阅读说明：本技术 一种超薄复合阴离子交换膜的制备方法 (Preparation method of ultrathin composite anion exchange membrane ) 是由 魏子栋 王建川 陈四国 李莉 袁伟 于 2021-04-23 设计创作，主要内容包括：本发明提供一种超薄复合阴离子交换膜制备方法,属于燃料电池技术领域；本发明通过无溶剂原位聚合的方法在多孔薄膜孔道里实现聚电解质填充,一方面,无溶剂引入可以保证多孔膜填充致密；另一方面,利用聚电解质单体原位自交联聚合可以保证聚电解质不发生泄露现象；通过改善制备工艺的和调控交联剂摩尔比例,可以使超薄复合阴离子交换膜与基底膜几乎保持相同薄的厚度(4μm),复合膜的机械强度超过150MPa,并获得超过1W/cm～(2)的较高燃料电池功率密度；本发明方法简单易行,生产成本低廉,采用本发明制备的阴离子交换膜可以应用于碱性燃料电池；用本发明制造的碱性燃料电池,可以应用于燃料电池动力汽车,各种航天器,便携式能源设备等。(The invention provides a preparation method of an ultrathin composite anion exchange membrane, belonging to the technical field of fuel cells; according to the invention, polyelectrolyte filling is realized in porous membrane pore channels by a solvent-free in-situ polymerization method, on one hand, the introduction of no solvent can ensure that the porous membrane is densely filled; on the other hand, the in-situ self-crosslinking polymerization of the polyelectrolyte monomer can ensure the polyelectrolyteThe leakage phenomenon does not occur; by improving the preparation process and regulating the molar ratio of the cross-linking agent, the ultrathin composite anion exchange membrane and the base membrane can be kept to be almost the same thickness (4 mu m), the mechanical strength of the composite membrane exceeds 150MPa, and the thickness exceeds 1W/cm 2 Higher fuel cell power density; the method is simple and easy to implement, the production cost is low, and the anion exchange membrane prepared by the method can be applied to alkaline fuel cells; the alkaline fuel cell manufactured by the invention can be applied to fuel cell powered vehicles, various spacecrafts, portable energy equipment and the like.)

1. Preparation method of ultrathin composite anion exchange membrane

(1) Treatment of polymer porous film

Cutting a commercially available polymer porous film into a proper area, soaking the commercially available polymer porous film in a methanol solution for 1 hour at room temperature, washing the commercially available polymer porous film for 3 times by using methanol to remove residual impurities of the porous film, drying the porous film for 4 hours at 50 ℃ under a vacuum condition, and cooling the porous film to room temperature for later use;

(2) and initiator treatment

Using chloroform as a solvent, preparing a dibenzoyl peroxide (BPO) solution with the mass percentage concentration of 30 wt%, then dropwise adding the BPO solution into a methanol solution, cooling to 0 ℃ for recrystallization, then filtering, washing for 3 times by using the methanol solution with the temperature of 0 ℃, and carrying out vacuum drying on a filtered product at the temperature of 30 ℃ for 12 hours to obtain a purified BPO initiator;

(3) preparation of ultrathin composite film

Firstly, respectively enabling chloromethyl styrene (VBC) and Divinylbenzene (DVB) to pass through a chromatographic column by using commercially available alkaline alumina (200-300 meshes), and removing a polymerization inhibitor in a monomer to obtain purified VBC and DVB; subsequently, the mixture is mixed according to a molar ratio of 1: 0.075-0.2: 0.008-0.04, respectively weighing the purified VBC, DVB and BPO, adding the weighed VBC and DVB into a single-neck flask, stirring for 5-20 min at 10-30 ℃, adding the weighed BPO, continuously stirring for 10-30 min at 10-30 ℃, and stopping stirring to obtain a reactant solution; spreading the polymer porous film treated in the step (1) on a glass plate, placing the glass plate on a vacuum container, and dropwise adding a reactant solution on the polymer porous film at normal temperature, wherein the loading capacity of the solution on the surface of the film is 0.01-0.04 g/cm²After the reactant solution is completely soaked, placing a glass plate on the upper surface of the porous film to form a sandwich structure, then filling nitrogen into a vacuum container and removing air, standing for 30-60 min, heating to 60-80 ℃ and keeping for 12-48 h, cooling to room temperature, taking out, washing with methanol for 3 times at normal temperature, and placing in a vacuum environment at 40-60 ℃ for drying for 12h to obtain an ultrathin composite film;

(4) preparation of quaternized ultrathin composite film

And (3) soaking the ultrathin composite membrane prepared in the step (3) in a tetrahydrofuran solution with the mass percentage of N-methylpiperidine of 20 wt% for 2 days at 40 ℃, then washing with deionized water for 3 times, soaking in a KOH solution with the mol/L at 40 ℃ for 1 day, then washing with deionized water for 3 times, and carrying out vacuum drying at 40-60 ℃ for 24 hours to obtain the quaternized ultrathin composite membrane.

2. The method of claim 1, wherein the porous polymer membrane is one of an ultra-high molecular weight polyethylene (UHMWPE, thickness of 3-10 μm) or a polytetrafluoroethylene (PTFE, thickness of 5-10 μm).

3. The preparation method of the ultrathin composite anion-exchange membrane according to claim 1, characterized by comprising the specific preparation method of step (3):

(3) preparation of ultrathin composite film

Firstly, respectively enabling chloromethyl styrene (VBC) and Divinylbenzene (DVB) to pass through a chromatographic column by using commercially available alkaline alumina (200-300 meshes), and removing a polymerization inhibitor in a monomer to obtain purified VBC and DVB; subsequently, the mixture is mixed according to a molar ratio of 1: 0.1: 0.02, respectively weighing the purified VBC, DVB and BPO, firstly adding the weighed VBC and DVB into a single-neck flask, stirring for 10min at the temperature of 20 ℃, then adding the weighed BPO, continuously stirring for 20min at the temperature of 20 ℃, and stopping stirring to obtain a reactant solution; spreading the UHMWPE porous film treated in the step (1) on a glass plate, placing the glass plate on a vacuum container, dropwise adding a reactant solution on the polymer porous film at normal temperature, wherein the loading capacity of the solution on the surface of the film is 0.02g/cm²After the reactant solution is completely soaked, placing a glass plate on the upper surface of the porous film to form a sandwich structure, then filling nitrogen into a vacuum container and removing air, standing for 60min, heating to 80 ℃ and keeping for 12h, cooling to room temperature, taking out, washing for 3 times by using methanol at normal temperature, and placing in a vacuum environment at 40 ℃ for drying for 12h to obtain the ultrathin composite film.

4. The preparation method of the ultrathin composite anion-exchange membrane according to claim 1, characterized by comprising the specific preparation method of step (3):

(3) preparation of ultrathin composite film

Firstly, respectively enabling chloromethyl styrene (VBC) and Divinylbenzene (DVB) to pass through a chromatographic column by using commercially available alkaline alumina (200-300 meshes), and removing a polymerization inhibitor in a monomer to obtain purified VBC and DVB; then, according to the moleThe molar ratio is 1: 0.075: 0.03, respectively weighing the purified VBC, DVB and BPO, firstly adding the weighed VBC and DVB into a single-neck flask, stirring for 15min at 25 ℃, then adding the weighed BPO, continuously stirring for 10min at 25 ℃, and stopping stirring to obtain a reactant solution; spreading the UHMWPE porous film treated in the step (1) on a glass plate, placing the glass plate on a vacuum container, dropwise adding a reactant solution on the macromolecular porous film at normal temperature, wherein the loading capacity of the solution on the surface of the film is 0.03g/cm²After the reactant solution is completely soaked, placing a glass plate on the upper surface of the porous film to form a sandwich structure, then filling nitrogen into a vacuum container and removing air, standing for 60min, heating to 70 ℃ and keeping for 12h, cooling to room temperature, taking out, washing with methanol for 3 times at normal temperature, and placing in a vacuum environment at 50 ℃ for drying for 12h to obtain the ultrathin composite film.

5. The preparation method of the ultrathin composite anion-exchange membrane according to claim 1, characterized by comprising the specific preparation method of step (3):

firstly, respectively enabling chloromethyl styrene (VBC) and Divinylbenzene (DVB) to pass through a chromatographic column by using commercially available alkaline alumina (200-300 meshes), and removing a polymerization inhibitor in a monomer to obtain purified VBC and DVB; subsequently, the mixture is mixed according to a molar ratio of 1: -0.15: 0.04, respectively weighing the purified VBC, DVB and BPO, firstly adding the weighed VBC and DVB into a single-neck flask, stirring for 10min at 15 ℃, then adding the weighed BPO, continuously stirring for 15min at 15 ℃, and stopping stirring to obtain a reactant solution; spreading the UHMWPE porous film treated in the step (1) on a glass plate, placing the glass plate on a vacuum container, dropwise adding a reactant solution on the macromolecular porous film at normal temperature, wherein the loading capacity of the solution on the surface of the film is 0.01g/cm²Placing a glass plate on the upper surface of the porous film after the reactant solution is completely soaked to form a sandwich structure, then filling nitrogen into a vacuum container and removing air, standing for 40min, heating to 60 ℃ and keeping for 24h, cooling to room temperature, taking out, washing with methanol at room temperature for 3 times, standing, and dryingDrying for 12h in a vacuum environment at 40 ℃ to obtain the ultrathin composite membrane.

The technical field is as follows:

the invention belongs to the technical field of fuel cells, and particularly relates to a preparation method of an ultrathin composite anion exchange membrane.

Secondly, background art:

environmental problems brought by traditional fossil energy compel human to pursue more efficient and clean energy approaches, China proposes that the aim of carbon neutralization is achieved in 2060, and a fuel cell is one of important approaches for solving the problems due to the advantages of high energy conversion efficiency and no pollution. The proton exchange membrane fuel cell popularized by the current policy is high in cost due to excessive dependence on a noble metal catalyst, and the large-scale application of the proton exchange membrane fuel cell is disturbed. Compared with proton exchange membrane fuel cells, alkaline anion exchange membrane fuel cells can use non-noble metals as catalysts instead of noble metal platinum, and are considered to be a more potential fuel cell type. As a core component of the alkaline anion exchange membrane fuel cell, a high-performance anion exchange membrane with high conductivity, good mechanical stability and chemical stability has been a core obstacle to commercialization of the alkaline fuel cell. In order to reduce the ohmic internal resistance of the fuel cell and obtain higher power output, the anion exchange membrane should be as thin as possible on the basis of ensuring the basic performance. However, in the ultra-thin state where the thickness of the homogeneous anion exchange membrane is reduced to 10 μm or less, the risk of gas fuel permeation and the mechanical stability are at great risk. Therefore, the anion exchange membrane is prepared by ultrathin compounding, so that the performance of the alkaline fuel cell is improved, and the method has important significance.

Although a great deal of research is carried out on the preparation of the composite anion exchange membrane at home and abroad up to now, the composite anion exchange membrane can be really ultra-thin (<10 μm) layer was hardly studied. Chinese patent 'ultra-thin cross-linked composite reinforced polymer anion exchange membrane and preparation method and application thereof' (patent application number: 201811436085.2) discloses a method for preparing a multi-component ion exchange membrane by using low-cost ultra-thin polymerThe thickness of the cross-linked composite membrane prepared by thermal initiation polymerization in the pore canal is reduced to 10 mu m, and the cross-linked composite membrane has higher mechanical strength, dimensional stability and electric conductivity, but the power density of the fuel cell based on the membrane is only 379mW/cm². The existing research shows that the composite anion-exchange membrane compounded by the matrix porous membrane generally has higher mechanical stability and shows great application prospect. However, an ultra-thin composite anion exchange membrane having a thickness of less than 10 μm and satisfying the requirements for fuel cell applications in terms of gas barrier properties and mechanical stability has not been reported yet.

Thirdly, the invention content:

the invention aims to provide a preparation method of an ultrathin composite anion exchange membrane aiming at the defects of higher thickness (meaning large ohmic internal resistance of a battery membrane), large risk of gas permeability, low performance of a fuel battery and the like of the existing anion exchange membrane. On the basis of surface treatment of the polymer porous film and blending of a reaction mixture, polyelectrolyte monomer in-situ polymerization and crosslinking are realized in the pore canal of the polymer porous film by a solvent-free in-situ polymerization method, and on one hand, the solvent-free method can ensure that the porous film is compactly filled; on the other hand, the polyelectrolyte in-situ polymerization crosslinking can ensure that the polyelectrolyte does not run off. More importantly, the thickness of the composite membrane can be controlled below 10 mu m by combining the improvement of the preparation process and the control of the crosslinking degree, and the composite membrane has ultrahigh mechanical strength, lower hydrogen permeability and excellent fuel cell performance.

The purpose of the invention is realized as follows: a preparation method of an ultrathin composite anion exchange membrane comprises the following specific steps:

(1) treatment of polymer porous film

Cutting a commercially available polymer porous film into a proper area, soaking the commercially available polymer porous film in a methanol solution for 1 hour at room temperature, washing the commercially available polymer porous film for 3 times by using methanol to remove residual impurities of the porous film, drying the porous film for 4 hours at 50 ℃ under a vacuum condition, and cooling the porous film to room temperature for later use;

(2) and initiator treatment

Using chloroform as a solvent, preparing a dibenzoyl peroxide (BPO) solution with the mass percentage concentration of 30 wt%, then dropwise adding the BPO solution into a methanol solution, cooling to 0 ℃ for recrystallization, then filtering, washing for 3 times by using the methanol solution with the temperature of 0 ℃, and carrying out vacuum drying on a filtered product at the temperature of 30 ℃ for 12 hours to obtain a purified BPO initiator;

(3) preparation of ultrathin composite film

Firstly, respectively enabling chloromethyl styrene (VBC) and Divinylbenzene (DVB) to pass through a chromatographic column by using commercially available alkaline alumina (200-300 meshes), and removing a polymerization inhibitor in a monomer to obtain purified VBC and DVB; subsequently, the mixture is mixed according to a molar ratio of 1: 0.075-0.2: 0.008-0.04, respectively weighing the purified VBC, DVB and BPO, adding the weighed VBC and DVB into a single-neck flask, stirring for 5-20 min at 10-30 ℃, adding the weighed BPO, continuously stirring for 10-30 min at 10-30 ℃, and stopping stirring to obtain a reactant solution; spreading the polymer porous film treated in the step (1) on a glass plate, placing the glass plate on a vacuum container, and dropwise adding a reactant solution on the polymer porous film at normal temperature, wherein the loading capacity of the solution on the surface of the film is 0.01-0.04 g/cm²After the reactant solution is completely soaked, placing a glass plate on the upper surface of the porous film to form a sandwich structure, then filling nitrogen into a vacuum container and removing air, standing for 30-60 min, heating to 60-80 ℃ and keeping for 12-48 h, cooling to room temperature, taking out, washing with methanol for 3 times at normal temperature, and placing in a vacuum environment at 40-60 ℃ for drying for 12h to obtain an ultrathin composite film;

(4) preparation of quaternized ultrathin composite film

Soaking the ultrathin composite membrane prepared in the step (3) in a tetrahydrofuran solution with the mass percentage of N-methylpiperidine being 20 wt% for 2 days at 40 ℃, then washing the membrane for 3 times by using deionized water, soaking the membrane in a KOH solution with the mol/L for 1 day at 40 ℃, then washing the membrane for 3 times by using the deionized water, and carrying out vacuum drying for 24 hours at 40-60 ℃ to obtain a quaternized ultrathin composite membrane;

wherein the high molecular porous film is one of an ultrahigh molecular weight polyethylene film (UHMWPE, the thickness of which is 3-10 μm) or a polytetrafluoroethylene film (PTFE, the thickness of which is 5-10 μm).

After the technical scheme is adopted, the invention mainly has the following advantages:

(1) the filling of the ultrathin composite membrane is very compact, and unfilled pore channels do not appear. H₂The gas permeability is low, the open circuit voltage of the fuel cell operation can be effectively ensured, and the gas fuel permeation is effectively prevented.

(2) The ultrathin composite membrane has mechanical strength of more than 150MPa and low water absorption and swelling property, is very beneficial to the preparation of a membrane electrode, and ensures the mechanical stability of the membrane of the fuel cell in a complex environment.

(3) The thickness of the ultrathin composite membrane is less than 10 mu m, the ultrathin membrane is realized, the ohmic resistance of the fuel cell membrane is effectively reduced, and the thickness of the ultrathin composite membrane is more than 1W cm^-2Peak fuel cell power.

The method is simple and efficient, the production cost is low, and the ultrathin composite anion exchange membrane prepared by the method can be applied to alkaline fuel cells. The alkaline fuel cell manufactured by the invention is widely applied to electric automobiles, various spacecrafts, portable mobile power supplies and the like. (availability)

Fourthly, explanation of the attached drawings:

fig. 1 is an SEM image of a UHMWPE porous membrane, an ultrathin composite anion exchange membrane prepared in example 1: fig. a, b are plan and cross-sectional SEM images of the UHMWPE porous membrane, and c, d are plan and cross-sectional SEM images of the composite membrane of example 1.

Fig. 2 is a mechanical property diagram of the UHMWPE porous membrane, the ultrathin composite anion exchange membrane prepared in example 1, and the Nafion HP membrane: the line of curve 1 represents the UHMWPE porous film (dry), the line of curve 2 represents the UHMWPE porous film (wet), the line of curve 3 represents the composite membrane prepared in example 1 (dry), the line of curve 4 represents the composite membrane prepared in example 1 (wet), the line of curve 5 represents the Nafion HP membrane (dry), and the line of curve 6 represents the Nafion HP membrane (wet).

FIG. 3 is a graph showing hydrogen permeability test of the ultra-thin composite membrane prepared in example 1 and a Nafion HP membrane.

FIG. 4 is a schematic representation of the ultra-thin composite anion exchange membrane prepared and the commercially available anion of the comparative experimental examplesProton exchange membraneH of W-25 film₂/O₂Alkaline fuel cell performance map: curve 1 corresponds to the power density curve of the composite film of example 1, curve 2 corresponds to the power density curve of the composite film of example 2, curve 3 corresponds to the power density curve of the composite film of example 3, and curve 4 corresponds to the power density curve of the composite film of comparative examplePower density curve of W-25 film. The operating conditions are as follows: the temperature of the cell is 65 ℃, pure hydrogen is used as fuel, pure oxygen is used as oxidant, the back pressure of the anode and the cathode is 150KPa, and the air flow of the anode and the cathode is 0.5 liter/minute.

The fifth embodiment is as follows:

the present invention will be further described with reference to the following specific embodiments.

Example 1

(1) Treatment of polymer porous film

Cutting a commercially available UHMWPE porous film into an area with a proper size, soaking the commercially available UHMWPE porous film in a methanol solution for 1 hour at room temperature, washing the commercially available UHMWPE porous film for 3 times by using methanol to remove residual impurities of the porous film, drying the porous film for 4 hours at 50 ℃ under a vacuum condition, and cooling the porous film to room temperature for later use;

(2) and initiator treatment

Using chloroform as a solvent, preparing a dibenzoyl peroxide (BPO) solution with the mass percentage concentration of 30 wt%, then dropwise adding the BPO solution into a methanol solution, cooling to 0 ℃ for recrystallization, then filtering, washing for 3 times by using the methanol solution with the temperature of 0 ℃, and carrying out vacuum drying on a filtered product at the temperature of 30 ℃ for 12 hours to obtain a purified BPO initiator;

(3) preparation of ultrathin composite film

Firstly, respectively enabling chloromethyl styrene (VBC) and Divinylbenzene (DVB) to pass through a chromatographic column by using commercially available alkaline alumina (200-300 meshes), and removing a polymerization inhibitor in a monomer to obtain purified VBC and DVB; subsequently, the mixture is mixed according to a molar ratio of 1: 0.1: 0.02, respectively weighing and purifyingAdding weighed VBC and DVB into a single-neck flask, stirring for 10min at 20 ℃, adding weighed BPO, continuously stirring for 20min at 20 ℃, and stopping stirring to obtain a reactant solution; spreading the UHMWPE porous film treated in the step (1) on a glass plate, placing the glass plate on a vacuum container, dropwise adding a reactant solution on the polymer porous film at normal temperature, wherein the loading capacity of the solution on the surface of the film is 0.02g/cm²After the reactant solution is completely soaked, placing a glass plate on the upper surface of the porous film to form a sandwich structure, then filling nitrogen into a vacuum container and removing air, standing for 60min, heating to 80 ℃ and keeping for 12h, cooling to room temperature, taking out, washing for 3 times by using methanol at normal temperature, and placing in a vacuum environment at 40 ℃ for drying for 12h to obtain the ultrathin composite film;

(4) preparation of quaternized ultrathin composite film

Soaking the ultrathin composite membrane prepared in the step (3) in a tetrahydrofuran solution with the mass percentage of N-methylpiperidine being 20 wt% for 2 days at 40 ℃, then washing the membrane for 3 times by using deionized water, soaking the membrane in a KOH solution with the mol/L for 1 day at 40 ℃, then washing the membrane for 3 times by using the deionized water, and carrying out vacuum drying for 24 hours at 40-60 ℃ to obtain a quaternized ultrathin composite membrane;

(5) performance test of ultrathin composite film

Characterization of the morphology of the ultrathin composite film: respectively cutting 1cm multiplied by 3cm of ultrathin composite anion exchange membrane sample and UHMWPE porous film sample, placing in liquid nitrogen for 30min, brittle fracture, spraying gold for 20s by a vacuum coating instrument, and observing the section and surface of the sample by a Nova Nano SEM 450 model Scanning Electron Microscope (SEM) instrument under the voltage of 5kV, wherein the result is shown in figure 1;

and (3) testing the mechanical properties of the ultrathin composite film: respectively cutting two ultrathin composite anion exchange membrane samples of 1cm multiplied by 3cm and UHMWPE porous film samples; one is placed in deionized water for 24 hours and then is tested after surface moisture is quickly wiped, and the other is tested after vacuum drying at 40 ℃ for 24 hours; the test is carried out by adopting an MTS tensile tester (E44.104) model universal material tester under the conditions of 25 ℃ and 5mm/min of tensile rate, and a curve shown in figure 2 is obtained;

testing the hydrogen permeability of the ultrathin composite membrane: cutting 5cm × 5cm of ultrathin composite anion exchange membrane and Nafion HP membrane, performing 150kPa back pressure at 60 deg.C, testing with hydrogen gas and relative humidity of 0% RH and 100% RH, and detecting with Agilent 7890B gas chromatograph to obtain test results shown in FIG. 3;

(6) fuel cell performance test

First, 0.75g of a commercially available 60 wt% Pt/C and PtRu/C catalyst, respectively, was weighed into a plastic sample tube, followed by 0.8mL of isopropanol solution, after which 37.5. mu.L of a commercially available solution was added to the sample tubeIonomer (5 wt% DMSO solution), and performing ultrasonic treatment on the sample tube in a water bath for 1h to form catalyst ink for later use; taking out the ultrathin composite anion exchange membrane of 5cm multiplied by 5cm prepared in the step (4), respectively spraying 60 wt% of Pt/C and PtRu/C catalyst ink prepared by ultrasonic on two sides of the membrane to form a cathode catalyst layer and an anode catalyst layer, wherein the catalyst loading amounts are 0.4mg/cm²The prepared structure is a fuel Cell Chip (CCM); finally, the prepared CCM was sandwiched between two 2.5cm × 2.5cm pieces of commercially available carbon paper to form a sandwich structure, which was placed in a fuel cell test fixture, and a cell performance test was performed using a fuel cell test system (850e Multi Range, Scribner Associates Co). The test conditions were: the temperature of the cell is 65 ℃, pure hydrogen is used as fuel, pure oxygen is used as oxidant, the back pressure of the anode and the cathode is 150KPa, and the air flow of the anode and the cathode is 0.5 liter/minute. The cell power test was performed and the test results are shown in the graph of example 1 of fig. 4.

Example 2

(1) Treatment of polymer porous film

Cutting a commercially available UHMWPE porous film into an area with a proper size, soaking the commercially available UHMWPE porous film in a methanol solution for 1 hour at room temperature, washing the commercially available UHMWPE porous film for 3 times by using methanol to remove residual impurities of the porous film, drying the porous film for 4 hours at 50 ℃ under a vacuum condition, and cooling the porous film to room temperature for later use;

(2) and initiator treatment

Using chloroform as a solvent, preparing a dibenzoyl peroxide (BPO) solution with the mass percentage concentration of 30 wt%, then dropwise adding the BPO solution into a methanol solution, cooling to 0 ℃ for recrystallization, then filtering, washing for 3 times by using the methanol solution with the temperature of 0 ℃, and carrying out vacuum drying on a filtered product at the temperature of 30 ℃ for 12 hours to obtain a purified BPO initiator;

(3) preparation of ultrathin composite film

Firstly, respectively enabling chloromethyl styrene (VBC) and Divinylbenzene (DVB) to pass through a chromatographic column by using commercially available alkaline alumina (200-300 meshes), and removing a polymerization inhibitor in a monomer to obtain purified VBC and DVB; subsequently, the mixture is mixed according to a molar ratio of 1: 0.075: 0.03, respectively weighing the purified VBC, DVB and BPO, firstly adding the weighed VBC and DVB into a single-neck flask, stirring for 15min at 25 ℃, then adding the weighed BPO, continuously stirring for 10min at 25 ℃, and stopping stirring to obtain a reactant solution; spreading the UHMWPE porous film treated in the step (1) on a glass plate, placing the glass plate on a vacuum container, dropwise adding a reactant solution on the macromolecular porous film at normal temperature, wherein the loading capacity of the solution on the surface of the film is 0.03g/cm²After the reactant solution is completely soaked, placing a glass plate on the upper surface of the porous film to form a sandwich structure, then filling nitrogen into a vacuum container and removing air, standing for 60min, heating to 70 ℃ and keeping for 12h, cooling to room temperature, taking out, washing for 3 times by using methanol at normal temperature, and placing in a vacuum environment at 50 ℃ for drying for 12h to obtain the ultrathin composite film;

(4) preparation of quaternized ultrathin composite film

Soaking the ultrathin composite membrane prepared in the step (3) in a tetrahydrofuran solution with the mass percentage of N-methylpiperidine being 20 wt% for 2 days at 40 ℃, then washing the membrane for 3 times by using deionized water, soaking the membrane in a KOH solution with the mol/L for 1 day at 40 ℃, then washing the membrane for 3 times by using the deionized water, and carrying out vacuum drying for 24 hours at 40-60 ℃ to obtain a quaternized ultrathin composite membrane;

(5) fuel cell performance test

First, 0.75g of a commercially available 60 wt% Pt/C and PtRu/C catalyst, respectively, was weighed into a plastic sample tube, followed by 0.8mL of isopropanol solution, after which 37.5. mu.L of a commercially available solution was added to the sample tubeIonomer (5 wt% DMSO solution), and performing ultrasonic treatment on the sample tube in a water bath for 1h to form catalyst ink for later use; taking out the ultrathin composite anion exchange membrane of 5cm multiplied by 5cm prepared in the step (4), respectively spraying 60 wt% of Pt/C and PtRu/C catalyst ink prepared by ultrasonic on two sides of the membrane to form a cathode catalyst layer and an anode catalyst layer, wherein the catalyst loading amounts are 0.4mg/cm²The prepared structure is a fuel Cell Chip (CCM); finally, the prepared CCM was sandwiched between two 2.5cm × 2.5cm pieces of commercially available carbon paper to form a sandwich structure, which was placed in a fuel cell test fixture, and a cell performance test was performed using a fuel cell test system (850e Multi Range, Scribner Associates Co). The test conditions were: the temperature of the cell is 65 ℃, pure hydrogen is used as fuel, pure oxygen is used as oxidant, the back pressure of the anode and the cathode is 150KPa, and the air flow of the anode and the cathode is 0.5 liter/minute. The cell power test was performed and the test results are shown in the graph of example 2 of fig. 4.

Example 3

(1) Treatment of high-molecular porous films

Cutting a commercially available UHMWPE porous film into an area with a proper size, soaking the commercially available UHMWPE porous film in a methanol solution for 1 hour at room temperature, washing the commercially available UHMWPE porous film for 3 times by using methanol to remove residual impurities of the porous film, drying the porous film for 4 hours at 50 ℃ under a vacuum condition, and cooling the porous film to room temperature for later use;

(2) and initiator treatment

Using chloroform as a solvent, preparing a dibenzoyl peroxide (BPO) solution with the mass percentage concentration of 30 wt%, then dropwise adding the BPO solution into a methanol solution, cooling to 0 ℃ for recrystallization, then filtering, washing for 3 times by using the methanol solution with the temperature of 0 ℃, and carrying out vacuum drying on a filtered product at the temperature of 30 ℃ for 12 hours to obtain a purified BPO initiator;

(3) preparation of ultrathin composite film

Firstly, respectively enabling chloromethyl styrene (VBC) and Divinylbenzene (DVB) to pass through a chromatographic column by using commercially available alkaline alumina (200-300 meshes), and removing a polymerization inhibitor in a monomer to obtain purified VBC and DVB; subsequently, the mixture is mixed according to a molar ratio of 1: -0.15: 0.04, respectively weighing the purified VBC, DVB and BPO, firstly adding the weighed VBC and DVB into a single-neck flask, stirring for 10min at 15 ℃, then adding the weighed BPO, continuously stirring for 15min at 15 ℃, and stopping stirring to obtain a reactant solution; spreading the UHMWPE porous film treated in the step (1) on a glass plate, placing the glass plate on a vacuum container, dropwise adding a reactant solution on the macromolecular porous film at normal temperature, wherein the loading capacity of the solution on the surface of the film is 0.01g/cm²After the reactant solution is completely soaked, placing a glass plate on the upper surface of the porous film to form a sandwich structure, then filling nitrogen into a vacuum container and removing air, standing for 40min, heating to 60 ℃ and keeping for 24h, cooling to room temperature, taking out, washing with methanol for 3 times at normal temperature, and drying in a vacuum environment at 40 ℃ for 12h to obtain the ultrathin composite film;

(4) preparation of quaternized ultrathin composite film

Soaking the ultrathin composite membrane prepared in the step (3) in a tetrahydrofuran solution with the mass percentage of N-methylpiperidine being 20 wt% for 2 days at 40 ℃, then washing the membrane for 3 times by using deionized water, soaking the membrane in a KOH solution with the mol/L for 1 day at 40 ℃, then washing the membrane for 3 times by using the deionized water, and carrying out vacuum drying for 24 hours at 40-60 ℃ to obtain a quaternized ultrathin composite membrane;

(5) fuel cell performance test

First, 0.75g of a commercially available 60 wt% Pt/C and PtRu/C catalyst, respectively, was weighed into a plastic sample tube, followed by 0.8mL of isopropanol solution, after which 37.5. mu.L of a commercially available solution was added to the sample tubeIonomer (5 wt% DMSO solution), and performing ultrasonic treatment on the sample tube in a water bath for 1h to form catalyst ink for later use; taking out stepRespectively spraying 60 wt% of Pt/C and PtRu/C catalyst ink prepared by ultrasonic treatment on two surfaces of the membrane to form a cathode catalyst layer and an anode catalyst layer, wherein the catalyst loading amounts are 0.4mg/cm²The prepared structure is a fuel Cell Chip (CCM); finally, the prepared CCM was sandwiched between two 2.5cm × 2.5cm pieces of commercially available carbon paper to form a sandwich structure, which was placed in a fuel cell test fixture, and a cell performance test was performed using a fuel cell test system (850e Multi Range, Scribner Associates Co). The test conditions were: the temperature of the cell is 65 ℃, pure hydrogen is used as fuel, pure oxygen is used as oxidant, the back pressure of the anode and the cathode is 150KPa, and the air flow of the anode and the cathode is 0.5 liter/minute. The single cell power test was performed and the test results are shown in fig. 4, example 3 curve.

Comparative example

Using commercially availableThe W-25 membrane (thickness: 25 + -2 μm; ion exchange capacity: 2.50 + -0.05; ionic conductivity: 140 + -10 mS/cm @80 ℃ C.; tensile strength: 33 + -3 MPa) was used as a comparative experimental example for the performance test of the fuel cell; first, 5cm × 5cm pieces are cutRemoving the outer plastic protective film from the W-25 membrane, taking out the middle anion exchange membrane, soaking in 1M KOH solution at 60 ℃ for 12h, washing with deionized water for 3 times, and drying in a vacuum oven for 12h for later use; thereafter, 0.75g of commercially available 60 wt% Pt/C and PtRu/C catalysts were weighed into plastic sample tubes, respectively, followed by 0.8mL of an aqueous solution, after which 37.5. mu.L of a commercially available solution was added to the sample tubesIonomer (5 wt% DMSO solution), and performing ultrasonic treatment on the sample tube in a water bath for 1h to form catalyst ink for later use; taking out the driedA W-25 type anion exchange membrane is prepared by respectively spraying 60 wt% Pt/C and PtRu/C catalyst ink prepared by ultrasonic on two sides of the membrane to form a cathode catalyst layer and an anode catalyst layer, wherein the catalyst loading amounts are 0.4mg/cm²The prepared structure is a fuel Cell Chip (CCM); finally, the prepared CCM was sandwiched between two 2.5cm × 2.5cm pieces of commercially available carbon paper to form a sandwich structure, which was placed in a fuel cell test fixture, and a cell performance test was performed using a fuel cell test system (850e Multi Range, Scribner Associates Co). The test conditions were: the temperature of the cell is 65 ℃, pure hydrogen is used as fuel, pure oxygen is used as oxidant, the back pressure of the anode and the cathode is 150KPa, and the air flow of the anode and the cathode is 0.5 liter/minute. The single cell power test was performed and the test results are shown in fig. 4 versus the comparative plot.

Test results of the present invention:

as can be seen from FIG. 1, the thickness of the prepared composite film is 4 μm, thus realizing the purpose of ultra-thinness; as can be seen in FIG. 2, the prepared composite film, whether dry film or wet film, has mechanical strength over 150MPa, elongation at break in the range of 50% -70%, and extremely high mechanical stability; as can be seen from fig. 3, the prepared composite membrane has a lower hydrogen permeation rate than the commercial Nafion HP membrane, and is effective in preventing fuel permeation. As can be seen from FIG. 4, the prepared composite membrane achieves more than 1W cm in the operation process of the fuel cell at 65 DEG C^-2The power density of the fuel cell has good fuel cell performance.