A membrane electrode packaging structure and packaging method

Abstract

The present invention relates to the field of fuel cells, and more specifically, to a membrane electrode packaging structure and packaging method. This membrane electrode packaging structure comprises a top gas diffusion layer and a bottom gas diffusion layer, with a stacked frame and catalyst-coated membrane sandwiched between the two gas diffusion layers. The catalyst-coated membrane is bonded to the top surface of the frame. There is only one frame, and the top surface of the frame has a recessed area for the catalyst-coated membrane to adhere to. The catalyst-coated membrane is bonded to the bottom wall of the recess, and the inner sidewall of the recess seals the catalyst-coated membrane. This packaging structure can reduce production costs and minimize the risk of air leakage in the sealed area.

Description

Technical Field

[0001] The present invention relates to the field of fuel cells, and in particular to a membrane electrode packaging structure and a packaging method. Background Art

[0002] like Figure 1 The current mainstream packaging method for membrane electrodes is as follows: first, the anode catalyst layer and the cathode catalyst layer are coated on the two end surfaces of the proton exchange membrane respectively to prepare a catalyst coated membrane 4 (CCM) with a three-layer structure; then the edges of the catalyst coated membrane 4 are bonded and sealed with the edges of the two frames 1 and 9 by adhesive to form a five-layer component; finally, the two gas diffusion layers 5 and 6 are bonded to the frames respectively by adhesive to form a seven-layer membrane electrode.

[0003] Although the above double-layer frame membrane electrode can meet the basic sealing requirements, it has the following two major disadvantages in large-scale batch production:

[0004] (1) High cost:

[0005] Because it is a double-layer frame structure, the amount of frame materials and adhesives used is large, and the cost is high for large-scale mass production. In particular, since the working environment of fuel cells involves harsh conditions such as high and low humidity cycles, high and low temperature cycles, and strong chemical corrosion (free radicals), special-purpose adhesives are required. The research and development and production costs of such adhesives are high. Therefore, if the amount of adhesive used is large, the cost will be very high.

[0006] (2) High difficulty in quality control:

[0007] ① When pre-coating glue on the frame, unevenness may occur. For example, there may be defects such as no glue or insufficient glue in some areas. It is very easy for the gas on one side of the catalyst coating membrane to break through the sealing structure formed by the adhesive layer and leak to the other side of the catalyst coating membrane, causing leakage and affecting performance.

[0008] ② If Figure 2 After pre-coating, when the two frames 1 and 9 and the catalyst-coated membrane 4 are pressed together, uneven pressing force may occur, resulting in defects. For example, bubbles 10 in the first adhesive 3 may cause gas on one side of the catalyst-coated membrane 4 to leak through the bubbles 10 in the first adhesive 3 to the other side of the catalyst-coated membrane, causing leakage. Although improved pressing methods, such as using rollers instead of flat presses and pre-vacuuming, can alleviate defects such as bubbles to a certain extent, completely solving the bubble problem remains difficult, and pre-vacuuming is time-consuming and reduces production efficiency.

[0009] ③ When the two frames 1 and 9 and the catalyst coating film 4 are pressed together after pre-coating, deformation and displacement are likely to occur, making it impossible to accurately align them. Summary of the Invention

[0010] The present invention provides a membrane electrode packaging structure and a packaging method. The packaging structure can reduce production costs and has a low risk of gas leakage.

[0011] In order to reduce the amount of frame and adhesive used, the inventor designed a membrane electrode packaging structure with a single-layer frame. The exploded diagram of the membrane electrode packaging structure with a single-layer frame is shown in FIG. Figure 3 As shown, it includes a top gas diffusion layer 5, a catalyst coating membrane 4, a frame 1 and a bottom gas diffusion layer 6 arranged in sequence. Compared with the traditional double-layer frame membrane electrode packaging structure, although this structure uses only one layer of frame 1, it not only reduces the amount of frame material, but also significantly reduces the amount of adhesive used due to the reduction in the number of bonding layers, thereby reducing costs. However, the inventors found that since only one side of the catalyst coating membrane 4 is bonded to the frame 1, during the assembly and operation of the fuel cell, the catalyst coating membrane 4 will be displaced due to external mechanical forces and internal swelling tension caused by dry-wet cycles, thereby causing the first adhesive 3 (see Figure 4 ) The sealing structure formed leaks and the stack fails. Figure 4 As shown, the packaging structure generates higher mechanical stress in the overlapping area of ​​the top surface gas diffusion layer 5-catalyst coating membrane 4-frame 1 than in the surrounding area (the stress direction is as shown in FIG. Figure 4 (as indicated by the arrow in the middle), which will lead to: (1) mechanical degradation of the edge of the proton exchange membrane in the catalyst coated membrane 4; (2) the catalyst coated membrane 4 falls off from the frame 1; (3) the top surface gas diffusion layer 5 causes physical damage to the catalyst coated membrane 4. The above three situations will eventually lead to the failure of the membrane electrode seal, thereby causing gas leakage.

[0012] In order to achieve the above object, the present invention adopts the following technical solutions:

[0013] A membrane electrode packaging structure includes a top gas diffusion layer and a bottom gas diffusion layer. A stacked frame and a catalyst-coated membrane are sandwiched between the two gas diffusion layers. The catalyst-coated membrane is bonded and fixed to the top surface of the frame. There is only one frame. The top surface of the frame is recessed at the site for bonding the catalyst-coated membrane. The catalyst-coated membrane is bonded to the bottom wall of the recess, and the inner sidewall of the recess blocks the periphery of the catalyst-coated membrane.

[0014] Furthermore, the inner sidewall of the recess abuts against the side surface of the catalyst-coated membrane to prevent the catalyst-coated membrane from being laterally shifted and dislocated.

[0015] Furthermore, the bottom wall surface of the depression is rough.

[0016] Furthermore, the catalyst coating membrane is bonded to the bottom wall of the depression through a first adhesive layer, and the top gas diffusion layer is bonded to the non-depression of the top surface of the frame through a second adhesive layer and covers the top surface of the catalyst coating membrane. The sum of the thickness values ​​of the inner wall of the depression and the second adhesive layer is not less than the sum of the thickness values ​​of the first adhesive layer and the catalyst coating membrane, so that the top gas diffusion layer is bonded to the frame as a whole and flat, and the bottom gas diffusion layer is bonded to the bottom surface of the frame.

[0017] Furthermore, the sum of the thicknesses of the inner sidewall of the recess and the second adhesive layer is equal to the sum of the thicknesses of the first adhesive layer and the catalyst coating film.

[0018] A membrane electrode packaging method comprises the following steps:

[0019] Concave construction step: using only one frame, constructing a concave on the top surface of the frame for the catalyst coating film to sink into and adhere to;

[0020] The catalyst coating film bonding step includes placing the catalyst coating film in an area surrounded by the inner sidewall of the recess, so that the bottom surface of the catalyst coating film is bonded to the bottom wall of the recess, and the inner sidewall of the recess blocks the periphery of the catalyst coating film;

[0021] Gas diffusion layer bonding steps: bonding the top gas diffusion layer to the non-recessed area of ​​the top surface of the frame so that the top gas diffusion layer covers the top surface of the catalyst coated membrane; bonding the bottom gas diffusion layer to the bottom surface of the frame so that the bottom gas diffusion layer covers the bottom surface of the catalyst coated membrane.

[0022] Furthermore, in the recess construction step, specifically: the area enclosed by the inner sidewall of the recess is the same shape and size as the catalyst coating membrane, so that the inner sidewall of the recess presses against the side of the catalyst coating membrane to prevent the catalyst coating membrane from lateral displacement.

[0023] Furthermore, the top gas diffusion layer is bonded to the non-recessed portion of the top surface of the frame through a second adhesive layer, and the bottom gas diffusion layer is bonded to the bottom surface of the frame through a third adhesive layer. The sum of the thicknesses of the inner side wall of the recess and the second adhesive layer is not less than the sum of the thicknesses of the first adhesive layer and the catalyst coating membrane, so that the top gas diffusion layer is bonded to the frame as a whole and flat.

[0024] Furthermore, the sum of the thicknesses of the inner sidewall of the recess and the second adhesive layer is equal to the sum of the thicknesses of the first adhesive layer and the catalyst coating film.

[0025] Furthermore, in the recess forming step, the tool system etches the top surface of the frame to form the recess.

[0026] Beneficial effects: Since there is only one frame to bond the catalyst coated membrane, frame materials and adhesive materials are saved, saving costs; the inner side wall of the recess blocks the periphery of the catalyst coated membrane, which, on the one hand, can prevent the catalyst coated membrane and the frame from being misaligned during production and use, facilitates production, and reduces the problem of air leakage caused by misalignment; on the other hand, even if defects such as bubbles are formed at the bonding point between the catalyst coated membrane and the frame during assembly and pressing, the gas on one end face of the catalyst coated membrane reaches the side face of the catalyst coated membrane through defects such as bubbles, and will be blocked by the inner side wall of the recess and cannot leak to the other end face, thereby reducing the possibility of air leakage. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is an exploded view of the membrane electrode structure with a double-layer frame;

[0028] Figure 2 This is a structural diagram of the frame and catalyst coating membrane in the double-layer frame membrane electrode structure;

[0029] Figure 3 It is an exploded diagram of the membrane electrode structure with a single-layer frame;

[0030] Figure 4 This is the packaging structure diagram of a single-layer frame film electrode made by traditional packaging method;

[0031] Figure 5 This is a schematic diagram of the packaging process of the single-layer frame film electrode of this embodiment;

[0032] Figure 6 It is the main view after the depression is formed on the frame;

[0033] Figure 7 This is a packaging structure diagram of the single-layer frame film electrode of this embodiment. DETAILED DESCRIPTION

[0034] The specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0035] like Figure 5 , the membrane electrode packaging method comprises the following steps:

[0036] ① Only one frame 1 is used, and a recess 2 is constructed by surface plasma etching or laser etching on the top surface of the frame 1. The area surrounded by the inner sidewall 21 of the recess 2 (such as Figure 6 The area enclosed by the dotted line) is the same shape and size as the catalyst coating film 4, and the thickness of the inner side wall 21 of the recess 2 is equal to the thickness of the catalyst coating film 4;

[0037] ② Apply a layer of first adhesive 3 with a thickness of 3 to 20 microns on the bottom wall 22 of the recess 2, so that the first adhesive 3 contacts the inner side wall 21 of the recess 2;

[0038] ③ The catalyst coating film 4 is placed in the area enclosed by the inner sidewall 21 of the recess 2. The inner sidewall 21 of the recess 2 abuts against the periphery of the catalyst coating film 4, thereby sealing the periphery of the catalyst coating film 4 and preventing the catalyst coating film 4 from lateral displacement. The first adhesive 3 is then cured by heat curing, light curing, or pressure curing, depending on the type of the first adhesive 3, to form an adhesive layer 3, thereby bonding the bottom surface of the catalyst coating film 4 to the bottom wall 22 of the recess 2.

[0039] ④ A layer of second adhesive 7 having the same thickness as that of the first adhesive 3 is applied to the non-recessed portion 11 of the top surface of the frame 1, and the top gas diffusion layer 5 is bonded to the non-recessed portion 11 of the top surface of the frame 1 via the second adhesive 7. Since the sum of the thicknesses of the inner sidewall 21 of the recess 2 and the second adhesive layer 7 is equal to the sum of the thicknesses of the first adhesive layer 3 and the catalyst-coated membrane 4, that is, the second adhesive layer 7 is flush with the upper surface of the catalyst-coated membrane 4, the top gas diffusion layer 5 is bonded flatly to the frame 1 as a whole and contacts the top surface of the catalyst-coated membrane 4, that is, covers the top surface of the catalyst-coated membrane 4;

[0040] ⑤ Apply a layer of third adhesive 8 on the bottom surface of the frame 1, and adhere the bottom gas diffusion layer 6 to the bottom surface of the frame 1 through the third adhesive 8 layer, so that the bottom gas diffusion layer 6 covers the bottom surface of the catalyst coated membrane 4.

[0041] After the membrane electrode packaging is completed, Figure 7 The first adhesive layer 3 bonds the bottom wall 22 of the depression 2 and the lower surface edge of the catalyst coated membrane 4 to form a first barrier, which prevents the air below the catalyst coated membrane 4 from leaking to the top of the catalyst coated membrane 4. Moreover, since the surface of the bottom wall 22 of the depression 2 obtained by etching is rough, the first adhesive 3 has a strong bonding force with the bottom wall 22 of the depression 2 and is not easy to fall off from the bottom wall 22 of the depression 2, thereby reducing the possibility of gas leakage from the bonding point between the first adhesive 3 and the bottom wall 22 of the depression 2; the inner side wall 21 of the depression 2 presses against the side of the catalyst coated membrane 4, thereby blocking the surrounding of the catalyst coated membrane 4 to form a second barrier, so that even if there are gas channels or bubbles in the first barrier (i.e., the first adhesive layer 3), the gas below the catalyst coated membrane 4 will be blocked by the second barrier (i.e., the inner side wall 21 of the depression 2) after breaking through the first barrier, thereby preventing leakage. The sum of the thickness of the inner side wall 21 of the recess 2 and the second adhesive 7 layer is equal to the sum of the thickness of the first adhesive 3 layer and the catalyst coating membrane 4, that is, the second adhesive layer 7 and the upper surface of the catalyst coating membrane 4 are flush, so the top gas diffusion layer 5 is flatly bonded to the frame 1, and the overlapping area of ​​the top gas diffusion layer 5-catalyst coating membrane 4-frame 1 is subjected to the same stress as other surrounding areas (the stress direction is as follows: Figure 7 ), so it will not appear Figure 4 The uneven stress problem caused by the structure will not cause air leakage.

[0042] Not preferably, the thickness of the inner wall 21 at the groove 2 may not be equal to but greater than the thickness of the catalyst coated membrane 4. In this case, the top gas diffusion layer 5 remains overall flat under the support of the second adhesive layer 7, and there will be no uneven stress. It just does not contact the catalyst coated membrane 4.

[0043] Not preferably, a fourth adhesive layer is provided between the inner sidewall 21 of the groove 2 and the side surface of the catalyst-coated membrane 4, thereby making it more difficult for gas below the catalyst-coated membrane 4 to leak to above the catalyst-coated membrane 4. Although this packaging structure has better anti-leakage performance, the use of an additional layer of a fourth adhesive increases costs and is therefore not a preferred method.

[0044] The above description is only a preferred embodiment of the present invention. The present invention is not limited to the above embodiment. There may be local minor structural changes during implementation. If various changes or modifications of the present invention do not depart from the spirit and scope of the present invention and fall within the scope of the claims of the present invention and equivalent technologies, the present invention is also intended to include these changes and modifications.

Claims

1. A membrane electrode package structure, comprising a top gas diffusion layer and a bottom gas diffusion layer, wherein a frame and a catalyst coating membrane are stacked between the two gas diffusion layers, and the catalyst coating membrane is bonded and fixed to the top surface of the frame, wherein the frame There is only one, the top surface of the frame is recessed at a location where the catalyst coating film is bonded, the catalyst coating film is bonded to the bottom wall of the recess, and the inner side wall of the recess seals the periphery of the catalyst coating film; The catalyst coating membrane is bonded to the bottom wall of the depression through a first adhesive layer, the thickness of the first adhesive layer on the bottom wall of the depression is 3~20μm, the top gas diffusion layer is bonded to the non-depression of the top surface of the frame through a second adhesive layer and covers the top surface of the catalyst coating membrane, the sum of the thickness values ​​of the inner wall of the depression and the second adhesive layer is not less than the sum of the thickness values ​​of the first adhesive layer and the catalyst coating membrane, so that the top gas diffusion layer is bonded to the frame as a whole and flat, and the bottom gas diffusion layer is bonded to the bottom surface of the frame.

2. The membrane electrode package structure according to claim 1, characterized in that: The inner sidewall of the recess abuts against the side of the catalyst-coated membrane to prevent the catalyst-coated membrane from being laterally shifted and dislocated.

3. The membrane electrode package structure according to claim 1, characterized in that: The bottom wall surface of the depression is rough.

4. The membrane electrode package structure according to claim 1, characterized in that: The sum of the thicknesses of the inner sidewall of the recess and the second adhesive layer is equal to the sum of the thicknesses of the first adhesive layer and the catalyst coating film.

5. A membrane electrode packaging method for preparing the membrane electrode packaging structure according to any one of claims 1 to 4, characterized in that: The following steps are involved: Concave construction step: using only one frame, constructing a concave on the top surface of the frame for the catalyst coating film to sink into and adhere to; The catalyst coating film bonding step includes placing the catalyst coating film in an area surrounded by the inner sidewall of the recess, so that the bottom surface of the catalyst coating film is bonded to the bottom wall of the recess, and the inner sidewall of the recess blocks the periphery of the catalyst coating film; Gas diffusion layer bonding step: bonding the top gas diffusion layer to the non-depressed area of ​​the top surface of the frame so that the top gas diffusion layer covers the top surface of the catalyst coated membrane; bonding the bottom gas diffusion layer to the bottom surface of the frame so that the bottom gas diffusion layer covers the bottom surface of the catalyst coated membrane.

6. The membrane electrode packaging method according to claim 5, characterized in that: In the recess construction step, specifically: the area enclosed by the inner sidewall of the recess is the same shape and size as the catalyst coating membrane, so that the inner sidewall of the recess abuts against the side of the catalyst coating membrane to prevent the catalyst coating membrane from lateral displacement.

7. The membrane electrode packaging method according to claim 5, characterized in that: The top gas diffusion layer is bonded to the non-recessed portion of the top surface of the frame through a second adhesive layer, and the bottom gas diffusion layer is bonded to the bottom surface of the frame through a third adhesive layer. The sum of the thicknesses of the inner side wall of the recess and the second adhesive layer is not less than the sum of the thicknesses of the first adhesive layer and the catalyst coating membrane, so that the top gas diffusion layer is bonded to the frame as a whole and flat.

8. The membrane electrode packaging method according to claim 7, characterized in that: The sum of the thicknesses of the inner sidewall of the recess and the second adhesive layer is equal to the sum of the thicknesses of the first adhesive layer and the catalyst coating film.

9. The membrane electrode packaging method according to claim 5, characterized in that: In the recess construction step, the recess is specifically constructed by etching the top surface of the frame.

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