Membrane electrode assembly and preparation method and application thereof

Abstract

The invention discloses a membrane electrode assembly and a preparation method and application thereof, and belongs to the technical field of new energy materials. According to the present invention, by using the super acid catalysis polymerization reaction, the piperidone and the different aromatic monomer compounds are synthesized into the aromatic polymer with the main chain not containing the ether bond and other unstable groups, such that the aromatic polymer can be simultaneously adopted as the diaphragm and the ionomer material; the membrane electrode can be applied to a methanol electrocatalytic oxidation coupling hydrogen production electrolytic tank and an alkaline water electrolytic tank. Through uniform compounding of the ionomer and the catalyst, non-uniform covering of the ionomer on the surfaces of catalyst particles is inhibited, the utilization rate of the catalyst is increased, and the catalyst layer and the diaphragm have good compatibility. The membrane electrode prepared by the method is stable in structure and low in cost, and has a good industrial application prospect.

Description

Technical Field

[0001] This invention belongs to the field of new energy materials technology, specifically relating to a membrane electrode assembly, its preparation method and application, and particularly to the application of an anion exchange membrane electrode assembly in methanol electrocatalytic oxidation coupled hydrogen production and alkaline water electrolysis hydrogen production devices. Background Technology

[0002] Energy refers to resources that can provide energy. As the cornerstone of human societal development, energy is the driving force behind human civilization's progress and is central to national security, economic development, people's livelihood, and public welfare. Among numerous new energy sources, hydrogen energy is a secondary energy source. Compared to other energy sources, hydrogen has a high calorific value and an energy density (140 MJ·kg⁻¹). -1 ) is petroleum (50 MJ·kg) -1 More than twice that of hydrogen. Furthermore, the combustion product of hydrogen is H2O, making it the most environmentally friendly energy source. In addition, hydrogen is an excellent energy storage medium for renewable and sustainable energy storage systems.

[0003] (1) Hydrogen and electricity can be efficiently converted into each other through technologies such as water electrolysis batteries and fuel cells.

[0004] (2) The generated hydrogen gas can be compressed, and the compressed hydrogen gas has a high energy density.

[0005] (3) Hydrogen energy can be applied on a large scale to the power grid power generation system.

[0006] Anion exchange membrane electrolyzers typically use pure water or a low-concentration alkaline solution as the electrolyte. The anion exchange membrane is sandwiched between the anode and cathode, and the electrolyte can be supplied to the cathode, anode, or both sides. H₂ and OH⁻ - OH is generated at the cathode. - O2 is generated by the migration of molecules through the membrane to the anode. Anion exchange membrane water electrolysis cells have the following main advantages:

[0007] (1) Using transition metal catalysts instead of noble metals (platinum group metals) as catalysts can achieve high activity while effectively reducing costs.

[0008] (2) Distilled water or low-concentration alkaline solution can be used instead of concentrated KOH solution as electrolyte to avoid the strong corrosiveness of concentrated alkali.

[0009] (3) The anion exchange membrane (such as a quaternary ammonium salt ion exchange group membrane) used in this water electrolysis device is more... The membrane is inexpensive, which significantly reduces input costs.

[0010] In traditional water electrolysis systems, the oxygen evolution reaction occurs at the anode, which, compared to the hydrogen evolution reaction at the cathode, is a complex four-electron transfer process with slow chemical reaction kinetics and a high theoretical potential. This significantly reduces the energy conversion efficiency of water electrolysis. Organic small molecule oxidation, as a feasible alternative, can replace the slow oxygen evolution reaction in water electrolysis. Coupling catalysis with organic small molecules not only reduces the theoretical voltage of the electrolyzer but also produces byproducts such as carboxylic acids or esters, which can be widely used as pharmaceutical intermediates in biofuels, fine chemicals, and the pharmaceutical industry. Methanol (CH3OH), as the simplest alcohol, is inexpensive, widely available, and has a low oxidation potential, making it an increasingly preferred anolyte for hydrogen production electrolyzers coupled with water electrolysis.

[0011] Currently, there is a lack of alkali-resistant and highly stable membrane electrode assemblies on the market. Poor compatibility between the catalyst layer and the membrane is the primary reason affecting the performance of alkaline electrolyzers. Using the same polymer for both the membrane and the ionomer helps improve compatibility. However, the polymers used in anion exchange membranes have higher molecular weights than those used in ionomers. This is because anion exchange membranes require good film-forming properties, high mechanical properties, and good alkali and heat resistance, which commercially available molecules cannot meet the requirements of ionomers. Unlike membranes, anion exchange membranes only need to ensure good mechanical strength and excellent hydroxide ion conductivity, requiring that gases generated at both the anode and cathode cannot pass through. Ionomers, on the other hand, operate in harsher conditions than membranes and require rapid gas removal. Therefore, the matching between a specific catalyst and a specific ionomer becomes particularly important. Summary of the Invention

[0012] To address the above-mentioned technical problems, the purpose of this invention is to provide a membrane electrode assembly, its preparation method, and its application, in order to solve problems such as incompatibility between ionomers and catalysts, low ionic conductivity, and swelling and shedding under alkaline electrolysis conditions.

[0013] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0014] The polyarylpiperidine ionomers prepared by this invention have good compatibility with catalysts, high ionic conductivity, low swelling ratio, high chemical stability, long lifespan, and are environmentally friendly. Moreover, their preparation method is simple and easy to implement and can be easily scaled up compared with existing methods.

[0015] The application of an anion exchange membrane electrode assembly in a methanol electrocatalytic oxidation coupled hydrogen production and alkaline water electrolysis hydrogen production device includes the following steps:

[0016] (1) Dissolve polyarylpiperidine powder in an organic solution at a certain mass fraction.

[0017] (2) The different types of ionomers prepared in step (1) are mixed with the catalyst in a certain proportion to prepare a catalyst dispersion. The catalyst is NiFeRu. Ultrasonic treatment is used to ensure uniform mixing.

[0018] (3) The catalyst dispersion is brushed onto the gas diffusion layer, wherein the anode uses nickel foam and the cathode uses carbon paper.

[0019] (4) A polymer organic solution was prepared by casting, coated onto a glass plate, and then processed to obtain an anion exchange membrane. After multiple soaking and ion exchange treatments, it was washed with ultrapure water and dried.

[0020] (5) Assemble the prepared anode and cathode gas diffusion layers and anion exchange membrane with the electrochemical device and test them.

[0021] In step (1), the organic solvent is one or both of ethanol and isopropanol. Preferably, the weight percentage of the ionomer is 2% to 15%, for example, it can be 10%, 11%, 12%, 13%, 14%, 15%, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0022] In step (2), the catalyst uses NiFeRu with the following metal ratios: 8:2:1, 7:2:1, 6:3:1, etc. When the catalyst is mixed with the ionomer, the ratio of catalyst to water is 0.1% to 5%, and the ratio of ionomer to catalyst is 2% to 20%. The mixing temperature is maintained at 30 to 50°C. Preferably, the catalyst uses NiFeRu in a ratio of 8:2:1, the ratio of catalyst to water is 3%, the ratio of ionomer to catalyst is 10%, and the mixing temperature is maintained at 40°C.

[0023] In step (3), the prepared catalyst dispersion is brushed onto the gas diffusion layer to form an electrode. The anode uses nickel foam as the gas diffusion layer (thickness 0.2–1 mm, porosity 95–98%), and the cathode uses carbon paper as the gas diffusion layer (thickness 0.2–1 mm, porosity 50–98%). The catalyst loading is 1–5 mg·cm³. -2 The brushing temperature is maintained at 50–70°C, and 8–15 brushes are applied to ensure uniform catalyst loading. Preferably, the catalyst loading is 3 mg·cm³. -2 The optimal brushing temperature is 60℃.

[0024] In step (4), anion exchange membranes are prepared by casting. 0.1 to 1 g of polymer is dissolved in 10 mL of organic solvent, including but not limited to DMSO, NMP, DMAc, and DMF.

[0025] The anion exchange membrane obtained in step (4) needs to be soaked in KCl or NaCl solution (60°C, 1M concentration, 4-5 times, 6-12h each time) and then soaked in KHCO3 or NaHCO3 solution (60°C, 1M concentration, 4-5 times, 6-12h each time).

[0026] The specific technical solution is as follows:

[0027] A membrane electrode assembly includes a polymer membrane and a catalyst layer located on or attached to both surfaces of the polymer membrane, the catalyst layer comprising an ionomer and a catalyst;

[0028] The polymer and ionomer in the polymer film respectively include or are any one or more of the following general formulas of polyarylpiperidine polymers:

[0029]

[0030] R represents any one or more of the four groups on the right, where * represents the linking site.

[0031] Furthermore, the ionomer used is a polyarylepiperidine polymer with a number average molecular weight of 5,000 to 10,000 and a polymer molecular weight dispersibility index of 1 to 3.

[0032] The polymer membrane is a dense membrane made of polyarylepiperidine polymer with a number average molecular weight of 10,000 to 80,000, a polymer molecular weight dispersibility index of 1 to 3, and a thickness of 20 to 90 μm.

[0033] Preferably, the R values ​​are the same in the molecular structure of the polymer or ionomer.

[0034] Furthermore, a gas diffusion layer is respectively provided on one or two catalyst layers away from the surface of the polymer film;

[0035] The catalyst in the catalyst layer is an inorganic catalyst.

[0036] Furthermore, the catalyst is NiFeRu; wherein the molar ratio of Ni / Fe is 5:1-1:1, the molar ratio of Fe / Ru is 4:1-2:1, and the catalyst is a layered material with a surface area of ​​2000-10000 square nanometers and a thickness of 5-20 nanometers.

[0037] Furthermore, the polyarylpiperidine polymer is obtained by condensation polymerization of piperidinone and aromatic monomers under the catalysis of trifluoroacetic acid and trifluoromethanesulfonic acid to obtain an unquaternized polymer; the polymerization temperature is 0-5℃, and polymers with different molecular weights are obtained by controlling the reaction time;

[0038] The piperidine functional groups of the polymer are then modified by iodomethane quaternization reaction to obtain the polyarylpiperidine polymer having quaternized piperidine onon groups;

[0039] The piperidinone is 1-methyl-4-piperidinone;

[0040] The aromatic monomers are terphenyl, diphenyl, 2,7-dimethylfluorene, and 1,2-diphenylethane.

[0041] Furthermore, the polymer film preparation method is as follows:

[0042] 1) An organic solution of polyarylpiperidine polymer was cast onto a plate using a casting method.

[0043] The polymer organic solution is prepared by dissolving a polyarylpiperidine polymer in an organic solvent; its concentration in the organic solution is 0.05–0.2 g·mL. -1 Organic solvents include one or more of DMSO, DMC, NMP, and DMF;

[0044] 2) After casting, dry to evaporate the organic solvent. The drying temperature is 50-80℃ and the drying time is 24-48h.

[0045] 3) After drying, remove the plate with the polymer film and soak it in water for 3-5 hours to remove the film;

[0046] 4) Immerse the removed membrane in 1-3M KCl and / or NaCl solution at 50-80℃ for a total of 4-7 times, each time for 6-12 hours; then immerse the membrane again in 1-3M KHCO3 and / or NaHCO3 solution at 50-80℃ for a total of 4-7 times, each time for 6-12 hours; finally wash with water 2-3 times and air dry at room temperature to obtain the polymer membrane.

[0047] A method for fabricating a membrane electrode assembly includes the following steps:

[0048] 1) The polyarylpiperidine polymer is soaked in 1-3M KCl and / or NaCl solution at 50-80℃ for a total of 4-7 times, each time for 6-12 hours; then soaked in 1-3M KHCO3 and / or NaHCO3 solution at 50-80℃ for a total of 4-7 times, each time for 6-12 hours; finally washed with water 2-3 times and air-dried at room temperature to obtain the ionomer;

[0049] 2) Dissolve the ionomer in an organic solvent to obtain an ionomer solution; the polymer mass fraction is 1-10%; the organic solvent includes one or more of ethanol, isopropanol, and dimethyl sulfoxide;

[0050] The catalyst and water are mixed to prepare a catalyst dispersion; wherein the catalyst concentration (based on the mass ratio of catalyst to water) is 2% to 5%.

[0051] The ionomer solution and the catalyst dispersion are mixed to obtain the catalyst ionomer dispersion; the ratio of ionomer solution to catalyst dispersion (based on the mass ratio of ionomer to catalyst) is 5% to 20%; the mixing temperature is 30 to 50℃.

[0052] 3) The prepared catalyst ionomer dispersion was brushed onto one side of the gas diffusion layer of both the anode and cathode to form gas diffusion electrodes. Nickel foam was used as the gas diffusion layer for the anode, and carbon paper was used as the gas diffusion layer for the cathode. The catalyst loading was 1–5 mg·cm³. -2 The brushing temperature is maintained at 50-70℃, and the brushing number is 8-15 times to ensure uniform catalyst loading; gas diffusion electrodes for anode and cathode are obtained.

[0053] The thickness of the nickel foam is 0.2–1 mm, and the porosity is 50–98%; the thickness of the carbon paper is 0.2–1 mm, and the porosity is 50–98%.

[0054] 4) Stack the cathode gas diffusion electrode, the anion exchange membrane, and the anode gas diffusion electrode, and brush the catalyst ionomer dispersion of the cathode gas diffusion electrode and the anode gas diffusion electrode onto the anion exchange membrane side by side, and press at room temperature or hot on both sides of the anion exchange membrane to obtain the membrane electrode assembly.

[0055] The ambient temperature pressure is 0.1–5 MPa, and the ambient temperature pressure duration is 0.5–30 min; the hot pressure is 0.1–5 MPa, the hot pressure temperature is 60–100 °C, and the hot pressure duration is 10 s–1 min.

[0056] An application of an anion exchange membrane electrode assembly, wherein the membrane electrode assembly is an anion exchange membrane electrode assembly, which can be used as a membrane electrode in the process of methanol electrocatalytic oxidation coupled with hydrogen production or alkaline water electrolysis for hydrogen production.

[0057] 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.

[0058] The core of the novel anion exchange membrane electrode assembly of this invention lies in the preparation of a catalyst and ionomer dispersion. The dispersion is brushed onto the gas diffusion layer using a specialized brush, which increases the catalyst loading, ensures uniform catalyst distribution, improves gas diffusion performance, and enhances electrode stability and durability. This not only improves catalytic efficiency and reaction uniformity but also extends electrode lifespan, thereby improving the overall performance and reliability of alkaline water electrolysis devices. The novel alkaline anion exchange membrane electrode assembly of this invention is low-cost, possesses good catalyst loading and excellent ion exchange capacity, and can maintain a long lifespan even under the alkaline concentration environment required for anion exchange membrane water electrolysis (AEMWE).

[0059] Compared with the prior art, the present invention has the following beneficial effects:

[0060] 1) This invention utilizes organic polymer materials such as polyarylepiperidine and achieves efficient ion exchange and catalytic reaction through multi-step processing and catalyst selection, thereby improving the efficiency of hydrogen production by water electrolysis and the electrocatalytic coupling of methanol to produce formic acid.

[0061] 2) By adjusting the ratio of different polyarylepiperidine polymers, the content of ionomers, and the selection and proportion of catalysts, the electrode performance can be flexibly adjusted to adapt to different process conditions and application requirements.

[0062] 3) By controlling the synthesis conditions and ion exchange process of polyarylepiperidine polymer, this invention can precisely regulate the structure and performance of membrane electrode assembly, thereby achieving precise control and optimization of the electrolysis process.

[0063] 4) This invention selects a specific catalyst (NiFeRu) and a polyarylpiperidine ionomer. In their specific combined structure, the lone pair electrons can form coordinate bonds with the metal center, enhancing the combination between the ionomer and the catalyst. This combination may be very critical for electron transfer and catalytic stability in the electrocatalytic process.

[0064] 5) This invention uses high-performance materials such as carbon paper and nickel foam as the gas diffusion layer, as well as an anion exchange membrane that has undergone multiple ion exchange treatments, which makes the membrane electrode assembly have high stability and corrosion resistance, and extends the service life of the device.

[0065] 6) The membrane electrode assembly prepared by this invention has low cost and high stability, meets the needs of large-scale applications, and shows good prospects. Attached Figure Description

[0066] Figure 1 Polarization curves for methanol oxidation coupling hydrogen production performance testing of the membrane electrode assembly prepared in Example 1.

[0067] Figure 2The polarization curves are used to test the alkaline water electrolysis hydrogen production performance of the membrane electrode assembly prepared in Example 1. Detailed Implementation

[0068] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the invention. Unless otherwise specified, the examples are conducted under conventional experimental conditions. Furthermore, for those skilled in the art, various modifications or improvements to the material composition and dosage in these embodiments without departing from the spirit and scope of the present invention are all within the scope of protection claimed by the present invention.

[0069] The application of quaternized polyarylepiperidine polymers in methanol electrocatalytic oxidation coupled hydrogen production electrolyzers and alkaline water electrolysis hydrogen production electrolyzers, as described in the following embodiments of the present invention, includes the following features:

[0070] (1) The zero-gap electrolytic cell consists of bipolar plates with serpentine paths, U-shaped (hollow rectangular ring) fluororubber gaskets, and membrane electrode assemblies. The bipolar plates are platinum-plated titanium plates, and the fluororubber thickness is 150–300 μm (200 μm in this case). During battery assembly, the membrane electrode assembly is sandwiched between the fluororubber gasket and the bipolar plates, forming a stacked structure of bipolar plates, fluororubber gaskets, membrane electrode assembly, fluororubber gaskets, and bipolar plates. The active area is equal to the hollow area of ​​the U-shaped fluororubber gasket and also equal to the catalyst coating area, which is 2 cm × 2 cm. When the electrolytic cell is working, the electrolyte flows into the bipolar plates from the serpentine inlets and through the U-shaped fluororubber gaskets and the membrane electrode catalyst layer, and finally flows out from the serpentine outlets of the two bipolar plates.

[0071] (2) The membrane electrode assembly consists of a diaphragm and a gas diffusion electrode (prepared by the following examples or comparative examples), with nickel foam and carbon paper as gas diffusion layers for the anode and cathode, respectively.

[0072] (3) The electrolytic performance of the ionomer and polymer membrane was evaluated using the alkaline electrolytic cell described in (1). During the test, the electrolyte in the methanol catalytic electrolysis hydrogen production electrolytic cell was 10% methanol by mass, and the electrolyte in the water electrolysis hydrogen production electrolytic cell was 1 MkOH. The electrolyte flow rate was 3 mL / min. -1 The electrolysis temperature was controlled at 60℃. The current density of the electrolytic cell within the voltage range of 1.1 to 2V was recorded using an Arbin charge-discharge instrument.

[0073] Example 1

[0074] (I) A method for synthesizing polyarylpiperidine polymers, comprising the following steps:

[0075] In two three-necked flasks (one for preparing the ionomer and the other for preparing the polyarylpiperidine polymer for the membrane material), each equipped with a mechanical stirrer, 0.1 mol of 1-methyl-4-piperidinone and 0.1 mol of the aromatic monomer terphenyl were dispersed in 150 mL of dichloromethane solvent, respectively. After the reactants (1-methyl-4-piperidinone and terphenyl) were completely dissolved, the system was cooled to 0–5 °C. 5 mL of trifluoroacetic acid (TFA) and 1 mL of trifluoromethanesulfonic acid (TFSA) were slowly added dropwise to the flask through a constant-pressure dropping funnel. The mixture was then stirred continuously at this temperature for 6 h to obtain the ionomer polymer, and then stirred for 12 h to obtain the polyarylpiperidine polymer for the membrane material. After stirring, the resulting dark blue viscous solution was slowly poured into a 1 mol·L⁻¹ liquid. -1 A white fibrous solid was obtained in a sodium carbonate solution. The solid was filtered, dried, and crushed into a white powder. It was then washed repeatedly with deionized water and ethanol 10 times to thoroughly remove impurities. Finally, the powder was filtered and dried in a vacuum oven at 120°C for 24 hours to remove residual moisture from the polymer. This yielded a non-quaternized polyarylpiperidine polymer (number average molecular weight 20,000, molecular weight dispersion index 1–3) with a 1:1 ratio of piperidine groups to terphenyl groups in the repeating molecular unit, and a non-quaternized polyarylpiperidine ionomer polymer (number average molecular weight 6,000, molecular weight dispersion index 1–3).

[0076] (II) Preparation of membrane electrode assembly:

[0077] Step 1: Preparation of ionomer solution:

[0078] 1) In a 50 mL brown round-bottom flask, 1 g of unquaternized polyarylpiperidine ionomer was dispersed in 20 mL of dimethyl sulfoxide, and 1.5 mL of methylating agent iodomethane was added and reacted in the dark for 24 h. The resulting product was washed 4 times with diethyl ether and dried at 70 °C for 48 h. After drying, quaternized polyarylpiperidine ionomer was obtained.

[0079] 2) The quaternized polyarylpiperidine ionomer polymer obtained in 1) was ion-exchanged 6 times in 1 L 1M KCl solution at 80 °C for 6 h each time, then washed and soaked in deionized water to remove residual KCl, and obtained polymer powder in chloride ion form.

[0080] 3) The polymer powder obtained in 2) was subjected to ion exchange six times in 1 L 1M KHCO3 solution at 60℃, each time for 6 hours, and then soaked, washed and dried in deionized water.

[0081] 4) Dissolve the powder obtained in 3) in an organic solution according to the mass fraction, wherein the organic solvent is ethanol and the polymer mass fraction is 5%, to obtain an ionomer solution.

[0082] Step 2: Synthesis of NiFeRu catalyst: NiSO4·6H2O, FeSO4·7H2O, and RuCl3·xH2O were dissolved in deionized water at a molar ratio of 8:2:1 to form a 10 mL precursor solution of the metal salt (with a Ni salt concentration of 0.1 mol / L). The solution was stirred for 30 minutes at 500 rpm in an ice-water bath using a magnetic stirrer. Simultaneously, a 10 mg·mL⁻¹ catalyst was prepared according to the specified ratio. -1 The KBH4 deionized aqueous solution was uniformly dispersed in a room temperature ultrasonic water bath, and then cooled by stirring at 500 rpm in an ice-water bath. Next, the above metal salt precursor solution was rapidly added to 40 mL (or 30 to 50 mL) of KBH4 solution, and stirring was continued for 10 minutes. Stirring was stopped, and the solution was allowed to stand at room temperature for 2 hours. The solid catalyst was collected. The catalyst was ultrasonically cleaned with deionized water and then dispersed in deionized water to obtain a layered dispersion of NiFeRu catalyst with a surface area of ​​0.01 to 0.04 square micrometers and a thickness of 5 to 20 nanometers.

[0083] Step 3: Mix the ionomer solution obtained in Step 1 with the catalyst dispersion obtained in Step 2 to prepare a catalyst ionomer dispersion. The catalyst is NiFeRu, where the molar ratio of Ni:Fe:Ru is 8:2:1. The catalyst concentration (based on the mass ratio of catalyst to water) is 3%, and the mixing ratio of the ionomer solution and the catalyst dispersion (based on the mass ratio of ionomer to catalyst) is 10%. The mixing temperature for preparing the catalyst ionomer dispersion is 50℃. To ensure uniform mixing, the dispersion is ultrasonically treated using an ultrasonic instrument to obtain the catalyst ionomer dispersion.

[0084] Step 4: Preparation of anion exchange membrane:

[0085] 1) 1 g of unquaternized polyarylpiperidine polymer was dispersed in 20 mL of DMSO. Then, 2 g of iodomethane was added to the system, and the solution was stirred at 25 °C for 12 h. After stirring, the resulting viscous yellow solution was added dropwise to diethyl ether and washed repeatedly four times to thoroughly remove impurities. Finally, the yellow solid was filtered, washed with diethyl ether, and dried in a vacuum oven at 60 °C for 24 h to remove residual organic solvents, yielding the quaternized polyarylpiperidine polymer.

[0086] 2) A quaternized polyarylpiperidine polymer organic solution was cast onto a flat plate (a glass plate was used in this embodiment) using a casting method. The concentration of the organic solution was 0.1 g·mL⁻¹. -1The organic solvent was DMSO. After casting, the organic solvent was evaporated by drying at 60℃ for 24 hours. After drying, the glass plate with the polymer membrane was removed and immersed in ultrapure water for 5 hours, then the membrane was removed. The removed membrane was immersed in 1L of 1M KCl solution at 80℃ for 5 times, 12 hours each time. The treated membrane was then immersed in 1L of 1M KHCO3 solution at 80℃ for 5 times, 12 hours each time. Finally, it was washed 3 times with ultrapure water and air-dried at room temperature to obtain an anion exchange membrane with a thickness of 50μm.

[0087] Step 5: Fabrication of the membrane electrode assembly:

[0088] The catalyst ionomer dispersion prepared in step 3 was brushed onto one side of the gas diffusion layer to form an electrode. The anode used sheet-like nickel foam as the gas diffusion layer (1 mm thick, 90% porosity), and the cathode used carbon paper as the gas diffusion layer (1 mm thick, 90% porosity). The catalyst loading was 3 mg·cm³. -2 The brushing temperature was maintained at 60℃, and the coating was applied 12 times to ensure uniform catalyst loading. Subsequently, the cathode gas diffusion electrode and the anode gas diffusion electrode were hot-pressed onto both sides of the dry anion exchange membrane, so that the catalyst ionomer dispersion of the cathode gas diffusion electrode and the anode gas diffusion electrode faced the anion exchange membrane. The hot-pressing temperature (4MPa) was 80℃, and the hot-pressing time was 1min.

[0089] Step 6: The membrane electrode assembly prepared in Step 5 is applied in a methanol electrocatalytic coupling hydrogen production electrolyzer, where 10% methanol (by mass) is used as the anolyte, 2M KOH solution is used as the catholyte, the electrolysis temperature is 60℃, and the electrolyte flow rate is 3 mL / min. -1 The polarization curve of the battery was measured (scanned from 0.8V to 2V at a scan rate of 10mV·s). -1 The effective active area of ​​each battery is 4 cm². 2 The membrane electrode assembly is installed between the fluororubber gaskets of the anode and cathode. The bipolar plates clamp the gaskets and membrane electrode assembly on the outermost sides of the battery. The battery tightening torque is 4 N·m.

[0090] Step 7: The membrane electrode assembly prepared in Step 5 is applied to alkaline water electrolysis for hydrogen production. A 1M KOH solution is used as the electrolyte, the electrolysis temperature is 60℃, and the electrolyte flow rate is 3 mL / min. -1 The polarization curve of the battery was measured (scanned from 0.8V to 2V at a scan rate of 10mV·s). -1 The effective active area of ​​each battery is 4 cm². 2The membrane electrode assembly is installed between the fluororubber gaskets of the anode and cathode. The bipolar plates clamp the gaskets and membrane electrode assembly on the outermost sides of the battery. The battery tightening torque is 4 N·m.

[0091] Example 2: [Changing the polymer structure]

[0092] The difference from Example 1 is that: (i) the main chain of the anion exchange membrane and the ionomer polymer is selected with an equimolar amount of biphenyl instead of terphenyl in Example 1, and the remaining steps (process and conditions) are the same as in Example 1. Unquaternized polyarylpiperidine anion exchange membrane polymer (number average molecular weight 16000, polymer molecular weight dispersion index 1-3) and unquaternized polyarylpiperidine ionomer polymer (number average molecular weight 4500, polymer molecular weight dispersion index 1-3) with a 1:1 ratio of piperidine groups to biphenyl groups in the molecular repeating unit were obtained.

[0093] The remaining steps (process and conditions) are the same as in Example 1.

[0094] Example 3: [Changing the polymer structure]

[0095] The difference from Example 1 is that: (i) the main chain of the anion exchange membrane and the ionomer polymer uses equimolar amounts of 2,7-dimethylfluorene instead of terphenyl in Example 1, and the remaining steps (process and conditions) are the same as in Example 1. Unquaternized polyarylpiperidine anion exchange membrane polymers (number average molecular weight 18000, polymer molecular weight dispersion index 1-3) and unquaternized polyarylpiperidine ionomer polymers (number average molecular weight 5500, polymer molecular weight dispersion index 1-3) with a 1:1 ratio of piperidine groups to 2,7-dimethylfluorene in the molecular repeating unit were obtained.

[0096] The remaining steps (process and conditions) are the same as in Example 1.

[0097] Example 4: [Changing the polymer structure]

[0098] The difference from Example 1 is that: (i) the main chain of the anion exchange membrane and the ionomer polymer is selected with equimolar amounts of 1,2-diphenylethane instead of terphenyl in Example 1, and the remaining steps (process and conditions) are the same as in Example 1. Unquaternized polyarylpiperidine anion exchange membrane polymer (number average molecular weight 17000, polymer molecular weight dispersion index 1-3) and unquaternized polyarylpiperidine ionomer polymer (number average molecular weight 5000, polymer molecular weight dispersion index 1-3) with a molecular repeating unit piperidine group to 1,2-diphenylethane ratio of 1:1 were obtained.

[0099] The remaining steps (process and conditions) are the same as in Example 1.

[0100] Example 5: [Changing the molecular weight of polyarylpiperidine anion exchange membrane polymer]

[0101] The difference from Example 1 is that: in step (I), the reaction stirring time of the polyarylpiperidine polymer used to prepare the anion exchange membrane was 24 hours, and the reaction stirring time of the polyarylpiperidine ionomer used to prepare the ionomer was 4 hours. The remaining steps (process and conditions) were the same as in Example 1. Unquaternized polyarylpiperidine anion exchange membrane polymers (number average molecular weight 80,000, polymer molecular weight dispersion index 1-3) and unquaternized polyarylpiperidine ionomer polymers (number average molecular weight 5,000, polymer molecular weight dispersion index 1-3) with a 1:1 ratio of piperidine groups to terphenyl groups in the molecular repeating unit were obtained.

[0102] The remaining steps (process and conditions) are the same as in Example 1.

[0103] Example 6: [Changing the molecular weight of polyarylpiperidine anion exchange membrane polymer]

[0104] The difference from Example 1 is that: in step (I), the reaction stirring time of the polyarylpiperidine polymer used to prepare the anion exchange membrane was 8 hours, and the reaction stirring time of the polyarylpiperidine ionomer used to prepare the ionomer was 8 hours. The remaining steps (process and conditions) were the same as in Example 1. Unquaternized polyarylpiperidine anion exchange membrane polymers (number average molecular weight 10000, polymer molecular weight dispersion index 1-3) and unquaternized polyarylpiperidine ionomer polymers (number average molecular weight 10000, polymer molecular weight dispersion index 1-3) with a 1:1 ratio of piperidine groups to terphenyl groups in the molecular repeating unit were obtained.

[0105] The remaining steps (process and conditions) are the same as in Example 1.

[0106] Example 7: [Changing the proportion of catalyst components]

[0107] The difference from Example 1 is that:

[0108] (II) Step 2 is changed to: Synthesis of NiFeRu catalyst: NiSO4·6H2O, FeSO4·7H2O and RuCl3·xH2O are dissolved in deionized water in a molar ratio of 6:3:1;

[0109] (II) Step 3 is modified as follows: The ionomer solution obtained in Step 1 is mixed with the catalyst dispersion to prepare a catalyst ionomer dispersion. The catalyst is NiFeRu, where the molar ratio of Ni:Fe:Ru is 6:3:1. The catalyst concentration (the ratio of catalyst to water) is 3%, and the ratio of ionomer solution to catalyst ionomer dispersion (the ratio of ionomer to catalyst) is 10%. The mixing temperature for preparing the catalyst ionomer dispersion is 50℃. To ensure uniform mixing, the dispersion is ultrasonically treated using an ultrasonic instrument.

[0110] The remaining steps (process and conditions) are the same as in Example 1.

[0111] Example 8: [Changing the ratio of catalyst to ionomer]

[0112] The difference from Example 1 is that:

[0113] (ii) Step 3 is modified to: other operations are the same as in step 3. The mixing ratio of ionomer solution and catalyst dispersion (based on the mass ratio of ionomer to catalyst) is 5%.

[0114] The remaining steps (process and conditions) are the same as in Example 1.

[0115] Example 9: [Changing the ratio of catalyst to ionomer]

[0116] The difference from Example 1 is that:

[0117] (ii) Step 3 is modified as follows: Other operations are the same as in Step 3. The mixing ratio of the ionomer solution and the catalyst dispersion (based on the mass ratio of ionomer to catalyst) is 20%.

[0118] The remaining steps (process and conditions) are the same as in Example 1.

[0119] Example 10: [Changing the thickness of the anion exchange membrane]

[0120] The difference from Example 1 is that:

[0121] (ii) In step 4, step 2) is changed to: all other operations are the same as in step 4, step 2). The concentration of the organic solvent is 0.05 g·mL. -1 The organic solvent was DMSO, the evaporation temperature was 60℃, and the drying time was 24h. An anion exchange membrane with a thickness of 20μm was obtained.

[0122] The remaining steps (process and conditions) are the same as in Example 1.

[0123] Example 11: [Changing the thickness of the anion exchange membrane]

[0124] The difference from Example 1 is that:

[0125] (ii) In step 4, step 2) is changed to: all other operations are the same as in step 4, step 2). The concentration of the organic solvent is 0.2 g·mL. -1 The organic solvent was DMSO, the evaporation temperature was 60℃, and the drying time was 24h. An anion exchange membrane with a thickness of 90μm was obtained.

[0126] The remaining steps (process and conditions) are the same as in Example 1.

[0127] Comparative Example 1: [Catalyst Replacement]

[0128] The difference from Example 1 is that:

[0129] (ii) Step 3 is changed to: use deionized water to ultrasonically clean the pure Ni powder (particle size of about 200 nm), disperse it in deionized water, and obtain a pure Ni powder catalyst dispersion.

[0130] The ionomer solution obtained in step 1 was mixed with the pure Ni powder catalyst dispersion to prepare a catalyst ionomer dispersion. The catalyst concentration (catalyst to water ratio) was 3%, and the ratio of the ionomer solution to the catalyst ionomer dispersion (ionomer to catalyst ratio) was 10%. The mixing temperature for preparing the catalyst ionomer dispersion was 50℃. To ensure uniform mixing, the dispersion was ultrasonically treated.

[0131] The remaining steps (process and conditions) are the same as in Example 1.

[0132] Comparative Example 2: [Whether the ionomer is quaternized]

[0133] The difference from Example 1 is that:

[0134] (ii) Step 1 is changed to: In a 50mL brown round-bottom flask, 1g of polymer is dispersed in 20mL of dimethyl sulfoxide and stirred in the dark for 24h. The polymer is then washed 6 times with diethyl ether and dried to obtain polyarylpiperidine ionomer polymer. This polyarylpiperidine ionomer polymer has not undergone quaternization treatment.

[0135] The remaining steps (process and conditions) are the same as in Example 1.

[0136] Comparative Example 3: [Whether the anion exchange membrane is quaternized]

[0137] The difference from Example 1 is that:

[0138] (ii) Step 4 is changed to:

[0139] Anion exchange membrane preparation method: An unquaternized polyarylpiperidine polymer organic solution was cast onto a glass plate using a casting method. The concentration of the organic solution was 0.1 g·mL⁻¹.-1 The organic solvent used was DMSO. After casting, the organic solvent was evaporated by drying at 60℃ for 24 hours. After drying, the glass plate was removed and immersed in ultrapure water for 5 hours, then the membrane was removed. The removed membrane was immersed in 1M KCl solution at 80℃ for 5 times, 12 hours each time. The treated membrane was then immersed in 1M KHCO3 solution at 80℃ for 5 times, 12 hours each time. Finally, it was washed 3 times with ultrapure water and air-dried at room temperature to obtain an anion exchange membrane with a thickness of 50 μm.

[0140] The remaining steps (process and conditions) are the same as in Example 1.

[0141] Comparative Example 4: [Changing the Polymer Structure]

[0142] The difference from Example 1 is that:

[0143] (i) The main chains of the anion exchange membrane polymer and the ionomer polymer are selected to have an equal molar amount of benzene rings instead of terphenyl in Example 1, and the remaining steps (process and conditions) are the same as in Example 1.

[0144] The remaining steps (process and conditions) are the same as in Example 1.

[0145] Comparative Example 5: [Changing the Polymer Structure]

[0146] The difference from Example 1 is that:

[0147] (a) The main chain of the anion exchange polymer membrane and the ionomer polymer is selected to be equimolarly 1,4-diphenylbutane instead of terphenyl in Example 1, and the remaining steps (process and conditions) are the same as in Example 1.

[0148] The remaining steps (process and conditions) are the same as in Example 1.

[0149] Comparative Example 6: [Replacing the Anion Exchange Membrane Material]

[0150] The difference from Example 1 is that:

[0151] (ii) Step 4 is changed to:

[0152] Anion exchange membrane preparation method: A commercial FUMA membrane with a thickness of 50-80 μm was selected. The purchased membrane was immersed in 1 M K HCO3 solution at a temperature of 60 °C for 5 times, each time for 12 hours. Finally, it was washed 3 times with ultrapure water and air-dried at room temperature to obtain the anion exchange membrane.

[0153] The remaining steps (process and conditions) are the same as in Example 1.

[0154] Comparative Example 7: [Without using ionomers]

[0155] The difference from Example 1 is that:

[0156] (II) In step 3 of the preparation of the dispersion, no ionomer is added. Specifically, water and the catalyst are mixed to prepare a catalyst dispersion. The catalyst is NiFeRu, with a Ni:Fe:Ru ratio of 8:2:1. The catalyst concentration (the ratio of catalyst to water) is 3%, and the mixing temperature for preparing the catalyst dispersion is 50℃. To ensure uniform mixing, the dispersion is ultrasonically treated.

[0157] The remaining steps are the same as those in Example 1 (process and conditions).

[0158] Comparative Example 8: [No catalyst used]

[0159] The difference from Example 1 is that:

[0160] (ii) In step 3 of the preparation of the dispersion, no catalyst is added. The specific steps are as follows: the ionomer solution obtained in step 1 is mixed with water, and the mass percentage of the ionomer is 10%. In order to make the solution uniformly mixed, the dispersion is ultrasonically treated using an ultrasonic instrument.

[0161] The remaining steps are the same as those in Example 1 (process and conditions).

[0162] Comparative Example 9: [Catalyst Modification]

[0163] The difference from Example 1 is that:

[0164] (II) Step 2 is changed to: Synthesis of NiFe catalyst: NiSO4·6H2O and FeSO4·7H2O are dissolved in deionized water at a molar ratio of 8:2;

[0165] (II) Step 3 is modified as follows: The ionomer solution obtained in Step 1 is mixed with the catalyst dispersion obtained in Step 2 to prepare a catalyst ionomer dispersion. The catalyst is NiFe, with a Ni:Fe ratio of 8:2. The catalyst concentration (the ratio of catalyst to water) is 3%, and the ratio of ionomer solution to catalyst dispersion (the ratio of ionomer to catalyst) is 10%. The mixing temperature for preparing the catalyst ionomer dispersion is 50℃. To ensure uniform mixing, the dispersion is ultrasonically treated using an ultrasonic instrument.

[0166] The remaining steps are the same as those in Example 1 (process and conditions).

[0167] Comparative Example 10: [Catalyst Concentration Changed]

[0168] The difference from Example 1 is that:

[0169] (II) Step 3 is modified as follows: The ionomer solution obtained in Step 1 is mixed with the catalyst to prepare a catalyst ionomer dispersion. The catalyst is NiFeRu, where the molar ratio of Ni:Fe:Ru is 8:2:1. The catalyst concentration (the ratio of catalyst to water) is 3%, and the ratio of ionomer solution to catalyst dispersion (the ratio of ionomer to catalyst) is 2%. The mixing temperature for preparing the catalyst ionomer dispersion is 50℃. To ensure uniform mixing, the dispersion is ultrasonically treated using an ultrasonic instrument.

[0170] The remaining steps are the same as those in Example 1 (process and conditions).

[0171] Comparative Example 11: [Changing the concentration of ionomers]

[0172] The difference from Example 1 is that:

[0173] (II) Step 3 is modified as follows: The ionomer solution obtained in Step 1 is mixed with the catalyst to prepare a catalyst ionomer dispersion. The catalyst is NiFeRu, where the molar ratio of Ni:Fe:Ru is 8:2:1. The catalyst concentration (the ratio of catalyst to water) is 3%, and the ratio of ionomer solution to catalyst dispersion (the ratio of ionomer to catalyst) is 30%. The mixing temperature for preparing the catalyst ionomer dispersion is 50℃. To ensure uniform mixing, the dispersion is ultrasonically treated using an ultrasonic instrument.

[0174] The remaining steps are the same as those in Example 1 (process and conditions).

[0175] Comparative Example 12: [Changing the molecular weight of the polyarylpiperidine anion exchange membrane polymer]

[0176] The difference from Example 1 is that: in step (I), the reaction stirring time of the polyarylpiperidine polymer used to prepare the anion exchange membrane was 12 hours, and the reaction stirring time of the polyarylpiperidine ionomer used to prepare the ionomer was 3 hours. The remaining steps (process and conditions) were the same as in Example 1. Unquaternized polyarylpiperidine anion exchange membrane polymers (number average molecular weight 20,000, polymer molecular weight dispersion index 1-3) and unquaternized polyarylpiperidine ionomer polymers (number average molecular weight 2,000, polymer molecular weight dispersion index 1-3) with a 1:1 ratio of piperidine groups to terphenyl groups in the molecular repeating unit were obtained.

[0177] The remaining steps (process and conditions) are the same as in Example 1.

[0178] Comparative Example 13: [Changing the molecular weight of the polyarylpiperidine anion exchange membrane polymer]

[0179] The difference from Example 1 is that: in step (I), the reaction stirring time of the polyarylpiperidine polymer used to prepare the anion exchange membrane was 12 hours, and the reaction stirring time of the polyarylpiperidine ionomer used to prepare the ionomer was 12 hours; the remaining steps (process and conditions) were the same as in Example 1. Unquaternized polyarylpiperidine anion exchange membrane polymers (number average molecular weight 20,000, polymer molecular weight dispersion index 1-3) and unquaternized polyarylpiperidine ionomer polymers (number average molecular weight 20,000, polymer molecular weight dispersion index 1-3) with a 1:1 ratio of piperidine groups to terphenyl groups in the molecular repeating unit were obtained.

[0180] The remaining steps (process and conditions) are the same as in Example 1.

[0181] Comparative Example 14: [Changing the molecular weight of the polyarylpiperidine anion exchange membrane polymer]

[0182] The difference from Example 1 is that: in step (I), the reaction stirring time of the polyarylpiperidine polymer used to prepare the anion exchange membrane was 4 hours, and the reaction stirring time of the polyarylpiperidine ionomer used to prepare the ionomer was 4 hours. The remaining steps (process and conditions) were the same as in Example 1. Unquaternized polyarylpiperidine anion exchange membrane polymers (number average molecular weight 5000, polymer molecular weight dispersion index 1-3) and unquaternized polyarylpiperidine ionomer polymers (number average molecular weight 5000, polymer molecular weight dispersion index 1-3) with a 1:1 ratio of piperidine groups to terphenyl groups in the molecular repeating unit were obtained.

[0183] The remaining steps (process and conditions) are the same as in Example 1.

[0184] Comparative Example 15: [Changing the molecular weight of the polyarylpiperidine anion exchange membrane polymer]

[0185] The difference from Example 1 is that: in step (I), the reaction stirring time of the polyarylpiperidine polymer used to prepare the anion exchange membrane was 26 hours, and the reaction stirring time of the polyarylpiperidine ionomer used to prepare the ionomer was 4 hours. The remaining steps (process and conditions) were the same as in Example 1. Unquaternized polyarylpiperidine anion exchange membrane polymers (number average molecular weight 100,000, polymer molecular weight dispersion index 1-3) and unquaternized polyarylpiperidine ionomer polymers (number average molecular weight 5,000, polymer molecular weight dispersion index 1-3) with a 1:1 ratio of piperidine groups to terphenyl groups in the molecular repeating unit were obtained.

[0186] The remaining steps (process and conditions) are the same as in Example 1.

[0187] Comparative Example 16: [Changing the thickness of the anion exchange membrane]

[0188] The difference from Example 1 is that:

[0189] (ii) In step 4, step 2) is changed to: all other operations are the same as in step 4, step 2). The concentration of the organic solvent is 0.01 g·mL. -1 The organic solvent was DMSO, the evaporation temperature was 60℃, and the drying time was 24h. An anion exchange membrane with a thickness of 10μm was obtained.

[0190] The remaining steps (process and conditions) are the same as in Example 1.

[0191] Comparative Example 17: [Changing the thickness of the anion exchange membrane]

[0192] The difference from Example 1 is that:

[0193] (ii) In step 4, 2) is changed to: Other operations are the same as in step 4, 2). The concentration of the organic solvent is 1 g·mL. -1 The organic solvent was DMSO, the evaporation temperature was 60℃, and the drying time was 24h. An anion exchange membrane with a thickness of 150μm was obtained.

[0194] The remaining steps (process and conditions) are the same as in Example 1.

[0195] Table 1:

[0196]

[0197]

[0198]

[0199] The performance test results of the membrane electrode assemblies obtained in the above embodiments and comparative examples in a methanol electrocatalytic oxidation coupled hydrogen production electrolyzer and an alkaline water electrolyzer are listed in Table 2 (current density corresponding to 1.8V).

[0200] Table 2:

[0201]

[0202]

[0203] The data from Examples 1-4 and Comparative Examples 4-5 show that the anion exchange membranes and ionomers prepared with different main chains affect the final performance of water electrolysis and electrocatalytic coupling hydrogen production. Different main chains and catalysts have different modes of action. The anion exchange membrane prepared with terphenyl as the main chain has the best matching degree with the ionomer and catalyst.

[0204] The data from Examples 1, 5, and 6, and Comparative Examples 6, 7, 12, 13, 14, and 15 show that the number-average molecular weight and type of the ionomer and the membrane are mismatched. Since the ionomer acts as a binder and ion transfer agent, while a higher molecular weight increases its binding properties, the low solubility due to its large size affects its dispersibility, thus reducing the ion transfer performance at the ionomer-catalyst interface. Different number-average molecular weights of anion exchange membranes directly affect ion conductivity. A suitable number-average molecular weight is beneficial for improving the performance of the ionomer and anion exchange membrane in water electrolysis and coupled water electrolysis for hydrogen production.

[0205] The data from Examples 1, 7, 8, and 9, and Comparative Examples 1, 8, 9, 10, and 11 above show that the type of catalyst and its ratio to the ionomer respectively affect the performance of the water electrolysis and electrocatalytic coupling hydrogen production devices. The catalyst prepared in this patent exhibits excellent electrochemical characteristics when applied in water electrolysis and electrocatalytic coupling hydrogen production systems.

[0206] The data from Examples 1, 10, 11 and Comparative Examples 16, 17 show that the thickness of the anion exchange membrane affects the performance of hydrogen production through water electrolysis and coupled water electrolysis. Increasing the membrane thickness leads to a decrease in ionic conductivity, which in turn increases the internal resistance of the device. A suitable membrane thickness is beneficial to the performance of the anion exchange membrane in both water electrolysis and coupled water electrolysis hydrogen production.

[0207] The data from Example 1 and Comparative Examples 2 and 3 show that the degree of quaternization affects the performance of the ionomer and anion exchange membrane in hydrogen production via water electrolysis and coupled water electrolysis. The anion exchange polymer mainly relies on the quaternary ammonium groups in its molecules to transport hydroxide ions. Unquaternized polymers lack groups capable of transporting hydroxide ions, resulting in reduced performance. A higher degree of quaternization is beneficial for improving the performance of the ionomer and anion exchange membrane prepared from the anion exchange polymer in hydrogen production via water electrolysis and coupled water electrolysis.

[0208] As shown in Table 1, the membrane electrode assembly prepared in this invention can achieve 70 mA·cm⁻¹ at 1V in the methanol electrocatalytic coupling hydrogen production test. -2 The current density can reach 1250 mA·cm⁻¹ under 1.8V conditions in alkaline water electrolysis hydrogen production tests. -2 The current density indicates that the catalyst NiFeRu and the polyarylpiperidine ionomer have a synergistic effect. Using the same material to prepare the membrane and membrane electrode assembly significantly enhances the efficiency of methanol electrocatalytic oxidation coupled with alkaline water electrolysis for hydrogen production.

[0209] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A membrane electrode assembly, characterized by: The membrane electrode assembly comprises a polymer membrane and catalyst layers located or attached to both surfaces of the polymer membrane, and the catalyst layers comprise ionomers and catalysts; The polymer and ionomer in the polymer membrane each comprise or are any one or more of the following polyarylpiperidine polymers of the general formula: R is any one or more of the four groups on the right, wherein * represents a connection site.

2. The membrane electrode assembly according to claim 1, wherein: The polyarylpiperidine polymer used in the ionomer has a number average molecular weight of 5000-10000 and a polymer molecular weight dispersity index of 1-3; The polyarylpiperidine polymer used in the polymer membrane has a number average molecular weight of 10000-80000, a polymer molecular weight dispersity index of 1-3, and a thickness of 20-90 microns of a dense membrane; Preferably, R is the same in the molecular structure of the polymer or ionomer.

3. The membrane electrode assembly according to claim 1, wherein: A gas diffusion layer is provided on the surface of one or both of the catalyst layers away from the polymer membrane; The catalyst in the catalyst layer is an inorganic catalyst.

4. The membrane-electrode assembly as claimed in claim 3, characterized in that: The catalyst is NiFeRu; wherein the molar ratio of Ni / Fe is 5:1-1:1, and the molar ratio of Fe / Ru is 4:1-2:1; the catalyst is a layer with a surface area of 2000-10000 square nanometers and a thickness of 5-20 nanometers.

5. The membrane electrode assembly according to any one of claims 1-4, wherein: The polyarylpiperidine polymer is obtained by condensation polymerization of piperidone and aromatic monomers under the catalysis of trifluoroacetic acid and trifluoromethanesulfonic acid to obtain a non-quaternized polymer; the polymerization temperature is 0-5℃, and polymers with different molecular weights are obtained by controlling the reaction time; The piperidine functional group of the polymer is then modified by an iodomethane quaternization reaction to obtain the polyarylpiperidine polymer with quaternized piperidinium groups; The piperidone is 1-methyl-4-piperidone; The aromatic monomer is any one or more of terphenyl, bi-phenyl, 2,7-dimethylfluorene, or 1,2-diphenylethane.

6. The membrane electrode assembly according to claim 1 or 2, wherein: The polymer membrane is prepared as follows: 1) A polymer organic solution is prepared by casting a polyarylpiperidine polymer organic solution on a flat plate using a casting method; The polymer organic solution is prepared by dissolving a polyarylpiperidine polymer in an organic solvent; The concentration thereof in the organic solution is 0.05-0.2 g·mL -1 The organic solvent includes one or two or more of DMSO, DMC, NMP, DMF. 2) After casting, the organic solvent is dried and volatilized at a temperature of 50-80℃ for 24-48 hours; 3) After drying, the flat plate with the polymer membrane is removed and soaked in water for 3-5 hours to remove the membrane; 4) The removed membrane is soaked in a 1-3M KCl and / or NaCl solution, and the temperature is maintained at 50-80℃, and the membrane is soaked for a total of 4-7 times, each time for 6-12 hours; then the membrane is soaked in a 1-3M KHCO3 and / or NaHCO3 solution, and the temperature is maintained at 50-80℃, and the membrane is soaked for a total of 4-7 times, each time for 6-12 hours; finally, the membrane is washed with water for 2-3 times and naturally air-dried at room temperature to obtain the polymer membrane.

7. A method for preparing the membrane electrode assembly according to any one of claims 1 to 6, comprising the following steps: 1) soaking the polyaryl-piperidine high polymer in 1-3 M KCl and / or NaCl solution at a temperature of 50-80°C for 4-7 times, each time for 6-12 hours, then soaking in 1-3 M KHCO3 and / or NaHCO3 solution at a temperature of 50-80°C for 4-7 times, each time for 6-12 hours, and finally washing with water for 2-3 times and air-drying at room temperature to obtain the ionomer; 2) dissolving the ionomer in an organic solvent to obtain an ionomer solution; the mass fraction of the polymer is 1-10%; the organic solvent comprises one or more than two of ethanol, isopropanol and dimethyl sulfoxide; mixing the catalyst and water to prepare a catalyst dispersion liquid; the concentration of the catalyst (calculated by the mass ratio of the catalyst to water) is 2%-5%; mixing the ionomer solution and the catalyst dispersion liquid to obtain a catalyst-ionomer dispersion liquid; the proportion of the ionomer solution to the catalyst dispersion liquid (calculated by the mass ratio of the ionomer to the catalyst) is 5%-20%; the mixing temperature is 30-50°C; the thickness of the foamed nickel is 0.2-1 mm, and the porosity is 50-98%; the thickness of the carbon paper is 0.2-1 mm, and the porosity is 50-98%; 3) The prepared catalyst ionomer dispersion liquid is respectively brushed on the surface of the gas diffusion layer of the anode and the cathode to prepare the gas diffusion electrode, wherein the anode uses foamed nickel as the gas diffusion layer, and the cathode uses carbon paper as the gas diffusion layer, wherein the catalyst loading is 1-5 mg·cm -2 , the brushing temperature is kept at 50-70 DEG C, the brushing times are respectively 8-15 times, and the brushing ensures the uniform loading of the catalyst; the gas diffusion electrode of the anode and the cathode is obtained; 4) stacking the cathode gas diffusion electrode, the anion exchange membrane and the anode gas diffusion electrode, so that the catalyst-ionomer dispersion liquid brushing side of the cathode gas diffusion electrode and the anode gas diffusion electrode faces the anion exchange membrane, and pressing at room temperature or hot pressing on both sides of the anion exchange membrane to obtain the membrane electrode assembly; the pressure of the room temperature pressing is 0.1-5 MPa, and the time of the room temperature pressing is 0.5 min-30 min; the pressure of the hot pressing is 0.1-5 MPa, the temperature of the hot pressing is 60°C-100°C, and the time of the hot pressing is 10 s-1 min. The membrane electrode assembly is an anion exchange membrane membrane electrode assembly, which can be used as a membrane electrode for the process of methanol electrocatalytic oxidation coupling hydrogen production or alkaline water electrolysis hydrogen production.

8. Use of the anion exchange membrane-membrane electrode assembly according to any one of claims 1 to 6, characterized in that ​

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