A roughened solid oxide electrolyte supported single cell and a method for preparing the same

Abstract

The present invention belongs to the technical field of solid oxide single cells, and relates to a roughened solid oxide electrolyte supported single cell and a preparation method thereof, wherein the single cell comprises a lanthanum strontium magnesium gallium oxide electrolyte sheet, the surface of the lanthanum strontium magnesium gallium oxide electrolyte sheet has a microscopic rough structure, and the roughness is 2.5 μm to 3.0 μm; the preparation method comprises the steps of soaking the lanthanum strontium magnesium gallium oxide electrolyte sheet in a sealed container for 15 hours with a prepared etching solution, etching the surface of the lanthanum strontium magnesium gallium oxide electrolyte sheet, so that the surface of the lanthanum strontium magnesium gallium oxide electrolyte sheet forms a surface morphology with a microscopic rough structure; the preparation method of the present invention has the advantages of simple process, strong controllability and low cost, the prepared single cell has a rough and uniform surface, the electrode is firmly attached, and the electrochemical performance is excellent, and the single cell can be widely used in the preparation of solid oxide electrolytic cells and related fields.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid oxide electrolyte supported single cells, and in particular relates to a roughened solid oxide electrolyte supported single cell and a preparation method thereof. Background Art

[0002] In SOEC, the contact quality of the electrolyte and electrode interface is a key factor in determining its performance and stability. The quality of the interface contact directly affects the electrochemical reaction rate, oxygen ion conductivity and overall energy conversion efficiency. However, most of the current research on SOEC focuses on the design and development of high-performance electrode materials, while relatively few studies have been conducted on the characteristics of the electrolyte interface. The traditional electrolyte interface is usually a smooth planar structure. This design significantly limits the actual contact surface area between the electrolyte and the electrode, resulting in insufficient interfacial reaction activity, which restricts the improvement of the overall electrochemical performance. In addition, the shortcomings of traditional methods in electrolyte interface modification are mainly due to the complex preparation process, high cost and high technical difficulty. These factors have prevented electrolyte interface engineering from becoming a research focus. In order to overcome this technical difficulty and deeply reveal the mechanism of interface design to improve electrolytic performance, the present invention proposes a new method for acid corrosion modification of LSGM electrolyte surface based on the interface engineering strategy. This method significantly increases the roughness of the electrolyte surface, reduces the thickness, and repairs high-temperature annealing damage by simple acid treatment. After the electrolyte interface is roughened, the chemical bonding between the electrolyte and the electrode is enhanced, and the electrochemical performance is significantly improved. Roughening the electrolyte interface provides a new perspective for improving the performance of SOEC CO2 electrolysis, solves the problems of poor contact quality between traditional electrolytes and electrodes and insufficient interfacial active sites, optimizes the ion and electron transmission pathways, significantly improves the performance of SOEC CO2 electrolysis, and is beneficial to CO2 emission reduction and resource utilization. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a roughened solid oxide electrolyte supported single cell and a preparation method thereof.

[0004] In order to achieve the purpose of the present invention, the present invention is implemented by adopting the following technical solutions.

[0005] A method for preparing a roughened solid oxide electrolyte supported single cell comprises the following steps:

[0006] S1. Adding binder powder to the ground lanthanum strontium magnesium gallium oxide powder and continuing to grind until it is in a floating state to obtain a basic raw material;

[0007] S2, preparing a lanthanum strontium magnesium gallium oxide electrolyte body by dry pressing the basic raw material;

[0008] S3, placing the lanthanum strontium magnesium gallium oxide electrolyte body in a high-temperature sintering furnace, sintering according to a preset temperature rising process, and maintaining it for 4-6 hours when the target temperature is reached. After the sintering is completed, the temperature of the lanthanum strontium magnesium gallium oxide electrolyte sheet obtained by sintering is reduced to room temperature by natural cooling or a preset cooling process; wherein the target temperature is 1450°C;

[0009] S4, soaking the lanthanum strontium magnesium gallium oxide electrolyte sheet in a sealed container by completely immersing it in the prepared etching solution for 10 to 20 hours, etching the surface of the lanthanum strontium magnesium gallium oxide electrolyte sheet so that the surface of the lanthanum strontium magnesium gallium oxide electrolyte sheet forms a surface morphology with a microscopic rough structure, that is, increasing the roughness of the surface of the lanthanum strontium magnesium gallium oxide electrolyte sheet. After the etching is completed, the lanthanum strontium magnesium gallium oxide electrolyte sheet with a rough surface morphology is taken out from the etching solution, and ultrasonically cleaned with deionized water to remove the etching solution and etching products remaining on the surface of the lanthanum strontium magnesium gallium oxide electrolyte sheet. After cleaning, drying is performed by natural drying or low-temperature drying; wherein the etching solution is an acidic solution, and the acidic solution is a mixture of concentrated nitric acid and concentrated hydrochloric acid in a volume ratio of 1:3;

[0010] S5. Use the prepared electrode slurry to evenly coat the surface of the dried lanthanum strontium magnesium gallium oxide electrolyte sheet. After coating, place the lanthanum strontium magnesium gallium oxide electrolyte sheet coated with the electrode slurry in an air atmosphere and perform high-temperature calcination treatment to allow the electrode slurry to undergo an interfacial reaction with the electrolyte to form a three-phase interface, thereby constructing a rough solid oxide electrolyte-supported single cell.

[0011] As a preferred embodiment of the present invention, the mass ratio of the lanthanum strontium magnesium gallium oxide powder to the binder powder is 5:1.

[0012] As a preferred embodiment of the present invention, the adhesive is 1 wt% PVA in powder mass.

[0013] As a preferred embodiment of the present invention, the dry pressing process comprises the following steps:

[0014] S41, filling the lanthanum strontium magnesium gallium oxide powder into the mold layer by layer by using a layered filling method, and using a scraper to evenly scrape each layer;

[0015] S42, after the filling is completed, apply a pressing pressure of 200MP to 300MP and maintain the pressure for 1 minute;

[0016] S43. After the pressure maintenance is completed, the pressure is slowly reduced at a rate of 20-30MP / s until it is completely released;

[0017] S44. After release, the compact in the mold is gently demolded to obtain a lanthanum strontium magnesium gallium oxide electrolyte body.

[0018] As a preferred embodiment of the present invention, the temperature rise process adopts a gradual temperature rise mode, gradually raising the temperature to 200°C at a rate of 1°C / min, and then raising the temperature to the target sintering temperature of 1450°C at a rate of 3°C / min.

[0019] As a preferred embodiment of the present invention, the electrode slurry is prepared by mixing electrode powder LSCF and a binder in a mass ratio of 2:3, placing the mixture in a mortar, and grinding the mixture until the mixture is evenly dispersed and has an appropriate viscosity; wherein the binder is formed by mixing 6% by mass ethyl cellulose and 94% by mass pine alcohol.

[0020] As a preferred embodiment of the present invention, the process conditions of high-temperature calcination are as follows: the calcination temperature is set at 1000° C. and the holding time is 3 hours.

[0021] As a preferred embodiment of the present invention, the optimized retention time is 5 hours.

[0022] A single cell supported by a roughened solid oxide electrolyte comprises a lanthanum strontium magnesium gallium oxide electrolyte sheet, wherein the surface of the lanthanum strontium magnesium gallium oxide electrolyte sheet has a microscopic rough structure with a roughness of 2.5 μm to 3.0 μm. Beneficial Effects

[0023] The preparation method of the present invention has the advantages of simple process, strong controllability and low cost. The prepared single cell has a rough and uniform surface, firm electrode adhesion and excellent electrochemical performance, and can be widely used in the preparation of solid oxide electrolytic cells and related fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Characterize the surface modification of the electrolyte to improve the contact quality between the electrode and the electrolyte, where: Figure a shows the electrolyte etching and symmetric battery preparation process; Figure b shows the SEM surface of the untreated electrolyte; Figure c shows the SEM surface of the electrolyte after acid etching for 15 hours; Figure d shows the three-dimensional surface of the untreated electrolyte characterized by confocal microscopy; Figure e shows the three-dimensional surface of the electrolyte after acid etching for 15 hours by confocal microscopy;

[0025] Figure 2 SEM cross section of a single cell with roughened electrolyte support;

[0026] Figure 3 This is the EIS spectrum of a single cell supported by a roughened electrolyte at an open circuit voltage of 800°C in a pure CO2 atmosphere;

[0027] Figure 4 The IV curve of a single cell supported by a roughened electrolyte in pure CO2 atmosphere at 800℃;

[0028] Figure 5 To support the long-term stability of single cells using roughened electrolyte at 750°C and 1.2V in pure CO2 atmosphere. DETAILED DESCRIPTION

[0029] The present invention will be further described with reference to the embodiments and the accompanying drawings.

[0030] As embodiment 1 of the present invention, Figure 1 As shown in Figure a, a method for preparing a roughened solid oxide electrolyte supported single cell comprises the following steps:

[0031] Step 1: First, weigh 5 g of commercially prepared lanthanum-doped strontium magnesium gallium oxide (La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 3-δ , referred to as LSGM) powder, and put it in an agate mortar for 1 hour to fully grind it to ensure the uniformity of the powder particle size and its dispersibility. After the grinding is completed, add 1wt% PVA (1g) as a binder, and continue to grind it fully until the material reaches a uniform floating state to ensure that the material has good fluidity and processing performance. This step aims to improve the uniformity and molding performance of the powder through mechanical grinding and the introduction of binders, and provide high-quality basic raw materials for subsequent process steps;

[0032] Step 2, take 0.18g of the treated LSGM powder and place it evenly into a circular mold. Use a layered filling method to fill the powder into the mold layer by layer, and use a scraper to evenly scrape each layer to ensure the uniformity of density during the pressing process. After the filling is completed, a pressing pressure of 250MP is applied and the pressure is maintained for 1 minute to promote close contact and initial bonding between the powder particles. After the pressure is maintained, the pressure is slowly reduced at a predetermined rate until it is completely released to avoid damage to the compact structure or crack formation caused by a sudden drop in stress. Subsequently, the compact in the mold is gently demolded to obtain a preliminarily formed body, which provides the required geometry and structural integrity for subsequent sintering or other processing techniques;

[0033] Step three, place the LSGM electrolyte green sheet formed by dry pressing in a high-temperature sintering furnace and sinter it according to the preset heating curve. The heating process adopts a gradual heating mode, and the temperature is gradually increased to 200°C at a rate of 1°C / minute, and then the temperature is increased to the target sintering temperature of 1450°C at a rate of 3°C / minute, and maintained at the target temperature for 5 hours to ensure that the interior of the green body is fully densified and microscopic defects are eliminated. During the sintering process, the uniformity of the temperature field and the holding time are precisely controlled to ensure that the thickness of the electrolyte sheet is uniform, the interior is dense, the surface is smooth and the structure is stable. The optimized sintering process can effectively improve the grain connection quality of the material, reduce the porosity, and form a densified microstructure, thereby significantly improving the mechanical strength and ionic conductivity of the electrolyte sheet. After sintering, the sample is cooled to room temperature by natural cooling or a preset cooling curve, and the sintered electrolyte sheet is quality tested to ensure that it meets the target performance requirements and provides high-quality electrolyte materials with stable performance for subsequent applications. The electrolyte sheet prepared by the above steps has a smooth surface, a dense interior, and a thickness of 230 μm;

[0034] Step 4, prepare a mixed solution of concentrated nitric acid and concentrated hydrochloric acid, measure 10 ml of concentrated nitric acid and 30 ml of concentrated hydrochloric acid in a volume ratio of 1:3, place the two acid solutions in a polytetrafluoroethylene container, and mix them thoroughly to prepare a uniform etching solution. Completely immerse the annealed electrolyte sheet in the above mixed solution, and seal the container to prevent the volatilization of the acidic solution. Maintain the immersion time for 15 hours in a closed environment to fully etch the electrolyte surface to form a surface morphology with a microscopic rough structure, thereby increasing the adhesion and interfacial reaction activity of the electrode material. After etching is completed, remove the electrolyte sheet from the solution and use deionized water for ultrasonic cleaning to remove the residual acidic solution and etching products on the surface to ensure that the surface of the electrolyte sheet is clean. The cleaned electrolyte sheet is naturally dried or low-temperature dried to provide a good surface foundation for subsequent electrode coating and sintering processes;

[0035] Step 5: Mix the commercial electrode powder (LSCF) with a binder formed by mixing 6% ethyl cellulose and 94% pine alcohol in a mass ratio of 2:3, and place it in an agate mortar for full grinding until a uniformly dispersed slurry with appropriate viscosity is formed. The prepared electrode slurry is evenly coated on the surface of the electrolyte treated with acid etching, and the flatness and thickness consistency of the coating are ensured by brushing, so that the electrode material fits tightly with the roughened electrolyte surface to form a stable interface structure. After coating, the sample is placed in an air atmosphere for high-temperature calcination, and the calcination temperature is set to 1000°C and the holding time is 3 hours. During the calcination process, the electrode material reacts with the electrolyte to form a densely bonded three-phase interface (TPB), thereby constructing a single cell structure with LSGM electrolyte as support and LSCF as a symmetrical electrode. The single cell has excellent electrochemical performance and mechanical stability, can meet the use requirements of solid oxide electrolytic cells, and is suitable for related applications in the field of energy conversion and storage.

[0036] As embodiment 2 of the present invention, Figure 1 and Figure 2 As shown, a single cell supported by a roughened solid oxide electrolyte comprises a lanthanum strontium magnesium gallium oxide electrolyte sheet, wherein the surface of the lanthanum strontium magnesium gallium oxide electrolyte sheet has a microscopic rough structure with a roughness of 2.5 μm to 3.0 μm.

[0037] To study the electrochemical performance of the single cell, the anode of the single cell is facing up and sealed in an alumina tube by a ceramic sealant to ensure good airtightness. The experimental device was placed in a heating furnace and the test temperature was adjusted to 800°C. During the high-temperature carbon dioxide electrolysis process, pure carbon dioxide gas (flow rate 20mL / min) was introduced into the cathode side, while the anode side was directly exposed to the ambient air. The electrochemical test was carried out using a Zahner electrochemical workstation to evaluate the performance of the prepared single cell. The electrochemical impedance spectroscopy (EIS) was recorded in the frequency range of 105Hz to 10-1Hz. The current-voltage (IV) curve was obtained by scanning from the open circuit voltage (OCV) to 1.6V at a scan rate of 10mV / s. The long-term stability of the single cell was tested under constant voltage conditions to further verify the electrolysis performance and system stability.

[0038] Through the action of acid etching, the grain interface on the electrolyte surface is broken, and the originally smooth surface is transformed into a rough granular structure. The particles are connected to each other, forming an obvious surface roughness structure. Through this etching method, the roughness of the electrolyte surface is significantly increased, which improves the contact quality between the electrolyte and the LSCF electrode, helps to increase the reaction active sites and improve the efficiency of the electrochemical reaction, such as Figure 1As shown in Figure a. The surfaces of the two electrolytes were further characterized by confocal microscopy (CLSM). By constructing a three-dimensional image, it was observed that the surface undulation of the electrolyte after acid etching increased significantly, as shown in Figure 5. Figure 1 As shown in Figures b and c in the figure. Compared with the unetched electrolyte surface, the surface roughness after acid etching increased significantly from 0.34μm to 2.76μm, and the surface morphology became more complex and irregular. This rough surface feature helps to increase the contact area between the electrode and the electrolyte, thereby promoting charge transfer and electrochemical reactions. The increase in surface roughness means that the interface area between the electrolyte and the electrode is significantly expanded, thereby increasing the adsorption capacity of the reactants and the number of reactive sites, such as Figure 1 As shown in Figures d and e.

[0039] The 155μm electrolyte-electrode interface after acid etching shows significantly different characteristics. Due to the uneven surface, the contact area between the electrolyte and the electrode after etching is significantly increased, and the electrode penetrates into the grooves on the electrolyte surface, forming a tighter interface connection. This improvement not only enhances the mechanical bonding between the electrode and the electrolyte, but also provides more reaction sites for the electrochemical reaction, further improving the overall performance of the single cell, such as Figure 2 shown.

[0040] The EIS spectrum of the roughened electrolyte supported single cell under the open circuit voltage of pure CO2 atmosphere at 800℃ and the IV curve of the roughened electrolyte supported single cell under pure CO2 atmosphere at 800℃, as shown in Figure 3 and Figure 4 The results show that the ohmic impedance of a single cell is 0.135Ω·cm 2 , polarization impedance is 0.075Ω·cm 2 , showing 2.23A / cm at 1.5V 2 Ultra-high current density. At 750℃, 1.2V pure CO2 atmosphere, the roughened electrolyte was used to support the long-term stability of the single cell. The single cell was tested for 110 hours. Figure 5 The results show that the performance decay rate of the acid-etched electrolyte single cell is 22.98%.

[0041] The preferred embodiments of the present invention are described above with reference to the accompanying drawings, but the scope of the rights of the present invention is not limited thereto. Any modification, equivalent substitution and improvement made by a person skilled in the art without departing from the scope and essence of the present invention should be within the scope of the rights of the present invention.

Claims

1. A method for preparing a roughened solid oxide electrolyte supported single cell, characterized in that: The steps include: S1. Adding binder powder to the ground lanthanum strontium magnesium gallium oxide powder and continuing to grind until it is in a floating state to obtain a basic raw material; S2. The basic raw material is made into a lanthanum strontium magnesium gallium oxide electrolyte body by a dry pressing process; wherein the dry pressing process comprises the following steps: S21, filling the lanthanum strontium magnesium gallium oxide powder into the mold layer by layer by using a layered filling method, and using a scraper to evenly scrape each layer; S22, after the filling is completed, apply a pressing pressure of 200MP to 300MP and maintain the pressure for 1 minute; S23. After the pressure is maintained, the pressure is slowly reduced at a rate of 20-30MP / s until it is completely released; S24, after release, gently demolding the compact in the mold to obtain a lanthanum strontium magnesium gallium oxide electrolyte body; S3, placing the lanthanum strontium magnesium gallium oxide electrolyte body in a high-temperature sintering furnace, sintering according to a preset temperature rising process, and when the target temperature is reached, maintaining it for 5 hours. After the sintering is completed, the temperature of the lanthanum strontium magnesium gallium oxide electrolyte sheet obtained by sintering is reduced to room temperature by natural cooling or a preset cooling process; wherein the target temperature is 1450°C; S4, soaking the lanthanum strontium magnesium gallium oxide electrolyte sheet in a sealed container in a completely immersed manner for 15 hours with the prepared etching solution, etching the surface of the lanthanum strontium magnesium gallium oxide electrolyte sheet so that the surface of the lanthanum strontium magnesium gallium oxide electrolyte sheet forms a surface morphology with a microscopic rough structure, that is, increasing the roughness of the surface of the lanthanum strontium magnesium gallium oxide electrolyte sheet. After the etching is completed, the lanthanum strontium magnesium gallium oxide electrolyte sheet with a rough surface morphology is taken out from the etching solution, and ultrasonically cleaned with deionized water to remove the etching solution and etching products remaining on the surface of the lanthanum strontium magnesium gallium oxide electrolyte sheet. After cleaning, drying is performed by natural drying or low-temperature drying; wherein the etching solution is an acidic solution, and the acidic solution is a mixture of concentrated nitric acid and concentrated hydrochloric acid in a volume ratio of 1:3; S5. Use the prepared electrode slurry to evenly coat the surface of the dried lanthanum strontium magnesium gallium oxide electrolyte sheet. After coating, place the lanthanum strontium magnesium gallium oxide electrolyte sheet coated with the electrode slurry in an air atmosphere and perform high-temperature calcination treatment to allow the electrode slurry to undergo an interfacial reaction with the electrolyte to form a three-phase interface, thereby constructing a rough solid oxide electrolyte-supported single cell.

2. The method for preparing a roughened solid oxide electrolyte supported single cell according to claim 1, characterized in that: The mass ratio of the lanthanum strontium magnesium gallium oxide powder to the binder powder is 5:

1.

3. The method for preparing a roughened solid oxide electrolyte supported single cell according to claim 1, characterized in that: The adhesive is 1 wt% PVA in powder form.

4. The method for preparing a roughened solid oxide electrolyte supported single cell according to claim 1, characterized in that: The temperature rise process adopts a stepwise temperature rise mode, and the temperature is gradually raised to 200° C. at a rate of 1° C. / min, and then raised to a target sintering temperature of 1450° C. at a rate of 3° C. / min.

5. The method for preparing a roughened solid oxide electrolyte supported single cell according to claim 1, characterized in that: The electrode slurry is obtained by mixing electrode powder LSCF and a binder in a mass ratio of 2:3, placing the mixture in a mortar, and grinding the mixture until the mixture is evenly dispersed and has a suitable viscosity; wherein the binder is formed by mixing 6% by mass ethyl cellulose and 94% by mass pine alcohol.

6. The method for preparing a roughened solid oxide electrolyte supported single cell according to claim 1, characterized in that: The process conditions of the high temperature calcination are as follows: the calcination temperature is set at 1000° C. and the holding time is 3 hours.

7. The method for preparing a roughened solid oxide electrolyte supported single cell according to claim 1, characterized in that: The single cell comprises a lanthanum strontium magnesium gallium oxide electrolyte sheet, the surface of the lanthanum strontium magnesium gallium oxide electrolyte sheet has a microscopic rough structure with a roughness of 2.5 μm to 3.0 μm.

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