阅读说明：本技术 一种质子交换膜及其制备方法和应用 (Proton exchange membrane and preparation method and application thereof ) 是由 汝春宇 韩令海 盛夏 金守一 潘兴龙 许德超 刘颖 丁磊 于 2021-08-25 设计创作，主要内容包括：本发明涉及一种质子交换膜及其制备方法和应用,所述质子交换膜包括聚芳醚酮衍生物和金属有机骨架化合物；所述聚芳醚酮衍生物的主链含有氟原子且侧链含有磺酸基；所述金属有机骨架化合物同时包括氨基和磺酸基。本发明所述质子交换膜具有较低的溶胀率和甲醇渗透率,较高的质子传导率、甲醇渗透氧化电流密度和极限功率密度,在直接甲醇燃料电池中有良好的应用。(The invention relates to a proton exchange membrane and a preparation method and application thereof, wherein the proton exchange membrane comprises polyaryletherketone derivatives and metal organic framework compounds; the main chain of the polyaryletherketone derivative contains fluorine atoms and the side chain contains sulfonic groups; the metal organic framework compound includes both an amino group and a sulfonic acid group. The proton exchange membrane has lower swelling rate and methanol permeability, higher proton conductivity, methanol permeation oxidation current density and limiting power density, and has good application in direct methanol fuel cells.)

1. A proton exchange membrane is characterized in that the proton exchange membrane comprises polyaryletherketone derivatives and metal organic framework compounds;

the main chain of the polyaryletherketone derivative contains fluorine atoms and the side chain contains sulfonic groups;

the metal organic framework compound includes both an amino group and a sulfonic acid group.

2. The proton exchange membrane according to claim 1, wherein the polyaryletherketone derivative has a structure represented by formula I;

wherein R is₁And R₂Each independently selected from C2-C10 alkylene;

preferably, the molecular weight of the polyaryletherketone derivative is 30000-50000 g/mol.

3. The proton exchange membrane according to claim 1 or 2, wherein the metal organic framework compound comprises amino-sulfonic acid modified MIL-101.

4. The proton exchange membrane according to any one of claims 1 to 3, wherein the mass percentage of the metal organic framework compound in the polyaryletherketone derivative is 0.5% to 5%.

5. A method for preparing a proton exchange membrane according to any one of claims 1 to 4, wherein the method comprises the following steps: and mixing the polyaryletherketone derivative and the metal organic framework compound, dissolving, coating the mixture on a substrate, drying, and stripping the substrate to obtain the proton exchange membrane.

6. The method of claim 5, wherein the polyaryletherketone derivative is prepared by the steps of: reacting a polymer shown as a formula II with sultone to obtain the polyaryletherketone derivative;

preferably, the temperature of the reaction is 40-90 ℃;

preferably, the reaction time is 12-24 h;

preferably, the preparation method of the polymer shown in the formula II comprises the following steps: performing demethylation reaction on the polymer shown in the formula III to obtain a polymer shown in a formula II;

preferably, the solvent for the demethylation reaction comprises chloroform and boron tribromide.

7. The method according to claim 6, wherein the method for preparing the polymer of formula III comprises the following steps: carrying out polycondensation reaction on monomers shown in formulas IV and V to obtain a polymer shown in a formula III;

preferably, the catalyst for the polycondensation reaction comprises potassium carbonate;

preferably, the solvent of the polycondensation reaction comprises dimethyl sulfoxide;

preferably, the water-carrying agent of the polycondensation reaction comprises toluene;

preferably, the temperature of the polycondensation reaction is 120-180 ℃;

preferably, the preparation method of the monomer shown in the formula IV comprises the following steps: will be provided with Reacting to obtain a monomer shown in a formula IV;

the X is a halogen atom;

preferably, the solvent of the reaction comprises a combination of chloroform and ferric chloride.

8. The method according to any one of claims 5 to 7, wherein the method for preparing the metal-organic framework compound comprises the steps of: reacting 2-amino-terephthalic acid with Cr (NO)₃)₃·9H₂Performing hydrothermal reaction on O to form aminated MIL-101, and performing sulfonation reaction on the aminated MIL-101 and alkyl sultone to obtain a metal organic framework compound containing amino and sulfonic acid groups;

preferably, the temperature of the hydrothermal reaction is 120-200 ℃;

preferably, the time of the hydrothermal reaction is 18-32 h;

preferably, the hydrothermal reaction is followed by operations of centrifugation, reflux and drying in sequence;

preferably, the temperature of the sulfonation reaction is 80-120 ℃;

preferably, the sulfonation reaction time is 18-32 h;

preferably, the sulfonation reaction is followed by operations of centrifugation, reflux, acidification and deacidification.

9. The method according to any one of claims 5 to 8, characterized by comprising the steps of:

(1) preparation of polyaryletherketone derivatives:

will be provided withReacting in chloroform and ferric chloride to obtain a monomer shown in a formula IV;

carrying out polycondensation reaction on the monomers shown in the formulas IV and V at the temperature of 120-180 ℃ to obtain a polymer shown in a formula III;

performing demethylation reaction on the polymer shown in the formula III in chloroform and boron tribromide to obtain a polymer shown in a formula II;

reacting the polymer shown in the formula II with sultone at 40-90 ℃ for 12-24h to obtain the polyaryletherketone derivative;

(2) preparation of metal organic framework compound: reacting 2-amino-terephthalic acid with Cr (NO)₃)₃·9H₂Performing hydrothermal reaction on O at the temperature of 120-200 ℃ for 18-32h, performing operations of centrifugation, reflux and drying to form aminated MIL-101, performing sulfonation on the aminated MIL-101 and alkyl sultone at the temperature of 80-120 ℃ for 18-32h, and performing operations of centrifugation, reflux, acidification and deacidification to obtain a metal organic framework compound containing amino and sulfonic groups;

(3) preparing a proton exchange membrane: mixing and dissolving a polyaryletherketone derivative and a metal organic framework compound, coating the mixture on a substrate, drying, and stripping the substrate to obtain a proton exchange membrane;

wherein the polymer of formula II, the polymer of formula III, the monomer of formulae IV and V and X are as defined in any one of claims 6 to 8.

10. A direct methanol fuel cell comprising the proton exchange membrane of any one of claims 1 to 4.

Technical Field

The invention relates to the technical field of batteries, in particular to a proton exchange membrane and a preparation method and application thereof.

Background

The methanol has high safety and wide sources, is convenient to store and transport, and can realize the quick filling of fuel. Meanwhile, the internal structure and the used materials of the direct methanol fuel cell are basically the same as those of the proton exchange membrane fuel cell, and the development difficulty and the cost are not high. Therefore, the direct methanol fuel cell is more suitable for use as a portable fuel cell than the hydrogen-oxygen fuel cell.

The perfluorinated sulfonic acid (PFSA) type proton exchange membrane used at present has poor blocking effect on methanol fuel and high fuel permeability, and cannot give full play to the performance advantages of direct methanol fuel cells. The sulfonated polyaryl ether (SPAEs) polyelectrolyte material has excellent thermal stability, mechanical property, excellent proton conductivity and lower methanol permeability, and meets the performance requirement of a proton exchange membrane material. In addition, the SPAEs have simple molecular structure, are easy to design and synthesize, have relatively low manufacturing cost, and are an ideal substitute material of the PFSA substrate proton exchange membrane. In view of its rigid molecular structure, the SPAEs materials require a higher degree of sulfonation to achieve the same level of proton conductivity as PFSA-type proton exchange membranes. However, SPAEs with high sulfonation degree have high water absorption and swelling rate under high temperature and high humidity conditions, poor dimensional stability, serious influence on the stability of the performance of the fuel cell and shortened service life. Therefore, how to ensure that the SPAEs polyelectrolyte material has high proton conductivity and good dimensional stability is the first problem of research in the field.

The inorganic nano modifier is introduced into the sulfonated polyarylether polyelectrolyte substrate by adopting a doping mode to prepare the organic-inorganic composite proton exchange membrane, so that the limitation of a single polymer material is broken through, and the performance of the proton exchange membrane material is further improved.

Metal-organic framework compounds (MOFs) are a typical three-dimensional inorganic nanomaterial. Because the internal porosity and the specific surface area are large, and the structure is controllable, the material is easy to carry out physical filling and chemical modification functionalization, and is an ideal inorganic nano modifier. The pore channels in the MOFs material can be used as a container of a proton transmission medium to lock ionic liquid, heteropoly acid and the like, so that the problem of loss of the transmission medium in water is effectively reduced. Xubronze et al in "Anovel route for preparation of high purity product conductive membrane materials with metal-organic frames, Chemical Communications, 2013, 49, 143-145" studies, inorganic nano MOFs material Fe-MIL-101-NH₂The proton transmission capacity of the SPPO matrix exchange membrane material at normal temperature reaches 0.1S cm by being compounded with a sulfonated polyphenylene oxide (SPPO) polyelectrolyte substrate by a doping/grafting method^-1。

The MOFs material can not only carry out chemical structure modification and conduction medium filling functionalization on the MOFs material, but also form a composite nano modifier with other inorganic materials. In the research of "Rational Design of S-UO-66 @ GO Hybrid Nanosheets for Proton Exchange Membranes with signalling Enhanced Transport Performance, ACS Applied Materials & Interfaces,2017, 9, 22597 22603", S-UO-66 @ composite inorganic nanofiller Enhanced SPEEK matrix Proton Exchange membrane is prepared by in situ synthesis method, S-UO-66 with dense sulfonate Proton conducting groups is densely distributed on two-dimensional GO sheets to form continuous Proton conducting channels in the composite membrane, which not only can effectively enhance Proton conductivity but also can hinder diffusion of methanol molecules in the membrane, thereby enhancing alcohol-blocking Performance of the composite membrane.

Although many researches on preparing proton exchange membranes with better alcohol resistance performance exist at present, the types of the proton exchange membranes are relatively few, and the development of a proton exchange membrane material with better alcohol resistance performance is particularly critical for improving the performance of a direct methanol fuel cell.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a proton exchange membrane, a preparation method and application thereof.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the present invention provides a proton exchange membrane comprising a polyaryletherketone derivative and a metal organic framework compound;

the main chain of the polyaryletherketone derivative contains fluorine atoms and the side chain contains sulfonic groups;

the metal organic framework compound includes both an amino group and a sulfonic acid group.

The proton exchange membrane has lower swelling rate and methanol permeability, higher proton conductivity, methanol permeation oxidation current density and limiting power density, and is characterized in that: on the first hand, the introduction of the metal organic framework compound of the invention leads the proton exchange membrane to form an ion cross-linking structure, and limits the molecular chain segment motion of the surrounding polyaryletherketone derivative, thereby reducing the water absorption swelling rate of the membrane material; in the second aspect, the metal organic framework compound has a large amount of sulfonic acid groups, and the proton conductivity of the membrane can be improved to a certain extent by adding the sulfonic acid groups as fillers into a proton exchange membrane; in a third aspect, the metal organic framework compound comprises an amino group and a sulfonic group, the main chain of the polyaryletherketone derivative contains fluorine atoms, the side chain of the polyaryletherketone derivative contains the sulfonic group, and acid and base ions between the two molecules form ion crosslinking on acting force, so that the dimensional stability and the alcohol resistance of the membrane are obviously improved.

Preferably, the polyaryletherketone derivative has a structure shown in a formula I;

wherein R is₁And R₂Each independently selected from C2-C10 alkylene, such as C3, C4, C5, C6, C7, C8, C9, etc., wherein the term "C2-C10" refers to the number of alkylene carbons.

The polyaryletherketone derivative with the structure shown in the formula I has the advantages that molecular chains are stacked more tightly, the methanol permeability can be reduced, meanwhile, alkyl sulfonic acid branched chains on a skeleton of the polyaryletherketone derivative have larger free volume, so that sulfonic acid groups are favorably gathered in pore channels of a metal organic skeleton compound to form a more continuous and wider proton transmission channel, and the proton conductivity of a proton exchange membrane is improved.

The polyaryletherketone derivative is called SNF-PAEK for short.

Preferably, the molecular weight of the polyaryletherketone derivative is 30000-50000g/mol, such as 32000g/mol, 34000g/mol, 36000g/mol, 38000g/mol, 40000g/mol, 42000g/mol, 44000g/mol, 46000g/mol, 48000g/mol and the like.

Preferably, the metal organic framework compound comprises amino-sulfonic acid modified MIL-101.

Preferably, the mass percentage of the metal organic framework compound in the polyaryletherketone derivative is 0.5% -5%, such as 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, etc. Excessive filler can cause excessive physical crosslinking of the polymer substrate, which causes difficulty in micro-movement of polymer molecular chains, is not favorable for proton transmission, and causes reduction of proton conductivity.

In a second aspect, the present invention provides a method for preparing the proton exchange membrane of the first aspect, the method comprising the following steps: and mixing the polyaryletherketone derivative and the metal organic framework compound, dissolving, coating the mixture on a substrate, drying, and stripping the substrate to obtain the proton exchange membrane.

Preferably, the preparation method of the polyaryletherketone derivative comprises the following steps: reacting a polymer (HO-NF-PAEK for short) shown in a formula II with sultone to obtain the polyaryletherketone derivative;

preferably, the reaction temperature is 40-90 degrees C, such as 45 degrees C, 50 degrees C, 55 degrees C, 60 degrees C, 65 degrees C, 70 degrees C, 75 degrees C, 80 degrees C, 85 degrees C.

Preferably, the reaction time is 12-24h, such as 14h, 16h, 18h, 20h, 22h, etc.

Preferably, the preparation method of the polymer shown in the formula II comprises the following steps: performing demethylation reaction on the polymer (NF-PAEK for short) shown in the formula III to obtain the polymer shown in the formula II;

preferably, the solvent for the demethylation reaction comprises chloroform and boron tribromide.

Preferably, the preparation method of the polymer shown in the formula III comprises the following steps: carrying out polycondensation reaction on monomers shown in formulas IV and V to obtain a polymer shown in a formula III;

preferably, the catalyst for the polycondensation reaction comprises potassium carbonate.

Preferably, the solvent of the polycondensation reaction comprises dimethyl sulfoxide (DMSO).

Preferably, the water-carrying agent of the polycondensation reaction comprises toluene.

Preferably, the polycondensation reaction temperature is 120-.

Preferably, the preparation method of the monomer shown in the formula IV comprises the following steps: will be provided with Reacting to obtain a monomer shown in a formula IV;

and X is a halogen atom.

The monomer shown in the formula IV, namely DMNF prepared by the method can graft two sulfonic acid side chains on one monomer, so that higher sulfonic acid group density in a polymer substrate can be realized, the sulfonation rate of the formed polyaryletherketone derivative is higher, and the size stability of the formed proton exchange membrane is better.

Preferably, the solvent of the reaction comprises a combination of chloroform and ferric chloride.

Preferably, the preparation method of the metal organic framework compound comprises the following steps: reacting 2-amino-terephthalic acid with Cr (NO)₃)₃·9H₂And performing hydrothermal reaction on O to form aminated MIL-101, and performing sulfonation reaction on the aminated MIL-101 and alkyl sultone to obtain the metal organic framework compound containing amino and sulfonic acid groups.

Preferably, the temperature of the hydrothermal reaction is 120-.

Preferably, the hydrothermal reaction time is 18-32h, such as 19h, 20h, 22h, 24h, 26h, 28h, 30h, and the like.

Preferably, the hydrothermal reaction is followed by operations of centrifugation, reflux and drying.

Preferably, the temperature of the sulfonation reaction is 80 to 120 ℃, for example, 90 ℃, 95 ℃, 100 ℃, 105 ℃, 110 ℃, 115 ℃ and the like.

Preferably, the sulfonation reaction time is 18-32h, such as 19h, 20h, 22h, 24h, 26h, 28h, 30h, and the like.

Preferably, the sulfonation reaction is followed by operations of centrifugation, reflux, acidification and deacidification.

As a preferred technical scheme, the preparation method comprises the following steps:

(1) preparation of polyaryletherketone derivatives:

will be provided withReacting in chloroform and ferric chloride to obtain a monomer shown in a formula IV;

carrying out polycondensation reaction on the monomers shown in the formulas IV and V at the temperature of 120-180 ℃ to obtain a polymer shown in a formula III;

performing demethylation reaction on the polymer shown in the formula III in chloroform and boron tribromide to obtain a polymer shown in a formula II;

reacting the polymer shown in the formula II with sultone at 40-90 ℃ for 12-24h to obtain polyaryletherketone derivative shown in the formula I;

(2) preparation of metal organic framework compound: reacting 2-amino-terephthalic acid with Cr (NO)₃)₃·9H₂Performing hydrothermal reaction on O at the temperature of 120-200 ℃ for 18-32h, performing operations of centrifugation, reflux and drying to form aminated MIL-101, performing sulfonation on the aminated MIL-101 and alkyl sultone at the temperature of 80-120 ℃ for 18-32h, and performing operations of centrifugation, reflux, acidification and deacidification to obtain a metal organic framework compound containing amino and sulfonic groups;

(3) preparing a proton exchange membrane: mixing and dissolving a polyaryletherketone derivative and a metal organic framework compound, coating the mixture on a substrate, drying, and stripping the substrate to obtain a proton exchange membrane;

wherein the polymer of formula II, the polymer of formula III, the monomer of formula IV and V and X have the same meanings as described above.

In a third aspect, the present invention provides a direct methanol fuel cell comprising the proton exchange membrane of the first aspect.

Compared with the prior art, the invention has the following beneficial effects:

the proton exchange membrane has lower swelling rate and methanol permeability, higher proton conductivity, methanol permeation oxidation current density and limit power densityThe direct methanol fuel cell has good application. The swelling rate of the proton exchange membrane is less than 41.9 +/-9.4 percent, and the proton conductivity is 0.135S-cm^-1Above, the methanol permeability is 7.03X 10^-7cm²·s^-1The following.

Drawings

FIG. 1 is a schematic illustration of the mechanism of the performance improvement of the proton exchange membrane described in examples 1-3;

FIG. 2 is a nuclear magnetic hydrogen spectrum characterization of DMNF as described in example 1;

FIG. 3 is a nuclear magnetic hydrogen spectrum characterization of the NF-PAEK described in example 1;

FIG. 4 is a nuclear magnetic hydrogen spectrum characterization of HO-NF-PAEK as described in example 1;

FIG. 5 is a nuclear magnetic hydrogen spectrum characterization of SNF-PAEK as described in example 1;

FIG. 6 is an SEM image of the MNCS described in example 1;

FIG. 7 shows NH as described in example 1₂-XRD patterns of MIL-101 and MNCS;

FIG. 8 shows NH as described in example 1₂FTIR plots for MIL-101 and MNCS;

FIG. 9 shows NH as described in example 1₂XPS (S, 2p) plots for MIL-101 and MNCS;

FIG. 10 shows NH as described in example 1₂XPS (N, 1s) plots for MIL-101 and MNCS;

FIG. 11a is NH as described in example 1₂EIS map of MIL-101;

FIG. 11b is an EIS diagram of the MNCS described in example 1;

FIG. 12 is a graph of proton conductivity versus temperature for the proton exchange membranes described in examples 1-3 and comparative example 1;

FIG. 13 is a graph of methanol crossover oxidation current density as a function of applied potential for the proton exchange membranes described in examples 1-3 and comparative example 1;

FIG. 14 is an I-V and power density curve for the proton exchange membranes described in example 2 and comparative example 1.

Detailed Description

For the purpose of facilitating an understanding of the present invention, the present invention will now be described by way of examples. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.

Example 1

The embodiment provides a proton exchange membrane, which comprises a polyaryletherketone derivative and a metal organic framework compound;

the main chain of the polyaryletherketone derivative contains fluorine atoms and the side chain contains sulfonic groups;

the metal organic framework compound simultaneously comprises an amino group and a sulfonic group;

the mass percentage of the metal organic framework compound in the polyaryletherketone derivative is 0.5%.

The mechanism diagram of the proton exchange membrane performance improvement is shown in figure 1, and the nuclear magnetic hydrogen spectrum characterization diagrams of the related products in the preparation are shown in figures 2-5.

The preparation method of the proton exchange membrane comprises the following steps:

(1) preparation of polyaryletherketone derivatives:

will be provided withReacting in chloroform and ferric chloride, and refluxing to obtain a monomer shown as a formula IV, namely DMNF, wherein the reaction formula is as follows:

adding 12.970g of DMNF, 1.60g of hexafluorobisphenol A and 4.56g of potassium carbonate into a 250mL three-neck flask with mechanical stirring, water-carrying reflux and nitrogen protection, adding 50mL of solvent DMSO and 10mL of water-carrying agent toluene into the three-neck flask, heating the system to 140 ℃ under the protection of nitrogen to fully dissolve the reactants, stably refluxing the mixed solvent in the water-carrying agent for 3h, removing water generated in the reaction process, slowly discharging the toluene in the system, heating to 180 ℃ for 12h, pouring the thickened solution into a large amount of deionized water to naturally separate out the polymer, further filtering to obtain a crude polymer product, crushing the crude polymer product by using a crusher, repeatedly refluxing and washing by using deionized water to remove the residual solvent and the potassium carbonate, finally placing the polymer powder in an oven at 60 ℃ for 24h and drying to obtain the polymer shown in the formula III, i.e., NF-PAEK, the reaction formula is as follows:

next, 6.0g of NF-PAEK was added to a 250mL three-necked flask with mechanical stirring while ice-bathing and dissolved with 120mL of chloroform, followed by 30mL of boron tribromide (BBr) at a concentration of 1M₃) The dichloromethane solution is slowly and gradually dripped into the solution, a large amount of blood red solid is separated out during the dripping, and the stirring is accelerated. After continuously stirring the suspension for 24 hours at room temperature, pouring the suspension into 500mL of deionized water to quench the reaction, washing the crude product with deionized water for multiple times by refluxing, filtering, collecting and drying in an oven at 60 ℃ to obtain a polymer shown as a formula II, namely HO-NF-PAEK, wherein the reaction formula is as follows:

next, 5.0g of HO-NF-PAEK was added to a 100mL three-necked flask with mechanical stirring and nitrogen blanketing and dissolved with 50mL DMSO. The system is warmed to 40 ℃ and 0.7g of NaH is then added rapidly to the solution, after a further 20 minutes of continuous stirring 6.0g of 1, 4-butylsultone are added to the solution, and the grafting reaction is continued for 12 hours at 90 ℃ and the mixture is poured into 500mL of acetone to precipitate the product. Repeatedly refluxing and washing the product with acetone, drying, and then acidifying the product with a hydrochloric acid solution with the concentration of 1M to obtain a polyaryletherketone derivative shown as I, namely SNF-PAEK, wherein the reaction formula is as follows:

(2) preparation of metal organic framework compound:

respectively taking 4.0g of Cr (NO)₃)₃9H2O, 1.66g of NH₂-H₂Adding BDC and 0.40g NaOH into a beaker filled with 120mL deionized water, magnetically stirring for 1h to completely dissolve reactants, pouring the mixed solution into a stainless steel reaction kettle with a polytetrafluoroethylene lining, and putting the reaction kettle into a 160 ℃ drying oven for hydrothermal synthesis reaction;

closing the heating after 24 hours, naturally cooling the reaction kettle to room temperature, collecting a crude product through centrifugation, repeatedly washing the crude product through reflux of DMF (dimethyl formamide), deionized water and ethanol for a plurality of times, and removing raw materials which do not participate in the reaction; further placing the solid obtained by centrifugation in a drying oven at 150 ℃ for 24 hours to obtain NH₂-MIL-101；

2.0g of NH were then weighed₂MIL-101 powder, dispersed in 30mL anhydrous DMF, added to a round bottom flask with nitrogen blanket; the temperature of the system was raised to 40 ℃ by heating in an oil bath, and 0.22g of CH was added to the system₃ONa, after reacting for 40 minutes, 0.9g of 1, 3-propane sultone is added into the system dropwise; after the system is heated to 100 ℃ and reacted for 24 hours, the mixture is poured into 500mL of acetone to stop the reaction;

after collecting the crude product by centrifugation, it was purified by repeated reflux with acetone several times and 1M H₂SO₄Acidifying inorganic powder, finally repeatedly washing with deionized water to remove acid liquor adsorbed in pores of the metal organic framework compound, centrifugally collecting a final product, and drying in a vacuum oven at 80 ℃ for 24 hours to finally obtain the metal organic framework compound containing amino and sulfonic groups, namely the MNCS inorganic nano filler;

(3) preparing a proton exchange membrane: dissolving SNF-PAEK in DMAc solvent according to the proportion of 1g/10mL to form a membrane casting solution, adding 0.005g of MNCS inorganic nano filler into 10mL of the membrane casting solution, and carrying out rapid shearing and ultrasonic mixing to form uniform dispersion liquid; the dispersion was then cast on a clean flat area of 15cm²Placing the square glass plate in a 60 ℃ oven for 24 hours to obtain a composite film, placing the composite film taken off from the glass plate in a 140 ℃ vacuum oven for 4 hours, and removing residual in the filmAnd (4) solvent to obtain the proton exchange membrane.

Example 2

This example differs from example 1 in that the weight percentage of the metal organic framework compound in the polyaryletherketone derivative is 1.5%, the amount of the MNCS inorganic nanofiller added during the preparation is 0.015g, and the rest is the same as example 1.

Example 3

This example is different from example 1 in that the weight percentage of the metal organic framework compound in the polyaryletherketone derivative is 3%, the amount of the MNCS inorganic nanofiller added in the preparation is 0.03g, and the rest is the same as example 1.

Comparative example 1

This comparative example differs from example 1 in that no metal-organic framework compound is added, and the rest is the same as example 1.

Performance testing

The proton exchange membranes described in examples 1-3 and comparative example 1 were tested as follows:

(1) swelling ratio test in methanol aqueous solution: firstly, four groups of sample films are placed in a vacuum oven to be dried and then cut into rectangular samples with the size of 30mm multiplied by 30mm, and the actual areas of different samples in a dry state before testing are respectively recorded (A)_dry；cm²)；

Simulating the actual working condition of the fuel cell, soaking the sample in 2M methanol solution, heating in water bath to keep the test temperature at 80 ℃, and recording the actual area (A) of the sample in a wet state after 24 hours_wet；cm²). The experiment was repeated three times, and the results were averaged, and the calculation formula is as follows:

SR＝(A_wet-A_dry)/A_dry×100％。

(2) proton conductivity test: each composite film sample to be measured was cut into 3 rectangular sample strips of 4cm × 1cm in size, and the actual thickness (cm) of each sample strip in a fully wet state at different temperatures was measured. The surface resistance (omega) of the sample under the full-wet state at different temperatures in the scanning frequency range of 1Hz to 1MHz is tested by a Princeton Applied Research Model 2273 electrochemical workstation and a four-electrode AC impedance method. Calculated according to the following formulaCalculating the proton conductivity, wherein L is the distance (cm) between two electrodes, R is the surface resistance (omega) of the sample to be measured, and A is the cross-sectional area (cm) of the sample membrane to be measured²)：

σ＝L/(R×A)。

(3) The methanol permeability of each set of sample membranes was tested in an assembled cell using linear voltammetry (LSV). 2M methanol solution was introduced at the anode of the cell while the cathode of the cell was protected with pre-humidified nitrogen. The cathode is used as a working electrode, the anode is used as a reference electrode, and the methanol permeability can be calculated according to the formula:

P＝L×CD_max/(6F×k×C_fuel)；

wherein P (cm)²·s^-1) Represents the methanol permeability of the proton exchange membrane, L (cm) is the thickness of the membrane, CD_max(mA·cm^-2) Is the limit oxidation current density measured by the LSV method, F is the Faraday constant, C_fuel(M) actual concentration of methanol fuel, k is a correction factor at different methanol fuel concentrations, and k is 0.739 when the methanol concentration is 2M.

(4) Testing the performance of the single battery: the assembled cells were tested for polarization curves using the fuel cell test platform from Arbin corporation. The anode fuel was 2M methanol solution with a flux of 2mL min^-1(ii) a The cathode is humidified oxygen, and the flux is 30 mL-min^-1. The anode catalyst is Hispec6000 with Pt-Ru/C ratio of 60 percent and the loading capacity of 3mg cm^-2(ii) a The cathode electrode catalyst is Hispec 9100 with Pt/C ratio of 60%, and the loading capacity is 2mg cm^-2(ii) a The test was carried out at 80 ℃.

(5) And (3) basic performance characterization: reacting NH₂MIL-101 and MNCS were characterized by SEM, XRD, FTIR, XPS and EIS.

The test results are summarized in table 1 and fig. 6-14.

TABLE 1

Analysis of the data in Table 1 reveals that swelling of the proton exchange membrane of the present inventionThe ratio is 41.9 + -9.4% or less, and the proton conductivity is 0.135S-cm^-1Above, the methanol permeability is 7.03X 10^-7cm²·s^-1The proton exchange membrane has the advantages of low swelling rate, high proton conductivity, low methanol permeability and high ultimate power density, has excellent dimensional stability and high sulfonation rate, and is well applied to direct methanol fuel cells.

As is clear from the analysis of comparative example 1 and example 1, comparative example 1 is inferior in performance to example 1, and it is confirmed that the proton exchange membrane obtained without adding the metal-organic framework compound or without including both the amino group and the sulfonic acid group in the metal-organic framework compound is inferior in performance.

The proton exchange membrane performance modification mechanism of the invention is shown in figure 1, and specifically comprises the following steps: the acid-base ion pair acting force between the MNCS filler and the SNF-PAEK base material forms ion crosslinking, so that the dimensional stability and the alcohol resistance of the membrane are obviously improved. Meanwhile, the flexible alkyl sulfonic acid branched chain grafted on the MNCS framework can freely swing in the pore channel of the MOF, the free volume of the branched chain is larger, sulfonic acid groups can be favorably gathered in the pore channel of the MOF to form a more continuous and wide proton transmission channel, and the proton conductivity of the proton exchange membrane is improved.

FIGS. 6-11 are NH₂Basic characterization of two metal-organic framework compounds, MIL-101 and MNCS, demonstrated successful synthesis of MNCS, and analysis of FIGS. 11a and 11b revealed that the conductivity of MNCS is significantly lower than that of NH₂MIL-101, which is due to the sulfonic acid side chains grafted on MNCS forming continuous proton transport channels, reducing the transport resistance of protons within the inorganic filler.

As can be seen from the analysis of FIGS. 12-14, the proton conductivity of comparative example 1 is inferior to that of examples 1-2, the methanol permeability is inferior to that of examples 1-3, and the power density is inferior to that of example 2, which proves that the proton exchange membrane of the present invention has high proton conductivity, methanol permeation oxidation current density and limiting power density.

In conclusion, the proton exchange membrane has lower swelling rate and methanol permeability, higher proton conductivity, methanol permeation oxidation current density and limiting power density, and has good application in direct methanol fuel cells.

The applicant states that the present invention is illustrated in detail by the above examples, but the present invention is not limited to the above detailed methods, i.e. it is not meant that the present invention must rely on the above detailed methods for its implementation. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.