Membrane electrode assembly and fuel cell stack core

Abstract

The present invention relates to a membrane electrode assembly and a fuel cell stack core. The membrane electrode assembly includes a first diffusion membrane, a second diffusion membrane, and a proton membrane. The first and second diffusion membranes are arranged on the upper and lower sides of the proton membrane. The membrane electrode assembly also includes a support frame. The support frame is a frame structure with a hollow center that surrounds the four sides of the proton membrane. The support frame is divided into a first frame area, a second frame area, and a third frame area from the inner circle to the outer circle. The top surface of the second frame area is higher than the top surface of the third frame area, and the top surface of the first frame area is lower than the top surface of the second frame area, forming an installation groove. The four sides of the proton membrane are fixed in the installation groove. The outer bottom of the first diffusion membrane is in contact with the top of the second frame area. The second diffusion membrane is semi-submerged and installed on the lower side of the support frame. Compared with the existing technology, the present invention has the advantages of simplified structure and process, reduced manufacturing costs, and application in large-scale production.

Description

Technical Field

[0001] The present invention relates to the field of fuel cells, and in particular to a membrane electrode assembly and a fuel cell stack core. Background Art

[0002] A fuel cell is a power generation device that generates electricity through an electrochemical reaction between hydrogen and oxygen. It boasts numerous advantages, including high energy conversion efficiency, environmental friendliness, and low noise. With the development and commercialization of fuel cell technology, the safety and durability of fuel cells are receiving increasing attention.

[0003] The existing fuel cell membrane electrode (MEA) assembly usually adopts a four-frame overlapping structure. Figure 3 As shown, the proton membrane is sandwiched between two A-frames, and a diffusion membrane with a B-frame is placed on the outer layers of the two A-frames, and the outermost edges of the A and B frames are bonded together. This structure of the membrane electrode assembly has many frames, resulting in a complex manufacturing process and high manufacturing costs, which is not conducive to large-scale and mass production of fuel cells. Summary of the Invention

[0004] The purpose of the present invention is to provide a membrane electrode assembly and a fuel cell stack in order to overcome the defects of the above-mentioned prior art.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] A membrane electrode assembly comprises a first diffusion membrane, a second diffusion membrane and a proton membrane, wherein the first diffusion membrane and the second diffusion membrane are arranged on the upper and lower sides of the proton membrane, and further comprises a supporting frame, wherein the supporting frame is a frame structure with a central hollow, surrounding the four sides of the proton membrane, and the supporting frame is divided into a first frame area, a second frame area and a third frame area from the inner circle to the outer circle, wherein the top surface of the second frame area is higher than the top surface of the third frame area, and the top surface of the first frame area is lower than the top surface of the second frame area to form a mounting groove, wherein the four sides of the proton membrane are fixed in the mounting groove; the first diffusion membrane is mounted on the upper side of the supporting frame, and the outer bottom of the first diffusion membrane is in contact with the top of the second frame area; the second diffusion membrane is semi-submerged mounted on the lower side of the supporting frame, and the outer end surface of the second diffusion membrane is in contact with the inner end surface of the supporting frame.

[0007] Furthermore, the outer end surface of the first diffusion film is flush with the boundary edge between the second frame area and the third frame area.

[0008] Furthermore, a glue layer is provided between the first diffusion membrane and the top surface of the second frame area, and the glue layer extends between the proton membrane and the first diffusion membrane.

[0009] Furthermore, a glue layer is provided between the proton membrane and the top surface of the first frame region, and the glue layer extends between the proton membrane and the second diffusion membrane.

[0010] Furthermore, the top surfaces of the first frame region and the second frame region have a roughness higher than that of the top surface of the third frame region.

[0011] A fuel cell stack core comprises a bipolar plate and a membrane electrode assembly as described above, wherein a plurality of bipolar plates and a plurality of membrane electrode assemblies are stacked, and support mechanisms are provided on both sides of the bipolar plates, and the support mechanisms are attached to the upper side or the lower side of the membrane electrode assembly.

[0012] Furthermore, sealing mechanisms are provided on both sides of the bipolar plate, and the outer ring of the third frame area is further divided into a fourth frame area, and the sealing mechanism is used to fit the top surface or bottom surface of the fourth frame area.

[0013] Furthermore, the thickness of the third frame region is smaller than the thickness of the fourth frame region, so that the top surface and the bottom surface of the fourth frame region are raised relative to the top surface and the bottom surface of the third frame region.

[0014] Furthermore, it includes at least three membrane electrode assemblies.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] 1) This invention redesigns the overall structure of the membrane electrode assembly, enabling assembly of the first, second, and proton membranes through a single support frame. This simplifies the structure and process, facilitating reduced manufacturing costs and enabling large-scale production. Furthermore, the support frame is divided into a first, second, and third frame region, creating corresponding installation spaces. The proton membrane is directly clamped between the diffusion membrane and the support frame, ensuring stable installation of the proton and diffusion membranes. Furthermore, the first and second diffusion membranes employ an asymmetric design for foolproofing, facilitating differentiation between process steps and improving production efficiency.

[0017] 2) The present invention can provide a glue layer to increase structural strength, and the glue layer can simultaneously connect the diffusion membrane, the proton membrane and the support frame, which is conducive to simplifying the process steps.

[0018] 3) The top surfaces of the first frame area and the second frame area have a certain degree of roughness to improve the installation strength.

[0019] 4) In the core composed of the membrane electrode assembly of the present invention, the bipolar plate has a supporting mechanism that cooperates with the membrane electrode assembly to provide structural support, taking into account both positioning and installation convenience. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1Schematic diagram of the structure of a fuel cell stack.

[0021] Figure 2 A partially enlarged schematic diagram of a fuel cell stack core.

[0022] Figure 3 Schematic diagram of the structure of an existing membrane electrode assembly.

[0023] Figure numerals: 1. first diffusion membrane, 2. second diffusion membrane, 3. proton membrane, 4. supporting frame, 4a. first frame area, 4b. second frame area, 4c. third frame area, 4d. fourth frame area, 5. glue layer, 6. bipolar plate, 61. supporting mechanism, 62. sealing mechanism. DETAILED DESCRIPTION

[0024] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0025] like Figure 1 and Figure 2 As shown, this embodiment provides a fuel cell stack core comprising at least three membrane electrode assemblies and corresponding bipolar plates 6. Multiple bipolar plates 6 and multiple membrane electrode assemblies are stacked. Each membrane electrode assembly comprises a first diffusion membrane 1, a second diffusion membrane 2, a proton membrane 3, and a support frame 4. The proton membrane 3 is a PEM, comprising a catalyst layer coated on both sides of the PEM; the diffusion membrane is made of carbon paper or carbon fiber cloth, with a microporous layer disposed on the surface of the carbon paper or carbon fiber cloth; and the support frame 4 is a rectangular plastic frame structure of a certain thickness, obtained by cutting or punching a plastic sheet, removing the central region and retaining only the edges. The material of the support frame 4 can be one or more of polyester, polyamide, polyphenylene sulfide, polysulfone, and polyimide plastics, preferably a polyester or polyimide plastic film or sheet. The thickness of the support frame 4 can range from 12.5 to 350 μm, preferably 200 μm.

[0026] The support frame 4 is divided into a first frame area 4a, a second frame area 4b, a third frame area 4c and a fourth frame area 4d from the inner circle to the outer circle. The first frame area 4a is the overlapping area of the support frame 4 and the proton membrane 3. The top surface of the first frame area 4a is lower than the top surface of the second frame area 4b to form a mounting groove, and the four sides of the proton membrane 3 are fixed in the mounting groove. Glue is applied on the top surface of the first frame area 4a to form a glue layer 5, so that the top surface of the first frame area 4a and the proton membrane 3 are bonded. The thickness of the proton membrane 3 and the glue layer 5 is equivalent to the depth of the first frame area 4a. The thickness of the proton membrane 3 is generally 15 to 40um. Considering that the thickness of the glue layer 5 is about 5 to 30um, the first frame area 4a is about 5 to 100um deeper than the second frame area 4b.

[0027] The diffusion membranes are disposed on the upper and lower surfaces of the proton membrane 3 and are respectively connected to the support frame 4. Specifically, the first diffusion membrane 1 is disposed on the upper surface of the proton membrane 3 and has a larger area than the proton membrane 3. The portion of the diffusion membrane 1 that extends beyond the proton membrane 3 overlaps the top surface of the second frame region 4b and is glued together. The second diffusion membrane 2 is disposed on the lower surface of the proton membrane 3 and has a smaller area than the proton membrane 3. The second diffusion membrane 2 is semi-submerged within the hollow area of the support frame 4, with the outer end surface of the second diffusion membrane 2 partially abutting the inner end surface of the support frame 4. To enhance the strength of the connection, the glue layer 5 between the proton membrane 3 and the top surface of the first frame region 4a is extended to allow for partial adhesion between the edge of the second diffusion membrane 2 and the proton membrane 3. This extension is 1 to 5 mm. Simultaneously, the glue layer 5 between the first diffusion membrane 1 and the top surface of the second frame region 4b is also extended inward by 1 to 5 mm, allowing for the edge of the first diffusion membrane 1 to also adhere to the proton membrane 3.

[0028] Thus, the first frame region 4a inhibits horizontal movement of the proton membrane 3. The depth of the first frame region 4a, as described above, and the placement of the diffusion membranes on both sides of the proton membrane 3, inhibit vertical movement of the proton membrane 3. The first diffusion membrane 1 is larger in area than the proton membrane 3. The margins of the first diffusion membrane 1, which extend beyond the proton membrane 3, are bonded to the support frame 4, increasing bonding strength and improving the structural strength of the proton membrane 3 assembly. In this embodiment, the second diffusion membrane 2 is embedded in the middle of the support frame 4 and closely adheres to the lower surface of the proton membrane 3. This effectively saves space while ensuring strength, thereby increasing the volumetric power density of the core. This structure also helps inhibit horizontal movement of the second diffusion membrane 2 and prevents damage to the proton membrane 3 and the diffusion membrane. In this embodiment, the top surface of the second frame region 4b is higher than the top surface of the third frame region 4c, forming a clear dividing line. The outer end surface of the first diffusion membrane 1 is flush with this dividing line, facilitating positioning and installation. The asymmetric design of the first and second diffusion membranes 1 and 2 in this embodiment provides foolproofing, facilitating differentiation between process steps and improving production efficiency.

[0029] A support mechanism 61 is provided on both sides of each bipolar plate 6, and the support mechanism 61 is fitted to the upper side or lower side of the membrane electrode assembly. A sealing mechanism 62 is provided at the outer end of the support mechanism 61 for connecting to the fourth frame area 4d. Specifically, the thickness of the fourth frame area 4d is greater than the thickness of the third frame area 4c, so that the top surface and the bottom surface of the fourth frame area 4d are both raised relative to the top surface and the bottom surface of the third frame area 4c. The top surface and the bottom surface of the fourth frame area 4d are respectively fitted and connected to the sealing mechanism 62 to form a sealed installation. The specific structure of the sealing mechanism 62 is not limited. In this embodiment, the sealing mechanism may include three parts: a long strip portion and two small raised portions. The two small raised portions are arranged on the top surface and the bottom surface of the fourth frame area 4d of the support frame 4 for sealing a single fuel cell unit; a long strip portion is arranged between the two small raised portions for sealing two adjacent fuel cell units.

[0030] In this embodiment, the top surfaces of the first frame area 4a, the second frame area 4b, the third frame area 4c and the fourth frame area 4d have different horizontal heights, and the roughness of their surfaces is also different, which can be processed by laser, particle beam, etc. In this embodiment, it is preferred to use an ultraviolet laser processing method. The ultraviolet laser has a short wavelength and is a cold light source, which can effectively suppress the warping and deformation of the frame material caused by heat during the heating process. Compared with the frame manufactured by traditional resin injection molding, the processing method using ultraviolet laser is micro-machining, with short processing time and high production efficiency. The top surfaces of the first frame area 4a and the second frame area 4b as the contact ends can be set to a greater roughness to ensure installation stability.

[0031] During the ultraviolet laser processing, a laser thinning method is used. This method requires multiple scans of the top surface of the first frame area 4a. To ensure uniform flatness across the top surface of the frame area, it is preferred to adjust the scanning and filling angle, for example, by rotating each scanning and filling angle 90 degrees clockwise relative to the previous scanning and filling.

[0032] The above describes in detail the preferred embodiments of the present invention. It should be understood that those skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort. Therefore, any technical solutions that can be derived by those skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A membrane electrode assembly, comprising a first diffusion membrane (1), a second diffusion membrane (2) and a proton membrane (3), wherein the first diffusion membrane (1) and the second diffusion membrane (2) are arranged on the upper and lower sides of the proton membrane (3), characterized in that: The proton membrane (3) is also provided with a supporting frame (4), wherein the supporting frame (4) is a frame structure with a central hollow, and surrounds the four sides of the proton membrane (3); the supporting frame (4) is divided into a first frame area (4a), a second frame area (4b) and a third frame area (4c) from the inner circle to the outer circle, wherein the top surface of the second frame area (4b) is higher than the top surface of the third frame area (4c), and the top surface of the first frame area (4a) is lower than the top surface of the second frame area (4b) to form a mounting groove, wherein the four sides of the proton membrane (3) are fixed in the mounting groove; the first diffusion membrane (1) is installed on the upper side of the supporting frame (4), and the outer bottom of the first diffusion membrane (1) is in contact with the top of the second frame area (4b); the second diffusion membrane (2) is semi-submerged installed on the lower side of the supporting frame (4), and the second diffusion membrane (2) is semi-submerged installed in the hollow area of the supporting frame (4), and the outer end surface of the second diffusion membrane (2) is in contact with the inner end surface of the supporting frame (4); A glue layer (5) is provided between the first diffusion membrane (1) and the top surface of the second frame area (4b), and the glue layer (5) extends between the proton membrane (3) and the first diffusion membrane (1); A glue layer (5) is provided between the proton membrane (3) and the top surface of the first frame region (4a), and the glue layer (5) extends between the proton membrane (3) and the second diffusion membrane (2).

2. The membrane electrode assembly according to claim 1, characterized in that: The outer ring end surface of the first diffusion film (1) is flush with the boundary edge between the second frame area (4b) and the third frame area (4c).

3. The membrane electrode assembly according to claim 1, characterized in that: The top surfaces of the first frame area (4a) and the second frame area (4b) have a roughness higher than that of the top surface of the third frame area (4c).

4. A fuel cell stack core, characterized in that: The invention comprises a bipolar plate (6) and a membrane electrode assembly as claimed in any one of claims 1 to 3, wherein a plurality of bipolar plates (6) and a plurality of membrane electrode assemblies are stacked, and a support mechanism (61) is provided on both sides of the bipolar plate (6), and the support mechanism (61) is attached to the upper side or the lower side of the membrane electrode assembly.

5. A fuel cell stack core according to claim 4, characterized in that: Sealing mechanisms (62) are also provided on both sides of the bipolar plate (6), and the outer ring of the third frame area (4c) is further divided into a fourth frame area (4d). The sealing mechanism (62) is used to fit the top surface or bottom surface of the fourth frame area (4d).

6. A fuel cell stack core according to claim 5, characterized in that: The thickness of the third frame area (4c) is smaller than the thickness of the fourth frame area (4d), so that the top surface and the bottom surface of the fourth frame area (4d) are raised relative to the top surface and the bottom surface of the third frame area (4c).

7. A fuel cell stack core according to claim 4, characterized in that: Includes at least three membrane electrode assemblies.

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