Enhanced long-life proton exchange membrane for hydrogen production by electrolysis of water and preparation method thereof

Abstract

This invention discloses an enhanced long-life proton exchange membrane for hydrogen production via water electrolysis and its preparation method. The enhanced long-life proton exchange membrane for hydrogen production via water electrolysis comprises: a reinforcing material composed of ion exchange fibers, wherein the ion exchange fibers are made of a fluoropolymer with sulfonic acid groups on the side chains; a perfluorosulfonic acid resin, which forms a film on the reinforcing material for gas barrier and proton conduction; and a free radical quencher mixed in the perfluorosulfonic acid resin to capture generated free radicals and improve membrane durability. The thickness of the proton exchange membrane is 50-100 μm. The enhanced long-life proton exchange membrane for hydrogen production via water electrolysis prepared by this invention not only has good conductivity, hydrogen permeability, tensile strength, and water content, but also exhibits better dimensional stability and superior durability.

Description

Technical Field

[0001] This invention relates to the field of polymer preparation, specifically to an enhanced long-life proton exchange membrane for hydrogen production by water electrolysis and its preparation method. Background Technology

[0002] Hydrogen energy has garnered significant global attention due to its abundant resources, renewable nature, storability, and clean, environmentally friendly characteristics. Water electrolysis is the cleanest and most environmentally friendly hydrogen production technology. Among these, proton exchange membrane (PEM) water electrolysis is considered the most promising technology for future development due to its high hydrogen purity and efficiency, low energy consumption, stable performance, and ability to operate at high current densities. Currently, the proton exchange membranes commonly used in PEM water electrolysis are primarily perfluorosulfonic acid membranes, such as the Nafion series from Chemours. Considering the gas barrier properties, durability, and safety factors of proton exchange membranes, the proton exchange membranes currently used in the industry are mostly thick membranes (such as Nafion 117 and Nafion 115), typically exceeding 120 μm in thickness. This leads to increased internal resistance in the electrolyzer, higher energy consumption, and higher costs for the water electrolysis hydrogen production system. Therefore, how to reduce the thickness of the proton exchange membrane while maintaining membrane performance has become a pressing issue for the PEM water electrolysis industry.

[0003] To reduce the thickness of proton exchange membranes (PEMs), reinforced PEMs for water electrolysis are typically prepared by incorporating a reinforcing phase with perfluorosulfonic acid resin. The most representative reinforcing phase is expanded polytetrafluoroethylene (ePTFE). While the addition of ePTFE improves the dimensional stability of the water electrolysis membrane, it also introduces several problems, such as: 1) PTFE microporous membranes lack proton transport properties, and using ePTFE as a reinforcing phase reduces the membrane's proton conductivity and ion transport capacity; 2) PTFE microporous membranes are highly hydrophobic, while perfluorosulfonic acid resin is hydrophilic, leading to easy interfacial phase separation in the resulting reinforced PEM. This makes it difficult for the perfluorosulfonic acid resin solution to completely fill the pores of the reinforcing material, thus compromising the membrane's airtightness.

[0004] In addition to reducing membrane thickness and improving membrane strength and dimensional stability, it is also necessary to address the issue of membrane durability. This is because during the operation of PEM water electrolysis, highly oxidizing free radicals such as hydroxyl radicals and peroxyhydroxyl radicals are generated. These free radicals attack unstable groups and non-fluorinated atoms on the PEM membrane, such as sulfonic acid groups and ether bonds in resin molecules, ultimately leading to membrane degradation and deterioration, affecting various membrane properties, and consequently causing a decline in the performance of PEM water electrolysis. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the defects of existing proton exchange membranes, such as large thickness leading to increased internal resistance, increased energy consumption and high cost, or reduced proton conductivity, ion transport capacity, interfacial phase separation and poor durability. The present invention provides an enhanced long-life proton exchange membrane for hydrogen production by water electrolysis and its preparation method, which has high proton conductivity, good mechanical strength and gas barrier properties, and better durability.

[0006] An enhanced long-life proton exchange membrane for hydrogen production by water electrolysis includes:

[0007] The reinforcing material is composed of ion exchange fibers, wherein the ion exchange fibers are made of a fluoropolymer with sulfonic acid groups on the side chains;

[0008] Perfluorosulfonic acid resins are used to form films on reinforcing materials for gas barrier and proton conduction purposes.

[0009] Metal oxide free radical quenchers, mixed in perfluorosulfonic acid resin, are used to capture generated free radicals and improve the durability of the film;

[0010] The thickness of the proton exchange membrane is 50-100 μm.

[0011] The metal oxide free radical quencher is at least one of Ce2O3, CeO2, MnO, Mn2O3, MnO2, ZnO, and La2O3.

[0012] The metal oxide radical quencher has a mass percentage of 0.01wt%-1wt% in the proton exchange membrane.

[0013] The porosity of the reinforcing material is 70%-90%, preferably 75%-90%;

[0014] And / or, the diameter of the ion exchange fiber is 0.001-50 micrometers;

[0015] And / or, the number average molecular weight of the fluoropolymer with sulfonic acid groups on the side chain is 50,000-1,000,000, and the ion exchange capacity of the fluoropolymer with sulfonic acid groups on the side chain is 0.0001-0.1 mmol / g.

[0016] And / or, the perfluorosulfonic acid resin is at least one of long-branched perfluorosulfonic acid resin or short-branched perfluorosulfonic acid resin;

[0017] And / or, the number average molecular weight of the perfluorosulfonic acid resin is 150,000-700,000, preferably 200,000-600,000; the ion exchange capacity of the perfluorosulfonic acid resin is 0.85-1.6 mmol / g, preferably 0.9-1.4 mmol / g.

[0018] The fluoropolymer with sulfonic acid groups on its side chains was prepared using the following method:

[0019] Preparation of fluoropolymer solution: Dissolve the fluoropolymer in solvent A, wherein the mass fraction of the fluoropolymer is 1-20 wt%.

[0020] Preparation of lithium taurate: Lithium taurate is obtained by dissolving taurine and LiOH in water, reacting them, and then drying.

[0021] Preparation of the product: Under an inert atmosphere, a fluoropolymer solution, lithium taurate and metal oxide are mixed and stirred, and heated to 90-150℃. After reacting for 5-30 hours, the product is obtained by cooling.

[0022] After cooling, the process also includes the steps of obtaining the precipitate from the reaction solution and washing and drying the precipitate;

[0023] Preferably, the process for obtaining the precipitate is as follows: the reaction solution is added to solvent B to precipitate the precipitate; the solvent B is at least one selected from ethanol, acetone, diethyl ether, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide.

[0024] And / or, the process of washing the precipitate is as follows: washing the precipitate with water until it is neutral;

[0025] And / or, the drying conditions are: vacuum drying at 50-100°C for 12-48 hours.

[0026] The solvent A is at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide;

[0027] And / or, the metal oxide is at least one of MgO, CaO, and Al2O3;

[0028] And / or, the molar ratio of taurine to LiOH is 1:(0.5-3);

[0029] And / or, the reaction conditions for the lithium taurine are: stirring at 30-60°C for 3-12 hours.

[0030] And / or, the mass ratio of taurine to fluoropolymer is (0.01-0.5):1, preferably (0.05-0.5):1, more preferably (0.1-0.2):1;

[0031] And / or, the molar ratio of lithium taurine to MgO is 1:(0.5-5); preferably 1:(0.5-2).

[0032] A method for preparing an enhanced long-life proton exchange membrane for hydrogen production by water electrolysis includes:

[0033] Preparation of dispersion: Perfluorosulfonic acid resin and free radical quencher are added to a solvent, dissolved and mixed evenly to form a dispersion;

[0034] Preparation of proton exchange membrane: Obtain a reinforcing material composed of ion exchange fibers, form a film on the reinforcing material with a dispersion, and obtain a proton exchange membrane after evaporation of the solvent.

[0035] The film-forming methods include, but are not limited to, solution casting, solution pouring, screen printing, scraping, spraying, or dipping.

[0036] This invention uses fluorinated polymer ion exchange fibers as reinforcing materials to strengthen perfluorosulfonic acid proton exchange membranes. The reinforcing material can be located at any position in the membrane formed with perfluorosulfonic acid resin as the matrix. For example, the reinforcing material can be located on the upper surface of the membrane formed with perfluorosulfonic acid resin as the matrix, or on the lower surface of the membrane formed with perfluorosulfonic acid resin as the matrix, or in the middle of the membrane formed with perfluorosulfonic acid resin as the matrix; preferably, the reinforcing material is located in the middle of the proton exchange membrane formed with perfluorosulfonic acid resin as the matrix.

[0037] The technical solution of this invention has the following advantages:

[0038] 1. In this invention, a fluoropolymer with sulfonic acid groups on its side chains is used as the material for the ion exchange fiber. After the ion exchange fiber is prepared into a reinforcing material, it not only has high mechanical strength and high mechanical strength, effectively ensuring that the membrane performance does not decrease under the condition of reduced proton exchange membrane thickness; but also, because the ion exchange fiber of the fluoropolymer with sulfonic acid groups on its side chains has ion exchange groups, it can reduce the hydrophobicity of the reinforcing fiber and improve the interfacial bonding between the reinforcing material and the perfluorosulfonic acid resin; at the same time, the fluoropolymer ion exchange fiber, while serving as a reinforcing material, also has a certain ion conductivity, and can work synergistically with the perfluorosulfonic acid resin as a proton conduction carrier, effectively improving the ion conductivity of the reinforced proton exchange membrane for water electrolysis.

[0039] Moreover, the present invention adds free radical quenchers to the membrane, and these free radical quenchers have a strong ability to remove free radicals generated during PEM water electrolysis, thereby protecting the membrane from free radical attack during use and improving its durability.

[0040] Therefore, the enhanced long-life proton exchange membrane for hydrogen production by water electrolysis prepared in this invention can still have good mechanical strength and dimensional stability while reducing the thickness, and can even effectively enhance ionic conductivity and improve durability, with very significant effects.

[0041] 2. In the preparation method of the fluoropolymer with sulfonic acid groups on the side chain of the present invention, commercially available fluoropolymers are used as basic raw materials. The fluoropolymer with sulfonic acid groups on the side chain can be obtained in one step by adding inexpensive taurine. This not only greatly reduces the preparation cost, but also provides mild reaction conditions and is easy to implement. At the same time, the content of sulfonic acid groups on the polymer (i.e., the ion exchange capacity of the polymer) in the method of the present invention can be precisely controlled by the ratio of fluoropolymer to taurine during the reaction, thereby obtaining fluoropolymers with sulfonic acid groups on the side chain with different exchange capacities. Therefore, the fluoropolymer with sulfonic acid groups on the side chain of the present invention is well applicable to proton exchange membranes, and the production process has the advantages of being simple, controllable, economical, environmentally friendly, and suitable for mass production. Detailed Implementation

[0042] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0043] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0044] Example 1

[0045] An enhanced long-life proton exchange membrane for hydrogen production via water electrolysis is prepared as follows:

[0046] (1) Select a long-branched perfluorosulfonic acid resin with an ion exchange capacity of 0.91 mmol / g and a number average molecular weight of 400,000 and 0.01 wt% of Ce2O3, and use dimethyl sulfoxide to dissolve it to form a dispersion with a perfluorosulfonic acid content of 20 wt%.

[0047] (2) Fluoropolymer I was prepared into a reinforcing material composed of ion exchange fibers using conventional electrospinning process. The electrospinning process parameters were: voltage 40kV, distance between receiving plate and electrospinning tube 12cm; the diameter of the prepared ion exchange fibers was 0.5-1.2 micrometers; the porosity of the prepared reinforcing material was 90% and the thickness was 10μm.

[0048] (3) Immerse the reinforcing material in the above dispersion. After the reinforcing material is completely wetted, take out the membrane and heat it to evaporate the solvent to obtain a proton exchange membrane with a thickness of 50 μm.

[0049] In step (2), the fluoropolymer I has a number-average molecular weight of 50,000 and an ion exchange capacity of 0.0001 mmol / g. Its preparation process is as follows:

[0050] A PVDF-HFP (polyvinylidene fluoride-hexafluoropropylene) polymer solution was obtained by dissolving dried PVDF-HFP in N,N-dimethylformamide, wherein the mass fraction of PVDF-HFP was 10 wt%. Taurine and LiOH were dissolved in water, wherein the molar ratio of taurine to LiOH was 1:1. After stirring at 50 °C for 12 hours, the solution was dried for 24 hours to obtain lithium taurate. Under nitrogen atmosphere and stirring, lithium taurate and MgO were added to the PVDF-HFP polymer solution, wherein the mass ratio of taurine to PVDF-HFP was 0.5:1 and the molar ratio of lithium taurate to MgO was 1:2. The solution was heated to 90 °C and reacted for 10 hours. After cooling to room temperature, the reactants were poured into acetone to precipitate. The resulting product was then washed with water until neutral. Finally, the product was vacuum dried at 60 °C for 36 hours to obtain a PVDF-HFP polymer with sulfonic acid groups on the side chain, namely fluoropolymer I.

[0051] Example 2

[0052] An enhanced long-life proton exchange membrane for hydrogen production via water electrolysis is prepared as follows:

[0053] (1) Select a long-branched perfluorosulfonic acid resin with an ion exchange capacity of 1.4 mmol / g and a number-average molecular weight of 600,000 and 1 wt% of its weight of CeO2, and use N,N-dimethylformamide to dissolve it to form a dispersion with a perfluorosulfonic acid content of 15 wt%.

[0054] (2) Fluoropolymer I was prepared into a reinforcing material composed of ion exchange fibers using conventional electrospinning process. The electrospinning process parameters were: voltage 30kV, distance between receiving plate and electrospinning tube 15cm, and the diameter of the ion exchange fibers was 0.001-0.8 micrometers. The porosity of the prepared reinforcing material was 70% and the thickness was 10μm.

[0055] (3) Immerse the reinforcing material in the above dispersion. After the reinforcing material is completely wetted, take out the membrane and heat it to evaporate the solvent to obtain a proton exchange membrane with a thickness of 100 μm.

[0056] In step (2), the fluoropolymer I has a number-average molecular weight of 1 million and an ion exchange capacity of 0.1 mmol / g. Its preparation process is as follows:

[0057] A PVDF-HFP (polyvinylidene fluoride-hexafluoropropylene) polymer solution was obtained by dissolving dried PVDF-HFP in N,N-dimethylformamide, wherein the mass fraction of PVDF-HFP was 10 wt%. Taurine and LiOH were dissolved in water, wherein the molar ratio of taurine to LiOH was 1:2. After stirring at 60 °C for 10 hours, the solution was dried for 24 hours to obtain lithium taurate. Under a nitrogen atmosphere and stirring, lithium taurate and MgO were added to the PVDF-HFP polymer solution, wherein the mass ratio of taurine to PVDF-HFP was 0.3:1 and the molar ratio of lithium taurate to MgO was 1:5. The solution was heated to 100 °C and reacted for 24 hours. After cooling to room temperature, the reactants were poured into acetone to precipitate. The resulting product was then washed with water until neutral. Finally, the product was vacuum dried at 60 °C for 48 hours to obtain a PVDF-HFP polymer with sulfonic acid groups on the side chain, namely fluoropolymer I.

[0058] Example 3

[0059] An enhanced long-life proton exchange membrane for hydrogen production via water electrolysis is prepared as follows:

[0060] (1) Select a long-branched perfluorosulfonic acid resin with an ion exchange capacity of 1.6 mmol / g and a number average molecular weight of 700,000 and 0.05 wt% of its weight of MnO, and use N,N-dimethylacetamide to dissolve it to form a dispersion with a perfluorosulfonic acid content of 20 wt%.

[0061] (2) Fluoropolymer I was prepared into a reinforcing material composed of ion exchange fibers using conventional electrospinning process. The electrospinning process parameters were: voltage 40kV, distance between receiving plate and electrospinning tube 15cm, diameter of ion exchange fibers 25-50 micrometers; porosity of the prepared reinforcing material was 70% and thickness was 10μm.

[0062] (3) The reinforcing material is immersed in the above dispersion. After the reinforcing material is completely wetted, the membrane is taken out and heated to evaporate the solvent to obtain a proton exchange membrane with a thickness of 80 μm.

[0063] In step (2), the fluoropolymer I has a number-average molecular weight of 50,000 and an ion exchange capacity of 0.001 mmol / g. Its preparation process is as follows:

[0064] A PVDF-HFP (polyvinylidene fluoride-hexafluoropropylene) polymer solution was obtained by dissolving dried PVDF-HFP in N,N-dimethylformamide, wherein the mass fraction of PVDF-HFP was 15 wt%. Taurine and LiOH were dissolved in water, wherein the molar ratio of taurine to LiOH was 1:0.5. After stirring at 30°C for 3 hours, the solution was dried for 24 hours to obtain lithium taurate. Under a nitrogen atmosphere and stirring, lithium taurate and MgO were added to the PVDF-HFP polymer solution, wherein the mass ratio of taurine to PVDF-HFP was 0.05:1 and the molar ratio of lithium taurate to MgO was 1:0.5. The solution was heated to 90°C and reacted for 5 hours. After cooling to room temperature, the reactants were poured into acetone to precipitate. The resulting product was then washed with water until neutral. Finally, the product was vacuum dried at 50°C for 24 hours to obtain a PVDF-HFP polymer with sulfonic acid groups on the side chain, namely fluoropolymer I.

[0065] Example 4

[0066] An enhanced long-life proton exchange membrane for hydrogen production via water electrolysis is prepared as follows:

[0067] (1) Select a short-branched perfluorosulfonic acid resin with an ion exchange capacity of 0.85 mmol / g and a number average molecular weight of 400,000 and 0.01 wt% of Mn2O3, and use dimethyl sulfoxide to dissolve it to form a dispersion with a perfluorosulfonic acid content of 15 wt%.

[0068] (2) Fluoropolymer I was prepared into a reinforcing material composed of ion exchange fibers using conventional electrospinning process. The electrospinning process parameters were: voltage 50kV, distance between receiving plate and electrospinning tube 10cm, and the diameter of the ion exchange fibers was 10-20 micrometers. The porosity of the prepared reinforcing material was 80% and the thickness was 12μm.

[0069] (3) Immerse the reinforcing material in the above dispersion. After the reinforcing material is completely wetted, take out the membrane and heat it to evaporate the solvent to obtain a proton exchange membrane with a thickness of 50 μm.

[0070] Among them, fluoropolymer I has a number-average molecular weight of 500,000 and an ion exchange capacity of 0.05 mmol / g. Its preparation process is as follows:

[0071] A PVDF-HFP (polyvinylidene fluoride-hexafluoropropylene) polymer solution was obtained by dissolving dried PVDF-HFP in N,N-dimethylformamide, with a PVDF-HFP mass fraction of 15 wt%. Taurine and LiOH were dissolved in water at a molar ratio of 1:3. The mixture was stirred at 60 °C for 10 hours and then dried for 72 hours to obtain lithium taurate. Under a nitrogen atmosphere and stirring, lithium taurate and CaO were added to the PVDF-HFP polymer solution at a mass ratio of 0.5:1 for taurine and 1:2 for lithium taurate and CaO. The mixture was heated to 150 °C and reacted for 30 hours. After cooling to room temperature, the reactants were poured into acetone to precipitate. The resulting product was then washed with water until neutral. Finally, the product was vacuum dried at 100 °C for 36 hours to obtain a PVDF-HFP polymer with sulfonic acid groups on the side chain, i.e., fluoropolymer I.

[0072] Example 5

[0073] An enhanced long-life proton exchange membrane for hydrogen production via water electrolysis is prepared as follows:

[0074] A short-branched perfluorosulfonic acid resin with an ion exchange capacity of 0.91 mmol / g and a number-average molecular weight of 400,000 and 1 wt% of its weight of La2O3 were selected and dissolved with N-methylpyrrolidone to form a dispersion with a perfluorosulfonic acid content of 20 wt%.

[0075] (2) Fluoropolymer II was prepared into a reinforcing material composed of ion exchange fibers using conventional electrospinning process. The electrospinning process parameters were: voltage 40kV, distance between receiving plate and electrospinning tube 12cm, and the diameter of the ion exchange fibers was 0.5-3 micrometers. The porosity of the prepared reinforcing material was 90% and the thickness was 10μm.

[0076] (3) Immerse the reinforcing material in the above dispersion. After the reinforcing material is completely wetted, take out the membrane and heat it to evaporate the solvent to obtain a proton exchange membrane with a thickness of 100 μm.

[0077] Among them, fluoropolymer II has a number-average molecular weight of 800,000 and an ion exchange capacity of 0.1 mmol / g. Its preparation process is as follows:

[0078] Dry PVDF (polyvinylidene fluoride) polymer was dissolved in N,N-dimethylformamide to obtain a PVDF polymer solution with a PVDF mass fraction of 12 wt%. Taurine and LiOH were dissolved in water with a molar ratio of 1:1. The mixture was stirred at 50°C for 6 hours and then dried for 24 hours to obtain lithium taurate. Under a nitrogen atmosphere and stirring, lithium taurate and Al2O3 were added to the PVDF polymer solution with a mass ratio of 0.2:1 for taurine and PVDF polymer and a molar ratio of 1:2 for lithium taurate and Al2O3. The mixture was heated to 100°C and reacted for 20 hours. After cooling to room temperature, the reactants were poured into acetone to precipitate. The resulting product was then washed with water until neutral. Finally, the product was vacuum dried at 80°C for 24 hours to obtain a PVDF polymer with sulfonic acid groups on the side chain, i.e., fluoropolymer II.

[0079] Example 6

[0080] An enhanced long-life proton exchange membrane for hydrogen production via water electrolysis is prepared as follows:

[0081] A long-branched perfluorosulfonic acid resin with an ion exchange capacity of 1.25 mmol / g and a number-average molecular weight of 700,000 and 0.5 wt% of Ce2O3 were selected and dissolved in dimethyl sulfoxide to form a dispersion with a perfluorosulfonic acid content of 10 wt%.

[0082] (2) Fluoropolymer II was prepared into a reinforcing material composed of ion exchange fibers using conventional electrospinning process. The electrospinning process parameters were: voltage 30kV, distance between receiving plate and electrospinning tube 15cm, and the diameter of the ion exchange fibers was 10-15 micrometers. The porosity of the prepared reinforcing material was 85% and the thickness was 10μm.

[0083] (3) Immerse the reinforcing material in the above dispersion. After the reinforcing material is completely wetted, take out the membrane and heat it to evaporate the solvent to obtain a proton exchange membrane with a thickness of 100 μm.

[0084] Among them, fluoropolymer II has a number-average molecular weight of 500,000 and an ion exchange capacity of 0.1 mmol / g. Its preparation process is as follows:

[0085] Dry PVDF (polyvinylidene fluoride) polymer was dissolved in N,N-dimethylformamide to obtain a PVDF polymer solution with a PVDF mass fraction of 15 wt%. Taurine and LiOH were dissolved in water with a molar ratio of 1:2. The mixture was stirred at 60°C for 10 hours and then dried for 24 hours to obtain lithium taurate. Under a nitrogen atmosphere and stirring, lithium taurate and MgO were added to the PVDF polymer solution with a mass ratio of 0.3:1 for taurine and 1:2 for lithium taurate and MgO. The mixture was heated to 110°C and reacted for 24 hours. After cooling to room temperature, the reactants were poured into acetone to precipitate. The resulting product was then washed with water until neutral. Finally, the product was vacuum dried at 60°C for 48 hours to obtain a PVDF polymer with sulfonic acid groups on the side chain, i.e., fluoropolymer II.

[0086] Comparative Example 1

[0087] An enhanced long-life proton exchange membrane for hydrogen production via water electrolysis is prepared as follows:

[0088] A long-branched perfluorosulfonic acid resin with an ion exchange capacity of 0.91 mmol / g and a number-average molecular weight of 400,000 was selected and dissolved in dimethyl sulfoxide to form a 20 wt% perfluorosulfonic acid solution. The PVDF-HFP polymer was then used to prepare a reinforcing material composed of ion exchange fibers using a conventional electrospinning process. The electrospinning process parameters were: a voltage of 40 kV and a distance of 12 cm between the receiving plate and the electrospinning tube. The diameter of the prepared ion exchange fibers was 0.5-1.2 μm. The porosity of the prepared reinforcing material was 90%, and the thickness was 10 μm. The reinforcing material was immersed in the above perfluorosulfonic acid solution. After the reinforcing material was completely wetted, the membrane was removed, and the solvent was evaporated by heating to obtain a proton exchange membrane with a thickness of 50 μm.

[0089] Experimental Example 1:

[0090] The enhanced proton exchange membranes for water electrolysis prepared in Examples 1-6 and the commercial Nafion 117 membrane were subjected to performance tests. The test results are shown in Table 1.

[0091] The swelling rate was tested under the following conditions: temperature 80℃, relative humidity 100%, soaking time 24h, and the initial length and width of the proton exchange membrane were 2cm. 2cm, where X is the length direction, Y is the width direction, and Z is the thickness direction.

[0092] Table 1. Performance comparison of membranes prepared in the examples and commercial membranes.

[0093]

[0094] Comparing the data in Table 1, it can be seen that the enhanced proton exchange membrane for water electrolysis prepared in the examples, with a reduced thickness, exhibits comparable performance in conductivity, hydrogen permeability, tensile strength, and water content to the commercial Nafion 117 perfluorosulfonic acid proton exchange membrane. Furthermore, the swelling ratio of the enhanced proton exchange membrane prepared in the examples is significantly lower than that of the commercial Nafion 117 perfluorosulfonic acid proton exchange membrane, indicating better dimensional stability. These data demonstrate that the proton exchange membrane prepared by this invention achieves better performance while using less perfluorosulfonic acid resin, resulting in a more economical cost.

[0095] Experimental Example 2:

[0096] The durability of the membrane was tested using Fenton's reagent, and the specific procedure is as follows:

[0097] First, prepare Fenton's reagent (add 20 ppm Fe to a 30 wt% H₂O₂ aqueous solution). 2+ Then cut the membrane into 2cm pieces. A 2 cm sample was placed in Fenton's reagent, heated to 80°C, and treated for 120 hours. The Fenton's reagent was replaced every hour during the process, and the membrane was always kept submerged. After the Fenton experiment, the remaining solution was collected, and the fluoride ion content was determined by ion chromatography. The results are shown in Table 2 below.

[0098] The test conditions for ion chromatography included the use of an anion exchange column, a mobile phase consisting of a mixture of Na₂CO₃ and NaHCO₃ at concentrations of 1.8 mmol / L and 1.7 mmol / L, a flow rate of 0.7 ml / min, and a column temperature of 35 °C.

[0099] Table 2 Comparison of fluoride ion release rates between membranes prepared in the examples and commercial membranes

[0100]

[0101] As shown in Table 2, compared with the commercial Nafion 117 membrane, the membrane prepared in this example has a lower fluoride ion release rate and better durability.

[0102] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. An enhanced long-life proton exchange membrane for hydrogen production via water electrolysis, characterized in that, include: The reinforcing material is composed of ion exchange fibers, wherein the ion exchange fibers are made of a fluorinated polymer with sulfonic acid groups on the side chains; Perfluorosulfonic acid resins are used to form films on reinforcing materials for gas barrier and proton conduction purposes; Free radical quenchers, mixed in perfluorosulfonic acid resin, are used to capture generated free radicals and improve the durability of the membrane; The thickness of the proton exchange membrane is 50-100 μm; The fluoropolymer with sulfonic acid groups on its side chains was prepared using the following method: Preparation of fluoropolymer solution: Dissolve the fluoropolymer in solvent A, wherein the mass fraction of the fluoropolymer is 1-20 wt%. Preparation of lithium taurate: Lithium taurate is obtained by dissolving taurine and LiOH in water, reacting them, and then drying. Preparation of the product: Under an inert atmosphere, a fluoropolymer solution, lithium taurate and metal oxide are mixed and stirred, and heated to 90-150℃. After reacting for 5-30 hours, the product is obtained by cooling. The solvent A is at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide; The metal oxide is at least one of MgO, CaO, and Al2O3; The molar ratio of taurine to LiOH is 1:(0.5-3). The reaction conditions for the lithium taurate are: stirring at 30-60℃ for 3-12 hours; The mass ratio of taurine to fluoropolymer is (0.01-0.5):1; The molar ratio of lithium taurine to MgO is 1:(0.5-5). The fluoropolymer includes PVDF or PVDF-HPF.

2. The proton exchange membrane according to claim 1, characterized in that, The free radical quencher is a metal oxide free radical quencher.

3. The proton exchange membrane according to claim 2, characterized in that, The free radical quencher is at least one of Ce2O3, CeO2, MnO, Mn2O3, MnO2, ZnO, and La2O3.

4. The proton exchange membrane according to claim 2, characterized in that, The metal oxide free radical quencher is 0.01wt%-1wt% of the weight of the perfluorosulfonic acid resin.

5. The proton exchange membrane according to claim 1, characterized in that, The porosity of the reinforcing material is 70%-90%.

6. The proton exchange membrane according to claim 1, characterized in that, The porosity of the reinforcing material is 75-90%.

7. The proton exchange membrane according to claim 1, characterized in that, The diameter of the ion exchange fiber is 0.001-50 micrometers.

8. The proton exchange membrane according to claim 1, characterized in that, The fluoropolymer with sulfonic acid groups on its side chain has a number average molecular weight of 50,000-1,000,000 and an ion exchange capacity of 0.0001-0.1 mmol / g.

9. The proton exchange membrane according to claim 1, characterized in that, The perfluorosulfonic acid resin is at least one of long-branched perfluorosulfonic acid resin or short-branched perfluorosulfonic acid resin.

10. The proton exchange membrane according to claim 1, characterized in that, The number-average molecular weight of the perfluorosulfonic acid resin is 150,000 to 700,000; the ion exchange capacity of the perfluorosulfonic acid resin is 0.85 to 1.6 mmol / g.

11. The proton exchange membrane according to claim 10, characterized in that, The perfluorosulfonic acid resin has a number-average molecular weight of 200,000 to 600,000 and an ion exchange capacity of 0.9 to 1.4 mmol / g.

12. The proton exchange membrane according to claim 1, characterized in that, After cooling, the process also includes the steps of obtaining the precipitate from the reaction solution and washing and drying the precipitate.

13. The proton exchange membrane according to claim 12, characterized in that, The process for obtaining the precipitate is as follows: the reaction solution is added to solvent B to precipitate the precipitate; the solvent B is at least one of ethanol, acetone, diethyl ether, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide.

14. The proton exchange membrane according to claim 12, characterized in that, The process of washing the precipitate is as follows: the precipitate is washed with water until it is neutral.

15. The proton exchange membrane according to claim 12, characterized in that, The drying conditions are: vacuum drying at 50-100℃ for 12-48 hours.

16. The proton exchange membrane according to claim 1, characterized in that, The mass ratio of taurine to fluoropolymer is (0.05-0.5):

1.

17. The proton exchange membrane according to claim 1, characterized in that, The molar ratio of lithium taurine to MgO is 1:(0.5-2).

18. A method for preparing an enhanced long-life proton exchange membrane for hydrogen production by water electrolysis according to any one of claims 1-17, characterized in that, include: Preparation of dispersion: Perfluorosulfonic acid resin and free radical quencher are added to a solvent, dissolved and mixed evenly to form a dispersion; Preparation of proton exchange membrane: Obtain a reinforcing material composed of ion exchange fibers, form a film on the reinforcing material with a dispersion, and obtain a proton exchange membrane after evaporation of the solvent.

19. The preparation method according to claim 18, characterized in that, The film-forming methods include, but are not limited to, solution casting, solution pouring, screen printing, scraping, spraying, or dipping.

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