Polynorbornene-based composite anion exchange membrane as well as preparation method and application thereof

Abstract

The invention discloses a polynorbornene-based composite anion exchange membrane and a preparation method and application thereof, the composite anion exchange membrane comprises polysulfone resin and ionic polynorbornene, or the composite anion exchange membrane comprises polybenzimidazole resin and ionic polynorbornene, or the composite anion exchange membrane comprises polybenzimidazole resin and ionic polynorbornene, or the composite anion exchange membrane comprises polybenzimidazole resin and ionic polynorbornene. The composite material comprises polysulfone resin, polybenzimidazole resin and ionic polynorbornene. According to the polynorbornene-based composite anion exchange membrane disclosed by the invention, the polysulfone resin or the polybenzimidazole resin is introduced into the ionic polynorbornene, so that the mechanical strength of the anion exchange membrane in a wet membrane state can be remarkably improved, the polynorbornene-based composite anion exchange membrane can be used for assembling a more stable water electrolysis device, and the durability is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of anion exchange membrane preparation, and particularly relates to a polynorbornene-based composite anion exchange membrane and a preparation method and application thereof. BACKGROUND

[0002] Hydrogen energy, because it only produces water when burning or generating electricity through a fuel cell, and does not emit carbon dioxide, has become a key carrier to achieve the global carbon neutral vision. The process of using renewable power to drive water electrolysis to prepare hydrogen and oxygen is called "green hydrogen" preparation. Among the many water electrolysis technology routes, anion exchange membrane (AEM) water electrolysis for hydrogen production is considered to be the most potential large-scale green hydrogen production technology of the next generation because it combines the low-cost material system of an alkaline electrolyzer and the high efficiency and fast response advantages of a proton exchange membrane (PEM) electrolyzer.

[0003] Anion exchange membrane water electrolysis (AEMWE) and anion exchange membrane fuel cells (AEMFC) can use non-noble metal catalysts and have faster cathode reaction kinetics, and are key devices for effective hydrogen production and utilization. Anion exchange membrane (AEM) is one of the key components of AEMFC and AEMWE, and has a crucial influence on the performance and durability of the equipment. As a kind of polymer material, AEM is mainly composed of a polymer skeleton, covalently bonded cationic functional groups, and freely moving anions. Among the many controllable selected polymer skeletons, polynorbornene has a fully carbon hydrogen main chain structure, and thus has excellent thermal stability and chemical stability; at the same time, because it does not contain a benzene ring structure, it becomes a promising AEM skeleton, and compared to a polyaryl skeleton synthesized through super acid catalysis, the synthesis process of polynorbornene is under all neutral conditions, and does not need to use super acid such as triflic acid as a solvent, so that secondary problems such as equipment corrosion and environmental pollution can be avoided.

[0004] However, a major problem of the current poly-norbornene-based AEM is its insufficient anti-swelling performance and mechanical properties. Due to the lack of strong intermolecular interactions such as benzene rings in the structure of poly-norbornene, the AEM is prone to excessive water absorption and swelling after the introduction of ionic functional groups, which will further reduce its mechanical properties. Therefore, a common strategy is to control water absorption and swelling by introducing a cross-linked structure. For example, Kohl et al. (ACS Appl. Energy Mater. 2019, 2, 2447-2457) used a diamine cation to cross-link, but the swelling could not be effectively controlled, so a porous polytetrafluoroethylene (PTFE) substrate was further introduced for composite enhancement. However, due to the slow diffusion speed of the polymer material in the porous substrate, it cannot be completely filled, which will also cause the gas barrier performance of the composite ion exchange membrane based on the porous substrate to be poor. In addition, there is also a strategy of ultraviolet cross-linking based on dithiol (J. Membr. Sci. 2024, 702, 122747|1-10; CN117229451B). This series of ion exchange membranes has high ionic conductivity, but the mechanical properties are poor, with a tensile breaking strength and strain of 36 MPa and 19% in the dry state, which will further decrease under wet conditions, and cannot withstand the assembly strength and gas barrier requirements of ion exchange membranes in electrochemical devices.

[0005] Therefore, how to improve the mechanical strength of AEM while ensuring its high conductivity and prolong the service life of AEM is a technical problem to be solved. SUMMARY

[0006] In view of the deficiencies of the prior art, the purpose of the present application is to provide a poly-norbornene-based composite anion exchange membrane and a preparation method and application thereof. The composite anion exchange membrane has significantly improved breaking strain under wet conditions, and improved gas barrier performance after long-term stability test, ensuring that the device can operate stably for a long time, and has a good development prospect.

[0007] Based on this, the technical solutions of the present application are as follows: A poly-norbornene-based composite anion exchange membrane comprises a polysulfone resin and an ionic poly-norbornene, or comprises a polybenzimidazole resin and an ionic poly-norbornene, or comprises a polysulfone resin, a polybenzimidazole resin and an ionic poly-norbornene.

[0008] According to an embodiment of the present application, the mass ratio of the polysulfone resin to the ionic poly-norbornene is 1:1-20, preferably 1:2-10.

[0009] According to an embodiment of the present application, the mass ratio of the polybenzimidazole resin to the ionic poly-norbornene is 1:1-20, preferably 1:2-10.

[0010] According to the embodiments of the present application, the polysulfone resin refers to a kind of polymer containing sulfone groups in the molecular backbone, and aromatic rings (such as benzene rings) are connected on both sides. For example, the polysulfone resin is selected from at least one of bisphenol A polysulfone (PSU), ether-containing polyethersulfone (PES), polyphenyl sulfone containing biphenyl (PPSU), polyphenylene sulfone containing phenyl (PPSO2), polyaryl sulfone containing multiple aromatic rings and heteroatoms (such as ketone groups) (PASF) and the like.

[0011] Preferably, the number average molecular weight of the polysulfone resin is 20,000-100,000.

[0012] According to the embodiments of the present application, the ionic poly norbornene refers to a polymer containing a poly norbornene high molecular backbone, and the side chain contains a quaternary ammonium cation functional group. Specifically, the quaternary ammonium cation functional group includes but is not limited to alkyl-trimethylamine cation, alkyl-N-methyl piperidine cation and the like. Further specifically, the poly norbornene high molecular backbone refers to a polymer backbone obtained by taking bicyclo[2.2.1]-2-heptene as the core structure and norbornene and its derivatives as monomers. For example, the ionic poly norbornene is prepared according to the method in CN202411264129.3.

[0013] Preferably, the number average molecular weight of the ionic poly norbornene is 20,000-500,000.

[0014] Preferably, the ion exchange capacity of the ionic poly norbornene is 0.5-3.0 mmol / g, and further preferably 1.5-2.5 mmol / g.

[0015] According to the embodiments of the present application, the polybenzimidazole resin (PBI) refers to a kind of polymer containing benzimidazole repeating units in the molecular backbone. For example, the PBI includes but is not limited to at least one of poly[2,2'-(m-phenylene)-5,5'-benzimidazole] (mPBI), poly[2,5-(1,3-phenylene) benzimidazole] (ABPBI), poly(2,2'-diphenyl ether-5,5'-benzimidazole) (OPBI), poly(2,2'-diphenyl sulfone-5,5'-benzimidazole) (SPBI), poly(2,2'-hexafluoroisopropyl-5,5'-benzimidazole) (HFIP-PBI), poly(4,4'-diphenyl imidazole-2,2'-diethylhexane) and the like.

[0016] Preferably, the number average molecular weight of the polybenzimidazole resin is in the range of 20,000-100,000.

[0017] The present application also provides a preparation method of the above-mentioned poly norbornene-based composite anion exchange membrane, which comprises: The poly sulfone resin solution or the poly benzimidazole resin solution is mixed with the ionic poly norbornene solution, and the obtained mixed solution is formed into a film to prepare the composite anion exchange membrane.

[0018] According to an embodiment of the present application, the poly sulfone resin solution refers to dissolving poly sulfone resin in a polar organic solvent, and the concentration of the poly sulfone resin solution is 1-10 wt%, preferably 1-5 wt%.

[0019] According to an embodiment of the present application, the poly benzimidazole resin solution refers to dissolving poly benzimidazole resin in a polar organic solvent, and the concentration of the poly benzimidazole resin solution is 1-10 wt%, preferably 1-5 wt%.

[0020] According to an embodiment of the present application, the ionic poly norbornene solution refers to dissolving ionic poly norbornene in a polar organic solvent, and the concentration of the ionic poly norbornene solution is 1-25 wt%, preferably 5-15 wt%.

[0021] Preferably, the polar organic solvent is at least one selected from N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), and N-methyl pyrrolidone (NMP).

[0022] According to an embodiment of the present application, the mixed solution is formed into a film by solution evaporation, which is casting the solution into a mold or uniformly coating the solution on a flat substrate, and then drying at 80-120 °C. The time for film formation is not particularly limited, as long as the mixed solution can be formed into a film.

[0023] As an exemplary embodiment of the present application, the preparation method of the poly norbornene-based composite anion exchange membrane specifically comprises the following steps: Step A: dissolving poly sulfone resin or poly benzimidazole resin in a polar organic solvent at a mass fraction of 1-10% to obtain solution A; Step B: dissolving ionic poly norbornene resin in a polar organic solvent at a mass fraction of 1-25% to obtain solution B; Step C: uniformly mixing solution A and solution B to obtain solution C; Step D: forming solution C into a film by solution evaporation to obtain the composite anion exchange membrane.

[0024] The present application also provides the use of the above-mentioned poly norbornene-based composite anion exchange membrane in anion exchange membrane electrolysis water or an anion exchange membrane fuel cell.

[0025] The present application has the following advantages: (1) The poly(norbornene)-based composite anion exchange membrane of the present application is obtained by introducing a polysulfone resin or a polybenzimidazole resin into an ionic poly(norbornene), and the composite anion exchange membrane has significantly improved mechanical strength in a wet membrane state, and can be used to assemble a more stable water electrolysis device, i.e., the water electrolysis device has significantly improved durability.

[0026] (2) The present application still maintains high ionic conductivity of the prepared composite anion exchange membrane by optimizing the ratio of the two polymer components. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is a tensile stress-strain curve comparison chart of the anion exchange membrane samples in Examples 1-3 and Comparative Example 1.

[0028] Figure 2 is a water electrolysis performance comparison chart of the anion exchange membrane samples in Example 1 and Comparative Example 1.

[0029] Figure 3 is a tensile stress-strain curve comparison chart of the anion exchange membrane samples in Examples 4-6 and Comparative Example 1.

[0030] Figure 4 is a water electrolysis performance comparison chart of the anion exchange membrane samples in Example 4 and Comparative Example 1. DETAILED DESCRIPTION

[0031] The technical solutions of the present application will be further described in detail below in conjunction with specific examples. It should be understood that the following examples are only illustratively described and explained, and should not be interpreted as limiting the scope of protection of the present application. Any technology realized based on the above description of the present application is covered within the scope of protection intended by the present application.

[0032] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0033] Example 1 First, 1 g of PSU polysulfone was dissolved in 100 mL of DMAc solution to form a uniform solution. Then, 10 g of the ionic norbornene prepared according to Example 4 of Patent 2024112641293 was dissolved in 100 mL of DMAc solution to form a uniform solution. The two solutions were mixed uniformly to form a mixed solution, and a uniform composite anion exchange membrane was prepared by solvent evaporation at 100 °C.

[0034] Example 2 Firstly, 2 g PSU polysulfone was dissolved in 100 mL DMAc solution to configure a uniform solution. Then 10 g of ion-type norbornene prepared according to the preparation method of Example 4 in patent 2024112641293 was dissolved in 100 mL DMAc solution to configure a uniform solution. The two solutions were mixed uniformly to form a mixed solution, and a uniform composite anion exchange membrane was prepared by solvent evaporation at 100 °C.

[0035] Example 3 Firstly, 3 g PSU polysulfone was dissolved in 100 mL DMAc solution to configure a uniform solution. Then 10 g of ion-type norbornene prepared according to the preparation method of Example 4 in patent 2024112641293 was dissolved in 100 mL DMAc solution to configure a uniform solution. The two solutions were mixed uniformly to form a mixed solution, and a uniform composite anion exchange membrane was prepared by solvent evaporation at 100 °C.

[0036] Example 4 Firstly, 1 g mPBI was dissolved in 100 mL DMAc solution to configure a uniform solution. Then 10 g of ion-type norbornene prepared according to the preparation method of Example 4 in patent 2024112641293 was dissolved in 100 mL DMAc solution to configure a uniform solution. The two solutions were mixed uniformly to form a mixed solution, and a uniform composite anion exchange membrane was prepared by solvent evaporation at 100 °C.

[0037] Example 5 Firstly, 2 g mPBI was dissolved in 100 mL DMAc solution to configure a uniform solution. Then 10 g of ion-type norbornene prepared according to the preparation method of Example 4 in patent 2024112641293 was dissolved in 100 mL DMAc solution to configure a uniform solution. The two solutions were mixed uniformly to form a mixed solution, and a uniform composite anion exchange membrane was prepared by solvent evaporation at 100 °C.

[0038] Example 6 Firstly, 3 g mPBI was dissolved in 100 mL DMAc solution to configure a uniform solution. Then 10 g of ion-type norbornene prepared according to the preparation method of Example 4 in patent 2024112641293 was dissolved in 100 mL DMAc solution to configure a uniform solution. The two solutions were mixed uniformly to form a mixed solution, and a uniform composite anion exchange membrane was prepared by solvent evaporation at 100 °C.

[0039] Comparative Example 1 The ionotropic norbornene 10 g prepared according to the embodiment 4 in the patent 2024112641293 was dissolved in 100 mL of DMAc solution, configured into a uniform solution, and prepared into a uniform anion exchange membrane by solvent evaporation at 100 °C.

[0040] Test Example 1 The mechanical properties of the anion exchange membranes in Examples 1-6 and Comparative Example 1 were measured under the following test conditions: the anion exchange membrane sample to be tested was soaked in distilled water for 24 h, covered with absorbent paper after being fished out and dried for 3 min, and then subjected to tensile testing at a tensile rate of 0.2 mm / min at room temperature. The test was measured 5 times, and the average value was calculated from the test results of the middle 3 groups. The test results are shown in Table 1. The tensile strain curve is shown in Figure 1 and Figure 3 .

[0041] Test Example 2 The bicarbonate ion conductivity of the anion exchange membranes in Examples 1-6 and Comparative Example 1 was measured under the following test conditions: the ion exchange membrane sample was soaked in a NaHCO3 aqueous solution to replace the bicarbonate ion, and then subjected to conductivity testing after being washed with deionized water. The resistance of the membrane was measured using electrochemical impedance spectroscopy, and then the conductivity was calculated by formula (1). The test results are shown in Table 1.

[0042] Formula (1) Test Example 3 The electrolysis water performance of the anion exchange membranes in Examples 1, 4 and Comparative Example 1 was measured under the following test conditions: the anode catalyst was NiFe, and the anode substrate was nickel foam; the cathode catalyst was Pt / C, and the cathode substrate was carbon paper. The catalyst sheet was cut into 2.0 cm x 2.0 cm, and the effective area of the electrolytic cell was 2.0 cm x 2.0 cm. The concentration of the electrolyte KOH aqueous solution was 1.0 M. The electrolysis water test was carried out for 110 hours, and the test results are shown in Figure 2 and Figure 4 .

[0043] Table 1 Comparison of mechanical properties and ion conductivity of anion exchange membranes in Examples 1-6 and Comparative Example 1

[0044] The above has exemplarily described the embodiments of the present application. However, the protection scope of the present application is not limited to the above-mentioned embodiments. Any modification, equivalent replacement, improvement, etc. made by those skilled in the art within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A polynorbornene-based composite anion exchange membrane, characterized by, The composite anion exchange membrane comprises a polysulfone resin and an ionic polynorbornene, or the composite anion exchange membrane comprises a polybenzimidazole resin and an ionic polynorbornene, or the composite anion exchange membrane comprises a polysulfone resin, a polybenzimidazole resin and an ionic polynorbornene; The mass ratio of the polysulfone resin and the ionic polynorbornene is 1:1-20; The mass ratio of the polybenzimidazole resin and the ionic polynorbornene is 1:1-20.

2. The composite anion exchange membrane according to claim 1, characterized by, The polysulfone resin refers to a kind of polymer containing sulfone group in the molecular main chain, and the aromatic ring is connected on both sides of the polymer; And / or, the polysulfone resin is selected from at least one of bisphenol A polysulfone, ether bond-containing polyether sulfone, polyphenyl sulfone containing biphenyl, polyphenylene sulfone containing phenyl, and polyaryl sulfone containing multiple aromatic rings and heteroatoms; And / or, the number average molecular weight of the polysulfone resin is 20,000-100,000.

3. The composite anion exchange membrane according to claim 1, characterized by, The ionic polynorbornene comprises a polymer of a polynorbornene high molecular backbone, and the side chain contains a quaternary ammonium cation functional group, wherein the quaternary ammonium cation functional group is selected from at least one of alkyl-trimethylamine cation and alkyl-N-methyl piperidine cation; And / or, the polynorbornene high molecular backbone refers to a polymer main chain obtained by using bicyclo[2.2.1]-2-heptene as a core structure and norbornene and its derivatives as monomers.

4. The composite anion exchange membrane according to claim 1, characterized by, The number average molecular weight of the ionic polynorbornene is 20,000-500,000; And / or, the ion exchange capacity of the ionic polynorbornene is 0.5-3.0 mmol / g.

5. The composite anion exchange membrane according to claim 1, wherein The polybenzimidazole resin refers to a kind of polymer containing benzimidazole repeating units in the molecular main chain; And / or, the polybenzimidazole resin is selected from at least one of poly[2,2'-(m-phenylene)-5,5'-benzimidazole], poly[2,5-(1,3-phenylene) benzimidazole], poly(2,2'-diphenyl ether-5,5'-benzimidazole), poly(2,2'-diphenyl sulfone-5,5'-benzimidazole), poly(2,2'-hexafluoroisopropyl-5,5'-benzimidazole), and poly(4,4'-benzimidazole-2,2'-diethylhexane); And / or, the number average molecular weight of the polybenzimidazole resin is 20,000-100,000.

6. The method for producing a composite anion exchange membrane according to any one of claims 1 to 5, characterized by, The method comprises: Mixing a polysulfone resin solution or a polybenzimidazole resin solution with an ionic polynorbornene solution, and forming a film from the obtained mixed solution to prepare the composite anion exchange membrane.

7. The method of claim 6, wherein, The polysulfone resin solution refers to dissolving the polysulfone resin in a polar organic solvent, and the concentration of the polysulfone resin solution is 1-10 wt%.

8. The method of claim 6, wherein, The polybenzimidazole resin solution refers to dissolving the polybenzimidazole resin in a polar organic solvent, and the concentration of the polybenzimidazole resin solution is 1-10 wt%.

9. The method of claim 6, wherein, The ionic polynorbornene solution refers to dissolving the ionic polynorbornene in a polar organic solvent, and the concentration of the ionic polynorbornene solution is 1-25 wt%; And / or, the polar organic solvent is selected from at least one of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and N-methyl pyrrolidone.

10. The application of the anion exchange membrane according to any one of claims 1-5 in anion exchange membrane water electrolysis or anion exchange membrane fuel cell.

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