A method for preparing an ultrathin electrolyte film by natural deposition

Abstract

The application provides a method for preparing an ultrathin electrolyte film by natural deposition, 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 terpineol, adding polyvinylpyrrolidone to obtain a coating liquid, ball milling the coating liquid to obtain a uniform deposition liquid, preparing a novel substrate with a fixed-size frame based on an anode substrate, performing ultrasonic dispersion in advance, applying the deposition liquid to the prepared novel substrate, allowing the coating layer to naturally volatilize and deposit under specific conditions, drying the electrolyte layer and the substrate and performing warm isostatic pressing, and finally performing pressure sintering to obtain a blank with a deposited ultrathin electrolyte layer. The method has the advantages of simple process, low cost and large-scale production, and the prepared ultrathin electrolyte film has high density, excellent chemical stability and good electrochemical performance, and is suitable for the field of fuel cells.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fuel cell technology, in particular to a method for preparing an ultra-thin electrolyte film by natural deposition. BACKGROUND

[0002] Solid oxide cells (SOC) are one of the most clean and efficient energy conversion devices in the 21st century, which can realize the efficient conversion between hydrogen energy and electrical energy, and has two working modes. In fuel cell mode, it is a device that continuously converts the chemical energy of fuel into electrical energy through electrochemical reaction; in electrolysis cell mode, it can convert solar energy, wind energy and other new energy into electrical energy for storage and electrolysis. At present, most of the commercial products of SOC are the third generation products of electrolyte support type, fuel electrode support type and metal support type. For electrolyte support type SOC, the thickness of electrolyte is often ≥200 μm, the thermal conductivity of ceramic electrolyte material is low, the start-up time of the cell is slow, and high working performance can be achieved only at high temperature, and the cost of sealing body, connecting body and heat insulation material is also high. For fuel electrode support type SOC, the thickness of fuel electrode is ≧400 μm, compared with electrolyte type SOC, it has thinner electrolyte thickness and lower working temperature, but the overall mechanical strength of the cell is low, the sealing difficulty is high, and the cost of electrode material is high. For metal support type SOC, the thickness of electrolyte is about 10-50 μm, and its excellent heat conduction performance makes it have high start-up rate, but due to the existence of metal support, it is difficult to prepare, and the support is easy to be oxidized and the element diffusion between anode is easy to occur. For SOC, whether it is proton type SOC, ion type SOC or mixed ion conductor SOC, the conduction of proton and ion needs to pass through the electrolyte, and the thicker the electrolyte, the longer the conduction path of proton and ion, and the ohmic impedance increases with the increase of electrolyte thickness, that is, the thinner the electrolyte layer, the higher the power generation efficiency. The preparation methods of SOC electrolyte mainly include low temperature sintering method, tape casting method, screen printing method, thermal spraying method, vacuum plasma spraying method and chemical vapor deposition method, etc. In these preparation methods, the following problems exist:

[0003] (1) The commercial preparation method of electrolyte cannot prepare an electrolyte layer with a thickness thin enough;

[0004] (2) The size of electrolyte and barrier layer produced by laboratory preparation method is limited by the specifications of instruments, and the production cost is high and cannot be mass produced.

[0005] Therefore, it is urgent to provide a new method for preparing SOC cell electrolyte, which can realize electrolyte thinning and stable control of the thickness of the deposited electrolyte and can be applied to mass production. SUMMARY

[0006] The application aims to provide a method for preparing an ultra-thin electrolyte film through natural deposition, which has the advantages of simple process, low cost and large-scale production, and the prepared ultra-thin electrolyte film has high density, excellent chemical stability and good electrochemical performance, and is suitable for the field of fuel cells.

[0007] To achieve the above-mentioned purpose, the application provides a method for preparing an ultra-thin electrolyte film through natural deposition, which comprises the following steps:

[0008] Step S1, a reaction solution with mass percentages of 55-65% Yttria-Stabilized Zirconia (YSZ) ceramic powder, 2% ethyl cellulose and 25-35% terpineol is prepared;

[0009] Step S2, polyvinylpyrrolidone is added to the reaction solution to obtain a coating solution;

[0010] Step S3, the obtained coating solution is sequentially subjected to ball milling to obtain a uniform deposition solution;

[0011] Step S4, a novel substrate with a fixed-size frame is prepared based on an anode substrate;

[0012] Step S5, ultrasonic dispersion work is performed in advance before the deposition solution is added dropwise;

[0013] Step S6, the deposition solution is applied to the prepared novel substrate;

[0014] Step S7, the coating layer is subjected to natural volatilization deposition;

[0015] Step S8, the electrolyte layer and the substrate are dried, and warm isostatic pressing is performed;

[0016] Step S9, pressure sintering is performed, and finally, a blank body with a deposited ultra-thin electrolyte layer is obtained.

[0017] Preferably, in step S1, the particle size of the YSZ powder is 0.1-0.5 μm.

[0018] Preferably, in step S2, the polyvinylpyrrolidone accounts for 5% of the total mass of the reaction solution.

[0019] Preferably, in step S3, the specific steps include: using a horizontal ball mill to perform ball milling treatment on the coating solution in step S2, and the rotating speed is 800 r / min.

[0020] Preferably, in step S4, the specific steps include:

[0021] Step S41, a frame is prepared, and the frame is made of plastic;

[0022] Step S42, the frame and the anode substrate are bonded together through organic silicone.

[0023] Step S43, the silicone glue substrate is volatilized dry;

[0024] Step S44, a fixed-size substrate capable of carrying the deposition liquid is obtained.

[0025] Preferably, in step S5, the temperature during ultrasonic dispersion is 30 DEG C, and the duration is 15 min.

[0026] Preferably, in step S7, the method specifically comprises:

[0027] Step S71, the substrate after the deposition liquid is applied is placed in an environment with a constant temperature of 26 DEG C and a constant humidity of 60%.

[0028] Step S72, the substrate is placed on a hollow frame;

[0029] Step S73, volatilization is accelerated by a fan in a fume hood.

[0030] Preferably, in step S8, the method specifically comprises:

[0031] Step S81, the frame is separated from the substrate body by cutting to obtain a fixed-size substrate;

[0032] Step S82, the deposited substrate is placed in a high-temperature furnace;

[0033] Step S83, the temperature is maintained at 80 DEG C, and the holding time is 15 min;

[0034] Step S84, the dried sample is placed in a warm isostatic press for warm isostatic pressing at 80 DEG C and 20 MPa.

[0035] Preferably, in step S9, the method specifically comprises:

[0036] Step S91, the green body after warm isostatic pressing is placed between two zirconium plates padded with porcelain sheets;

[0037] Step S92, the green body is placed in a muffle furnace, the maximum temperature is set to 1400 DEG C, and pressure sintering is performed.

[0038] Preferably, in step S9, the thickness of the ultra-thin electrolyte film is less than or equal to 5 microns.

[0039] Therefore, the method for preparing an ultra-thin electrolyte film by natural deposition has the following beneficial technical effects:

[0040] (1) The method for preparing an ultra-thin electrolyte film by natural deposition can be used to prepare electrolytes on any size of structural material as a substrate, and meet the production of various specifications of products.

[0041] (2) The deposition method of the present application does not need expensive instruments used in laser deposition and spraying method, and can reduce production cost;

[0042] (3) The present application can control the thickness of the electrolyte film by adjusting the amount of the coating liquid, and solve the problems of low-cost preparation of traditional deposition electrolyte layer and difficult control of size and thickness. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 Flow chart of the method for preparing ultra-thin electrolyte film by natural deposition of the present application;

[0044] Figure 2 Surface image of the electrolyte film obtained in Example 1 of the present application, taken by scanning electron microscope (SEM);

[0045] Figure 3 Cross-sectional image of the substrate of the deposited film electrolyte obtained in Example 3 of the present application, taken by scanning electron microscope (SEM);

[0046] Figure 4 X-ray diffraction (XRD) partial enlarged view of the electrolyte film obtained in Example 2 of the present application. DETAILED DESCRIPTION

[0047] The technical solutions of the present application are further described below by means of drawings and examples.

[0048] Unless otherwise defined, the technical terms or scientific terms used in the present application shall have the usual meanings understood by those skilled in the art to which the present application belongs.

[0049] Example 1

[0050] Step S1: preparing a reaction solution containing 55% YSZ, 2% ethyl cellulose and 35% terpineol;

[0051] Step S2: adding 5% polyvinylpyrrolidone to the reaction solution to obtain a coating liquid;

[0052] Step S3: filling the coating liquid into a bottle and placing it on a horizontal ball mill for ball milling at a speed of 800 r / min for 24 h to obtain a deposition liquid;

[0053] Step S4: connecting a square polyvinyl chloride (PVC) frame with a side length of 3 cm and a blank body with silicone glue;

[0054] Step S5: pre-ultrasonic dispersion of the deposition liquid, setting the temperature to 30℃ and the time to 15 min;

[0055] Step S6: The deposition liquid being ultrasonically dispersed is slowly added dropwise and applied on the body with the frame by using a pipette to measure a fixed amount;

[0056] Step S7: The body coated with the electrolyte solution is placed in a fume hood, and the body is suspended to prevent deformation caused by the volatilization of the deposition liquid (to improve the electrolyte deposition effect);

[0057] Step S8: The coating is placed in a high-temperature furnace for drying treatment at 80°C for 15 min, and the dried sample is placed in a warm isostatic pressing machine for warm isostatic pressing operation at 80°C and 20 MPa for 5 min;

[0058] Step S9: The body is placed between two zirconium plates padded with 0.9 cm porcelain tiles for pressure sintering, with a maximum temperature of 1400°C.

[0059] A dense electrolyte thin film with a thickness of 5 μm is obtained as shown in Figure 2 .

[0060] Example Two

[0061] Step S1: A reaction solution containing 57.5% YSZ, 2% ethyl cellulose, and 32.5% terpineol is prepared;

[0062] Step S2: 5% polyvinylpyrrolidone is added to the reaction solution to obtain a coating solution;

[0063] Step S3: The coating solution is bottled and placed on a horizontal ball mill for ball milling at a speed of 800 r / min for 24 h to obtain a deposition liquid;

[0064] Step S4: A square PVC frame with a side length of 3 cm is connected to the body with silicone glue;

[0065] Step S5: The deposition liquid is pre-ultrasonically dispersed at a temperature of 30°C for 15 min;

[0066] Step S6: The deposition liquid being ultrasonically dispersed is slowly added dropwise and applied on the body with the frame by using a pipette to measure a fixed amount;

[0067] Step S7: The body coated with the electrolyte solution is placed in a fume hood, and the body is suspended to prevent deformation caused by the volatilization of the deposition liquid (to improve the electrolyte deposition effect);

[0068] Step S8: The coating is placed in a high-temperature furnace for drying treatment at 80°C for 15 min, and the dried sample is placed in a warm isostatic pressing machine for warm isostatic pressing operation at 80°C and 20 MPa for 5 min;

[0069] Step S9: The blank is placed between two zirconium plates with 0.9 cm of porcelain tile for pressure sintering, with a maximum temperature of 1400℃.

[0070] The electrolyte thin film with a thickness of about 4 μm is obtained; as shown in Figure 4 Figure 1, the thin film electrolyte prepared by natural evaporation deposition is consistent with the characteristic peaks of the standard spectrum, proving that it is YSZ.

[0071] Example Three

[0072] Step S1: A reaction solution containing 60% YSZ, 2% ethyl cellulose and 30% terpineol is prepared;

[0073] Step S2: 5% polyvinylpyrrolidone is added to the reaction solution to obtain a coating solution;

[0074] Step S3: The coating solution is bottled and placed on a horizontal ball mill for ball milling at a speed of 800 r / min for 24 h to obtain a deposition solution;

[0075] Step S4: A square PVC frame with a side length of 3 cm is connected to the blank with silicone glue;

[0076] Step S5: The deposition solution is pre-ultrasonically dispersed, with a temperature of 30℃ and a time of 15 min;

[0077] Step S6: The deposition solution being ultrasonically dispersed is slowly dropped and spread on the blank with the frame by using a pipette;

[0078] Step S7: The blank coated with the electrolyte solution is placed in a fume hood, and the blank is suspended to prevent deformation caused by the evaporation of the deposition solution (to improve the electrolyte deposition effect);

[0079] Step S8: The coating is placed in a high-temperature furnace for drying treatment at 80℃ for 15 min, and the dried sample is placed in a warm isostatic pressing machine for warm isostatic pressing operation at 80℃ and 20 MPa for 5 min;

[0080] Step S9: The blank is placed between two zirconium plates with 0.9 cm of porcelain tile for pressure sintering, with a maximum temperature of 1400℃.

[0081] The electrolyte thin film with a thickness of about 3 μm is obtained as shown in Figure 3 Figure 2.

[0082] Example Four

[0083] Step S1: A reaction solution containing 62.5% YSZ, 2% ethyl cellulose and 27.5% terpineol is prepared;

[0084] Step S2: 5% polyvinylpyrrolidone was added to the reaction solution to obtain a coating liquid;

[0085] Step S3: The coating liquid was placed in a horizontal ball mill for ball milling at a speed of 800 r / min for 24 h to obtain a deposition liquid;

[0086] Step S4: A square PVC frame with a side length of 4 cm was connected to the blank with silicone glue;

[0087] Step S5: The deposition liquid was pre-ultrasonically dispersed at a temperature of 30°C for 15 min;

[0088] Step S6: The deposition liquid being ultrasonically dispersed was slowly added and applied on the blank with the frame using a pipette;

[0089] Step S7: The blank coated with the electrolyte solution was placed in a fume hood, and the blank was suspended to prevent deformation caused by volatilization of the deposition liquid (improve electrolyte deposition effect);

[0090] Step S8: The coating was placed in a high-temperature furnace for drying treatment at 80°C for 15 min, and the dried sample was placed in a warm isostatic pressing machine for warm isostatic pressing operation at 80°C and 20 MPa for 5 min;

[0091] Step S9: The blank was placed between two zirconium plates padded with 0.9 cm porcelain tiles for pressure sintering, and the maximum temperature was 1400°C.

[0092] An electrolyte thin film with a thickness of about 2 μm was obtained.

[0093] Example Five

[0094] Step S1: A reaction solution containing 65% YSZ, 2% ethyl cellulose and 25% terpineol was prepared;

[0095] Step S2: 5% polyvinylpyrrolidone was added to the reaction solution to obtain a coating liquid;

[0096] Step S3: The coating liquid was placed in a horizontal ball mill for ball milling at a speed of 800 r / min for 24 h to obtain a deposition liquid;

[0097] Step S4: A square PVC frame with a side length of 5 cm was connected to the blank with silicone glue;

[0098] Step S5: The deposition liquid was pre-ultrasonically dispersed at a temperature of 30°C for 15 min;

[0099] Step S6: The deposition liquid being ultrasonically dispersed was slowly added and applied on the blank with the frame using a pipette;

[0100] Step S7: Place the body coated with electrolyte solution in a fume hood, and suspend the body to prevent deformation caused by the evaporation of the deposition solution (improve the electrolyte deposition effect);

[0101] Step S8: Place the coating in a high-temperature furnace, dry at 80°C for 15 min, and then place the dried sample in a warm isostatic press at 80°C and 20 MPa for 5 min.

[0102] Step S9: Place the body between two zirconium plates padded with 0.9 cm porcelain tiles for pressure sintering, with a maximum temperature of 1400°C.

[0103] A thickness of about 1 μm of the electrolyte thin film is obtained.

[0104] The above five examples prove that the natural evaporation deposition technique and the deposition solution used in the present application can prepare ultra-thin electrolyte thin films with a thickness of less than 5 μm.

[0105] The performance parameters of the ultra-thin electrolyte thin film are evaluated by test experiments, including film thickness, electrolyte density and chemical stability test.

[0106] Experimental steps:

[0107] Prepare the ultra-thin electrolyte thin film, and prepare five samples according to the above five examples.

[0108] Film thickness test: Use a scanning electron microscope to measure the thickness of the deposited film.

[0109] Electrolyte density test: Observe the surface morphology of the sample by scanning electron microscope to characterize the density of the film distribution.

[0110] Chemical stability test:

[0111] Prepare several YSZ round sheets with a thickness of 5 mm by dry pressing method.

[0112] According to the methods of the above five examples, deposit an appropriate amount of deposition solution on the YSZ round sheet as a test sample for chemical stability test.

[0113] Measure the initial mass of the sample.

[0114] Prepare a group of concentrated nitric acid solution with a nitric acid content of 65-68%.

[0115] Soak the test sample in a beaker containing the concentrated nitric acid solution and stand for 24 h.

[0116] Take the sample out of the concentrated nitric acid solution, wash with deionized water and dry.

[0117] The sample mass is measured again, and the change in mass is recorded.

[0118] The experimental data is recorded:

[0119] The pictures of the cross-section and surface morphology of the sample taken by the scanning electron microscope are saved, and the chemical stability test results are recorded.

[0120] The pictures taken by the scanning electron microscope are inserted, and a data table is made to organize and analyze the experimental results.

[0121] The data analysis is shown in Table 1:

[0122] Table 1 Analysis Results

[0123] ;

[0124] The summary is as follows:

[0125] Thickness: The minimum thickness of the sample of Example 1 is 1.45 μm, and the thicknesses of the other samples are 2.01 μm (Example 2), 3.13 μm (Example 3), 4.27 μm (Example 4), and 4.89 μm (Example 5), respectively.

[0126] Chemical stability: The test is performed by immersing the sample in a concentrated nitric acid solution with a nitric acid content of 65-68% for a certain period of time, and then observing the mass loss of the sample before and after immersion.

[0127] The method for preparing the YSZ thin film of the present application is also applicable to the preparation of a high-density barrier layer for preventing element diffusion.

[0128] It is worth noting that the contents not elaborated in the present application are all prior art and are well known to those skilled in the art.

[0129] Therefore, the method for preparing an ultrathin electrolyte thin film by natural deposition has the advantages of simple process, low cost, and large-scale production, and the prepared ultrathin electrolyte thin film has high density, excellent chemical stability, and good electrochemical performance, and is suitable for use in the field of fuel cells.

[0130] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application and not to limit them, and although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can still be modified or replaced by equivalents, and these modifications or replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. A method for preparing an ultra-thin electrolyte film by natural deposition, characterized in that, The method comprises the following steps: S1, preparing a reaction solution with mass percentage of 55-65% YSZ powder, 2% ethyl cellulose and 25-35% terpineol; S2, adding polyvinylpyrrolidone to the reaction solution to obtain a coating solution, the polyvinylpyrrolidone accounting for 5% of the total mass of the reaction solution; S3, ball milling the obtained coating solution to obtain a uniform deposition solution; S4, preparing a novel substrate with a fixed-size frame based on an anode substrate; S5, performing ultrasonic dispersion before adding the deposition solution; S6, applying the deposition solution to the prepared novel substrate; S7, naturally volatilizing and depositing the coating layer, specifically comprising: S71, placing the substrate after applying the deposition solution in an environment with constant temperature of 26℃ and constant humidity of 60%; S72, placing the substrate on a hollow frame; S73, accelerating volatilization under the action of a fan in a fume hood; S8, drying the electrolyte layer and the substrate and performing warm isostatic pressing; S81, separating the frame from the substrate main body by cutting to obtain a substrate with a fixed size; S82, placing the deposited substrate in a high-temperature furnace; S83, maintaining the temperature at 80℃ for 15 min; S84, placing the dried sample in a warm isostatic pressing machine and performing warm isostatic pressing at 80℃ and 20MPa; S9, pressure sintering, and finally obtaining a green body with a deposited ultra-thin electrolyte layer, and the thickness of the ultra-thin electrolyte film is less than or equal to 5μm.

2. The method of claim 1, wherein the method is characterized by, In S1, the particle size of the YSZ powder is 0.1-0.5μm.

3. The method of claim 1, wherein the method is characterized by, In S3, specifically comprising: using a horizontal ball mill to ball mill the coating solution in S2, and the rotating speed is 800r / min.

4. The method of claim 1, wherein the method is characterized by, In S4, specifically comprising: S41, preparing a frame, and the frame is made of plastic; S42, bonding the frame and the anode substrate together by using organic silicone glue; S43, waiting for the organic silicone glue to volatilize and dry; S44, obtaining a fixed-size substrate capable of bearing the deposition solution.

5. The method of claim 1, wherein the method is characterized by, In S5, during ultrasonic dispersion, the temperature is 30℃ and the duration is 15 min.

6. The method of claim 1, wherein the method is a natural deposition method for preparing an ultra-thin electrolyte film. In S9, specifically comprising: S91, placing the green body after warm isostatic pressing between two zirconium plates with porcelain chips; S92, placing in a muffle furnace, setting the maximum temperature to 1400℃, and performing pressure sintering.

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