A method for preparing a gradient wettable gas diffusion layer to improve the water balance of AEMFC

Abstract

This invention belongs to the technical field of anion exchange membrane fuel cells (AEMFCs) and discloses a method for preparing a gradient wettable gas diffusion layer to improve the water balance of AEMFCs. The method includes: S1, cleaning the initial gas diffusion layer of the AEMFC with deionized water and then drying it for later use; S2, covering the outer surface of the microporous layer of the initial gas diffusion layer with a mask to form a composite, wherein the mask pattern of the mask is designed to have multiple spaced and parallel-extending slits; S3, performing oxygen plasma treatment on the composite, thereby causing the area irradiated by the oxygen plasma to become hydrophilic, while the area blocked by the mask retains its original hydrophobicity; S4, allowing it to cool to room temperature, thereby obtaining the desired gas diffusion layer. This invention can significantly optimize the water vapor distribution state inside the AEMFC through a controllable and repeatable process, improving the battery's water balance regulation capability, and is therefore particularly suitable for improving the overall performance of AEMFCs under various humidity conditions.

Description

Technical Field

[0001] This invention belongs to the technical field of anion exchange membrane fuel cell (AEMFC), and more specifically, relates to a method for preparing a gradient wettable gas diffusion layer to improve the water balance of AEMFC. Background Technology

[0002] The global energy structure is rapidly transitioning towards a low-carbon model, and fuel cells are key equipment for achieving the "electricity-hydrogen-electricity" green energy conversion, serving as a core support for promoting clean energy development. Among these, cryogenic fuel cells offer advantages such as fast response, high flexibility, simple structure, small size, high safety, and ease of maintenance, showing broad application prospects in portable devices, ground transportation, and aerospace. Compared to traditional alkaline fuel cells (AFCs), anion exchange membrane fuel cells (AEMFCs) effectively overcome the defects associated with electrolyte leakage, corrosion, and carbonate precipitation. Compared to proton exchange membrane fuel cells (PEMFCs), they do not rely on precious metal catalysts, do not require fluorinated ion exchange membranes, and exhibit reduced corrosivity, potentially significantly overcoming cost bottlenecks and possessing irreplaceable technological advantages.

[0003] More specifically, AEMFCs and PEMFCs share similar overall structures, both containing core components such as flow field plates, gas diffusion layers, catalyst layers, and ion exchange membranes. The key difference lies in the AEMFC's use of anion exchange membranes instead of proton exchange membranes, resulting in an alkaline operating environment within the battery. From a reaction mechanism perspective, during operation, for every four electrons transferred, the anode produces four water molecules, while the cathode consumes two. In contrast, in PEMFCs, for every four electrons transferred, only two water molecules are produced at the cathode. Therefore, under constant current conditions, the anode water production rate in AEMFCs is twice that of the cathode in PEMFCs. This characteristic can lead to severe water management imbalances within AEMFCs—for example, the anode is prone to flooding, hindering reactant gas transport; the cathode is prone to drying out, affecting ion conduction efficiency. These two problems collectively restrict the improvement of the performance and durability of anion exchange membrane fuel cells, becoming the core bottleneck in the development of AEMFCs.

[0004] Accordingly, further research and improvements are urgently needed in this field to better address the aforementioned technical challenges of anion exchange membrane fuel cells. Summary of the Invention

[0005] To address one or more of the above-mentioned deficiencies or needs in the prior art, this invention provides a method for preparing a gradient wettability gas diffusion layer to improve the water balance of an AEMFC. This method involves fully integrating the structural and performance characteristics of the gas diffusion layer and, based on this, designing its gradient wettability function. Consequently, it can significantly optimize the water vapor distribution within the AEMFC, improve the battery's water balance control capability, and possess advantages such as process controllability, good repeatability, and high system stability. Therefore, it is particularly suitable for improving the overall performance of AEMFCs under various humidity conditions.

[0006] To achieve the above objectives, according to the present invention, a method for preparing a gradient wettability gas diffusion layer to improve the water balance of an AEMFC is provided, wherein the method includes the following steps: S1. The initial gas diffusion layer of the anion exchange membrane fuel cell is cleaned with deionized water and then dried for later use; wherein, the initial gas diffusion layer is composed of an upper and lower stacked microporous layer and a substrate layer. S2. The microporous layer of the initial gas diffusion layer is placed facing upwards, and a mask is placed over the outer surface of the microporous layer, with them in contact to form a composite; wherein the mask pattern of the mask is designed to have multiple slits spaced apart from each other and extending in parallel. S3. The composite is placed in a plasma cleaner and oxygen is used as the cleaning gas to perform oxygen plasma treatment, thereby causing the area irradiated by the oxygen plasma to become hydrophilic, while the area blocked by the mask plate retains its original hydrophobicity, thus forming a pattern of alternating hydrophilic and hydrophobic regions. During this process, the cleaning power is set to 100 W to 300 W, the cleaning time is 1 min to 10 min, and the oxygen flow rate is controlled to 50 mL / min to 100 mL / min. S4. After removing the mask from the gas diffusion layer treated with oxygen plasma, take it out and let it cool to room temperature to obtain the desired final gas diffusion layer.

[0007] This design is primarily based on the consideration that the gas diffusion layer, as a core functional component of the AEMFC, plays a crucial role in distributing reactant gases, removing waste gases and liquid water, and transferring electrons and heat. Its core characteristics, such as wettability and pore structure, directly determine the battery's water management efficiency and overall performance. While existing solutions have continuously improved AEMFC performance, they still fall short of the demands of practical engineering applications, and water management remains a key factor limiting its power density and durability. Therefore, this invention creatively proposes optimizing the internal water balance of the battery through precise design of the gas diffusion layer's wettability, and studies this as one of the important technical pathways to improve AEMFC performance.

[0008] More specifically, through the above concept, on the one hand, after oxygen plasma treatment, the contact angle of the microporous layer in the oxygen plasma-irradiated area of ​​the gas diffusion layer is significantly reduced, while the contact angle in the shielded area of ​​the microporous layer remains basically unchanged or decreases only slightly. This forms multiple parallel gradient wetting structures spaced apart from each other on the entire outer surface of the microporous layer, providing independent water vapor transport paths. On the other hand, when the anion exchange membrane fuel cell operates under various humidity conditions, the water generated in the catalyst layer is preferentially transported to the aforementioned hydrophilic region (containing multiple hydrophilic channels) for rapid discharge, while the hydrophobic region can maintain unobstructed pores, ensuring efficient gas transport. The two work together to significantly optimize the water vapor distribution state inside the AEMFC and improve the battery's water balance control capability.

[0009] As a further preferred embodiment of the present invention, in step S1, the initial gas diffusion layer is a commercially available existing gas diffusion layer.

[0010] As a further preferred embodiment of the present invention, in step S2, the mask plate has a flat plate structure and is made of stainless steel.

[0011] As a further preferred embodiment of the present invention, in step S2, the mask pattern of the mask plate has multiple slits that are spaced apart from each other and extend in parallel, and the width of each slit is 0.5 mm to 1 mm, and the interval between adjacent slits is 0.5 mm to 3 mm.

[0012] As a further preferred embodiment of the present invention, in step S2, the mask is preferably fixed by a clamp to ensure that it covers the outer surface of the microporous layer and is in close contact.

[0013] As a further preferred embodiment of the present invention, in step S3, the area irradiated by oxygen plasma contains multiple hydrophilic channels, and the water generated by the catalyst layer of the anion exchange membrane fuel cell is preferentially transported to these hydrophilic channels for rapid discharge.

[0014] As a further preferred embodiment of the present invention, in step S3, the area blocked by the mask plate is used as a hydrophobic area to ensure gas transmission in the anion exchange membrane fuel cell.

[0015] As a further preferred embodiment of the present invention, for anion exchange membrane fuel cells employing the above-mentioned gas diffusion layer, their performance can be improved by up to approximately 36.3% in the range of relative humidity from 100% to 70%.

[0016] In summary, compared with the prior art, the above-described technical solutions conceived by this invention mainly possess the following technical advantages: (1) The technological innovation of this invention lies first in the targeted design of the working mechanism of the entire preparation process. In this process, a gradient wetting structure with hydrophilic and hydrophobic regions distributed at intervals is constructed on the microporous layer. This structure can provide independent water and gas transport paths. Specifically, the water generated by the catalyst layer will be preferentially transported to the hydrophilic region of the gas diffusion layer and quickly discharged along the hydrophilic channel. The hydrophobic region can keep the pores open and ensure efficient gas transport. Compared with the prior art, this working method significantly improves the two-phase transport efficiency of the gas diffusion layer, improves the battery water balance control capability, and thus helps the working performance of AEMFC. (2) The above preparation route designed in this invention is simple, easy to control, flexible and repeatable because it only uses a mask plate + oxygen plasma treatment method. It can be well applied to various types of existing gas diffusion layers. It can also ensure that the gradient wetting structure with hydrophilic and hydrophobic regions is distributed in intervals to meet the high-precision size requirements. Furthermore, the process parameters can be adjusted and managed in a controllable manner according to specific needs, which can further improve the accuracy of battery water balance control. (3) The preparation method of the present invention can accurately construct a gradient wetting structure on the gas diffusion layer, which is the core functional component of AEMFC, significantly optimize the internal water vapor distribution state of the anion exchange membrane fuel cell, and effectively improve the overall performance of the battery under various humidity conditions. Some test data show that the gas diffusion layer can promote the performance improvement of the anion exchange membrane fuel cell by up to 36.3% in the relative humidity range of 100% to 70%. Therefore, as one of the important technical paths to improve the performance of AEMFC, it has important research value and application prospects. Attached Figure Description

[0017] Figure 1 This is a process flow diagram of the method for preparing a gradient wettable gas diffusion layer to improve the water balance of AEMFC according to the present invention; Figure 2 It is a scene diagram used to specifically show the preparation method according to the present invention; Figure 3 This is an exemplary diagram showing the results of contact angle testing on the untreated and treated areas of a sample prepared according to Example 1 of the present invention; Figure 4a This is an exemplary display of the performance curves of samples prepared according to Examples 1 and 2 of the present invention after being used in AEMFC at 100% RH; Figure 4b This is an exemplary display of the performance curves of samples prepared according to Examples 1 and 2 of the present invention after being used in AEMFC at 90% RH; Figure 4cThis is an exemplary display of the performance curves of samples prepared according to Examples 1 and 2 of the present invention after being used in AEMFC at 80% RH; Figure 4d This is an exemplary display of the performance curves of samples prepared according to Examples 1 and 2 of the present invention after being used in AEMFC at 70% RH. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0019] It should be understood that expressions such as "comprising" and "may include" as used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as "comprising" and / or "having" may be interpreted as indicating a specific characteristic, number, operation, constituent element, component, or combination thereof, but should not be interpreted as excluding the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0020] It should be understood that the terms “center,” “upper,” “lower,” “front,” “rear,” “left,” “right,” “vertical,” “horizontal,” “inner,” “outer,” “clockwise,” “counterclockwise,” “axial,” “radial,” and “circumferential” indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0021] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0022] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0023] Figure 1 This is a process flow diagram of the method for preparing a gradient wettability gas diffusion layer to improve the water balance of AEMFC according to the present invention. Figure 2 This is a scene diagram used to specifically illustrate the preparation method according to the present invention. Reference will be made below. Figure 1 and Figure 2 This will be explained in more detail to illustrate the present invention.

[0024] like Figure 1 As shown, this invention fully integrates the structural and performance characteristics of the gas diffusion layer and addresses various shortcomings in existing technologies by providing a method for preparing a gradient wettability gas diffusion layer to improve the water balance of an AEMFC. The aim is to optimize the internal water balance of the battery through precise design of the wettability of the gas diffusion layer. This method mainly includes the following steps: First, the initial gas diffusion layer of the anion exchange membrane fuel cell is cleaned with deionized water and then dried for later use; wherein, the initial gas diffusion layer is composed of an upper and lower stacked microporous layer and a substrate layer; In this step, the initial gas diffusion layer can be directly selected from various commercially available existing gas diffusion layers; such as Figure 2 As shown, its microporous layer and base layer are respectively in the form of a plate-like structure, and their specific composition and composition method will not be described in detail here.

[0025] Next, the microporous layer of the initial gas diffusion layer is placed facing upwards, and a mask is placed over the outer surface of the microporous layer, with them in contact to form a composite; wherein the mask pattern of the mask is designed to have multiple slits spaced apart from each other and extending in parallel. More specifically, such as Figure 2 As shown, the mask plate is, for example, a flat plate structure and is made of stainless steel. Furthermore, according to a preferred embodiment of the invention, the mask pattern of the mask plate has multiple spaced-apart and parallel-extending slits, and the width of each slit is preferably set to 0.5 mm to 1 mm, and the spacing between adjacent slits is preferably set to 0.5 mm to 3 mm.

[0026] Next, the composite is placed in a plasma cleaner and oxygen plasma treatment is performed using oxygen as the cleaning gas. This causes the area irradiated by the oxygen plasma to become hydrophilic, while the area blocked by the mask retains its original hydrophobicity. In this way, a gradient wetting structure can be obtained, and this gradient wetting structure will significantly improve the two-phase transport efficiency of the gas diffusion layer.

[0027] More specifically, after oxygen plasma treatment, the contact angle of the microporous layer in the oxygen plasma-irradiated area of ​​the gas diffusion layer is significantly reduced, while the contact angle in the shielded area of ​​the microporous layer remains basically unchanged or decreases only slightly. This forms multiple spaced and parallel gradient wetting structures on the entire outer surface of the microporous layer, providing independent water vapor transport paths. Based on this, when the anion exchange membrane fuel cell operates under various humidity conditions, the water generated in the catalyst layer is preferentially transported to the aforementioned hydrophilic region (containing multiple hydrophilic channels) for rapid discharge, while the hydrophobic region maintains unobstructed pores, ensuring efficient gas transport. The two work together to significantly optimize the water vapor distribution state inside the AEMFC and improve the battery's water balance control capability.

[0028] According to another preferred embodiment of the present invention, in this process, the cleaning power is set to 100 W to 300 W, the cleaning time is 1 min to 10 min, and the oxygen flow rate is controlled to be 50 mL / min to 100 mL / min; Finally, the gas diffusion layer treated with oxygen plasma is removed from the mask and allowed to cool to room temperature to obtain the desired final gas diffusion layer.

[0029] Several specific embodiments will be given below to explain the present invention more clearly.

[0030] Example 1 The commercially available gas diffusion layer SGL36BB to be treated was cleaned with deionized water to remove surface contaminants and dried for later use. The microporous layer of the gas diffusion layer was placed facing upwards, and a stainless steel mask was placed over the microporous layer and secured with small clips to ensure good contact between the gas diffusion layer and the mask. The slit width of the mask was 1 mm, and the slit spacing was 1 mm.

[0031] Next, the composite was placed on the sample holder in the chamber of a plasma cleaner, the chamber door was closed, and the plasma cleaner was used for 3 minutes at a cleaning power of 100 W. Oxygen was used as the cleaning gas, and the oxygen flow rate was controlled at 60 mL / min. Finally, the treated gas diffusion layer was removed and allowed to cool to room temperature.

[0032] Example 2 The commercially available gas diffusion layer SGL36BB to be treated was cleaned with deionized water to remove surface contaminants and dried for later use. The microporous layer of the gas diffusion layer was placed facing upwards, and a stainless steel mask was placed over the microporous layer and secured with small clips to ensure good contact between the gas diffusion layer and the mask. The slit width of the mask was 0.5 mm, and the slit spacing was 1 mm.

[0033] Next, the composite was placed on the sample holder in the cavity of a plasma cleaner, the cavity door was closed, and it was treated in the plasma cleaner for 5 minutes at a cleaning power of 100 W. Oxygen was used as the cleaning gas, and the oxygen flow rate was controlled at 60 mL / min. Finally, the treated gas diffusion layer was removed and allowed to cool to room temperature.

[0034] Example 3 The commercially available gas diffusion layer SGL36BB to be treated was cleaned with deionized water to remove surface contaminants and dried for later use. The microporous layer of the gas diffusion layer was placed facing upwards, and a stainless steel mask was placed over the microporous layer and secured with small clips to ensure good contact between the gas diffusion layer and the mask. The slit width of the mask was 1 mm, and the slit spacing was 2 mm.

[0035] Next, the composite was placed on the sample holder in the cavity of a plasma cleaner, the cavity door was closed, and it was treated in the plasma cleaner for 5 minutes at a cleaning power of 200 W. Oxygen was used as the cleaning gas, and the oxygen flow rate was controlled at 50 mL / min. Finally, the treated gas diffusion layer was removed and allowed to cool to room temperature.

[0036] Example 4 The commercially available gas diffusion layer SGL36BB to be treated was cleaned with deionized water to remove surface contaminants and dried for later use. The microporous layer of the gas diffusion layer was placed facing upwards, and a stainless steel mask was placed over the microporous layer and secured with small clips to ensure good contact between the gas diffusion layer and the mask. The slit width of the mask was 1 mm, and the slit spacing was 3 mm.

[0037] Next, the composite was placed on the sample holder in the chamber of a plasma cleaner, the chamber door was closed, and the plasma cleaner was used for 1 minute at a cleaning power of 200 W. Oxygen was used as the cleaning gas, and the oxygen flow rate was controlled at 100 mL / min. Finally, the treated gas diffusion layer was removed and allowed to cool to room temperature.

[0038] Example 5 The commercially available gas diffusion layer SGL28BC to be treated was cleaned with deionized water to remove surface contaminants and dried for later use. The microporous layer of the gas diffusion layer was placed facing upwards, and a stainless steel mask was placed over the microporous layer and secured with small clips to ensure good contact between the gas diffusion layer and the mask. The slit width of the mask was 1 mm, and the slit spacing was 1 mm.

[0039] Next, the composite was placed on the sample holder in the chamber of a plasma cleaner, the chamber door was closed, and the plasma cleaner was used for 3 minutes at a cleaning power of 100 W. Oxygen was used as the cleaning gas, and the oxygen flow rate was controlled at 60 mL / min. Finally, the treated gas diffusion layer was removed and allowed to cool to room temperature.

[0040] Example 6 The commercially available gas diffusion layer SGL28BC to be treated was cleaned with deionized water to remove surface contaminants and dried for later use. The microporous layer of the gas diffusion layer was placed facing upwards, and a stainless steel mask was placed over the microporous layer and secured with small clips to ensure good contact between the gas diffusion layer and the mask. The slit width of the mask was 0.5 mm, and the slit spacing was 0.5 mm.

[0041] Next, the composite was placed on the sample holder in the cavity of a plasma cleaner, the cavity door was closed, and the plasma cleaner was used for 10 minutes at a cleaning power of 300 W. Oxygen was used as the cleaning gas, and the oxygen flow rate was controlled at 50 mL / min. Finally, the treated gas diffusion layer was removed and allowed to cool to room temperature.

[0042] Using the gas diffusion layer prepared in Example 1 as a sample, the hydrophilic contact angle of its hydrophilic and hydrophobic regions was tested separately. Figure 3 The test results show that the contact angle of the microporous layer decreased by 22.3° after plasma treatment, while the contact angle of the substrate layer decreased by only 3.9°. This indicates that oxygen plasma treatment can significantly improve the hydrophilicity of the microporous layer, while having little effect on the hydrophobicity of the substrate layer.

[0043] Using the gas diffusion layer prepared in Example 1 as a sample, it was applied to a membrane electrode assembly. This membrane electrode assembly, for example, has a 3 cm... With an active surface area of ​​3 cm², Premetek's 60% PtRu / C was used as the anode catalyst, and Johnson Matthey's 40% Pt / C as the cathode catalyst. The noble metal loading at both the anode and cathode was designed to be 0.32 mg / cm². 2 The catalyst utilization rate is 50%, the anion exchange membrane is PiperION-A20-HCO3, and the anode and cathode ionomers are both PiperION-C5-HCO3.

[0044] The prepared catalyst was coated onto anion exchange membrane and placed in a plastic measuring cup containing 250 mL of 1M NaOH solution. The cup was sealed and incubated at 25 °C for 12–18 h. After ion exchange, the membrane was rinsed 2–3 times in deionized water to remove surface alkali. The sample from Example 1 was then used as the cathode and anode gas diffusion layer, with the wettability stripes perpendicular to the fluid flow direction. The membrane electrode was assembled directly without hot pressing to obtain the membrane electrode assembly. To ensure good contact between the membrane electrode components and maintain the stability of the GDL pore structure, the thickness of the PTFE sealing frame was designed to be 75% of the GDL thickness to maintain a uniform 25% compression of the gas diffusion layer. During assembly, all bolts were 40 kgf. Tighten with a torque of cm. A rigorous airtightness test must be conducted before testing to ensure the safety of the experimental process.

[0045] In addition, an 850e fuel cell test system equipped with a manual backpressure module was used to test the performance curves of anion exchange membrane fuel cells. The cell temperature was controlled at 70 °C, the relative humidity of the gas was 100%–70%, the anode reactant was hydrogen, and the cathode reactant was oxygen, both at a flow rate of 1.0 L / min. After each change in test conditions, a 10-minute rebalancing period was required before testing. Performance was measured first under high humidity, and then gradually decreased to test performance under low humidity to avoid irreversible performance degradation due to membrane dehydration, which could distort the test results.

[0046] Based on this, using untreated SGL36BB carbon paper as a comparative example, the gas diffusion layers of Example 1 and the comparative example were washed in deionized water and then assembled with the membrane electrode in a test fixture to obtain an anion exchange membrane fuel cell. Figures 4a to 4d The performance curves shown sequentially indicate that the comparative example results in a peak power density of 1.000 W / cm³ at 100% RH (relative humidity), 90% RH, 80% RH, and 70% RH. 2 0.949 W / cm², 0.903 W / cm² 2 0.702 W / cm 2 Example 1 resulted in peak power densities of 1.036 W / cm² at 100% RH, 90% RH, 80% RH, and 70% RH. 2 1.030 W / cm², 1.008 W / cm² 2 0.863 W / cm 2 Therefore, this gradient wettable gas diffusion layer resulted in a peak power density increase of up to 22.93%.

[0047] The sample prepared in Example 2 can also be tested following the same procedure. Test results show that the peak power density of the anion exchange membrane fuel cell at 100% RH, 90% RH, 80% RH, and 70% RH is 1.044 W / cm³. 2 1.078 W / cm², 1.029 W / cm² 2 0.957 W / cm 2 Therefore, this gradient wettable gas diffusion layer resulted in a peak power density increase of up to 36.32%.

[0048] In summary, the method for preparing a gradient wettability gas diffusion layer to improve the water balance of an AEMFC, designed according to the present invention, can significantly optimize the water vapor distribution state inside the AEMFC and improve the battery's water balance regulation capability by making targeted designs for its gradient wettability function. Therefore, it is particularly suitable for improving the overall performance of AEMFC under various humidity conditions and has good versatility and promotion value.

[0049] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a gradient wettability gas diffusion layer to improve the water balance of an AEMFC, characterized in that, The method includes the following steps: S1. The initial gas diffusion layer of the anion exchange membrane fuel cell is cleaned with deionized water and then dried for later use; wherein, the initial gas diffusion layer is composed of an upper and lower stacked microporous layer and a substrate layer. S2. The microporous layer of the initial gas diffusion layer is placed facing upwards, and a mask is placed over the outer surface of the microporous layer, with them in contact to form a composite; wherein the mask pattern of the mask is designed to have multiple slits spaced apart from each other and extending in parallel. S3. The composite is placed in a plasma cleaner and oxygen is used as the cleaning gas to perform oxygen plasma treatment, thereby causing the area irradiated by the oxygen plasma to become hydrophilic, while the area blocked by the mask plate retains its original hydrophobicity, thus forming a pattern of alternating hydrophilic and hydrophobic regions. During this process, the cleaning power is set to 100 W to 300 W, the cleaning time is 1 min to 10 min, and the oxygen flow rate is controlled to 50 mL / min to 100 mL / min. S4. After removing the mask from the gas diffusion layer treated with oxygen plasma, take it out and let it cool to room temperature to obtain the desired final gas diffusion layer.

2. The method as described in claim 1, characterized in that, In step S1, the initial gas diffusion layer is a commercially available existing gas diffusion layer.

3. The method as described in claim 1 or 2, characterized in that, In step S2, the mask has a flat plate structure and is made of stainless steel.

4. The method according to any one of claims 1 to 3, characterized in that, In step S2, the mask pattern of the mask plate has multiple slits that are spaced apart from each other and extend in parallel, and the width of each slit is 0.5 mm to 1 mm, and the interval between adjacent slits is 0.5 mm to 3 mm.

5. The method according to any one of claims 1 to 4, characterized in that, In step S2, the mask is preferably fixed by a clamp to ensure that it covers the outer surface of the microporous layer and is in close contact.

6. The method according to any one of claims 1 to 5, characterized in that, In step S3, the area irradiated by oxygen plasma contains multiple hydrophilic channels, and the water generated by the catalyst layer of the anion exchange membrane fuel cell is preferentially transported to these hydrophilic channels for rapid discharge.

7. The method as described in claim 6, characterized in that, In step S3, the area blocked by the mask plate is used as a hydrophobic area to ensure gas transmission in the anion exchange membrane fuel cell.

8. The method as described in claim 4, characterized in that, For anion exchange membrane fuel cells employing the aforementioned gas diffusion layer, their performance can be improved by up to approximately 36.3% within a relative humidity range of 100% to 70%.

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