A composite high-temperature proton exchange membrane and its preparation method and application

Abstract

The present invention relates to a composite high-temperature proton exchange membrane, a preparation method thereof, and an application thereof. The preparation method of the composite high-temperature proton exchange membrane comprises the following steps: S1. Mix a polymer represented by formula (I), a polymer represented by formula (II), and a solvent to obtain a casting solution, pour it, and dry it to obtain a composite film; S2. Immerse the composite film obtained in step S1 in an alkaline solution of borax, wash it, dry it, and then adsorb phosphoric acid to obtain the composite high-temperature proton exchange membrane. The composite high-temperature proton exchange membrane prepared by the preparation method of the present invention still maintains good proton conductivity / has high proton conductivity, has a high peak power density, and has high tensile strength and high phosphoric acid retention rate under the condition of low phosphoric acid adsorption amount.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer electrolyte membrane materials, and more specifically, to a composite high-temperature proton exchange membrane, a preparation method thereof, and an application thereof. Background Art

[0002] High-temperature fuel cells rely on the function of high-temperature proton exchange membranes to transfer protons and block electrons under high-temperature and low-humidity conditions. The requirements for high-temperature proton exchange membranes are good mechanical properties and high proton transport rates.

[0003] In currently reported cases, a large amount of phosphoric acid is usually added to the high-temperature proton exchange membrane made of polymers as a proton conductor to transfer protons and block electrons, ensuring the long-term operation of the high-temperature proton exchange membrane under high-temperature and low-humidity conditions. Although this method can improve the proton conductivity of the high-temperature proton exchange membrane, the "plasticizing" effect of the high-content proton conductor will weaken the mechanical properties of the polymer, affecting the service life of high-temperature fuel cells. At the same time, under high-temperature and low-humidity conditions, the weak binding ability of the high-temperature proton exchange membrane made of polymers to the proton conductor causes the proton conductor to be easily lost. The loss of the proton conductor not only affects the proton transport rate of the high-temperature proton exchange membrane and the polymer membrane, but also easily "poisons" the catalyst in the membrane electrode, affecting the energy conversion efficiency, service life, and safety performance of the battery.

[0004] The high-temperature proton exchange membrane provided by the prior art (《Intermolecular Acid-Base-Pairs Containing Poly(p-Terphenyl-co-Isatin Piperidinium)for High Temperature Proton Exchange Membrane FuelCells》, Xiaofeng Hao etc.) takes into account good mechanical properties and electrochemical properties. However, with the current higher requirements for product performance in the battery field, the mechanical properties and electrochemical properties of the high-temperature proton exchange provided by this literature need to be further improved. In addition, the content of the proton conductor in the high-temperature proton exchange membrane of this literature is still relatively high and the proton conductor is still easily lost. Summary of the Invention

[0005] The primary object of the present invention is to overcome the problems existing in the above-mentioned prior art and provide a preparation method for a composite high-temperature proton exchange membrane.

[0006] A further object of the present invention is to provide a composite high-temperature proton exchange membrane.

[0007] A further object of the present invention is to provide the application of the above-mentioned composite high-temperature proton exchange membrane in the preparation of high-temperature fuel cells.

[0008] The above object of the present invention is achieved by the following technical solutions:

[0009] A preparation method of a composite high-temperature proton exchange membrane, comprising the following steps:

[0010] S1. Mix a polymer represented by formula (I), a polymer represented by formula (II), and a solvent to obtain a casting solution, pour it, and dry it to obtain a composite film;

[0011] S2. Immerse the composite film obtained in step S1 in an alkaline solution of borax, wash it, dry it, and then adsorb phosphoric acid to obtain the composite high-temperature proton exchange membrane;

[0012]

[0013] In formula (I), 0 < X < 1; Ar is a structure containing an aromatic ring; R is a structure containing a cyclic tertiary amine;

[0014] In step S1, the mass ratio of the polymer represented by formula (I) to the polymer represented by formula (II) is (85 - 95):(5 - 15);

[0015] The number average molecular weight of the polymer represented by formula (II) is 200 - 150000.

[0016] Research shows that directly making the polymer represented by formula (I) into a high-temperature proton exchange membrane, due to the easy limitation of the segmental motion of the polymer represented by formula (I) under high-temperature conditions (the use environment of the high-temperature proton exchange membrane), its electrochemical performance is not good.

[0017] The inventor of the present invention has found through research that adding the polymer represented by formula (II) to the polymer represented by formula (I) to first make a composite film, and then immersing the composite film in an alkaline solution of borax to undergo a cross-linking reaction, and the cross-linking reaction forms a PEG / PEO-B cross-linked network, and the PEG / PEO-B cross-linked network forms a semi-interpenetrating structure with the polymer represented by formula (I). On the one hand, the flexible segment brought by the polymer represented by formula (II) is used to swing at high temperature to reduce the proton transport resistance in the membrane, thereby improving the proton conductivity and peak power density of the composite high-temperature proton exchange membrane under the condition of low phosphoric acid adsorption amount. In addition, due to the low phosphoric acid adsorption amount, the mechanical properties of the composite high-temperature proton exchange membrane are improved; on the other hand, the tertiary amine group of the polymer represented by formula (I) can "anchor" the phosphoric acid proton conductor, and the semi-interpenetrating structure can effectively "trap" the phosphoric acid proton conductor, thereby reducing the loss of phosphoric acid during the operation of the battery.

[0018] Since the polymer shown in formula (II) may have poor stability under high-temperature conditions, it is necessary to crosslink it with borax to form a PEG / PEO-B crosslinked network to improve the stability of the flexible chain segments at high temperatures. Otherwise, the electrochemical performance of the composite high-temperature proton exchange membrane cannot be improved, and the phosphoric acid proton conductor is also likely to be lost.

[0019] The amount of the polymer shown in formula (II) cannot be too much, otherwise it will have a negative impact on the intermolecular force between the polymer shown in formula (I) and the phosphoric acid proton conductor, significantly reducing the adsorption amount of the phosphoric acid proton conductor and decreasing the electrochemical performance and phosphoric acid retention rate of the composite high-temperature proton exchange membrane.

[0020] The molecular weight of the polymer shown in formula (II) cannot be too high, otherwise its compatibility with the polymer shown in formula (II) will become poor, reducing the electrochemical performance, mechanical properties, and phosphoric acid retention rate of the composite high-temperature proton exchange membrane.

[0021] The composite high-temperature proton exchange membrane prepared by the preparation method of the present invention still maintains good proton conductivity / high proton conductivity, high peak power density, high tensile strength, and high phosphoric acid retention rate (i.e., phosphoric acid is not easily lost) under the condition of low phosphoric acid adsorption amount.

[0022] It should be understood that the polymer shown in formula (II) in the present invention refers to polyethylene glycol and / or polyethylene oxide. When the number-average molecular weight of the polymer shown in formula (II) ≤ 20000, it is usually called polyethylene glycol; when the number-average molecular weight of the polymer shown in formula (II) > 20000, it is usually called polyethylene oxide.

[0023] Preferably, Ar is any one of the following structures:

[0024] Preferably, R is any one of the following structures:

[0025] Preferably, 0.2 ≤ X ≤ 0.8.

[0026] Preferably, the preparation process of the polymer shown in formula (I) in step S1 is as follows:

[0027] Mix isatin, a nitrogen-containing heterocyclic monomer containing a carbonyl group, and an aromatic ring-containing monomer, and then carry out a Friedel-Crafts reaction for polycondensation to obtain a terpolymer. The terpolymer undergoes a phosphorylation reaction and a hydrolysis reaction to introduce an organic phosphonic acid group, thereby obtaining the polymer shown in formula (I).

[0028] More preferably, the nitrogen-containing heterocyclic monomer containing a carbonyl group is at least one of N-methylpiperidone, 4-imidazolecarboxaldehyde, or quinuclidone.

[0029] More preferably, the aromatic ring-containing monomer is at least one of biphenyl, 2,2'-dihydroxybiphenyl, p-terphenyl, m-terphenyl, o-terphenyl, fluorene, N-ethylcarbazole or dibenzothiophene.

[0030] More preferably, a solvent is further added during the mixing process; the solvent includes but is not limited to dichloromethane.

[0031] More preferably, the molar ratio of the sum of the amounts of isatin and the nitrogen-containing heterocyclic monomer containing a carbonyl group to the aromatic ring-containing monomer is (1.0 to 1.5):1.

[0032] More preferably, the molar ratio of the nitrogen-containing heterocyclic monomer containing a carbonyl group to isatin is 1:(1 to 4).

[0033] More preferably, the Friedel-Crafts reaction is carried out in the presence of an organic strong acid catalyst; the organic strong acid catalyst includes trifluoroacetic acid and trifluoromethanesulfonic acid with a molar ratio of 1:(1 to 20). The molar ratio of the aromatic ring-containing monomer to the organic strong acid catalyst is 1:(1 to 30).

[0034] More preferably, the reaction temperature of the Friedel-Crafts reaction is 0 to 5 °C, and the reaction time is 5 to 10 h.

[0035] More preferably, after the Friedel-Crafts reaction and before the phosphorylation reaction, there are also steps of sedimentation, washing and drying.

[0036] Further preferably, the reagent used for sedimentation is a poor solvent. The poor solvent includes but is not limited to at least one of water, methanol, ethanol or n-propanol.

[0037] Further preferably, the detergents for washing are water and ethanol.

[0038] Further preferably, the drying temperature is 60 to 100 °C, and the time is 12 to 48 h.

[0039] More preferably, the specific process of the phosphorylation reaction is: adding the terpolymer into an organic solvent and carrying out a phosphorylation reaction with a phosphorylation reagent under a catalyst.

[0040] Further preferably, the organic solvent includes but is not limited to N-methylpyrrolidone. The concentration of the terpolymer in the organic solvent is preferably 0.01 to 0.1 g / mL.

[0041] Further preferably, the phosphorylation reagent includes but is not limited to phosphorus oxychloride; the molar ratio of the terpolymer to the phosphorylation reagent is 1:(1 to 10).

[0042] Further preferably, the catalyst includes but is not limited to pyridine; the molar ratio of the catalyst to the terpolymer is (1-10):1.

[0043] Further preferably, the temperature of the phosphorylation reaction is 0-10°C, and the reaction time is 12-24 h.

[0044] More preferably, the temperature of the hydrolysis reaction is 0-30°C, and the time is 24-48 h.

[0045] More preferably, after the hydrolysis reaction, the steps of washing and drying are further included.

[0046] Further preferably, the washing reagent is at least one of water, methanol or ethanol.

[0047] Further preferably, the drying temperature is 60-100°C, and the time is 12-48 h.

[0048] Preferably, the specific process of mixing the polymer shown in formula (I), the polymer shown in formula (II) and the solvent in step S1 is: first dissolve the polymer shown in formula (I) in the solvent, and then add the polymer shown in formula (II) and mix.

[0049] Preferably, the solvent in step S1 is one of dimethyl sulfoxide, dimethylformamide, dimethylacetamide or N-methylpyrrolidone.

[0050] Preferably, the intrinsic viscosity of the polymer shown in formula (I) is 0.5-3.5 dL / g. The intrinsic viscosity is measured by an Ubbelohde viscometer at 30°C.

[0051] Preferably, the mass ratio of the polymer shown in formula (I) to the polymer shown in formula (II) is (90-95):(5-10).

[0052] Within this mass ratio range, the proton conductivity and peak power density of the obtained composite high-temperature proton exchange membrane are higher.

[0053] Preferably, the number average molecular weight of the polymer shown in formula (II) in step S1 is 600-100,000.

[0054] Preferably, the thickness of the composite film in step S1 is 10-30 μm.

[0055] Preferably, the mass ratio of borax to alkali in the alkali solution of borax in step S2 is (1-4):1.

[0056] Preferably, the borax concentration in the alkali solution of borax in step S2 is 0.1-8 wt%.

[0057] Preferably, the soaking time in step S2 is 5 to 24 h, and the temperature is 30 to 50 °C.

[0058] Preferably, the cleaning agent used for cleaning in step S2 is at least one of water and ethanol.

[0059] Preferably, the drying in step S2 is vacuum drying, and the drying temperature is 50 to 100 °C.

[0060] Preferably, the process of adsorbing phosphoric acid in step S2 is as follows: soaking the dried composite film in a phosphoric acid solution with a concentration of 80 to 90 wt%, maintaining it at 90 to 110 °C for 8 to 16 h, taking it out, and placing it at room temperature (for example, 20 to 30 °C) for 8 to 16 h.

[0061] A high-temperature proton exchange membrane is prepared by the above preparation method.

[0062] The application of the above high-temperature proton exchange membrane in the preparation of high-temperature fuel cells is also within the protection scope of the present invention.

[0063] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0064] The composite high-temperature proton exchange membrane prepared by the preparation method of the present invention still maintains good proton conductivity / high proton conductivity, high peak power density, high tensile strength, and high phosphoric acid retention rate (that is, phosphoric acid is not easily lost) under the condition of low phosphoric acid adsorption amount. Description of the Drawings

[0065] Figure 1 It is a comparison chart of the proton conductivities of the high-temperature proton exchange membranes of Examples 1 to 3 and Comparative Example 1.

[0066] Figure 2 It is a thermogravimetric differential curve chart of the high-temperature proton exchange membrane of Example 1.

[0067] Figure 3 It is a test result chart of the oxidation stability performance of the high-temperature proton exchange membranes of Examples 1 to 3.

[0068] Figure 4 It is a life data chart of the high-temperature proton exchange membrane of Example 2. Detailed Embodiments

[0069] In order to describe the technical solution of the present invention more clearly and completely, the following further details the present invention through specific examples. It should be understood that the specific examples described herein are only used to explain the present invention and are not used to limit the present invention, and various changes can be made within the scope defined by the claims of the present invention.

[0070] Synthesis Example 1

[0071] This synthesis example provides a method for preparing a phosphonic acid-based copolymer, which includes the following steps:

[0072] a) Add p-terphenyl (14.6 mmol), N-methyl-4-piperidone (6.44 mmol), isatin (9.66 mmol) and 14 mL of anhydrous dichloromethane into the reaction flask in sequence. Stir mechanically at 25 °C for 1 h and at 0 °C for 0.5 h. While maintaining the condition of 0 °C, add trifluoroacetic acid (1 mL) and trifluoromethanesulfonic acid (17 mL) dropwise into the flask in sequence. After the addition is completed, continue stirring for 6 h until the solution viscosity increases to obtain a viscous liquid. Pour the viscous liquid into 80 mL of deionized water for sedimentation to obtain a fibrous product. The product is washed repeatedly with a large amount of deionized water and ethanol, and then placed in an oven at 80 °C for drying for 12 h to obtain a terpolymer (P1).

[0073] b) Take the terpolymer P1 (1.0 g) and dissolve it in N-methylpyrrolidone (30 mL). Stir at 80 °C until completely dissolved. At 0 °C, add POCl3 (6 mmol) and pyridine (6 mmol) dropwise into the flask. After reacting for 12 h, the reaction ends. Then add 60 mL of deionized water dropwise into the flask, and then pour the mixed solution into 400 mL of deionized water in total. Stir for 3 days, and then separate the reactant from the water. Wash the product with a large amount of deionized water and ethanol, and place it in an oven at 80 °C for drying to obtain the phosphonic acid-based copolymer.

[0074] The method for preparing the phosphonic acid-based copolymer in this synthesis example refers to the prior art, such as "Intermolecular Acid-Base-Pairs Containing Poly(p-Terphenyl-co-Isatin Piperidinium) for High Temperature Proton Exchange Membrane Fuel Cells". That is, the preparation of the phosphonic acid-based copolymer belongs to the prior art, and the successful synthesis of the phosphonic acid-based copolymer is verified by a nuclear magnetic resonance spectrometer.

[0075] The intrinsic viscosity of the phosphonic acid-based copolymer obtained in this synthesis example measured by an Ubbelohde viscometer is 0.701 dL / g at 30 °C, and its structure is as follows:

[0076]

[0077] Example 1

[0078] This example provides a method for preparing a composite high-temperature proton exchange membrane, which includes the following steps:

[0079] 1) The phosphonic acid copolymer (1 g) was dissolved in DMSO and stirred at 80 °C until completely dissolved. Then, polyethylene glycol with a number-average molecular weight of 600 (0.053 g) was added and stirred at 80 °C for 12 h until well mixed to obtain a casting solution. The casting solution was poured onto a glass plate to form a film, which was dried at 70 °C to obtain a composite film with a thickness of 25 μm.

[0080] 2) Borax and sodium hydroxide (mass ratio 2:1) were added to a mixed solution of methanol and deionized water (volume ratio 19:1) and stirred until completely dissolved to obtain an alkaline solution of borax. The composite film was immersed in the alkaline solution of borax and stirred at 40 °C for 12 h. The composite film was taken out and the residual solvent on the film surface was washed with a large amount of deionized water and ethanol, and then dried in a vacuum drying oven at 100 °C until the film weight no longer changed.

[0081] 3) The composite film was soaked in 85 wt% phosphoric acid solution and placed in an oven at 100 °C for 12 h. Subsequently, the composite film was taken out and placed in a room temperature environment for 12 h to obtain a composite high-temperature proton exchange membrane.

[0082] Example 2

[0083] This example provides a method for preparing a composite high-temperature proton exchange membrane, which is different from Example 1 in that: in step 1), the amount of polyethylene glycol used is 0.111 g.

[0084] Example 3

[0085] This example provides a method for preparing a composite high-temperature proton exchange membrane, which is different from Example 1 in that: in step 1), the amount of polyethylene glycol used is 0.176 g.

[0086] Example 4

[0087] This example provides a method for preparing a composite high-temperature proton exchange membrane, which is different from Example 3 in that: in step 1), polyethylene oxide with a number-average molecular weight of 100,000 is selected to replace polyethylene glycol with a number-average molecular weight of 600.

[0088] Comparative Example 1

[0089] This comparative example provides a method for preparing a high-temperature proton exchange membrane, including the following steps:

[0090] 1) Weigh 1.0 g of phosphonic acid copolymer and dissolve it in 25 mL of dimethyl sulfoxide, and stir at 80 °C for 12 h until completely dissolved to obtain a casting solution. The casting solution was poured onto a glass plate to form a film, which was dried at 70 °C to obtain a film with a thickness of 25 μm.

[0091] 2) Place the film in a 85 wt% phosphoric acid solution and keep it in an oven at 100 °C for 12 h. Then take out the film and keep it at room temperature for 12 h to obtain a high-temperature proton exchange membrane.

[0092] Comparative Example 2

[0093] This comparative example provides a method for preparing a high-temperature proton exchange membrane, which is different from Example 3 in that: in step 1), polyethylene oxide with a number average molecular weight of 600,000 is used instead of polyethylene glycol with a number average molecular weight of 600.

[0094] Performance Test

[0095] Take the high-temperature proton exchange membranes of Examples 1-4 and Comparative Examples 1-2 and prepare them into membrane electrodes by a three-in-one method, and then assemble them in a battery fixture for polarization curve testing. The results are shown in Table 1.

[0096] Table 1

[0097]

[0098] In Table 1, " / " indicates that the test was not conducted.

[0099] The phosphoric acid adsorption amounts of the composite high-temperature proton exchange membranes of Examples 1-4 are all below 58%, the volume swelling rates are all below 42%, the tensile strengths are all above 51 MPa, the phosphoric acid retention rates are all above 78%, and the proton conductivities are all above 27.70 mScm -1 above, indicating that the composite high-temperature proton exchange membrane of the present invention still maintains good proton conductivity under the condition of low phosphoric acid adsorption amount, and has good mechanical properties and high phosphoric acid retention rate, and phosphoric acid is not easily lost. In addition, the peak power densities of the high composite temperature proton exchange membranes of Examples 1-3 are above 400 mWcm -2 above, indicating that the composite high-temperature proton exchange membrane of the present invention has good battery performance.

[0100] Comparing Examples 1 to 3, it can be seen that as the amount of polyethylene glycol increases, the phosphoric acid adsorption amount of the high-temperature proton exchange membrane first increases and then decreases, the volume swelling rate increases, the tensile strength first increases and then decreases, the phosphoric acid retention rate first increases and then decreases, the proton conductivity first increases and then decreases, and the peak power density first increases and then decreases. The reason is that although the cross-linked network formed by polyethylene oxide / polyethylene glycol and borax helps to enhance the interaction between the phosphonic acid copolymer and the phosphoric acid proton conductor. However, when the amount of polyethylene oxide / polyethylene glycol is further increased, its plasticizing effect will have a certain negative impact on the intermolecular force of the phosphonic acid copolymer, reducing the adsorption amount of the phosphoric acid proton conductor and the electrochemical performance and phosphoric acid retention rate of the composite high-temperature proton exchange membrane; therefore, the amount of polyethylene oxide / polyethylene glycol needs to be controlled within a suitable range (relative to Comparative Example 1) to maintain / improve the electrochemical performance of the composite high-temperature proton exchange membrane and increase the phosphoric acid retention rate of the composite high-temperature proton exchange membrane.

[0101] Comparing Examples 1 to 4 and Comparative Example 1, it can be seen that by introducing the cross-linked network formed by polyethylene oxide / polyethylene glycol and borax, the proton conductivity of the high-temperature proton exchange membrane is maintained at a relatively high level (Example 3) / significantly improved (Examples 1, 2, and 4) while the mechanical properties, phosphoric acid retention rate, and peak power density of the high-temperature proton exchange membrane are improved.

[0102] Comparing Examples 3 and 4 and Comparative Example 2, it can be seen that the molecular weight of the selected polyethylene oxide cannot be too large (Comparative Example 2), otherwise the performance cannot be improved and even deteriorates. This is because: when the molecular weight of polyethylene oxide is too large, its compatibility with the phosphonic acid copolymer is poor.

[0103] Figure 1 It is a graph of the proton conductivity data measured for the high-temperature proton exchange membranes of Examples 1 to 3 and Comparative Example 1 under anhydrous conditions at 80 to 180 °C. From Figure 1 it can be seen that in Examples 1 to 2, a high proton transport rate is exhibited under low phosphoric acid adsorption amounts; in Example 3, under low phosphoric acid adsorption amounts, its proton transport rate is comparable to that of Comparative Example 1.

[0104] Figure 2 It is a thermogravimetric differential curve graph of the composite high-temperature proton exchange membrane of Example 1. From Figure 2 it can be seen that for the high-temperature proton exchange membrane of the present invention under a nitrogen atmosphere, the temperature test range is 50 to 800 °C, and the programmed heating rate is 10 °C min -1 , it can be seen that the mass of the composite high-temperature proton exchange membrane does not significantly decrease within 200 °C, indicating that it can remain stable when used as the high-temperature proton exchange membrane of a high-temperature fuel cell. The reason is that borax cross-links with polyethylene glycol / polyethylene oxide to form a cross-linked network, and this cross-linked network can make the molecular chains of polyethylene glycol / polyethylene oxide exist stably.

[0105] Figure 3 It is the graph of the oxidation stability performance results of the composite high-temperature proton exchange membranes of Examples 1 to 3. From Figure 3 it can be seen that the composite high-temperature proton exchange membrane of the present invention has excellent antioxidant stability performance, and the battery assembled with this membrane has good stability during actual operation.

[0106] Figure 4 It is the graph of the life data of the composite high-temperature proton exchange membrane of Example 2. From Figure 4 it can be seen that the high-temperature proton exchange membrane of the present invention has no obvious attenuation of the battery voltage within 220 hours under a constant current load of 140 °C and 200 mA cm -2 , indicating that the composite high-temperature proton exchange membrane of the present invention still has a high phosphoric acid retention rate under low phosphoric acid adsorption conditions, so that there is no obvious attenuation of the voltage during long-term operation.

[0107] Obviously, the above-mentioned embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made on the basis of the above description. It is not necessary and impossible to enumerate all the implementation manners here. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A method for preparing a composite high-temperature proton exchange membrane, characterized in that: The steps include: S1. The polymer represented by formula (Ⅰ), the polymer represented by formula (Ⅱ) and a solvent are mixed to obtain a casting solution, cast, and dried to obtain a composite film; S2. The composite film obtained in step S1 is immersed in an alkaline solution of borax, washed, dried, and then adsorbed with phosphoric acid to obtain the composite high-temperature proton exchange membrane; Formula (I), Formula (II); In formula (I), 0<X<1; Ar is a structure containing an aromatic ring; R is a structure containing a cyclic tertiary amine; In step S1, the mass ratio of the polymer represented by formula (I) to the polymer represented by formula (II) is (90-95):(5-10); The number average molecular weight of the polymer represented by formula (II) is 600-100,000.

2. The preparation method according to claim 1, characterized in that: The Ar is any one of the following structures: , , , or .

3. The preparation method according to claim 1, characterized in that: The R is any one of the following structures: , or .

4. The preparation method according to claim 1, characterized in that: 0.2≤X≤0.8。 5. The preparation method according to claim 1, characterized in that: The preparation process of the polymer represented by formula (I) in step S1 is as follows: Indigo carmine, a carbonyl-containing nitrogen-containing heterocyclic monomer and an aromatic ring-containing monomer are mixed and then subjected to Friedel-Crafts polycondensation to obtain a terpolymer. The terpolymer undergoes phosphorylation and hydrolysis to introduce an organic phosphonic acid group, thereby obtaining the polymer represented by formula (I).

6. The preparation method according to claim 1, characterized in that: The solvent in step S1 is one of dimethyl sulfoxide, dimethylformamide, dimethylacetamide or N-methylpyrrolidone.

7. The preparation method according to claim 1, characterized in that: The soaking time in step S2 is 5 to 24 hours, and the temperature is 30 to 50°C.

8. A composite high temperature proton exchange membrane, characterized in that: It is prepared by the preparation method described in any one of claims 1 to 7.

9. Use of the composite high-temperature proton exchange membrane according to claim 8 in the preparation of a high-temperature fuel cell.

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