A sealing structure of a fuel cell membrane electrode

Abstract

The application relates to a sealing structure of a fuel cell membrane electrode, which comprises a first gas diffusion layer, a second gas diffusion layer, a second frame arranged inside the first gas diffusion layer and the second gas diffusion layer and extending outwards, and a non-horizontal concave-convex upper surface, and a catalyst coating layer laid on the concave-convex surface of the second frame, wherein the catalyst coating layer is composed of a proton membrane and a catalyst layer coated on both sides of the proton membrane. The end of the catalyst coating layer does not exceed the end of the second frame, and the catalyst coating layer is covered with adhesive glue for connecting the first gas diffusion layer, the catalyst coating layer and the second frame. Compared with the prior art, the proton membrane is in a non-linear shape between the frames, the contact path is increased, the service life of the proton membrane is prolonged, the tensile stress of the proton membrane under dry-wet circulation is relieved, and the risk of leakage of the sealing structure is effectively reduced.

Description

Technical Field

[0001] This invention relates to the field of fuel cell component manufacturing technology, and in particular to a sealing structure for a fuel cell membrane electrode. Background Technology

[0002] Proton exchange membrane fuel cells (PEMFCs) are energy conversion devices that directly convert the chemical energy contained in fuel into electrical energy without combustion. The only byproducts of the entire power generation process are water and heat, with no emissions of pollutants such as carbon dioxide. In today's world, where energy and environmental issues are increasingly serious, this is undoubtedly a significant boost, and it is gradually becoming a global research hotspot. Particularly in the automotive industry, an increasing number of fuel cell vehicles are gradually entering the market.

[0003] As the market gradually opens up and applications become more widespread, the market's requirements for the lifespan of fuel cells are also increasing. Regarding the membrane electrode assembly (MEA), a key component, the main lifespan and durability failure modes include performance degradation, hydrogen-air leakage, and external leakage. Performance degradation is primarily affected by the inherent durability characteristics of raw materials such as the catalyst, catalyst layer formulation, and proton exchange membrane; while leakage and external leakage are mainly limited by the mechanical and chemical strength of the proton exchange membrane, stress concentration during structural design, and the adhesive sealing strength between the frame adhesive layer and the proton exchange membrane.

[0004] Patent CN217485502U discloses a membrane electrode encapsulation structure and a fuel cell having the same. The active area windows of the anode and cathode frames are symmetrical. The size of the proton exchange membrane is larger than the size of the cutout windows on both sides of the frame. The periphery of the proton exchange membrane layer overlaps with the frame, with an overlap area width of 2-4 mm. The size of the gas diffusion layers on both sides is the same as the size of the cutout windows on the frame. The gas diffusion layers are placed inside the cutout windows on the frame. However, the proton exchange membrane under this structure is subjected to greater stress concentration at the junction edge of the cutout windows on the frame, which can easily damage the proton exchange membrane and cause leakage of the membrane electrode.

[0005] Patent CN115172832A discloses a fuel cell membrane electrode with a frame-encapsulated structure. By designing the hollowed-out window in the middle of the anode and cathode frame as an asymmetrical structure, the proton exchange membrane's planar dimension is larger than the hollowed-out planar dimension of the frame. A gas diffusion layer on one side is bonded to the outer side of the frame, while the gas diffusion layer on the other side is embedded within the frame's hollowed-out window. Due to the asymmetrical frame design, the proton exchange membrane is only subjected to pressure from the frame's hollowed-out window on one side, while the other side is a flat frame or gas diffusion layer. During encapsulation and use, this reduces the shear stress on the proton exchange membrane at the edge of the frame's hollowed-out window, improving the proton exchange membrane's lifespan. However, the planar dimension of the gas diffusion layer on the other side is consistent with the active area window size, requiring high assembly precision. If the planar dimension of the gas diffusion layer is smaller than the frame's hollowed-out window, gas can easily pass through the gaps in the flow channel, potentially affecting gas distribution and diffusion in the reaction zone. In addition, because the proton exchange membrane swells and shrinks due to humidity, the adhesion between it and the adhesive layer is prone to failure, which may lead to adhesion aging. This can cause gas to bypass the proton exchange membrane and leak to the other side, or water to diffuse through the proton exchange membrane to the outer edge of the frame.

[0006] Patent CN115133065A discloses a novel membrane electrode assembly (MEA) encapsulation structure and method for fuel cells. This structure also employs an asymmetric structure for the anode and cathode active area windows, with one side frame having a larger planar dimension than the other. The proton exchange membrane (PEM) has a larger planar dimension than the cutout area of ​​the frame, but smaller than the smaller frame. The gas diffusion layers on both sides have the same size, larger than the smaller frame but smaller than the larger frame, covering the entire smaller frame and the PEM. This structure alleviates stress concentration on the PEM at the edge of the active area window, and the presence of only one large frame layer outside the gas diffusion layer reduces the risk of bubbles and PEM wrinkles during frame processing. However, the problem of seal failure between the frame and the PEM still exists, allowing gas to leak from the point of adhesion failure to the other side of the PEM. Summary of the Invention

[0007] The purpose of this invention is to overcome the defects of the prior art and provide a sealing structure for a fuel cell membrane electrode.

[0008] The objective of this invention can be achieved through the following technical solutions:

[0009] The technical solution of the present invention is to provide a sealing structure for a fuel cell membrane electrode, including a first gas diffusion layer, a second gas diffusion layer, a frame disposed inside the first gas diffusion layer and the second gas diffusion layer and extending outward, and a catalyst coating layer disposed between the frame and the first gas diffusion layer. The frame includes a second frame that is in close contact with the upper surface of the second gas diffusion layer. The upper surface of the second frame is a non-horizontal concave-convex surface. A hollow is also provided in the middle of the second frame. The catalyst coating layer is disposed between the second frame and the first gas diffusion layer.

[0010] The catalyst coating layer consists of a proton exchange membrane and a catalyst layer coated on both sides of the proton exchange membrane. The catalyst coating layer is laid along the upper surface of the second frame, and the end of the catalyst coating layer does not extend beyond the end of the second frame. The catalyst coating layer is covered with adhesive, which is used to connect and seal the first gas diffusion layer, the catalyst coating layer and the second frame.

[0011] Furthermore, the first gas diffusion layer and the second gas diffusion layer are the same size.

[0012] Furthermore, the surface area of ​​the catalyst layer is smaller than that of the proton exchange membrane.

[0013] Furthermore, the upper surface of the second frame is provided with a plurality of grooves, the catalyst coating layer is laid along the grooves on the upper surface of the second frame, the catalyst coating layer is covered with adhesive, the adhesive at the end of the catalyst coating layer is connected to the end of the second frame, and the adhesive also extends to the top surface of the first gas diffusion layer.

[0014] Furthermore, the distance from the end of the catalyst coating layer to the outer end of the second frame is at least 0.5 mm.

[0015] Furthermore, the frame also includes a first frame that is in close contact with the lower surface of the first gas diffusion layer. The first frame has a hollow in the middle, and the hollow length of the first frame is longer than that of the second frame. The catalyst coating layer is connected and sealed to the upper and lower first and second frames by the adhesive.

[0016] Furthermore, the cutout length of the first frame is 2-10mm longer than the cutout length of the second frame.

[0017] Furthermore, the distance between the end of the first gas diffusion layer and the first frame cutout end located on one side of the end is ≥1mm.

[0018] Furthermore, a first protrusion is provided on the lower surface of the first frame, and a second protrusion is provided on the upper surface of the second frame, which is offset from the first protrusion. A gap is formed between the first frame and the second frame. The catalyst coating layer is laid along the gap, and the catalyst coating layer is connected and sealed to the first frame and the second frame on its upper and lower sides by the adhesive.

[0019] Furthermore, the number of the first bump and the second bump is at least one, and the height of the first bump and the second bump is 0.05-0.5mm.

[0020] Furthermore, when there is only one of each of the first and second protrusions, a Z-shaped gap is formed between the first and second borders; when there is more than one of each of the first and second protrusions, a wavy gap is formed between the first and second borders.

[0021] Compared with the prior art, the present invention has the following beneficial effects;

[0022] (1) The frame in this invention is an asymmetrical frame, which can effectively alleviate the stress concentration of the proton membrane and improve the life of the proton membrane.

[0023] (2) The proton exchange membrane in this invention is non-linear between the frames, which increases the contact path and extends the service life of the proton exchange membrane. It also alleviates the tensile stress of the proton exchange membrane under dry and wet cycles. This invention effectively reduces the risk of leakage in the membrane electrode sealing structure.

[0024] (3) The proton membrane in this invention is shorter than the frame, which can effectively prevent water vapor from diffusing and being transported outside the frame through the proton membrane. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of Example 1.

[0026] Figure 2 This is a schematic diagram of the structure of Example 2.

[0027] Figure 3 This is a schematic diagram of the structure of Example 3.

[0028] The diagram is labeled as follows:

[0029] 1 is the first gas diffusion layer; 2 is the first frame; 2-1 is the first protrusion; 3 is the catalyst coating layer; 4 is the adhesive; 5 is the second frame; 5-1 is the second protrusion; 6 is the second gas diffusion layer. Detailed Implementation

[0030] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0031] In the following embodiments, unless otherwise specified, the functional components or structures are conventional components or structures used in the art to achieve the corresponding functions.

[0032] Example 1:

[0033] like Figure 1 The described structure is a sealing structure for a fuel cell membrane electrode assembly (MEA), comprising a first gas diffusion layer 1, a second gas diffusion layer 6 of the same size as the first gas diffusion layer 1, a second frame 5 that is closely attached to and extends from the upper surface of the second gas diffusion layer 6, and a catalyst coating layer 3 laid between the second frame 5 and the first gas diffusion layer 1. The second frame 5 has a hollow center, and its upper surface is laser-etched with three grooves. The catalyst coating layer 3 consists of a proton exchange membrane and catalyst layers coated on both sides of the proton exchange membrane, with the area of ​​the catalyst layers being smaller than that of the proton exchange membrane. The catalyst coating layer 3 is laid along the grooves on the upper surface of the second frame 5, resulting in a wavy appearance on the upper surface of the second frame 5. The end of the catalyst coating layer 3 does not extend beyond the end of the second frame 5, and the distance to the outer end of the second frame 5 is at least 0.5 mm. An adhesive 4 is applied to the catalyst coating layer 3 and extends to the top surface of the first gas diffusion layer 1, serving to connect and seal the first gas diffusion layer 1, the catalyst coating layer 3, and the second frame 5. The adhesive 4 at the end of the catalyst coating layer 3 is connected to the end of the second frame 5.

[0034] The encapsulation method of the sealing structure in this embodiment is as follows:

[0035] (1) Preparation of catalyst coating layer 3: The anode and cathode catalyst layers are sprayed or transferred on both sides of the proton exchange membrane to form a three-layer catalyst coating layer 3, namely the fuel cell chip (catalyst coated membrane, CCM);

[0036] (2) Preparation of the second frame 5: First, take two pieces of frame material and cut them into two pieces of the required size. Peel off the adhesive release paper of one of the frames and position and attach the large and small frames. Then, punch the active area window as a whole and use laser etching to process multiple grooves.

[0037] (3) The catalyst coating film 3 is laminated onto the groove on the upper surface of the second frame 5 by pressure-sensitive or hot-pressing method;

[0038] (4) Preparation of the first gas diffusion layer 1 and the second gas diffusion layer 6: The gas diffusion layer is cut into the required specifications and sizes of the first gas diffusion layer 1 and the second gas diffusion layer 6 using cutting tools such as die-cutting molds.

[0039] (5) The first gas diffusion layer 1 and the second gas diffusion layer 6 are respectively composited on the outside of the catalyst coating film 3 and the second frame 5.

[0040] (6) Use adhesive 4 to connect and seal the first diffusion layer 1, the catalyst coating layer 3 and the second frame 5 together.

[0041] Example 2:

[0042] like Figure 2 The diagram shows a sealed structure for a fuel cell membrane electrode assembly (MEA), comprising a first gas diffusion layer 1, a second gas diffusion layer 6 of the same size as the first gas diffusion layer 1, a first frame 2 extending from the lower surface of the first gas diffusion layer 1, a second frame 5 extending from the upper surface of the second gas diffusion layer 6, and a catalyst coating layer 3 located between the second frame 5 and the first frame 2. Both the first frame 2 and the second frame 5 have a perforation in the middle, with the perforation length of the first frame 2 being 2-10 mm longer than that of the second frame 5. The distance between the end of the first gas diffusion layer 1 and the perforated end of the first frame 2 located on one side of that end is greater than or equal to 1 mm. The upper surface of the second frame 5 has three grooves formed by laser etching. The catalyst coating layer 3 consists of a proton exchange membrane and catalyst layers coated on both sides of the proton exchange membrane, with the area of ​​the catalyst layer being smaller than that of the proton exchange membrane. The catalyst coating layer 3 is laid along the groove on the upper surface of the second frame 5. At this time, the catalyst coating layer 3 is wavy on the upper surface of the second frame 5. The end of the catalyst coating layer 3 does not exceed the end of the first frame 2 and the second frame 5, and the distance to the outer end of the first frame 2 and the second frame 5 is at least 0.5 mm. Adhesive 4 is filled between the first frame 2 and the catalyst coating layer 3 to connect and seal the first frame 2 and the catalyst coating layer 3. The adhesive 4 at the end of the catalyst coating layer 3 is used to connect and seal the first frame 2 and the second frame 5.

[0043] The encapsulation method of the sealing structure in this embodiment is as follows:

[0044] (1) Preparation of catalyst coating layer 3: The cathode and anode catalyst layers are sprayed or transferred on both sides of the proton membrane to form a three-layer CCM;

[0045] (2) Preparation of the first frame 2: First, take two pieces of frame material and cut them into two pieces of the required size. Peel off the adhesive release paper of the larger frame and attach the larger and smaller frames together. Then, punch the active area window as a whole.

[0046] Preparation of the second frame 5: First, take two pieces of frame material and cut them into two pieces of the required size. Peel off the adhesive release paper of one of the frames and position and attach the large and small frames. Then, punch the active area window as a whole and use laser etching to process multiple grooves.

[0047] (3) The catalyst coating film 3 is laminated onto the groove on the upper surface of the second frame 5 by pressure-sensitive or hot-pressing method, and the first frame 2 is laminated onto the catalyst coating film 3.

[0048] (4) Preparation of the first gas diffusion layer 1 and the second gas diffusion layer 6: The gas diffusion layer is cut into the required specifications and sizes of the first gas diffusion layer 1 and the second gas diffusion layer 6 using cutting tools such as die-cutting molds.

[0049] (5) The first gas diffusion layer 1 and the second gas diffusion layer 6 are respectively bonded to the outside of the first frame 2 and the second frame 5.

[0050] (6) Use adhesive 4 to connect and seal the first frame 2, the catalyst coating layer 3 and the second frame 5 together.

[0051] Example 3:

[0052] like Figure 3 The diagram shows a sealed structure for a fuel cell membrane electrode assembly (MEA), comprising a first gas diffusion layer 1, a second gas diffusion layer 6 of the same size as the first gas diffusion layer 1, a first frame 2 extending from the lower surface of the first gas diffusion layer 1, a second frame 5 extending from the upper surface of the second gas diffusion layer 6, and a catalyst coating layer 3 located between the second frame 5 and the first frame 2. Both the first frame 2 and the second frame 5 have a perforation in the middle, with the perforation length of the first frame 2 being 2-10 mm longer than that of the second frame 5. The distance between the end of the first gas diffusion layer 1 and the perforated end of the first frame 2 located on one side of that end is ≥1 mm. A first protrusion 2-1 with a height of 0.05-0.5mm is provided on the hollow end of the first frame 2, and a second protrusion 5-1 with a height of 0.05-0.5mm is provided at the end of the second frame 5, offset from the first protrusion 2-1. Therefore, a Z-shaped uneven gap is formed between the first frame 2 and the second frame 5. The catalyst coating layer 3 is laid between the first frame 2 and the second frame 5 along the Z-shaped uneven gap. The end of the catalyst coating layer 3 does not exceed the end of the first frame 2 and the second frame 5, and the distance to the outer end of the first frame 2 and the second frame 5 is at least 0.5mm. The adhesive 4 at the end of the catalyst coating layer 3 is used to connect and seal the first frame 2 and the second frame 5.

[0053] The encapsulation method of the sealing structure in this embodiment is as follows:

[0054] (1) Preparation of catalyst coating layer 3: The cathode and anode catalyst layers are sprayed or transferred on both sides of the proton membrane to form a three-layer catalyst coating layer 3;

[0055] (2) Preparation of the first frame 2: First, take two pieces of frame material and cut them into two pieces of the required size. Remove the adhesive release paper of the larger frame and attach the larger and smaller frames together. Then, punch the active area window as a whole and etch the first bump 2-1 with plasma or laser.

[0056] Second border 5: First, take two pieces of border material and cut them into two pieces of the required size. Peel off the release paper of the adhesive layer of the larger border and attach the larger and smaller borders together. Then, punch the active area window as a whole and etch the second protrusion 5-1 with plasma or laser.

[0057] (3) The catalyst coating film 3 is composited in the Z-shaped gap between the first frame 2 and the second frame 5 by pressure-sensitive or hot-pressing method;

[0058] (4) Preparation of the first gas diffusion layer 1 and the second gas diffusion layer 6: The gas diffusion layer is cut into the required specifications and sizes of the first gas diffusion layer 1 and the second gas diffusion layer 6 using cutting tools such as die-cutting molds.

[0059] (5) The first gas diffusion layer 1 and the second gas diffusion layer 6 are respectively bonded to the outside of the first frame 2 and the second frame 5.

[0060] (6) Use adhesive 4 to connect and seal the first frame 2, the catalyst coating layer 3 and the second frame 5 together.

[0061] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A sealing structure of a fuel cell membrane electrode, comprising a first gas diffusion layer (1), a second gas diffusion layer (6), a frame provided inside and extending from the first gas diffusion layer (1) and the second gas diffusion layer (6), and a catalyst-coated layer (3) provided between the frame and the first gas diffusion layer (1), characterized in that, The frame includes a second frame (5) that is in close contact with the upper surface of the second gas diffusion layer (6). The upper surface of the second frame (5) is a non-horizontal concave-convex surface. The second frame (5) also has a hollow in the middle. The catalyst coating layer (3) is provided between the second frame (5) and the first gas diffusion layer (1). The catalyst coating layer (3) consists of a proton membrane and a catalyst layer coated on both sides of the proton membrane. The catalyst coating layer (3) is laid along the upper surface of the second frame (5). The end of the catalyst coating layer (3) does not exceed the end of the second frame (5). The catalyst coating layer (3) is covered with adhesive (4). The adhesive (4) is used to connect and seal the first gas diffusion layer (1), the catalyst coating layer (3) and the second frame (5). The upper surface of the second frame (5) is provided with several grooves. The catalyst coating layer (3) is laid along the grooves on the upper surface of the second frame (5). The adhesive (4) at the end of the catalyst coating layer (3) is connected to the end of the second frame (5). The adhesive (4) also extends to the top surface of the first gas diffusion layer (1).

2. The seal structure for a fuel cell membrane electrode according to claim 1, wherein The first gas diffusion layer (1) and the second gas diffusion layer (6) are the same size.

3. The sealing structure of a fuel cell membrane electrode according to claim 1, characterized in that, The surface area of ​​the catalyst layer is smaller than that of the proton exchange membrane.

4. The seal structure for a fuel cell membrane electrode according to claim 1, wherein The distance from the end of the catalyst coating layer (3) to the outer end of the second frame (5) is at least 0.5 mm.

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