Composite proton exchange membrane, preparation method thereof and proton exchange membrane fuel cell

Abstract

The invention provides a composite proton exchange membrane, a preparation method thereof and a proton exchange membrane fuel cell. The composite proton exchange membrane comprises reinforced base cloth and modified perfluorinated sulfonic acid resin layers arranged on the surfaces of the two sides of the reinforced base cloth. The modified perfluorinated sulfonic acid resin layer is doped with a modifier, and the modifier comprises heteropoly acid and sulfonated polyether-ether-ketone. The heteropoly acid and the sulfonated polyether ether ketone are introduced at the same time, and the heteropoly acid can adsorb more water molecules, so that the water retention capacity of the membrane at high temperature and low humidity is improved; sulfonated polyetheretherketone can quickly transfer protons, increase the total number of ion transfer groups in the membrane and improve the conductivity of the membrane; the glass transition temperature of the sulfonated polyetheretherketone is high, and the sulfonated polyetheretherketone also has better stability at high temperature; therefore, the electrical properties of the composite proton exchange membrane are greatly improved through the synergistic cooperation of the two components, and the composite proton exchange membrane also has extremely high conductivity even in a high-temperature and low-humidity environment. The fuel cell prepared on the basis of the composite material shows extremely high electrical properties.

Description

Technical Field

[0001] The invention belongs to the technical field of fuel cells, and in particular relates to a composite proton exchange membrane and a preparation method thereof, and a proton exchange membrane fuel cell. Background Art

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

[0003] The most widely used PEMs at present are perfluorosulfonic acid proton exchange membranes, but perfluorosulfonic acid membranes have high requirements for temperature and water content. The operating temperature range is 70-90°C. Above this temperature, the water content in the membrane drops sharply, the conductivity drops rapidly, and the fuel cell performance decreases. Therefore, the membrane performs poorly under high temperature and low humidity.

[0004] Therefore, how to improve 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 needs to be solved urgently. Summary of the invention

[0005] In view of the deficiencies of the prior art, the object of the present invention is to provide a composite proton exchange membrane and a preparation method thereof and a proton exchange membrane fuel cell. The present invention simultaneously introduces heteropoly acid and sulfonated polyetheretherketone into the composite proton exchange membrane. The heteropoly acid can absorb more water molecules and enhance the water retention capacity of the composite proton exchange membrane under high temperature and low humidity; the sulfonated polyetheretherketone can quickly transfer protons, increase the total number of ion transport groups in the composite membrane, and improve the conductivity of the composite membrane; and the sulfonated polyetheretherketone has a high glass transition temperature and good stability at high temperature; therefore, the two work together to greatly improve the electrical properties of the composite proton exchange membrane, and even in a high temperature and low humidity environment, the composite proton exchange membrane will have extremely high conductivity. The fuel cell prepared based on this exhibits extremely high electrical performance.

[0006] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

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

[0008] The modified perfluorosulfonic acid resin layer is doped with a modifier, and the modifier includes a heteropoly acid and a sulfonated polyetheretherketone.

[0009] The present invention simultaneously introduces heteropoly acid and sulfonated polyetheretherketone into the composite proton exchange membrane. Since the heteropoly acid itself has a high ionic conductivity, a large number of hydroxyl structures of the material can adsorb more water molecules, thereby enhancing the water retention capacity of the composite proton exchange membrane under high temperature and low humidity; the sulfonated polyetheretherketone itself has a large number of sulfonated groups, which can quickly transfer protons, increase the total number of ion transport groups in the composite membrane, and improve the conductivity of the composite membrane; the sulfonated polyetheretherketone has a high glass transition temperature, good stability at high temperature, and excellent proton conductivity and mechanical properties; therefore, the two cooperate to greatly improve the electrical properties of the composite proton exchange membrane, and even in such an extremely harsh environment of high temperature and low humidity, the composite proton exchange membrane will have extremely high conductivity. The fuel cell prepared based on this exhibits extremely high electrical performance.

[0010] Preferably, the composite proton exchange membrane has a thickness of 10-50 μm, for example, 10 μm, 20 μm, 30 μm, 40 μm or 50 μm, etc., preferably 10-30 μm, and more preferably 15-20 μm.

[0011] Preferably, the single-side thickness of the modified perfluorosulfonic acid resin layer is 5-9 μm, for example, 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 0.5-6wt%, for example, 0.5wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt% or 6wt%.

[0013] In the present invention, the doping amount of the appropriate modifier can fully improve the conductivity of the membrane, thereby improving the electrical properties of the composite membrane under high temperature and low humidity.

[0014] Preferably, the reinforcing base fabric is a polymer microporous film, for example, an expanded polytetrafluoroethylene microporous film.

[0015] Preferably, the mass ratio of the heteropolyacid to the sulfonated polyetheretherketone is (2-10):(3-20), wherein the selection range of the heteropolyacid "2-10" can be, for example, 2, 4, 6, 8 or 10, and the selection range of the sulfonated polyetheretherketone "3-20" can be, for example, 3, 5, 10, 15, 20, 25 or 30.

[0016] In the present invention, the heteropoly acid and sulfonated polyetheretherketone in a suitable mass ratio can greatly improve the electrical properties of the composite proton exchange membrane. Even in an extremely harsh environment of high temperature and low humidity, the composite proton exchange membrane will have extremely high conductivity.

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

[0018] Preferably, the sulfonation degree of the sulfonated polyetheretherketone 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 the present invention, the sulfonated polyetheretherketone with an appropriate sulfonation degree can effectively improve the proton conductivity, help improve the hydrophilicity of the polyetheretherketone, and can maintain the good mechanical properties and chemical stability of the polyetheretherketone while improving the proton conductivity and hydrophilicity. In addition, the sulfonated polyetheretherketone with an appropriate sulfonation degree can enhance the compatibility with other materials.

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

[0021] The perfluorosulfonic acid resin film-forming liquid, the sulfonated polyetheretherketone and the heteropoly acid are mixed to obtain a blended film-forming liquid.

[0022] The blended membrane-making liquid is coated on both side surfaces of the reinforced base fabric, and the composite proton exchange membrane is obtained after drying.

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

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

[0025] The present invention adopts the above method to prepare the perfluorosulfonic acid resin film-making liquid, which helps to dissolve the perfluorosulfonic acid resin more effectively. The drying process removes water or other low-boiling impurities (such as alcohol solvents, such as ethanol, etc.) in the resin solution, making the dissolution of the perfluorosulfonic acid resin in the high-boiling point solvent purer and more uniform. In addition, the film-making liquid prepared by this method can make the prepared film have better quality and better stability and durability in the application scenario.

[0026] Preferably, the perfluorosulfonic acid resin content of the perfluorosulfonic acid resin solution is 5-20wt%, for example, 5wt%, 10wt%, 15wt% or 20wt%, etc. It should be noted that the perfluorosulfonic acid resin solution used in the present invention can be purchased or homemade.

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

[0028] Preferably, the mass fraction of the perfluorosulfonic acid resin membrane-forming liquid is 2-20wt%, for example, 2wt%, 5wt%, 10wt%, 15wt% or 20wt%.

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

[0030] Preferably, the preparation method of the sulfonated polyetheretherketone comprises:

[0031] The polyetheretherketone raw material and the sulfonating agent are mixed to carry out a sulfonation reaction, and after the reaction is completed, sulfonated polyetheretherketone is obtained.

[0032] It should be noted that the polyetheretherketone raw material used in the present invention is purchased from outside.

[0033] Preferably, before the polyetheretherketone raw material and the sulfonating agent are mixed, the polyetheretherketone raw material is firstly subjected to a dehydration treatment.

[0034] In the present invention, the purpose of the 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 comprises sulfuric acid.

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

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

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

[0039] Preferably, the method of mixing the perfluorosulfonic acid resin film-making solution, sulfonated polyetheretherketone and heteropoly acid comprises:

[0040] Sulfonated polyetheretherketone is added to a perfluorosulfonic acid resin film-forming liquid to obtain a sulfonated polyetheretherketone-doped perfluorosulfonic acid resin film-forming liquid, and then a heteropoly acid is added to obtain a blended film-forming liquid.

[0041] Preferably, in the sulfonated polyetheretherketone-doped perfluorosulfonic acid resin membrane-forming liquid, the doping amount of sulfonated polyetheretherketone is 1-6wt%, for example, 1wt%, 2wt%, 3wt%, 3wt%, 4wt% or 5wt%.

[0042] Preferably, in the blended membrane-forming solution, the doping amount of the heteropolyacid is 0.5-5wt%, for example, it can be 0.5wt%, 1wt%, 2wt%, 3wt%, 4wt% or 5wt%, etc., preferably 0.6-1.5wt%.

[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 the present invention, the purpose of modifying the reinforced base fabric is to obtain a reinforced base fabric with better matching degree with the film-making liquid, so that the film-making liquid can penetrate the reinforced base fabric faster and better, and the two are more firmly combined after film formation and are not easy to separate, and the electrical performance is more stable.

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

[0046] Preferably, the coating method comprises a dipping method.

[0047] Preferably, the drying temperature is 80-90°C, for example, 80°C, 82°C, 84°C, 86°C, 88°C or 90°C.

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

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

[0050] (1) drying a perfluorosulfonic acid resin solution having a perfluorosulfonic acid resin content of 5-20 wt% at 50-100° C. (for example, 50° C., 60° C., 70° C., 80° C., 90° C. or 100° C., etc.) to evaporate the solvent to obtain a perfluorosulfonic acid resin; then mixing the perfluorosulfonic acid resin with a high boiling point solvent, stirring and dissolving the mixture, and standing the mixture at 50-60° C. (for example, 50° C., 52° C., 54° C., 56° C., 58° C. or 60° C., etc.) for 30-40 min (for example, 30 min, 32 min, 34 min, 36 min, 38 min or 40 min, etc.), followed by vacuum degassing to obtain a perfluorosulfonic acid resin film-making solution having a mass fraction of 2-20 wt%.

[0051] (2) dehydrating the polyetheretherketone powder at 100-120° C. (e.g., 100° C., 105° C., 110° C., 115° C., or 120° C.) for 24-48 h (e.g., 24 h, 30 h, 36 h, 42 h, or 48 h, etc.), then adding concentrated sulfuric acid to the mixture, and performing a sulfonation reaction at room temperature -70° C. for 0.5-48 h, then placing the resulting solution in an ice-water mixture, stirring, standing, and washing until the solution The pH value is close to neutral (close to neutral, that is, close to 7, illustratively, 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 (for example, it can be 60°C, 70°C, 80°C, 90°C or 100°C, etc.) for 24-48h (for example, it can be 24h, 30h, 36h, 42h or 48h, etc.) to obtain sulfonated polyetheretherketone.

[0052] (3) Adding the sulfonated polyetheretherketone to the perfluorosulfonic acid resin film-forming liquid, stirring and dissolving the mixture to obtain a perfluorosulfonic acid resin film-forming liquid with a sulfonated polyetheretherketone doping amount of 1-6wt%, then adding heteropolyacid crystals, stirring and dissolving the mixture, and then ultrasonically treating the mixture for 20-50 min (for example, 20 min, 30 min, 40 min or 50 min, etc.) to obtain a blended film-forming liquid with a heteropolyacid doping amount of 0.5-5wt%.

[0053] (4) Preheating the blended membrane-making liquid and the mold at 40-60°C (for example, 40°C, 45°C, 50°C, 55°C or 60°C, etc.), respectively. After the preheating, the modified reinforcing base is arranged in the mold, and the blended membrane-making liquid is dripped into the mold to immerse the modified reinforcing base cloth, and then vacuum dried at 80-90°C for 24-48h to obtain a composite proton exchange membrane.

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

[0055] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

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

[0057] The present invention simultaneously introduces heteropoly acid and sulfonated polyetheretherketone into the composite proton exchange membrane. Since the heteropoly acid itself has a high ionic conductivity, a large number of hydroxyl structures of the material can adsorb more water molecules, thereby enhancing the water retention capacity of the composite proton exchange membrane under high temperature and low humidity; the sulfonated polyetheretherketone itself has a large number of sulfonated groups, which can quickly transfer protons, increase the total number of ion transport groups in the composite membrane, and improve the conductivity of the composite membrane; the sulfonated polyetheretherketone has a high glass transition temperature, good stability at high temperature, and excellent proton conductivity and mechanical properties; therefore, the two cooperate to greatly improve the electrical properties of the composite proton exchange membrane, and even in such an extremely harsh environment of high temperature and low humidity, the composite proton exchange membrane will have extremely high conductivity. The fuel cell prepared based on this exhibits extremely high electrical performance. BRIEF DESCRIPTION OF THE DRAWINGS

[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] Wherein: 1- modified reinforcing base fabric; 2- modified perfluorosulfonic acid resin layer. DETAILED DESCRIPTION

[0060] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only used to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0061] Example 1

[0062] This embodiment provides a composite proton exchange membrane, and its structural schematic diagram is as follows Figure 1 As shown, it includes a modified reinforced base fabric 1 and a modified perfluorosulfonic acid resin layer 2 arranged on both side surfaces of the modified reinforced base fabric 1 .

[0063] The modified perfluorosulfonic acid resin layer 2 is doped with a modifier, and the modifier includes phosphotungstic acid and sulfonated polyetheretherketone.

[0064] The thickness of the composite proton exchange membrane is 15 μm, and the single-side thickness of the modified perfluorosulfonic acid resin layer 2 is 5-7 μm; the modified reinforced 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 accounts for 1wt%, the mass ratio of phosphotungstic acid and sulfonated polyetheretherketone is 4:6, and the sulfonation degree of the sulfonated polyetheretherketone is 66%.

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

[0066] (1) drying 100 g of a perfluorosulfonic acid resin solution having a perfluorosulfonic acid resin content of 5 wt% at 80° C. to evaporate the solvent to obtain a perfluorosulfonic acid resin; adding an appropriate amount of the perfluorosulfonic acid resin to a round-bottom flask, adding 150 mL of N,N-dimethylacetamide to the round-bottom flask, stirring and dissolving under the action of a magnetic stirrer, standing at 55° C. for 35 minutes, and then vacuum degassing to obtain a perfluorosulfonic acid resin membrane solution having a mass fraction of 5 wt%.

[0067] (2) Dehydrating the polyetheretherketone powder at 100°C for 48 hours; adding a certain amount of the dehydrated polyetheretherketone powder into a four-necked flask, and then adding an excess of 98wt% sulfuric acid, and performing a sulfonation reaction at 25°C for 48 hours. Subsequently, placing the reaction solution in an ice-water mixture, stirring for 1 hour, standing overnight, and then washing with deionized water for multiple times until the pH value of the solution is close to 7, filtering out the precipitated polymer, and then drying at 80°C for 36 hours to obtain the sulfonated polyetheretherketone.

[0068] (3) Sulfonated polyetheretherketone is added to the perfluorosulfonic acid resin film-forming liquid, and the mixture is stirred and dissolved under the action of a magnetic stirrer to obtain a perfluorosulfonic acid resin film-forming liquid with a sulfonated polyetheretherketone doping amount of 3 wt%, and then phosphotungstic acid crystals are added, and the mixture is stirred and dissolved under the action of a magnetic stirrer, followed by ultrasonic treatment for 35 minutes to obtain a blended film-forming liquid with a phosphotungstic acid doping amount of 1 wt%.

[0069] (4) The expanded polytetrafluoroethylene microporous film is subjected to corona treatment by using a corona device, and the corona current is 0.45 A to obtain a modified expanded polytetrafluoroethylene microporous film.

[0070] (5) Preheat the blended membrane-making liquid and the mold on a heating table at 50°C respectively. After being evenly heated, lay the modified expanded polytetrafluoroethylene microporous film flat and fix it in the mold; draw the blended membrane-making liquid and drip it into the mold so that the blended membrane-making liquid completely immerses the modified expanded polytetrafluoroethylene microporous film, and 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 reinforced base fabric, and modified perfluorosulfonic acid resin layers disposed on both side surfaces of the modified reinforced base fabric.

[0073] The modified perfluorosulfonic acid resin layer is doped with a modifier, which includes phosphotungstic acid and sulfonated polyetheretherketone.

[0074] The thickness of the composite proton exchange membrane is 30 μm, and the single-side 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 accounts for 2wt%, the mass ratio of phosphosilicate and sulfonated polyetheretherketone is 2:20, and the sulfonation degree of the sulfonated polyetheretherketone is 60%.

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

[0076] (1) drying 100 g of a perfluorosulfonic acid resin solution having a perfluorosulfonic acid resin content of 10 wt% at 100° C. to evaporate the solvent to obtain a perfluorosulfonic acid resin; adding an appropriate amount of the perfluorosulfonic acid resin to a round-bottom flask, adding 200 mL of N,N-dimethylacetamide to the round-bottom flask, stirring and dissolving under the action of a magnetic stirrer, standing at 50° C. for 40 min, and then vacuum degassing to obtain a perfluorosulfonic acid resin membrane solution having a mass fraction of 10 wt%.

[0077] (2) Dehydrating the polyetheretherketone powder at 110°C for 36 hours; adding a certain amount of the dehydrated polyetheretherketone powder into a four-necked flask, and then adding an excess of 98wt% sulfuric acid, and performing a sulfonation reaction at 40°C for 24 hours. Subsequently, placing the reaction solution in an ice-water mixture, stirring for 1 hour, standing overnight, and then washing with deionized water for multiple times until the pH value of the solution is close to 7, filtering out the precipitated polymer, and then drying at 60°C for 48 hours to obtain sulfonated polyetheretherketone.

[0078] (3) Sulfonated polyetheretherketone is added to the perfluorosulfonic acid resin film-forming liquid, and the mixture is stirred and dissolved under the action of a magnetic stirrer to obtain a perfluorosulfonic acid resin film-forming liquid with a sulfonated polyetheretherketone doping amount of 3 wt%, and then phosphosilicate crystals are added, and the mixture is stirred and dissolved under the action of a magnetic stirrer, followed by ultrasonic treatment for 20 minutes to obtain a blended film-forming liquid with a phosphosilicate doping amount of 1 wt%.

[0079] (4) The expanded polytetrafluoroethylene microporous film is subjected to corona treatment by using a corona device, and the corona current is 0.4 A to obtain a modified expanded polytetrafluoroethylene microporous film.

[0080] (5) Preheat the blended membrane-making liquid and the mold on a heating table at 40°C respectively. After being evenly heated, lay the modified expanded polytetrafluoroethylene microporous film flat and fix it in the mold; draw the blended membrane-making liquid and drip it into the mold so that the blended membrane-making liquid completely immerses the modified expanded polytetrafluoroethylene microporous film, and 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 reinforced base fabric, and modified perfluorosulfonic acid resin layers disposed on both side surfaces of the modified reinforced base fabric.

[0083] The modified perfluorosulfonic acid resin layer is doped with a modifier, which includes phosphotungstic acid and sulfonated polyetheretherketone.

[0084] The thickness of the composite proton exchange membrane is 50 μm, and the single-side 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 accounts for 4wt%, the mass ratio of phosphotungstic acid and sulfonated polyetheretherketone is 10:3, and the sulfonation degree of the sulfonated polyetheretherketone is 70%.

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

[0086] (1) 100 g of a perfluorosulfonic acid resin solution having a perfluorosulfonic acid resin content of 15 wt% is dried at 100° C. to evaporate the solvent to obtain a perfluorosulfonic acid resin; an appropriate amount of the perfluorosulfonic acid resin is added to a round-bottom flask, 100 mL of N,N-dimethylacetamide is added to the round-bottom flask, and after stirring and dissolving under the action of a magnetic stirrer, the mixture is allowed to stand at 60° C. for 30 min, and then vacuum degassed to obtain a perfluorosulfonic acid resin membrane solution having a mass fraction of 20 wt%.

[0087] (2) Dehydrating the polyetheretherketone powder at 120°C for 24 hours; adding a certain amount of the dehydrated polyetheretherketone powder into a four-necked flask, and then adding an excess of 98wt% sulfuric acid, and performing a sulfonation reaction at 50°C for 12 hours. Subsequently, placing the reaction solution in an ice-water mixture, stirring for 1 hour, standing overnight, and then washing with deionized water for multiple times until the pH value of the solution is close to 7, filtering out the precipitated polymer, and then drying at 100°C for 24 hours to obtain sulfonated polyetheretherketone.

[0088] (3) Sulfonated polyetheretherketone is added to the perfluorosulfonic acid resin film-forming liquid, and the mixture is stirred and dissolved under the action of a magnetic stirrer to obtain a perfluorosulfonic acid resin film-forming liquid with a sulfonated polyetheretherketone doping amount of 5 wt%, and then phosphotungstic acid crystals are added, and the mixture is stirred and dissolved under the action of a magnetic stirrer, followed by ultrasonic treatment for 50 minutes to obtain a blended film-forming liquid with a phosphotungstic acid doping amount of 2 wt%.

[0089] (4) The expanded polytetrafluoroethylene microporous film is subjected to corona treatment by using a corona device, and the corona current is 0.5 A to obtain a modified expanded polytetrafluoroethylene microporous film.

[0090] (5) Preheat the blended membrane-making liquid and the mold on a heating table at 60°C respectively. After being evenly heated, lay the modified expanded polytetrafluoroethylene microporous film flat and fix it in the mold; draw the blended membrane-making liquid and drip it into the mold so that the blended membrane-making liquid completely immerses the modified expanded polytetrafluoroethylene microporous film, and 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 the doping amount of the modifier is 0.4 wt % based on the mass of the modified perfluorosulfonic acid resin layer.

[0093] The rest of the preparation methods and parameters were the same as those in Example 1.

[0094] Example 5

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

[0096] The rest of the preparation methods and parameters were the same as those in Example 1.

[0097] Example 6

[0098] The difference between this embodiment and embodiment 1 is that the mass ratio of phosphotungstic acid to sulfonated polyetheretherketone is 1:20.

[0099] The rest of the preparation methods and parameters were the same as those in Example 1.

[0100] Example 7

[0101] The difference between this embodiment and embodiment 1 is that the mass ratio of phosphotungstic acid to sulfonated polyetheretherketone is 10:2.

[0102] The rest of the preparation methods and parameters were the same as 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 rest of the preparation methods and parameters were the same as those in Example 1.

[0106] Comparative Example 1

[0107] The difference between this comparative example and Example 1 is that the perfluorosulfonic acid resin layer is not doped with a modifier, that is, steps (2) and (3) are not performed.

[0108] The rest of the preparation methods and parameters were the same as 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, no phosphotungstic acid crystals are added in step (3).

[0111] The rest of the preparation methods and parameters were the same as 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 polyetheretherketone, that is, step (2) is not performed, and sulfonated polyetheretherketone is not added in step (3).

[0114] The rest of the preparation methods and parameters were the same as those in Example 1.

[0115] Performance Testing

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

[0117] Among them, the test method for membrane conductivity is AC impedance spectroscopy, the temperature is 80°C, and the humidity is 80% RH; the test method for glass transition temperature is differential scanning calorimetry; the test method for water content is: the difference between the wet film mass obtained after the membrane is soaked in water at room temperature (25°C) for 2 hours and the dry film mass, the difference is divided by the mass of the dry film and multiplied by 100% to get the percentage change of water content.

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

[0119] Table 1

[0120]

[0121] analyze:

[0122] The present invention simultaneously introduces heteropoly acid and sulfonated polyetheretherketone into the composite proton exchange membrane, wherein the heteropoly acid can enhance the water retention capacity of the composite proton exchange membrane, and the sulfonated polyetheretherketone can not only increase the number of ion transport groups and improve the membrane conductivity, but also improve the glass transition temperature of the composite proton exchange membrane. The two cooperate synergistically to greatly improve the electrical properties and service life of the composite proton exchange membrane. Even in a relatively harsh environment of high temperature and low humidity, the composite proton exchange membrane will have extremely high conductivity.

[0123] By comparing Example 1 with Examples 4-5, it can be seen that if the doping amount of the modifier is too small, it will not be conducive to improving the overall electrical properties of the film; if the doping amount of the modifier is too large, it will reduce the mechanical strength of the film, causing the film to easily break due to excessive water absorption, and the glass transition temperature will be reduced.

[0124] By comparing Example 1 with Examples 6-7, it can be seen that if the mass ratio of phosphotungstic acid and sulfonated polyetheretherketone is too small, it will not be conducive to achieving the optimal performance of the membrane; if the mass ratio of phosphotungstic acid and sulfonated polyetheretherketone is too large, the thermal stability of the membrane will be reduced and the service life will be shortened. The membrane will expand when heated and contract when cooled. After a period of use, the phosphotungstic acid in the membrane may be at risk of leakage, resulting in a rapid decrease in the water content of the membrane, thereby reducing the electrical properties of the membrane under high temperature and low humidity.

[0125] By comparing Example 1 with Example 8, it can be seen that if an unmodified expanded polytetrafluoroethylene microporous membrane is used, its matching degree with the membrane-making liquid is poor, and the modified perfluorosulfonic acid resin layer and the expanded polytetrafluoroethylene microporous membrane cannot be firmly bonded, resulting in deterioration of various performances of the composite proton exchange membrane.

[0126] From the comparison between Example 1 and Comparative Example 1, it can be seen that 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] From the comparison between Example 1 and Comparative Example 2, it can be seen that if the modifier does not contain phosphotungstic acid, the water content in the membrane is low, the conductivity is low, and the overall performance of the membrane is also biased.

[0128] From the comparison between Example 1 and Comparative Example 3, it can be seen that if the modifier does not contain sulfonated polyetheretherketone, the thermal stability and electrical properties of the membrane are deviated, and the overall performance of the membrane is also poor.

[0129] The applicant declares that the present invention illustrates the process method of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned process steps, that is, it does not mean that the present invention must rely on the above-mentioned process steps to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the raw materials selected by 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 comprises a reinforced base fabric and a modified perfluorosulfonic acid resin layer arranged on both sides of the reinforced base fabric; The modified perfluorosulfonic acid resin layer is doped with a modifier, and the modifier includes a heteropoly acid and a sulfonated polyetheretherketone.

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, preferably 10-30 μm, and more preferably 15-20 μm; Preferably, the single-sided thickness of the modified perfluorosulfonic acid resin layer is 5-22 μm; Preferably, based on the mass of the modified perfluorosulfonic acid resin layer, the doping amount of the modifier is 0.5-6wt%; Preferably, the reinforcing base fabric is a polymer microporous film.

3. The composite proton exchange membrane according to claim 1 or 2, characterized in that: The mass ratio of the heteropoly acid to the sulfonated polyetheretherketone is (2-10):(3-20); Preferably, the heteropolyacid comprises phosphotungstic acid and / or phosphosilicate; Preferably, the sulfonation degree of the sulfonated polyetheretherketone is 45-85%, preferably 50-70%, and more preferably 60-70%.

4. A method for preparing a composite proton exchange membrane according to any one of claims 1 to 3, characterized in that: The preparation method comprises the following steps: Mixing a perfluorosulfonic acid resin film-forming liquid, a sulfonated polyetheretherketone and a heteropoly acid to obtain a blended film-forming liquid; The blended membrane-making liquid is coated on both side surfaces of the reinforced base fabric, and the composite proton exchange membrane is obtained after drying.

5. The preparation method according to claim 4, characterized in that: The preparation method of the perfluorosulfonic acid resin film-making solution comprises: Drying the perfluorosulfonic acid resin solution to obtain a perfluorosulfonic acid resin, and then mixing the perfluorosulfonic acid resin with a high boiling point solvent to dissolve the perfluorosulfonic acid resin to obtain a perfluorosulfonic acid resin film-making solution; Preferably, the perfluorosulfonic acid resin content of the perfluorosulfonic acid resin solution is 5-20wt%; 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; Preferably, the mass fraction of the perfluorosulfonic acid resin membrane-making liquid is 2-20wt%.

6. The preparation method according to claim 4 or 5, characterized in that: The preparation method of the sulfonated polyetheretherketone comprises: The polyetheretherketone raw material and the sulfonating agent are mixed to carry out a sulfonation reaction, and after the reaction is completed, a sulfonated polyetheretherketone is obtained; Preferably, before the polyetheretherketone raw material and the sulfonating agent are mixed, the polyetheretherketone raw material is first dehydrated; Preferably, the sulfonating agent comprises sulfuric acid; Preferably, the concentration of the sulfuric acid is 95-98wt%; Preferably, the temperature of the sulfonation reaction is room temperature-70°C; Preferably, the sulfonation reaction time is 0.5-48h.

7. The preparation method according to any one of claims 4 to 6, characterized in that: The method for mixing the perfluorosulfonic acid resin film-making liquid, sulfonated polyetheretherketone and heteropoly acid comprises: Adding sulfonated polyetheretherketone to a perfluorosulfonic acid resin film-forming liquid to obtain a sulfonated polyetheretherketone-doped perfluorosulfonic acid resin film-forming liquid, and then adding a heteropoly acid to obtain a blended film-forming liquid; Preferably, in the sulfonated polyetheretherketone-doped perfluorosulfonic acid resin membrane-making solution, the doping amount of sulfonated polyetheretherketone is 1-6wt%; Preferably, in the blended membrane-making solution, the doping amount of the heteropoly acid is 0.5-5wt%, preferably 0.6-1.5wt%.

8. The preparation method according to any one of claims 4 to 7, 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; Preferably, during the corona treatment, the corona current is 0.4-0.5A; Preferably, the coating method comprises an impregnation method; Preferably, the drying temperature is 80-90°C; Preferably, the drying time is 24-48 hours.

9. The preparation method according to any one of claims 4 to 8, characterized in that: The preparation method comprises the following steps: (1) drying a perfluorosulfonic acid resin solution having a perfluorosulfonic acid resin content of 5-20 wt% at 50-100° C. to evaporate the solvent to obtain a perfluorosulfonic acid resin; then mixing the perfluorosulfonic acid resin with a high boiling point solvent, stirring and dissolving, standing at 50-60° C. for 30-40 min, and then vacuum degassing to obtain a perfluorosulfonic acid resin film-making solution having a mass fraction of 2-20 wt%; (2) dehydrating the polyetheretherketone powder at 100-120° C. for 24-48 hours, then adding concentrated sulfuric acid to mix, and performing a sulfonation reaction at room temperature -70° C. for 0.5-48 hours, then placing the reaction solution in an ice-water mixture, stirring, standing, and washing until the pH value of the solution is close to neutral, filtering out the precipitated polymer, and then drying at 60-100° C. for 24-48 hours to obtain a sulfonated polyetheretherketone; (3) adding the sulfonated polyetheretherketone to the perfluorosulfonic acid resin film-forming liquid, stirring and dissolving the mixture, to obtain a perfluorosulfonic acid resin film-forming liquid in which the sulfonated polyetheretherketone doping amount is 1-6wt%, and then adding heteropolyacid crystals, stirring and dissolving the mixture, and then ultrasonically treating the mixture for 20-50 minutes to obtain a blended film-forming liquid in which the heteropolyacid doping amount is 0.5-5wt%; (4) Preheating the blended membrane-making liquid and the mold at 40-60° C. respectively. After the preheating, placing the modified reinforcing base in the mold, dripping the blended membrane-making liquid into the mold and immersing the modified reinforcing base cloth, and then vacuum drying at 80-90° C. for 24-48 hours to obtain a composite proton exchange membrane.

10. A proton exchange membrane fuel cell, characterized in that: The proton exchange membrane fuel cell comprises the composite proton exchange membrane as claimed in any one of claims 1 to 3, or a composite proton exchange membrane prepared by the preparation method as claimed in any one of claims 4 to 9.

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