Preparation method and application of high-temperature fuel cell proton exchange membrane

Abstract

The application provides a preparation method and application of a high-temperature fuel cell proton exchange membrane, and the preparation method comprises the following steps: immersing an N-COF-PBI membrane in a phosphoric acid solution; the raw material of the N-COF-PBI membrane is N-COF-PBI; the N-COF-PBI is obtained by mixing a reaction monomer of PBI with N-COF and then performing an in-situ covalent polycondensation reaction; the prepared high-temperature fuel cell proton exchange membrane can be applied to the preparation of a high-temperature fuel cell membrane electrode and a high-temperature fuel cell. The method is simple, the prepared high-temperature fuel cell proton exchange membrane has the characteristics of high phosphoric acid retention capacity, high tensile strength (120 MPa) and long service life, the highest electrical conductivity of the high-temperature fuel cell proton exchange membrane under the condition of 160 DEG C can reach 3.0 S / cm, and the fuel cell membrane electrode prepared from the high-temperature fuel cell proton exchange membrane can be stably operated under the condition of 160 DEG C, and the highest power density can reach 1.1 W / cm 2 .

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of proton exchange membranes, and particularly relates to a preparation method and application of a high-temperature fuel cell proton exchange membrane. BACKGROUND

[0002] As a key carrier for realizing the conversion of hydrogen energy from chemical energy to electrical energy, high-temperature fuel cells have excellent characteristics such as high energy efficiency, environmental friendliness, low noise and stable energy supply, and are considered as one of the most environmentally friendly and efficient power generation technologies in the 21st century. In the past 30 years, the development of fuel cells has been promoted to the level of national strategy in many countries in the world, especially in the field of transportation. Among various fuel cell technologies, proton exchange membrane fuel cells (PEMFC) can be used as power sources for various air, land and marine vehicles due to their light weight, high power density and rapid start-up, and play an important role in the adjustment of global energy structure. The currently widely commercialized PEMFC uses a perfluorosulfonic acid (Nafion) based membrane as a proton exchange membrane, but these cells can only work at a relatively low temperature (i.e., <80℃) and a high relative humidity (i.e., >80%RH), and the PEMFC system needs complex water and heat management accessories, which reduces the energy efficiency of the entire system. High-temperature proton exchange membrane fuel cells (HT-PEMFC) have the advantages of high energy efficiency, good tolerance to air impurities in fuel and convenient water and heat management, and are a very promising energy device that can improve the shortcomings of the current low-temperature PEMFC. However, as a key material of HT-PEMFC, high-temperature proton exchange membrane (HT-PEM) has poor performance under low humidity conditions at high temperature (120-250℃), and its high cost and low durability are still challenges for the practical application of the technology. Phosphoric acid (PA) doped PBI membrane is considered to be the most promising candidate material for high-temperature proton exchange membrane. However, during the operation of high-temperature fuel cells, excessive PA can cause phosphoric acid leakage, corrosion of membrane electrodes and reduction of mechanical properties of the membrane, as well as reduction of proton conductivity, which affects the overall performance of the fuel cell.

[0003] To solve the above problems, CN108183250A discloses a mesoporous SiO2 composite PBI-PA composite membrane, which improves the proton conductivity, but the PBI membrane still has insufficient phosphoric acid retention capacity, and the tensile strength of the phosphoric acid doped PBI membrane is only 13 MPa, which cannot meet the long-term operation of high-temperature fuel cells.

[0004] CN112086673A discloses a method for doping sheet layer C3N4 in the film, which can improve the proton conductivity under low humidity conditions, but due to the limitation of the doping ratio of sheet layer C3N4 and PBI polymer, the phosphoric acid doping amount is still low, the highest level of proton conductivity of the example composite film is 0.053 S / cm, and the highest level of mechanical tensile strength is 18.9 MPa, which still cannot meet the actual application requirements of HT-PEMFC.

[0005] A new PBI-COF containing benzimidazole unit was disclosed in German Angewandte Chemie in 2021, which is a COF powder framework material obtained by embedding benzimidazole (BI) unit into COF. The test condition is to form a wafer by high pressure, although the PBI-COF wafer doped with phosphoric acid has high proton conductivity, but the powder material is not a polymer chain, and PBI-COF cannot form a PBI film with excellent mechanical properties, which is difficult to run stably in a proton exchange membrane fuel cell, and cannot meet the actual application requirements of HT-PEMFC.

[0006] In summary, there is still a lack of a high-temperature fuel cell proton exchange membrane with high phosphoric acid retention capacity, high proton conductivity, high thermal stability, high dimensional stability, high mechanical strength, and long-term stable service life. SUMMARY

[0007] The purpose of the present application is to solve the above-mentioned problems existing in the prior art, and to provide a preparation technology of N-COF modified PBI-based high-temperature fuel cell proton exchange membrane applied to high-temperature proton exchange membrane fuel cell. The N-COF modified PBI composite membrane has high proton conductivity, high mechanical strength, high thermal stability, high phosphoric acid retention capacity, high dimensional stability, and can be applied to fuel cell and can run for a long time.

[0008] To achieve the above-mentioned purpose, the technical scheme of the present application is as follows:

[0009] A preparation method of a high-temperature fuel cell proton exchange membrane, wherein the N-COF-PBI membrane is immersed in a phosphoric acid solution to obtain a high-temperature fuel cell proton exchange membrane;

[0010] The raw material of the N-COF-PBI membrane is N-COF-PBI;

[0011] N-COF-PBI is obtained by mixing the reaction monomers of PBI with N-COF and then performing in-situ covalent condensation polymerization;

[0012] N-COF is a COF with nitrogen channel structure (i.e. nitrogen in the inner wall of the channel), which can chemically react with the reaction monomer of PBI during the in-situ covalent condensation reaction and can interact with phosphoric acid (which can be the acid-base interaction between COF and N-channel, or the hydrogen bond interaction or cross-linking interaction between COF branch and phosphoric acid) to inhibit the loss of phosphoric acid.

[0013] As a preferred technical solution:

[0014] The preparation method of the high-temperature fuel cell proton exchange membrane as described above, the reaction monomer of PBI is 3,4-diaminobenzoic acid, or a mixture of A and B in a molar ratio of 1:1, A is 3,3-diaminobenzene tetrahydrochloride dihydrate or 3,3',4,4'-tetraaminobiphenyl, and B is isophthalic acid, terephthalic acid, 4,4'-oxybis(benzoic acid) or pyridine dicarboxylic acid. Common reaction monomers of PBI can be used in the present application, which are only used as examples here.

[0015] One or more of the above, wherein R is -OH, -NH2, or C1-C4 alkyl.

[0016] The preparation method of the high-temperature fuel cell proton exchange membrane as described above, the preparation process of N-COF-PBI is: under the protection of nitrogen or inert gas, N-COF is added to solvent I and stirred at 60-100℃ for 1-3h to obtain solution S1, the reaction monomer of PBI is added to solution S1 and stirred at 100-140℃ for 1-3h to obtain solution S2, then heated to 200-220℃ and reacted for 6-24h, washed with solvent II to remove solvent I and impurities, and dried in an oven at 50-120℃ to obtain N-COF-PBI.

[0017] The preparation method of the high-temperature fuel cell proton exchange membrane as described above, the N-COF is a powder with a pore size of 1-5nm; the solvent I is one or more of PPA (polyphosphoric acid), MSA (methane sulfonic acid) and P2O5; the solvent II is one or more of deionized water or weakly basic solvent; the content of N-COF in N-COF-PBI is 5-20wt%; and the total solid content of the reaction monomer of PBI and N-COF in solution S2 is 2-20%.

[0018] The preparation method of the high-temperature fuel cell proton exchange membrane as described above, the preparation process of N-COF-PBI membrane is: N-COF-PBI is dissolved in solvent III, stirred and heated to 60-95℃ for 3-6h to obtain solution S3, and then solution S3 is prepared into N-COF-PBI membrane by scraping coating method, casting method or pouring method.

[0019] The preparation method of the high-temperature fuel cell proton exchange membrane according to any one of the above, wherein the solvent III is one or more of methane sulfonic acid, TFA (trifluoroacetic acid), sulfuric acid, FA (formic acid) and DMAc (N,N-dimethylacetamide); and the concentration of the solution S3 is 3-12 wt%.

[0020] The preparation method of the high-temperature fuel cell proton exchange membrane according to any one of the above, wherein the concentration of the phosphoric acid solution is 8-12 M; the mass ratio of the N-COF-PBI membrane to the phosphoric acid solution is not limited, as long as the N-COF-PBI membrane is completely immersed in the phosphoric acid solution; the temperature of the immersion is 20-50 DEG C, and the time is 1-4 days; after the immersion, the phosphoric acid doping amount of the N-COF-PBI membrane is 60-300 wt%, and the volume swelling rate is 1-30%; the phosphoric acid doping amount affects the conductivity, and the higher the doping amount, the higher the conductivity; the interaction between the phosphoric acid and the N-COF-PBI molecular chain affects the phosphoric acid retention capacity; the more the nitrogen-containing basic sites of the N-COF, the stronger the phosphoric acid retention capacity, and the nitrogen-containing pore channels enhance the acid retention capacity by "anchoring" the phosphoric acid.

[0021] The application further provides a high-temperature fuel cell proton exchange membrane prepared by the preparation method of the high-temperature fuel cell proton exchange membrane according to any one of the above.

[0022] As a preferred technical solution,

[0023] The high-temperature fuel cell proton exchange membrane according to any one of the above, wherein the thickness of the high-temperature fuel cell proton exchange membrane is 10-50 mu m.

[0024] The high-temperature fuel cell proton exchange membrane according to any one of the above, wherein the proton conductivity of the high-temperature fuel cell proton exchange membrane is 0.1-0.3 S / cm, the tensile strength is 60-120 MPa, and the thermal decomposition temperature is 450-550 DEG C; the nitrogen pore channel structure can interact with the phosphoric acid, thereby adsorbing and fixing the phosphoric acid to the maximum extent, reducing the loss of the phosphoric acid, and the rigid structure of the N-COF can sufficiently share the external stress, thereby improving the mechanical strength of the composite membrane.

[0025] The application further provides a high-temperature fuel cell membrane electrode comprising the high-temperature fuel cell proton exchange membrane according to any one of the above.

[0026] The application further provides a high-temperature fuel cell comprising the high-temperature fuel cell proton exchange membrane according to any one of the above.

[0027] The application designs an in-situ preparation method of N-COF with 1D nanochannel and PBI material with rich nitrogen sites, and a proton exchange membrane is prepared by using the same as raw material. The rich nitrogen sites, specific 1D nanochannel and diverse structure of COF make the generated N-COF become an ideal platform for limiting and stabilizing H3PO4 in the pore through hydrogen bond interaction, and the combination with PBI triggers the multi-point, multi-chain and multi-type interaction with H3PO4, thereby improving the phosphoric acid retention capacity, proton conductivity and life stability of the membrane. In addition, the in-situ preparation process has significant advantages in continuous multi-phase structure and good multi-component dispersion, and the terminal amino group of the N-COF and the carboxyl group of the monomer of polybenzimidazole can react to form covalently linked N-COF-PBI in the in-situ preparation process, thereby enhancing the intermolecular interaction between PBI and COF, reducing the swelling rate of the N-COF-PBI membrane after phosphoric acid doping, improving the mechanical strength of the phosphoric acid doped membrane, and the membrane with high conductivity and high mechanical strength prolongs the membrane electrode life of the PEMFC.

[0028] Advantages:

[0029] (1) The preparation method of the high-temperature fuel cell proton exchange membrane is simple and convenient.

[0030] (2) The high-temperature fuel cell proton exchange membrane has high proton conductivity, high mechanical strength, high thermal stability, high phosphoric acid retention capacity, high dimensional stability, and long stable life.

[0031] (3) The high-temperature fuel cell membrane electrode can be stably operated at high temperature (> 150℃), and the power density can be as high as 1.1 W / cm 2 . DETAILED DESCRIPTION

[0032] The application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the application and not to limit the scope of the application. In addition, it should be understood that those skilled in the art can make various modifications or changes to the application after reading the content taught by the application, and these equivalent forms also fall within the scope of the claims attached to the present application.

[0033] The manufacturers and brands of the relevant substances in the following examples are as follows:

[0034] 3,4-diaminobenzoic acid: the manufacturer is Shanghai Aladdin Biochemical Technology Co., Ltd., and the brand is D139094-25g;

[0035] 3,3-diaminobenzidine tetrahydrochloride dihydrate: the manufacturer is Shanghai Aladdin Biochemical Technology Co., Ltd., and the brand is D191429-5g;

[0036] 3,3',4,4'-tetraminobiphenyl: manufacturer Shanghai Aldrin Biochemical Science and Technology Co., Ltd.

[0037] isophthalic acid: manufacturer Shanghai Aldrin Biochemical Science and Technology Co., Ltd.

[0038] terephthalic acid: manufacturer Shanghai Aldrin Biochemical Science and Technology Co., Ltd.

[0039] 4,4'-oxybis(benzoic acid): manufacturer Shanghai Aldrin Biochemical Science and Technology Co., Ltd.

[0040] pyridinedicarboxylic acid: manufacturer Shanghai Aldrin Biochemical Science and Technology Co., Ltd.

[0041] PPA: manufacturer Shanghai Aldrin Biochemical Science and Technology Co., Ltd., brand P102919-500g

[0042] MSA: manufacturer Shanghai Aldrin Biochemical Science and Technology Co., Ltd.

[0043] TFA: manufacturer Shanghai Aldrin Biochemical Science and Technology Co., Ltd.

[0044] FA: manufacturer Shanghai Aldrin Biochemical Science and Technology Co., Ltd.

[0045] DMAc: manufacturer Shanghai Aldrin Biochemical Science and Technology Co., Ltd.

[0046] sulfuric acid: concentration 98%;

[0047] cyclohexanehexone octahydrate: manufacturer Shanghai Aldrin Biochemical Science and Technology Co., Ltd.

[0048] 1,2,4,5-benzene tetramine tetrahydrochloride: manufacturer Shanghai Aldrin Biochemical Science and Technology Co., Ltd.

[0049] N-methylpyrrolidone: manufacturer Shanghai Aldrin Biochemical Science and Technology Co., Ltd.

[0050] 1,4-dioxane: manufacturer Shanghai Aldrin Biochemical Science and Technology Co., Ltd.

[0051] mesitylene: manufacturer Shanghai Aldrin Biochemical Science and Technology Co., Ltd.

[0052] 2,5-dimethyl-p-xylylene glycol: manufacturer Shanghai Aldrin Biochemical Science and Technology Co., Ltd.

[0053] 1,3,6,8-tetrakis(p-benzoic acid)pyrene: manufacturer Shanghai Aldrin Biochemical Science and Technology Co., Ltd.

[0054] 1,3,5-tris(4-aminophenyl): manufacturer Shanghai Aldrin Biochemical Science and Technology Co., Ltd.

[0055] 1,4-benzene diboronic acid: the manufacturer is Shanghai Aladdin Bio-Chem Technology Co., Ltd.;

[0056] sodium bicarbonate: the manufacturer is Shanghai Aladdin Bio-Chem Technology Co., Ltd.;

[0057] o-dichlorobenzene: the manufacturer is Shanghai Aladdin Bio-Chem Technology Co., Ltd.;

[0058] n-butanol: the manufacturer is Shanghai Aladdin Bio-Chem Technology Co., Ltd.

[0059] The detection method of the relevant performance in the following examples and comparative examples is as follows:

[0060] The detection method of proton conductivity: the conductivity of each group of films was tested by using the Concept 40 wide frequency dielectric test system of Germany Novocontrol Technologies Co., Ltd.; before testing, each group of film samples was cut into a square of 1.2 cm x 1.2 cm, clamped between two bronze electrodes with a diameter of 10 mm, and the proton conductivity of the film was measured at a frequency of 10 MHz;

[0061] Tensile strength: the film sample was cut into a rectangle of 5 x 30 mm, and the tensile strength of the film sample was tested by using the INSTRON / 5969 electronic universal testing machine, wherein the sensor was 1 KN;

[0062] Thermal decomposition temperature: 3-8 mg samples of each group of films were taken, and the thermal gravimetric curve was tested by using the thermal gravimetric analyzer (Libra / TG209F1 Libra) under the nitrogen atmosphere at a heating rate of 10 ℃min -1 From 50 ℃ to 800 ℃, the thermal decomposition temperature was obtained;

[0063] Phosphoric acid doping amount: the phosphoric acid doping amount (ADL) was calculated according to the formula ADL (%) = [(m a -m0) / m0]x100%;

[0064] Volume swelling rate: the volume swelling rate was calculated according to the formula volume swelling rate SW (%) = [(T a -T0) / T0]x100%.

[0065] Example 1

[0066] A preparation method of N-COF, first, cyclohexanehexaketone octahydrate and 1,2,4,5-benzene tetramine tetrahydrochloride with a molar ratio of 3:2 are dissolved in N-methyl pyrrolidone to obtain a mixed solution, the total mass concentration of cyclohexanehexaketone octahydrate and 1,2,4,5-benzene tetramine tetrahydrochloride in the mixed solution is 0.075 g / mL, then heated to 120 DEG C, refluxed, reacted for 5 days, filtered under reduced pressure, washed with water and acetone alternately, and the number of washing is 3 times, then hot extracted with methanol at a temperature of 80 DEG C, and finally dried in a vacuum oven at 60 DEG C, to obtain N-COF-1 (structural formula as follows) with a pore size of 1.9 nm.

[0067]

[0068] Example 2

[0069] A preparation method of N-COF, first, 480 mg of p-phenylenediformic aldehyde (PDA) and 520 mg of melem are dissolved in 30 mL of a solvent (a mixed solution of 1,4-dioxane and mesitylene with a volume ratio of 4:1), stirred at room temperature for 1 h to form a uniform suspension, 1.8 mL of acetic acid is added under a nitrogen atmosphere, then heated to 110 DEG C, and the reaction is continued for 72 h until the reaction is completed, the product is separated by centrifugation, washed with tetrahydrofuran and ethanol alternately for 4 times, and finally dried in a vacuum oven at 60 DEG C, to obtain N-COF-2 (structural formula as follows) with a pore size of 1.5 nm.

[0070]

[0071] Example 3

[0072] A preparation method of N-COF, first, 788 mg of 4,4'-diphenylformic aldehyde and 545 mg of melem are dissolved in 30 mL of a solvent (a mixed solution of 1,4-dioxane and mesitylene with a volume ratio of 4:1), stirred at room temperature for 1 h to form a uniform suspension, 2.5 mL of acetic acid is added under a nitrogen atmosphere, then heated to 120 DEG C, and the reaction is continued for 72 h until the reaction is completed, the product is separated by centrifugation, washed with tetrahydrofuran and ethanol alternately for 4 times, and finally dried in a vacuum oven at 60 DEG C, to obtain N-COF-3 (structural formula as follows) with a pore size of 2.5 nm.

[0073]

[0074] Example 4

[0075] A preparation method of N-COF, 196 mg of 1,3,5-tris(4-aminophenyl) and 136.8 mg of 2,5-dimethyl-p-xylylene glycol and 0.6 mL of 6M acetic acid aqueous solution are dissolved in o-dichlorobenzene / n-butanol (3 mL / 3 mL) in a 25 mL two-necked flask, and the reaction is heated to 120°C under nitrogen atmosphere, after 72 h of reaction, the product is obtained by filtration and washing with water, methanol, and drying in a vacuum oven at 100°C for 6 h to obtain N-COF-4 (structure formula as follows) with a pore size of 3.3 nm.

[0076]

[0077] Example 5

[0078] A preparation method of N-COF, 500 mg of 1,3,6,8-tetrakis(p-benzoic acid) pyrene and 425 mg of 1,2,4,5-benzene tetramine tetrahydrochloride are dissolved in 75 mL of polyphosphoric acid (PPA), stirred at room temperature for 1 h, heated to 150°C for 24 h, and then stirred at 180°C for 24 h, the PH of the solution in the reaction bottle is adjusted to 9 with saturated sodium bicarbonate (NaHCO3), and the precipitated compound is obtained, filtered and washed with water, methanol and acetone for 5 times, and dried in a vacuum oven at 100°C for 6 h to obtain N-COF-5 (structure formula as follows) with a pore size of 1.6 nm.

[0079]

[0080] Example 6

[0081] A preparation method of a high-temperature fuel cell proton exchange membrane, the specific steps are as follows:

[0082] (1) Preparation of raw materials:

[0083] PBI reaction monomer: 3,4-diaminobenzoic acid;

[0084] N-COF: prepared by Example 2;

[0085] Phosphoric acid solution: concentration of 11M;

[0086] Solvent I: PPA;

[0087] Solvent II: deionized water;

[0088] Solvent III: MSA;

[0089] (2) Preparation of N-COF-PBI:

[0090] N-COF is added into solvent I under nitrogen protection, stirred at 90℃ for 2h to obtain solution S1, the reaction monomer of PBI is added into solution S1, stirred at 140℃ for 2h to obtain solution S2, then heated to 210℃ for 12h, washed with solvent II to remove solvent I and impurities, and dried in an oven at 60℃ to obtain N-COF-PBI; wherein the total solid content of the reaction monomer of PBI and N-COF in solution S2 is 5%, and the content of N-COF in N-COF-PBI is 10wt%;

[0091] (3) Preparation of N-COF-PBI membrane:

[0092] N-COF-PBI prepared in step (2) is dissolved in solvent III, stirred at a stirring rate of 500rpm and heated to 90℃ for 6h to obtain solution S3, a film is prepared by using a doctor blade method, solution S3 is cast on a glass plate matched with the doctor blade to form a film, and the film is immediately immersed in solvent II after film formation, washed for 5 times, and then dried in an oven at 60℃ to obtain N-COF-PBI membrane; wherein the concentration of solution S3 is 4wt%;

[0093] (4) Preparation of high-temperature fuel cell proton exchange membrane:

[0094] N-COF-PBI membrane prepared in step (3) is dried in a vacuum oven at 80℃ for 12h, weighed and the mass is recorded as m0, and the thickness is recorded as T0, immersed in a phosphoric acid solution, immersed at 20℃ for 2 days, dried in a vacuum oven at 80℃ for 12h, weighed and the mass is recorded as m a , and the thickness is recorded as T a , to obtain a high-temperature fuel cell proton exchange membrane; wherein the mass ratio of N-COF-PBI membrane to phosphoric acid solution is not limited, as long as the N-COF-PBI membrane is completely immersed in the phosphoric acid solution, the phosphoric acid doping amount of N-COF-PBI membrane is 165wt%, and the volume swelling rate is 1%.

[0095] The thickness of the finally prepared high-temperature fuel cell proton exchange membrane is 35μm, the proton conductivity is 0.3S / cm, the tensile strength is 65MPa, and the thermal decomposition temperature is 480℃, and after the membrane electrode of the high-temperature fuel cell is continuously applied with a voltage of 0.6V for 500h at 160℃, the current density of the high-temperature fuel cell proton exchange membrane remains constant.

[0096] A high-temperature fuel cell membrane electrode comprising the high-temperature fuel cell proton exchange membrane.

[0097] A high-temperature fuel cell comprising the high-temperature fuel cell proton exchange membrane.

[0098] Comparative Example 1

[0099] A method for preparing a proton exchange membrane, substantially as in Example 6, except that Comparative Example 1 corresponds to replacing the N-COF of Example 6 with an equal molar amount of O-COF.

[0100] O-COF does not have N channel structure, and has the following structure:

[0101]

[0102] The method for preparing O-COF is as follows: 500 mg of 1,4-phenyldiboronic acid is dissolved in 1,4-dioxane / trimethylbenzene (10 mL / 10 mL), and a uniform solution is obtained by stirring for 0.5 h under nitrogen. The solution is then transferred to a 100 mL teflon reaction kettle and reacted at 120°C for 72 h. A white precipitate is obtained after filtration and washing. The precipitate is washed with water, methanol and acetone for 5 times, and then dried in a vacuum oven at 100°C for 6 h to obtain O-COF with a pore size of 1.5 nm.

[0103] The final proton exchange membrane has a thickness of 50 μm, a proton conductivity of 0.053 S / cm, a tensile strength of 21 MPa, and a thermal decomposition temperature of 430°C.

[0104] Comparative Example 1 has a tensile strength of only about 1 / 3 of Example 6 and a proton conductivity of only about 1 / 6 of Example 6, because the COF used in Comparative Example 1 has the same pore size as the COF used in Example 6, but the channel structure of O-COF does not contain N, and the hydrogen bond interaction between the channel and phosphoric acid is weak, which reduces the density of the hydrogen bond network in the PBI composite membrane, hinders the proton conduction, and thus reduces the conductivity of the proton exchange membrane. In addition, the terminal of O-COF does not have a group that can form a covalent bond with PBI, and the intermolecular interaction between O-COF and PBI is small, which further reduces the mechanical strength of the phosphoric acid doped membrane.

[0105] Example 7

[0106] A method for preparing a proton exchange membrane for a high-temperature fuel cell, and the specific steps are as follows:

[0107] (1) Prepare raw materials:

[0108] The reaction monomer of PBI is 3,4-diaminobenzoic acid;

[0109] N-COF: prepared according to Example 1;

[0110] Phosphoric acid solution: concentration of 9M;

[0111] Solvent I: MSA;

[0112] Solvent II: deionized water;

[0113] Solvent III: TFA;

[0114] (2) Preparation of N-COF-PBI:

[0115] N-COF was added into solvent I under argon protection and stirred at 70℃ for 3h to obtain solution S1, and the reaction monomer of PBI was added into solution S1 and stirred at 140℃ for 1h to obtain solution S2, then the temperature was raised to 200℃ for 18h, and solvent I and impurities were removed by washing with solvent II, and then dried in an oven at 50℃ to obtain N-COF-PBI; wherein the total solid content of the reaction monomer of PBI and N-COF in solution S2 was 5%, and the content of N-COF in N-COF-PBI was 5wt%;

[0116] (3) Preparation of N-COF-PBI membrane:

[0117] N-COF-PBI prepared in step (2) was dissolved in solvent III, stirred at a stirring rate of 500rpm and heated to 60℃ for 6h to obtain solution S3, and then the solution S3 was cast on a glass plate by casting method, dried on a hot plate, immersed in solvent II after the membrane was completely dried, then the membrane was peeled off from the glass plate, and dried in an oven at 50℃ to obtain N-COF-PBI membrane; wherein the concentration of solution S3 was 3wt%;

[0118] (4) Preparation of high-temperature fuel cell proton exchange membrane:

[0119] N-COF-PBI membrane prepared in step (3) was dried in a vacuum oven at 80℃ for 12h, and the mass was recorded as m0 and the thickness was recorded as T0, then immersed in a phosphoric acid solution, and after immersion at 30℃ for 3 days, dried in a vacuum oven at 80℃ for 12h, and the mass was recorded as m a and the thickness was recorded as T a , to obtain a high-temperature fuel cell proton exchange membrane; wherein the mass ratio of N-COF-PBI membrane to phosphoric acid solution was not limited, as long as the N-COF-PBI membrane was completely immersed in the phosphoric acid solution, the phosphoric acid doping amount of N-COF-PBI membrane was 60wt%, and the volume swelling rate was 25%.

[0120] The thickness of the finally prepared high-temperature fuel cell proton exchange membrane was 30μm, the proton conductivity was 0.23S / cm, the tensile strength was 90MPa, the thermal decomposition temperature was 450℃, and after the membrane electrode based on the high-temperature fuel cell proton exchange membrane was continuously applied with a voltage of 0.6V for 500h at 160℃, the current density of the high-temperature fuel cell proton exchange membrane remained constant.

[0121] A high-temperature fuel cell membrane electrode comprising the high-temperature fuel cell proton exchange membrane described above.

[0122] A high-temperature fuel cell includes the aforementioned high-temperature fuel cell proton exchange membrane.

[0123] Example 8

[0124] A method for preparing a proton exchange membrane for a high-temperature fuel cell, comprising the following specific steps:

[0125] (1) Prepare raw materials:

[0126] The reactive monomers of PBI are a mixture of 3,3-diaminobenzidine tetrahydrochloride dihydrate and isophthalic acid in a molar ratio of 1:1.

[0127] N-COF: prepared from Example 2;

[0128] Phosphoric acid solution: 10M concentration;

[0129] Solvent I: P2O5;

[0130] Solvent II: Deionized water;

[0131] Solvent III: Sulfuric acid;

[0132] (2) Preparation of N-COF-PBI:

[0133] Under helium protection, N-COF was added to solvent I and stirred at 70°C for 3 hours to obtain solution S1. The reactant monomer of PBI was added to solution S1 and stirred at 130°C for 3 hours to obtain solution S2. The solution was then heated to 210°C and reacted for 20 hours. Solvent I and impurities were removed by washing with solvent II, and the solution was dried in an oven at 90°C to obtain N-COF-PBI. The total solid content of reactant monomer of PBI and N-COF in solution S2 was 2%, and the content of N-COF in N-COF-PBI was 15 wt%.

[0134] (3) Preparation of N-COF-PBI membrane:

[0135] The N-COF-PBI obtained in step (2) was dissolved in solvent III, stirred at a stirring rate of 500 rpm and heated to 70°C for 4 hours to obtain solution S3. A film was formed by casting, and solution S3 was injected into the casting substrate. The film with a certain thickness was formed on the glass plate by the movement of the casting knife. After the film was formed, it was immediately immersed in solvent II and washed 3 times. The film was then dried in an oven at 60°C to obtain the N-COF-PBI film. The concentration of solution S3 was 10 wt%.

[0136] (4) Preparation of proton exchange membrane for high-temperature fuel cells:

[0137] The N-COF-PBI film prepared in step (3) is dried in a vacuum oven at 80℃ for 12h, and the mass is recorded as m0 and the thickness is recorded as T0. The N-COF-PBI film is immersed in a phosphoric acid solution, and after being immersed at 20℃ for 4 days, it is dried in a vacuum oven at 80℃ for 12h, and the mass is recorded as m and the thickness is recorded as T a , wherein the mass ratio of the N-COF-PBI film to the phosphoric acid solution is not limited, as long as the N-COF-PBI film is completely immersed in the phosphoric acid solution, the phosphoric acid doping amount of the N-COF-PBI film is 120wt%, and the volume swelling rate is 14%. a , wherein the mass ratio of the N-COF-PBI film to the phosphoric acid solution is not limited, as long as the N-COF-PBI film is completely immersed in the phosphoric acid solution, the phosphoric acid doping amount of the N-COF-PBI film is 120wt%, and the volume swelling rate is 14%.

[0138] The thickness of the finally prepared high-temperature fuel cell proton exchange membrane is 25μm, the proton conductivity is 0.28S / cm, the tensile strength is 100MPa, and the thermal decomposition temperature is 490℃. After the membrane electrode of the high-temperature fuel cell proton exchange membrane is continuously subjected to a voltage of 0.6V at 160℃ for 500h, the current density of the high-temperature fuel cell proton exchange membrane remains constant.

[0139] A high-temperature fuel cell membrane electrode comprising the high-temperature fuel cell proton exchange membrane described above.

[0140] A high-temperature fuel cell comprising the high-temperature fuel cell proton exchange membrane described above.

[0141] Example 9

[0142] A method for preparing a high-temperature fuel cell proton exchange membrane, the specific steps of which are as follows:

[0143] (1) Prepare raw materials:

[0144] PBI reaction monomer: a mixture of 3,3-diaminobenzidine tetrahydrochloride dihydrate and terephthalic acid in a molar ratio of 1:1;

[0145] N-COF: prepared in Example 3;

[0146] Phosphoric acid solution: concentration of 10M;

[0147] Solvent I: a mixture of PPA and MSA in a mass ratio of 1:1;

[0148] Solvent II: 1M aqueous sodium hydroxide solution;

[0149] Solvent III: FA;

[0150] (2) Preparation of N-COF-PBI:

[0151] N-COF is added into solvent I under neon protection, stirred at 80℃ for 3h to obtain solution S1, the reaction monomer of PBI is added into solution S1, stirred at 130℃ for 3h to obtain solution S2, then heated to 220℃ for 6h, solvent I and impurities are removed by washing with solvent II, and dried in an oven at 80℃ to obtain N-COF-PBI; wherein the total solid content of the reaction monomer of PBI and N-COF in solution S2 is 10%, and the content of N-COF in N-COF-PBI is 20wt%;

[0152] (3) Preparation of N-COF-PBI membrane:

[0153] N-COF-PBI prepared in step (2) is dissolved in solvent III, stirred at a stirring rate of 500rpm and heated to 80℃ for 5h to obtain solution S3, a film is prepared by using a doctor blade method, solution S3 is cast on a glass plate matched with the doctor blade, and the film is immediately immersed in solvent II after film formation, washed for 5 times, and then dried in an oven at 70℃ to obtain N-COF-PBI membrane; wherein the concentration of solution S3 is 10wt%;

[0154] (4) Preparation of high-temperature fuel cell proton exchange membrane:

[0155] N-COF-PBI membrane prepared in step (3) is dried in a vacuum oven at 80℃ for 12h, weighed and the mass is recorded as m0, the thickness is recorded as T0, immersed in a phosphoric acid solution, immersed at 40℃ for 3 days, dried in a vacuum oven at 80℃ for 12h, weighed and the mass is recorded as m a , the thickness is recorded as T a , to obtain a high-temperature fuel cell proton exchange membrane; wherein the mass ratio of N-COF-PBI membrane to phosphoric acid solution is not limited, as long as the N-COF-PBI membrane is completely immersed in the phosphoric acid solution, the phosphoric acid doping amount of N-COF-PBI membrane is 200wt%, and the volume swelling rate is 30%.

[0156] The thickness of the finally prepared high-temperature fuel cell proton exchange membrane is 30μm, the proton conductivity is 0.2S / cm, the tensile strength is 105MPa, the thermal decomposition temperature is 505℃, and the current density of the high-temperature fuel cell proton exchange membrane remains constant after the membrane electrode of the high-temperature fuel cell is continuously applied with a voltage of 0.6V at 160℃ for 500h.

[0157] A high-temperature fuel cell membrane electrode comprises the high-temperature fuel cell proton exchange membrane.

[0158] A high-temperature fuel cell comprises the high-temperature fuel cell proton exchange membrane.

[0159] Example 10

[0160] A method for preparing a high-temperature fuel cell proton exchange membrane, the specific steps are as follows:

[0161] (1) Prepare raw materials:

[0162] PBI reaction monomer: mixture of 3,3',4,4'-tetraaminobiphenyl and 4,4'-oxybis(benzoic acid) with a molar ratio of 1:1;

[0163] N-COF: prepared from Example 4;

[0164] Phosphoric acid solution: concentration of 8M;

[0165] Solvent I: MSA;

[0166] Solvent II: 1M aqueous sodium hydroxide solution;

[0167] Solvent III: mixture of TFA and FA with a mass ratio of 1:1;

[0168] (2) Preparation of N-COF-PBI:

[0169] Under the protection of nitrogen, N-COF was added to solvent I and stirred at 90℃ for 2h to obtain solution S1, and the PBI reaction monomer was added to solution S1 and stirred at 100℃ for 3h to obtain solution S2, then the temperature was raised to 210℃ and reacted for 24h, and solvent I and impurities were removed by washing with solvent II, and then dried in an oven at 100℃ to obtain N-COF-PBI; wherein the total solid content of PBI reaction monomer and N-COF in solution S2 is 15%, and the content of N-COF in N-COF-PBI is 10wt%;

[0170] (3) Preparation of N-COF-PBI membrane:

[0171] The N-COF-PBI prepared in step (2) was dissolved in solvent III, stirred at a stirring rate of 500rpm and heated to 95℃ for 3h to obtain solution S3, then the solution S3 was cast on a glass plate matched with a film coater to form a film, and the film was immediately immersed in solvent II after film formation, washed 5 times, and then dried in an oven at 40℃ to obtain N-COF-PBI membrane; wherein the concentration of solution S3 is 10wt%;

[0172] (4) Preparation of high-temperature fuel cell proton exchange membrane:

[0173] The N-COF-PBI membrane prepared in step (3) was dried in a vacuum oven at 80℃ for 12h, weighed and the mass was recorded as m0, the thickness was recorded as T0, and then immersed in a phosphoric acid solution, and after immersion at 50℃ for 1 day, dried in a vacuum oven at 80℃ for 12h, weighed and the mass was recorded as m a, thickness is T a The high-temperature fuel cell proton exchange membrane is obtained; wherein the mass ratio of the N-COF-PBI membrane to the phosphoric acid solution is not limited, as long as the N-COF-PBI membrane is completely immersed in the phosphoric acid solution, the phosphoric acid doping amount of the N-COF-PBI membrane is 170wt%, and the volume swelling rate is 28%.

[0174] The thickness of the finally prepared high-temperature fuel cell proton exchange membrane is 40μm, the proton conductivity is 0.19S / cm, the tensile strength is 40MPa, the thermal decomposition temperature is 495℃, and the current density of the high-temperature fuel cell proton exchange membrane remains constant after the membrane electrode of the high-temperature fuel cell proton exchange membrane is continuously subjected to a voltage of 0.6V for 500h at 160℃.

[0175] A high-temperature fuel cell membrane electrode comprising the high-temperature fuel cell proton exchange membrane.

[0176] A high-temperature fuel cell comprising the high-temperature fuel cell proton exchange membrane.

[0177] Example 11

[0178] A preparation method of a high-temperature fuel cell proton exchange membrane, the specific steps are as follows:

[0179] (1) Prepare raw materials:

[0180] PBI reaction monomer: mixture of 3,3',4,4'-tetraaminobiphenyl and pyridine dicarboxylic acid with a molar ratio of 1:1;

[0181] N-COF: prepared by Example 5;

[0182] Phosphoric acid solution: concentration is 12M;

[0183] Solvent I: MSA;

[0184] Solvent II: 1M sodium hydroxide aqueous solution;

[0185] Solvent III: DMAc;

[0186] (2) Preparation of N-COF-PBI:

[0187] N-COF is added into solvent I under argon protection, stirred at 100℃ for 1h to obtain solution S1, the reaction monomer of PBI is added into solution S1, stirred at 120℃ for 3h to obtain solution S2, then heated to 210℃ for 10h, solvent I and impurities are removed by washing with solvent II, and dried in an oven at 120℃ to obtain N-COF-PBI; wherein the total solid content of the reaction monomer of PBI and N-COF in solution S2 is 20%, and the content of N-COF in N-COF-PBI is 10wt%;

[0188] (3) Preparation of N-COF-PBI membrane:

[0189] N-COF-PBI prepared in step (2) is dissolved in solvent III, stirred at a stirring rate of 500rpm and heated to 80℃ for 6h to obtain solution S3, a film is prepared by using a doctor blade method, solution S3 is cast on a glass plate matched with the doctor blade, and the film is immediately immersed in solvent II after film formation, washed for 5 times, and then dried in an oven at 60℃ to obtain N-COF-PBI membrane; wherein the concentration of solution S3 is 12wt%;

[0190] (4) Preparation of high-temperature fuel cell proton exchange membrane:

[0191] N-COF-PBI membrane prepared in step (3) is dried in a vacuum oven at 80℃ for 12h, weighed and the mass is recorded as m0, the thickness is recorded as T0, immersed in a phosphoric acid solution, immersed at 25℃ for 3 days, dried in a vacuum oven at 80℃ for 12h, weighed and the mass is recorded as m a , the thickness is recorded as T a , to obtain a high-temperature fuel cell proton exchange membrane; wherein the mass ratio of N-COF-PBI membrane to phosphoric acid solution is not limited, as long as the N-COF-PBI membrane is completely immersed in the phosphoric acid solution, the phosphoric acid doping amount of N-COF-PBI membrane is 300wt%, and the volume swelling rate is 22%.

[0192] The thickness of the finally prepared high-temperature fuel cell proton exchange membrane is 50μm, the proton conductivity is 0.1S / cm, the tensile strength is 120MPa, the thermal decomposition temperature is 550℃, and the current density of the high-temperature fuel cell proton exchange membrane remains constant after the membrane electrode of the high-temperature fuel cell is continuously applied with a voltage of 0.6V for 500h at 160℃.

[0193] A high-temperature fuel cell membrane electrode comprises the high-temperature fuel cell proton exchange membrane.

[0194] A high-temperature fuel cell comprises the high-temperature fuel cell proton exchange membrane.

Claims

1. A method for preparing a proton exchange membrane for a high-temperature fuel cell, characterized in that, The N-COF-PBI membrane is immersed in a phosphoric acid solution to obtain the proton exchange membrane for a high-temperature fuel cell. The raw material for N-COF-PBI membrane is N-COF-PBI; N-COF-PBI is obtained by mixing the reactive monomers of PBI with N-COF and then carrying out an in-situ covalent polycondensation reaction. The reactive monomer of PBI is 3,4-diaminobenzoic acid, or a mixture of A and B in a molar ratio of 1:1, where A is 3,3-diaminobenzidine tetrahydrochloride dihydrate or 3,3',4,4'-tetraaminobiphenyl, and B is isophthalic acid, terephthalic acid, 4,4'-oxobis(benzoic acid) or pyridinedicarboxylic acid. N-COF is , , , , One or more of them, wherein R is -OH, -NH2 or C1~C4 alkyl; N-COF can chemically react with the reactive monomers of PBI during the in-situ covalent polycondensation reaction and can interact with phosphoric acid to inhibit phosphoric acid loss.

2. The method for preparing a proton exchange membrane for a high-temperature fuel cell according to claim 1, characterized in that, The preparation process of N-COF-PBI is as follows: Under the protection of nitrogen or inert gas, N-COF is added to solvent I and stirred at 60~100℃ for 1~3h to obtain solution S1. The reactive monomer of PBI is added to solution S1 and stirred at 100~140℃ for 1~3h to obtain solution S2. Then, the temperature is raised to 200~220℃ and reacted for 6~24h to obtain N-COF-PBI.

3. The method for preparing a proton exchange membrane for a high-temperature fuel cell according to claim 2, characterized in that, N-COF is a powder with a pore size of 1~5nm; solvent I is one or more of PPA, MSA and P2O5; the content of N-COF in N-COF-PBI is 5~20wt%; the total solid content of PBI reaction monomers and N-COF in solution S2 is 2~20%.

4. The method for preparing a proton exchange membrane for a high-temperature fuel cell according to claim 1, characterized in that, The preparation process of N-COF-PBI membrane is as follows: N-COF-PBI is dissolved in solvent III, stirred and heated to 60~95℃ and kept for 3~6h to obtain solution S3. Solution S3 is then used to prepare N-COF-PBI membrane by scraping, casting or casting.

5. The method for preparing a proton exchange membrane for a high-temperature fuel cell according to claim 4, characterized in that, Solvent III is one or more of methanesulfonic acid, TFA, sulfuric acid, FA and DMAc; the concentration of solution S3 is 3~12wt%.

6. The method for preparing a proton exchange membrane for a high-temperature fuel cell according to claim 1, characterized in that, The concentration of the phosphoric acid solution is 8~12M; the impregnation temperature is 20~50℃, and the time is 1~4 days; after impregnation, the phosphoric acid doping amount of the N-COF-PBI film is 60~300wt%, and the volume swelling rate is 1~30%.

7. A proton exchange membrane for a high-temperature fuel cell, characterized in that, The proton exchange membrane for a high-temperature fuel cell is prepared using the method described in any one of claims 1 to 6.

8. A high-temperature fuel cell membrane electrode, characterized in that, Includes the high-temperature fuel cell proton exchange membrane as described in claim 7.

9. A high-temperature fuel cell, characterized in that, Includes the high-temperature fuel cell proton exchange membrane as described in claim 7.

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