Method for preparing ultrathin electrolyte film through spin coating

Abstract

The invention provides a method for preparing an ultrathin electrolyte film through spin coating, and belongs to the technical field of fuel cells. The method comprises the following steps: preparing a reaction solution containing YSZ powder, ethyl cellulose and terpilenol, adding polyvinyl butyral to obtain a spin-coating solution, performing ball milling on the spin-coating solution to enable the spin-coating solution to be uniform, performing ultrasonic dispersion work in advance, applying the spin-coating solution to an anode substrate, transferring the anode substrate to a spin coater for spin-coating work, and drying the anode substrate. And drying the electrolyte layer and the substrate, carrying out warm isostatic pressing, and finally carrying out press burning to obtain the ultrathin electrolyte film. The electrolyte is prepared on the structural material substrates of different sizes through the spin-coating method, the production requirements of products of various specifications are met, the production cost is reduced, and the problem that the size and thickness of a traditional deposited electrolyte layer are difficult to control is solved. The ultrathin electrolyte film prepared by the invention has high density, excellent chemical stability and good electrochemical performance.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and particularly to a method for spin-coating to prepare an ultra-thin electrolyte film. Background Art

[0002] Solid Oxide Cells (SOCs) can utilize the electrochemical reaction of clean fuels and oxidants to achieve the direct and efficient conversion between electrical energy and chemical energy. Compared with internal combustion engines, they are more environmentally friendly and efficient energy conversion devices. It includes two working modes: the fuel cell mode (FC) that continuously converts the chemical energy of fuel into electrical energy through an electrochemical reaction; and the electrolysis cell mode (EC) that can use electrical energy to electrolyze water to produce hydrogen and store it in the form of chemical energy. For SOCs, whether it is protonic SOC, ionic SOC or mixed ionic conductor SOC, the conduction of protons and ions requires an electrolyte. For non-electrolyte-supported batteries, the thickness of the electrolyte layer has a more significant impact on the battery performance. Reducing the electrolyte thickness can effectively reduce the ohmic impedance, improve the battery output power and lower the battery operating temperature range. The preparation technologies of SOC electrolyte films mainly include tape casting technology, screen printing technology, electrophoretic deposition technology, slurry 3D printing technology, sol-gel technology, etc. In these preparation technologies, there are the following problems: (1) The commercial technologies for preparing electrolytes cannot ensure that the electrolyte has both a low thickness and a large density, which limits the battery performance; (2) The production cost of the laboratory preparation technologies for electrolytes is relatively high, the process flow is relatively complex, the industrialization foundation is poor, and the size of the produced electrolytes is limited by the scale of the preparation instruments. Therefore, there is an urgent need to provide a new method for preparing the electrolyte of SOC batteries, which can obtain an electrolyte that is uniform, flat and can flexibly control the thickness, and can also achieve the densification and thinning of the electrolyte, and has a simple process and a certain industrialization foundation, and can be effectively applied to large-scale production. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for spin-coating to prepare an ultra-thin electrolyte film, which prepares an electrolyte on the substrate of structural materials with different sizes by spin-coating, meets the production requirements of various specifications of products, reduces the production cost, and solves the problem that it is difficult to control the size and thickness of the traditional deposited electrolyte layer. The prepared ultra-thin electrolyte film has high density, excellent chemical stability and good electrochemical performance.

[0004] To achieve the above purpose, the present invention provides a method for spin-coating to prepare an ultra-thin electrolyte film, including the following steps: Step S1: Prepare a reaction solution containing 60 - 70% by mass of yttria - stabilized zirconia ceramic powder (Yttria - Stabilized Zirconia, abbreviated as YSZ), 3% ethyl cellulose, and 20 - 30% terpineol. Step S2: Add polyvinyl butyral to the reaction solution to obtain a spin - coating solution. Step S3: Ball - mill the obtained spin - coating solution in sequence to make it uniform. Step S4: Perform ultrasonic dispersion work in advance before dropping the spin - coating solution. Step S5: Apply the spin - coating solution onto the anode substrate. Step S6: Transfer the substrate to a spin coater and perform spin - coating work. Step S7: Dry the electrolyte layer and the substrate, and perform warm isostatic pressing. Step S8: Sinter by pressure, and finally obtain an ultra - thin electrolyte film.

[0005] Preferably, in step S1, the particle size of the YSZ powder is 0.1 - 0.5 μm.

[0006] Preferably, in step S2, the polyvinyl butyral accounts for 2% of the total mass of the reaction solution.

[0007] Preferably, in step S3, it specifically includes: using a planetary ball mill to ball - mill the spin - coating solution in step S2 at a rotation speed of 600 r / min.

[0008] Preferably, in step S4, during ultrasonic dispersion, the temperature is 30 °C and it lasts for 10 min.

[0009] Preferably, in step S5, it specifically includes: Step S51: Obtain the anode substrate by cutting. Step S52: Drop the spin - coating solution onto the anode substrate through a pipette.

[0010] Preferably, in step S6, it specifically includes: Step S61: Adsorb the substrate with the spin - coating solution on the spin coater. Step S62: Set the rotation speed of the spin coater to 30 - 60 r / min and the time to 10 - 60 s.

[0011] Preferably, in step S7, it specifically includes: Step S71: Place the deposited anode substrate in a high - temperature furnace. Step S72: Keep the temperature at 80 °C for 30 min. Step S73: Put the dried sample into a warm isostatic press and perform warm isostatic pressing at 80 °C and 20 MPa.

[0012] Preferably, in step S8, it specifically includes: Step S81: Place the billet after warm isostatic pressing between two zirconium plates padded with porcelain chips; Step S82: Place it in a muffle furnace, set the maximum temperature to 1400 °C, and carry out pressure sintering.

[0013] Preferably, in step S8, the thickness of the ultra-thin electrolyte film is less than or equal to 5 μm.

[0014] Therefore, the present invention adopts the above-mentioned method for spin-coating to prepare an ultra-thin electrolyte film, and the beneficial technical effects are as follows: (1) By using the deposition method of spin-coating technology, the present invention can prepare electrolytes on the substrates of structural materials with different sizes, meeting the production of various specifications of products; (2) The deposition method of the present invention does not require expensive instruments used in deposition methods such as laser deposition and spraying method, which can reduce production costs; (3) By adding the prepared spin-coating solution to a substrate with a fixed size for deposition, the present invention can control the thickness of the electrolyte film by adjusting the amount of the spin-coating solution, and at the same time solves the problem that it is difficult to prepare the traditional deposited electrolyte layer with low cost and difficult to control the size and thickness. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a flowchart of the method for spin-coating to prepare an ultra-thin electrolyte film of the present invention; Figure 2 is a surface image of the film electrolyte obtained in Example 1 of the present invention taken by scanning electron microscope (SEM); Figure 3 is a cross-sectional image of the substrate of the deposited film electrolyte obtained in Example 3 of the present invention taken by scanning electron microscope (SEM); Figure 4 is a partially enlarged X-ray diffraction (XRD) diagram of the film electrolyte obtained in Example 2 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] The technical solutions of the present invention will be further described below with reference to the drawings and embodiments.

[0017] Unless otherwise defined, the technical terms or scientific terms used in the present invention shall have the ordinary meanings understood by those of ordinary skill in the field to which the present invention belongs.

[0018] Example 1 Step S1: Prepare a reaction solution containing 70% YSZ powder, 3% ethyl cellulose and 20% pine oil alcohol; wherein, the particle size of the YSZ powder is 0.5 μm; Step S2: Add 2% polyvinyl butyral to the reaction solution to obtain a spin coating solution; Step S3: Place the spin coating solution in a bottle and ball mill it on a planetary ball mill at a rotation speed of 600 r / min for 24 h; Step S4: Ultrasonically disperse the spin coating solution in advance, set the temperature at 30 °C and the time at 10 min; Step S5: Apply the spin coating solution to the anode substrate cut to a fixed size through a pipette; Step S6: Transfer the substrate with the spin coating solution to a spin coater, set the rotation speed at 30 r / min and the rotation time at 30 s; Step S7: Place the coating in a high-temperature furnace and dry it at 80 °C for 30 min. Put the dried sample into a warm isostatic press and perform warm isostatic pressing at 80 °C and 20 MPa for 5 min; Step S8: Place the green body between two zirconium plates padded with 0.9 cm ceramic chips and perform pressure sintering at a maximum temperature of 1400 °C.

[0019] Get as Figure 2 shown an electrolyte film with a thickness of 5 μm.

[0020] Example 2 Step S1: Prepare a reaction solution containing 67.5% YSZ powder, 3% ethyl cellulose and 22.5% terpineol; among them, the particle size of the YSZ powder is 0.5 μm; Step S2: Add 2% polyvinyl butyral to the reaction solution to obtain a spin coating solution; Step S3: Place the spin coating solution in a bottle and ball mill it on a planetary ball mill at a rotation speed of 600 r / min for 24 h; Step S4: Ultrasonically disperse the spin coating solution in advance, set the temperature at 30 °C and the time at 10 min; Step S5: Apply the spin coating solution to the anode substrate cut to a fixed size through a pipette; Step S6: Transfer the substrate with the spin coating solution to a spin coater, set the rotation speed at 35 r / min and the rotation time at 30 s; Step S7: Place the coating in a high-temperature furnace and dry it at 80 °C for 30 min. Put the dried sample into a warm isostatic press and perform warm isostatic pressing at 80 °C and 20 MPa for 5 min; Step S8: Place the green body between two zirconium plates padded with 0.9 cm ceramic chips and perform pressure sintering at a maximum temperature of 1400 °C.

[0021] Get an electrolyte film with a thickness of about 4 μm, as Figure 4As shown, the characteristic peaks of the electrolyte film prepared by the spin coating method are consistent with the standard spectrum, proving that it is YSZ.

[0022] Example 3 Step S1: Prepare a reaction solution containing 65% YSZ powder, 3% ethyl cellulose, and 25% terpineol; among them, the particle size of the YSZ powder is 0.3 μm; Step S2: Add 2% polyvinyl butyral to the reaction solution to obtain a spin coating solution; Step S3: Place the spin coating solution in a bottle and ball mill it on a planetary ball mill at a rotation speed of 600 r / min for 24 h; Step S4: Ultrasonically disperse the spin coating solution in advance, set the temperature at 30 °C, and the time at 10 min; Step S5: Apply the spin coating solution to the anode substrate cut to a fixed size through a pipette; Step S6: Transfer the substrate with the spin coating solution to a spin coater, set the rotation speed at 40 r / min, and the rotation time at 40 s; Step S7: Place the coating in a high-temperature furnace and dry it at 80 °C for 30 min. Put the dried sample into a warm isostatic press and perform warm isostatic pressing at 80 °C and 20 MPa for 5 min; Step S8: Place the green body between two zirconium plates padded with 0.9 cm ceramic chips and perform pressure sintering, with the maximum temperature being 1400 °C.

[0023] Obtain Figure 3 an electrolyte film with a thickness of about 3 μm as shown.

[0024] Example 4 Step S1: Prepare a reaction solution containing 62.5% YSZ powder, 3% ethyl cellulose, and 27.5% terpineol; among them, the particle size of the YSZ powder is 0.1 μm; Step S2: Add 2% polyvinyl butyral to the reaction solution to obtain a spin coating solution; Step S3: Place the spin coating solution in a bottle and ball mill it on a planetary ball mill at a rotation speed of 600 r / min for 24 h; Step S4: Ultrasonically disperse the spin coating solution in advance, set the temperature at 30 °C, and the time at 10 min; Step S5: Apply the spin coating solution to the anode substrate cut to a fixed size through a pipette; Step S6: Transfer the substrate with the spin coating solution to a spin coater, set the rotation speed at 50 r / min, and the rotation time at 45 s; Step S7: Place the coating in a high-temperature furnace and conduct a drying treatment at 80 °C for 30 min. Then, put the dried sample into a warm isostatic press and perform warm isostatic pressing at 80 °C and 20 MPa for 5 min; Step S8: Place the green body between two zirconium plates with 0.9 cm thick ceramic chips and conduct pressure sintering, with the maximum temperature being 1400 °C.

[0025] An electrolyte film with a thickness of about 2 μm is obtained.

[0026] Example Five Step S1: Prepare a reaction solution containing 60% YSZ powder, 3% ethyl cellulose, and 30% terpineol; among them, the particle size of the YSZ powder is 0.1 μm; Step S2: Add 2% polyvinyl butyral to the reaction solution to obtain a spin coating solution; Step S3: Bottle the spin coating solution and place it on a planetary ball mill for ball milling at a rotation speed of 600 r / min for 24 h; Step S4: Pre-ultrasonically disperse the spin coating solution at a set temperature of 30 °C for 10 min; Step S5: Apply the spin coating solution to a cut anode substrate with a fixed size through a pipette; Step S6: Transfer the substrate with the spin coating solution to a spin coater, and set the rotation speed to 60 r / min and the rotation time to 60 s; Step S7: Place the coating in a high-temperature furnace and conduct a drying treatment at 80 °C for 30 min. Then, put the dried sample into a warm isostatic press and perform warm isostatic pressing at 80 °C and 20 MPa for 5 min; Step S8: Place the green body between two zirconium plates with 0.9 cm thick ceramic chips and conduct pressure sintering, with the maximum temperature being 1400 °C.

[0027] An electrolyte film with a thickness of about 1 μm is obtained.

[0028] It can be proved through the above five examples that an ultra-thin electrolyte film with a thickness within 5 μm can be prepared by using the spin coating technique and the spin coating solution in the present invention.

[0029] Next, the performance parameters of the ultra-thin electrolyte film are evaluated through test experiments, including film thickness, electrolyte density, and chemical stability tests.

[0030] Experimental steps: Prepare an ultra-thin electrolyte film and prepare five samples according to the above five examples respectively.

[0031] Measurement of film thickness: Use a scanning electron microscope to photograph the cross-sectional morphology of the sample to measure the film thickness.

[0032] Electrolyte density test: The compactness of the film distribution is characterized by observing the surface morphology of the sample through a scanning electron microscope.

[0033] Chemical stability test: Prepare several YSZ wafers with a thickness of 5 mm by dry pressing method.

[0034] Deposit an appropriate amount of spin coating solution on the YSZ wafers respectively according to the methods of the above five embodiments as the specimens for chemical stability test.

[0035] Measure the initial mass of the sample.

[0036] Prepare a group of concentrated nitric acid solutions with a nitric acid content of 65 - 68%.

[0037] Immerse the specimens in a beaker containing the concentrated nitric acid solution and let it stand for 24 h.

[0038] Take out the samples from the concentrated nitric acid solution, wash them with deionized water and then dry them.

[0039] Measure the mass of the samples again and record the change in mass.

[0040] Record the experimental data: Save the pictures of the cross-section and surface morphology of the samples taken by the scanning electron microscope, and record the results of the chemical stability test.

[0041] Insert the pictures taken by the scanning electron microscope and make a data table to organize and analyze the experimental results.

[0042] Data analysis is shown in Table 1: Table 1 Analysis results ;

[0043] Summarize as follows: Thickness: The sample of Example 1 has the smallest thickness of 1.407 μm, and the thicknesses of the other samples are 2.218 μm (Example 2), 3.182 μm (Example 3), 4.170 μm (Example 4), and 4.760 μm (Example 5) respectively.

[0044] Chemical stability: Test by observing the mass loss of the sample before and after soaking in a concentrated nitric acid solution with a nitric acid content of 65 - 68% for a certain period of time.

[0045] The method for preparing YSZ thin films of the present invention is also applicable to preparing a high-density barrier layer to prevent element diffusion.

[0046] It should be noted that the content not elaborated in detail in the present invention is prior art and well-known to those skilled in the art.

[0047] Therefore, the present invention adopts the above method for spin-coating to prepare an ultra-thin electrolyte film. By using the spin-coating method to prepare electrolytes on the substrates of structural materials with different sizes, it can meet the production requirements of various specifications of products, reduce production costs, and solve the problem that it is difficult to control the size and thickness of the traditional deposited electrolyte layer. The prepared ultra-thin electrolyte film has high density, excellent chemical stability and good electrochemical performance.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions of the present invention or make equivalent replacements, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing an ultra-thin electrolyte film by spin coating, characterized in that: The following steps are involved: Step S1, preparing a reaction solution containing 60-70% YSZ powder, 3% ethyl cellulose and 20-30% terpineol by weight; Step S2, adding polyvinyl butyral to the reaction solution to obtain a spin coating solution; Step S3, ball-milling the obtained spin-coating liquid in sequence to make it uniform; Step S4, performing ultrasonic dispersion before adding the spin coating liquid; Step S5, applying the spin coating liquid onto the anode substrate; Step S6, transferring the substrate to a coating machine for spin coating; Step S7, drying the electrolyte layer and the substrate, and performing warm isostatic pressing; Step S8: pressure sintering to finally obtain an ultra-thin electrolyte film.

2. The method for preparing an ultra-thin electrolyte film by spin coating according to claim 1, characterized in that: In step S1, the particle size of the YSZ powder is 0.1-0.5 μm.

3. The method for preparing an ultra-thin electrolyte film by spin coating according to claim 1, characterized in that: In step S2, polyvinyl butyral accounts for 2% of the total mass of the reaction solution.

4. The method for preparing an ultra-thin electrolyte film by spin coating according to claim 1, characterized in that: Step S3 specifically includes: using a planetary ball mill to ball mill the spin coating liquid in step S2 at a rotation speed of 600 r / min.

5. The method for preparing an ultra-thin electrolyte film by spin coating according to claim 1, characterized in that: In step S4, the ultrasonic dispersion is carried out at a temperature of 30° C. for 10 min.

6. The method for preparing an ultra-thin electrolyte film by spin coating according to claim 1, characterized in that: Step S5 specifically includes: Step S51, obtaining an anode substrate by cutting; Step S52: drop the spin coating liquid onto the anode substrate by using a pipette gun.

7. The method for preparing an ultra-thin electrolyte film by spin coating according to claim 6, characterized in that: Step S6 specifically includes: Step S61, adsorbing the substrate with the spin coating liquid on a coating machine; Step S62, the speed of the glue spreader is set to 30-60 r / min and the time is 10-60 s.

8. The method for preparing an ultra-thin electrolyte film by spin coating according to claim 1, characterized in that: Step S7 specifically includes: Step S71, placing the deposited anode substrate in a high temperature furnace; Step S72, maintaining the temperature at 80°C for 30 minutes; Step S73: Place the dried sample into a warm isostatic press and perform warm isostatic pressing at 80° C. and 20 MPa.

9. The method for preparing an ultra-thin electrolyte film by spin coating according to claim 1, characterized in that: Step S8 specifically includes: Step S81, placing the green body after warm isostatic pressing between two zirconium plates padded with ceramic sheets; Step S82, placing in a muffle furnace, setting the maximum temperature to 1400°C, and performing pressure sintering.

10. The method for preparing an ultra-thin electrolyte film by spin coating according to claim 1, characterized in that: In step S8, the thickness of the ultra-thin electrolyte film is less than or equal to 5 μm.

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