Frame bonding method of proton exchange membrane and membrane electrode assembly

Abstract

The invention relates to a frame bonding method of a proton exchange membrane and a membrane electrode assembly, and belongs to the technical field of hydrogen fuel cells. The frame bonding method of the proton exchange membrane provided by the invention comprises the following steps: sequentially laminating a first resin membrane material, the proton exchange membrane and a second resin membrane material, flatly laying on a welding mold, and carrying out ultrasonic welding to complete frame bonding of the proton exchange membrane to obtain a membrane electrode assembly, the pressure of the ultrasonic welding is 0.15 to 0.6 MPa, and the welding time is 0.1 to 1 second. While bonding and sealing of the proton exchange membrane are achieved, the weather resistance and mechanical performance of the frame are remarkably improved, good mechanical performance is still kept after acid boiling, the performance of a fuel cell is comprehensively improved, and the service life of the fuel cell is prolonged.

Description

Technical Field

[0001] This invention relates to the field of hydrogen fuel cell technology, and in particular to a method for bonding the frame of a proton exchange membrane and a membrane electrode assembly. Background Technology

[0002] The membrane electrode assembly (MEA) is the most crucial component of a proton exchange membrane fuel cell. As a multi-layered structure, the MEA primarily consists of a proton exchange membrane, catalyst, gas diffusion layer, frame, and adhesive material for fixation. The frame plays a vital role in supporting the catalyst layer and positioning the fuel cell stack. The proton exchange membrane, a semi-permeable membrane mainly composed of ionomers, is designed to conduct protons while simultaneously acting as an electron insulator and reactant barrier.

[0003] In existing membrane electrode assembly (MEA) products, the frame and proton exchange membrane are typically bonded together using a hot press under specific temperature and pressure conditions. This hot-pressing process involves stacking the adhesive-coated frame and proton exchange membrane according to a defined structure, flattening them, and then pressing them together under specific temperature and pressure conditions in a flatbed hot press. This process is performed manually offline, resulting in long preparation times, multiple material transfers, and difficulty in achieving continuous production automation, posing a significant obstacle to the construction of continuous production lines. Furthermore, the materials require bonding with a hot-melt adhesive layer, which carries the risk of adhesive material leaching, affecting MEA performance. Additionally, the bonded interface formed by the hot-pressing process exhibits decreased mechanical properties after acid treatment, and the product's operating environment poses a risk of damaging the seal of the frame and proton exchange membrane. This ultimately impacts the performance and lifespan of the fuel cell.

[0004] Therefore, there is an urgent need to develop a method for fixing and bonding proton exchange membrane frames that can eliminate the need for an adhesive layer and improve the mechanical properties of the bonding interface. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a method for bonding the frame of a proton exchange membrane and a membrane electrode assembly. The bonding method provided by this invention uses a resin without an adhesive layer as the frame material, significantly improving the mechanical properties and acid resistance of the frame, thereby comprehensively improving the performance of the fuel cell.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a method for bonding the frame of a proton exchange membrane, comprising the following steps: The first resin membrane material, the proton exchange membrane, and the second resin membrane material are sequentially stacked and laid flat on a welding mold. Ultrasonic welding is then performed to complete the bonding of the proton exchange membrane frame, resulting in a membrane electrode assembly. The ultrasonic welding pressure is 0.15-0.6 MPa, and the welding time is 0.1-1 s.

[0007] The proton exchange membrane frame bonding method of the present invention mainly adopts ultrasonic welding process to achieve bonding of the membrane material without adhesive layer and the proton exchange membrane, so as to achieve good sealing between the proton membrane and the frame material and improve the quality and performance of the membrane electrode product.

[0008] The ultrasonic welding process used in this invention utilizes an ultrasonic generator to convert current into high-frequency electrical energy, which is then converted into mechanical vibration of the same frequency by a transducer. The amplitude is then changed by an amplitude modulator and a welding head and applied directly to the frame material. The high-frequency vibration drives the frame and proton exchange membrane material to rub against each other, generating heat that is transferred to the welding interface. This causes the contact surface between the frame and the proton exchange membrane to melt and fuse, achieving a sealing bond without the need for an adhesive layer.

[0009] The membrane electrode assembly prepared by the method of the present invention provides the frame with good mechanical properties, high peel force and shear force without the use of hot melt adhesive, and can stably maintain the original peel performance after acid boiling, achieving stable sealing and bonding. This overcomes the defects of traditional bonding and curing processes and is conducive to further improving the performance and life of fuel cells.

[0010] Preferably, the ultrasonic welding pressure is 0.15-0.6 MPa, for example, it can be one or any two of the following: 0.15 MPa, 0.20 MPa, 0.25 MPa, 0.30 MPa, 0.35 MPa, 0.40 MPa, 0.45 MPa, 0.50 MPa, 0.55 MPa, and 0.60 MPa.

[0011] Preferably, the ultrasonic welding time is 0.1-1s, for example, it can be one or any two of the following: 0.1s, 0.2s, 0.3s, 0.4s, 0.5s, 0.6s, 0.7s, 0.8s, 0.9s, and 1.0s.

[0012] Preferably, the mold is one of the following: a flat mold, a mesh mold, a diamond-shaped mold, a serrated mold, or a fabric-patterned mold.

[0013] More preferably, the mold is a diamond-shaped mold or a serrated mold.

[0014] Preferably, the width of the mold is 5-20mm.

[0015] The bonding method provided by this invention can be designed with special welding head fixtures and welding base plates according to the different shape requirements of the product, which can more accurately control the welding surface. By controlling the texture of the mold, the bonding effect can be further optimized, and different welding areas can be achieved by adjusting the width.

[0016] Preferably, the first resin film material and the second resin film material each independently include at least one of polyphenylene sulfide (PPS), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide (PI), polypropylene (PP), and polyethylene (PE).

[0017] More preferably, both the first resin film material and the second resin film material are PPS.

[0018] Preferably, the ultrasonic frequency of the ultrasonic welding is 15-40kHz, for example, it can be one or any two of 15kHz, 20kHz, 25kHz, 30kHz, 35kHz, and 40kHz.

[0019] Preferably, the ultrasonic welding amplitude is 36-48μm, for example, it can be one or any two of the following values: 36μm, 37μm, 38μm, 39μm, 40μm, 41μm, 42μm, 43μm, 44μm, 45μm, 46μm, 47μm, and 48μm.

[0020] Preferably, the ultrasonic welding pressure is 0.2-0.6 MPa.

[0021] More preferably, the ultrasonic welding pressure is 0.5-0.6 MPa.

[0022] Preferably, the ultrasonic welding time is 0.35-6s.

[0023] In ultrasonic welding, by precisely adjusting the matching relationship of the three core parameters—amplitude, pressure, and welding time—it is possible to ensure that the frame material and the proton exchange membrane form a stable fusion interface, while avoiding penetrating damage to the structural integrity of the frame and the functional characteristics of the proton exchange membrane caused by parameter imbalance.

[0024] If the amplitude is too low, it will not be enough to melt the frame resin, resulting in only a superficial weld that is prone to detachment during use. If the amplitude is too high, it will cause excessive concentration of local vibration energy, potentially leading to overheating of the proton exchange membrane or frame resin and deterioration of its mechanical properties. If the pressure is too low, it will result in insufficient fusion and poor mechanical properties; if the pressure is too high, it may cause severe deformation, affecting the sealing performance. If the welding time is too short, the frame resin will not form a sufficiently deep interfacial diffusion, resulting in weak interfacial bonding after welding; if the welding time is too long, the frame resin may over-melt, causing overflow and significantly affecting the actual frame bonding effect.

[0025] Preferably, the first resin membrane material and the second resin membrane material each have a primer layer independently provided on the side facing the proton exchange membrane.

[0026] Applying a primer layer to the side of the frame material facing the proton exchange membrane can regulate interfacial compatibility and optimize welding performance.

[0027] More preferably, the primer layer includes at least one of acrylate, polyurethane, and silicone.

[0028] Secondly, the present invention provides a membrane electrode assembly obtained by the above-described proton exchange membrane frame bonding method.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) No hot melt adhesive layer required: The proton exchange membrane frame bonding method provided by the present invention does not require hot melt adhesive to assist welding, and will not cause unnecessary material precipitation, reducing additional impact on the electrical performance of the product. (2) Improved mechanical properties: The membrane electrode assembly prepared by the proton exchange membrane frame bonding method provided in this invention did not show significant changes in the mechanical properties of the bonding interface after 1500h acid boiling. (3) Controllable welding interface: The proton exchange membrane frame bonding method provided by the present invention can precisely adjust the bonding interface by adjusting the interface location of ultrasonic vibration through precise parameter setting of the welding equipment.

[0030] (4) Continuous production is possible: The welding time of the proton exchange membrane frame bonding method provided by the present invention is very short. Ultrasonic welding equipment can be directly installed on the automatic production line to achieve continuous production, which is highly feasible. Detailed Implementation

[0031] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments. Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods; the materials and reagents used, unless otherwise specified, are commercially available reagents and materials.

[0032] The PPS film material used in the following examples and comparative examples is: Toray standard grade PPS film, Torelina 3000; the ultrasonic welding equipment used in the following examples and comparative examples is: Suzhou Mingsen 20kHz servo ultrasonic plastic welding machine, SH-20DDS-3000.

[0033] Example 1 An embodiment of the proton exchange membrane frame bonding method and membrane electrode assembly of the present invention is described below: S1. Lay out PPS membrane material-proton exchange membrane-PPS membrane material in a sandwich structure; the side of PPS membrane material facing the proton exchange membrane is first coated with an acrylic primer layer. S2. Place the stacked samples on the mold of the welding base. The mold is a mold with a serrated pattern. The mold material is magnesium-aluminum alloy and the width is 10mm. S3. Using a 20kHz ultrasonic welding device, set the parameters as follows: welding amplitude of 80% (reference amplitude of 60μm, actual amplitude of 48μm), welding pressure of 0.5MPa, and welding time of 0.35s. Then perform the welding operation to complete the bonding of the proton exchange membrane frame and obtain the membrane electrode assembly.

[0034] Examples 2-4 and Comparative Examples 1-4 The specific differences between the bonding methods of Examples 2-4 and Comparative Examples 1-4 and Example 1 are shown in Table 1.

[0035] Table 1 Example of effect To investigate the mechanical properties and weather resistance of the membrane electrode assembly obtained by the proton exchange membrane frame bonding method provided in this invention, the following tests were conducted: (1) Cut the sample obtained after ultrasonic welding into strips with a width of 2cm, and use a universal testing machine to test the peel force, shear force and separation test between the frame and the proton membrane to characterize the welding performance of ultrasonic welding process.

[0036] (2) Immerse some of the samples in a 0.05 mol / L sulfuric acid solution, place them in an oven at 90°C for 1500 h, take out the samples, wash them with water to remove the acid solution, and use a universal testing machine to perform peel and shear tests.

[0037] The test results are shown in Table 2.

[0038] Table 2 As shown in Table 2: The proton exchange membrane frame bonding method provided by this invention ensures a stable fusion interface between the frame material and the proton exchange membrane by precisely adjusting the matching relationship of three core parameters: amplitude, pressure, and welding time. This avoids penetrating damage to the structural integrity of the frame and the functional characteristics of the proton exchange membrane. The resulting membrane electrode assembly exhibits excellent mechanical properties, with a peel force exceeding 11N and a shear force exceeding 39N, both significantly higher than the comparative example. Furthermore, after a 1500-hour acid boiling test, the mechanical properties remain essentially unchanged, demonstrating good weather resistance. This comprehensively improves the performance and extends the lifespan of the fuel cell. In contrast, the imbalance of parameters in the ultrasonic welding of the comparative example leads to poor welding results or damage to the structural integrity of the frame or the functional characteristics of the proton exchange membrane, resulting in overall performance degradation.

[0039] In summary, the proton exchange membrane frame bonding method provided by this invention does not require hot melt adhesive for welding, avoids unnecessary substance precipitation, and reduces additional impact on the product's electrical performance. After acid boiling, the mechanical properties of the bonding interface of the fabricated membrane electrode assembly do not change significantly; in fact, the mechanical properties are improved. Furthermore, the bonding interface can be precisely adjusted by controlling the interface location of ultrasonic vibration through precise parameter settings of the welding equipment. Simultaneously, the welding time is very short, allowing the ultrasonic welding equipment to be directly installed on automated production lines for continuous production. Performance testing has verified the feasibility of the method and demonstrated its high application value.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for bonding the frame of a proton exchange membrane, characterized in that, Includes the following steps: The first resin membrane material, the proton exchange membrane, and the second resin membrane material are sequentially stacked and laid flat on a welding mold. Ultrasonic welding is then performed to complete the bonding of the proton exchange membrane frame, resulting in a membrane electrode assembly. The ultrasonic welding pressure is 0.15-0.6 MPa, and the welding time is 0.1-1 s.

2. The method for bonding the frame of a proton exchange membrane as described in claim 1, characterized in that, The mold is one of the following: flat mold, mesh mold, diamond mold, serrated mold, or fabric mold.

3. The method for bonding the frame of a proton exchange membrane as described in claim 1, characterized in that, The width of the mold is 5-20mm.

4. The method for bonding the frame of a proton exchange membrane as described in claim 1, characterized in that, The first resin film material and the second resin film material each independently include at least one of polyphenylene sulfide, polyethylene terephthalate, polyethylene naphthalate, polyimide, polypropylene, and polyethylene.

5. The method for bonding the frame of a proton exchange membrane as described in claim 1, characterized in that, The ultrasonic welding frequency is 15-40kHz.

6. The method for bonding the frame of a proton exchange membrane as described in claim 1, characterized in that, The ultrasonic welding amplitude is 36-48 μm.

7. The method for bonding the frame of a proton exchange membrane as described in claim 1, characterized in that, The ultrasonic welding pressure is 0.2-0.6 MPa.

8. The method for bonding the frame of a proton exchange membrane as described in claim 1, characterized in that, Each of the first resin membrane material and the second resin membrane material has a primer layer independently provided on the side facing the proton exchange membrane.

9. The method for bonding the frame of a proton exchange membrane as described in claim 8, characterized in that, The primer layer includes at least one of acrylate, polyurethane, and silicone.

10. A membrane electrode assembly obtained by the frame bonding method of a proton exchange membrane as described in any one of claims 1-9.

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