A method for preparing a membrane electrode by one-step two-stage hot press transfer and a membrane electrode
By using a one-step, two-stage hot-pressing transfer method, the problem of uneven catalyst transfer was solved, achieving complete transfer of the catalyst layer and improving the performance of the membrane electrode, thereby increasing the yield and peak power density of the membrane electrode.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANGHAI INST OF SPACE POWER SOURCES
- Filing Date
- 2024-12-11
- Publication Date
- 2026-07-03
AI Technical Summary
In the preparation of membrane electrodes for proton exchange membrane fuel cells using the existing thermal transfer method, it is difficult to control the catalyst adhesion strength and the transfer is uneven, resulting in low yield and the inability to reuse the transfer substrate, which affects the performance and lifespan of the membrane electrode.
The method employs a one-step, two-stage hot-press transfer process. First, a relatively long low-pressure heat treatment is performed to flatten the proton exchange membrane and soften and melt the catalyst layer. Then, a shorter high-pressure heat treatment is performed to ensure close contact between the catalyst layer and the proton exchange membrane. Finally, the transfer substrate is removed and the edges are sealed to form the final product.
Achieving 100% transfer rate of the catalyst layer improved the yield and peak power density of the membrane electrode, reduced mass transfer impedance, and extended the service life of the membrane electrode.
Smart Images
Figure CN119812412B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of fuel cell technology, specifically relating to a method for preparing membrane electrodes using a one-step two-stage hot-pressing transfer method and the membrane electrode itself. Background Technology
[0002] When fabricating membrane electrode assemblies (MEAs) for proton exchange membrane fuel cells using the thermal transfer method, the catalyst layer needs to be transferred onto the proton exchange membrane via a transfer substrate, and then the transfer substrate is removed to obtain the catalyst-coated membrane. However, practical applications have revealed the following shortcomings of this method: the adhesion strength of the catalyst on the proton exchange membrane is uncontrollable due to the influence of temperature and pressure; and during hot pressing, the catalyst on the edge between the membrane and the transfer substrate cannot be completely transferred to the proton exchange membrane due to uneven stress, thus reducing the yield of the MEA; furthermore, the transfer substrate often deforms due to hot pressing and cannot be reused, increasing the manufacturing cost of the MEA.
[0003] In recent years, with the continuous research and development of researchers, a thermal transfer method for preparing membrane electrodes has been disclosed, which combines ultrasonic spraying and thermal transfer processes. However, the following problems still exist: the method includes ultrasonic spraying, which is time-consuming, and the platinum loading distribution of the membrane electrodes prepared by this method is not uniform, which seriously affects the performance and lifespan of the membrane electrodes.
[0004] Therefore, developing a novel thermal transfer method for preparing membrane electrodes to improve the catalytic layer transfer rate, increase the yield and lifespan of the membrane electrodes is an urgent problem to be solved in this field. Summary of the Invention
[0005] The purpose of this invention is to provide a novel method for preparing membrane electrodes by hot pressing transfer printing, so as to improve the transfer rate of the catalyst layer, thereby improving the yield and service life of the membrane electrode.
[0006] To achieve the above objectives, the present invention first provides a method for preparing a membrane electrode by one-step two-stage hot-press transfer printing, comprising the following steps:
[0007] S1, the cathode catalyst slurry is coated onto the first transfer substrate to form a cathode catalyst layer, and the anode catalyst slurry is coated onto the second transfer substrate to form an anode catalyst layer;
[0008] S2, the first flat layer, the second transfer substrate with the anode catalyst layer, the proton exchange membrane, the first transfer substrate with the cathode catalyst layer and the second flat layer are sequentially stacked and laid flat on a hot press, and the first hot pressing treatment and the second hot pressing treatment are sequentially performed, with the cathode catalyst layer and the anode catalyst layer disposed close to the proton exchange membrane;
[0009] Wherein, the processing pressure of the first hot pressing is less than the processing pressure of the second hot pressing, and the processing time of the first hot pressing is greater than or equal to the processing time of the second hot pressing.
[0010] Preferably, the processing pressure of the first hot pressing treatment is 1 kg / cm². 2 -10kg / cm 2 The processing temperature is 120℃-170℃; the processing time is 60 seconds-300 seconds.
[0011] Preferably, the processing pressure of the second hot pressing treatment is 10 kg / cm². 2 -80kg / cm 2 The processing temperature is 120℃-170℃; the processing time is 10 seconds-60 seconds.
[0012] Preferably, the first and second ply layers are made of porous materials, including any one of carbon paper, carbon cloth, high-temperature paper, or thin steel plate.
[0013] Preferably, the area of the first and second planar layers is greater than or equal to the area of the proton exchange membrane.
[0014] Preferably, the thickness of the first and second tiling layers is 10 μm to 300 μm.
[0015] Preferably, the thickness of the proton exchange membrane is 40 μm to 160 μm.
[0016] Preferably, in step S1, a slot coating method is used to coat the cathode catalyst slurry and the anode catalyst slurry onto the first transfer substrate and the second transfer substrate, respectively.
[0017] Preferably, the process further includes: S3, removing the first and second transfer substrates from the product of step S2, attaching carbon paper to both sides, sealing the frame, and stamping to form a membrane electrode.
[0018] In another aspect, the present invention provides a membrane electrode assembly, wherein the membrane electrode is prepared by the aforementioned method.
[0019] Compared with the prior art, the beneficial effects of the present invention include at least the following:
[0020] This invention provides a method for preparing a film electrode by one-step two-stage hot pressing transfer, comprising: a first hot pressing treatment stage and a second hot pressing treatment stage.
[0021] The first hot-pressing stage is a relatively long low-pressure heat treatment process. In this stage, the prolonged heat and low pressure flatten the proton exchange membrane. Simultaneously, the extended heat softens and melts the cathode and anode catalyst layers, increasing their fluidity. Combined with the low pressure, this allows the cathode and anode catalyst layers to form an initial tight contact with the proton exchange membrane. This not only compensates for the potential insufficient material contact tightness caused by the shortened high-pressure heat treatment time, but more importantly, the tight contact between the cathode and anode catalyst layers and the proton exchange membrane is a conformal, close fit with no gaps at the interface. This significantly improves the transfer rate of the cathode and anode catalyst layers onto the proton exchange membrane, achieving a transfer rate of up to 100%.
[0022] The second hot-pressing stage is a short-duration high-pressure heat treatment process. This stage reduces the high-pressure treatment time on the cathode and anode catalyst layers, preserving the initial pore structure of the cathode and anode catalyst layers to the greatest extent, reducing the mass transfer impedance of the membrane electrode, and enabling the membrane electrode prepared by the method of this invention to have a higher peak power density. Attached Figure Description
[0023] Figure 1 This is a flowchart of the method for preparing a membrane electrode by one-step two-stage hot pressing transfer printing according to the present invention.
[0024] Figure 2 This is a photograph of the membrane electrode prepared in Example 1.
[0025] Figure 3 This is a photograph of the membrane electrode prepared in Example 2.
[0026] Figure 4 This is a photograph of the membrane electrode prepared in Example 3.
[0027] Figure 5 This is a photograph of the membrane electrode prepared in Comparative Example 1.
[0028] Figure 6 The thickness of the membrane electrodes prepared in Examples 1-3 and the comparative examples is compared.
[0029] Figure 7 This study compares the performance of the membrane electrodes of Example 1 and Comparative Examples 1-2 when applied to low-temperature hydrogen-oxygen proton exchange membrane fuel cells. Detailed Implementation
[0030] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.
[0031] As mentioned earlier, the existing thermal transfer method for preparing proton exchange membrane fuel cell membrane electrode assemblies has problems such as the catalyst not being completely transferred to the proton exchange membrane, thus affecting the yield of membrane electrode assemblies, and the transfer substrate being deformed by hot pressing and unable to be reused. There is an urgent need to develop a new thermal transfer method for preparing membrane electrodes to improve the transfer rate of the catalyst layer and improve the yield of membrane electrodes.
[0032] To achieve the above objectives, the applicant of this invention, after extensive research, provides a one-step, two-stage hot-pressing transfer method for preparing membrane electrodes, such as... Figure 1 As shown, it includes the following steps:
[0033] S1, the cathode catalyst slurry is coated onto the first transfer substrate to form a cathode catalyst layer, and the anode catalyst slurry is coated onto the second transfer substrate to form an anode catalyst layer.
[0034] The first and second transfer substrates are selected from one or both of PTFE film (polytetrafluoroethylene film) and glass fiber paper, with a thickness of 80μm-150μm.
[0035] The cathode catalyst slurry and anode catalyst slurry are conventional compositions in the art and may include a cathode catalyst (or anode catalyst), a binder, and a solvent. The cathode catalyst may be one or two of platinum black, platinum-carbon supported carbon, and platinum-cobalt supported carbon catalysts, with a platinum content ranging from 20 wt% to 100 wt% and a carbon content ranging from 0 wt% to 80 wt%. The anode catalyst may be a platinum-carbon supported carbon catalyst, with a platinum content ranging from 10 wt% to 40 wt% and a carbon content ranging from 60 wt% to 90 wt%. The binder may be an ionomer, such as Nafion D2020, Nafion D520, Nafion D521, etc. The solvent may be one or more of isopropanol, ethanol, n-propanol, and water. It should be noted that the preparation method of the cathode catalyst slurry or anode catalyst slurry can refer to conventional preparation methods in the art and will not be elaborated here.
[0036] In some embodiments, after the cathode catalyst slurry and anode catalyst slurry are prepared, they are coated onto the first transfer substrate and the second transfer substrate respectively using a slot coating method, and then dried to form the cathode catalyst layer and the anode catalyst layer. The slot coating method helps to ensure uniform coating of the catalyst slurry, and the catalyst utilization rate can be as high as 90% or more. In other embodiments, other coating processes in the art can also be used, which will not be described in detail here.
[0037] In some embodiments, the platinum loading in the formed cathode catalyst layer is set to 0.3 mg / cm³. 2 -1.0mg / cm2 The platinum loading in the anode catalyst layer was set to 0.1 mg / cm³. 2 -0.3mg / cm 2 The specific load capacity setting depends on the actual application requirements.
[0038] S2, the first flat layer, the second transfer substrate with the anode catalyst layer, the proton exchange membrane, the first transfer substrate with the cathode catalyst layer, and the second flat layer are sequentially stacked on a hot press, and the first hot pressing treatment and the second hot pressing treatment are performed sequentially. The cathode catalyst layer and the anode catalyst layer are disposed close to the proton exchange membrane. The processing pressure of the first heat treatment process is less than the processing pressure of the second hot pressing treatment, and the processing time of the first heat treatment process is greater than or equal to the processing time of the second hot pressing treatment.
[0039] As an example, the processing pressure of the first hot pressing treatment is 1 kg / cm². 2 -10kg / cm 2 The processing temperature is 120℃-170℃, and the processing time is 60 seconds-300 seconds; the processing pressure of the second hot pressing treatment is 10 kg / cm². 2 -80kg / cm 2 The processing temperature is 120℃-170℃; the processing time is 10 seconds-60 seconds.
[0040] In some embodiments, the proton exchange membrane comprises a perfluorosulfonic acid type proton exchange membrane, and the thickness of the proton exchange membrane is 40 μm to 160 μm.
[0041] It should be noted that pre-activated proton exchange membranes (such as perfluorosulfonic acid type proton exchange membranes, which require activation before the hot-press transfer process of the catalyst layer) are usually uneven and wrinkled, especially when the proton exchange membrane is thicker. Therefore, existing technologies typically use high-pressure, long-duration heat treatment to pre-smooth the activated proton exchange membrane before transferring the catalyst layer to the cathode and anode catalyst layers under high-pressure, long-duration heat treatment. However, two long-duration high-pressure heat treatments can severely affect the quality and performance of the proton exchange membrane. More importantly, even if the proton exchange membrane is pre-smoothed using high-pressure, long-duration heat treatment, the membrane cannot be 100% flat and some wrinkles still exist. During the subsequent high-pressure heat treatment transfer, the uneven stress between the proton exchange membrane and the catalyst on the transfer substrate further generates wrinkles and bubbles, ultimately resulting in the catalyst layer not being completely transferred to the proton exchange membrane.
[0042] Unlike existing technologies, this invention divides the heat treatment transfer process of the catalyst layer into two stages:
[0043] (1) The first stage is the first hot-pressing treatment: This stage is a long-term low-pressure heat treatment process. In this stage, the long-term heat and low pressure make the proton exchange membrane flat; at the same time, the long-term heat makes the cathode catalyst layer and anode catalyst layer soft and melted, and retains a certain fluidity under low pressure (it can be understood that under high-pressure heat treatment, even if the catalyst layer becomes soft due to heat, the high pressure limits its fluidity and cannot achieve a conformal and tight fit between the catalyst layer and the proton exchange membrane). This allows the cathode catalyst layer and anode catalyst layer to form an initial conformal and tight contact with the proton exchange membrane. This not only makes up for the problem of insufficient material contact tightness that may be caused by the shortened high-pressure heat treatment time, but more importantly, the tight contact between the cathode catalyst layer, anode catalyst layer and proton exchange membrane is a conformal and tight fit contact with no gaps between the interfaces, thereby improving the transfer rate of the cathode catalyst layer and anode catalyst layer to the proton exchange membrane. The transfer rate can reach 100%.
[0044] (2) The next step is the second hot-pressing treatment stage: this stage is a short-duration high-pressure heat treatment process. This stage reduces the high-pressure treatment time on the cathode catalyst layer and the anode catalyst layer, preserves the initial pore structure of the cathode catalyst layer and the anode catalyst layer to the greatest extent, reduces the mass transfer impedance of the membrane electrode, and makes the membrane electrode prepared by the method of the present invention have a higher peak power density.
[0045] The first and second planarization layers help to smooth the proton exchange membrane and the cathode and anode catalyst layers bonded to it during the first and second hot-pressing processes, reducing the generation of bubbles and wrinkles, and improving the uniformity and density of the cathode and anode catalyst layers. In some embodiments, the first and second planarization layers are made of porous materials. The presence of pores further facilitates the removal of bubbles from the interface gaps between the proton exchange membrane and the cathode and anode catalyst layers during the hot-pressing process, increasing the interface contact area and thus improving the transfer rate of the cathode and anode catalyst layers. As an example, the porous materials include carbon paper, carbon cloth, high-temperature paper, etc.; in other embodiments, the first and second planarization layers may also be made of other materials, such as thin steel plates.
[0046] In some embodiments, the areas of the first and second planar layers are greater than or equal to the area of the proton exchange membrane, which helps to balance the forces at various points of the cathode and anode catalyst layers and improve the transfer rate of the catalyst layers.
[0047] In some embodiments, the thickness of the first and second ply layers is 10 μm to 300 μm.
[0048] S3, remove the first and second transfer substrates from the product of step S2, attach carbon paper to both sides, seal the frame, and stamp to form a membrane electrode.
[0049] In another aspect, the present invention provides a membrane electrode assembly prepared by the aforementioned preparation method.
[0050] In another aspect, the present invention provides a fuel cell comprising the aforementioned membrane electrode assembly.
[0051] The technical features of the present invention will be described in detail below with reference to embodiments and accompanying drawings. Unless otherwise specified, the instruments and materials described in the embodiments below can be obtained commercially.
[0052] Example 1
[0053] This embodiment provides a method for preparing a membrane electrode in a one-step, two-stage hot-press transfer process, including:
[0054] S1, prepare the anion catalyst layer and the anode catalyst layer.
[0055] A 60% Pt / C cathode catalyst slurry was coated onto a 100 μm thick glass fiber paper (i.e., the first transfer substrate) using a slot coating method to obtain glass fiber paper coated with a 60% Pt / C cathode catalyst layer. A 20% Pt / C anode catalyst slurry was coated onto a 100 μm thick glass fiber paper (i.e., the second transfer substrate) to obtain glass fiber paper coated with a 20% Pt / C anode catalyst layer. The platinum loading of the anode and cathode catalyst layers was 0.1 mg Pt / cm³, respectively. 2 and 0.5 mg Pt / cm 2 .
[0056] S2, sequentially execute the first hot pressing treatment and the second hot pressing treatment.
[0057] The first layer, the second transfer substrate coated with the anolyte catalyst layer, the proton exchange membrane (60μm), the first transfer substrate coated with the cathode catalyst layer, and the second layer are sequentially stacked and laid flat on a hot press. After setting the hot pressing transfer parameters, the transfer is performed. The first hot pressing stage: temperature 150℃, pressure 5kg / cm². 2 The first hot pressing stage lasts 120 seconds; the second hot pressing stage involves a temperature of 150℃ and a pressure of 30 kg / cm². 2 The transfer takes 30 seconds.
[0058] S3, Finally, the membrane electrode is formed: the first and second transfer substrates of the product in step S2 are removed, carbon paper is attached to both sides, the frame is sealed, and the membrane electrode is obtained by stamping.
[0059] Example 2
[0060] Compared to Example 1, the processing temperatures of the first and second hot-pressing treatments in Example 2 differ from those in Example 1, while other preparation conditions and parameters remain the same as in Example 1. Specifically, in Example 2, the first hot-pressing treatment stage has the following conditions: temperature 130°C and pressure 5 kg / cm². 2 The first hot pressing stage lasts 120 seconds; the second hot pressing stage lasts 130℃ at a pressure of 30 kg / cm². 2 The time is 30 seconds.
[0061] Example 3
[0062] Compared to Example 1, the processing pressure of the second hot-pressing treatment in Example 3 is different from that in Example 1, while other preparation conditions and parameters are the same as in Example 1, including the first hot-pressing treatment conditions in Example 3, which are also the same as in Example 1. Specifically, in Example 3, the first hot-pressing treatment stage has the following conditions: temperature 150°C and pressure 5 kg / cm². 2 The first hot pressing stage lasts 120 seconds; the second hot pressing stage involves a temperature of 150℃ and a pressure of 80 kg / cm². 2 The time is 30 seconds.
[0063] Comparative Example 1
[0064] Compared to Example 1, Comparative Example 1 did not employ a two-stage hot-pressing process. The specific hot-pressing conditions were: temperature 150°C and pressure 30 kg / cm². 2 The time was 150 seconds. Other preparation conditions and parameters were the same as in Example 1.
[0065] Comparative Example 2
[0066] First, cathode and anode catalyst layers were prepared. A 60% Pt / C catalyst slurry was slit-coated onto carbon paper to obtain the cathode catalyst layer, and a 20% Pt / C catalyst slurry was coated onto the carbon paper to obtain the anode catalyst layer. The platinum loading of the anode and cathode catalyst layers was 0.1 mg Pt / cm³, respectively. 2 and 0.5 mg Pt / cm 2 Then, the anode catalyst layer and the cathode catalyst layer are respectively attached to both sides of the proton exchange membrane, and hot pressing and membrane electrode forming are performed to obtain a conventional GDE membrane electrode.
[0067] Figures 2 to 5 The images show actual membrane electrodes after the transfer process in Examples 1-3 and Comparative Example 1, respectively. The results show that the transfer rates of the cathode and anode catalyst layers differ significantly under different hot-pressing conditions of temperature and pressure. In Comparative Example 1, a large portion of the catalyst layer (represented by the black area in the image) was not transferred to the proton exchange membrane. Figure 5 Compared to Comparative Example 1, the catalytic layer transfer rate of the membrane electrodes prepared in Examples 1-3 of this invention is significantly improved. Figures 2-4(Especially Example 1, where the transfer rate reached 100%).
[0068] Figure 6 The figures show the thickness of the membrane electrode after the transfer process in Examples 1-3 and Comparative Example 1. Analysis shows that higher processing pressure and longer processing time result in a loss of thickness in the cathode and anode catalyst layers, leading to reduced porosity and consequently affecting the performance of the membrane electrode. The membrane electrodes obtained in Examples 1 and 2 of this invention exhibit less thickness loss, which is beneficial for ensuring the performance of the membrane electrode.
[0069] In addition, the performance of a 2cm*2cm single cell was tested under hydrogen and oxygen conditions to characterize the performance of the membrane electrode of Example 1 and Comparative Examples 1-2 in an actual fuel cell stack. The polarization curve performance test steps are as follows: (1) Set the test conditions except for the back pressure: cell temperature 60℃, anode / cathode flow rate, etc.; (2) Start loading and activation, while slowly increasing the back pressure to 100kPa; (3) After activation is completed (voltage fluctuates within ±1mV within 60 minutes), reduce the load of the single cell to 0A (reduction range 1A); (4) Adjust the anode / cathode flow rate to maintain the back pressure at about 100kPa, in increments of 10mA, for 1 minute, and use a multimeter to measure 0-0.4A (10-100mA / cm). 2 Record the voltage at the specified current density. In increments of 50 mA, maintain the voltage for 1 minute, and measure the voltage using a multimeter in the range of 0.4-2.0 A (100-500 mA / cm²). 2 Record the voltage at the specified current density. In increments of 100mA, maintain the voltage for 1 minute, and measure the voltage using a multimeter for the range of 2.0-12.0A (500-3000mA / cm). 2 Voltage at current density and record it.
[0070] The results are as follows Figure 7 As shown, the performance of the samples from Example 1 and Comparative Example 2 is basically the same in the activation polarization region. However, starting from the ohmic polarization region, the performance of the transfer CCM film electrode prepared in Example 1 is higher than that of the traditional GDE film electrode, and this difference is even more pronounced in the mass transfer polarization region, where the performance reaches 2000 mA cm⁻¹. -2 Their power densities are 1108 and 1000 mW / cm³, respectively. 2 The difference between the two reached 108 mW / cm 2 Furthermore, the peak power of the comparative example 1 membrane electrode, after prolonged high-voltage treatment, was only 586 mW / cm². 2 This indicates that the membrane electrode prepared by the method in Example 1 of the present invention has better performance.
[0071] In summary, this invention provides a one-step, two-stage hot-press transfer method for preparing membrane electrodes. This method can improve the transfer rate of the catalyst layer while preserving the initial pore structure of the catalyst layer to the greatest extent, thereby increasing the peak power density of the membrane electrode.
[0072] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.
Claims
1. A method for preparing a membrane electrode by one-step two-stage hot-pressing transfer, characterized in that, Includes the following steps: S1, the cathode catalyst slurry is coated onto the first transfer substrate to form a cathode catalyst layer, and the anode catalyst slurry is coated onto the second transfer substrate to form an anode catalyst layer; S2, the first flat layer, the second transfer substrate with the anode catalyst layer, the proton exchange membrane, the first transfer substrate with the cathode catalyst layer and the second flat layer are sequentially stacked and laid flat on a hot press, and the first hot pressing treatment and the second hot pressing treatment are sequentially performed, with the cathode catalyst layer and the anode catalyst layer disposed close to the proton exchange membrane; S3, remove the first and second transfer substrates from the product of step S2, attach carbon paper to both sides, seal the frame, and stamp to form a membrane electrode. Wherein, the processing pressure of the first hot pressing is less than the processing pressure of the second hot pressing, and the processing time of the first hot pressing is greater than or equal to the processing time of the second hot pressing. said first hot pressing treatment has a pressure of 1 kg / cm 2 - 10 kg / cm 2 , a temperature of 120°C - 170°C and a treatment time of 60 seconds - 300 seconds; said second hot pressing treatment has a pressure of 10 kg / cm 2 - 80 kg / cm 2 , a temperature of 120°C - 170°C and a treatment time of 10 seconds - 60 seconds.
2. The method for preparing a film electrode by one-step two-stage hot-pressing transfer as described in claim 1, characterized in that, The first and second paving layers include any one of carbon paper, carbon cloth, high-temperature paper, or thin steel plate.
3. The method for preparing a film electrode by one-step two-stage hot-press transfer as described in claim 1, characterized in that, The area of the first and second planar layers is greater than or equal to the area of the proton exchange membrane.
4. The method for preparing a film electrode by one-step two-stage hot-pressing transfer as described in claim 1, characterized in that, The thickness of the first and second tiling layers is 10 μm to 300 μm.
5. The method for preparing a film electrode by one-step two-stage hot-press transfer as described in claim 1, characterized in that, The thickness of the proton exchange membrane is 40 μm to 160 μm.
6. The method for preparing a film electrode by one-step two-stage hot-pressing transfer as described in claim 1, characterized in that, In step S1, the cathode catalyst slurry and the anode catalyst slurry are coated onto the first transfer substrate and the second transfer substrate respectively using a slot coating method.
7. A membrane electrode assembly, characterized in that, The membrane electrode is prepared by the method according to any one of claims 1-6.