Dust self-settling preparation process of electrolyte film of solid oxide fuel cell

Abstract

The invention relates to the technical field of fuel cells, in particular to a dust self-settling preparation process of an electrolyte film of a solid oxide fuel cell. The dust self-settling preparation process adopts the steps of dry pressing, powder spraying and settling, co-pressing and calcining, the thin solid oxide fuel cell electrolyte film with controllable thickness is prepared, the overall operation is simple, and the process is suitable for preparing various compact and uniform electrolyte films with different thicknesses for electrode-supported batteries; the ion conduction path of the electrolyte material is obviously shortened, and the battery performance can be improved.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and in particular to a dust self-settling preparation process for a solid oxide fuel cell electrolyte film. Background Technology

[0002] Solid oxide fuel cells (SOFCs) are devices that directly convert the chemical energy of fuel into electrical energy at high temperatures (600–1000°C). SOFCs offer several key advantages: high energy conversion efficiency; wide fuel adaptability; low cost as they do not require precious metal catalysts; an all-solid-state structure, improving system safety and operational stability; low greenhouse gas emissions; and broad applicability. Therefore, they have attracted increasing attention. However, the high operating temperatures of existing SOFCs accelerate the interactions and diffusion between battery components during operation, reducing battery life. This also places higher demands on the performance of electrode materials and connectors, increasing production costs and impacting the commercial competitiveness of SOFCs.

[0003] A battery's power density and output performance are closely related to its internal resistance. The internal resistance is primarily determined by the bulk resistance of the electrolyte and the three-phase interface resistance between the electrolyte and the anode. High internal resistance negatively impacts both power density and output performance. The thickness of the electrolyte film is one factor influencing the battery's internal resistance. A thinner electrolyte film shortens the ion migration path, reduces bulk resistance, and thus improves ionic conductivity and overall performance; conversely, increased thickness typically leads to increased resistance.

[0004] In existing technologies, powder dry pressing is commonly used to prepare electrolyte films for batteries. A powder sample that has been dried or calcined, ground, and uniformly mixed is placed in a special mold and pressed into a sheet using a tablet press under certain pressure; this process is called powder tableting. To compact the powder into a thin sheet, the powder needs to be evenly spread within the mold first, resulting in a relatively thick electrolyte sheet.

[0005] The applicant's prior patent, "A Method for Preparing a Zirconium-Based Electrolyte Film for Electrolyte-Supported Solid Oxide Fuel Cells" (patent number 2018110564070), prepared a zirconium-based electrolyte film for electrolyte-supported solid oxide fuel cells using a dry pressing / heating / quenching / calcination method. This film is a single-sided roughened YSZ film. The surface roughening treatment of the electrolyte film facilitates close contact between the electrode and the electrolyte, accelerating mass transfer during electrolysis and thus improving the battery performance of the YSZ-supported SOC. Subsequently, through the sublimation method (patent number 2024106546361) and the deliquescence method (patent number 2024106546395), thin and double-sided roughened electrolyte films suitable for electrolyte-supported batteries were prepared. While these patented processes have made progress in the ultrathinning, homogenization, and roughening of zirconium-based electrolyte preparation, they are not suitable for preparing electrolyte films for electrode-supported batteries. Electrolyte films in electrode-supported batteries face challenges in terms of mechanical stability, electrical integrity (no short circuits), and hermeticity (no leakage), and densification is also required.

[0006] Currently, existing technology reports indicate that while emerging thin-film fabrication processes such as ultrasonic atomization pyrolysis, magnetron sputtering, and atomic layer deposition can produce electrolyte films for small-area electrode-supported batteries, the expensive processing equipment and long processing time limit their further large-scale commercial application. As mentioned earlier, the dry pressing method is widely used in laboratories and industry to prepare thick substrates due to its advantages of simple operation, high repeatability, and low cost. However, this method is difficult to use for preparing ultrathin electrolyte layers because the uniform distribution of electrolyte powder on the anode surface is difficult to control. Suk-Won Cha reported the preparation of a bilayer electrolyte film with a thickness of 8 μm of yttrium-stabilized zirconium oxide (YSZ) layer and a thickness of 40 μm of gadolinium-doped cerium oxide (GDC) layer using a simple dry pressing and slurry spraying process (INTERNATIONAL JOURNALOF PRECISION ENGINEERING AND MANUFACTURING-GREEN TECHNOLOGY Vol. 1, No. 2, pp. 95-99, APRIL 2014). However, the electrolyte membrane obtained by this wet preparation method is prone to defects such as pinholes and cracks due to impurities in the slurry and uneven volatilization and decomposition of organic binders and solvents. Therefore, this study developed a simple, rapid, and low-cost preparation method based on dry pressing and powder spraying. Through an innovatively designed powder dry pressing co-molding process, a dense electrolyte membrane for anode-supported SOFCs was successfully prepared. Summary of the Invention

[0007] To overcome the shortcomings of the prior art, this invention provides a dust self-settling preparation process for solid oxide fuel cell electrolyte films. The process is simple to operate and suitable for preparing ultrathin, dense, and uniform electrolyte films of various thicknesses. It shortens the conduction path of the electrolyte material, significantly improves battery performance, and solves the problems existing in the prior art.

[0008] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows: A dust self-settling preparation process for a solid oxide fuel cell electrolyte membrane includes the steps of dry pressing, powder spraying and settling, co-pressing, and calcination.

[0009] Furthermore, the specific steps of the above-mentioned solid oxide fuel cell electrolyte film dust self-settling preparation process are as follows: (1) Grind the electrode material of the fuel cell evenly, and mold it into a sheet to obtain a thin sheet; (2) The electrolyte powder material used to prepare the electrolyte film is sprayed and settled through a powder spraying bottle, so that the electrolyte powder forms dust and settles uniformly on the surface of the thin film obtained in step (1); co-pressing is performed to form a double-layer green body consisting of an electrode and an electrolyte layer; wherein the electrolyte powder material has a particle size of 60-100 mesh. (3) After being placed in a high-temperature muffle furnace for high-temperature calcination, a thin and uniform electrode-supported solid oxide fuel cell electrolyte film is obtained.

[0010] Furthermore, the above steps also include step (4): spraying cathode slurry onto the surface of the electrolyte film obtained in step (3) to prepare a three-layer structure cell with anode / electrolyte / cathode.

[0011] Furthermore, the control conditions for the formation and uniform self-settling of dust in step (2) are as follows: the airflow velocity for the electrolyte powder material is adjusted to 0.2-0.5 m / s, the vertical distance between the outlet of the electrolyte powder material and the electrode sheet is 3-8 cm, and the number of spraying times is 10-20.

[0012] Further, in step (2), the powder spraying bottle includes a 30-50mL airbag powder spraying bottle, with a bent tube at the nozzle outlet end and a cover at the bottom end of the bent tube; during use, the vertical distance between the bottom end of the cover and the electrode sheet is 3-8cm, and the spraying and settling is performed 10-20 times. The 30-50mL airbag powder spraying bottle is a commercially available specification, and the aforementioned improvements achieve the self-settling effect of the electrolyte powder material sprayed out.

[0013] Furthermore, the airbag powder spray bottle includes a silicone airbag, a stainless steel spray pipe and a bottle body, the bent pipe is located at the outlet end of the stainless steel spray pipe, and the bent pipe is a 90° arc transition bent pipe; the cover is a horn cover, and the bottom end of the horn cover is covered with an electrode sheet.

[0014] Furthermore, the bottom inner diameter of the speaker cover is equivalent to the outer edge of the outer electrode sheet.

[0015] Furthermore, the pressure applied to the silicone airbag in a single press is equal to 1 / 2 to 1 of the depth of the silicone airbag.

[0016] Furthermore, the pressure applied to the silicone airbag in a single press is the same as the pressure applied to the full depth of the silicone airbag.

[0017] Furthermore, the electrode material in step (1) is an anode material with a particle size ≥ 100 mesh; the molding pressure in step (1) is 80-90 MPa, and the holding time is 20 s.

[0018] Furthermore, the electrode material in step (1) is nickel oxide.

[0019] Furthermore, the electrolyte powder material in step (2) is yttrium oxide-stabilized zirconium oxide (YSZ), cerium dioxide-based electrolyte, or lanthanum gallate-based electrolyte; the compression molding pressure in step (2) is 90-100 MPa, and the holding time is 30 s.

[0020] Furthermore, in step (2), the particle size of the electrolyte powder material is ≥90 mesh.

[0021] Furthermore, in step (3), the high-temperature calcination temperature is 1300-1500℃, the calcination time is 4-6 h, and the heating rate is 5℃ / min.

[0022] Furthermore, in step (3), the high-temperature calcination temperature is 1400℃ and the calcination time is 5 h.

[0023] Furthermore, in step (4), the cathode paste is lanthanum strontium manganese oxide (La). 0.8 Sr 0.2 MnO3-based, Lanthanum-Strontium-Cobalt Iron Oxide (LSCF)-based La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ Barium Strontium Cobalt Iron Oxide (BSCF)-based Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O3-δ, etc.

[0024] The beneficial effects of this invention are: 1. The process of this invention is simple to operate and can be used to prepare dense and uniform electrolyte films of various thicknesses for electrode-supported batteries in batches.

[0025] 2. Compared to the traditional dry pressing method, which involves spreading a certain amount of powder onto the electrode layer, in order to ensure that the electrolyte layer can isolate the anode and cathode, a certain amount of electrolyte layer powder needs to be evenly spread onto the electrode layer using toothpicks. The spreading process is relatively cumbersome and the electrolyte layer is relatively thick. This invention adopts a dust self-settling preparation process. First, the electrolyte powder is dispersed by controlling the airflow to form dust. Then, the dust settles onto the surface of the electrode layer and is co-pressed to form a double-layer green body of electrode / electrolyte layer. This method has the advantages of simple operation and a thinner electrolyte layer.

[0026] 3. The solid oxide fuel cell electrolyte membrane of this invention, characterized by dust self-settling, is suitable for preparing electrode-supported electrolyte membranes. Compared with the dry pressing method used in traditional electrolytically supported electrolyte membranes, the preparation process only requires four major steps: dry pressing, powder spraying, co-pressing, and calcination. The resulting solid oxide fuel cell electrolyte membrane is thinner, shortens the ion conduction path, and significantly improves battery performance. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the powder spraying bottle structure used in the preparation process of this invention; Figure 2 Image of a thin sheet product obtained by vertical spraying using an existing powder spraying bottle; Figure 3 This invention examines the effect of the number of blasting cycles on the thin sheet product obtained by blasting. Figure 4 This is a SEM image of the anode / electrolyte / cathode three-layer structure thin film of Embodiment 1 of the present invention; Figure 5 SEM images of a three-layer anode / electrolyte / cathode sheet film prepared by the conventional dry pressing method; Figure 6 This is a SEM image of the anode / electrolyte / cathode three-layer structure thin film of Embodiment 2 of the present invention; Figure 7 This is a SEM image of the anode / electrolyte / cathode three-layer structure thin film of Embodiment 3 of the present invention; Figure 8 The IVP curves of the battery prepared by the electrolyte film in Example 1 of the present invention and the electrolyte film-based battery prepared by the conventional dry pressing method are shown in SOFC mode. Figure 9 EIS curves of the battery prepared by the electrolyte film in Example 1 of the present invention and the electrolyte film-based battery prepared by the conventional dry pressing method in SOFC mode; in, Figures 8-9The terms "improved" and "traditional" in the text refer to the battery prepared by the solid oxide fuel cell electrolyte film in Example 1 of this invention and the electrolyte film-based battery prepared by the traditional dry pressing method, respectively.

[0028] In the picture, 1 is the bottle body, 2 is the stainless steel nozzle, 3 is the silicone airbag, 4 is the bend, and 5 is the horn cover. Detailed Implementation

[0029] To clearly illustrate the technical features of this solution, the invention will be described in detail below through specific embodiments and in conjunction with the accompanying drawings. The scope of this invention is not limited to the following embodiments. Those skilled in the art will understand that various changes and modifications can be made to this invention without departing from its spirit and scope.

[0030] Unless otherwise specified, the instruments, reagents, and materials used in the following embodiments are all conventional instruments, reagents, and materials already available in the prior art and can be obtained through legitimate commercial channels. Unless otherwise specified, the experimental methods and detection methods used in the following embodiments are all conventional experimental methods and detection methods already available in the prior art. Example 1

[0031] A dust self-settling preparation process for a solid oxide fuel cell electrolyte film, using NiO as the anode material and BZCYbY(BaZr) 0.1 Ce 0.7 Yb 0.1 Y 0.1 Using O3 as the electrolyte, a BZCYbY electrolyte film was prepared. The specific operation steps are as follows: (1) Grind NiO evenly, weigh 0.4 g of powder, and press it into a thin sheet with a thickness of about 460 μm by pressing it under 80 MPa pressure for 20 s using a tablet press with a diameter of 15 mm. (2) Pass BZCYbY powder through a 100-mesh sieve and put it into a powder spraying bottle to spray out electrolyte dust and uniformly settle on the surface of the thin film obtained in step (1); press it on a tablet press at 90 MPa pressure for 30s to form a double-layer green body consisting of an electrode and an electrolyte layer. (3) The double-layer green body was calcined in a muffle furnace at 1400 °C for 5 h with a heating rate of 5 °C / min to obtain a thin and dense uniform electrode-supported solid oxide fuel cell electrolyte film. (4) Spray a cathode paste layer - barium strontium cobalt ferrite (BSCF) Ba onto the surface of the electrolyte film. 0.5 Sr 0.5 Co 0.8 Fe 0.2 O3-δ-based materials were used to prepare a three-layer structure sheet for anode / electrolyte / cathode.

[0032] In step (2) above, the electrolyte dust settles uniformly by means of... Figure 1 The powder spraying bottle shown has the following structure: It includes a bottle body and a reversing component mounted on the bottle body. The bottle body comprises a bottle body 1 (30-50ml capacity), a stainless steel spray nozzle 2, and a silicone airbag 3. The reversing component is connected at a 90° angle to the front end of the stainless steel spray nozzle 2. The reversing component includes a bent tube 4 connected to the front end of the stainless steel spray nozzle 2, with the bent tube having the same inner diameter as the stainless steel spray nozzle. A horn cover 5 is connected to the bottom end of the bent tube 4, and the inner diameter of the bottom end of the horn cover 5 is approximately equal to the outer diameter of the thin sheet to be sprayed. The length of the bent tube is 1-2cm.

[0033] Control the vertical distance between the bottom of the above-mentioned horn cover and the thin sheet to be sprayed to be 5cm. Press the silicone airbag 10 times continuously so that the sprayed dust enters the horn cover after passing through the bend and falls onto the thin sheet to be sprayed.

[0034] See Figure 2 The result is that the powder is directly sprayed and settled using a general powder spraying bottle or a powder spraying bottle with an unmodified structure (silicone airbag, stainless steel nozzle, bottle body). During the vertical spraying and settling process, on the one hand, the powder is easy to clog, and on the other hand, the film formed on most of the thin films in the figure has small white spots that are visible to the naked eye, and the effect is difficult to meet the product requirements.

[0035] See Figure 3 The product obtained through the above-described steps of spraying and sinking shows that, compared to Figure 2 The product is sprayed evenly with no sedimentation points; among them... Figure 3 The top row of three thin-film products has 13, 13, and 14 spraying times respectively, while the bottom row has 10, 11, and 12 spraying times respectively. Therefore, the preferred number of spraying times is 10-20.

[0036] The single cell prepared in Example 1 above was placed in hydrogen gas and reduced at 700 degrees Celsius for 2 hours. After cooling to room temperature under an inert atmosphere, it underwent gold sputtering. The thickness and density of the electrolyte were tested using SEM. Figure 4 As shown, the thickness of the electrolyte film prepared above was measured to be 8.35 μm. In comparison, the thickness of the electrolyte film prepared by the traditional direct dry pressing method (0.15 g BZCYbY powder) was 20 μm. Figure 5 As shown, both methods produce dense electrolyte films. However, compared to electrolyte films prepared by the traditional dry pressing method, the electrolyte film prepared by the process in this embodiment is significantly thinner. Example 2

[0037] Compared to electrolyte films prepared by the traditional dry pressing method, the electrolyte film prepared by the process in this embodiment is also very thin and dense. By adjusting the number of spraying passes and the distance of the sieved BZCYbY powder, the thickness of the electrolyte film in this embodiment can be controllably adjusted. In this embodiment, the number of powder spraying passes is 12, and the spraying distance is 5 cm. Figure 6 As shown, the thickness of the prepared electrolyte film is 10.9 μm. Example 3

[0038] Compared to electrolyte films prepared by the traditional dry pressing method, the electrolyte film prepared by the process in this embodiment is thinner and denser. By adjusting the number of spraying passes and the distance of the sieved BZCYbY powder, the thickness of the electrolyte film in this embodiment can be controllably adjusted. In this embodiment, the number of powder spraying passes is 14, and the spraying distance is 5 cm. Figure 7 As shown, the thickness of the prepared electrolyte film is 13.4 μm. Example 4

[0039] A cathode paste layer—lanthanum strontium manganese oxide (La)—is sprayed onto the surface of a YSZ electrolyte film prepared by the conventional dry pressing method. 0.8 Sr 0.2 A battery based on MnO3 was prepared and used for comparison with a battery made from a solid oxide fuel cell electrolyte film prepared in Example 1.

[0040] The electrochemical performance of the battery was tested using an electrochemical workstation at 700°C and under H2 atmosphere, respectively. Figure 8 , 9 As shown, the current-voltage (power) curve is obtained. From... Figure 8 It can be seen that the highest power density of electrolyte-based batteries prepared by the traditional dry pressing method is 0.68 W / cm². -2 Maximum current density 0.85 A cm⁻¹ -2 Under the same conditions, the improved battery fabricated from the solid oxide fuel cell electrolyte film prepared by the self-settling of dust in this invention exhibits significantly improved performance, with its maximum power density and maximum current density increasing to 1.35 W / cm². -2 and 1.59A cm -2 .

[0041] like Figure 9 Electrochemical impedance spectroscopy (EIS) curves of the battery were measured using an electrochemical workstation under H2 atmosphere at 850℃. It was found that the ohmic impedance and polarization impedance of the electrolyte-based battery prepared by the conventional dry pressing method were 0.12 and 0.15 Ωcm, respectively. -2Furthermore, compared to electrolyte-based batteries prepared by the traditional dry pressing method, under the same conditions, the improved battery fabricated from the solid oxide fuel cell electrolyte film prepared by the self-settling of dust in this invention exhibits a significantly reduced impedance. Under the same conditions, the ohmic impedance and polarization impedance are reduced to 0.09 and 0.09 Ωcm, respectively. -2 The ohmic impedance of a battery is closely related to the thickness of the electrolyte. Therefore, a thinner electrolyte helps to reduce ohmic impedance, thereby shortening the electrolyte conduction path and improving battery performance.

[0042] The above specific embodiments should not be construed as limiting the scope of protection of the present invention. For those skilled in the art, any alternative improvements or modifications made to the embodiments of the present invention shall fall within the scope of protection of the present invention.

[0043] Any aspects of this invention not described in detail are well-known to those skilled in the art.

Claims

1. A dust self-settling preparation process for a solid oxide fuel cell electrolyte membrane, characterized in that, The process includes dry pressing, powder spraying, co-pressing, and calcination. The specific steps are as follows: (1) Grind the electrode material of the fuel cell evenly, and mold it into a sheet to obtain a thin sheet; (2) The electrolyte powder material used to prepare the electrolyte film is sprayed and settled through a powder spraying bottle, so that the electrolyte powder forms dust and settles uniformly on the surface of the thin film obtained in step (1), and co-pressed to form a double-layer green body of electrode / electrolyte layer; wherein the particle size of the electrolyte powder material is 60-100 mesh. (3) After being placed in a high-temperature muffle furnace for high-temperature calcination, a thin and uniform electrode-supported solid oxide fuel cell electrolyte film is obtained.

2. The dust self-settling preparation process of the solid oxide fuel cell electrolyte film according to claim 1, characterized in that, The control conditions for the formation and uniform self-settling of dust in step (2) are as follows: the airflow velocity for the electrolyte powder material is adjusted to 0.2-0.5 m / s, the vertical distance between the outlet of the electrolyte powder material and the electrode sheet is 3-8 cm, and the number of spraying times is 10-20.

3. The dust self-settling preparation process of the solid oxide fuel cell electrolyte film according to claim 1, characterized in that, In step (2), the powder spraying bottle includes a 30-50mL airbag powder spraying bottle. A bent tube is set at the nozzle outlet end of the airbag powder spraying bottle, and a cover is set at the bottom end of the bent tube. When in use, the vertical distance between the bottom end of the cover and the electrode sheet is 3-8cm, and the number of spraying times is 10-20 times.

4. The dust self-settling preparation process of the solid oxide fuel cell electrolyte film according to claim 3, characterized in that, The airbag powder spray bottle includes a silicone airbag, a stainless steel spray pipe and a bottle body. The bent pipe is located at the outlet end of the stainless steel spray pipe and is a 90° arc transition bent pipe. The cover is a horn cover, and the bottom end of the horn cover is covered with an electrode sheet.

5. The dust self-settling preparation process of the solid oxide fuel cell electrolyte film according to claim 1, characterized in that, The electrode material in step (1) is an anode material with a particle size ≥ 100 mesh; the molding pressure in step (1) is 80-90 MPa and the holding time is 20 s.

6. The dust self-settling preparation process of the solid oxide fuel cell electrolyte film according to claim 5, characterized in that, The electrode material in step (1) is nickel oxide, which is the anode material.

7. The dust self-settling preparation process of the solid oxide fuel cell electrolyte film according to claim 1, characterized in that, The electrolyte powder material in step (2) is yttrium oxide-stabilized zirconium oxide (YSZ), cerium dioxide-based electrolyte, or lanthanum gallate-based electrolyte; the compression molding pressure in step (2) is 90-100 MPa, and the holding time is 30 s.

8. The dust self-settling preparation process of the solid oxide fuel cell electrolyte film according to claim 1, characterized in that, Step (3) The high-temperature calcination temperature is 1300-1500℃, the calcination time is 4-6 h, and the heating rate is 5℃ / min.

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