Catalytic layer for fuel cell, preparation method of catalytic layer, membrane electrode and fuel cell

Abstract

The invention provides a catalyst layer for a fuel cell, a preparation method of the catalyst layer, a membrane electrode and the fuel cell, and the preparation method of the catalyst layer comprises the following steps: firstly, uniformly mixing a first catalyst, a second catalyst, a Nafion resin solution and a water-alcohol solution to obtain catalyst slurry; secondly, coating one side of the proton exchange membrane with the catalyst slurry, drying the proton exchange membrane at normal temperature, and drying the proton exchange membrane in a drying tunnel to form a first catalyst layer in the catalyst layers; and finally, repeating the step S20 on the other side of the proton exchange membrane to form a second catalyst layer in the catalyst layers, the catalyst layer prepared by the method is coated with the Pt / C catalyst slurry containing two different loading capacities and particle sizes and dried at normal temperature, so that the prepared catalyst layer has gradient pore size distribution and gradient Pt loading capacity distribution at the same time, the mass transfer performance of the catalyst layer is improved, the Pt utilization rate is increased, and finally the electrical performance of the fuel cell is improved.

Description

Technical Field

[0001] This invention relates to the field of proton exchange membrane fuel cell technology, and particularly to a catalyst proton membrane coating and its preparation method, as well as a membrane electrode and a fuel cell. Background Technology

[0002] A proton exchange membrane fuel cell (PEMFC) is an energy conversion device that directly converts the chemical energy of 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.

[0003] The membrane electrode assembly (MEA) is a core component of a fuel cell, providing a reaction site for the reactants and converting chemical energy into electrical energy. It serves as the site for multiphase mass transport and electrochemical reactions. The performance and durability of the MEA directly determine the power generation efficiency and lifespan of the fuel cell. The catalyst layer, as one of the core components of the MEA, directly affects the overall efficiency and lifespan of the fuel cell. Traditional catalyst layer preparation methods often use catalyst slurries with a single particle size and Pt content for coating, resulting in limitations in mass transfer capacity and Pt utilization.

[0004] Therefore, there is an urgent need for a catalyst layer for fuel cells and its preparation method, as well as membrane electrode assembly and fuel cell, to solve the above-mentioned technical problems. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned technical deficiencies and to propose a catalyst layer for fuel cells and its preparation method, as well as a membrane electrode and a fuel cell, thereby solving the technical problems of poor mass transfer capacity and low Pt utilization in the catalyst layer of existing fuel cells.

[0006] To address the aforementioned technical problems, the present invention first provides a method for preparing a catalyst layer for a fuel cell, comprising: S10, the first catalyst, the second catalyst, the Nafion resin solution and the aqueous alcohol solution are mixed evenly to obtain a catalyst slurry; S20: The catalyst slurry is coated on one side of the proton exchange membrane, dried at room temperature, and then dried in an oven to form the first catalyst layer in the catalyst layer. S30, repeat step S20 on the other side of the proton exchange membrane to form the second catalyst layer in the catalyst layer; In step S10, both the first catalyst and the second catalyst are Pt / C catalysts, and the particle size of the first catalyst is smaller than that of the second catalyst, while the Pt content of the first catalyst is greater than that of the second catalyst.

[0007] Preferably, in step S10, the particle size of both the first catalyst and the second catalyst is 10-100 nm, and the Pt content of both the first catalyst and the second catalyst is 10%-90%.

[0008] Preferably, in step S10, the sum of the masses of the first catalyst and the second catalyst accounts for 5% to 10% of the total mass of the catalyst slurry.

[0009] Preferably, in step S20, the drying time for room temperature drying is 30–180 min, the temperature for drying in the drying tunnel is 40–120 °C, and the drying time is 2–60 min.

[0010] Preferably, after step S20 is completed and before step S30 is performed, the process further includes: forming a release membrane on the first catalyst layer and peeling off the proton exchange membrane substrate located on the other side of the proton exchange membrane.

[0011] Preferably, the release film includes any one of PET, PEN, PEI, PPS, PSU and PPSU, and the temperature resistance range of the release film is 25 to 150°C.

[0012] Preferably, the pore sizes of both the first and second catalyst layers increase from the inside to the outside of the proton exchange membrane, and the Pt loading of both the first and second catalyst layers decreases from the inside to the outside of the proton exchange membrane.

[0013] Accordingly, the present invention also provides a catalyst layer for a fuel cell, which is prepared by the method for preparing a catalyst layer for a fuel cell as described in any of the above claims; The pore sizes of both the first and second catalyst layers are 1 nm to 100 μm; the Pt loading of both the first and second catalyst layers is 0.05 to 1 mg•Pt / cm³. 2 .

[0014] Accordingly, the present invention also provides a membrane electrode assembly, comprising the above-described catalyst layer, proton exchange membrane, border membrane, and gas diffusion layer, wherein the border membrane is respectively attached to the first catalyst layer, the second catalyst layer, and the proton exchange membrane, and the gas diffusion layer is attached to the border membrane. Accordingly, the present invention also provides a fuel cell, comprising the above-described membrane electrode assembly.

[0015] The beneficial effects of this invention are as follows: Unlike existing technologies, this invention provides a catalyst layer for fuel cells, its preparation method, a membrane electrode assembly (MEA), and a fuel cell. The catalyst layer preparation method involves mixing two Pt / C catalysts with different particle sizes and Pt contents to prepare a catalyst slurry. The small-particle-size, high-Pt-content particles have high surface energy, strong interaction with the proton exchange membrane and Nafion resin solution, and are more easily carried by solvent convection during drying. Meanwhile, the large-particle-size, low-Pt-content particles, due to their strong sedimentation driving force and low diffusion coefficient, deposit first. This achieves a vertical rearrangement of the catalyst particles, forming a gradient distribution of a first or second catalyst layer with increasing pore size and decreasing Pt loading from the inside out. This gradient structure shortens the mass transfer path for reactants (such as hydrogen and oxygen) to reach highly active sites (high Pt content regions). The large-pore region reduces gas diffusion resistance and improves mass transfer efficiency. Simultaneously, the high-Pt-content inner layer directly contacts the proton exchange membrane, reducing proton transport losses and improving the utilization rate of Pt's catalytic activity. Furthermore, this preparation method can flexibly change the gradient structure by simply adjusting the catalyst slurry ratio and coating parameters, which has good process controllability and repeatability and is easy to industrialize. The membrane electrode and fuel cell prepared in this way achieve higher power generation efficiency and longer service life due to the dual improvement of mass transfer and catalytic performance of the catalyst layer, and can be widely used in the field of hydrogen energy. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating a method for preparing a catalyst layer for a fuel cell, as provided in an embodiment of the present invention. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0018] To address the problems existing in the prior art, this invention proposes a novel catalyst layer for fuel cells and its preparation method, as well as a membrane electrode assembly and fuel cell using the catalyst layer, solving problems such as poor mass transfer capacity and low Pt utilization.

[0019] The objective of this invention is achieved through the following technical solution: Please see Figure 1 , Figure 1 This is a flowchart illustrating a method for preparing a catalyst layer for a fuel cell according to an embodiment of the present invention; the method for preparing a catalyst layer for a fuel cell according to the present invention includes: S10, the first catalyst, the second catalyst, the Nafion resin solution and the aqueous alcohol solution are mixed evenly to obtain a catalyst slurry.

[0020] Specifically, S10 also includes: First, a first catalyst and a second catalyst are provided. Both the first catalyst and the second catalyst are Pt / C catalysts, and the particle size of the first catalyst is smaller than that of the second catalyst, while the Pt content of the first catalyst is greater than that of the second catalyst.

[0021] Next, the first catalyst, the second catalyst, the Nafion resin solution (a functional colloidal solution with perfluorosulfonic acid resin as solute and alcohol-water mixture as solvent) and the water-alcohol solution are mixed evenly to obtain the catalyst slurry.

[0022] In step S10, the first catalyst, with its small particle size and high Pt content, possesses a larger specific surface area and stronger catalytic activity, while the second catalyst, with its large particle size and low Pt content, helps to construct a pore structure more conducive to gas diffusion. These two catalysts are then mixed with Nafion resin solution and a water-alcohol solution. The Nafion resin solution effectively disperses the catalyst particles and enhances proton conductivity, while the water-alcohol solution provides a suitable solvent environment to ensure uniform mixing. This specific selection of raw materials and mixing method lays the foundation for the vertical rearrangement of catalyst particles during the subsequent drying process, forming a catalyst layer with a gradient pore size distribution and gradient Pt loading. This allows the catalyst layer to exert highly efficient catalytic activity at highly active sites while also possessing good mass transfer channels, thereby significantly improving the overall performance and Pt utilization rate of the fuel cell.

[0023] Specifically, the particle size of both the first and second catalysts is 10–100 nm, and the Pt content of both catalysts is 10%–90%. This particle size range ensures that the catalysts have a high specific surface area to expose sufficient active sites, while the Pt content range takes into account both catalytic activity and cost control. Through the synergistic regulation of the two, an optimized structure of "dense high-activity sites in the inner layer and unobstructed mass transfer channels in the outer layer" can be formed during the drying and rearrangement of the catalyst layer, which significantly improves the reaction kinetics performance and precious metal utilization efficiency of the fuel cell.

[0024] Specifically, the combined mass of the first and second catalysts accounts for 5% to 10% of the total mass of the catalyst slurry. This ratio range ensures that the catalyst slurry has suitable solid content and rheological properties: too low a catalyst ratio can lead to insufficient catalyst layer thickness and low active site density, while too high a ratio may cause a decrease in coating uniformity due to a surge in viscosity. This mass ratio range not only allows for the formation of a stable dispersion system through the Nafion resin solution and the aqueous alcohol solvent, preventing catalyst particle agglomeration, but also provides sufficient migration space for the vertical rearrangement of particles during the drying process, ensuring the orderly construction of the gradient structure of the catalyst layer.

[0025] S20 involves coating the catalyst slurry onto one side of the proton exchange membrane, drying it at room temperature, and then drying it in an oven tunnel to form the first catalyst layer in the catalyst layer.

[0026] Specifically, step S20 also includes: The catalyst slurry is coated onto one side of the proton exchange membrane, dried at room temperature, and then dried in an oven to form the first catalyst layer. During the coating process, the thickness and uniformity of the first catalyst layer can be controlled by adjusting parameters such as coating speed and coating amount. After coating, it is dried at room temperature to allow the solvent in the catalyst slurry to evaporate, and the catalyst particles form a preliminary first catalyst layer structure on the surface of the proton exchange membrane. The temperature and time of the room temperature drying process can be adjusted according to actual needs.

[0027] Specifically, the drying time at room temperature is 30–180 min, the drying temperature in the drying tunnel is 40–120℃, and the drying time is 2–60 min. By precisely controlling the coating speed and amount, the uniformity of the catalyst layer thickness and areal density can be accurately controlled. Combined with the 30–180 min room temperature drying process to induce solvent gradient evaporation, the catalyst particles are initially rearranged to form a three-dimensional framework. Then, the catalyst is cured by gradient heating in the drying tunnel at 40–120℃, simultaneously achieving the melting and recrystallization of Nafion ionomers and optimizing the porosity of the catalyst layer. This process, through multi-stage drying kinetic control, ensures the uniformity of the catalyst layer thickness while constructing a proton conduction network with a reasonable pore size distribution. This avoids the decrease in ion conductivity caused by solvent residue and enhances the catalyst-ionomer interface bonding force through temperature program control. Ultimately, this reduces the mass transfer resistance of the catalyst layer and improves the exposure efficiency of Pt active sites, ensuring high performance of the membrane electrode and process repeatability.

[0028] S30, repeat step S20 on the other side of the proton exchange membrane to form the second catalyst layer in the catalyst layer.

[0029] Specifically, step S30 also includes: First, a release film is formed on the first catalyst layer, and the proton exchange membrane substrate located on the other side of the proton exchange membrane is peeled off. Then, another portion of catalyst slurry is coated on the other side of the proton exchange membrane, dried at room temperature, and then dried in an oven to form the second catalyst layer in the catalyst layer.

[0030] Specifically, by forming a temporary support barrier by composite release film on the surface of the first catalyst layer, mechanical stress can be effectively isolated when peeling off the proton exchange membrane substrate on the other side of the proton exchange membrane, avoiding deformation or damage to the formed first catalyst layer caused by tearing of the proton exchange membrane substrate. The low surface energy of the release film can also suppress accidental adhesion between the first catalyst layer and the uncoated side of the proton exchange membrane, ensuring the cleanliness and integrity of the proton exchange membrane surface after the proton exchange membrane substrate is peeled off. Subsequently, utilizing the carrier function of the release film, a second catalyst slurry is precisely coated on the exposed side of the proton exchange membrane, and a symmetrical double-sided catalyst layer structure is formed through a gradient drying process. In this process, the release film not only maintains the microstructure stability of the first catalyst layer, but also achieves non-destructive bonding between the double catalyst layer and the proton exchange membrane through controllable peeling, ultimately constructing a membrane electrode with a bidirectional gradient distribution of pore size and Pt loading, significantly improving gas mass transfer uniformity and proton conduction efficiency, and providing process assurance for the synergistic optimization of fuel cell power density and cycle life.

[0031] Specifically, the release film includes any one of PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PEI (polyetherimide), PPS (polyphenylene sulfide), PSU (polysulfone), and PPSU (polyphenyl sulfone), and the temperature resistance range of the release film is 25-150℃. The above materials, with their excellent chemical inertness and surface release treatment, can provide a smooth and flat support substrate for the catalyst layer during the coating process to ensure thickness uniformity, and can achieve the non-destructive transfer of the first catalyst layer through controllable release force during peeling. The rigid skeleton of its molecular chain can also suppress the internal stress generated by solvent evaporation during the drying process, ensuring the integrity of the gradient structure of the catalyst layer. It is a key auxiliary material for constructing high-performance membrane electrodes.

[0032] Specifically, the pore sizes of both the first and second catalyst layers increase from the inside to the outside of the proton exchange membrane, while the Pt loading of both layers decreases from the inside to the outside. This gradient design of pore size and Pt loading synergistically optimizes the distribution of the three-phase interface (active sites-proton channels-gas channels) of the catalyst layer. It improves the catalytic efficiency per unit area through the high Pt loading in the inner layer and reduces mass transfer polarization through the large-pore network in the outer layer. This allows the fuel cell to maintain high Pt atom economy while simultaneously improving both the reactant gas diffusion rate and proton conduction efficiency, significantly enhancing power density and long-term operational stability.

[0033] Accordingly, the present invention also provides a catalyst layer prepared by any of the above-mentioned methods for preparing a catalyst layer for a fuel cell; The pore sizes of both the first and second catalyst layers are 1 nm to 100 μm; the Pt loading of both the first and second catalyst layers is 0.05 to 1 mg•Pt / cm³. 2 .

[0034] Specifically, the catalyst layer prepared in this invention constructs an optimized three-phase reaction interface by precisely controlling a gradient pore size of 1–100 μm and a gradient Pt loading of 0.05–1 mg Pt / cm²: the inner layer with small pore size (1–20 μm) and high Pt loading (0.5–1 mg Pt / cm²) shortens the proton conduction path and enhances catalytic activity; the outer layer with large pore size (20–100 μm) and low Pt loading (0.05–0.3 mg Pt / cm²) reduces gas diffusion resistance and enhances mass transfer efficiency. This gradient structure increases the Pt atom utilization rate to over 85%, reducing the amount of precious metals used by more than 30% compared to traditional homogeneous catalyst layers, achieving a synergistic breakthrough of low cost, high activity, and long lifespan, and can be widely adapted to fuel cell applications with different power density requirements.

[0035] Accordingly, the present invention also provides a membrane electrode, comprising the above-mentioned catalytic layer, proton membrane, border membrane and gas diffusion layer, wherein the border membrane is respectively attached to the first catalytic layer, the second catalytic layer and the proton membrane, and the gas diffusion layer is attached to the border membrane.

[0036] Accordingly, the present invention also provides a fuel cell, including the membrane electrode as described above.

[0037] The technical solution of the present invention will now be further described with reference to specific embodiments, wherein the proton exchange membranes used in Embodiment 1 and Comparative Examples 1-2 are of the same type.

[0038] Example 1: This embodiment 1 provides a catalyst layer for a fuel cell and its preparation method, as well as a membrane electrode and a fuel cell. The preparation method of the catalyst layer specifically includes: Step (1): Weigh 5g of Pt / C catalyst A (Pt content of 60%, particle size of 30nm) and 5g of Pt / C catalyst B (Pt content of 40%, particle size of 70nm), and mix Pt / C catalyst A, Pt / C catalyst B, Nafion resin solution and water-alcohol solution evenly, keeping the I / C ratio (mass ratio of ionomer to C, used to balance the conduction requirements of high Pt catalyst and the mass transfer requirements of large particle size catalyst) at 0.9, and fully shear and disperse to obtain catalyst slurry; Step (2): The catalyst slurry is coated onto the proton exchange membrane by slit extrusion to obtain the first catalyst layer; the coating speed is 1 m / min and the coating thickness is 100 µm; after coating, it is dried at room temperature for 120 min at 25 °C; then it is dried in an oven at 80 °C for 30 min. Step (3): Cover the first catalyst layer side of the proton exchange membrane after drying in step (2) with a release membrane and peel off the original bottom membrane of the proton exchange membrane. Then, apply the catalyst slurry onto the proton exchange membrane by slit extrusion to obtain the second catalyst layer. The coating speed is 1 m / min and the coating thickness is 30 µm. After coating, dry at room temperature (25 °C) for 60 min. Then, dry in an oven at 80 °C for 10 min. Finally, remove the release membrane to obtain a catalyst layer with gradient pore size distribution and gradient Pt loading distribution. The pore size of both the first and second catalyst layers is 1 nm to 100 µm, and the Pt loading of both the first and second catalyst layers is 0.445 mg•Pt / cm². 2 .

[0039] Furthermore, the first and second catalytic layers are respectively sealed with borders and carbon paper is attached to obtain the membrane electrode.

[0040] Comparative Example 1: Comparative Example 1 provides a catalyst layer for a fuel cell and its preparation method, as well as a membrane electrode assembly and a fuel cell. The preparation method of the catalyst layer specifically includes: Step (1): Weigh 10g of Pt / C catalyst A (Pt content is 60%, particle size is 30nm), and mix 10g of Pt / C catalyst A, Nafion resin solution and water-alcohol solution evenly, keeping the I / C ratio at 0.9, and fully shear and disperse to obtain catalyst slurry; Step (2): The catalyst slurry is coated onto the proton exchange membrane by slit extrusion to obtain the first catalyst layer; the coating speed is 1 m / min and the coating thickness is 100 µm; after coating, it is dried at room temperature for 120 min at 25 °C; then it is dried in an oven at 80 °C for 30 min. Step (3): Cover the first catalyst layer side of the proton exchange membrane after drying in step (2) with a release membrane and peel off the original bottom membrane of the proton exchange membrane. Then, apply the catalyst slurry onto the proton exchange membrane by slit extrusion to obtain the second catalyst layer. The coating speed is 1 m / min and the coating thickness is 30 µm. After coating, dry at room temperature (25 °C) for 60 min. Then, dry in an oven at 80 °C for 10 min. Finally, remove the release membrane to obtain a catalyst layer with conventional pore size distribution and conventional Pt loading distribution. At this time, the catalyst layer prepared in Comparative Example 1 does not have gradient pore size distribution and gradient Pt loading distribution, and the Pt loading of both the first and second catalyst layers prepared in Comparative Example 1 is 0.458 mg•Pt / cm. 2 . Furthermore, the first and second catalytic layers are respectively sealed with borders and carbon paper is attached to obtain the membrane electrode.

[0041] Comparative Example 2: Comparative Example 2 provides a catalyst layer for a fuel cell and its preparation method, as well as a membrane electrode assembly and a fuel cell. The preparation method of the catalyst layer specifically includes: Step (1): Weigh 10g of Pt / C catalyst B (Pt content is 40%, particle size is 70nm), and mix 10g of Pt / C catalyst B, Nafion resin solution and water-alcohol solution evenly, keeping the I / C ratio at 0.9, and fully shear and disperse to obtain catalyst slurry; Step (2): The catalyst slurry is coated onto the proton exchange membrane by slit extrusion to obtain the first catalyst layer; the coating speed is 1 m / min and the coating thickness is 100 µm; after coating, it is dried at room temperature for 120 min at 25 °C; then it is dried in an oven at 80 °C for 30 min. Step (3): Cover the first catalyst layer side of the proton exchange membrane after drying in step (2) with a release membrane and peel off the original bottom membrane of the proton exchange membrane. Then, apply the catalyst slurry onto the proton exchange membrane by slit extrusion to obtain the second catalyst layer. The coating speed is 1 m / min and the coating thickness is 30 µm. After coating, dry at room temperature for 60 min at 25 °C. Then, dry in an oven at 80 °C for 10 min. Finally, remove the release membrane to obtain a catalyst layer with conventional pore size distribution and conventional Pt loading distribution. At this time, the catalyst layer prepared in Comparative Example 2 does not have gradient pore size distribution and gradient Pt loading distribution, and the Pt loading of the first and second catalyst layers prepared in Comparative Example 2 is 0.456 mg•Pt / cm. 2 .

[0042] Furthermore, the first and second catalytic layers are respectively sealed with borders and carbon paper is attached to obtain the membrane electrode.

[0043] Please refer to Table 1, which compares the electrochemical performance of the membrane electrodes prepared in Example 1, Comparative Example 1, and Comparative Example 2.

[0044] Table 1

[0045] Specifically, as can be seen from Table 1, the membrane electrode prepared in Example 1 has a 1A / cm 2 Performance and 2A / cm 2 The performance is superior to Comparative Example 1 and Comparative Example 2, especially in the range of 1–2 A / cm. 2The membrane electrode prepared in Example 1 exhibits the slowest performance degradation rate, indicating that its catalytic layer with gradient pore size distribution and gradient Pt loading distribution has stronger mass transfer capability and can drain water and remove gas in a timely manner even under high current. This is attributed to the unique catalytic layer structure of the membrane electrode prepared in Example 1.

[0046] The above results indicate that the membrane electrode prepared in Example 1, due to the unique gradient pore size and gradient Pt loading distribution structure of the catalyst layer, exhibits high efficiency at 1–2 A / cm². 2 The high current density range exhibits superior performance compared to Comparative Examples 1-2: its inner layer's small pore size and high Pt loading create a high-density active site and short proton conduction pathway, ensuring high catalytic efficiency; the outer layer's large-pore network forms a low-resistance mass transfer channel, simultaneously enabling rapid diffusion of reactant gases and efficient removal of generated water, effectively suppressing concentration polarization and catalyst layer flooding under high current. This gradient structure, through reverse matching of pore size and Pt loading, reduces mass transfer resistance by more than 30%, while simultaneously increasing Pt atom utilization to 85%, and reducing decay rate by 40% compared to Comparative Examples 1 and 2. This verifies the significant role of the gradient structure in optimizing three-phase interface mass transfer kinetics, enhancing hydrothermal management capabilities, and improving durability, providing a structural foundation for the long-term operation of high-power-density fuel cells.

[0047] In summary, unlike existing technologies, the catalyst layer for fuel cells, its preparation method, membrane electrode assembly, and fuel cell provided by this invention have the following advantages: First, this invention employs a Pt / C catalyst slurry containing two different loadings and particle sizes for coating. During room-temperature drying, the catalyst particles undergo vertical rearrangement, with smaller particles and higher Pt content depositing in the lower layer, and larger particles and lower Pt content distributed in the upper layer. This results in a catalyst layer with a gradient pore size and gradient loading distribution. Specifically, the pore size increases and the Pt content decreases from the inside to the outside of the catalyst layer. This gradient pore size and gradient Pt loading distribution improves the mass transfer performance of the catalyst layer and increases Pt utilization.

[0048] Secondly, the method for preparing the catalyst layer for fuel cells provided by this invention is simple, feasible, and easy to industrialize. Furthermore, by adjusting the ratio of the catalyst slurry and coating parameters, the structure and performance of the catalyst layer can be flexibly controlled to meet different application requirements.

[0049] Finally, the membrane electrode and fuel cell prepared using the catalyst layer of the present invention have higher performance and longer service life, and can be widely used in the field of hydrogen energy.

[0050] It should be noted that all the above embodiments belong to the same inventive concept, and the descriptions of each embodiment have different focuses. Where the description in a particular embodiment is not detailed, please refer to the description in other embodiments.

[0051] The above embodiments merely illustrate implementation methods of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for preparing a catalyst layer for a fuel cell, characterized in that, include: S10, the first catalyst, the second catalyst, the Nafion resin solution and the aqueous alcohol solution are mixed evenly to obtain a catalyst slurry; S20, the catalyst slurry is coated on one side of the proton exchange membrane, dried at room temperature, and then dried in an oven to form the first catalyst layer in the catalyst layer; S30, repeat step S20 on the other side of the proton exchange membrane to form a second catalyst layer in the catalyst layer; In step S10, both the first catalyst and the second catalyst are Pt / C catalysts, and the particle size of the first catalyst is smaller than that of the second catalyst, while the Pt content of the first catalyst is greater than that of the second catalyst.

2. The method for preparing the catalyst layer for a fuel cell according to claim 1, characterized in that, In step S10, the particle size of both the first catalyst and the second catalyst is 10-100 nm, and the Pt content of both the first catalyst and the second catalyst is 10%-90%.

3. The method for preparing the catalyst layer for a fuel cell according to claim 1, characterized in that, In step S10, the sum of the masses of the first catalyst and the second catalyst accounts for 5% to 10% of the total mass of the catalyst slurry.

4. The method for preparing a catalyst layer for a fuel cell according to claim 1, characterized in that, In step S20, the drying time for the room temperature drying treatment is 30-180 min, the drying temperature in the drying tunnel is 40-120℃, and the drying time is 2-60 min.

5. The method for preparing a catalyst layer for a fuel cell according to claim 1, characterized in that, The process after step S20 and before step S30 includes: forming a release membrane on the first catalyst layer and peeling off the proton exchange membrane substrate located on the other side of the proton exchange membrane.

6. The method for preparing a catalyst layer for a fuel cell according to claim 5, characterized in that, The release film includes any one of PET, PEN, PEI, PPS, PSU and PPSU, and the temperature resistance range of the release film is 25 to 150°C.

7. The method for preparing a catalyst layer for a fuel cell according to claim 1, characterized in that, The pore sizes of both the first and second catalyst layers increase from the inside to the outside of the proton exchange membrane, and the Pt loading of both the first and second catalyst layers decreases from the inside to the outside of the proton exchange membrane.

8. A catalyst layer for a fuel cell, characterized in that, Prepared by the method for preparing a catalyst layer for a fuel cell as described in any one of claims 1 to 7; The pore sizes of both the first and second catalyst layers are 1 nm to 100 μm; the Pt loading of both the first and second catalyst layers is 0.05 to 1 mg Pt / cm³. 2 .

9. A membrane electrode, characterized in that, It includes the catalyst layer, proton membrane, border membrane and gas diffusion layer as described in claim 8, wherein the border membrane is respectively attached to the first catalyst layer, the second catalyst layer and the proton membrane, and the gas diffusion layer is attached to the border membrane.

10. A fuel cell, characterized in that, Includes the membrane electrode as described in claim 9.

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