A membrane electrode, its preparation method and use

Abstract

The application provides a membrane electrode and a preparation method and application thereof, and the preparation method comprises the following steps: (1) performing water-induced treatment on a substrate, and then performing replication with a template; (2) performing hot pressing after compounding a proton exchange membrane provided with a back film on one side and the template obtained through replication, and the proton exchange membrane is close to the template on one side; (3) coating a cathode catalytic layer slurry on the template side and coating an anode catalytic layer slurry on the proton exchange membrane side after cooling the material obtained in the step (2), and drying to obtain the membrane electrode. The template with nanometer-micron wrinkle is prepared through the water-induced method, and is replicated on the surface of the proton exchange membrane, so that the contact area of the proton exchange membrane and the catalytic layer is increased, and the utilization rate of the material is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of fuel cells, and relates to a membrane electrode and a preparation method and application thereof. BACKGROUND

[0002] A proton exchange membrane fuel cell is a new green energy technology, which generates electricity by using fuel gas and oxygen to undergo electrochemical reactions under the action of a catalyst, and this process occurs in a membrane electrode, which is the most core and key component of the fuel cell.

[0003] At present, the mainstream membrane electrode design is still a seven-layer structure, and the design focus is mainly concentrated on the structure inside the catalyst layer. The structure inside the catalyst layer is mostly designed to be ordered, which improves the material transmission efficiency, but the preparation is relatively complex and the engineering implementation is difficult.

[0004] CN114744263A discloses a fuel cell membrane electrode, which comprises a catalyst layer, a proton exchange membrane and a gas diffusion layer. The proton exchange membrane is an aromatic polymer proton exchange membrane, and the material of the catalyst layer comprises an aromatic ionomer having a structure shown in Formula I, wherein A is the residue of a fluorine-containing bisphenol monomer after removing two phenolic hydroxyl hydrogens, R1 and R2 are independently selected from groups containing sulfonic acid groups and / or carboxylic acid groups, and n is an integer greater than or equal to 20.

[0005] CN110880604A discloses a proton exchange membrane fuel cell membrane electrode and a preparation method thereof. The cathode catalyst layer of the proton exchange membrane fuel cell membrane electrode comprises a cathode inner catalyst layer, a cathode intermediate catalyst layer and a cathode outer catalyst layer which are sequentially stacked. Since the carbon content in the cathode catalyst layer gradually increases from the cathode inner catalyst layer, the cathode intermediate catalyst layer to the cathode outer catalyst layer, and the carbon particles have certain voids and are uniformly distributed.

[0006] The above-mentioned scheme cannot significantly improve the utilization rate of the material by optimizing the catalyst layer inside. SUMMARY

[0007] The purpose of the present application is to provide a membrane electrode and a preparation method and application thereof. The present application is made by a water-induced method to make a template with nanometer and micrometer wrinkles, and the template is copied on the surface of the proton exchange membrane, thereby increasing the contact area of the proton exchange membrane and the catalyst layer and improving the utilization rate of the material.

[0008] To achieve the purpose of the present application, the following technical solutions are adopted:

[0009] In a first aspect, the present application provides a preparation method of a membrane electrode, which comprises the following steps:

[0010] (1) copying a template on a substrate after water-induced treatment of the substrate;

[0011] (2) heat-pressing the proton exchange membrane provided with a back film on one side and the replicated template after compounding them, with the side of the proton exchange membrane close to the template;

[0012] (3) coating the cathode catalytic layer slurry on the template side and the anode catalytic layer slurry on the proton exchange membrane side of the material obtained in step (2) after cooling, and drying to obtain the membrane electrode.

[0013] The present application designs the interface structure of the proton exchange membrane and the catalytic layer. In the preparation process of the membrane electrode of the present application, the substrate is subjected to water-induced treatment in advance. Due to the different solubilities of the substrate and the water-induced material to water, stress deformation occurs between the water-induced material and the substrate layer after water absorption, and micro-nano wrinkles are generated. The structure is replicated on the surface of the proton membrane, so that the micro-morphology of the surface of the proton membrane changes, the interface area of the proton membrane and the catalytic layer is increased, the utilization rate of the catalyst at the interface is improved, and the platinum loading is reduced.

[0014] Preferably, the substrate in step (1) comprises polystyrene.

[0015] Preferably, the thickness of the substrate is 10-200 μm, for example, 10 μm, 50 μm, 100 μm, 150 μm or 200 μm, etc.

[0016] Preferably, the water-induced treatment comprises casting a layer of polyvinylpyrrolidone ethanol aqueous solution on the surface of the substrate, drying and then placing in a boiling water vapor container for drying.

[0017] Preferably, the average molecular weight of the polyvinylpyrrolidone is 20,000-30,000, for example, 20,000, 22,000, 25,000, 28,000 or 30,000, etc.

[0018] Preferably, the mass concentration of the polyvinylpyrrolidone ethanol aqueous solution is 10-50 wt%, for example, 10 wt%, 20 wt%, 30 wt%, 40 wt% or 50 wt%, etc., preferably 20-35 wt%.

[0019] Preferably, the volume ratio of ethanol to water in the polyvinylpyrrolidone ethanol aqueous solution is 2-4:1, for example, 2:1, 2.5:1, 3:1, 3.5:1 or 4:1, etc.

[0020] Preferably, the placing time is 100-150 min, for example, 100 min, 110 min, 120 min, 130 min, 140 min or 150 min, etc.

[0021] Preferably, the drying temperature is 50-60℃, for example, 50℃, 52℃, 55℃, 58℃ or 60℃, etc.

[0022] Preferably, the template of step (1) comprises a PDMS template.

[0023] Preferably, the replicating comprises: mixing and stirring the curing agent and the PDMS to obtain a solution, vacuum drying the substrate treated by trimethylchlorosilane and water in a vacuum drying oven, hot-pressing and casting on the surface of the substrate, and drying to completely solidify and then taking out.

[0024] Preferably, the volume ratio of the curing agent to the PDMS is 5-8:1, for example, 5:1, 6:1, 7:1, or 8:1, etc.

[0025] Preferably, the mixing and stirring time is 1-3 min, for example, 1 min, 1.5 min, 2 min, 2.5 min, or 3 min, etc.

[0026] Preferably, the mixing and stirring speed is 1500-2000 rpm, for example, 1500 rpm, 1600 rpm, 1700 rpm, 1800 rpm, 1900 rpm, or 2000 rpm, etc.

[0027] Preferably, the vacuum drying time is 10-20 min, for example, 10 min, 12 min, 15 min, 18 min, or 20 min, etc.

[0028] Preferably, the drying temperature is 50-80℃, for example, 50℃, 55℃, 60℃, 70℃, or 80℃, etc.

[0029] Preferably, the hot-pressing temperature of step (2) is 130-150℃, for example, 130℃, 135℃, 140℃, 145℃, or 150℃, etc.

[0030] Preferably, the hot-pressing time is 30-50 min, for example, 30 min, 35 min, 40 min, 45 min, or 50 min, etc.

[0031] Preferably, the hot-pressing pressure is 5-10 MPa, for example, 5 MPa, 6 MPa, 7 MPa, 8 MPa, 9 MPa, or 10 MPa, etc.

[0032] Preferably, the proton exchange membrane comprises any one or a combination of at least two of Nafion 211, Nafion 212, HP, XL100, NC700, or Gore.

[0033] Preferably, the cathode catalyst layer slurry and the anode catalyst layer slurry of step (3) each comprise a catalyst, deionized water, an ionomer, and a dispersion solvent.

[0034] Preferably, the solid content of the cathode catalytic layer slurry and the anode catalytic layer slurry is 1-4 wt%, for example, 1 wt%, 2 wt%, 3 wt% or 4 wt%, etc.

[0035] Preferably, the I / C ratio of the cathode catalytic layer slurry and the anode catalytic layer slurry is (0.6-1.0):1, for example, 0.6:1, 0.7:1, 0.8:1, 0.9:1 or 1:1, etc.

[0036] Preferably, the catalyst comprises a platinum carbon catalyst and / or a platinum alloy catalyst.

[0037] Preferably, the mass concentration of the ionomer is 5-30 wt%, for example, 5 wt%, 10 wt%, 15 wt%, 20 wt% or 30 wt%, etc.

[0038] Preferably, the dispersion solvent comprises any one or a combination of at least two of ethanol, n-propanol or isopropanol.

[0039] Preferably, the Pt loading of the cathode catalytic layer of step (3) is 0.20-0.24 mg / cm 2 , for example, 0.2 mg / cm 2 , 0.21 mg / cm 2 , 0.22 mg / cm 2 , 0.23 mg / cm 2 or 0.24 mg / cm 2 , etc.

[0040] Preferably, the Pt loading of the anode catalytic layer is 0.04-0.06 mg / cm 2 , for example, 0.04 mg / cm 2 , 0.045 mg / cm 2 , 0.05 mg / cm 2 , 0.055 mg / cm 2 or 0.06 mg / cm 2 , etc.

[0041] Preferably, the preparation method of the cathode catalytic layer slurry and the anode catalytic layer slurry of step (3) comprises, according to the formula, batching, ultrasonic dispersion and cooling to obtain the slurry.

[0042] Preferably, the speed of ultrasonic dispersion is 10000-20000 rpm, for example, 10000 rpm, 12000 rpm, 15000 rpm, 18000 rpm or 20000 rpm, etc.

[0043] Preferably, the time for the ultrasonic dispersion is 20-40 min, for example, 20 min, 25 min, 30 min, 35 min or 40 min, etc.

[0044] Preferably, the temperature for the cooling is -15-5℃, for example, -15℃, -10℃, -5℃, 0℃ or 5℃, etc.

[0045] Preferably, the coating method in step (3) comprises spraying.

[0046] Preferably, the temperature for the coating is 70-80℃, for example, 70℃, 72℃, 75℃, 78℃ or 80℃, etc.

[0047] Preferably, the speed for the coating is 1-2 mL / min, for example, 1 mL / min, 1.2 mL / min, 1.5 mL / min, 1.8 mL / min or 2 mL / min, etc.

[0048] In the second aspect, the application provides a membrane electrode prepared by the method according to the first aspect.

[0049] Preferably, the membrane electrode comprises a catalytic layer and a proton membrane interface in a pleated shape.

[0050] In the third aspect, the application provides a fuel cell comprising the membrane electrode according to the second aspect.

[0051] Compared with the prior art, the application has the following beneficial effects:

[0052] (1) The application designs the interface structure between the proton membrane and the catalytic layer. Since the solubility of polystyrene and polyvinylpyrrolidone in water is different, the polyvinylpyrrolidone is deformed by stress after absorbing water, and micro-nano pleats are generated. The structure is copied on the surface of the proton membrane, so that the micro-morphology of the surface of the proton membrane is changed, the interface area of the proton membrane and the catalytic layer is increased, the utilization rate of the catalyst at the interface is improved, and the platinum loading is reduced.

[0053] (2) The membrane electrode prepared by the method of the application has a voltage of 0.836 V or more at 200 mA / cm 2 , a voltage of 0.712 V or more at 1200 mA / cm 2 , and a voltage of 0.622 V or more at 2000 mA / cm 2 . BRIEF DESCRIPTION OF DRAWINGS

[0054] Figure 1 is a structural schematic diagram of the membrane electrode according to Example 1 of the application, wherein 1 is a cathode catalytic layer, 2 is a proton exchange membrane, and 3 is an anode catalytic layer. DETAILED DESCRIPTION

[0055] The technical solutions of the present application are further illustrated below by means of specific embodiments. Those skilled in the art should understand that the embodiments are only used for understanding the present application and should not be regarded as specific limitations of the present application.

[0056] Embodiment 1

[0057] This embodiment provides a membrane electrode, and a preparation method thereof is as follows:

[0058] (1) A 50-μm polystyrene substrate is used to cast a layer of 10wt% polyvinylpyrrolidone ethanol aqueous solution on the surface, the volume ratio of ethanol to water is 3:1, the drying temperature is 55°C, and after drying, it is placed in a closed boiling water vapor container for 100 min and naturally cooled to room temperature; it is placed in a vacuum drying box together with trimethylchlorosilane for 15 min; PDMS and a curing agent are mixed and cast on the surface of the substrate to prepare a replicated PDMS template;

[0059] (2) A proton exchange membrane with a back film on one side is placed below the template prepared in step (1), the membrane faces upward, and hot pressing is performed, the pressure is set to 8 MPa, the hot pressing temperature is 140°C, and the pressure is maintained for 40 min;

[0060] (3) 0.2 g of platinum carbon catalyst with a platinum content of 50%, 4 g of deionized water, 80 mg of ionomer (ionomer solution concentration is 10%), and 18 g of dispersion solvent are mixed to obtain a catalyst layer slurry, and after ultrasonic dispersion, the ultrasonic wave spraying machine is used to coat the cathode catalyst layer at 70°C, and the anode catalyst layer is coated on the other layer of the proton exchange membrane to obtain a membrane electrode with a wrinkled shape of the interface between the catalyst layer and the proton exchange membrane.

[0061] The structural schematic diagram of the membrane electrode is shown in Figure 1 , wherein 1 is the cathode catalyst layer, 2 is the proton exchange membrane, and 3 is the anode catalyst layer.

[0062] Embodiment 2

[0063] This embodiment provides a membrane electrode, and a preparation method thereof is as follows:

[0064] (1) A 50-μm polystyrene substrate is used to cast a layer of 10wt% polyvinylpyrrolidone ethanol aqueous solution on the surface, the volume ratio of ethanol to water is 3:1, the drying temperature is 55°C, and after drying, it is placed in a closed boiling water vapor container for 100 min and naturally cooled to room temperature; it is placed in a vacuum drying box together with trimethylchlorosilane for 15 min; PDMS and a curing agent are mixed and cast on the surface of the substrate to prepare a replicated PDMS template;

[0065] (2) Put the proton membrane with back film on the template prepared in step (1) and heat press, with the membrane facing up, the pressure is set to 10 MPa, the heat press temperature is 135℃, and the pressure maintaining time is 40 min;

[0066] (3) Mix 0.2 g of platinum carbon catalyst with platinum content of 50%, 4 g of deionized water, 80 mg of ionomer (ionomer solution concentration is 10%) and 18 g of dispersion solvent to obtain a catalyst layer slurry, and after ultrasonic dispersion, coat the cathode catalyst layer at 75℃ using an ultrasonic spray coating machine, and coat the anode catalyst layer on the other layer of the proton membrane to obtain a membrane electrode with a wrinkled shaped interface of the catalyst layer and the proton membrane.

[0067] Example 3

[0068] The difference between this example and Example 1 is only that the mass concentration of the polyvinylpyrrolidone ethanol aqueous solution in step (1) is 35 wt%, and other conditions and parameters are completely the same as those in Example 1.

[0069] Example 4

[0070] The difference between this example and Example 1 is only that the mass concentration of the polyvinylpyrrolidone ethanol aqueous solution in step (1) is 50 wt%, and other conditions and parameters are completely the same as those in Example 1.

[0071] Comparative Example 1

[0072] The difference between this comparative example and Example 1 is only that no water induction treatment is performed, and other conditions and parameters are completely the same as those in Example 1 (a conventional membrane electrode without wrinkles is prepared).

[0073] Performance test:

[0074] Carbon papers are placed on both sides of the membrane electrode in Examples 1-4 and the comparative example, and a single cell is assembled, with an activation area of 25 cm 2 , and the test is performed under the conditions of a cell temperature of 80℃, a gas excess coefficient H2 / Air = 1.5 / 2.5, a humidity of 50%, and no back pressure, and the test results are shown in Table 1:

[0075] Table 1

[0076]

[0077] As can be seen from Table 1, according to Examples 1-4, the voltage of the membrane electrode prepared by the method of the present application can reach above 0.836V at 200 mA / cm 2 , above 0.712V at 1200 mA / cm 2 , and above 0.622V at 2000 mA / cm 2 .

[0078] From the comparison of Examples 1-4, it can be seen that in the preparation of the membrane electrode according to the present application, the mass concentration of the polyvinylpyrrolidone solution in the water induction process affects the performance of the prepared membrane electrode. When the mass concentration of the polyvinylpyrrolidone solution is controlled to be 20-35 wt.%, the performance of the prepared membrane electrode is better. If the mass concentration of the polyvinylpyrrolidone solution is too low, the wrinkle structure is not obvious and the interface effect is not significant. If the mass concentration of the polyvinylpyrrolidone solution is too high, the wrinkle fluctuation is large, and the proton exchange membrane cannot be completely replicated with the wrinkle structure during hot pressing, thus the performance is decreased.

[0079] From the comparison of Example 1 and Comparative Example 1, it can be seen that in the preparation of the membrane electrode according to the present application, the substrate is subjected to water induction treatment in advance. Due to the different solubilities of the substrate and the water induction material to water, stress deformation occurs between the water induction material and the substrate layer after water absorption, and micro-nano wrinkle is generated. The structure is replicated on the surface of the proton membrane, the micro-morphology of the surface of the proton membrane is changed, the interface area of the proton membrane and the catalytic layer is increased, the utilization rate of the catalyst at the interface is improved, and the platinum loading is reduced.

[0080] The applicant declares that the above description is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto. It should be understood by those skilled in the art that any changes or replacements within the technical scope disclosed by the present application can be easily thought out by those skilled in the art, and all fall within the protection scope and disclosure scope of the present application.

Claims

1. A method for preparing a membrane electrode, characterized by, The preparation method comprises the following steps: (1) performing water-induced treatment on the substrate and then copying with a template; (2) after the proton exchange membrane provided with a back film on one side is combined with the template obtained by copying, hot pressing is performed, and the proton exchange membrane is close to the template on one side; (3) after the material obtained in step (2) is cooled, a cathode catalyst layer slurry is coated on the template side, and an anode catalyst layer slurry is coated on the proton exchange membrane side, and then drying is performed to obtain the membrane electrode; The water-induced treatment in step (1) comprises: casting a layer of polyvinylpyrrolidone ethanol aqueous solution on the surface of the substrate, drying, and then placing in a boiling water vapor container for drying; The template in step (1) comprises a PDMS template; the copying comprises: mixing and stirring a curing agent and PDMS to obtain a solution, placing trimethylchlorosilane and the substrate subjected to water-induced treatment in a vacuum drying oven for vacuum drying, hot casting on the surface of the substrate, drying until complete curing, and then taking out.

2. The production method according to claim 1, wherein The substrate in step (1) comprises polystyrene.

3. The production method according to claim 1, wherein The thickness of the substrate is 10-200 μm.

4. The production method according to claim 1, wherein The average molecular weight of the polyvinylpyrrolidone is 20,000-30,000.

5. The production method according to claim 1, wherein The mass concentration of the polyvinylpyrrolidone ethanol aqueous solution is 10-50 wt%.

6. The production method according to claim 5, wherein The mass concentration of the polyvinylpyrrolidone ethanol aqueous solution is 20-35 wt%.

7. The production method according to claim 1, wherein The volume ratio of ethanol to water in the polyvinylpyrrolidone ethanol aqueous solution is 2-4:

1.

8. The production method according to claim 1, wherein The placing time is 100-150 min.

9. The production method according to claim 1, wherein The drying temperature in the water-induced treatment process is 50-60 ℃.

10. The production method according to claim 1, wherein The volume ratio of the curing agent to PDMS is 5-8:

1.

11. The production method according to claim 1, wherein The mixing and stirring time is 1-3 min.

12. The production method according to claim 1, wherein The mixing and stirring speed is 1,500-2,000 rpm.

13. The production method according to claim 1, wherein The vacuum drying time is 10-20 min.

14. The production method according to claim 1, wherein The drying temperature in the copying process is 50-80 ℃.

15. The production method according to claim 1, wherein The hot pressing temperature in step (2) is 130-150 ℃.

16. The production method according to claim 1, wherein The hot pressing time in step (2) is 30-50 min.

17. The production method according to claim 1, wherein The hot pressing pressure in step (2) is 5-10 MPa.

18. The production method according to claim 1, wherein The proton exchange membrane comprises any one or a combination of at least two of Nafion 211, Nafion 212, HP, XL100, NC700 or Gore.

19. The production method according to claim 1, wherein The cathode catalyst layer slurry and the anode catalyst layer slurry in step (3) each comprise a catalyst, deionized water, an ionomer and a dispersion solvent.

20. The production method according to claim 1, wherein The solid content of the cathode catalyst layer slurry and the anode catalyst layer slurry is 1-4 wt%.

21. The production method according to claim 1, wherein The I / C ratio of the cathode catalyst layer slurry and the anode catalyst layer slurry is (0.6-1.0):

1.

22. The preparation method according to claim 19, characterized in that, The catalyst comprises a platinum-carbon catalyst and / or a platinum alloy catalyst.

23. The production method according to claim 19, wherein The mass concentration of the ionomer is 5-30 wt%.

24. The production method according to claim 19, wherein The dispersion solvent comprises any one or a combination of at least two of ethanol, n-propanol or isopropanol.

25. The production method according to claim 1, wherein The Pt loading of the cathode catalytic layer in step (3) is 0.20-0.24 mg / cm 2 .

26. The production method according to claim 1, wherein The Pt loading of the anode catalytic layer is 0.04-0.06 mg / cm 2 .

27. The production method according to claim 1, wherein The preparation method of the cathode catalyst layer slurry and the anode catalyst layer slurry in step (3) comprises: according to the formula, dosing, ultrasonic dispersion, cooling and then obtaining the slurry.

28. The production method according to claim 27, wherein The ultrasonic dispersion speed is 10,000-20,000 rpm.

29. The production method according to claim 27, wherein The ultrasonic dispersion time is 20-40 min.

30. The preparation method according to claim 27, characterized in that, The temperature of the cooling is -15 to 5℃.

31. The production method according to claim 1, wherein The coating method of step (3) includes spraying.

32. The preparation method according to claim 1, characterized in that, The temperature of the coating is 70 to 80℃.

33. The production method according to claim 1, wherein The speed of the coating is 1 to 2 mL / min.

34. A membrane electrode characterized in that, The membrane electrode is prepared by the method of any one of claims 1-33.

35. The membrane electrode of claim 34, wherein, The membrane electrode includes a catalytic layer in a pleated shape and a proton membrane interface.

36. A fuel cell, characterized by The fuel cell comprises the membrane electrode of claim 34 or 35.

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