Fuel cell catalyst layer and preparation method thereof
By using a variety of boiling-point organic solvents and temperature gradient drying technology, a uniform and fine catalyst layer was prepared, which solved the problem of uneven pore structure in the PEMFC catalyst layer, improved the durability and electrochemical stability of the support, and enhanced the power generation performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-19
- Publication Date
- 2026-03-13
AI Technical Summary
The non-uniform pore structure of the catalyst layer in existing proton exchange membrane fuel cells (PEMFCs) results in insufficient carrier durability and electrochemical stability, failing to meet the requirements for large-scale applications.
Catalyst slurry was prepared using a variety of organic solvents with different boiling points, and the temperature gradient of each oven was controlled by a multi-stage drying device to ensure the evaporation of solvent gradients and avoid the formation of large pores, thus producing a uniform and fine catalyst layer.
This improved the carrier durability and long-term electrochemical stability of the membrane electrode, thereby enhancing the power generation performance of PEMFC.
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Figure CN121662835A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of fuel cell technology, and more specifically, to a fuel cell catalyst layer and its preparation method. Background Technology
[0002] Proton exchange membrane fuel cells (PEMFCs), as a highly promising energy conversion device, have attracted widespread attention against the backdrop of increasing global demand for green energy. PEMFCs can directly convert the chemical energy of fuel (usually hydrogen) and oxidant (usually oxygen or air) into electrical energy. At the anode, hydrogen undergoes an oxidation reaction under the action of a catalyst, decomposing into protons and electrons. Protons are conducted to the cathode through the proton exchange membrane, while electrons flow to the cathode through an external circuit, forming an electric current that provides power to an external load. At the cathode, oxygen undergoes a reduction reaction with protons and electrons to produce water. This process makes PEMFCs highly efficient and zero-emission, making them an ideal green energy technology.
[0003] The core component of a PEMFC, the membrane electrode assembly (MEA), includes the anode and cathode catalyst layers, anode and cathode gas diffusion layers, and a proton exchange membrane. As the site of electrochemical reactions, the structure of the anode and cathode catalyst layers affects the transport resistance of reactant gases and product water, the proton transport impedance, and the size of the three-phase interface at the catalytic reaction site, thus having a decisive impact on the power generation performance of the PEMFC. The anode and cathode catalyst layers of a PEMFC typically consist of a catalyst and an ionomer. Specifically, the catalyst and ionomer are uniformly dispersed in a solvent to prepare a catalyst slurry, which is then coated onto a base membrane and dried to form the catalyst layer. The composition of the catalyst slurry and the coating and drying processes both affect the structure of the catalyst layer.
[0004] Currently, there is still a need to further improve the power generation performance of PEMFCs to meet the requirements of large-scale applications. Specifically, the structure of the catalyst layer still needs to be further optimized to improve the power generation performance of PEMFCs. Summary of the Invention
[0005] This application provides a fuel cell catalyst layer and its preparation method, which can make the pore structure of the catalyst layer more uniform and dense, and further improve the support durability and long-term electrochemical stability of the membrane electrode of PEMFC.
[0006] The embodiments of this application are implemented as follows: In a first aspect, this application provides a method for preparing a fuel cell catalyst layer, comprising the following steps: S1, mixing a catalyst, a solvent, and an ionomer resin to form a catalyst slurry; wherein the solvent comprises an organic solvent and water, the organic solvent comprising three organic solvents with boiling points of 70-100℃ and an organic solvent with boiling points of 100-120℃, wherein the boiling point difference between any two adjacent organic solvents with boiling points of 70-100℃ is in the range of 7-15℃; S2, applying the catalyst slurry onto a base membrane, and then sending it into a drying device for drying to form a catalyst layer; wherein the drying device comprises a multi-stage oven, the number of stages of the oven being the same as the types of organic solvents and water, the highest temperature of the oven during the drying process being 20-30℃ lower than the boiling point of the organic solvents with boiling points of 100-120℃, the temperature of the multiple stages of the oven increasing sequentially, and the temperature difference between two adjacent stages of the oven being 4-9℃.
[0007] In the above technical solution, the method for preparing the fuel cell catalyst layer of this application uses a variety of organic solvents with different boiling points to prepare catalyst slurry, controls the boiling point difference of each organic solvent within a suitable range, and controls the temperature of each oven section within a suitable range during the drying process. This allows the solvents with different boiling points to evaporate in a gradient during coating and drying, avoiding the problem of a large amount of solvent evaporating in a short time and forming large pores. The catalyst layer has a more uniform and fine pore structure, effectively improving the durability of the membrane electrode carrier and the long-term electrochemical stability.
[0008] In some possible implementations, in step S1, the boiling point difference between any two adjacent organic solvents among the three organic solvents with boiling points of 70-100°C ranges from 9-15°C.
[0009] In the above technical solution, controlling the boiling point difference of each organic solvent within the above range can further improve the uniformity of the catalyst layer pore structure.
[0010] In some possible implementations, in step S1, the organic solvent with a boiling point of 100-120°C has a boiling point difference of more than 7°C from that of water.
[0011] In some possible implementations, in step S2, the highest temperature of the oven during the drying process is 24-28°C lower than the boiling point of the organic solvent with a boiling point of 100-120°C, and the temperature difference between two adjacent oven sections is 5-7°C.
[0012] In the above technical solution, when the temperature of each section of the oven is controlled within the above range, the evaporation rate of each solvent can be better controlled, and the uniformity of the pore structure of the catalyst layer can be further improved.
[0013] In some possible implementations, in step S2, the base membrane is a proton exchange membrane or a transfer membrane.
[0014] In some possible implementations, in step S2, the base film is dried for 20-60 seconds in each section of the oven during the drying process.
[0015] In some possible embodiments, the organic solvent with a boiling point of 70-100°C is selected from at least one of ethanol, n-propanol, isopropanol, sec-butanol, tert-butanol, n-propyl ether, methyl n-butyl ether, butanone, ethyl acetate, ethylene glycol dimethyl ether, trifluoroacetic acid, tetrahydropyran, propionitrile, acetonitrile, ethyl tert-butyl ether, 1,3-dioxolane, methyl isopropyl ketone, and 2,3-butanedione; and / or the organic solvent with a boiling point of 100-120°C is selected from at least one of n-butanol, isobutanol, 3-pentanol, and neopentanol.
[0016] In some possible implementations, the catalyst is selected from at least one of platinum-carbon catalysts and platinum alloy catalysts.
[0017] In some possible implementations, the ionomer resin is selected from any one or more of perfluorosulfonic acid resins, partially fluorinated sulfonic acid resins, polyetheretherketone sulfonic acid resins, and polystyrene sulfonic acid resins.
[0018] In some possible implementations, in step S1, the weight ratio of organic solvent to water is 6:4-8:2; and / or the weight ratio of three organic solvents with boiling points of 70-100°C and organic solvent with boiling points of 100-120°C is 7:1-5:1; and / or the weight ratio of three organic solvents with boiling points of 70-100°C is 1:1:1-1:1.5:2.
[0019] In the above technical solution, controlling the weight ratio of various organic solvents within the above range can further improve the uniformity of the catalyst layer pore structure.
[0020] In some possible implementations, the catalyst content in the catalyst slurry is 4-20 wt%, and the ionomer resin content is 1-10 wt%.
[0021] In a second aspect, this application provides a fuel cell catalyst layer prepared according to the method for preparing the fuel cell catalyst layer in the above embodiments.
[0022] In the above technical solution, the pore structure of the fuel cell catalyst layer of this application is more uniform and fine, which can improve the durability of the support and long-term electrochemical stability when applied to PEMFC. Attached Figure Description
[0023] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0024] Figure 1 This is a SEM image of the catalyst layer prepared in Example 1 of this application; Figure 2 Here is a SEM image of the catalyst layer prepared in Comparative Example 1 of this application; Figure 3 This is a SEM image of the catalyst layer prepared in Comparative Example 2 of this application. Detailed Implementation
[0025] The embodiments of this application will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of this application. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.
[0026] The inventors of this application have discovered that when preparing a PEMFC catalyst layer using a catalyst slurry containing organic solvents with different boiling points, if the boiling points of the different organic solvents differ too little, they will evaporate rapidly together during drying, easily forming large pores in the catalyst layer, resulting in uneven pore size. Conversely, if the boiling points of the different organic solvents differ too much, the boiling points of the organic solvents in the catalyst slurry will be too low or too high, causing them to evaporate rapidly or be difficult to evaporate at low temperatures. Both of these factors contribute to uneven pore size in the prepared catalyst layer. Consequently, the resulting membrane electrode is more prone to water flooding during operation, leading to decreased support durability and electrochemical stability.
[0027] Based on this, this application provides a method for preparing a catalyst layer for a fuel cell, which includes the following steps: S1. Preparation of catalyst slurry The catalyst, solvent, and ionomer resin are mixed to form a catalyst slurry.
[0028] The solvents include organic solvents and water. The organic solvents include three organic solvents with boiling points of 70-100℃ and an organic solvent with boiling points of 100-120℃. Among the three organic solvents with boiling points of 70-100℃, the boiling point difference between any two adjacent organic solvents is in the range of 7-15℃.
[0029] As an example, three organic solvents with boiling points between 70 and 100°C are specified as solvent A, solvent B, and solvent C, with the boiling points of solvent A, solvent B, and solvent C increasing sequentially. The difference between the boiling points of solvent A and solvent B, or solvent B and solvent C, can be any value among 8°C, 9°C, 10°C, 11°C, 12°C, 13°C, and 14°C, or between any two values.
[0030] Specifically, the organic solvent with a boiling point of 70-100°C is selected from at least one of ethanol, n-propanol, isopropanol, sec-butanol, tert-butanol, n-propyl ether, methyl n-butyl ether, butanone, ethyl acetate, ethylene glycol dimethyl ether, trifluoroacetic acid, tetrahydropyran, propionitrile, acetonitrile, ethyl tert-butyl ether, 1,3-dioxolane, methyl isopropyl ketone, and 2,3-butanedione; the organic solvent with a boiling point of 100-120°C is selected from at least one of n-butanol, isobutanol, 3-pentanol, and neopentanol.
[0031] The weight ratio of organic solvent to water is 6:4-8:2; the weight ratio of the three organic solvents with boiling points of 70-100℃ and the organic solvent with boiling points of 100-120℃ is 7:1-5:1; and the weight ratio of the three organic solvents with boiling points of 70-100℃ is 1:1:1-1:1.5:2.
[0032] The catalyst can be at least one of a platinum-carbon catalyst and a platinum alloy catalyst. The platinum alloy catalyst can be a platinum-cobalt alloy or a platinum-nickel alloy supported on a carbon support, etc. All of the above catalysts are conventional hydroxide or oxygen reduction catalysts in the art, and will not be described in detail here.
[0033] Ionomer resins can act as proton conductors and binders in the catalyst layer. Specifically, they can be any one or more of perfluorosulfonic acid resins, partially fluorinated sulfonic acid resins, polyether ether ketone sulfonic acid resins, and polystyrene sulfonic acid resins.
[0034] In the catalyst slurry, the catalyst content is 4-20 wt%, and the ionomer resin content is 1-10 wt%.
[0035] As an example, the catalyst content can be any value of 6wt%, 8wt%, 10wt%, 12wt%, 14wt%, 16wt%, and 18wt%, or between any two values, and the ionomer resin content can be any value of 3wt%, 5wt%, 7wt%, and 9wt%, or between any two values.
[0036] Preferably, among the three organic solvents with boiling points of 70-100℃, the boiling point difference between any two adjacent organic solvents is within the range of 9-15℃. By controlling the boiling point difference within the above range, the uniformity and fineness of the prepared catalyst layer can be further improved.
[0037] Preferably, the boiling point of the organic solvent with a boiling point of 100-120℃ differs from that of water by more than 7℃.
[0038] Optionally, the mixing method can be ball milling, ultrasonic dispersion, mechanical stirring, etc.
[0039] S2, Preparation of the catalyst layer The catalyst slurry prepared above is applied to the base membrane and then sent to a drying device for drying to form a catalyst layer.
[0040] The drying equipment includes multiple oven sections, the number of which corresponds to the types of organic solvents and water. For example, if the catalyst slurry contains five types of organic solvents and water, then the oven will have five sections. During the drying process, the highest temperature of the oven is 20-30°C lower than the boiling point of the organic solvents (boiling point 100-120°C). The temperature of each section of the oven increases sequentially, with a temperature difference of 4-9°C between adjacent sections. The sequential temperature increase in the multiple oven sections refers to the temperature of each section increasing sequentially from the inlet to the outlet of the base film.
[0041] As an example, the highest temperature of the oven is lower than the boiling point of the organic solvent with a boiling point of 100-120°C by any one of the following values, or between any two values: 21°C, 22°C, 23°C, 24°C, 25°C, 26°C, 27°C, 28°C, and 29°C. The temperature difference between two adjacent oven sections is 5°C, 6°C, 7°C, and 8°C, or between any two values.
[0042] The base membrane, which serves as the carrier of the catalyst layer, can be a proton exchange membrane or a transfer membrane. If a transfer membrane is used, the prepared catalyst layer needs to be transferred onto the proton exchange membrane in the subsequent process.
[0043] During the drying process, the base film dries for 20-60 seconds in each section of the oven. The drying time of the base film in the oven can be controlled by adjusting the transport speed of the base film or the length of the oven.
[0044] As an example, the base film is dried in each oven for any of the following values: 25s, 30s, 35s, 40s, 45s, 50s, and 55s, or between any two of these values.
[0045] Preferably, the highest temperature of the drying oven during the drying process is 24-28°C lower than the boiling point of the organic solvent with a boiling point of 100-120°C, and the temperature difference between two adjacent sections of the drying oven is 5-7°C.
[0046] Alternatively, the catalyst slurry can be applied to the base film by coating with a coating machine or by spraying.
[0047] The method for preparing the fuel cell catalyst layer of this application utilizes a variety of organic solvents with different boiling points to prepare catalyst slurry. The boiling point difference of each organic solvent is controlled within a suitable range, and the temperature of each section of the drying oven is controlled within a suitable range during the drying process. This allows the solvents with different boiling points to evaporate in a gradient during coating and drying, avoiding the problem of a large amount of solvent evaporating in a short time and forming large pores. The catalyst layer has a more uniform and fine pore structure, which effectively improves the durability of the membrane electrode support and the long-term electrochemical stability.
[0048] This application also provides a fuel cell catalyst layer, which is prepared according to the method for preparing the fuel cell catalyst layer in the above embodiments. The catalyst layer can be used as a cathode catalyst layer or an anode catalyst layer of a fuel cell, preferably as a cathode catalyst layer.
[0049] The following describes in further detail a fuel cell catalyst layer and its preparation method according to the present application, with reference to the embodiments. Example 1
[0050] This application provides a fuel cell catalyst layer and its preparation method, which includes the following steps: S1. Preparation of catalyst slurry Add 300g of grinding beads, 15g of 60wt% Pt / C catalyst, 6g of D2020 perfluorosulfonic acid resin, 83.7g of water, 41.85g of ethanol (boiling point 78.2℃), 55.8g of tetrahydropyran (boiling point 88℃), 69.75g of n-propanol (boiling point 97.4℃), and 27.9g of isobutanol (boiling point 108℃) to a 1L ball mill jar. Mill the mixture at 250rpm for 24h using a planetary ball mill. After degassing, obtain the catalyst slurry.
[0051] S2, Preparation of the catalyst layer The catalyst slurry is coated onto the proton exchange membrane using a coating machine, and then sent to a drying device for drying. The drying device consists of five ovens 1-5 in sequence. The temperature of oven 1 is set to 60℃, oven 2 to 65℃, oven 3 to 70℃, oven 4 to 75℃, and oven 5 to 80℃. The proton exchange membrane coated with the catalyst slurry enters from oven 1 and exits from oven 5. The drying time in each oven is 40 seconds. After drying, a catalyst layer supported on the proton exchange membrane is obtained. Example 2
[0052] This application provides a fuel cell catalyst layer and its preparation method, which includes the following steps: S1. Preparation of catalyst slurry Add 300g of grinding beads, 15g of 60wt% Pt / C catalyst, 6g of D2020 perfluorosulfonic acid resin, 83.7g of water, 41.85g of ethyl tert-butyl ether (boiling point 72.8℃), 55.8g of isopropanol (boiling point 82.6℃), 69.75g of n-propanol (boiling point 97.4℃), and 27.9g of isobutanol (boiling point 108℃) to a 1L ball mill jar. Mill the mixture at 250rpm for 24h using a planetary ball mill. After degassing, obtain the catalyst slurry.
[0053] S2, Preparation of the catalyst layer The catalyst slurry is coated onto the proton exchange membrane using a coating machine, and then sent to a drying device for drying. The drying device consists of five ovens 1-5 in sequence. The temperature of oven 1 is set to 60℃, oven 2 to 65℃, oven 3 to 70℃, oven 4 to 75℃, and oven 5 to 80℃. The proton exchange membrane coated with the catalyst slurry enters from oven 1 and exits from oven 5. The drying time in each oven is 40 seconds. After drying, a catalyst layer supported on the proton exchange membrane is obtained. Example 3
[0054] This application provides a fuel cell catalyst layer and its preparation method, which includes the following steps: S1. Preparation of catalyst slurry Add 300g of grinding beads, 15g of 60wt% Pt / C catalyst, 6g of D2020 perfluorosulfonic acid resin, 83.7g of water, 41.85g of ethanol (boiling point 78.2℃), 55.8g of tetrahydropyran (boiling point 88℃), 69.75g of n-propanol (boiling point 97.4℃), and 27.9g of isobutanol (boiling point 108℃) to a 1L ball mill jar. Mill the mixture at 250rpm for 24h using a planetary ball mill. After degassing, obtain the catalyst slurry.
[0055] S2, Preparation of the catalyst layer The catalyst slurry is coated onto the proton exchange membrane using a coating machine, and then sent to a drying device for drying. The drying device consists of five ovens 1-5. The temperature of oven 1 is set to 65℃, oven 2 to 70℃, oven 3 to 75℃, oven 4 to 80℃, and oven 5 to 85℃. The proton exchange membrane coated with the catalyst slurry enters from oven 1 and exits from oven 5. The drying time in each oven is 40 seconds. After drying, a catalyst layer supported on the proton exchange membrane is obtained. Example 4
[0056] This application provides a fuel cell catalyst layer and its preparation method, which includes the following steps: S1. Preparation of catalyst slurry Add 300g of grinding beads, 15g of 60wt% Pt / C catalyst, 6g of D2020 perfluorosulfonic acid resin, 83.7g of water, 41.85g of ethanol (boiling point 78.2℃), 55.8g of tetrahydropyran (boiling point 88℃), 69.75g of n-propanol (boiling point 97.4℃), and 27.9g of neopentyl alcohol (boiling point 113.1℃) to a 1L ball mill jar. Mill the mixture at 250rpm for 24h using a planetary ball mill. After degassing, obtain the catalyst slurry.
[0057] S2, Preparation of the catalyst layer The catalyst slurry is coated onto the proton exchange membrane using a coating machine, and then sent to a drying device for drying. The drying device consists of five ovens 1-5. The temperature of oven 1 is set to 65℃, oven 2 to 70℃, oven 3 to 75℃, oven 4 to 80℃, and oven 5 to 85℃. The proton exchange membrane coated with the catalyst slurry enters from oven 1 and exits from oven 5. The drying time in each oven is 40 seconds. After drying, a catalyst layer supported on the proton exchange membrane is obtained. Example 5
[0058] This application provides a fuel cell catalyst layer and its preparation method, which includes the following steps: S1. Preparation of catalyst slurry Add 300g of grinding beads, 20g of 60wt% Pt / C catalyst, 8g of D2020 perfluorosulfonic acid resin, 83.7g of water, 55.8g of ethanol (boiling point 78.2℃), 55.8g of tetrahydropyran (boiling point 88℃), 55.8g of n-propanol (boiling point 97.4℃), and 24.8g of isobutanol (boiling point 108℃) to a 1L ball mill jar. Mill the mixture at 250rpm for 24h using a planetary ball mill. After degassing, obtain the catalyst slurry.
[0059] S2, Preparation of the catalyst layer The catalyst slurry is coated onto the proton exchange membrane using a coating machine, and then sent to a drying device for drying. The drying device consists of five ovens 1-5 in sequence. The temperature of oven 1 is set to 60℃, oven 2 to 65℃, oven 3 to 72℃, oven 4 to 78℃, and oven 5 to 85℃. The proton exchange membrane coated with the catalyst slurry enters from oven 1 and exits from oven 5. The drying time in each oven is 60 seconds. After drying, a catalyst layer supported on the proton exchange membrane is obtained. Comparative Example 1
[0060] This application provides a fuel cell catalyst layer and its preparation method, which includes the following steps: S1. Preparation of catalyst slurry Add 300g of grinding beads, 15g of 60wt% Pt / C catalyst, 6g of D2020 perfluorosulfonic acid resin, 83.7g of water, 41.85g of ethanol (boiling point 78.2℃), 55.8g of isopropanol (boiling point 82.6℃), 69.75g of n-propanol (boiling point 97.4℃), and 27.9g of isobutanol (boiling point 108℃) to a 1L ball mill jar. Mill the mixture at 250rpm for 24h using a planetary ball mill. After degassing, obtain the catalyst slurry.
[0061] S2, Preparation of the catalyst layer The catalyst slurry is coated onto the proton exchange membrane using a coating machine, and then sent to a drying device for drying. The drying device consists of five ovens 1-5 in sequence. The temperature of oven 1 is set to 60℃, oven 2 to 65℃, oven 3 to 70℃, oven 4 to 75℃, and oven 5 to 80℃. The proton exchange membrane coated with the catalyst slurry enters from oven 1 and exits from oven 5. The drying time in each oven is 40 seconds. After drying, a catalyst layer supported on the proton exchange membrane is obtained. Comparative Example 2
[0062] This application provides a fuel cell catalyst layer and its preparation method, which includes the following steps: S1. Preparation of catalyst slurry Add 300g of grinding beads, 15g of 60wt% Pt / C catalyst, 6g of D2020 perfluorosulfonic acid resin, 83.7g of water, 41.85g of methanol (boiling point 64.7℃), 55.8g of isopropanol (boiling point 82.6℃), 69.75g of n-propanol (boiling point 97.4℃), and 27.9g of isobutanol (boiling point 108℃) to a 1L ball mill jar. Mill the mixture at 250rpm for 24h using a planetary ball mill. After degassing, obtain the catalyst slurry.
[0063] S2, Preparation of the catalyst layer The catalyst slurry is coated onto the proton exchange membrane using a coating machine, and then sent to a drying device for drying. The drying device consists of five ovens 1-5 in sequence. The temperature of oven 1 is set to 60℃, oven 2 to 65℃, oven 3 to 70℃, oven 4 to 75℃, and oven 5 to 80℃. The proton exchange membrane coated with the catalyst slurry enters from oven 1 and exits from oven 5. The drying time in each oven is 40 seconds. After drying, a catalyst layer supported on the proton exchange membrane is obtained. Comparative Example 3
[0064] S1. Preparation of catalyst slurry Add 300g of grinding beads, 15g of 60wt% Pt / C catalyst, 6g of D2020 perfluorosulfonic acid resin, 83.7g of water, 41.85g of ethanol (boiling point 78.2℃), 55.8g of isopropanol (boiling point 82.6℃), 69.75g of n-propanol (boiling point 97.4℃), and 27.9g of isobutanol (boiling point 108℃) to a 1L ball mill jar. Mill the mixture at 250rpm for 24h using a planetary ball mill. After degassing, obtain the catalyst slurry.
[0065] S2, Preparation of the catalyst layer The catalyst slurry is coated onto the proton exchange membrane using a coating machine, and then sent to a drying device for drying. The drying device consists of five ovens 1-5 in sequence. The temperature of oven 1 is set to 70℃, the temperature of oven 2 is set to 70℃, the temperature of oven 3 is set to 70℃, the temperature of oven 4 is set to 70℃, and the temperature of oven 5 is set to 70℃. The proton exchange membrane coated with the catalyst slurry enters from oven 1 and exits from oven 5. The drying time in each oven is 40 seconds. After drying, a catalyst layer supported on the proton exchange membrane is obtained. Experimental Example 1
[0066] SEM images of the surfaces of the catalyst layers prepared in Example 1 and Comparative Examples 1-2 were obtained, as shown below. Figures 1-3 As shown.
[0067] Depend on Figure 1-3 It can be seen that in Example 1, the boiling point difference of each organic solvent in the catalyst slurry was controlled within a suitable range, resulting in a catalyst layer with uniform and fine pores. However, in Comparative Examples 1-2, the boiling point difference of the organic solvents in the catalyst slurry was too large or too small, resulting in catalyst layers with larger pores and uneven pore size. Experimental Example 2
[0068] The durability of the membrane electrode carriers for the catalytic layers prepared in Examples 1-5 and Comparative Examples 1-3 as cathode catalytic layers was tested respectively, and the test results are shown in Table 1.
[0069] The testing method is as follows: Preparation of CCM (Catalyst Coated Membrane): 10g of 50wt% Pt / C catalyst and 5g of D2020 perfluorosulfonic acid resin were dispersed in a mixture of 150g water and 150g ethanol using ultrasonic dispersion to obtain an anode catalyst slurry. The anode catalyst slurry was then coated onto the other side of the proton exchange membranes coated with the cathode catalyst layer prepared in Examples 1-5 and Comparative Examples 1-3 using a coating machine, and dried in an oven at 60°C.
[0070] The prepared CCM, cathode carbon paper, and anode carbon paper were used to assemble a membrane electrode and the following tests were performed using a test fixture.
[0071] Polarization curve test: The fuel cell test temperature was set to 75℃, hydrogen was passed through the anode and air was passed through the cathode, the gas metering ratio of the anode to the cathode was 1.5:2, the humidity of the anode was 30%, the humidity of the cathode was 30%, the back pressure of the anode and cathode was 150kPa, and the initial voltage value under a current density of 1.5A was recorded.
[0072] Accelerated durability test of the fuel cell: The test temperature of the fuel cell was set to 80℃, hydrogen was introduced through the anode and nitrogen through the cathode, the gas metering ratio of the anode to the cathode was 1.5:2, the humidity of the anode was 100%, the humidity of the cathode was 100%, there was no back pressure at the anode and cathode, a 1-1.5V triangular wave was circulated for 1000 cycles, with one cycle lasting 2 seconds, and then the polarization curve test was performed. The voltage value after durability test was recorded at a current density of 1.5A.
[0073] Table 1 Test Results <![CDATA[Initial voltage value V@1.5A / cm 2 > <![CDATA[Voltage value V @ 1.5 A / cm after 1000 - cycle 2 > Carrier durability voltage decay mV Example 1 0.721 0.702 19 Example 2 0.722 0.702 20 Example 3 0.721 0.700 21 Example 4 0.719 0.699 20 Example 5 0.720 0.697 23 Comparative Example 1 0.719 0.686 33 Comparative Example 2 0.717 0.679 38 Comparative Example 3 0.717 0.682 35
[0074] As shown in Table 1, the carrier durability voltage decay of Examples 1-5 is less than that of Comparative Examples 1-3, indicating that the carrier durability of the catalyst layers prepared in Examples 1-5 is better than that of the carriers prepared in Comparative Examples 1-3.
[0075] The above description is merely a specific embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.
Claims
1. A method for preparing a catalyst layer for a fuel cell, characterized in that, The preparation method includes the following steps: S1. A catalyst slurry is formed by mixing a catalyst, a solvent, and an ionomer resin. The solvent includes an organic solvent and water. The organic solvent includes three organic solvents with boiling points of 70-100°C and an organic solvent with boiling points of 100-120°C. The boiling point difference between any two adjacent organic solvents with boiling points of 70-100°C is in the range of 7-15°C. S2. The catalyst slurry is applied to the base film and then sent to a drying device for drying to form a catalyst layer; wherein, the drying device includes multiple ovens, the number of ovens being the same as the types of organic solvent and water, and the highest temperature of the ovens during the drying process being 20-30°C lower than the boiling point of the organic solvent which has a boiling point of 100-120°C, the temperature of the multiple ovens increasing sequentially, and the temperature difference between two adjacent ovens being 4-9°C.
2. The method for preparing the fuel cell catalyst layer according to claim 1, characterized in that, In step S1, the boiling point difference between any two adjacent organic solvents among the three organic solvents with boiling points of 70-100°C ranges from 9-15°C.
3. The method for preparing the fuel cell catalyst layer according to claim 1, characterized in that, In step S1, the boiling point of the organic solvent, which has a boiling point of 100-120°C, differs from that of water by more than 7°C.
4. The method for preparing the catalyst layer of a fuel cell according to claim 1, characterized in that, In step S2, the highest temperature of the oven during the drying process is 24-28°C lower than the boiling point of the organic solvent, which has a boiling point of 100-120°C, and the temperature difference between two adjacent sections of the oven is 5-7°C; and / or In step S2, the base membrane is a proton exchange membrane or a transfer membrane; and / or In step S2, the base film is dried for 20-60 seconds in each section of the oven during the drying process.
5. The method for preparing the fuel cell catalyst layer according to claim 1, characterized in that, The organic solvent with a boiling point of 70-100°C is selected from at least one of ethanol, n-propanol, isopropanol, sec-butanol, tert-butanol, n-propyl ether, methyl n-butyl ether, butanone, ethyl acetate, ethylene glycol dimethyl ether, trifluoroacetic acid, tetrahydropyran, propionitrile, acetonitrile, ethyl tert-butyl ether, 1,3-dioxolane, methyl isopropyl ketone, and 2,3-butanedione; and / or The organic solvent with a boiling point of 100-120°C is selected from at least one of n-butanol, isobutanol, 3-pentanol, and neopentanol.
6. The method for preparing the catalyst layer of a fuel cell according to claim 1, characterized in that, The catalyst is selected from at least one of platinum-carbon catalysts and platinum alloy catalysts.
7. The method for preparing the catalyst layer of a fuel cell according to claim 1, characterized in that, The ionomer resin is selected from any one or more of perfluorosulfonic acid resins, partially fluorinated sulfonic acid resins, polyetheretherketone sulfonic acid resins, and polystyrene sulfonic acid resins.
8. The method for preparing the catalyst layer of a fuel cell according to claim 1, characterized in that, In step S1, the weight ratio of the organic solvent to water is 6:4-8:2; and / or The weight ratio of three organic solvents with boiling points of 70-100℃ to an organic solvent with a boiling point of 100-120℃ is 7:1-5:1; and / or The weight ratio of the three organic solvents with boiling points between 70 and 100°C is 1:1:1 to 1:1.5:
2.
9. The method for preparing the catalyst layer of a fuel cell according to claim 1, characterized in that, In the catalyst slurry, the content of the catalyst is 4-20 wt%, and the content of the ionomer resin is 1-10 wt%.
10. A catalyst layer for a fuel cell, characterized in that, The fuel cell catalyst layer is prepared by the method for preparing the fuel cell catalyst layer according to any one of claims 1 to 9.