Method for determining flatness of coated catalyst film (CCM) and method for obtaining CCM

Abstract

The invention discloses a method for obtaining a coating catalyst film (CCM). The method comprises the following steps: obtaining a friction coefficient of a material to be detected; determining whether the friction coefficient is between 0.1 and 15; and if so, applying the to-be-tested material to a CCM process to obtain the CCM.

Description

Technical Field

[0001] This invention relates to a method for determining the flatness of a CCM and a method for obtaining a CCM, particularly to a method for obtaining a flat CCM based on the material's coefficient of friction. Background Technology

[0002] A fuel cell is an energy conversion device that directly converts the chemical energy stored in hydrogen fuel and oxidant into electrical energy through an electrochemical reaction. Fuel cells are characterized by high energy conversion efficiency and zero emissions, and are considered one of the most promising solutions to the energy crisis and environmental pollution, particularly in transportation (such as automobiles, ships, and backup power). Due to these outstanding features, the development and application of fuel cell technology have received significant attention from governments and enterprises worldwide.

[0003] The coated catalyst membrane (CCM) is a crucial component of a fuel cell. Its primary preparation method involves coating a polymer membrane with a catalyst slurry and then drying it to form the CCM. When coating both sides of the polymer membrane with the catalyst slurry, the presence of alcohol solvents (such as methanol, ethanol, propanol, isopropanol, n-propanol, or glycerol) can cause swelling of the polymer membrane, negatively impacting its quality.

[0004] Ensuring the surface uniformity and flatness of CCMs has always been a key research and development area in this field. Although there are many methods for preparing CCMs (such as transfer printing, roll-to-roll (R2R) coating, brush coating, ultrasonic spraying, and vacuum adsorption), these methods are subject to various process limitations, resulting in their own drawbacks. This means that the problem has not yet been completely solved.

[0005] To address the issues of CCM swelling and deformation, it is desirable to obtain a smooth CCM with minimal process constraints, thereby effectively improving the quality of the CCM. Summary of the Invention

[0006] This invention provides a method for determining the flatness of a CCM and a method for obtaining a CCM. The method uses the coefficient of friction of the material to be tested as the basis for judging the flatness of the CCM, and applies a material with a high coefficient of friction to the CCM process, thereby obtaining a flat CCM.

[0007] In one aspect of the present invention, a method for determining the flatness of a CCM is disclosed, wherein the CCM comprises a test material, the method comprising: subjecting the test material to a friction test to obtain a coefficient of friction of the test material; comparing the coefficient of friction with a predetermined range between 0.1 and 15; and determining the flatness of the CCM comprising the test material by means of the comparison result between the coefficient of friction and the predetermined range.

[0008] In another aspect of the present invention, a method for obtaining CCM is disclosed, comprising: subjecting a test material to a friction test to obtain a coefficient of friction of the test material; and when the coefficient of friction is between 0.1 and 15, using the test material in a CCM process to obtain the CCM.

[0009] The present invention further discloses a method for obtaining CCM, comprising: obtaining a coefficient of friction of a test material; confirming whether the coefficient of friction is between 0.1 and 15; and if so, using the test material in a CCM process to obtain the CCM. Attached Figure Description

[0010] The objectives and advantages of this invention can be more fully understood through the following figures and detailed description:

[0011] Figure 1 is a cross-sectional view of the CCM in the prior art;

[0012] Figure 2 This is a flowchart of a method for determining the flatness of CCM according to the present invention;

[0013] Figure 3 This shows the relationship between the coefficient of friction of different materials and the flatness of double-sided CCM;

[0014] Figure 4 This is a flowchart of the process testing for this invention; and

[0015] Figure 5 This is a flowchart of the method for obtaining CCM according to the present invention. Detailed Implementation

[0016] The invention presented in this case will be fully understood by the following embodiments, which will enable those skilled in the art to carry it out. However, the implementation of this case is not limited to its implementation form by the following embodiments. Those skilled in the art can still deduce other embodiments based on the spirit of the disclosed embodiments, and all such embodiments should be within the scope of this invention.

[0017] 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; this structure is called a coated catalyst membrane (CCM). As used herein, "polymer membrane" includes cation exchange membranes (PEM), anion exchange membranes (AEM), and perfluorosulfonic acid ion exchange membranes. This invention allows for the selection of polymer membranes based on actual needs to transport different ions.

[0018] Figure 1 shows a cross-sectional view of a prior art CCM 10. The CCM 10 is a double-sided CCM, comprising a polymer membrane 12, an anode catalyst layer 14 coated on the upper surface of the polymer membrane 12, and a cathode catalyst layer 16 coated on the lower surface of the polymer membrane 12. Furthermore, the CCM 10 includes a gas diffusion layer 17 disposed on the anode side and a gas diffusion layer 18 disposed on the cathode side, serving to support the catalyst layers, collect current, conduct gas, and discharge the reaction product water.

[0019] 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, assuming 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 disposed at any suitable location in the CCM, preferably bonded to at least one catalyst layer in the CCM. For example, the test material can be bonded to the anodic catalyst layer 14, the cathode catalyst layer 16, or both shown in FIG. 1.

[0020] Figure 2 This is a flowchart of a method 100 for determining the flatness of a CCM according to the present invention. In step 110, a friction test is performed on the test material to obtain the coefficient of friction of the test material. In step 120, the coefficient of friction is compared with a predetermined range of 0.1-15. In step 130, the flatness of the CCM containing the test material is determined by the comparison result of the coefficient of friction with the predetermined range. The friction test used in the present invention includes various methods for obtaining the coefficient of friction of the test material, such as methods for obtaining the static or dynamic coefficient of friction between two identical test materials. In a preferred embodiment of the present invention, the friction test is ASTM D1894, and the coefficient of friction is the static coefficient of friction. However, it should be understood that the friction test used in the present invention is not limited to the method in the preferred embodiment. Furthermore, those skilled in the art should understand that when performing friction tests on different test materials, the same test method should be used to ensure that the coefficient of friction of different test materials has a consistent standard.

[0021] exist Figure 2 In step 120, different predetermined ranges can be set according to actual needs. For example, the predetermined range can be a coefficient of friction ranging from 0.1 to 15, preferably from 1 to 15, and more preferably from 5 to 15. To establish the relationship between the coefficient of friction of the test material and the flatness of the CCM, the present invention conducted experiments on different test materials as shown in Table 1. The experiments in Table 1 used the ASTM D1894 friction test to obtain the coefficient of friction of different test materials. Different test materials were used to prepare double-sided CCMs, and the surface flatness of each prepared CCM was observed. In this experiment, the test material was formed into a substrate and used to laminate with one of the catalyst layers in the double-sided CCM under a pressure of 1.288 kgf / cm2.

[0022] Table 1

[0023]

[0024] As shown in Table 1, materials 1 to 5 each have different coefficients of friction. When materials 1 to 5 are used as substrate materials and laminated with the catalyst layer in the double-sided CCM, the experimental results show that the higher the coefficient of friction, the smoother the resulting double-sided CCM. Figure 3 As shown, the double-sided CCMs made from materials 1 and 2 still exhibit surface defects of swelling and bulging. The double-sided CCMs made from materials 3 to 5 have smooth surfaces without swelling, bulging, or creases. These experimental results can be used as the basis for this invention. Figure 2 The basis for determining the predetermined range in step 120 can also serve as a reference for determining the flatness of the CCM in step 130. For example, the predetermined range in step 120 can be set to a friction coefficient between 0.1 and 15 based on known experimental results. In step 130, when the friction coefficient of the material to be tested is within this predetermined range, it is determined that the CCM containing the material to be tested has a flat surface.

[0025] The method for determining CCM flatness using this invention allows for the selection of suitable materials for preparing double-sided CCMs. For unknown test materials, if the coefficient of friction of the test material falls within a predetermined range, further process testing can be performed to determine the surface characteristics of the CCM containing the test material. Figure 4 This is a flowchart of the process testing for the present invention, although Figure 4 The process testing described herein is a method for preparing double-sided CCMs; however, it should be understood that materials screened using the method for determining CCM flatness in this invention can also be used to prepare CCMs with other structures. That is, Figure 4The process tests described are merely examples, and those skilled in the art can adjust the steps of the process tests according to actual needs.

[0026] Please see Figure 4 First, in step 210, a polymer film is provided, and a first catalyst layer is coated on a first surface of the polymer film. Preferably, the polymer film is a perfluorosulfonic acid film, and the first catalyst layer is a mixture comprising, for example, toner, noble metals and metal oxides, perfluorosulfonic acid resin, alcohol solvent, and water. The first catalyst layer can be coated on the first surface using various methods commonly used in the art, such as transfer printing, direct coating, brushing, ultrasonic spraying, or vacuum adsorption. In step 220, the catalyst layer, which has been coated by... Figure 2 The test material selected by the method is placed on the first catalyst layer, wherein the test material overlaps with the first catalyst layer at least partially. For example, the test material may be placed on the first catalyst layer in a layered structure or cover a part of the first catalyst layer.

[0027] In step 230, pressure is applied to the first catalyst layer on which the test material is disposed, causing the test material to bond with the first catalyst layer. The pressure applied to the first catalyst layer in this invention can be performed under various environments, such as room temperature pressing, hot pressing, vacuum pressing, etc. In a preferred embodiment of this invention, the pressure applied to the first catalyst layer is either room temperature pressing or vacuum pressing. In step 230, the pressure applied to the first catalyst layer is between 0 and 380 kgf / cm². 2 Preferably 0–50 kgf / cm 2 More preferably 0–10 kgf / cm 2 For example, during the room temperature lamination process, the pressure applied to the first catalyst layer is 1.288 kgf / cm². 2 .

[0028] In step 240, a second catalyst layer is coated on the second surface of the polymer film to obtain a double-sided CCM. Depending on the actual needs of the double-sided CCM, the composition of the second catalyst layer and the first catalyst layer can be the same or different, and their thicknesses can also be the same or different. The second catalyst layer can be coated onto the second surface using various methods commonly used in the art, such as transfer printing, direct coating, brushing, ultrasonic spraying, or vacuum adsorption. After drying the double-sided CCM prepared through the above steps, in step 250, the flatness of the double-sided CCM is checked. Although in Figure 4 The method only involves the steps of preparing the first catalyst layer, the test material, and the second catalyst layer. However, those skilled in the art should understand that the CCM may also include other structures. Therefore, process testing may also include steps of preparing other structures, such as steps of preparing other layer structures.

[0029] Through use Figure 2The method screens out materials suitable for CCM processes and uses Figure 4 Process testing confirmed the flatness of the double-sided CCM, revealing that using a material with a higher coefficient of friction to fix the polymer film during the process resulted in better flatness of the double-sided CCM after the double-sided coating step. This result shows a significant positive correlation between the flatness of the CCM and the coefficient of friction of the material.

[0030] When preparing CCMs with polymer films (especially perfluorosulfonic acid ion exchange films) using the transfer method, the transfer temperature can reach as high as 210°C (higher than the melting point of perfluorosulfonic acid ion exchange films, 200°C). Studies have shown that when the temperature exceeds the glass transition temperature (100–110°C), polymer chains undergo recombination or migration, leading to structural changes and a decrease in the properties of the polymer film. Since high temperatures will damage the structure of the polymer film, high temperatures should be avoided in the CCM process. Unlike conventional techniques, the materials screened using the method of this invention can be applied to room-temperature CCM processes, overcoming the high-temperature limitations of traditional processes. The method of this invention uses the coefficient of friction of the material as the basis for determining the flatness of the CCM, completely solving the problems of CCM swelling and deformation without damaging the polymer film structure, using existing processes in the art. Because it does not require setting various limiting conditions for existing processes, this invention improves the surface uniformity and flatness of CCMs with minimal limitations.

[0031] On the other hand, the method of the present invention also overcomes the problems of low catalyst layer utilization and low yield due to multiple catalyst coatings caused by conventional methods. Because the CCM surface made from a material with a high coefficient of friction is smooth, it is beneficial to coat a thicker catalyst layer. As shown in Table 2, as the mold thickness increases, the thickness of the first and second catalyst layers also increases, without surface wrinkling. The double-sided CCM prepared according to the method of the present invention has each of the first and second catalyst layers having a thickness between 5 and 80 μm. Specifically, when the mold thickness is 100 μm, the thicknesses of the first catalyst layer and the second catalyst layer are, for example, 17.0 μm and 17.6 μm, respectively; when the mold thickness is 200 μm, the thicknesses of the first catalyst layer and the second catalyst layer are, for example, 37.3 μm and 36.6 μm, respectively; when the mold thickness is 300 μm, the thicknesses of the first catalyst layer and the second catalyst layer are, for example, 41.3 μm and 60.0 μm, respectively; and when the mold thickness is 400 μm, the thicknesses of the first catalyst layer and the second catalyst layer are, for example, 61.0 μm and 76.3 μm, respectively.

[0032] Table 2 Data on Coating Catalyst Layer Thickness Control

[0033]

[0034] In another aspect of the present invention, a method for obtaining CCM is provided. Figure 5This is a flowchart of a method 300 for obtaining CCM according to the present invention. First, in step 310, the material to be tested is subjected to a friction test to obtain the coefficient of friction of the material. In step 320, it is determined whether the coefficient of friction is between 0.1 and 15. If the coefficient of friction is between 0.1 and 15, then in step 330, the material to be tested is used in the CCM process. Conversely, if the coefficient of friction is not between 0.1 and 15, it means that the material to be tested is not suitable for the CCM process. In a preferred embodiment of the present invention, the friction 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 can be set to different ranges according to actual needs, for example, any range between 0.1 and 15, preferably any range between 1 and 15, and more preferably any range between 5 and 15.

[0035] The term "CCM process" as used in this invention refers to various processes in the art that can be used to prepare CCMs, preferably processes for preparing double-sided CCMs. For example, the CCM process can be selected from one of the following: transfer printing, roll-to-roll (R2R) coating, brush coating, ultrasonic spraying, and vacuum adsorption. In this CCM process, the material to be tested is bonded to at least one catalyst layer in the double-sided CCM to improve the flatness of the double-sided CCM. According to the invention, materials with a coefficient of friction between 0.1 and 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. More specifically, materials suitable for the CCM process include silicone, rubber, silicone rubber, and combinations thereof.

[0036] The method 300 for obtaining the coefficient of friction (CCM) of the present invention can be implemented in another way. In step 310, the means of obtaining the coefficient of friction of the material under test is not limited to friction force testing; other methods can also be used to obtain the coefficient of friction of the material under test. For example, the coefficient of friction of the material under test may be obtained from a known database, product specifications, or any publicly available information. If the coefficient of friction of the material under test is obtained by means other than friction force testing, this step is omitted. Figure 5 Step 310 is followed by steps 320 and 330 to confirm whether the friction coefficient of the material to be tested is between 0.1 and 15 and to use the material to be tested in the CCM process.

[0037] The following describes specific embodiments of the present invention.

[0038] Example 1 - Friction Test (ASTM D 1894)

[0039] First, prepare two test samples of different sizes: 250mm x 130mm and 63.5mm x 63.5mm, respectively. Place the two samples horizontally, overlapping each other, and apply a 200g weight to each sample. Pull the weight at a speed of 150mm / min and measure the pulling force Fs (i.e., the static friction force fs between the two test samples). Since the weight provides a normal force W on the test sample, according to the friction formula (fs = W x μs), the static friction coefficient μs is equal to the ratio of the static friction force fs to the normal force W. The larger the pulling force Fs, the larger the measured static friction coefficient μs.

[0040] Example 2 - Process Testing

[0041] In this process test, the perfluorosulfonic acid ion exchange membrane Nation 212 (manufactured by DuPont) was used as the proton exchange membrane in the CCM. The product parameters are as follows: thickness 50.8 μm; density 100 g / m³. 2 Specifications: 61cm*L; Conductivity: 0.083S / cm; Ion exchange capacity: 0.95-1.01meq / g. Nafion 212 has a cover sheet on the upper surface and a backing film on the lower surface.

[0042] Step 1: Remove the cover film from the top surface of the Nafion 212 membrane;

[0043] Step 2: Coat the upper surface with a first catalyst layer. The slurry composition of the first catalyst layer is 1.8 g of toner, 4 g of perfluorosulfonic acid solution D52O, and 6 g of isopropanol (IPA). Dry the coated first catalyst layer at 70°C to obtain a first catalyst layer with a thickness of 30 μm.

[0044] Step 3: Cover the material to be tested onto the first catalyst layer;

[0045] Step 4: At room temperature, at 1.288 kgf / cm² 2 The pressure is used to bond the material to be tested to the first catalyst layer;

[0046] Step 5: Remove the backing film from the underside of the Nafion 212 membrane;

[0047] Step 6: Applying a second catalyst layer to the lower surface. The slurry composition of the second catalyst layer is 1.8 g of carbon powder, 4 g of perfluorosulfonic acid solution D52O, and 6 g of IPA. The coated second catalyst layer is dried at 70°C to obtain a second catalyst layer with a thickness of 30 μm; and

[0048] Step 7: Observe whether the surface of the double-sided CCM is flat.

[0049] By using the method for determining the flatness of CCM and the method for obtaining CCM in this invention, CCM can be prepared with minimal process constraints, completely solving the problem of CCM swelling and deformation, while increasing the thickness of the catalyst layer.

[0050] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Those skilled in the art can make modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims. Furthermore, no embodiment or claim of the present invention is required to achieve all the objectives, advantages, or features disclosed in the present invention. In addition, the abstract and headings are merely for assisting in patent document searches and are not intended to limit the scope of the invention.

[0051] Symbol Explanation

[0052] 10: Coated Catalyst Film (CCM)

[0053] 12: Polymer membrane

[0054] 14: Anode catalyst layer

[0055] 16: Cathode catalyst layer

[0056] 17, 18: Gas diffusion layer

[0057] 100, 300: Methods

[0058] 110, 120, 130, 210, 220, 230, 240, 250, 310, 320, 330: Steps

Claims

1. A method for determining the flatness of a coated catalyst film (CCM), wherein the CCM comprises a material to be tested, the method comprising: The friction force test is performed on the material to be tested to obtain the coefficient of friction of the material to be tested. The coefficient of friction is compared with a predetermined range of 0.1-15; as well as The flatness of the CCM containing the test material is determined by comparing the friction coefficient with the predetermined range, wherein the flatness of the CCM is positively correlated with the friction coefficient of the test material.

2. The method according to claim 1, wherein the CCM comprises a polymer membrane and at least a catalyst layer, and the test material is used to bond with the at least catalyst layer in the CCM.

3. The method according to claim 1, wherein the predetermined range is within the range of 1-15.

4. The method according to claim 1, wherein the predetermined range is within the range of 5-15.

5. The method according to claim 2, further comprising: When the friction coefficient is within the predetermined range, the material to be tested is subjected to process testing, which includes the following steps: A first catalyst layer is coated on the first surface of the polymer film; The material to be tested is placed on the first catalyst layer; Pressure is applied to the first catalyst layer on which the test material is disposed, so that the test material bonds to the first catalyst layer; A second catalyst layer is coated on the second surface of the polymer film to obtain a double-sided CCM; and Confirm the flatness of the double-sided CCM.

6. A method for obtaining a coated catalyst film (CCM) with flatness, comprising: The friction force of the material to be tested is used to obtain the coefficient of friction of the material to be tested. as well as When the coefficient of friction is between 0.1 and 15, the material to be tested is used in a CCM process to obtain the CCM, wherein the flatness of the CCM is positively correlated with the coefficient of friction of the material to be tested.

7. The method according to claim 6, wherein the test material is selected from the group consisting of silicone, rubber, silicone rubber, polymers, metals and metal oxides.

8. The method according to claim 6, wherein the CCM is a double-sided CCM, and the test material is bonded to at least a catalyst layer in the double-sided CCM to improve the flatness of the double-sided CCM.

9. The method according to claim 6, wherein the CCM process is selected from one of the group consisting of transfer printing, roll-to-roll (R2R) coating, brush coating, ultrasonic spraying, and vacuum adsorption.

10. A method for obtaining a coated catalyst film (CCM) with flatness, comprising: Obtain the friction coefficient of the material to be tested; Confirm whether the coefficient of friction is between 0.1 and 15; as well as Thus, the test material is used in a CCM process to obtain the CCM, wherein the flatness of the CCM is positively correlated with the coefficient of friction of the test material.

11. The method of claim 10, wherein the coefficient of friction is obtained by subjecting the material to be tested to a frictional force test.

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