Membrane electrode assembly for electrochemical hydrogen compressor and preparation method of membrane electrode assembly

Abstract

The invention discloses a membrane electrode assembly for an electrochemical hydrogen compressor and a preparation method of the membrane electrode assembly. The membrane electrode assembly comprises a proton exchange membrane, and a slurry layer, a catalyst layer and a slurry layer are sequentially stacked on the surface of the proton exchange membrane; through the sandwich type structural design of the proton exchange membrane, the slurry layer, the catalyst layer and the slurry layer, falling and loss of catalyst particles in the reaction process are reduced, continuous and efficient utilization of a catalyst is guaranteed, more attachment sites are provided for the magnetron sputtering catalyst particles through the rough slurry layer surface, and the reaction efficiency is improved. The catalyst can be uniformly distributed at high density, the problem that catalyst particles are easily agglomerated on a smooth surface is avoided, and finally, excellent performance can still be kept under the condition of relatively low catalyst loading amount.

Description

Technical Field

[0001] This invention belongs to the field of membrane electrode assembly technology, specifically relating to a membrane electrode assembly for an electrochemical hydrogen compressor and its preparation method. Background Technology

[0002] An electrochemical hydrogen compressor is a device based on a redox reaction that converts low-pressure hydrogen into high-pressure hydrogen. Its structure is similar to a proton exchange membrane fuel cell, consisting of a membrane electrode assembly (MEA), a gas diffusion layer, bipolar plates, and end plates. The MEA comprises a proton exchange membrane and a catalyst layer. By applying an external voltage, low-pressure hydrogen is converted into high-pressure hydrogen. A hydrogen oxidation reaction (HOR) occurs at the anode, while a hydrogen evolution reaction (HER) occurs at the cathode. This creates a localized pressure difference between the anode and cathode, thereby compressing the hydrogen.

[0003] In the electrochemical hydrogen compression process, the hydrogen oxidation reaction (HOR) at the anode and the hydrogen evolution reaction (HER) at the cathode occur simultaneously in the catalyst layer. The catalyst layer typically consists of a catalyst and a support. The catalyst lowers the activation energy of the reaction, thereby accelerating the chemical reaction. The catalyst can be deposited on the gas diffusion layer and then pressed onto the proton exchange membrane, or it can be deposited directly on the proton exchange membrane and sandwiched between the gas diffusion layers.

[0004] Platinum catalysts are the most commonly used catalysts in electrochemical hydrogen compression due to their high catalytic activity and fast reaction rate. Platinum also has low resistivity and structural stability. Since platinum is an expensive precious metal, current research focuses on reducing the platinum loading in the catalyst layer to improve the economics of electrochemical hydrogen compression. With the continuous development of catalyst deposition technology, the platinum catalyst loading has been reduced to 0.1 mg / cm³. 2 While excessively high platinum catalyst loading can lead to cost issues, excessively low platinum catalyst loading can also significantly reduce the performance of the anode and cathode. Therefore, an appropriate platinum loading is needed to balance cost and performance.

[0005] Chinese patent CN116575068A discloses a catalyst layer slurry, its preparation method, a membrane electrode, and an electrochemical hydrogen compressor. The catalyst layer slurry comprises the following components by weight: 0.02–0.20 parts platinum-carbon catalyst, 0.005–0.05 parts ionomer, 0.3–0.5 parts alcohol solvent, and 0.3–0.5 parts water solvent; the platinum loading of the platinum-carbon catalyst is 20–70 wt%. The high platinum loading in this catalyst layer increases the cost burden. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a membrane electrode assembly for an electrochemical hydrogen compressor and its preparation method. Through a sandwich structure design of proton exchange membrane → slurry layer → catalyst layer → slurry layer, combined with magnetron sputtering process, it can maintain excellent performance even with a low catalyst loading.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] The present invention provides a membrane electrode assembly for an electrochemical hydrogen compressor, the membrane electrode assembly comprising a proton exchange membrane, wherein a slurry layer, a catalyst layer and a slurry layer are sequentially stacked on the surface of the proton exchange membrane.

[0009] The slurry layer consists of Vulcan XC72 carbon black, isopropanol, and Nafion D2020.

[0010] The weight ratio of Vulcan XC72 carbon black, isopropanol and Nafion D2020 is 1:8~12:1~1.2, preferably 1:10:1.

[0011] The catalyst in the catalyst layer is platinum.

[0012] The catalyst loading is 0.04~0.05 mg / cm³. 2 .

[0013] The proton exchange membrane is a Nafion 117 membrane.

[0014] The present invention also provides a method for preparing the membrane electrode assembly for an electrochemical hydrogen compressor, the method comprising the following steps:

[0015] (1) Pretreatment of proton exchange membrane: The cleaned proton exchange membrane was soaked in hydrogen peroxide solution and sulfuric acid solution in turn, and finally rinsed repeatedly with ultrapure water and then dried;

[0016] (2) Slurry spraying: The slurry is evenly sprayed onto both surfaces of the proton exchange membrane and dried to form a slurry layer;

[0017] (3) Magnetron sputtering: Using platinum as the target material, a catalyst layer is formed on the slurry layer of the proton exchange membrane by magnetron sputtering;

[0018] (4) Slurry spraying: The slurry is evenly sprayed onto the surface of the catalyst layer of the proton exchange membrane and dried to form a slurry layer again.

[0019] In steps (2) and (4), the amount of slurry sprayed on one side is 0.04~0.05 mL / cm. 2 .

[0020] In step (3), the parameters of magnetron sputtering are: sputtering time 200~300 s, current 75~85 mA, argon pressure 0.08~0.12 mbar, and distance between sample holder and platinum target 3~7 cm. Preferably, the parameters are: sputtering time 250 s, current 80 mA, argon pressure 0.09 mbar, and distance between sample holder and platinum target 5 cm.

[0021] Step (4) further includes: placing the prepared membrane electrode assembly in a vacuum furnace for 0.5~1.0 h, setting the pressure to 10~20 mbar and the temperature to 130~140 ℃; preferably: placing the prepared membrane electrode assembly in a vacuum furnace for 1.0 h, setting the pressure to 15 mbar and the temperature to 135 ℃.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The membrane electrode assembly provided by this invention has a three-layer structure on both sides of the proton exchange membrane: two slurry layers and one catalyst layer, with the catalyst layer located between the two slurry layers. The catalyst layer is encapsulated by the two slurry layers, reducing the shedding and loss of catalyst particles during the reaction process, ensuring the continuous and efficient utilization of the catalyst, and ultimately improving the hydrogen compression reaction rate and energy conversion efficiency of the electrochemical hydrogen compressor.

[0024] 2. This invention achieves a rough, porous interface structure on the proton exchange membrane surface by spraying a slurry before magnetron sputtering deposition of the catalyst layer. Compared to a smooth proton exchange membrane surface, the rough surface significantly increases the adhesion area of ​​the catalyst layer, allowing the catalyst particles to fully contact the reactant gas and the proton exchange membrane, thereby increasing the effective proportion of the three-phase reaction interface.

[0025] 3. The catalyst layer of traditional membrane electrode assemblies is mostly prepared by coating, which requires a high catalyst loading to ensure reaction efficiency. However, this solution can significantly reduce the amount of catalyst used while maintaining the same reaction efficiency by increasing the effective contact area, thus greatly reducing the cost of core materials.

[0026] 4. This invention combines magnetron sputtering with slurry spraying, eliminating the need for additional complex equipment or special processing steps. It is compatible with existing membrane electrode assembly production lines, avoiding equipment modification costs. At the same time, the cost of the slurry layer material is negligible compared to the catalyst, further controlling the overall preparation cost.

[0027] 5. The two slurry layers serve as transition layers between the catalyst layer and the proton exchange membrane, and between the catalyst layer and the external diffusion layer, respectively. This can alleviate the interfacial stress differences between different materials and avoid interlayer delamination caused by thermal expansion and contraction or volume changes during the reaction process.

[0028] 6. The outer slurry layer can block impurity particles or electrolyte erosion that may occur during the reaction, reducing catalyst poisoning and loss; at the same time, the porous structure of the slurry layer does not affect the transport of hydrogen and protons, protecting the catalyst without sacrificing reaction efficiency, extending the service life of the membrane electrode assembly, and reducing the maintenance and replacement costs of the equipment. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of the membrane electrode assembly provided by the present invention;

[0030] Figure 2 The linear sweep voltammetry curves are for Examples 1, 2, and 1. Detailed Implementation

[0031] The present invention will now be described in detail with reference to the embodiments.

[0032] Example 1

[0033] A membrane electrode assembly for an electrochemical hydrogen compressor includes a proton exchange membrane, wherein a slurry layer, a catalyst layer, and another slurry layer are sequentially stacked on the surface of the proton exchange membrane.

[0034] The method for preparing the membrane electrode assembly for the electrochemical hydrogen compressor includes the following steps:

[0035] (1) Pretreatment of proton exchange membrane: Place a 5cm×5cm proton exchange membrane in an ultrasonic bath filled with ultrapure water and clean it for 20 minutes. After cleaning, rinse with ultrapure water. Then, place the proton exchange membrane in 3% H2O2 and keep the solution temperature at 80℃ on a hot plate for one hour. Then, clean it with ultrapure water. Then, place the proton exchange membrane in ultrapure water and keep the solution temperature at 80℃ on a hot plate for one hour. Then, place the proton exchange membrane in 0.5mol / L sulfuric acid and keep the solution temperature at 80℃ on a hot plate for one hour. Finally, rinse it repeatedly with ultrapure water to ensure that the residual sulfuric acid is completely removed. The pretreatment of the proton exchange membrane is completed. Store the pretreated proton exchange membrane in ultrapure water for later use.

[0036] (2) Slurry spraying: 0.12g Valcan XC70 carbon black, 1.2g isopropanol and 0.12g Nafion D2020 are ultrasonically mixed evenly to obtain a total slurry volume of 2.4mL. Half of the slurry is evenly sprayed on one side of the proton exchange membrane. Under the premise of ensuring uniform spraying, 5-6 layers can be sprayed. After the spraying is completed and dried, the above spraying operation is repeated on the other side of the proton exchange membrane to form a slurry layer on both surfaces of the proton exchange membrane.

[0037] (3) Magnetron sputtering: Place the completed proton exchange membrane into the chamber of the magnetron sputtering equipment, maintain the vacuum environment of the chamber, dry the proton exchange membrane for one hour, place the proton exchange membrane on the sample holder of the magnetron sputtering equipment, use platinum as the target material, place one side of the completed proton exchange membrane facing the target material, and perform magnetron sputtering using the set parameters: sputtering time of 250s, current of 80mA, argon pressure of 0.09mbar and distance between the sample holder and the platinum target of 5cm. After completing the magnetron sputtering of one side, repeat the above magnetron sputtering operation on the other side of the proton exchange membrane to form a catalyst layer on the slurry layer.

[0038] (4) Slurry spraying: Repeat step (2) to form a slurry layer on top of the catalyst layer;

[0039] (5) In order to improve the adhesion between the sprayed slurry layer and the Nafion 117 film, the prepared membrane electrode assembly was placed in a vacuum furnace for 1 hour, with a pressure of 15 mbar and a temperature of 135 °C.

[0040] In the membrane electrode assembly prepared in this embodiment, the platinum catalyst loading on the anode side is 0.048 mg / cm³. 2 The platinum loading on the cathode side is 0.045 mg / cm³. 2 .

[0041] Example 2

[0042] The rest is the same as in Example 1, except that in the membrane electrode assembly prepared in this example, the platinum catalyst loading on the anode side is 0.042 mg / cm³. 2 The platinum loading on the cathode side is 0.041 mg / cm³. 2 .

[0043] Comparative Example 1

[0044] A membrane electrode assembly for an electrochemical hydrogen compressor includes a proton exchange membrane on the surface of which a catalyst layer is stacked.

[0045] The method for preparing the membrane electrode assembly for the electrochemical hydrogen compressor includes the following steps:

[0046] (1) Pretreatment of proton exchange membrane: Place a 5cm×5cm proton exchange membrane in an ultrasonic bath filled with ultrapure water and clean it for 20 minutes. After cleaning, rinse with ultrapure water. Then, place the proton exchange membrane in 3% H2O2 and keep the solution temperature at 80℃ on a hot plate for one hour. Then, clean it with ultrapure water. Then, place the proton exchange membrane in ultrapure water and keep the solution temperature at 80℃ on a hot plate for one hour. Then, place the proton exchange membrane in 0.5mol / L sulfuric acid and keep the solution temperature at 80℃ on a hot plate for one hour. Finally, rinse it repeatedly with ultrapure water to ensure that the residual sulfuric acid is completely removed. The pretreatment of the proton exchange membrane is completed. Store the pretreated proton exchange membrane in ultrapure water for later use.

[0047] (3) Magnetron sputtering: Place the proton exchange membrane on the sample holder of the magnetron sputtering equipment, use platinum as the target material, and face one side of the completed proton exchange membrane to the target material. Perform magnetron sputtering using the set parameters: sputtering time of 250s, current of 80mA, argon pressure of 0.09mbar and distance between the sample holder and the platinum target of 5cm. After completing the magnetron sputtering of one side, repeat the above magnetron sputtering operation on the other side of the proton exchange membrane to form a catalyst layer on the slurry layer.

[0048] In the membrane electrode assembly prepared in this comparative example, the platinum catalyst loading on the anode side was 0.052 mg / cm³. 2 The platinum loading on the cathode side is 0.052 mg / cm³. 2 .

[0049] Test case

[0050] The membrane electrode assemblies prepared in the above embodiments and comparative examples were hot-pressed with the gas diffusion layer and then installed in an electrochemical cell. The specific process is as follows:

[0051] Step 1: Use carbon paper as a gas diffusion layer. Use two 5cm×5cm gas diffusion layers to sandwich the membrane electrode assembly prepared in each embodiment and comparative example, with the rough side of the gas diffusion layer in contact with the membrane electrode assembly.

[0052] Step 2: Place the gas diffusion layer and the membrane electrode assembly together in the aluminum foil interlayer, and place the aluminum foil in a 1 mm thick polytetrafluoroethylene (PTFE) interlayer.

[0053] Step 3: Use a hot press to perform hot pressing. First, heat the upper plate of the hot press to 130°C and set the pressure to 20 bar, which is equivalent to a force of 21-23 kN.

[0054] Step 4: Place the polytetrafluoroethylene (PTFE) in the upper plate and hot-press for 2 minutes and 30 seconds, then place it in the lower plate and press for 1 minute at room temperature. After hot pressing is complete, install the membrane electrode assembly with the gas diffusion layer into the electrochemical cell.

[0055] After assembly, the battery underwent an airtightness test, followed by rinsing the membrane electrode assembly (MEA) with nitrogen and then hydrogen. The MEA was then heated and humidified using a heater and steam. Linear sweep voltammetry (LSV) measurements were then performed. The potential scan rate was set to 2 mV / s, with a start potential of 0 V and an end potential of 0.5 V. The number of potential steps was set to 10, and data was recorded during the last 50% of each potential step, with the potential range set to -10 V to 10 V.

[0056] Three linear sweep voltammetry experiments were conducted on the batteries assembled using the membrane electrode assemblies from Examples 1, 2, and Comparative Example 1. Figure 2 The figure shows the linear sweep voltammetry curves for two examples and a comparative experiment, with the worst results.

[0057] As shown in the figure, the current density of all three curves increases with increasing potential. Using the membrane electrode assemblies from Examples 1 and 2, the current density of the battery assembled in Example 1 is 15 mA / cm² higher than that of Example 2 at a potential of 0.5V. 2 Compared to the comparative example, both embodiments exhibit higher current densities at a potential of 0.5V, but lower catalyst loadings. This indicates that the membrane electrode assembly prepared by the method of this invention not only significantly reduces the platinum catalyst loading, greatly lowering costs, but also demonstrates good performance.

[0058] The above detailed description of a membrane electrode assembly for an electrochemical hydrogen compressor and its preparation method, with reference to the embodiments, is illustrative rather than limiting. Several embodiments may be listed within the defined scope. Therefore, variations and modifications without departing from the overall concept of the present invention should be within the protection scope of the present invention.

Claims

1. A membrane electrode assembly for an electrochemical hydrogen compressor, characterized in that, The membrane electrode assembly includes a proton exchange membrane, and a slurry layer, a catalyst layer, and another slurry layer are sequentially stacked on the surface of the proton exchange membrane.

2. The membrane electrode assembly for an electrochemical hydrogen compressor according to claim 1, characterized in that, The slurry layer consists of Vulcan XC72 carbon black, isopropanol, and Nafion D2020.

3. The membrane electrode assembly for an electrochemical hydrogen compressor according to claim 2, characterized in that, The weight ratio of Vulcan XC72 carbon black, isopropanol, and Nafion D2020 is 1:8~12:1~1.

2.

4. The membrane electrode assembly for an electrochemical hydrogen compressor according to claim 1, characterized in that, The catalyst in the catalyst layer is platinum.

5. The membrane electrode assembly for an electrochemical hydrogen compressor according to claim 4, characterized in that, The catalyst loading is 0.04~0.05 mg / cm2.

6. The membrane electrode assembly for an electrochemical hydrogen compressor according to claim 1, characterized in that, The proton exchange membrane is a Nafion 117 membrane.

7. The method for preparing a membrane electrode assembly for an electrochemical hydrogen compressor as described in any one of claims 1-6, characterized in that, The preparation method includes the following steps: (1) Pretreatment of proton exchange membrane: The cleaned proton exchange membrane was soaked in hydrogen peroxide solution and sulfuric acid solution in turn, and finally rinsed repeatedly with ultrapure water and then dried; (2) Slurry spraying: The slurry is evenly sprayed onto both surfaces of the proton exchange membrane and dried to form a slurry layer; (3) Magnetron sputtering: Using platinum as the target material, a catalyst layer is formed on the slurry layer of the proton exchange membrane by magnetron sputtering; (4) Slurry spraying: The slurry is evenly sprayed onto the surface of the catalyst layer of the proton exchange membrane and dried to form a slurry layer again.

8. The preparation method according to claim 7, characterized in that, In steps (2) and (4), the amount of slurry sprayed on one side is 0.04~0.05 mL / cm2.

9. The preparation method according to claim 7, characterized in that, In step (3), the parameters for magnetron sputtering are: sputtering time 200~300 s, current 75~85 mA, argon pressure 0.08~0.12 mbar, and distance between sample holder and platinum target 3~7 cm.

10. The preparation method according to claim 7, characterized in that, Step (4) is followed by: placing the prepared membrane electrode assembly into a vacuum furnace for 0.5 to 1.0 h, setting the pressure to 10 to 20 mbar and the temperature to 130 to 140 ℃.

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