A composite proton exchange membrane, its preparation method, and a proton exchange membrane fuel cell.

Abstract

This invention provides a composite proton exchange membrane, its preparation method, and a proton exchange membrane fuel cell. The composite proton exchange membrane includes a reinforcing base fabric and modified perfluorosulfonic acid resin layers disposed on both sides of the reinforcing base fabric. The modified perfluorosulfonic acid resin layers are doped with modifiers, including heteropolyacids and sulfonated polyether ether ketones. This invention simultaneously introduces heteropolyacids and sulfonated polyether ether ketones. Heteropolyacids can adsorb a large number of water molecules, improving the membrane's water retention capacity under high temperature and low humidity conditions; sulfonated polyether ether ketones can rapidly transfer protons, increasing the total number of ion transport groups in the membrane and improving membrane conductivity; furthermore, sulfonated polyether ether ketones have a high glass transition temperature and good stability at high temperatures. Therefore, the synergistic effect of these two components greatly improves the electrical performance of the composite proton exchange membrane, which exhibits extremely high conductivity even under high temperature and low humidity conditions. The fuel cell prepared based on this method exhibits extremely high electrical performance.

Description

Technical Field

[0001] This invention belongs to the field of fuel cell technology, specifically relating to a composite proton exchange membrane, its preparation method, and a proton exchange membrane fuel cell. Background Technology

[0002] Proton exchange membrane fuel cells (PEMFCs) are widely used in aerospace, new energy vehicles, and other fields due to their advantages such as high energy density, low operating temperature, fast start-up speed, and simple structure. Proton exchange membranes (PEMs), as one of the core components, play a crucial role in PEMFCs. Inside the fuel cell, the proton exchange membrane provides a channel for the migration and transport of protons, allowing them to pass through the membrane from the anode to the cathode, forming a loop with the electron transfer in the external circuit to provide current to the outside. Therefore, the performance of the proton exchange membrane plays a very important role in the performance of the fuel cell.

[0003] Currently, the most widely used PEMs are perfluorosulfonic acid proton exchange membranes. However, perfluorosulfonic acid membranes have high requirements for temperature and water content, and the operating temperature range is 70-90℃. Above this temperature, the water content inside the membrane decreases sharply, the conductivity drops rapidly, and the fuel cell performance decreases. Therefore, the membrane performs poorly under high temperature and low humidity conditions.

[0004] Therefore, improving the performance of proton exchange membranes in high-temperature and low-humidity environments, so that fuel cells can exhibit excellent electrical performance, is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a composite proton exchange membrane, its preparation method, and a proton exchange membrane fuel cell. The present invention simultaneously introduces heteropolyacids and sulfonated polyether ether ketones into the composite proton exchange membrane. Heteropolyacids can adsorb a large number of water molecules, enhancing the water retention capacity of the composite proton exchange membrane under high temperature and low humidity conditions; sulfonated polyether ether ketones can rapidly transfer protons, increasing the total number of ion transport groups in the composite membrane and improving its conductivity; furthermore, sulfonated polyether ether ketones have a high glass transition temperature and good stability at high temperatures. Therefore, the synergistic effect of these two components significantly improves the electrical performance of the composite proton exchange membrane, resulting in extremely high conductivity even under high temperature and low humidity conditions. The fuel cell prepared based on this method exhibits extremely high electrical performance.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a composite proton exchange membrane, the composite proton exchange membrane comprising a reinforcing base fabric and modified perfluorosulfonic acid resin layers disposed on both sides of the reinforcing base fabric.

[0008] The modified perfluorosulfonic acid resin layer is doped with a modifier, which includes heteropoly acids and sulfonated polyether ether ketone.

[0009] This invention introduces both heteropolyacids and sulfonated polyether ether ketones (PEEKs) into a composite proton exchange membrane. Heteropolyacids possess high ionic conductivity, and their numerous hydroxyl groups allow for the adsorption of a significant number of water molecules, thus enhancing the water retention capacity of the composite proton exchange membrane under high temperature and low humidity conditions. Sulfonated PEEKs, with their abundant sulfonated groups, can rapidly transfer protons, increasing the total number of ion-transporting groups in the composite membrane and improving its conductivity. Furthermore, sulfonated PEEKs exhibit a high glass transition temperature and good stability at high temperatures, demonstrating excellent proton conductivity and mechanical properties. Therefore, the synergistic effect of these two components significantly improves the electrical performance of the composite proton exchange membrane, maintaining extremely high conductivity even under harsh conditions like high temperature and low humidity. The fuel cell prepared based on this method exhibits exceptionally high electrical performance.

[0010] Preferably, the thickness of the composite proton exchange membrane is 10-50 μm, for example, it can be 10 μm, 20 μm, 30 μm, 40 μm or 50 μm, preferably 10-30 μm, and more preferably 15-20 μm.

[0011] Preferably, the thickness of the modified perfluorosulfonic acid resin layer on one side is 5-9 μm, for example, it can be 5 μm, 6 μm, 7 μm, 8 μm or 9 μm.

[0012] Preferably, based on the mass of the modified perfluorosulfonic acid resin layer, the doping amount of the modifier is 0.5-6 wt%, for example, it can be 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, or 6 wt%.

[0013] In this invention, the appropriate amount of modifier doping can significantly improve the conductivity of the membrane, thereby enhancing the electrical performance of the composite membrane under high temperature and low humidity conditions.

[0014] Preferably, the reinforcing substrate is a polymer microporous film. For example, it could be an expanded polytetrafluoroethylene (ePTFE) microporous film.

[0015] Preferably, the mass ratio of the heteropoly acid to the sulfonated polyether ether ketone is (2-10):(3-20), wherein the heteropoly acid is selected in the range of "2-10", for example, 2, 4, 6, 8 or 10, and the sulfonated polyether ether ketone is selected in the range of "3-20", for example, 3, 5, 10, 15, 20, 25 or 30.

[0016] In this invention, the appropriate mass ratio of heteropolyacid and sulfonated polyether ether ketone can greatly improve the electrical performance of the composite proton exchange membrane. Even in extremely harsh environments such as high temperature and low humidity, the composite proton exchange membrane will have extremely high conductivity.

[0017] Preferably, the heteropolyacid includes phosphotungstic acid and / or phosphosilicate.

[0018] Preferably, the degree of sulfonation of the sulfonated polyether ether ketone is 45-85%, for example, it can be 45%, 50%, 55%, 60%, 65%, 70% / 75%, 80% or 85%, etc., preferably 50-70%, and more preferably 60-70%.

[0019] In this invention, sulfonated polyether ether ketone (PEEK) with a suitable degree of sulfonation can effectively improve proton conductivity, help improve the hydrophilicity of PEEK, and maintain the good mechanical properties and chemical stability of PEEK while improving proton conductivity and hydrophilicity. Furthermore, sulfonated PEEK with a suitable degree of sulfonation can enhance compatibility with other materials.

[0020] In a second aspect, the present invention provides a method for preparing a composite proton exchange membrane as described in the first aspect, the method comprising the following steps:

[0021] A blended film-forming solution is obtained by mixing perfluorosulfonic acid resin film-forming solution, sulfonated polyether ether ketone and heteropoly acid.

[0022] The blended membrane-forming solution is coated on both sides of the reinforcing base fabric, and the composite proton exchange membrane is obtained after drying.

[0023] Preferably, the preparation method of the perfluorosulfonic acid resin film-forming solution includes:

[0024] The perfluorosulfonic acid resin solution is dried to obtain perfluorosulfonic acid resin. Then, the perfluorosulfonic acid resin is mixed with a high-boiling-point solvent and dissolved to obtain the perfluorosulfonic acid resin film-forming solution.

[0025] This invention utilizes the above-described method to prepare a perfluorosulfonic acid resin film-forming solution, which facilitates more efficient dissolution of the perfluorosulfonic acid resin. The drying process removes moisture or other low-boiling-point impurities (such as alcohol solvents, like ethanol) from the resin solution, resulting in a purer and more uniform dissolution of the perfluorosulfonic acid resin in high-boiling-point solvents. Furthermore, the film-forming solution prepared using this method can produce films of better quality, exhibiting improved stability and durability in various applications.

[0026] Preferably, the perfluorosulfonic acid resin solution contains 5-20 wt% perfluorosulfonic acid resin, for example, 5 wt%, 10 wt%, 15 wt%, or 20 wt%. It should be noted that the perfluorosulfonic acid resin solution used in this invention can be purchased externally or prepared in-house.

[0027] Preferably, the high-boiling-point solvent includes any one or a combination of at least two of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, or N-methylpyrrolidone.

[0028] Preferably, the mass fraction of the perfluorosulfonic acid resin film-forming solution is 2-20 wt%, for example, it can be 2 wt%, 5 wt%, 10 wt%, 15 wt%, or 20 wt%.

[0029] It should be noted that the mass fraction of perfluorosulfonic acid resin film-forming solution refers to the percentage of the mass of perfluorosulfonic acid resin in the total mass of the perfluorosulfonic acid resin film-forming solution.

[0030] Preferably, the method for preparing the sulfonated polyether ether ketone includes:

[0031] The polyether ether ketone raw material and the sulfonating agent are mixed and subjected to a sulfonation reaction. After the reaction is completed, sulfonated polyether ether ketone is obtained.

[0032] It should be noted that the polyetheretherketone raw material used in this invention was purchased externally.

[0033] Preferably, the polyetheretherketone raw material is dehydrated before being mixed with the sulfonating agent.

[0034] In this invention, the purpose of dehydration treatment is to prevent the sulfonating agent from being diluted by water when it is mixed with the sulfonating agent for sulfonation reaction, and secondly, to prevent the occurrence of hydrolysis reaction.

[0035] Preferably, the sulfonating agent includes sulfuric acid.

[0036] Preferably, the concentration of the sulfuric acid is 95-98 wt%, for example, it can be 95 wt%, 96 wt%, 97 wt%, or 98 wt%.

[0037] Preferably, the sulfonation reaction temperature is room temperature - 70°C, for example, it can be 30°C, 40°C, 50°C, 60°C, or 70°C. It should be noted that the specific room temperature is not limited in this invention, and it can be within the range of 25±5°C, for example, it can be 20°C, 25°C, or 30°C.

[0038] Preferably, the sulfonation reaction time is 0.5-48h, for example, it can be 0.5h, 1h, 5h, 10h, 15h, 20h, 25h, 30h, 35h, 40h, 45h or 48h.

[0039] Preferably, the method for mixing the perfluorosulfonic acid resin film-forming solution, sulfonated polyether ether ketone, and heteropoly acid includes:

[0040] Sulfonated polyether ether ketone is added to the perfluorosulfonic acid resin film-forming solution to obtain a perfluorosulfonic acid resin film-forming solution doped with sulfonated polyether ether ketone. Then, heteropoly acid is added to obtain a blended film-forming solution.

[0041] Preferably, in the sulfonated polyether ether ketone-doped perfluorosulfonic acid resin film-forming solution, the doping amount of sulfonated polyether ether ketone is 1-6 wt%, for example, it can be 1 wt%, 2 wt%, 3 wt%, 3 wt%, 4 wt%, or 5 wt%.

[0042] Preferably, the heteropoly acid doping amount in the blending film-forming solution is 0.5-5 wt%, for example, it can be 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, or 5 wt%, etc., and preferably 0.6-1.5 wt%.

[0043] Preferably, the reinforcing base fabric is a modified reinforcing base fabric, and the modification method includes corona treatment or plasma surface modification technology.

[0044] In this invention, the purpose of modifying the reinforcing base fabric is to obtain a reinforcing base fabric with better compatibility with the film-forming solution, so that the film-forming solution can penetrate the reinforcing base fabric faster and better, and the two are more firmly bonded after film formation, making them less prone to separation, and the electrical properties are more stable.

[0045] Preferably, during the corona treatment, the corona current is 0.4-0.5A, for example, it can be 0.4A, 0.42A, 0.44A, 0.46A, 0.48A or 0.5A, etc.

[0046] Preferably, the coating method includes an impregnation method.

[0047] Preferably, the drying temperature is 80-90℃, for example, it can be 80℃, 82℃, 84℃, 86℃, 88℃ or 90℃, etc.

[0048] Preferably, the drying time is 24-48 hours, for example, 24 hours, 30 hours, 36 hours, 42 hours, or 48 hours.

[0049] Preferably, the preparation method includes the following steps:

[0050] (1) A perfluorosulfonic acid resin solution with a perfluorosulfonic acid resin content of 5-20 wt% is dried at 50-100℃ (e.g., 50℃, 60℃, 70℃, 80℃, 90℃ or 100℃, etc.) to evaporate the solvent and obtain perfluorosulfonic acid resin; then the perfluorosulfonic acid resin and a high-boiling-point solvent are mixed, stirred and dissolved, and then allowed to stand at 50-60℃ (e.g., 50℃, 52℃, 54℃, 56℃, 58℃ or 60℃, etc.) for 30-40 min (e.g., 30 min, 32 min, 34 min, 36 min, 38 min or 40 min, etc.) and then vacuum degassed to obtain a perfluorosulfonic acid resin film-forming solution with a mass fraction of 2-20 wt%.

[0051] (2) Dehydrate the polyetheretherketone powder for 24-48 hours (e.g., 100℃, 105℃, 110℃, 115℃, or 120℃) at 100-120℃, then add concentrated sulfuric acid and mix. Perform a sulfonation reaction at room temperature to 70℃ for 0.5-48 hours. Afterward, place the reacted solution in an ice-water mixture, stir, let stand, and wash until the solution... The pH value is close to neutral (close to neutral, i.e. close to 7; for example, the pH value of the solution after washing is 6.5-7, such as 6.5, 6.6, 6.7, 6.8, 6.9, or 7, etc.). The precipitated polymer is filtered out and then dried at 60-100°C (e.g., 60°C, 70°C, 80°C, 90°C, or 100°C, etc.) for 24-48 hours (e.g., 24 hours, 30 hours, 36 hours, 42 hours, or 48 hours, etc.) to obtain sulfonated polyether ether ketone.

[0052] (3) Add the sulfonated polyether ether ketone to the perfluorosulfonic acid resin film-forming solution and stir to dissolve, to obtain a perfluorosulfonic acid resin film-forming solution with a sulfonated polyether ether ketone doping amount of 1-6 wt%. Then add heteropoly acid crystals and stir to dissolve. Subsequently, ultrasonically treat for 20-50 min (e.g., 20 min, 30 min, 40 min or 50 min, etc.) to obtain a blended film-forming solution with a heteropoly acid doping amount of 0.5-5 wt%.

[0053] (4) Preheat the blending membrane preparation solution and the mold at 40-60℃ (e.g., 40℃, 45℃, 50℃, 55℃ or 60℃, etc.). After preheating, place the modified reinforcing substrate in the mold, and drip the blending membrane preparation solution into the mold and immerse the modified reinforcing substrate. Then, vacuum dry at 80-90℃ for 24-48h to obtain the composite proton exchange membrane.

[0054] Thirdly, the present invention provides a proton exchange membrane fuel cell, the proton exchange membrane fuel cell comprising a composite proton exchange membrane as described in the first aspect, or a composite proton exchange membrane prepared by the preparation method described in the second aspect.

[0055] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0056] Compared with the prior art, the present invention has the following beneficial effects:

[0057] This invention introduces both heteropolyacids and sulfonated polyether ether ketones (PEEKs) into a composite proton exchange membrane. Heteropolyacids possess high ionic conductivity, and their numerous hydroxyl groups allow for the adsorption of a significant number of water molecules, thus enhancing the water retention capacity of the composite proton exchange membrane under high temperature and low humidity conditions. Sulfonated PEEKs, with their abundant sulfonated groups, can rapidly transfer protons, increasing the total number of ion-transporting groups in the composite membrane and improving its conductivity. Furthermore, sulfonated PEEKs exhibit a high glass transition temperature and good stability at high temperatures, demonstrating excellent proton conductivity and mechanical properties. Therefore, the synergistic effect of these two components significantly improves the electrical performance of the composite proton exchange membrane, maintaining extremely high conductivity even under harsh conditions like high temperature and low humidity. The fuel cell prepared based on this method exhibits exceptionally high electrical performance. Attached Figure Description

[0058] Figure 1 This is a schematic diagram of the structure of the composite proton exchange membrane provided in Example 1 of the present invention.

[0059] Among them, 1-modified reinforced base fabric; 2-modified perfluorosulfonic acid resin layer. Detailed Implementation

[0060] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0061] Example 1

[0062] This embodiment provides a composite proton exchange membrane, the structural schematic of which is shown below. Figure 1 As shown, it includes a modified reinforced base fabric 1 and modified perfluorosulfonic acid resin layers 2 disposed on both sides of the modified reinforced base fabric 1.

[0063] The modified perfluorosulfonic acid resin layer 2 is doped with modifiers, including phosphotungstic acid and sulfonated polyether ether ketone.

[0064] The composite proton exchange membrane has a thickness of 15 μm, and the single-sided thickness of the modified perfluorosulfonic acid resin layer 2 is 5-7 μm; the modified reinforcing base fabric 1 is a modified expanded polytetrafluoroethylene microporous film; based on the mass of the modified perfluorosulfonic acid resin layer 2, the doping amount of the modifier is 1 wt%, the mass ratio of phosphotungstic acid and sulfonated polyether ether ketone is 4:6, and the sulfonation degree of sulfonated polyether ether ketone is 66%.

[0065] This embodiment also provides a method for preparing the above-mentioned composite proton exchange membrane, the method comprising the following steps:

[0066] (1) 100g of perfluorosulfonic acid resin solution with a content of 5wt% was dried at 80℃ to evaporate the solvent and obtain perfluorosulfonic acid resin; an appropriate amount of perfluorosulfonic acid resin was added to a round bottom flask, and 150mL of N,N-dimethylacetamide was added to the round bottom flask. After stirring and dissolving under the action of a magnetic stirrer, the solution was allowed to stand at 55℃ for 35min, and then vacuum degassing was performed to obtain a perfluorosulfonic acid resin film-forming solution with a mass fraction of 5wt%.

[0067] (2) The polyether ether ketone powder was dehydrated at 100°C for 48 hours. A certain amount of the dehydrated polyether ether ketone powder was added to a four-necked flask, and then an excess of 98wt% sulfuric acid was added. The sulfonation reaction was carried out at 25°C for 48 hours. The reaction solution was then placed in an ice-water mixture, stirred for 1 hour, and left to stand overnight. The solution was then washed multiple times with deionized water until the pH value of the solution was close to 7. The precipitated polymer was filtered out and then dried at 80°C for 36 hours to obtain sulfonated polyether ether ketone.

[0068] (3) Sulfonated polyether ether ketone was added to the perfluorosulfonic acid resin film-forming solution and stirred and dissolved under the action of a magnetic stirrer to obtain a perfluorosulfonic acid resin film-forming solution with a sulfonated polyether ether ketone doping amount of 3wt%. Then, phosphotungstic acid crystals were added and stirred and dissolved under the action of a magnetic stirrer. Subsequently, the solution was ultrasonically treated for 35 minutes to obtain a blended film-forming solution with a phosphotungstic acid doping amount of 1wt%.

[0069] (4) A corona treatment device was used to treat the expanded polytetrafluoroethylene microporous film with a corona current of 0.45A to obtain a modified expanded polytetrafluoroethylene microporous film.

[0070] (5) Place the blending membrane preparation solution and the mold on a heating table at 50°C for preheating. After the heating is uniform, lay the modified expanded polytetrafluoroethylene microporous membrane flat and fix it in the mold. Take the blending membrane preparation solution and drop it into the mold so that the blending membrane preparation solution completely immerses the modified expanded polytetrafluoroethylene microporous membrane. Then put it into a vacuum drying oven and vacuum dry it at 85°C for 36 hours to obtain a composite proton exchange membrane.

[0071] Example 2

[0072] This embodiment provides a composite proton exchange membrane, including a modified reinforcing base fabric and modified perfluorosulfonic acid resin layers disposed on both sides of the modified reinforcing base fabric.

[0073] The modified perfluorosulfonic acid resin layer is doped with modifiers, including phosphotungstic acid and sulfonated polyether ether ketone.

[0074] The composite proton exchange membrane has a thickness of 30 μm, and the single-sided thickness of the modified perfluorosulfonic acid resin layer is 10-12 μm. The modified reinforcing base fabric is a modified expanded polytetrafluoroethylene microporous film. Based on the mass of the modified perfluorosulfonic acid resin layer, the doping amount of the modifier is 2 wt%, the mass ratio of phosphosilicate to sulfonated polyether ether ketone is 2:20, and the sulfonation degree of sulfonated polyether ether ketone is 60%.

[0075] This embodiment also provides a method for preparing the above-mentioned composite proton exchange membrane, the method comprising the following steps:

[0076] (1) 100g of perfluorosulfonic acid resin solution with a content of 10wt% was dried at 100℃ to evaporate the solvent and obtain perfluorosulfonic acid resin; an appropriate amount of perfluorosulfonic acid resin was added to a round bottom flask, and 200mL of N,N-dimethylacetamide was added to the round bottom flask. After stirring and dissolving under the action of a magnetic stirrer, the solution was allowed to stand at 50℃ for 40min, and then vacuum degassing was performed to obtain a perfluorosulfonic acid resin film-forming solution with a mass fraction of 10wt%.

[0077] (2) The polyether ether ketone powder was dehydrated at 110°C for 36 hours. A certain amount of the dehydrated polyether ether ketone powder was added to a four-necked flask, and then an excess of 98wt% sulfuric acid was added. The sulfonation reaction was carried out at 40°C for 24 hours. The reaction solution was then placed in an ice-water mixture, stirred for 1 hour, and left to stand overnight. The solution was then washed multiple times with deionized water until the pH value of the solution was close to 7. The precipitated polymer was filtered out and then dried at 60°C for 48 hours to obtain sulfonated polyether ether ketone.

[0078] (3) Sulfonated polyether ether ketone was added to the perfluorosulfonic acid resin film-forming solution and stirred and dissolved under the action of a magnetic stirrer to obtain a perfluorosulfonic acid resin film-forming solution with a sulfonated polyether ether ketone doping amount of 3wt%. Then, phosphosilicate crystals were added and stirred and dissolved under the action of a magnetic stirrer. Subsequently, the solution was ultrasonically treated for 20 minutes to obtain a blended film-forming solution with a phosphosilicate doping amount of 1wt%.

[0079] (4) A corona treatment device was used to treat the expanded polytetrafluoroethylene microporous film with a corona current of 0.4A to obtain a modified expanded polytetrafluoroethylene microporous film.

[0080] (5) Place the blending membrane preparation solution and the mold on a heating table at 40°C for preheating. After the heating is uniform, lay the modified expanded polytetrafluoroethylene microporous membrane flat and fix it in the mold. Take the blending membrane preparation solution and add it dropwise into the mold so that the blending membrane preparation solution completely immerses the modified expanded polytetrafluoroethylene microporous membrane. Then put it into a vacuum drying oven and vacuum dry it at 80°C for 48 hours to obtain a composite proton exchange membrane.

[0081] Example 3

[0082] This embodiment provides a composite proton exchange membrane, including a modified reinforcing base fabric and modified perfluorosulfonic acid resin layers disposed on both sides of the modified reinforcing base fabric.

[0083] The modified perfluorosulfonic acid resin layer is doped with modifiers, including phosphotungstic acid and sulfonated polyether ether ketone.

[0084] The composite proton exchange membrane has a thickness of 50 μm, and the single-sided thickness of the modified perfluorosulfonic acid resin layer is 20-22 μm; the modified reinforcing base fabric is a modified expanded polytetrafluoroethylene microporous film; based on the mass of the modified perfluorosulfonic acid resin layer, the doping amount of the modifier is 4 wt%, the mass ratio of phosphotungstic acid to sulfonated polyether ether ketone is 10:3, and the sulfonation degree of sulfonated polyether ether ketone is 70%.

[0085] This embodiment also provides a method for preparing the above-mentioned composite proton exchange membrane, the method comprising the following steps:

[0086] (1) 100g of perfluorosulfonic acid resin solution with a content of 15wt% was dried at 100℃ to evaporate the solvent and obtain perfluorosulfonic acid resin; an appropriate amount of perfluorosulfonic acid resin was added to a round bottom flask, and 100mL of N,N-dimethylacetamide was added to the round bottom flask. After stirring and dissolving under the action of a magnetic stirrer, the solution was allowed to stand at 60℃ for 30min, and then vacuum degassing was performed to obtain a perfluorosulfonic acid resin film-forming solution with a mass fraction of 20wt%.

[0087] (2) The polyether ether ketone powder was dehydrated at 120°C for 24 hours. A certain amount of the dehydrated polyether ether ketone powder was added to a four-necked flask, and then an excess of 98wt% sulfuric acid was added. The sulfonation reaction was carried out at 50°C for 12 hours. The solution after the reaction was placed in an ice-water mixture, stirred for 1 hour, and left to stand overnight. Then, it was washed multiple times with deionized water until the pH of the solution was close to 7. The precipitated polymer was filtered out and then dried at 100°C for 24 hours to obtain sulfonated polyether ether ketone.

[0088] (3) Sulfonated polyether ether ketone was added to the perfluorosulfonic acid resin film-forming solution and stirred and dissolved under the action of a magnetic stirrer to obtain a perfluorosulfonic acid resin film-forming solution with a sulfonated polyether ether ketone doping amount of 5wt%. Then, phosphotungstic acid crystals were added and stirred and dissolved under the action of a magnetic stirrer. Subsequently, the solution was ultrasonically treated for 50 min to obtain a blended film-forming solution with a phosphotungstic acid doping amount of 2wt%.

[0089] (4) A corona treatment device was used to treat the expanded polytetrafluoroethylene microporous film with a corona current of 0.5A to obtain a modified expanded polytetrafluoroethylene microporous film.

[0090] (5) Place the blending membrane preparation solution and the mold on a heating table at 60°C for preheating. After the heating is uniform, lay the modified expanded polytetrafluoroethylene microporous membrane flat and fix it in the mold. Take the blending membrane preparation solution and add it dropwise into the mold so that the blending membrane preparation solution completely immerses the modified expanded polytetrafluoroethylene microporous membrane. Then put it into a vacuum drying oven and vacuum dry it at 90°C for 24 hours to obtain a composite proton exchange membrane.

[0091] Example 4

[0092] The difference between this embodiment and Embodiment 1 is that, based on the mass of the modified perfluorosulfonic acid resin layer, the amount of modifier doped is 0.4 wt%.

[0093] The remaining preparation methods and parameters are consistent with those in Example 1.

[0094] Example 5

[0095] The difference between this embodiment and Embodiment 1 is that, based on the mass of the modified perfluorosulfonic acid resin layer, the amount of modifier doped is 7wt%.

[0096] The remaining preparation methods and parameters are consistent with those in Example 1.

[0097] Example 6

[0098] The difference between this embodiment and Example 1 is that the mass ratio of phosphotungstic acid and sulfonated polyether ether ketone is 1:20.

[0099] The remaining preparation methods and parameters are consistent with those in Example 1.

[0100] Example 7

[0101] The difference between this embodiment and Example 1 is that the mass ratio of phosphotungstic acid and sulfonated polyether ether ketone is 10:2.

[0102] The remaining preparation methods and parameters are consistent with those in Example 1.

[0103] Example 8

[0104] The difference between this embodiment and embodiment 1 is that step (4) is not performed, that is, the expanded polytetrafluoroethylene microporous film in step (5) is an unmodified expanded polytetrafluoroethylene microporous film.

[0105] The remaining preparation methods and parameters are consistent with those in Example 1.

[0106] Comparative Example 1

[0107] The difference between this comparative example and Example 1 is that no modifier is added to the perfluorosulfonic acid resin layer, i.e., steps (2) and (3) are not performed.

[0108] The remaining preparation methods and parameters are consistent with those in Example 1.

[0109] Comparative Example 2

[0110] The difference between this comparative example and Example 1 is that the modifier does not contain phosphotungstic acid, that is, phosphotungstic acid crystals are not added in step (3).

[0111] The remaining preparation methods and parameters are consistent with those in Example 1.

[0112] Comparative Example 3

[0113] The difference between this comparative example and Example 1 is that the modifier does not contain sulfonated polyether ether ketone, that is, step (2) is not performed, and sulfonated polyether ether ketone is not added in step (3).

[0114] The remaining preparation methods and parameters are consistent with those in Example 1.

[0115] Performance testing

[0116] The composite proton exchange membranes provided in the above embodiments and comparative examples were tested for membrane conductivity, water retention capacity, and glass transition temperature.

[0117] The membrane conductivity was tested using AC impedance spectroscopy at 80°C and 80% RH. The glass transition temperature was tested using differential scanning calorimetry. The water content was tested by subtracting the dry membrane mass from the wet membrane mass after soaking the membrane in water at room temperature (25°C) for 2 hours. The percentage change in water content was obtained by dividing the difference by the dry membrane mass and multiplying by 100%.

[0118] The test results are shown in Table 1.

[0119] Table 1

[0120]

[0121] analyze:

[0122] This invention introduces both heteropolyacids and sulfonated polyether ether ketones into a composite proton exchange membrane. The heteropolyacids enhance the water retention capacity of the composite proton exchange membrane, while the sulfonated polyether ether ketones not only increase the number of ion transport groups and improve membrane conductivity, but also increase the glass transition temperature of the composite proton exchange membrane. The synergistic effect of these two components greatly improves the electrical performance and service life of the composite proton exchange membrane. Even in harsh environments with high temperature and low humidity, this composite proton exchange membrane will exhibit extremely high conductivity.

[0123] As can be seen from the comparison between Example 1 and Examples 4-5, if the amount of modifier doped is too small, it will not be conducive to improving the overall electrical performance of the membrane; if the amount of modifier doped is too large, it will reduce the mechanical strength of the membrane, causing the membrane to easily break due to excessive water absorption, and the glass transition temperature will decrease.

[0124] A comparison of Examples 1 and 6-7 shows that if the mass ratio of phosphotungstic acid to sulfonated polyether ether ketone is too small, it is not conducive to achieving the optimal performance of the membrane; if the mass ratio of phosphotungstic acid to sulfonated polyether ether ketone is too large, it will reduce the thermal stability of the membrane and shorten its service life. Due to thermal expansion and contraction of the membrane, there may be a risk of phosphotungstic acid seeping out of the membrane after a period of use, which will cause the water content of the membrane to drop rapidly, thereby reducing the electrical performance of the membrane under high temperature and low humidity conditions.

[0125] As can be seen from the comparison between Example 1 and Example 8, if an unmodified expanded polytetrafluoroethylene microporous membrane is used, its compatibility with the membrane-forming solution is poor, and the modified perfluorosulfonic acid resin layer and the expanded polytetrafluoroethylene microporous membrane cannot be firmly bonded, resulting in a deterioration in the performance of the composite proton exchange membrane in all aspects.

[0126] As can be seen from the comparison between Example 1 and Comparative Example 1, if the perfluorosulfonic acid resin layer is not doped with a modifier, its conductivity is low, which is not conducive to use under high temperature and low humidity conditions, and will result in poor electrical performance of the battery.

[0127] As can be seen from the comparison between Example 1 and Comparative Example 2, if the modifier does not contain phosphotungstic acid, the water content and conductivity of the membrane will be low, and the overall performance of the membrane will also be poor.

[0128] As can be seen from the comparison between Example 1 and Comparative Example 3, if the modifier does not contain sulfonated polyether ether ketone, the heat resistance stability and electrical properties of the membrane are both poor, and the overall performance of the membrane is also very poor.

[0129] The applicant declares that the present invention is illustrated by the above embodiments, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A composite proton exchange membrane, characterized in that, The composite proton exchange membrane includes a reinforcing base fabric and modified perfluorosulfonic acid resin layers disposed on both sides of the reinforcing base fabric. The modified perfluorosulfonic acid resin layer is doped with a modifier, which includes heteropoly acids and sulfonated polyether ether ketone. Based on the mass of the modified perfluorosulfonic acid resin layer, the doping amount of the modifier is 0.5-6 wt%. The mass ratio of the heteropolyacid to the sulfonated polyether ether ketone is (2-10):(3-20); The reinforcing base fabric is a polymer microporous film; The degree of sulfonation of the sulfonated polyether ether ketone is 45-85%; The reinforcing base fabric is a modified reinforcing base fabric, and the modification method includes corona treatment or plasma surface modification technology.

2. The composite proton exchange membrane according to claim 1, characterized in that, The thickness of the composite proton exchange membrane is 10-50 μm.

3. The composite proton exchange membrane according to claim 1, characterized in that, The thickness of the composite proton exchange membrane is 10-30 μm.

4. The composite proton exchange membrane according to claim 1, characterized in that, The thickness of the composite proton exchange membrane is 15-20 μm.

5. The composite proton exchange membrane according to claim 1, characterized in that, The thickness of the modified perfluorosulfonic acid resin layer on one side is 5-22 μm.

6. The composite proton exchange membrane according to claim 1, characterized in that, The heteropolyacids include phosphotungstic acid and / or phosphosilicate.

7. The composite proton exchange membrane according to claim 1, characterized in that, The degree of sulfonation of the sulfonated polyether ether ketone is 50-70%.

8. The composite proton exchange membrane according to claim 1, characterized in that, The degree of sulfonation of the sulfonated polyether ether ketone is 60-70%.

9. A method for preparing a composite proton exchange membrane as described in any one of claims 1-8, characterized in that, The preparation method includes the following steps: A blended film-forming solution is obtained by mixing perfluorosulfonic acid resin film-forming solution, sulfonated polyether ether ketone and heteropoly acid; The blended membrane preparation solution is applied to both sides of the reinforcing base fabric and dried to obtain the composite proton exchange membrane.

10. The method for preparing the composite proton exchange membrane according to claim 9, characterized in that, The preparation method of the perfluorosulfonic acid resin film-forming solution includes: The perfluorosulfonic acid resin solution is dried to obtain perfluorosulfonic acid resin. Then, the perfluorosulfonic acid resin is mixed with a high-boiling-point solvent and dissolved to obtain the perfluorosulfonic acid resin film-forming solution.

11. The method for preparing the composite proton exchange membrane according to claim 10, characterized in that, The perfluorosulfonic acid resin solution contains 5-20 wt% perfluorosulfonic acid resin.

12. The method for preparing the composite proton exchange membrane according to claim 10, characterized in that, The high-boiling-point solvent includes any one or a combination of at least two of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, or N-methylpyrrolidone.

13. The method for preparing the composite proton exchange membrane according to claim 10, characterized in that, The mass fraction of the perfluorosulfonic acid resin film-forming solution is 2-20 wt%.

14. The method for preparing the composite proton exchange membrane according to claim 9, characterized in that, The method for preparing the sulfonated polyether ether ketone includes: The polyether ether ketone raw material and the sulfonating agent are mixed and subjected to a sulfonation reaction. After the reaction is completed, sulfonated polyether ether ketone is obtained.

15. The method for preparing the composite proton exchange membrane according to claim 14, characterized in that, Before mixing the polyetheretherketone (PEEK) raw material and the sulfonating agent, the PEEK raw material is first dehydrated.

16. The method for preparing the composite proton exchange membrane according to claim 14, characterized in that, The sulfonating agent includes sulfuric acid.

17. The method for preparing the composite proton exchange membrane according to claim 16, characterized in that, The concentration of the sulfuric acid is 95-98 wt%.

18. The method for preparing the composite proton exchange membrane according to claim 14, characterized in that, The sulfonation reaction was carried out at a temperature of room temperature - 70°C.

19. The method for preparing the composite proton exchange membrane according to claim 14, characterized in that, The sulfonation reaction takes 0.5-48 hours.

20. The method for preparing the composite proton exchange membrane according to claim 9, characterized in that, The method for mixing the perfluorosulfonic acid resin film-forming solution, sulfonated polyether ether ketone, and heteropoly acid includes: Sulfonated polyether ether ketone is added to the perfluorosulfonic acid resin film-forming solution to obtain a perfluorosulfonic acid resin film-forming solution doped with sulfonated polyether ether ketone. Then, heteropoly acid is added to obtain a blended film-forming solution.

21. The method for preparing the composite proton exchange membrane according to claim 20, characterized in that, In the perfluorosulfonic acid resin film-forming solution doped with sulfonated polyether ether ketone, the doping amount of sulfonated polyether ether ketone is 1-6 wt%.

22. The method for preparing the composite proton exchange membrane according to claim 20, characterized in that, In the blended film-forming solution, the doping amount of heteropoly acid is 0.5-5 wt%.

23. The method for preparing the composite proton exchange membrane according to claim 20, characterized in that, In the blended film-forming solution, the doping amount of heteropoly acid is 0.6-1.5 wt%.

24. The method for preparing the composite proton exchange membrane according to claim 9, characterized in that, The reinforcing base fabric is a modified reinforcing base fabric, and the modification method includes corona treatment or plasma surface modification technology.

25. The method for preparing the composite proton exchange membrane according to claim 24, characterized in that, During the corona treatment, the corona current is 0.4-0.5A.

26. The method for preparing the composite proton exchange membrane according to claim 9, characterized in that, The coating method includes impregnation.

27. The method for preparing the composite proton exchange membrane according to claim 9, characterized in that, The drying temperature is 80-90℃.

28. The method for preparing the composite proton exchange membrane according to claim 9, characterized in that, The drying time is 24-48 hours.

29. The method for preparing the composite proton exchange membrane according to claim 9, characterized in that, The preparation method includes the following steps: (1) A perfluorosulfonic acid resin solution with a perfluorosulfonic acid resin content of 5-20wt% is dried at 50-100℃ to evaporate the solvent and obtain perfluorosulfonic acid resin; then the perfluorosulfonic acid resin is mixed with a high boiling point solvent, stirred and dissolved, and then allowed to stand at 50-60℃ for 30-40min, followed by vacuum degassing to obtain a perfluorosulfonic acid resin film-forming solution with a mass fraction of 2-20wt%. (2) Dehydrate the polyether ether ketone powder for 24-48 h at 100-120℃, then add concentrated sulfuric acid and mix. Sulfonate the mixture for 0.5-48 h at room temperature-70℃. Then place the solution after reaction in an ice-water mixture, stir, let stand, and wash until the pH of the solution is close to neutral. Filter out the precipitated polymer and dry it for 24-48 h at 60-100℃ to obtain sulfonated polyether ether ketone. (3) Add the sulfonated polyether ether ketone to the perfluorosulfonic acid resin film-forming solution and stir to dissolve to obtain a perfluorosulfonic acid resin film-forming solution with a sulfonated polyether ether ketone doping amount of 1-6 wt%. Then add heteropoly acid crystals and stir to dissolve. Then sonicate for 20-50 min to obtain a blended film-forming solution with a heteropoly acid doping amount of 0.5-5 wt%. (4) Preheat the blending membrane preparation solution and the mold at 40-60℃ respectively. After preheating, place the modified reinforcing base fabric in the mold, and drip the blending membrane preparation solution into the mold and immerse the modified reinforcing base fabric. Then, vacuum dry at 80-90℃ for 24-48h to obtain the composite proton exchange membrane.

30. A proton exchange membrane fuel cell, characterized in that, The proton exchange membrane fuel cell includes a composite proton exchange membrane as described in any one of claims 1-8, or a composite proton exchange membrane prepared by the method described in any one of claims 9-29.

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