water according to stoichiometric ratio. Citric acid and ethylenediaminetetraacetic acid were added as complexing agents at a molar ratio of 1:2:1 for metal ions, citric acid, and ethylenediaminetetraacetic acid. The pH was adjusted to about 8 with ammonia water. After heating to form a gel, the mixture was transferred to a high-temperature oven and burned at 300 °C to obtain precursor powder. The precursor powder was then ground and calcined at 1100 °C to finally obtain pure-phase PBC perovskite powder.

[0020] (2) PBC perovskite powder and organic binder (containing 5% wt ethyl cellulose terpineol) are mixed at a mass ratio of 1:1 and ground to form a uniform slurry. The slurry is then coated onto BaZr using screen printing. 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3+δ On a (BZCYYb) proton conductor electrolyte sheet, an oxygen electrode framework with a porous structure is formed by sintering at 1000 °C for 3 h.

[0021] Precursor solution preparation: Tetrabutyl titanate was slowly added dropwise to anhydrous ethanol in dry air while continuously stirring magnetically to prepare a solution with a concentration of 0.25 mol / L. -1 A clear and transparent precursor solution.

[0022] Impregnation: Using a microsyringe, accurately measure 1-5 µL of the above precursor solution and uniformly drop it onto the surface of the porous oxygen electrode framework. The precursor solution quickly and uniformly penetrates the entire porous network.

[0023] The impregnated electrode was placed in a drying oven and dried at 50 °C for 10 min to slowly and thoroughly remove the ethanol solvent, so that tetrabutyl titanate was evenly distributed on the porous surface of the oxygen electrode skeleton.

[0024] Steam treatment: The dried oxygen electrode framework was collected and placed in a test furnace. 3% H2O air was introduced into the oxygen electrode side of the furnace, with the total gas flow rate controlled at 100 sccm. The oxygen electrode framework was treated at 80℃ for 2 hours in a steam-containing atmosphere. During this process, tetrabutyl titanate underwent a complete in-situ hydrolysis reaction with steam: Ti(OC4H9)4 + 2H2O → TiO2 + 4C4H9OH, generating TiO2 nanoparticles. Subsequently, the temperature was increased to the test temperature of 700℃ at a rate of 3℃ / min. During the heating process, the nano-TiO2 formed a more stable bond with the oxygen electrode framework. During the test, a nano-TiO2 catalytic layer can be directly generated in situ on the oxygen electrode framework, thus preparing a composite oxygen electrode material with high catalytic activity.

[0025] Characterization and electrochemical performance tests were performed on the composite oxygen electrode in Example 1: (1) Structural characterization: Figure 1 The X-ray diffraction (XRD) pattern showed characteristic peaks of the anatase phase TiO2 near 26°. Figure 2 Scanning electron microscopy (SEM) images revealed that the surface and junctions of the composite oxygen electrode material's framework particles were uniformly covered with a layer of fine nanoparticles, with a size distribution ranging from 10 to 30 nm. Combined with energy dispersive spectroscopy (EDS) surface scanning analysis, this confirmed the uniform distribution of Ti element in the framework region of the composite oxygen electrode material.

[0026] (2) Electrochemical performance: A symmetrical cell was constructed by combining the composite oxygen electrode material (PBC-TiO2) with the BZCYYb electrolyte sheet (structure: PBC-TiO2 | BZCYYb electrolyte | PBC-TiO2). Electrochemical impedance spectroscopy measured at 700 °C in air showed that its area-to-polarization impedance was as low as 0.06 Ω cm⁻¹. -2 The polarization impedance of the unmodified oxygen electrode framework (PBC) symmetric cell under the same conditions is 0.1 Ω cm. -2 The polarization impedance decreased by about 40%, demonstrating a significant improvement in oxygen reduction activity.

[0027] The above are merely preferred embodiments of the present invention and do not constitute any limitation on the present invention. Any equivalent substitutions or modifications made by those skilled in the art to the technical solutions and content disclosed in the present invention without departing from the scope of the present invention shall be deemed to have remained within the protection scope of the present invention.

Claims

1. A method for preparing a composite oxygen electrode material, characterized in that, Includes the following steps: S1. Tetrabutyl titanate was used to prepare the precursor solution; S2. The precursor solution is immersed in the oxygen electrode framework; S3. Dry the impregnated oxygen electrode frame. S4. In an atmosphere containing water vapor, the dried oxygen electrode framework is heat-treated to hydrolyze tetrabutyl titanate in situ, forming a nano-TiO2 catalytic layer on the oxygen electrode framework, thus obtaining a composite oxygen electrode material.

2. The method for preparing the composite oxygen electrode material according to claim 1, characterized in that, In step S1, the precursor solution is a solution formed by dissolving tetrabutyl titanate in an organic solvent, wherein the organic solvent is at least one of anhydrous ethanol and isopropanol.

3. The method for preparing the composite oxygen electrode material according to claim 2, characterized in that, In step S1, the concentration of tetrabutyl titanate in the precursor solution is 0.2 mol / L. -1 Up to 0.3 mol L -1 .

4. The method for preparing the composite oxygen electrode material according to claim 1, characterized in that, In step S3, the oxygen electrode skeleton is placed in a drying oven and dried at 50-80℃ for 5-10 minutes.

5. The method for preparing the composite oxygen electrode material according to claim 1, characterized in that, In step S4, the water vapor atmosphere is generated by bubbling a carrier gas through hot water at 25-50°C. The carrier gas is air, nitrogen, or argon, and the water vapor content is 3%.

6. The method for preparing the composite oxygen electrode material according to claim 1, characterized in that, In step S4, the heat treatment temperature is 50-80℃ and the treatment time is 1-2 hours.

7. The method for preparing the composite oxygen electrode material according to claim 1, characterized in that, The oxygen electrode framework is a perovskite oxide, specifically La. 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ La 0.6 Sr 0.4 CoO 3-δ PrBaCo2O 5+δ At least one of them, δ This represents the content of oxygen vacancies.

8. A composite oxygen electrode material, characterized in that, It is prepared by any one of claims 1-7.

9. The composite oxygen electrode material according to claim 8, characterized in that, The TiO2 particles in the nano-TiO2 catalyst layer are smaller than 100 nm in size.

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