Method for determining the flatness of a catalyst coating film and method for obtaining a catalyst coating film

Abstract

This invention provides a method for determining the flatness of a catalyst coating film (CCM) and a method for obtaining a catalyst coating film. [Solution] The catalyst coating film has a test material, and the method includes the steps of: performing a friction force test on the test material to obtain the coefficient of friction of the test material; comparing the coefficient of friction with a predetermined range of 0.1 to 15; and determining the flatness of the catalyst coating film containing the test material by comparing the coefficient of friction with the predetermined range.

Description

Technical Field

[0001] The present invention relates to a method for determining the flatness of a catalyst-coated membrane (CCM) and a method for obtaining a catalyst-coated membrane, and particularly to a method for obtaining a flat CCM based on the friction coefficient of a material.

Background Art

[0002] A fuel cell is an energy conversion device that can directly convert the chemical energy stored in hydrogen fuel and an oxidant into electrical energy through an electrochemical reaction. A fuel cell has the characteristics of high energy conversion efficiency and no emission of waste gas, and is particularly expected to be applied in the transportation field (automobiles, ships, backup power sources, etc.), and is considered to be one of the most promising solutions to solve the energy crisis and environmental pollution. Because of such excellent characteristics, the development and application of fuel cell technology have attracted great attention from governments and enterprises around the world.

[0003] The CCM of a fuel cell is one of the important components of a fuel cell, and its main preparation method is to coat a catalyst slurry on a polymer membrane and dry it to form a CCM. When coating the catalyst slurry on both sides of the polymer membrane, most of the solvents used for the catalyst are alcohols such as methanol, ethanol, propanol, isopropyl alcohol, n-propanol or glycerol, but most of the polymer membranes are perfluorosulfonic acid membranes. Therefore, when coating the catalyst on the polymer membrane, the presence of the alcohol solvent causes the polymer membrane to swell, which affects the quality of the polymer membrane.

[0004] Among the existing CCM manufacturing methods, how to ensure the surface uniformity and flatness of the CCM has always been one of the important research and development technologies in this field. There are many manufacturing methods for CCM (transfer printing method, roll-to-roll (R2R) coating method, brushing method, ultrasonic spraying method and vacuum adsorption method), but these methods need to be carried out under various process constraints, and each has its own drawbacks, and this problem has not been completely solved yet.

[0005] To solve the problems of swelling and deformation of CCM, it is desirable to obtain a flat CCM under minimal process constraints and effectively improve the quality of the CCM. [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The present invention provides a method for determining the flatness of a CCM and a method for obtaining a CCM, which uses the coefficient of friction of a test material as a criterion for determining the flatness of the CCM and obtains a flat CCM by applying a material with a high coefficient of friction. [Means for solving the problem]

[0007] According to one aspect of the present invention, a method for determining the flatness of a catalyst coating film (CCM) is disclosed. The catalyst coating film comprises a test material, and the method includes the steps of: performing a friction force test on the test material to obtain the coefficient of friction of the test material; comparing the coefficient of friction with a predetermined range of 0.1 to 15; and determining the flatness of the catalyst coating film containing the test material by comparing the coefficient of friction with the predetermined range.

[0008] According to one aspect of the present invention, a method for obtaining a catalyst coating film is disclosed. The method includes the steps of: performing a friction force test on a test material to obtain a coefficient of friction of the test material; and, if the coefficient of friction is between 0.1 and 15, using the test material in a catalyst coating film manufacturing process to obtain a catalyst coating film.

[0009] The present invention further discloses a method for obtaining a catalyst coating film. The method includes the steps of: obtaining the coefficient of friction of a test material; determining whether the coefficient of friction is in the range of 0.1 to 15; and, if the coefficient of friction is in the range of 0.1 to 15, using the test material in a catalyst coating film manufacturing process to obtain a catalyst coating film.

[0010] The above embodiments and advantages of the present invention will become more readily apparent to those skilled in the art after reviewing the following detailed description and accompanying drawings. [Brief explanation of the drawing]

[0011] [Figure 1] This is a cross-sectional view of a conventional CCM. [Figure 2] This is a flowchart of a method for determining the flatness of a CCM according to an embodiment of the present invention. [Figure 3] This shows the relationship between the coefficient of friction of various materials according to the embodiment of the present invention and the flatness of the double-sided CCM. [Figure 4] This is a flowchart of a process test according to an embodiment of the present invention. [Figure 5] This is a flowchart of a method for obtaining a CCM according to an embodiment of the present invention. [Modes for carrying out the invention]

[0012] When reading the following detailed description, refer to all the figures of the present invention. All the figures of the present invention illustrate different embodiments of the invention by example and help those skilled in the art to understand how to carry out the invention. These embodiments provide sufficient embodiments to demonstrate the spirit of the invention, each embodiment is non-contradictory to the others, and new embodiments can be carried out through any combination thereof. That is, the present invention is not limited to the embodiments disclosed herein.

[0013] Fuel cells typically contain a polymer membrane sandwiched between an anode catalyst layer and a cathode catalyst layer to form a membrane electrode assembly (MEA). The catalyst layer is coated onto the polymer membrane, and this structure is called a Coated Catalyst Film (CCM). As used herein, the term "polymer membrane" includes cation membranes (proton exchange membranes, PEMs), anion exchange membranes (AEMs), and perfluorosulfonate ion exchange membranes. In this invention, the polymer membrane can be selected as required by practical needs for permeability of different ions.

[0014] Figure 1 shows a cross-sectional view of a conventional CCM10. The CCM10 is a double-sided CCM including a polymer film 12, an anode catalyst layer 14 coated on the upper surface of the polymer film 12, and a cathode catalyst layer 16 coated on the lower surface of the polymer film 12. The CCM10 further includes a gas diffusion layer 17 located on the anode side and a gas diffusion layer 18 located on the cathode side, and has functions such as supporting the catalyst layer, collecting current, conducting gas, and discharging reaction product water.

[0015] In one embodiment of the present invention, a method for determining the flatness of a CCM is provided. According to the method for determining the flatness of a CCM of the present invention, assuming that a test material is used in the CCM, the flatness of the CCM containing the test material can be determined by the coefficient of friction of the test material. The test material can be placed at any suitable position in the CCM and can preferably be combined with at least one catalyst layer in the CCM. For example, the test material can be combined with the anode catalyst layer 14, the cathode catalyst layer 16, or both in Figure 1.

[0016] Figure 2 is a flowchart of a method 100 for determining the flatness of a CCM according to an embodiment of the present invention. In step 110, a friction force test is performed on the test material to obtain the friction coefficient of the test material. In step 120, the friction coefficient is compared with a predetermined range of 0.1 to 15. In step 130, the flatness of the catalyst coating film including the test material is determined by comparing the friction coefficient with the predetermined range. The friction force test used in the present invention includes various methods capable of obtaining the friction coefficient of the test material, such as a method for obtaining the static friction coefficient and the dynamic friction coefficient between two sheets of the same test material. In a preferred embodiment of the present invention, the friction force test is ASTM D1894 and the friction coefficient is the static friction coefficient. However, it should be understood that the friction force test used in the present invention is not limited to the method of the preferred embodiment. Furthermore, those skilled in the art can understand that when performing the friction force test on different test materials, the same test method needs to be used so that the friction coefficients of different test materials serve as a consistent standard.

[0017] In step 120 of FIG. 2, different predetermined ranges can be set according to actual needs. For example, the predetermined range can be a friction coefficient within the range of 0.1 to 15 or any range therebetween, preferably within the range of 1 to 15, more preferably within the range of 5 to 15. In order to establish the relationship between the friction coefficient of the test material and the flatness of the CCM, the present invention conducted experiments as shown in Table 1 for different test materials. The experiments in Table 1 are based on the ASTM D1894 friction force test for obtaining the friction coefficients of various test materials. Double-sided CCMs were manufactured using various test materials, and the flatness of the surface of each manufactured CCM was observed. In this experiment, the test material was formed on a substrate for laminating with one of the catalyst layers in the double-sided CCM under a pressure of 1.288 kgf / cm 2 of the catalyst layer in the double-sided CCM under a pressure of 1.288 kgf / cm.

[0018] [Table 1]

[0019] As shown in Table 1, materials 1 to 5 each have different coefficients of friction. Experimental results have shown that when materials 1 to 5 are used as substrate materials and laminated onto a catalyst layer in a double-sided CCM, the coefficient of friction increases. The higher the coefficient of friction, the flatter the double-sided CCM becomes. As shown in Figure 3, the surfaces of double-sided CCMs made from materials 1 and 2 still have swelling and bulging defects. Double-sided CCMs made from materials 3 to 5 have flat surfaces with no swelling, bulging, or creases. The above experimental results can be used as the basis for determining a predetermined range in step 120 of Figure 2 of the present invention, and can also be used as the basis for determining the flatness of the CCM in step 130. For example, the predetermined range in step 120 can be set to a coefficient of friction of 1 to 15 based on known experimental results. In step 130, if the coefficient of friction of the test material is within the predetermined range, the CCM containing the test material is determined to have a flat surface.

[0020] The method for measuring the flatness of a CCM according to the present invention allows for the selection of a material suitable for the manufacture of a double-sided CCM. In the case of an unknown material under test, if the coefficient of friction of the test material meets a predetermined range, further process tests can be performed on the test material to determine the surface properties of the CCM containing the test material. Figure 4 is a flowchart of a process test according to an embodiment of the present invention. While the process test in Figure 4 is a method for manufacturing a double-sided CCM, it should be understood that the material selected through the method for determining the flatness of a CCM according to the present invention can also be used to manufacture CCMs with other structures. In other words, the process test in Figure 4 is merely an example, and those skilled in the art can adjust the steps of the process test according to their actual needs.

[0021] Referring to FIG. 4, first, in step 210, a polymer membrane is provided, and a first catalyst layer is coated on the first surface of the polymer membrane. Preferably, the polymer membrane is a perfluorosulfonic acid membrane, and the first catalyst layer is, for example, a mixture containing carbon powder, a noble metal and a metal oxide, a perfluorosulfonic acid resin, an alcohol solvent and water. As a method for coating the first catalyst layer on the first surface, various methods commonly used in the art, such as transfer printing, direct coating, brushing, ultrasonic spraying, vacuum adsorption, etc., can be used. In step 220, the test material selected by the method of FIG. 2 is placed on the first catalyst layer, and the test material at least partially overlaps the first catalyst layer. For example, the test material may be arranged on the first catalyst layer in a layer structure, or may cover a part of the first catalyst layer.

[0022] In step 23, pressure is applied to the first catalyst layer provided with the test material to bond the test material to the first catalyst layer. The method of applying pressure to the first catalyst layer in the present invention can be carried out under various environments such as normal temperature pressing, hot pressing, vacuum pressing, etc. In a preferred embodiment of the present invention, the method of applying pressure to the first catalyst layer is normal temperature pressing or vacuum pressing. In step 230, the pressure applied to the first catalyst layer is 0 to 380 kgf / cm 2 , preferably 0 to 50 kgf / cm 2 , more preferably 0 to 10 kgf / cm 2 . For example, in the normal temperature lamination process, the pressure applied to the first catalyst layer is 1.288 kgf / cm 2 .

[0023] In step 240, the second catalyst layer is coated onto the second surface of the polymer film to obtain a double-sided CCM. Depending on the actual requirements of the double-sided CCM, the compositions of the second catalyst layer and the first catalyst layer may be the same or different, and the thicknesses of the second catalyst layer and the first catalyst layer may be the same or different. Various methods commonly used in the art, such as transfer printing, direct coating, brushing, ultrasonic spraying, and vacuum adsorption, can be used to coat the second catalyst layer onto the second surface. After the double-sided CCM produced through the above steps is dried, the flatness of the double-sided CCM is checked in step 250. The method in Figure 4 includes only the steps of preparing the first catalyst layer, the test material, and the second catalyst layer, but those skilled in the art will understand that the CCM may include other structures, and therefore the process test may also include steps for producing other structures, such as steps for producing other layer structures.

[0024] By selecting a material suitable for the CCM process using the method shown in Figure 2, and confirming the flatness of the double-sided CCM in the process test shown in Figure 4, it was found that a material with a high coefficient of friction is used for fixing the polymer film. After the coating process, the flatness of the double-sided CCM is improved. This result indicates that the flatness of the CCM has a significant positive correlation with the coefficient of friction of the material.

[0025] When polymer films (especially perfluorosulfonate ion films) are fabricated by transfer printing, the transfer temperature reaches a high temperature of 210°C (200°C higher than the melting point of the perfluorosulfonate ion film). Studies have shown that when the temperature exceeds the glass transition temperature (100-110°C), the polymer chains reorganize or migrate, resulting in structural changes and a decrease in the properties of the polymer film. High temperatures destroy the structure of the polymer film, so it is necessary to avoid high temperatures during the CCM process. Unlike conventional techniques, the materials selected by the method of the present invention can be applied to room-temperature CCM processes, solving the high-temperature limitations of conventional processes. The method of the present invention uses the coefficient of friction of the material as the basis for determining the flatness of the CCM and completely solves the problems of swelling and deformation of the CCM using existing processes in this field without damaging the polymer film structure. Since it is not necessary to impose various limitations on existing processes, the present invention can improve the surface uniformity and flatness of the CCM with the lowest possible constraints.

[0026] On the other hand, the method of the present invention overcomes the yield problems of low catalyst layer utilization and multiple catalyst coating caused by conventional methods. Since the surface of a CCM made of a material with a high coefficient of friction is flat, it is beneficial to coat the catalyst layer thickly. As shown in Table 2, as the thickness of the mold increases, the thickness of the first and second catalyst layers also increases, and surface folds do not occur. In a double-sided CCM manufactured according to the method of the present invention, the thickness of the first and second catalyst layers is 5 to 80 μm, respectively. Specifically, for example, if the mold thickness is 100 μm, the thickness of the first catalyst layer is 17.0 μm and the thickness of the second catalyst layer is 17.6 μm. For example, if the mold thickness is 200 μm, the thickness of the first catalyst layer is 37.3 μm and the thickness of the second catalyst layer is 36.6 μm. If the mold thickness is 300 μm, the thickness of the first catalyst layer is 41.3 μm and the thickness of the second catalyst layer is 60.0 μm. If the mold thickness is 400 μm, the thickness of the first catalyst layer will be 61.0 μm and the thickness of the second catalyst layer will be 76.3 μm.

[0027] [Table 2]

[0028] In another aspect of the present invention, a method for obtaining CCM is provided. Figure 5 is a flowchart of method 300 for obtaining CCM according to the present invention. First, in step 310, a friction force test is performed on the test material to obtain the coefficient of friction of the test material. In step 320, it is checked whether the coefficient of friction is between 0.1 and 15. If the coefficient of friction is between 0.1 and 15, in step 330 the test material is used in the CCM process. Conversely, if the coefficient of friction is not in the range of 0.1 to 15, it means that the test material is not suitable for the CCM process. In a preferred embodiment of the present invention, the friction force test is ASTM D1894, and the coefficient of friction is the static coefficient of friction. The range of the coefficient of friction used in step 320 may be set to a different range as needed, such as any range between 0.1 and 15, preferably between 1 and 15, more preferably between 5 and 15, as needed.

[0029] As used in this invention, the term "CCM process" refers to various processes in the art that can be used to manufacture CCM, preferably processes for manufacturing double-sided CCM. For example, a CCM process may be one of self-transfer printing, roll-to-roll (R2R) coating, brush coating, ultrasonic spray coating, and vacuum adsorption. In this CCM process, a test material is combined with at least one catalyst layer of the double-sided CCM to improve the flatness of the double-sided CCM. According to this invention, materials having a coefficient of friction of 0.1 to 15 and suitable for the CCM process include silicone, rubber, silicone rubber, polymers, metals, metal oxides, and combinations thereof. Preferably, materials suitable for the CCM process include silicone, rubber, silicone rubber, polymers, and combinations thereof. Furthermore, materials suitable for the CCM process include silicone, rubber, silicone rubber, and combinations thereof.

[0030] The method 300 for obtaining CCM of the present invention may have other embodiments. In step 310, the means for obtaining the coefficient of friction of the test material is not limited to a friction force test, and the coefficient of friction of the test material can be obtained by other methods. For example, the coefficient of friction of the test material can be obtained from a known database, product description, or publicly available information. If the coefficient of friction of the test material is obtained by a method other than a friction force test, step 310 in Figure 5 is omitted, and steps 320 and 330 are performed in order to confirm whether the coefficient of friction of the test material is between 0.1 and 15, and the test material is used in the CCM process.

[0031] Specific embodiments of the present invention will be described below.

[0032] Example 1 - Friction Test (ASTM D1894) First, two test materials of different sizes are prepared as test samples. The sample sizes are 250 mm × 130 mm and 63.5 mm × 63.5 mm, respectively. The two test samples are placed horizontally on top of each other, and a 200 g weight is pulled at a speed of 150 mm / min. The tensile force Fs required to pull the weight (i.e., the static friction force fs between the two test samples) is measured. Since the weight applies a normal positive pressure W to the test samples, the static friction coefficient μs is equal to the ratio of the static friction force fs to the normal positive pressure W, according to the friction force formula (fs = W × μs). The larger the tensile force Fs, the larger the measured static friction coefficient μs will be.

[0033] Example 2 - Process Test In this process test, the perfluorosulfonate ion membrane Nafion 212 (manufactured by DuPont) was used as the proton exchange membrane for the CCM. The product parameters are as follows: thickness 50.8 μm, density 100 g / m2, specification 61 cm*L, conductivity 0.083 S / cm, ion exchange capacity 0.95~1.01 milliequivalents / g. The ion exchange capacity 212 has a coverslip membrane on the top surface and a backing film on the bottom surface.

[0034] Step 1: Remove the coverslip film from the top surface of the Nafion212 film. Step 2: Coat the top surface with a first catalyst layer. The slurry components of the first catalyst layer are 1.8 grams of carbon powder, 4 grams of perfluorosulfonic acid solution D520, and 6 grams of isopropyl alcohol (IPA). Dry the coated first catalyst layer at 70°C to obtain a first catalyst layer with a thickness of 30 μm. Step 3: Cover the first catalyst layer with the test material. Step 4: 1.288 kgf / cm² at room temperature 2 The lamination process is performed under pressure to bond the test material to the first catalyst layer. Step 5: Remove the backing film from the underside of the Nafion212 film. Step 6: Coat the bottom surface with the second catalyst layer. The slurry components of the second catalyst layer are 1.8 grams of carbon powder, 4 grams of perfluorosulfonic acid solution D520, and 6 grams of IPA. Dry the coated second catalyst layer at 70°C to obtain a second catalyst layer with a thickness of 30 μm. Step 7: Observe whether the surface of the manufactured double-sided CCM is flat.

[0035] By using the method for determining the flatness of a CCM and the method for obtaining a CCM of the present invention, it is possible to manufacture a CCM under the lowest process constraints, completely solve the problems of swelling and deformation of the CCM, and increase the thickness of the catalyst layer.

[0036] From the embodiments described above, at least the following forms can be understood. [1] According to one embodiment, a method for determining the flatness of a catalyst coating film (CCM), wherein the catalyst coating film has a test material, and the method includes the steps of: performing a friction force test on the test material to obtain the coefficient of friction of the test material; comparing the coefficient of friction with a predetermined range of 0.1 to 15; and determining the flatness of the catalyst coating film including the test material by comparing the coefficient of friction with the predetermined range. [2]According to embodiment [1], the catalyst coating film comprises a polymer film and at least one catalyst layer, the test material is used to combine with the at least one catalyst layer in the catalyst coating film, and the flatness and the coefficient of friction are positively correlated. [3] According to form [1] or [2], the predetermined range is 1 to 15. [4] According to form [1] or [2], the predetermined range is 5 to 15. [5] According to any of the embodiments [1] to [4], if the coefficient of friction is within the predetermined range, a processing test is performed on the test material, the processing test comprising the steps of: coating a first catalyst layer on the first surface of the polymer film; placing the test material on the first catalyst layer; applying pressure to the first catalyst layer on which the test material is placed to bond the test material with the first catalyst layer; coating a second catalyst layer on the second surface of the polymer film to obtain catalyst coating films on both sides; and confirming the flatness of the catalyst coating films on both sides. [6] In one embodiment, a catalyst coating is obtained comprising the steps of: performing a friction force test on a test material to obtain a coefficient of friction of the test material; and, if the coefficient of friction is 0.1 to 15, using the test material in a catalyst coating manufacturing process to obtain a catalyst coating. [7]According to the form[6], the test material is one selected from the group consisting of silicone, rubber, silicone rubber, polymer, metal and metal oxide. [8]According to form [6] or [7], the catalyst coating film is a double-sided catalyst coating film, and the test material is bonded to at least one catalyst layer of the double-sided catalyst coating film to improve the flatness of the double-sided catalyst coating film. [9]According to any of the forms [6] to [8], the catalyst coating film manufacturing process is one selected from the group consisting of a transfer printing method, a roll-to-roll (R2R) coating method, a brush coating method, an ultrasonic spray coating method, and a vacuum adsorption method.

[10] According to one embodiment, the method includes the steps of obtaining the coefficient of friction of a test material, confirming whether the coefficient of friction is in the range of 0.1 to 15, and if the coefficient of friction is in the range of 0.1 to 15, using the test material in a catalyst coating manufacturing process to obtain a catalyst coating.

[11] According to the embodiment

[10] , the coefficient of friction is determined by a frictional force test of the test material. Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications or improvements can be made to the above embodiments. It will be clear from the claims that such modified or improved forms may also be included in the technical scope of the present invention. [Explanation of Symbols]

[0037] 10: CCM 12: Polymer membrane 14: Anode catalyst layer 16: Cathode catalyst layer 17: Gas diffusion layer 100, 300: Method 110, 120, 130, 210, 220, 230, 240, 250, 310, 320, 330: Steps

Claims

1. A method for determining the flatness of a catalyst coating film (CCM), wherein the catalyst coating film has a test material, and the method is The steps include: performing a friction force test on the test material in order to obtain the coefficient of friction of the test material; The steps include comparing the coefficient of friction with a predetermined range of 0.1 to 15, A method comprising the step of determining the flatness of the catalyst coating film containing the test material by comparing the coefficient of friction with the predetermined range.

2. The catalyst coating film comprises a polymer film and at least one catalyst layer, and the test material is used to combine with the at least one catalyst layer in the catalyst coating film. The method according to claim 1, characterized in that the flatness and the coefficient of friction are positively correlated.

3. The method according to claim 1, characterized in that the predetermined range is 5 to 15.

4. If the coefficient of friction is within the predetermined range, a processing test is performed on the test material. The aforementioned processing test is The steps include coating the first surface of the polymer film with a first catalyst layer, The steps include placing the test material in the first catalyst layer, The steps include applying pressure to the first catalyst layer on which the test material is placed to bond the test material with the first catalyst layer, The process involves coating the second surface of the polymer film with a second catalyst layer to obtain a catalyst coating film on both sides, The method according to claim 2, characterized by comprising the step of confirming the flatness of the catalyst coating films on both sides.

5. The steps include: performing a friction force test on the test material to obtain the coefficient of friction of the test material; A method for obtaining a catalyst coating film, comprising the steps of: using the test material in a catalyst coating film manufacturing process to obtain a catalyst coating film when the coefficient of friction is 0.1 to 15.

6. The aforementioned test material is one selected from the group consisting of silicone, rubber, silicone rubber, polymer, metal, and metal oxide. The catalyst coating film is a double-sided catalyst coating film. The test material bonds to at least one catalyst layer of the catalyst coating film on both sides to improve the flatness of the catalyst coating film on both sides. The method according to claim 5, characterized in that the catalyst coating film manufacturing process is one selected from the group consisting of a transfer printing method, a roll-to-roll (R2R) coating method, a brush coating method, an ultrasonic spray coating method, and a vacuum adsorption method.

7. Steps to obtain the coefficient of friction of the test material, The steps include: confirming whether the coefficient of friction is in the range of 0.1 to 15; A method for obtaining a catalyst coating film, comprising the step of using the test material in a catalyst coating film manufacturing process to obtain a catalyst coating film if the coefficient of friction is in the range of 0.1 to 15.

8. The method according to claim 7, characterized in that the coefficient of friction is determined by a frictional force test of the test material.

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