A polynorbornene-based composite anion exchange membrane, a preparation method and application thereof
By introducing polysulfone or polybenzimidazole resin into polynorbornene-based anion exchange membranes, optimizing the component ratio, and employing a solution evaporation film-forming method, the swelling and gas barrier properties of polynorbornene-based membranes were solved, resulting in improved high conductivity and mechanical strength, making them suitable for stable operation of water electrolysis devices.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- INST OF CHEM CHINESE ACAD OF SCI
- Filing Date
- 2026-01-29
- Publication Date
- 2026-05-12
AI Technical Summary
Existing polynorbornene-based anion exchange membranes are prone to excessive water absorption and swelling after the introduction of ionic functional groups, leading to a decline in mechanical properties. Furthermore, the porous substrate composite membranes have poor gas barrier properties and cannot meet the stability requirements of electrochemical devices.
By introducing polysulfone resin or polybenzimidazole resin and ionic polynorbornene to optimize their mass ratio, a composite anion exchange membrane is prepared using a solution evaporation film-forming method, thereby improving the membrane's mechanical strength and gas barrier properties.
It significantly improves the mechanical strength and long-term stability in the wet film state, maintains high ionic conductivity, and is suitable for stable operation of water electrolysis devices.
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Figure CN121574485B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of anion exchange membrane preparation technology, specifically relating to a polynorbornene-based composite anion exchange membrane, its preparation method, and its application. Background Technology
[0002] Hydrogen energy, because it produces only water and no carbon dioxide when burned or used to generate electricity through fuel cells, has become a key vehicle for achieving the global vision of carbon neutrality. The process of producing hydrogen and oxygen by electrolyzing water using renewable electricity is known as "green hydrogen" production. Among the many water electrolysis technologies, anion exchange membrane (AEM) electrolysis for hydrogen production is considered the most promising next-generation large-scale green hydrogen production technology due to its combination of the low-cost material system of alkaline electrolyzers and the high efficiency and rapid response of proton exchange membrane (PEM) electrolyzers.
[0003] Anion exchange membrane electrolysis (AEMWE) and anion exchange membrane fuel cells (AEMFC) can use non-precious metal catalysts and have relatively fast cathode reaction kinetics, making them key devices for the efficient production and utilization of hydrogen. The anion exchange membrane (AEM) is a crucial component of AEMFC and AEMWE, significantly impacting the performance and durability of the equipment. As a polymer material, AEM mainly consists of a polymer backbone, covalently linked cationic functional groups, and freely moving anions. Among many controllable polymer backbones, polynorbornene possesses an all-carbon-hydrogen backbone structure, thus exhibiting excellent thermal and chemical stability. Furthermore, its absence of benzene rings makes it a promising AEM backbone. Compared to polyaryl backbones catalyzed by superacids, the synthesis of polynorbornene is conducted under completely neutral conditions, eliminating the need for superacids such as trifluoromethanesulfonic acid as solvents, thereby avoiding secondary problems such as equipment corrosion and environmental pollution.
[0004] However, a major problem with polynorbornene-based AEMs is their insufficient anti-swelling and mechanical properties. Due to the lack of strong inter-chain interactions such as benzene rings in the polynorbornene structure, it easily absorbs water and swells excessively after the introduction of ionic functional groups, leading to a further decrease in its mechanical properties. Therefore, a common strategy is to control water absorption and swelling by introducing cross-linking structures. For example, Kohl et al. (ACS Appl. Energy Mater. 2019, 2, 2447-2457) used diamine cations for cross-linking, but this still could not effectively control swelling. Therefore, further composite reinforcement using a porous polytetrafluoroethylene (PTFE) substrate is needed. However, because the polymer material diffuses slowly in the porous substrate, it cannot be completely filled, which also leads to poor gas barrier properties in such porous substrate-based composite ion exchange membranes. Another strategy is a dithiol-based UV crosslinking strategy (J. Membr. Sci. 2024, 702, 122747|1-10; CN117229451B). This series of ion exchange membranes has high ionic conductivity, but poor mechanical properties. Its tensile breaking strength and strain in the dry state are 36 MPa and 19%, respectively, which will further decrease under wet conditions. It cannot meet the assembly strength and barrier gas requirements of ion exchange membranes in electrochemical devices.
[0005] Therefore, how to improve the mechanical strength and extend the service life of AEM while ensuring its high electrical conductivity is an urgent technical problem to be solved. Summary of the Invention
[0006] To address the shortcomings of existing technologies, the present invention aims to provide a polynorbornene-based composite anion exchange membrane, its preparation method, and its application. The composite anion exchange membrane exhibits significantly improved fracture strain under wetted conditions and improved gas barrier performance after long-term stability testing, ensuring stable operation of the device over extended periods and demonstrating promising development prospects.
[0007] Based on this, the technical solution of the present invention is as follows:
[0008] A polynorbornene-based composite anion exchange membrane comprises a polysulfone resin and ionic polynorbornene, or comprises a polybenzimidazole resin and ionic polynorbornene, or comprises a polysulfone resin, a polybenzimidazole resin and ionic polynorbornene.
[0009] According to an embodiment of the present invention, the mass ratio of the polysulfone resin to the ionic polynorbornene is 1:1 to 20, preferably 1:2 to 10.
[0010] According to an embodiment of the present invention, the mass ratio of the polybenzimidazole resin to the ionic polynorbornene is 1:1 to 20, preferably 1:2 to 10.
[0011] According to embodiments of the present invention, the polysulfone resin refers to a class of polymers whose molecular backbone contains sulfone groups and whose sides are connected with aromatic rings (e.g., benzene rings). For example, the polysulfone resin is selected from at least one of bisphenol A polysulfone (PSU), polyether sulfone (PES) containing ether bonds, polyphenyl sulfone (PPSU) containing biphenyl groups, polyphenylene sulfone (PPSO2) containing phenyl groups, and polyarylsulfone (PASF) containing various aromatic rings and heteroatoms (such as ketone groups).
[0012] Preferably, the number-average molecular weight of the polysulfone resin is 20,000 to 100,000.
[0013] According to an embodiment of the present invention, the ionic polynorbornene is a polymer comprising a polynorbornene polymer backbone, the side chains of which contain quaternary ammonium cationic functional groups. Specifically, the quaternary ammonium cationic functional groups include, but are not limited to, alkyl-trimethylamine cations, alkyl-N-methylpiperidine cations, etc. More specifically, the polynorbornene polymer backbone refers to a polymer backbone obtained using norbornene and its derivatives as monomers with a bicyclic [2.2.1]-2-heptene as the core structure. For example, the ionic polynorbornene is prepared according to the method in CN202411264129.3.
[0014] Preferably, the number-average molecular weight of the ionic polynorbornene is 20,000 to 500,000.
[0015] Preferably, the ion exchange capacity of the ionic polynorbornene is 0.5-3.0 mmol / g, and more preferably 1.5-2.5 mmol / g.
[0016] According to embodiments of the present invention, the polybenzimidazole resin (PBI) refers to a class of polymers containing repeating benzimidazole units in the main molecular chain. For example, the PBI includes, but is not limited to, at least one of poly[2,2'-(m-phenylene)-5,5'-dibenzimidazole] (mPBI), poly[2,5-(1,3-phenylene)benzimidazole] (ABPBI), poly(2,2'-diphenyl ether-5,5'-dibenzimidazole) (OPBI), poly(2,2'-diphenyl sulfone-5,5'-dibenzimidazole) (SPBI), poly(2,2'-hexafluoroisopropyl-5,5'-dibenzimidazole) (HFIP-PBI), and poly(4,4'-dibenzimidazole-2,2'-diethylhexane).
[0017] Preferably, the number-average molecular weight of the polybenzimidazole resin is in the range of 20,000 to 100,000.
[0018] This invention also provides a method for preparing the above-mentioned polynorbornene-based composite anion exchange membrane, the method comprising:
[0019] The composite anion exchange membrane is prepared by mixing a polysulfone resin solution or a polybenzimidazole resin solution with an ionic polynorbornene solution and forming the resulting mixed solution into a film.
[0020] According to an embodiment of the present invention, the polysulfone resin solution refers to polysulfone resin dissolved in a polar organic solvent, and the concentration of the polysulfone resin solution is 1 to 10 wt%, preferably 1 to 5 wt%.
[0021] According to an embodiment of the present invention, the polybenzimidazole resin solution refers to polybenzimidazole resin dissolved in a polar organic solvent, and the concentration of the polybenzimidazole resin solution is 1-10 wt%, preferably 1-5 wt%.
[0022] According to an embodiment of the present invention, the ionic polynorbornene solution refers to ionic polynorbornene dissolved in a polar organic solvent, wherein the concentration of the ionic polynorbornene solution is 1-25 wt%, preferably 5-15 wt%.
[0023] Preferably, the polar organic solvent is selected from at least one of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), and N-methylpyrrolidone (NMP).
[0024] According to an embodiment of the present invention, the mixed solution is formed by solution evaporation. This film formation involves casting the solution into a mold or uniformly coating the solution onto a flat substrate and drying it at 80-120 °C. The film formation time is not particularly limited, as long as the mixed solution can form a film.
[0025] As an exemplary embodiment of the present invention, the preparation method of the polynorbornene-based composite anion exchange membrane specifically includes the following steps:
[0026] Step A: Dissolve polysulfone resin or polybenzimidazole resin in a polar organic solvent at a mass fraction of 1-10% to obtain solution A;
[0027] Step B: Dissolve the ionic polynorbornene resin in a polar organic solvent at a mass fraction of 1-25% to obtain solution B;
[0028] Step C: Mix solution A and solution B thoroughly to obtain solution C;
[0029] Step D: Solution C is used to form a film by solution evaporation to obtain the composite anion exchange membrane.
[0030] The present invention also provides the application of the above-mentioned polynorbornene-based composite anion exchange membrane in anion exchange membrane water electrolysis or anion exchange membrane fuel cells.
[0031] The beneficial effects of this invention are:
[0032] (1) The present invention obtains the polynorbornene-based composite anion exchange membrane by introducing polysulfone resin or polybenzimidazole resin into ionic polynorbornene. The composite anion exchange membrane has significantly improved mechanical strength in the wet membrane state and can be used to assemble more stable water electrolysis devices, that is, the water electrolysis devices have significantly improved durability.
[0033] (2) By optimizing the ratio of the two polymer components, the present invention enables the prepared composite anion exchange membrane to maintain high ionic conductivity. Attached Figure Description
[0034] Figure 1 This is a comparison diagram of the tensile stress-strain curves of the anion exchange membrane samples in Examples 1-3 and Comparative Example 1.
[0035] Figure 2 This is a comparison chart of the water electrolysis performance of the anion exchange membrane samples in Example 1 and Comparative Example 1.
[0036] Figure 3 This is a comparison diagram of the tensile stress-strain curves of the anion exchange membrane samples in Examples 4-6 and Comparative Example 1.
[0037] Figure 4 This is a comparison chart of the water electrolysis performance of the anion exchange membrane samples in Example 4 and Comparative Example 1. Detailed Implementation
[0038] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.
[0039] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.
[0040] Example 1
[0041] First, 1 g of PSU (polysulfone) was dissolved in 100 mL of DMAc solution to prepare a homogeneous solution. Then, 10 g of ionic norbornene prepared according to Example 4 of Patent 2024112641293 was dissolved in 100 mL of DMAc solution to prepare a homogeneous solution. The two solutions were mixed evenly to form a mixed solution, and a homogeneous composite anion exchange membrane was prepared by solvent evaporation at 100 °C.
[0042] Example 2
[0043] First, 2 g of PSU (polysulfone) was dissolved in 100 mL of DMAc solution to prepare a homogeneous solution. Then, 10 g of ionic norbornene prepared according to Example 4 of Patent 2024112641293 was dissolved in 100 mL of DMAc solution to prepare a homogeneous solution. The two solutions were mixed evenly to form a mixed solution, and a homogeneous composite anion exchange membrane was prepared by solvent evaporation at 100 °C.
[0044] Example 3
[0045] First, 3 g of PSU (polysulfone) was dissolved in 100 mL of DMAc solution to prepare a homogeneous solution. Then, 10 g of ionic norbornene prepared according to Example 4 of Patent 2024112641293 was dissolved in 100 mL of DMAc solution to prepare a homogeneous solution. The two solutions were mixed evenly to form a mixed solution, and a homogeneous composite anion exchange membrane was prepared by solvent evaporation at 100 °C.
[0046] Example 4
[0047] First, 1 g of mPBI was dissolved in 100 mL of DMAc solution to prepare a homogeneous solution. Then, 10 g of ionic norbornene prepared according to Example 4 of Patent 2024112641293 was dissolved in 100 mL of DMAc solution to prepare a homogeneous solution. The two solutions were mixed evenly to form a mixed solution, and a homogeneous composite anion exchange membrane was prepared by solvent evaporation at 100 °C.
[0048] Example 5
[0049] First, 2 g of mPBI was dissolved in 100 mL of DMAc solution to prepare a homogeneous solution. Then, 10 g of ionic norbornene prepared according to Example 4 of Patent 2024112641293 was dissolved in 100 mL of DMAc solution to prepare a homogeneous solution. The two solutions were mixed evenly to form a mixed solution, and a homogeneous composite anion exchange membrane was prepared by solvent evaporation at 100 °C.
[0050] Example 6
[0051] First, 3 g of mPBI was dissolved in 100 mL of DMAc solution to prepare a homogeneous solution. Then, 10 g of ionic norbornene prepared according to Example 4 of Patent 2024112641293 was dissolved in 100 mL of DMAc solution to prepare a homogeneous solution. The two solutions were mixed evenly to form a mixed solution, and a homogeneous composite anion exchange membrane was prepared by solvent evaporation at 100 °C.
[0052] Comparative Example 1
[0053] According to Example 4 of Patent 2024112641293, 10 g of ionic norbornene was dissolved in 100 mL of DMAc solution to prepare a homogeneous solution, and a homogeneous anion exchange membrane was prepared by solvent evaporation at 100 °C.
[0054] Test Example 1
[0055] The mechanical properties of the anion exchange membranes in Examples 1-6 and Comparative Example 1 were determined. The test conditions were as follows: the anion exchange membrane samples were immersed in distilled water for 24 h, then dried with absorbent paper for 3 min before tensile testing. Tensile tests were performed five times at a tensile rate of 0.2 mm / min at room temperature. The average value of the middle three test results was calculated. The test results are shown in Table 1. The tensile strain curves are shown in Table 1. Figure 1 and Figure 3 .
[0056] Test Example 2
[0057] The conductivity of bicarbonate ions in Examples 1-6 and Comparative Example 1 was determined. The test conditions were as follows: the ion exchange membrane samples were immersed in NaHCO3 aqueous solution to replace bicarbonate ions, washed with deionized water and then the conductivity was tested. The resistance of the membrane was measured by electrochemical impedance spectroscopy, and the conductivity was calculated by formula (1). The test results are shown in Table 1.
[0058] Formula (1)
[0059] Test Example 3
[0060] The water electrolysis performance of the anion exchange membranes in Examples 1, 4, and Comparative Example 1 was determined. The test conditions were as described in Example 17 of patent 2025111848173. 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 sheets were cut to 2.0 cm × 2.0 cm, the effective area of the electrolyzer was 2.0 cm × 2.0 cm, and the concentration of the KOH aqueous solution was 1.0 M. The water electrolysis test was conducted for 110 hours. The test results are shown below. Figure 2and Figure 4 .
[0061] Table 1. Comparison of mechanical properties and ionic conductivity of anion exchange membranes in Examples 1-6 and Comparative Example 1
[0062]
[0063] The embodiments of the present invention have been described above by way of example. However, the scope of protection of the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A polynorbornene-based composite anion exchange membrane, characterized in that, The polynorbornene-based composite anion exchange membrane is used in anion exchange membrane water electrolysis or anion exchange membrane fuel cells. The composite anion exchange membrane comprises polysulfone resin and ionic polynorbornene, or the composite anion exchange membrane comprises polybenzimidazole resin and ionic polynorbornene. The mass ratio of the polysulfone resin to the ionic polynorbornene is 1:1~20; The mass ratio of the polybenzimidazole resin to the ionic polynorbornene is 1:1~20; The ionic polynorbornene comprises a polymer with a polynorbornene polymer backbone, the side chains of which contain quaternary ammonium cationic functional groups, wherein the quaternary ammonium cationic functional groups are selected from at least one of alkyl-trimethylamine cations and alkyl-N-methylpiperidine cations; The polynorbornene polymer backbone refers to the polymer backbone obtained by using norbornene as a monomer with a bicyclic [2.2.1]-2-heptene as the core structure; The preparation method of the ionic polynorbornene is as follows: First, a catalyst solution was prepared by dissolving 0.01 mmol Pd2(dba)3, 0.04 mmol PCy3, and 0.04 mmol LiFABA in 4 mL of toluene and stirring at room temperature for 1 h. A monomer solution was prepared by dissolving 2 mmol BrNB and 1 mmol VNB in 4 mL of toluene. Then, the catalyst solution was... The mixture was filtered through a filter membrane and added to the monomer solution. The mixture was stirred at room temperature. After the reaction was completed, the mixture was precipitated in methanol, sonicated, filtered, and a pale yellow solid was obtained. The solid was then dried under vacuum to prepare the addition polynorbornene copolymer. The above-mentioned addition polynorbornene copolymer was first stirred in NMP at 50°C for 5 hours. The polymer was dispersed but not dissolved. Then, an ethanol solution of trimethylamine was added and stirring was continued. As the reaction proceeded, the polymer gradually dissolved, and a clear and transparent solution was obtained. The reaction was carried out for 48 hours. After the reaction was completed, the mixture was cooled to room temperature, precipitated with diethyl ether, washed, and the solid product was collected by centrifugation to obtain ionic polynorbornene. The polysulfone resin refers to a type of polymer whose main molecular chain contains sulfone groups and is connected to aromatic rings on both sides. The number-average molecular weight of the polysulfone resin is 20,000 to 100,000; The number-average molecular weight of the ionic polynorbornene is 20,000 to 500,000. The number-average molecular weight of the polybenzimidazole resin ranges from 20,000 to 100,000.
2. The composite anion exchange membrane according to claim 1, characterized in that, The polysulfone resin is selected from at least one of the following: bisphenol A polysulfone, ether-bonded polyethersulfone, biphenyl-containing polyphenylsulfone, phenyl-containing polyphenylene sulfone, and polyarylsulfone containing multiple aromatic rings and heteroatoms.
3. The composite anion exchange membrane according to claim 1, characterized in that, The ion exchange capacity of the ionic polynorbornene is 0.5-3.0 mmol / g.
4. The composite anion exchange membrane according to claim 1, characterized in that, The polybenzimidazole resin refers to a class of polymers whose molecular backbone contains repeating benzimidazole units.
5. The composite anion exchange membrane according to claim 4, characterized in that, The polybenzimidazole resin is selected from at least one of poly[2,2'-(m-phenylene)-5,5'-dibenzimidazole], poly[2,5-(1,3-phenylene)benzimidazole], poly(2,2'-diphenyl ether-5,5'-dibenzimidazole), poly(2,2'-diphenyl sulfone-5,5'-dibenzimidazole), and poly(2,2'-hexafluoroisopropyl-5,5'-dibenzimidazole).
6. The method for preparing the composite anion exchange membrane according to any one of claims 1-5, characterized in that, The method includes: The composite anion exchange membrane is prepared by mixing a polysulfone resin solution or a polybenzimidazole resin solution with an ionic polynorbornene solution and forming the resulting mixed solution into a film.
7. The method according to claim 6, characterized in that, The polysulfone resin solution refers to polysulfone resin dissolved in a polar organic solvent, and the concentration of the polysulfone resin solution is 1 to 10 wt%.
8. The method according to claim 6, characterized in that, The polybenzimidazole resin solution refers to polybenzimidazole resin dissolved in a polar organic solvent, and the concentration of the polybenzimidazole resin solution is 1-10 wt%.
9. The method according to claim 6, characterized in that, The ionic polynorbornene solution refers to ionic polynorbornene dissolved 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-methylpyrrolidone.
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.