Water-soluble phosphonated polybenzimidazole polymer and preparation method thereof

Abstract

The invention discloses a water-soluble phosphonated polybenzimidazole polymer and a preparation method thereof, and particularly, under the protection of nitrogen flow, 3, 3 '-diaminobenzidine and diphosphonic acid substituted aromatic dicarboxylic acid react for 6-30 hours at 180-250 DEG C by taking polyphosphoric acid as a medium, and the phosphonated polybenzimidazole polymer is obtained through polycondensation. The phosphonated polybenzimidazole polymer disclosed by the invention has good solubility in water under an alkaline condition, can be used as a solvent in subsequent processing, has the characteristics of no pollution and environmental protection, is easy to recover and has a wide application prospect.

Description

Technical Field

[0001] The invention relates to the field of high-temperature fuel cell proton exchange membranes, and in particular to a water-soluble phosphonated polybenzimidazole polymer, a preparation method thereof, and application thereof in high-temperature fuel cell proton exchange membranes. Background Art

[0002] At present, the proton exchange membrane widely used in high-temperature proton exchange membrane fuel cells is a PBI (polybenzimidazole) type proton exchange membrane. The PBI membrane was first introduced to the market by the American Hoechst Celanese Company. Since the membrane must be mixed with inorganic phosphoric acid and relies on inorganic phosphoric acid to conduct protons, its biggest disadvantage is the loss of inorganic phosphoric acid. Since water is generated when the fuel cell is working, and the generated water is discharged from the membrane, this will cause the inorganic phosphoric acid to be lost along with the removal of the generated water, thereby causing the proton conductivity of the membrane to decrease, and causing the battery performance to decay, and also shortening the stable service life of the fuel cell.

[0003] Phosphonic acid functionalization is an effective way to improve the proton conductivity of PBI proton exchange membrane, reduce the adsorption level of inorganic phosphate, reduce the loss of inorganic phosphate and improve the mechanical strength of proton exchange membrane.

[0004] At present, the methods of phosphonic acid functionalization of polybenzimidazole that have been publicly reported are as follows:

[0005] CN114479081A discloses “a phosphonic acid functionalized polybenzimidazole and its preparation method and application”. This method belongs to the model of front-end modification and post-polymerization.

[0006] The disadvantages of this method are: the number of introduced phosphonic acid functional groups is low and it is not soluble in water. The membrane preparation process uses organic solvents, which are highly polluting and costly.

[0007] Johnson, FE et al., "Synthesis and Mechanism of PBI Phosphonate, Poly[2,2'-(-m-phenylene)-5,5'-Bibenzimidazole Phosphonate Ester], and its Polyphosphonic Acid Derivatives", Macromolecules, Vol. 43, No. 8, 2010, pp. 3634-3651, reported a technical solution for introducing phosphonic acid groups into the PBI skeleton structure.

[0008] The disadvantages of this method are that it is a post-modification method to introduce phosphonic acid groups, the amount of reagents used is large, and due to the solubility limitation of PBI, the preparation amount is small, the operation is complicated, and the number of introduced phosphonic acid groups needs to be titrated later. In addition, the membrane preparation process of this scheme still uses organic solvents, which is highly polluting. In addition, acid hydrolysis is not required after the membrane is prepared, the process is complicated, and large-scale production is not possible.

[0009] Therefore, there is an urgent need to develop a method for preparing phosphonic acid functionalized polybenzimidazole with simple process, low pollution and low cost. Summary of the invention

[0010] The purpose of the present invention is to provide a water-soluble phosphonated polybenzimidazole polymer and a preparation method thereof, and the method is suitable for large-scale batch preparation.

[0011] In a first aspect of the present invention, a method for preparing a polybenzimidazole polymer is provided, characterized in that the method comprises:

[0012] In an inert atmosphere, in the presence of an acid, the tetraamine compound represented by Formula I and the aromatic dicarboxylic acid substituted with a bisphosphonic acid group represented by Formula II are polymerized to prepare a polybenzimidazole polymer represented by Formula III:

[0013]

[0014] in:

[0015] n=2-10000; preferably, n=50-2000;

[0016] Selected from the following group: C6-C 10 Aryl, bicyclic (C6-C 10 Aryl), or (C6-C 10 Aryl)-R-(C6-C 10 aryl); wherein, said R is selected from the following group: O, S, NH, C(O), S(O)2, substituted or unsubstituted C1-C6 alkylene, substituted or unsubstituted C2-C6 alkenylene;

[0017] Selected from the group consisting of: substituted or unsubstituted C6-C 10 aryl, substituted or unsubstituted 5-12 membered heteroaryl;

[0018] Furthermore, the substitution in the substituted or unsubstituted group refers to that one or more hydrogen atoms on the group are replaced by a substituent selected from the group consisting of halogen, phenyl, and 5-7 membered heteroaryl.

[0019] In some embodiments, the method includes one or more of the following features:

[0020] (1) The molar ratio of the compound of formula I to the compound of formula II is 1:0.6-1.5;

[0021] (2) The acid is selected from the group consisting of polyphosphoric acid;

[0022] (3) The acid is 5-100 times the total mass of the compound of formula I and the compound of formula II; preferably, 10-80 times; more preferably, 15-50 times;

[0023] (4) The polymerization is carried out at 150°C-300°C; preferably at 180-250°C.

[0024] In some embodiments, the compound of formula I is selected from the following group:

[0025]

[0026] In some embodiments, the compound of formula II is:

[0027]

[0028] In another preferred embodiment, the compound of formula II is selected from the following group:

[0029]

[0030] In some embodiments, the method comprises the steps of:

[0031] (1) adding acid into a reaction kettle and heating in an inert atmosphere;

[0032] (2) Adding the compound of formula I and the compound of formula II into a reaction kettle, and performing a polymerization reaction under an inert atmosphere to obtain a polybenzimidazole polymer.

[0033] In some embodiments,

[0034] The heating temperature in step (2) is 50-250°C, preferably 100-200°C

[0035] The reaction temperature of step (2) is 150°C-300°C, preferably 180-250°C.

[0036] In some embodiments, the steps are also included:

[0037] (3) washing the polybenzimidazole polymer obtained in step (2), crushing it, washing it again, filtering it, and drying it to obtain the polybenzimidazole polymer.

[0038] In a second aspect of the present invention, a polybenzimidazole polymer is provided, wherein the polybenzimidazole polymer has a structure selected from the following group:

[0039]

[0040] Wherein, n=2-10000; preferably, n=50-2000;

[0041] R is selected from the group consisting of O, S, NH, C(O), S(O)2, substituted or unsubstituted C1-C6 alkylene, substituted or unsubstituted C2-C6 alkenylene;

[0042] R 1 Select from the following group:

[0043]

[0044] In the third aspect of the present invention, a high-temperature proton exchange membrane for a fuel cell is provided, wherein the high-temperature proton exchange membrane is prepared using the polybenzimidazole polymer as described in the second aspect of the present invention.

[0045] In some embodiments, the method comprises the steps of:

[0046] (I) preparing an aqueous solution of the polybenzimidazole polymer according to the second aspect of the present invention and a base;

[0047] (II) casting the aqueous solution onto a glass plate, drying it, and peeling it off to obtain a polymer film;

[0048] (III) Soaking the polymer membrane in phosphoric acid to obtain the fuel cell high temperature proton exchange membrane.

[0049] In some embodiments, the method includes one or more of the following features:

[0050] In step (I), the base is selected from the group consisting of LiOH, NaOH, KOH, and CsOH; the molar ratio of the polybenzimidazole polymer to the base is 1:0.5-1:4; the content of the polybenzimidazole polymer in the aqueous solution is 1%-10% by weight;

[0051] In step (II), the drying is carried out at 50-100° C. and the drying time is 2-10 hours;

[0052] In step (III), the phosphoric acid is a 50-85% by weight phosphoric acid aqueous solution.

[0053] It should be understood that within the scope of the present invention, the above-mentioned technical features of the present invention and the technical features specifically described below (such as embodiments) can be combined with each other to form a new or preferred technical solution. Due to space limitations, they will not be described one by one here. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 This is the hydrogen spectrum of 2,5-diphosphonoterephthalic acid (deuterated DMSO).

[0055] Figure 2 This is the phosphorus spectrum of 2,5-diphosphonoterephthalic acid (deuterated DMSO).

[0056] Figure 3 This is the hydrogen spectrum of 4,6-diphosphonoisophthalic acid (deuterated DMSO).

[0057] Figure 4 This is the phosphorus spectrum of 4,6-diphosphonoisophthalic acid (deuterated DMSO).

[0058] Figure 5 This is the hydrogen spectrum of polymer 2 (D2O+NaOH).

[0059] Figure 6 This is the phosphorus spectrum of polymer 2 (D2O+NaOH).

[0060] Figure 7 Shown is a diagram for a polymer sample.

[0061] Figure 8 This is a diagram of the membrane preparation process and recycling process of water-soluble phosphonated polybenzimidazole polymer.

[0062] Fig. 9 Demonstration diagram of recycling of water-soluble phosphonated polybenzimidazole polymer membrane.

[0063] Fig.10 This is the TGA display of polymer 1.

[0064] Fig.11 This is the TGA display diagram of polymer 3.

[0065] The main advantages of the present invention are:

[0066] (1) The present invention prepares the phosphonic acid functionalized polybenzimidazole polymer by monomer polymerization, which is simpler in steps and convenient in handling than the method of introducing phosphonic acid by post-grafting, and is suitable for large-scale batch preparation.

[0067] (2) The phosphonic acid functionalized polybenzimidazole polymer prepared by the present invention has a certain structure and a certain phosphonic acid content.

[0068] (3) The phosphonic acid functionalized polybenzimidazole polymer prepared by the present invention can be dissolved in water under alkaline conditions, so that its subsequent film-making process is convenient and simple, green and pollution-free, environmentally friendly, low-cost, and suitable for large-scale batch production.

[0069] (4) The phosphonic acid functionalized polybenzimidazole polymer prepared by the present invention is soluble in water under alkaline conditions, but insoluble in water under neutral or acidic conditions, which makes its use and recycling process particularly simple, with low recycling cost (only water and alkali are needed for recycling), and meets the conditions for recycling and cyclic use.

[0070] (5) The introduction of phosphonic acid groups increases the hydrogen bonding between molecular chains and the mechanical strength of proton exchange membrane materials. It also increases the hydrogen bonding between inorganic phosphoric acid and can slow down the loss rate of inorganic phosphoric acid in phosphoric acid-doped proton exchange membranes.

[0071] (6) The introduction of phosphonic acid groups increases the number of proton conduction sites. When the same proton transfer rate is required, the adsorption amount of inorganic phosphoric acid can be reduced, thereby improving the mechanical strength of the phosphoric acid-doped proton exchange membrane. DETAILED DESCRIPTION

[0072] After long-term and in-depth research, the inventors found that high-proton conductivity polybenzimidazole polymers can be prepared by high-temperature polymerization of tetraamine compounds and aromatic dicarboxylic acids substituted with bisphosphonic acid groups, and the polymerization method is milder than the solid-phase polymerization method of similar products. The phosphonated polybenzimidazole polymer of the present invention has good solubility in water under alkaline conditions, and water can be used as a solvent in subsequent processing. It has pollution-free and environmentally friendly characteristics, and is easy to recycle, has a wide range of application prospects, and is very suitable for preparing proton exchange membranes for fuel cells. Based on the above findings, the inventors have completed the present invention.

[0073] Preparation of polybenzimidazole polymers by solution polymerization

[0074] The present invention provides a method for preparing a polybenzimidazole polymer by solution polymerization, the method comprising:

[0075] In an inert atmosphere, in the presence of an acid, a tetraamine compound and an aromatic dicarboxylic acid substituted with a bisphosphonic acid group are polymerized to prepare a polybenzimidazole polymer.

[0076] The tetraamine compound is selected from the following group:

[0077]

[0078] The bisphosphonic acid-substituted aromatic dicarboxylic acid is:

[0079] The acid is polyphosphoric acid.

[0080] The specific operation method of the polymerization is:

[0081] The first step is to add acid into the reactor, heat it to about 100°C, start mechanical stirring, and increase the nitrogen flow to deoxygenate.

[0082] In the second step, when the acid is heated to 150°C, the tetraamine compound is added. After it is completely dissolved, the aromatic dicarboxylic acid substituted with a bisphosphonic acid group is added at a molar ratio of 1:1, and the temperature is started to rise to above 150°C. The reaction is carried out at this temperature for 14 hours. At this time, the stirring speed drops significantly, stirring becomes difficult, and the reaction is stopped.

[0083] Preferably, the nitrogen flow rate is 1%-800% of the volume of the reactor per minute, more preferably 100%-500%.

[0084] Preferably, the amount of the acid is 5-100 times the total mass of the tetraamine compound and the bisphosphonic acid-substituted aromatic dicarboxylic acid; more preferably, 10-80 times; more preferably, 15-50 times.

[0085] Preferably, the reaction temperature of the second step is 150-300°C, more preferably 160-280°C, more preferably 180-250°C.

[0086] Preferably, the reaction time of the second step is 6-30 hours, more preferably 12-28 hours, and more preferably 15-25 hours.

[0087] The polymer is suitable for preparing a high-temperature fuel cell proton exchange membrane, in particular a high-temperature fuel cell proton exchange membrane. In a preferred embodiment, the preparation method of the high-temperature proton exchange membrane is as follows:

[0088] Under the protection of inert gas, the prepared polymer is dissolved in an aqueous solution of alkali to prepare a solution with a certain solid content, and the insoluble matter is filtered to remove to obtain a filtrate, the filtrate is degassed, and then a membrane is prepared by a casting method to obtain a high-temperature proton exchange membrane.

[0089] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods in the following examples without specifying specific conditions are usually based on conventional conditions or the conditions recommended by the manufacturer. Unless otherwise stated, percentages and parts are calculated by weight.

[0090] Example 1

[0091] Preparation of polymer 1:

[0092]

[0093] Under nitrogen protection, polyphosphoric acid (160g) was first added to a three-necked reaction bottle equipped with mechanical stirring. When heated to about 100°C, mechanical stirring was started and nitrogen flow was increased for deoxygenation. When heated to 150°C, 3,3'-diaminobenzidine (3.2141g, 15mmol) was added. After it was completely dissolved, 2,5-diphosphonic acid terephthalic acid (4.8914g, 15mmol) was added and the temperature was raised to 220°C. The reaction was carried out at this temperature for 14 hours. At this time, the stirring speed dropped seriously and stirring was difficult, so the reaction was stopped. The reaction solution was poured into deionized water to precipitate a filamentous solid. When the solid was soaked and washed in deionized water until the water was weakly acidic, the filamentous product was crushed into powder with a pulverizer, and the phosphonated polybenzimidazole polymer was obtained by continued soaking and washing in deionized water until the water was neutral. Then, the phosphonated polybenzimidazole polymer was obtained by filtration and drying. Intrinsic viscosity test (30°C) [η] = 2.09 (dL / g) [Test conditions: dissolve the polymer in 98% concentrated sulfuric acid to make a solution with a concentration of 0.5 g / mL]. Solubility test: 150 mg (0.32 mmol) of polymer and 64 mg (1.6 mmol) of sodium hydroxide are dissolved in 5 mL of deionized water and heated to 80°C. After half an hour, the polymer is completely dissolved. Stop heating and cool to room temperature. The solution has moderate fluidity.

[0094] Example 2

[0095] Preparation of polymer 1:

[0096]

[0097] Under nitrogen protection, polyphosphoric acid (160g) was first added to a three-necked reaction bottle equipped with mechanical stirring. When heated to about 100°C, mechanical stirring was started and nitrogen flow was increased for deoxygenation. When heated to 150°C, 3,3'-diaminobenzidine (3.2141g, 15mmol) was added. After it was completely dissolved, 2,5-diphosphonic acid terephthalic acid (4.8914g, 15mmol) was added and the temperature was raised to 210°C. The reaction was carried out at this temperature for 14 hours. At this time, the stirring speed dropped significantly and stirring was difficult, so the reaction was stopped. The reaction solution was poured into deionized water to precipitate a filamentous solid. When the solid was soaked and washed in deionized water until the water was weakly acidic, the filamentous product was crushed into powder with a pulverizer, and the phosphonated polybenzimidazole polymer was obtained by continued soaking and washing in deionized water until the water was neutral. Then, the phosphonated polybenzimidazole polymer was obtained by filtration and drying. Intrinsic viscosity test (30°C) [η] = 1.84 (dL / g) [Test conditions: dissolve the polymer in 98% concentrated sulfuric acid to make a solution with a concentration of 0.5 g / mL]. Solubility test: 150 mg (0.32 mmol) of polymer and 64 mg (1.6 mmol) of sodium hydroxide are dissolved in 5 mL of deionized water and heated to 80°C. After half an hour, the polymer is completely dissolved. Stop heating and cool to room temperature. The solution has moderate fluidity.

[0098] Example 3

[0099] Preparation of polymer 1:

[0100]

[0101] Under nitrogen protection, polyphosphoric acid (160g) was first added to a three-necked reaction bottle equipped with mechanical stirring. When heated to about 100°C, mechanical stirring was started and nitrogen flow was increased for deoxygenation. When heated to 150°C, 3,3'-diaminobenzidine (3.2141g, 15mmol) was added. After it was completely dissolved, 2,5-diphosphonic acid terephthalic acid (4.8914g, 15mmol) was added and the temperature was raised to 200°C. The reaction was carried out at this temperature for 16 hours. At this time, the stirring speed dropped significantly and the reaction was stopped. The reaction solution was poured into deionized water to precipitate a filamentous solid. When the filamentous solid was soaked and washed in deionized water until the water was weakly acidic, the filamentous product was crushed into powder with a pulverizer, and the filamentous product was continued to be soaked and washed in deionized water until the water was neutral, and then filtered and dried to obtain a phosphonated polybenzimidazole polymer. Intrinsic viscosity test (30°C) [η] = 1.71 (dL / g) [Test conditions: dissolve the polymer in 98% concentrated sulfuric acid to make a solution with a concentration of 0.5 g / mL]. Solubility test: 150 mg (0.32 mmol) of polymer and 64 mg (1.6 mmol) of sodium hydroxide are dissolved in 5 mL of deionized water and heated to 80°C. After half an hour, the polymer is completely dissolved. Stop heating and cool to room temperature. The solution has moderate fluidity.

[0102] Example 4

[0103] Preparation of polymer 2:

[0104]

[0105] Under nitrogen protection, polyphosphoric acid (160g) was first added to a three-necked reaction bottle equipped with mechanical stirring. When heated to about 100°C, mechanical stirring was started and nitrogen flow was increased for deoxygenation. When heated to 150°C, 3,3'-diaminobenzidine (3.2141g, 15mmol) was added. After it was completely dissolved, 4,6-diphosphonoisophthalic acid (4.8914g, 15mmol) was added and the temperature was raised to 220°C. The reaction was continued at this temperature for 20 hours. At this time, the stirring speed decreased a little and the reaction was stopped. The reaction solution was poured into deionized water to precipitate a filamentous solid. When the filamentous product was soaked and washed in deionized water until the water was weakly acidic, it was crushed into powder with a pulverizer. It was continued to be soaked and washed in deionized water until the water was neutral, and then filtered and dried to obtain a phosphonated polybenzimidazole polymer. Intrinsic viscosity test (30°C) [η] = 1.25 (dL / g) [Test conditions: dissolve the polymer in 98% concentrated sulfuric acid to make a solution with a concentration of 0.5g / mL]. Solubility test: 150mg (0.32mmol) of polymer and 64mg (1.6mmol) of sodium hydroxide are dissolved in 5mL of deionized water, heated to 80°C, and after half an hour, the polymer is completely dissolved. Stop heating and cool to room temperature. The solution has low fluidity.

[0106] Example 5

[0107] Preparation of polymer 3:

[0108]

[0109] Where x:y=1:1

[0110] Under nitrogen protection, polyphosphoric acid (160g) was first added to a three-necked reaction bottle equipped with mechanical stirring. When heated to about 100°C, mechanical stirring was started and nitrogen flow was increased for deoxygenation. When heated to 150°C, 3,3'-diaminobenzidine (3.2141g, 15mmol) was added. After it was completely dissolved, 4,6-diphosphonoisophthalic acid (2.4457g, 7.5mmol) and 2,5-diphosphonoterephthalic acid (2.4457g, 7.5mmol) were added, and the temperature was raised to 220°C. The reaction was carried out at this temperature for 18 hours. At this time, the stirring speed dropped significantly and the reaction was stopped. The reaction solution was poured into deionized water to precipitate a filamentous solid. When the filamentous solid was soaked and washed in deionized water until the water was weakly acidic, the filamentous product was crushed into powder with a pulverizer, and the phosphonated polybenzimidazole polymer was obtained by soaking and washing in deionized water until the water was neutral. Then, the phosphonated polybenzimidazole polymer was obtained by filtering and drying. Intrinsic viscosity test (30°C) [η] = 1.58 (dL / g) [Test conditions: dissolve the polymer in 98% concentrated sulfuric acid to make a solution with a concentration of 0.5g / mL]. Solubility test: 150mg (0.32mmol) polymer and 64mg (1.6mmol) sodium hydroxide are dissolved in 5mL deionized water and heated to 80°C. After half an hour, the polymer is completely dissolved. Stop heating and cool to room temperature. The solution fluidity is moderate.

[0111] All documents mentioned in the present invention are cited as references in this application, just as each document is cited as reference individually. In addition, it should be understood that after reading the above teachings of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A method for preparing a polybenzimidazole polymer, characterized in that: The method includes: In an inert atmosphere, in the presence of an acid, the tetraamine compound represented by Formula I and the aromatic dicarboxylic acid substituted with a bisphosphonic acid group represented by Formula II are polymerized to prepare a polybenzimidazole polymer represented by Formula III: in: n=2-10000; preferably, n=50-2000; Selected from the following group: C6-C 10 Aryl, bicyclic (C6-C 10 Aryl), or (C6-C 10 Aryl)-R-(C6-C 10 aryl); wherein, said R is selected from the following group: O, S, NH, C(O), S(O)2, substituted or unsubstituted C1-C6 alkylene, substituted or unsubstituted C2-C6 alkenylene; Selected from the group consisting of: substituted or unsubstituted C6-C 10 aryl, substituted or unsubstituted 5-12 membered heteroaryl; Furthermore, the substitution in the substituted or unsubstituted group refers to that one or more hydrogen atoms on the group are replaced by a substituent selected from the group consisting of halogen, phenyl, and 5-7 membered heteroaryl.

2. The preparation method according to claim 1, characterized in that The method includes one or more of the following features: (1) The molar ratio of the compound of formula I to the compound of formula II is 1:0.6-1.5; (2) The acid is selected from the group consisting of polyphosphoric acid; (3) The acid is 5-100 times the total mass of the compound of formula I and the compound of formula II; preferably, 10-80 times; more preferably, 15-50 times; (4) The polymerization is carried out at 150°C-300°C; preferably at 180-250°C.

3. The preparation method according to claim 1, characterized in that: The compound of formula I is selected from the following group:

4. The preparation method according to claim 1, characterized in that: The compound of formula II is: In another preferred embodiment, the compound of formula II is selected from the following group:

5. The preparation method according to claim 1, characterized in that: The method comprises the steps of: (1) adding acid into a reaction kettle and heating in an inert atmosphere; (2) Adding the compound of formula I and the compound of formula II into a reaction kettle, and performing a polymerization reaction under an inert atmosphere to obtain a polybenzimidazole polymer.

6. The preparation method according to claim 5, characterized in that: The heating temperature in step (2) is 50-250°C, preferably 100-200°C The reaction temperature of step (2) is 150°C-300°C, preferably 180-250°C.

7. The preparation method according to claim 5, characterized in that: Also includes the steps: (3) washing the polybenzimidazole polymer obtained in step (2), crushing it, washing it again, filtering it, and drying it to obtain the polybenzimidazole polymer.

8. A polybenzimidazole polymer, characterized in that: The polybenzimidazole polymer has a structure selected from the following group: Wherein, n=2-10000; preferably, n=50-2000; R is selected from the group consisting of O, S, NH, C(O), S(O)2, substituted or unsubstituted C1-C6 alkylene, substituted or unsubstituted C2-C6 alkenylene; R 1 Select from the following group:

9. A high temperature proton exchange membrane for a fuel cell, characterized in that: The high temperature proton exchange membrane is prepared by using the polybenzimidazole polymer as claimed in claim 8.

10. The method for preparing a fuel cell high temperature proton exchange membrane according to claim 9, characterized in that: Includes steps: (I) preparing an aqueous solution of the polybenzimidazole polymer according to claim 8 and a base; (II) casting the aqueous solution onto a glass plate, drying it, and peeling it off to obtain a polymer film; (III) Soaking the polymer membrane in phosphoric acid to obtain the fuel cell high temperature proton exchange membrane.

11. The preparation method according to claim 10, characterized in that: The method includes one or more of the following features: In step (I), the base is selected from the group consisting of LiOH, NaOH, KOH, and CsOH; the molar ratio of the polybenzimidazole polymer to the base is 1:0.5-1:4; the content of the polybenzimidazole polymer in the aqueous solution is 1%-10% by weight; In step (II), the drying is carried out at 50-100° C. and the drying time is 2-10 hours; In step (III), the phosphoric acid is a 50-85% by weight phosphoric acid aqueous solution.

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