Dual wide-range high-acid-stable gel-like mixed-matrix pbi proton exchange membrane, its preparation method and application

Abstract

The application discloses a kind of double wide area-high acid retention gel state mixed matrix PBI proton exchange membrane and its preparation method and application, the gel state proton membrane is by flexible zirconium-glutamic acid (L-Glu-Zr (P)) or UiO-66 series metal organic framework, polybenzimidazole (PBI), phosphoric acid and water composition, its preparation method includes: with polyphosphoric acid as solvent, under the protection of inert gas, aromatic tetraamine monomer, dicarboxylic acid phenyl monomer high-temperature polycondensation forms PBI polymer solution, adds metal organic framework particle and disperses uniformly, mixed solution is scraped on substrate and experiences from solution to gel state membrane The phase transition process;Proton exchange membrane prepared in the application all shows excellent acid retention capacity, proton transport characteristics, fuel cell performance and stability under the service window of double wide area (temperature-20~240 DEG C, humidity 0~80%RH), has very good application prospect in fuel cell field.

Description

Technical Field

[0001] This invention relates to the field of proton exchange membranes that can be used in fuel cells, and particularly to a gel-state proton exchange membrane based on flexible zirconium-glutamic acid or UiO-66 series MOF-polybenzimidazole (PBI), its preparation method, and its application in dual-wideband fuel cells. Background Technology

[0002] Fuel cells are clean energy conversion devices that directly convert the chemical energy of fuel into electrical energy through electrochemical reactions, offering advantages such as high energy conversion efficiency, low pollution, and low carbon emissions. From the perspective of energy conservation and environmental protection, fuel cells are one of the most promising power generation technologies. Among them, proton exchange membrane fuel cells (PEMFCs) have advantages such as high output power density, fast start-up speed, and small size. In the mid-1990s, Wainright et al. pioneered the application of PBI membranes in HT-PEMFCs by doping them with phosphoric acid (PA) to improve proton conductivity. The proton conductivity of PA-PBI membranes is strongly dependent on the level of phosphoric acid doping (ADL) within the membrane. As the ADL increases, the proton conductivity increases significantly. However, PA-PBI proton exchange membranes suffer from phosphoric acid loss, leading to performance degradation, and their service window is limited to 120–200°C and a dry environment.

[0003] On the one hand, in high humidity environments, phosphoric acid inside the membrane is prone to leakage due to water vapor condensing in the battery and water generated from redox reactions, leading to difficulties in frequent starts or cold starts at low temperatures. On the other hand, in low-temperature environments, moisture inside the PEM may freeze, which not only blocks proton transport channels, causing a significant decrease in proton conductivity, but may also damage the microstructure of the membrane material due to freezing, thereby affecting its overall physical stability and service life.

[0004] Therefore, in the face of the challenges of proton exchange membranes (PEMs) in low-temperature and high-humidity environments, it is crucial to develop fuel cell PEMs that exhibit efficient and stable proton conduction performance in low-temperature environments and strong acid retention performance in high-humidity environments.

[0005] Based on this, this work combines the gel membrane preparation process with flexible zirconium-glutamic acid or UiO-66 series MOFs, revealing a gel proton exchange membrane based on its high-efficiency acid-retaining properties, its preparation method, and its applications. This proton exchange membrane exhibits excellent performance within a dual-wide service window (temperature -20 to 240℃, humidity 0 to 80% RH), showing great promise for application in the fuel cell field. Summary of the Invention

[0006] To overcome the shortcomings of existing proton exchange membranes, this invention provides a dual-wide-domain, high-acid-retaining gel-state hybrid matrix PBI proton exchange membrane, its preparation method, and its application.

[0007] The technical solution of the present invention is as follows:

[0008] A dual-wide-domain, high-acid-retaining gel-state hybrid matrix PBI proton exchange membrane is composed of polybenzimidazole, zirconium-based MOF, phosphoric acid, and water.

[0009] in,

[0010] The structural formula of polybenzimidazole is one or more of the following:

[0011]

[0012] In the formula, n = 40 to 60;

[0013] Polybenzimidazole is a homopolymer or random copolymer with a weight-average molecular weight between 50,000 and 130,000.

[0014] Zirconium-based MOFs are selected from flexible zirconium-glutamic acid MOFs (denoted as L-Glu-Zr(P)) or UiO-66 series MOFs.

[0015] Flexible zirconium-glutamate MOFs are synthesized through self-assembly using zirconium as the metal center and L-glutamate as the organic ligand. Specifically, the preparation method of flexible zirconium-glutamate MOFs is as follows:

[0016] Zirconium salt (preferably ZrCl4) was dissolved in water, and then L-glutamic acid was added under continuous stirring. The reaction mixture was transferred to a reaction vessel and reacted at 150°C for 2 hours. After cooling to room temperature, the mixture was centrifuged, washed, dried, and ground to obtain a flexible zirconium-glutamic acid MOF (L-Glu-Zr(P), white powder).

[0017] The UiO-66 series MOFs are prepared via a solvothermal reaction using zirconium as the metal center and dicarboxylic acid phenyl compounds as organic ligands. Specifically, the preparation method for the UiO-66 series MOFs is as follows:

[0018] Zirconium salt and dicarboxylic acid phenyl compound were dissolved in DMF, and organic acid was added as a regulator. The reaction mixture was then transferred to a reaction vessel and subjected to a solvothermal reaction at 120–200 °C for 24–48 h. After cooling to room temperature, the mixture was centrifuged, washed, dried, and ground to obtain UiO-66 series MOF (powder).

[0019] Zirconium salts are selected from one or both of zirconium tetrachloride (ZrCl4) and zirconium dichloride (ZrOCl2);

[0020] The dicarboxylic acid phenyl compound is selected from one or both of terephthalic acid and 2-aminoterephthalic acid.

[0021] The organic acid is selected from acetic acid, formic acid, or benzoic acid;

[0022] The prepared UiO-66 series MOFs are octahedral in shape with pore sizes of 0.6–1.4 nm and particle sizes of 100–1000 nm.

[0023] The preparation method of the dual-wide-range-high acid-retaining gel-state hybrid matrix PBI proton exchange membrane of the present invention includes: carrying out a polymerization reaction with polyphosphoric acid as solvent, adding flexible zirconium-glutamic acid (L-Glu-Zr(P)) or UiO-66 series MOF, and observing the phase transition from solution to gel-state matrix membrane after the process of scraping and hydration of polyphosphoric acid to phosphoric acid.

[0024] The prepared membrane structure is already rich in phosphoric acid, which is derived from the hydration of polyphosphoric acid in the polymer solution, enabling proton transfer without additional doping. The prepared membrane material has an acid doping level of 20–80 mol PA / PRU and a thickness of 200–1000 μm. 2 It has a specific surface area of ​​ / g, a porosity of 92.5%, and a pore size of 0.3–100 nm.

[0025] Specifically, the preparation method of the dual-wide-domain-high acid-retaining gel-state hybrid matrix PBI proton exchange membrane of the present invention is as follows:

[0026] (1) Using polyphosphoric acid as solvent and polycondensation agent, aromatic tetraamine monomer and dicarboxylic acid phenyl compound monomer undergo polycondensation reaction under an inert gas atmosphere to obtain polybenzimidazole polymer solution;

[0027] The aromatic tetraamine monomer is selected from one or more of 3,3'-diaminobenzidine and 1,2,4,5-tetraaminobenzene;

[0028] The dicarboxylic acid phenyl compound monomer is selected from one or more of terephthalic acid, isophthalic acid, 2,5-dihydroxyterephthalic acid, and 4,4'-dicarboxylic diphenyl ether;

[0029] The preferred molar ratio of aromatic tetraamine monomer to dicarboxylic acid phenyl compound monomer is 1:1;

[0030] The preferred total mass fraction of monomers in the polyphosphoric acid solvent is 1-15%;

[0031] The polycondensation reaction is carried out at a temperature of 170–200°C until the polymer solution reaches a suitable viscosity, and the reaction time is 20–72 h.

[0032] (2) Add zirconium-based MOF to the polybenzimidazole polymer solution obtained in step (1), stir and mix to disperse it evenly, and obtain a mixed matrix polymer solution;

[0033] The preferred mixing time is 3–15 hours;

[0034] Based on the total mass of polybenzimidazole and zirconium-based MOF, the preferred mass fraction of zirconium-based MOF is 1-50%;

[0035] (3) The mixed matrix polymer solution obtained in step (2) is coated on a glass substrate, and the solution-gel phase conversion is completed through the process of polyphosphoric acid hydration to synthesize phosphoric acid, thus obtaining the double wide-domain-high acid-retaining gel state mixed matrix PBI proton exchange membrane.

[0036] The thickness of the coated film is between 20 and 1000 μm;

[0037] The phase transformation temperature is 0–80℃, the humidity is 40–100%, and the phase transformation time is 10–30 h.

[0038] The dual-wide-domain, high-acid-retaining gel-state hybrid matrix PBI proton exchange membrane described in this invention can be used in fuel cells.

[0039] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0040] (1) The preparation process of this invention is mild, simple and feasible, low in cost, and the structure and morphology of the material are easy to control, with good dispersibility and uniformity, and easy to scale up;

[0041] (2) The proton exchange membrane prepared by the present invention not only has an ultra-high acid doping level and excellent proton conductivity, but also has excellent acid retention capacity in various temperature and humidity environments, avoiding the problems of low proton conductivity and severe acid loss of conventional membrane materials. The conductivity at -20℃ / no humidification is 0.0148 S / cm, the conductivity at 240℃ / 0%RH is 0.3422 S / cm, the acid retention rate at 40℃ / 80%RH (after 80 hours) is 68.43%, the acid retention rate at 80℃ / 40%RH (after 60 hours) is 81.8%, and the acid retention rate at 160℃ / 0%RH (after 60 hours) is 83.82%.

[0042] (3) The proton exchange membrane prepared by the present invention exhibits operational flexibility and realizes the low temperature and high humidity service range of hydrogen fuel cells (temperature -20 to 240°C, humidity 0 to 80%RH).

[0043] (4) This invention broadens the types and application scope of membrane materials used in fuel cell technology. Attached Figure Description

[0044] Figure 1 : Proton conduction performance diagrams of some embodiments and comparative examples.

[0045] Figure 2 : Proton conduction performance diagrams of some embodiments and comparative examples.

[0046] Figure 3 : Proton conduction stability performance diagrams (40℃-80%RH) of some embodiments and comparative examples.

[0047] Figure 4 Acid retention capacity performance graphs of some examples and comparative examples (40℃-80%RH).

[0048] Figure 5 : Proton conduction stability performance graphs of some embodiments and comparative examples (80℃-40%RH).

[0049] Figure 6 Acid retention capacity performance graphs of some examples and comparative examples (80℃-40%RH).

[0050] Figure 7 : Proton conduction stability performance graphs of some embodiments and comparative examples (160℃-0%RH).

[0051] Figure 8 Acid retention capacity performance graphs of some examples and comparative examples (160℃-0%RH).

[0052] Figure 9 Comparative Example 2: Fuel cell performance diagram (hydrogen / oxygen, no back pressure, no additional humidification).

[0053] Figure 10 Example 3: Fuel cell performance diagram (hydrogen / oxygen, no back pressure, no additional humidification).

[0054] Figure 11 Example 3: Fuel Cell Stability Chart (160℃ @ 0.2A / cm) 2 Hydrogen / oxygen, no back pressure, no additional humidification).

[0055] Figure 12 Cross-sectional morphology diagram of Example 3 (dephosphoric acid and freeze-dried).

[0056] Figure 13 Surface morphology diagram of Example 4 (dephosphoric acid and freeze-dried).

[0057] Figure 14 Cross-sectional morphology diagram of Example 5 (dephosphoric acid and freeze-dried).

[0058] Figure 15 XRD patterns of UiO-66-NH2 and UiO-66 prepared in this invention.

[0059] Figure 16 The curves showing the proton conductivity of the hybrid matrix proton membrane in the comparative example and some embodiments of this invention as a function of temperature (20-220°C).

[0060] Figure 17 The curves showing the change in proton conductivity with temperature (-20 to 20°C) in the comparative examples and some embodiments of this invention. Detailed Implementation

[0061] To facilitate understanding of the present invention, it will be described more fully in conjunction with the following examples. However, the present invention can be implemented in many different forms, and its scope of protection is not limited to the embodiments described herein. Furthermore, for those skilled in the art, various modifications or improvements to the material composition and dosage in these embodiments, without departing from the spirit and scope of the present invention, are all within the scope of protection claimed by the present invention.

[0062] In the following embodiments,

[0063] The preparation method of L-Glu-Zr(P) is as follows:

[0064] Weigh out 0.200 g (0.001 mol) of ZrCl4 and dissolve it in 10 mL of room temperature water. Then, under continuous stirring, slowly add L-glutamic acid (L-Glu, 0.13 g, 0.001 mol) to the above solution. Transfer the mixture to a 150 mL reaction vessel and react in an oven at 150 °C for 2 h. After cooling, wash the product by multiple centrifugations with ethanol. Finally, dry and grind the product obtained by centrifugation to obtain white L-Glu-Zr(P) powder.

[0065] The preparation method of UiO-66-NH2 is as follows:

[0066] Weigh out ZrCl4 (0.400 g, 0.004 mol) and 2-aminoterephthalic acid (BDC-NH2, 0.31 g, 0.002 mol), add 20 mL DMF and 0.6 mL acetic acid as a conditioner, and mix well. Transfer the mixture to a 150 mL reactor and place it in a 120 °C oven for 24 h. After cooling, wash and centrifuge repeatedly with DMF and ethanol. Finally, dry and grind the centrifuged product to obtain a pale yellow UiO-66-NH2 powder.

[0067] The preparation method of UiO-66 is as follows:

[0068] Weigh out ZrCl4 (0.190 g, 0.002 mol) and terephthalic acid (BDC, 0.133 g, 0.001 mol), add 81.7 mL DMF and 2.29 mL acetic acid as a conditioner, and mix well. Transfer the mixture to a 150 mL reactor and place it in a 120 °C oven for 24 h. After cooling, wash and centrifuge repeatedly with DMF and ethanol. Finally, dry and grind the centrifuged product to obtain white UiO-66 powder.

[0069] Comparative Example 1:

[0070] A conventional PA / PBI membrane was prepared by immersing a commercially available PBI membrane provided by PBI Performance in an 85 wt% phosphoric acid solution for 168 hours to complete acid doping.

[0071] The conventional PA / PBI membrane obtained in Comparative Example 1 was analyzed and tested:

[0072] Experimental results: Phosphoric acid doping level: 7.73 mol PA / PRU.

[0073] Proton conductivity (without additional humidification): 25℃ conductivity: 0.015S / cm, 80℃ conductivity: 0.051S / cm, 200℃ conductivity: 0.096S / cm, 240℃ conductivity: 0.070S / cm.

[0074] Comparative Example 2:

[0075] (1) Weigh 2.0692 g of 3,3'-diaminobenzidine and 1.6043 g of terephthalic acid, respectively, and pour them into a three-necked reactor. Then add 180 g of solvent and polyphosphate condensation agent to the reactor. React under a nitrogen atmosphere and use an oil bath heating method to gradually increase the temperature to 190°C and react for 25 hours.

[0076] (2) Pour the polymer solution onto the glass substrate and use a scraper to scrape the film, controlling the film thickness to be 250 μm.

[0077] (3) Place the glass plate and membrane in an environment with a temperature of room temperature and a humidity of 60%RH for 12 hours to allow the membrane precursor phase to transform. The proton exchange membrane of Comparative Example 2 is then obtained.

[0078] Comparative Example 2 has a proton exchange membrane structure of para-PBI, and does not contain L-Glu-Zr(P).

[0079] The proton exchange membrane of the control group obtained in Comparative Example 2 was analyzed and tested:

[0080] The proton exchange membrane of the control group obtained in this example was subjected to membrane performance testing. The experimental results are as follows: conductivity at -20℃ / no humidification: 0.0054 S / cm, conductivity at 240℃ / 0%RH: 0.2624 S / cm, conductivity at 40℃ / 80%RH (after 80 hours): 0.1131 S / cm, conductivity at 80℃ / 40%RH (after 60 hours): 0.0788 S / cm, and conductivity at 160℃ / 0%RH (after 60 hours): 0.1604 S / cm.

[0081] The acid retention capacity of the proton exchange membrane obtained in this example was tested. The results were as follows: acid retention rate at 40℃ / 80%RH (after 80 hours): 47.22%; acid retention rate at 80℃ / 40%RH (after 60 hours): 61.3%; acid retention rate at 160℃ / 0%RH (after 60 hours): 57.41%.

[0082] The proton exchange membrane obtained in this example was used to test the fuel cell performance. The experimental results showed that at 30℃, the peak power density was 146 mW / cm³. 2 At 200℃, the peak power density is 755 mW / cm³. 2 .

[0083] Comparative Example 3:

[0084] (1) Weigh out 5.3000 g of 3,3'-diaminobenzidine, 0.5137 g of terephthalic acid, and 3.5956 g of isophthalic acid, respectively, and pour them into a three-necked reactor. Then add 100 g of solvent and polyphosphate condensation agent to the reactor. React under a nitrogen atmosphere and use an oil bath heating method with a programmed gradient temperature increase to 190℃ for 20 hours.

[0085] (2) Pour the polymer solution onto the glass substrate and use a scraper to scrape the film, controlling the film thickness to be 250 μm.

[0086] (3) Place the glass plate and membrane in an environment with a temperature of room temperature and a humidity of 60%RH for 12 hours to allow the membrane precursor phase to transform. The proton exchange membrane of Comparative Example 3 is then obtained.

[0087] Comparative Example 3 has a proton exchange membrane structure of mrp-PBI, and does not contain L-Glu-Zr(P).

[0088] The proton exchange membrane of the control group obtained in Comparative Example 3 was analyzed and tested:

[0089] The proton exchange membrane of the control group obtained in this example was tested for membrane performance. The experimental results showed that the conductivity at 240℃ was 0.1566 S / cm.

[0090] Example 1:

[0091] (1) Weigh 2.0692 g of 3,3'-diaminobenzidine and 1.6043 g of terephthalic acid, respectively, and pour them into a three-necked reactor. Then add 180 g of solvent and polyphosphate condensation agent to the reactor. The reaction is carried out under a nitrogen atmosphere and an oil bath heating method is used to gradually increase the temperature to 190°C and react for 35 hours.

[0092] (2) Add 0.1933g of L-Glu-Zr(P) to the polymer solution and stir for 8h, wherein the mass concentration of L-Glu-Zr(P) is 5% (relative to the total mass of polybenzimidazole and particles).

[0093] (3) Pour the polymer solution onto the glass substrate and use a film scraper to scrape the film, controlling the film thickness to be 200 μm.

[0094] (4) Place the membrane in a room temperature, 70% RH environment for 12 hours to allow the membrane precursor to undergo phase inversion, thereby obtaining the gel-state proton exchange membrane para-PBI-(L-Glu-Zr(P))-5% based on flexible amino acid MOF-polybenzimidazole.

[0095] The mixed matrix gel-type high-temperature proton exchange membrane para-PBI-(L-Glu-Zr(P))-5% obtained in Example 1 was analyzed and tested:

[0096] The hybrid matrix gel-type high-temperature proton exchange membrane obtained in this example was subjected to membrane performance testing. The experimental results are as follows: conductivity at -20℃ / no humidification: 0.0063 S / cm; conductivity at 240℃ / 0%RH: 0.2661 S / cm; conductivity at 40℃ / 80%RH (after 80 hours): 0.2341 S / cm; conductivity at 80℃ / 40%RH (after 60 hours): 0.12224 S / cm; conductivity at 160℃ / 0%RH (after 60 hours): 0.1707 S / cm.

[0097] The acid retention capacity of the hybrid matrix gel-type high-temperature proton exchange membrane obtained in this example was tested. The experimental results were as follows: acid retention rate at 40℃ / 80%RH (after 80 hours): 52.11%; acid retention rate at 80℃ / 40%RH (after 60 hours): 69.3%; and acid retention rate at 160℃ / 0%RH (after 60 hours): 64.04%.

[0098] Example 2:

[0099] (1) Weigh 2.0692 g of 3,3'-diaminobenzidine and 1.6043 g of terephthalic acid, respectively, and pour them into a three-necked reactor. Then add 180 g of solvent and polyphosphate condensation agent to the reactor. The reaction is carried out under a nitrogen atmosphere and an oil bath heating method is used to gradually increase the temperature to 190°C and react for 35 hours.

[0100] (2) Add 0.4082 g of L-Glu-Zr(P) to the polymer solution and stir for 8 h, wherein the mass concentration of L-Glu-Zr(P) is 10% (relative to the total mass of polybenzimidazole and particles).

[0101] (3) Pour the polymer solution onto the glass substrate and use a scraper to scrape the film, controlling the film thickness to be 250 μm.

[0102] (4) Place the membrane in a room temperature, 60% RH environment for 12 hours to allow the membrane precursor to undergo phase inversion, thereby obtaining the gel-state proton exchange membrane para-PBI-(L-Glu-Zr(P))-10% based on flexible amino acid MOF-polybenzimidazole.

[0103] The mixed matrix gel-type high-temperature proton exchange membrane para-PBI-(L-Glu-Zr(P))-10% obtained in Example 2 was analyzed and tested:

[0104] The hybrid matrix gel-type high-temperature proton exchange membrane obtained in this example was subjected to membrane performance testing. The experimental results are as follows: conductivity at -20℃ / no humidification: 0.0099 S / cm; conductivity at 240℃ / 0%RH: 0.2745 S / cm; conductivity at 40℃ / 80%RH (after 80 hours): 0.2036 S / cm; conductivity at 80℃ / 40%RH (after 60 hours): 0.17157 S / cm; conductivity at 160℃ / 0%RH (after 60 hours): 0.1897 S / cm.

[0105] The acid retention capacity of the hybrid matrix gel-type high-temperature proton exchange membrane obtained in this example was tested. The experimental results were as follows: acid retention rate at 40℃ / 80%RH (after 80 hours): 57.37%; acid retention rate at 80℃ / 40%RH (after 60 hours): 82.00%; and acid retention rate at 160℃ / 0%RH (after 60 hours): 67.14%.

[0106] Example 3:

[0107] (1) Weigh 2.0692 g of 3,3'-diaminobenzidine and 1.6043 g of terephthalic acid, respectively, and pour them into a three-necked reactor. Then add 180 g of solvent and polyphosphate condensation agent to the reactor. The reaction is carried out under a nitrogen atmosphere and an oil bath heating method is used to gradually increase the temperature to 190°C and react for 35 hours.

[0108] (2) Add 0.6482 g of L-Glu-Zr(P) to the polymer solution and stir for 8 h, wherein the mass concentration of L-Glu-Zr(P) is 15% (relative to the total mass of polybenzimidazole and particles).

[0109] (3) Pour the polymer solution onto the glass substrate and use a scraper to scrape the film, controlling the film thickness to be 250 μm.

[0110] (4) Place the membrane in a room temperature, 60% RH environment for 12 hours to allow the membrane precursor to undergo phase inversion, thereby obtaining the gel-state proton exchange membrane para-PBI-(L-Glu-Zr(P))-15 based on flexible amino acid MOF-polybenzimidazole.

[0111] The mixed matrix gel-type high-temperature proton exchange membrane para-PBI-(L-Glu-Zr(P))-15% obtained in Example 3 was analyzed and tested:

[0112] The hybrid matrix gel-type high-temperature proton exchange membrane obtained in this example was subjected to membrane performance testing. The experimental results are as follows: conductivity at -20℃ / no humidification: 0.0148 S / cm; conductivity at 240℃ / 0%RH: 0.3422 S / cm; conductivity at 40℃ / 80%RH (after 80 hours): 0.1536 S / cm; conductivity at 80℃ / 40%RH (after 60 hours): 0.1872 S / cm; conductivity at 160℃ / 0%RH (after 60 hours): 0.2616 S / cm.

[0113] The acid retention capacity of the hybrid matrix gel-type high-temperature proton exchange membrane obtained in this example was tested. The experimental results were as follows: acid retention rate at 40℃ / 80%RH (after 80 hours): 68.43%; acid retention rate at 80℃ / 40%RH (after 60 hours): 81.8%; and acid retention rate at 160℃ / 0%RH (after 60 hours): 83.82%.

[0114] The hybrid matrix gel-type high-temperature proton exchange membrane obtained in this example was used to test the performance and stability of a fuel cell. The experimental results showed that at 30℃, the peak power density was 354 mW / cm³. 2 At 200℃, the peak power density is 1160 mW / cm³. 2 160℃@0.2A / cm 2 The voltage decay rate was 0.29 μV / h (for a total of 575 hours of testing).

[0115] Example 4:

[0116] (1) Weigh 2.0692 g of 3,3'-diaminobenzidine and 1.6043 g of terephthalic acid, respectively, and pour them into a three-necked reactor. Then add 180 g of solvent and polyphosphate condensation agent to the reactor. The reaction is carried out under a nitrogen atmosphere using an oil bath heating method, with the temperature gradually increased to 190 °C and reacted for 35 hours.

[0117] (2) Add 0.9184 g of L-Glu-Zr(P) to the polymer solution and mix for 8 h, wherein the mass concentration of L-Glu-Zr(P) is 20% (relative to the total mass of polybenzimidazole and particles).

[0118] (3) Pour the polymer solution onto the glass substrate and use a scraper to scrape the film, controlling the film thickness to be 250 μm.

[0119] (4) Place the membrane in a room temperature, 70% RH environment for 12 hours to allow the membrane precursor to undergo phase inversion, thereby obtaining the gel-state proton exchange membrane para-PBI-(L-Glu-Zr(P))-20% based on flexible amino acid MOF-polybenzimidazole.

[0120] The mixed matrix gel-type high-temperature proton exchange membrane para-PBI-(L-Glu-Zr(P))-20% obtained in Example 4 was analyzed and tested:

[0121] The hybrid matrix gel-type high-temperature proton exchange membrane obtained in this example was subjected to membrane performance testing. The experimental results are as follows: conductivity at -20℃ / no humidification: 0.0106 S / cm; conductivity at 240℃ / 0%RH: 0.3061 S / cm; conductivity at 40℃ / 80%RH (after 80 hours): 0.19173 S / cm; conductivity at 80℃ / 40%RH (after 60 hours): 0.16223 S / cm; conductivity at 160℃ / 0%RH (after 60 hours): 0.2086 S / cm.

[0122] The acid retention capacity of the hybrid matrix gel-type high-temperature proton exchange membrane obtained in this example was tested. The experimental results were as follows: acid retention rate at 40℃ / 80%RH (after 80 hours): 60.99%; acid retention rate at 80℃ / 40%RH (after 60 hours): 77.6%; and acid retention rate at 160℃ / 0%RH (after 60 hours): 73.15%.

[0123] Example 5:

[0124] (1) Weigh 2.0692 g of 3,3'-diaminobenzidine and 1.6043 g of terephthalic acid, respectively, and pour them into a three-necked reactor. Then add 180 g of solvent and polyphosphate condensation agent to the reactor. The reaction is carried out under a nitrogen atmosphere and an oil bath heating method is used to gradually increase the temperature to 190°C and react for 35 hours.

[0125] (2) Add 1.5744 g of L-Glu-Zr(P) to the polymer solution and stir for 8 h, wherein the mass concentration of L-Glu-Zr(P) is 30% (relative to the total mass of polybenzimidazole and particles).

[0126] (3) Pour the polymer solution onto the glass substrate and use a scraper to scrape the film, controlling the film thickness to be 250 μm.

[0127] (4) Place the membrane in a room temperature, 60% RH environment for 12 hours to allow the membrane precursor to undergo phase inversion, thereby obtaining a gel-state proton exchange membrane para-PBI-(L-Glu-Zr(P))-30% based on flexible amino acid MOF-polybenzimidazole.

[0128] The mixed matrix gel-type high-temperature proton exchange membrane para-PBI-(L-Glu-Zr(P))-30% obtained in Example 5 was analyzed and tested:

[0129] The hybrid matrix gel-type high-temperature proton exchange membrane obtained in this example was subjected to membrane performance testing. The experimental results are as follows: conductivity at -20℃ / no humidification: 0.0075 S / cm; conductivity at 240℃ / 0%RH: 0.2363 S / cm; conductivity at 40℃ / 80%RH (after 80 hours): 0.1657 S / cm; conductivity at 80℃ / 40%RH (after 60 hours): 0.2296 S / cm; conductivity at 160℃ / 0%RH (after 60 hours): 0.15281 S / cm.

[0130] The acid retention capacity of the hybrid matrix gel-type high-temperature proton exchange membrane obtained in this example was tested. The experimental results were as follows: acid retention rate at 40℃ / 80%RH (after 80 hours): 62.90%; acid retention rate at 80℃ / 40%RH (after 60 hours): 59.5%; and acid retention rate at 160℃ / 0%RH (after 60 hours): 60.44%.

[0131] Example 6:

[0132] (1) Weigh out 4.2399 g of 3,3'-diaminobenzidine, 0.4109 g of terephthalic acid, and 2.8764 g of isophthalic acid, respectively, and pour them into a three-necked reactor. Then add 80 g of solvent and polyphosphate condensation agent to the reactor. React under a nitrogen atmosphere and use an oil bath heating method to gradually increase the temperature to 190℃ and react for 20 hours.

[0133] (2) Add 0.5666g of L-Glu-Zr(P) to the polymer solution and stir for 8h, wherein the mass concentration of L-Glu-Zr(P) is 7% (relative to the total mass of polybenzimidazole and particles).

[0134] (3) Pour the polymer solution onto the glass substrate and use a scraper to scrape the film, controlling the film thickness to be 250 μm.

[0135] (4) Place the membrane in a room temperature, 60% RH environment for 12 hours to allow the membrane precursor to undergo phase inversion, thereby obtaining the gel-state proton exchange membrane mrp-PBI-(L-Glu-Zr(P))-7 based on flexible amino acid MOF-polybenzimidazole.

[0136] The mixed matrix gel-type high-temperature proton exchange membrane mrp-PBI-(L-Glu-Zr(P))-7% obtained in Example 6 was analyzed and tested:

[0137] The mixed matrix gel-type high-temperature proton exchange membrane obtained in this example was tested for membrane performance. The experimental results showed that the conductivity at 240℃ was 0.2526 S / cm.

[0138] Example 7:

[0139] (1) Weigh 4.2399 g of 3,3'-diaminobenzidine, 0.4109 g of terephthalic acid, and 2.8764 g of isophthalic acid into a three-necked reactor, and then add 80 g of solvent and polyphosphate condensation agent to the reactor. The reaction is carried out under a nitrogen atmosphere and heated in an oil bath with a programmed gradient to 190 °C for 20 hours.

[0140] (2) Add 1.3283g of L-Glu-Zr(P) to the polymer solution and stir for 8h, wherein the mass concentration of L-Glu-Zr(P) is 15% (relative to the total mass of polybenzimidazole and particles).

[0141] (3) Pour the polymer solution onto the glass substrate and use a scraper to scrape the film, controlling the film thickness to be 250 μm.

[0142] (4) Place the membrane in a room temperature, 60% RH environment for 12 hours to allow the membrane precursor to undergo phase inversion, thereby obtaining the gel-state proton exchange membrane mrp-PBI-(L-Glu-Zr(P))-15 based on flexible amino acid MOF-polybenzimidazole.

[0143] The mixed matrix gel-type high-temperature proton exchange membrane mrp-PBI-(L-Glu-Zr(P))-15% obtained in Example 7 was analyzed and tested:

[0144] The hybrid matrix gel-type high-temperature proton exchange membrane obtained in this example was tested for membrane performance. The experimental results showed that the conductivity at 240℃ was 0.2270 S / cm.

[0145] Example 8:

[0146] (1) Weigh 4.2399 g of 3,3'-diaminobenzidine, 0.4109 g of terephthalic acid, and 2.8764 g of isophthalic acid into a three-necked reactor, and then add 80 g of solvent and polyphosphate condensation agent to the reactor. The reaction is carried out under a nitrogen atmosphere and heated in an oil bath with a programmed gradient to 190 °C for 20 hours.

[0147] (2) Add 3.2259g of L-Glu-Zr(P) to the polymer solution and stir for 8h, wherein the mass concentration of L-Glu-Zr(P) is 30% (relative to the total mass of polybenzimidazole and particles).

[0148] (3) Pour the polymer solution onto the glass substrate and use a scraper to scrape the film, controlling the film thickness to be 250 μm.

[0149] (4) Place the membrane in a room temperature, 60% RH environment for 12 hours to allow the membrane precursor to undergo phase inversion, thereby obtaining the gel-state proton exchange membrane mrp-PBI-(L-Glu-Zr(P))-30 based on flexible amino acid MOF-polybenzimidazole.

[0150] The mixed matrix gel-type high-temperature proton exchange membrane mrp-PBI-(L-Glu-Zr(P))-30% obtained in Example 8 was analyzed and tested:

[0151] The hybrid matrix gel-type high-temperature proton exchange membrane obtained in this example was tested for membrane performance. The experimental results showed that the conductivity at 240℃ was 0.1787 S / cm.

[0152] Example 9

[0153] (1) Weigh 3.1358 g of 3,3'-diaminobenzidine and 2.4312 g of terephthalic acid, respectively, and pour them into a three-necked reactor. Then add 180 g of solvent and polyphosphate condensation agent to the reactor. React under a nitrogen atmosphere and use an oil bath heating method to react at 190°C for 25 h.

[0154] (2) Add 0.4082g (10wt%) UiO-66-NH2 powder in small amounts several times at 180℃, and continue heating and stirring for 4h until the mixture is uniform to obtain the casting solution.

[0155] (3) The casting solution obtained in (2) was directly cast onto a clean glass plate in an air environment, and a coating tool was used to scrape the film to control the film thickness to 250 μm. The film was placed in a room temperature and 60% RH environment for sol-gel phase inversion, and after standing for 24 h, the proton membrane of Example 9 was obtained.

[0156] The gel-state hybrid matrix proton exchange membrane obtained in this embodiment was tested for membrane performance. The experimental results are as follows: Proton conductivity at 160℃: 0.319 S / cm. With an acid doping level of 61.21 mol PA / PRU, after maintaining the membrane at 80℃ and 40% RH for 50 h, the acid doping level decreased to 13.16 mol PA / PRU, with a retention rate of 51.97%. After maintaining the membrane at 160℃ and 0% RH for 60 h, the acid doping level decreased to 16.22 mol PA / PRU, with a retention rate of 62.19%. The proton conductivity retained 85.55% after maintaining the membrane at 80℃ and 40% RH for 60 h, and 85.19% after maintaining the membrane at 160℃ and 0% RH for 70 h.

[0157] Example 10

[0158] (1) Weigh 3.1358 g of 3,3'-diaminobenzidine and 2.4312 g of terephthalic acid, respectively, and pour them into a three-necked reactor. Then add 180 g of solvent and polyphosphate condensation agent to the reactor. React under a nitrogen atmosphere and use an oil bath heating method to react at 190°C for 27 h.

[0159] (2) Add 0.6483g (15wt%) UiO-66-NH2 powder in small amounts several times at 180℃, and continue heating and stirring for 4h until the mixture is uniform to obtain the casting solution.

[0160] (3) The casting solution obtained in (2) was directly cast onto a clean glass plate in an air environment, and a coating tool was used to scrape the film to control the film thickness to 250 μm. The film was placed in a room temperature and 60% RH environment for sol-gel phase inversion, and after standing for 24 h, the proton membrane of Example 10 was obtained.

[0161] The metal-organic framework material UiO-66-NH2 in this embodiment is prepared as follows: A certain amount of ZrCl4 and 2-aminoterephthalic acid (BDC-NH2) are weighed at a molar ratio of 1:1, and 20 mL of DMF and 0.6 mL of acetic acid regulator are added and mixed well. The mixed solution is transferred to a 150 mL reaction vessel and placed in an oven at 120 °C for 24 h. After cooling, the mixture is washed and centrifuged repeatedly with DMF and ethanol. Finally, the product obtained by centrifugation is dried and ground to obtain a light yellow UiO-66-NH2 powder.

[0162] The gel-state hybrid matrix proton exchange membrane obtained in this embodiment was tested for membrane performance. The experimental results showed that the proton conductivity at 160℃ was 0.250 S / cm. With an acid doping level of 53.26 mol PA / PRU, after maintaining the membrane at 80℃ and 40% RH for 50 h, the acid doping level decreased to 20.47 mol PA / PRU, with a retention rate of 59.73%. After maintaining the membrane at 160℃ and 0% RH for 60 h, the acid doping level decreased to 27.83 mol PA / PRU, with a retention rate of 73.14%. The proton conductivity retained 88.34% after maintaining the membrane at 80℃ and 40% RH for 60 h, and 87.54% after maintaining the membrane at 160℃ and 0% RH for 70 h.

[0163] Example 11

[0164] (1) Weigh 3.1358 g of 3,3'-diaminobenzidine and 2.4312 g of terephthalic acid, respectively, and pour them into a three-necked reactor. Then add 180 g of solvent and polyphosphate condensation agent to the reactor. React under a nitrogen atmosphere and use an oil bath heating method to react at 190°C for 28 h.

[0165] (2) Add 0.9184g (20wt%) UiO-66-NH2 powder in small amounts several times at 180℃, and continue heating and stirring for 4h until the mixture is uniform to obtain the casting solution.

[0166] (3) The casting solution obtained in (2) was directly cast onto a clean glass plate in an air environment, and a coating tool was used to scrape the film to control the film thickness to 250 μm. The film was placed in a room temperature and 60% RH environment for sol-gel phase inversion, and after standing for 24 h, the proton membrane of Example 11 was obtained.

[0167] The metal-organic framework material UiO-66-NH2 in this embodiment is prepared as follows: A certain amount of ZrCl4 and 2-aminoterephthalic acid (BDC-NH2) are weighed at a molar ratio of 1:1, and 20 mL of DMF and 0.6 mL of acetic acid regulator are added and mixed well. The mixed solution is transferred to a 150 mL reaction vessel and placed in an oven at 120 °C for 24 h. After cooling, the mixture is washed and centrifuged repeatedly with DMF and ethanol. Finally, the product obtained by centrifugation is dried and ground to obtain a light yellow UiO-66-NH2 powder.

[0168] The gel-state hybrid matrix proton exchange membrane obtained in this embodiment was tested for membrane performance. The experimental results showed that the proton conductivity at 160℃ was 0.231 S / cm. With an acid doping level of 46.64 mol PA / PRU, after maintaining the membrane at 80℃ and 40% RH for 50 h, the acid doping level decreased to 21.28 mol PA / PRU, with a retention rate of 59.79%. After maintaining the membrane at 160℃ and 0% RH for 60 h, the acid doping level decreased to 28.85 mol PA / PRU, with a retention rate of 71.16%. The proton conductivity retained 80.45% after maintaining the membrane at 80℃ and 40% RH for 60 h, and 81.22% after maintaining the membrane at 160℃ and 0% RH for 70 h.

[0169] Example 12

[0170] (1) Weigh 3.1358 g of 3,3'-diaminobenzidine and 2.4312 g of terephthalic acid, respectively, and pour them into a three-necked reactor. Then add 180 g of solvent and polyphosphate condensation agent to the reactor. React under a nitrogen atmosphere and use an oil bath heating method to react at 190°C for 28 h.

[0171] (2) Add 0.4082g (10wt%) of UiO-66 powder in small amounts several times at 180℃, and continue heating and stirring for 4h until the mixture is uniform to obtain the casting solution.

[0172] (3) The casting solution obtained in (2) was directly cast onto a clean glass plate in an air environment, and a coating tool was used to scrape the film to control the film thickness to 250 μm. The film was placed in a room temperature and 60% RH environment for sol-gel phase inversion, and after standing for 24 h, the proton membrane of Example 12 was obtained.

[0173] The gel-state hybrid matrix proton membrane obtained in this embodiment was subjected to membrane performance testing. The experimental results showed that the proton conductivity at 160℃ was 0.262 S / cm.

[0174] This work combines gel membrane preparation technology with flexible zirconium-glutamate (L-Glu-Zr(P)) or UiO-66 series MOFs to develop a highly efficient acid-retaining gel proton exchange membrane, along with its preparation method and applications. This proton exchange membrane exhibits excellent performance over a wide operating range (temperature -20 to 240℃, humidity 0 to 80% RH).

[0175] In fuel cells, the flexible L-Glu-Zr(P) can spontaneously absorb water molecules that easily lead to phosphoric acid loss due to the water vapor environment generated by condensation, thereby extending the service life of the proton exchange membrane. L-Glu-Zr(P) itself has extremely high proton conductivity, which significantly improves the proton conductivity of the L-Glu-Zr(P)-doped PBI proton exchange membrane, effectively alleviating the difficulties of cold start-up at low temperatures and the poor performance of fuel cells at high temperatures.

[0176] Furthermore, the UiO-66 series MOFs, with their excellent thermal and chemical stability, enable UiO-66-doped mixed matrix proton exchange membranes to maintain superior performance over a wide temperature range from -20°C to 220°C. The porous structure and basic functional groups of UiO-66 effectively limit the loss of phosphate, significantly improving acid retention under low temperature and high humidity conditions. Due to the effective retention of phosphate and the microporous mass transfer effect of UiO-66, this proton exchange membrane exhibits excellent proton conductivity at both high and low temperatures. The porous, layered structure inside the membrane increases the proton transport pathways, facilitating rapid proton migration within the membrane. This membrane not only maintains stable performance over a wide temperature range but also maintains high proton conductivity and excellent acid retention under varying water contents. Furthermore, through specific intermolecular interactions or structural design, the retention capacity of phosphate is further enhanced.

Claims

1. A dual-wide-range, high-acid-retaining gel-state hybrid matrix PBI proton exchange membrane, characterized in that, It is composed of polybenzimidazole, zirconium-based MOF, phosphoric acid, and water; in, The structural formula of polybenzimidazole is one or more of the following: In the formula, n = 40~60; Polybenzimidazole is a homopolymer or random copolymer with a weight-average molecular weight between 50,000 and 130,000. Zirconium-based MOFs are selected from flexible zirconium-glutamic acid MOFs or UiO-66 series MOFs; The preparation method of the dual-wide-domain, high-acid-retaining gel-state hybrid matrix PBI proton exchange membrane is as follows: (1) Using polyphosphoric acid as solvent and polycondensation agent, aromatic tetraamine monomer and dicarboxylic acid phenyl compound monomer undergo polycondensation reaction under an inert gas atmosphere to obtain polybenzimidazole polymer solution; The aromatic tetraamine monomer is selected from one or more of 3,3'-diaminobenzidine and 1,2,4,5-tetraaminobenzene; The dicarboxylic acid phenyl compound monomer is selected from one or more of terephthalic acid, isophthalic acid, 2,5-dihydroxyterephthalic acid, and 4,4'-dicarboxylic diphenyl ether; (2) Add zirconium-based MOF to the polybenzimidazole polymer solution obtained in step (1), stir and mix to disperse it evenly, and obtain a mixed matrix polymer solution; (3) The mixed matrix polymer solution obtained in step (2) is scraped onto a glass substrate, and the solution-gel phase conversion is completed through the process of polyphosphoric acid hydration to synthesize phosphoric acid, thus obtaining the double-wide-domain-high acid-retaining gel state mixed matrix PBI proton exchange membrane.

2. The dual-wide-range, high-acid-retaining gel-state hybrid matrix PBI proton exchange membrane as described in claim 1, characterized in that, Flexible zirconium-glutamic acid MOFs are synthesized by self-assembly using zirconium as the metal center and L-glutamic acid as the organic ligand; UiO-66 series MOFs are prepared by solvothermal reaction using zirconium as the metal center and dicarboxylic acid phenyl compounds as organic ligands.

3. The dual-wide-range, high-acid-retaining gel-state hybrid matrix PBI proton exchange membrane as described in claim 1, characterized in that, In step (1) of the preparation method, the molar ratio of aromatic tetraamine monomer to dicarboxylic acid phenyl compound monomer is 1:

1.

4. The dual-wide-range, high-acid-retaining gel-state hybrid matrix PBI proton exchange membrane as described in claim 1, characterized in that, In step (1) of the preparation method, the total mass fraction of monomers in the polyphosphoric acid solvent is 1-15%.

5. The dual-wide-range, high-acid-retaining gel-state hybrid matrix PBI proton exchange membrane as described in claim 1, characterized in that, In step (1) of the preparation method, the temperature of the polycondensation reaction is 170~200℃. o C, reaction time 20~72h.

6. The dual-wide-range, high-acid-retaining gel-state hybrid matrix PBI proton exchange membrane as described in claim 1, characterized in that, In step (2) of the preparation method, the mass fraction of zirconium-based MOF is 1-50% based on the total mass of polybenzimidazole and zirconium-based MOF.

7. The dual-wide-range, high-acid-retaining gel-state hybrid matrix PBI proton exchange membrane as described in claim 1, characterized in that, In step (3) of the preparation method, the thickness of the film is 20~1000μm.

8. The dual-wide-range, high-acid-retaining gel-state hybrid matrix PBI proton exchange membrane as described in claim 1, characterized in that, In step (3) of the preparation method, the phase transformation temperature is 0~80℃, the humidity is 40~100%, and the phase transformation time is 10~30h.

9. The application of the dual-wide-domain, high-acid-retaining gel-state hybrid matrix PBI proton exchange membrane as described in claim 1 in fuel cells.

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