A high temperature resistant hydrogen fuel cell ion exchange membrane and preparation method thereof

Abstract

The invention relates to a high-temperature resistant hydrogen fuel cell ion exchange membrane and a preparation method thereof, belonging to the technical field of fuel cells. The membrane is based on a perfluorosulfonic acid resin and the high-temperature proton exchange stability of the membrane material is improved by introducing a self-made phosphated MOF. The phosphated MOF is a metal framework compound carrier and is a good proton conductor. The proton exchange capacity can be improved by being doped in the perfluorosulfonic acid resin. The membrane has a high specific surface area and is rich in microscopic pores. The phosphating agent loaded in situ by liquid phase conversion has high dispersibility and is anchored by chelation, so it is not easy to be lost in a high-temperature environment and maintains a stable dispersed structure. The phosphorus structure introduced by the phosphating agent constitutes a hydrogen bond network for proton transfer, which greatly improves the high-temperature proton transfer stability of the membrane material.

Description

Technical Field

[0001] The present invention belongs to the technical field of fuel cells, and in particular, relates to a high temperature resistant hydrogen fuel cell ion exchange membrane and a preparation method thereof. Background Art

[0002] A fuel cell is an energy conversion device that can directly and quickly convert the chemical energy in the fuel into electrical energy through an electrochemical reaction. A hydrogen fuel cell uses hydrogen as fuel. The hydrogen is sent to the anode plate of the fuel cell. After the catalyst acts, an electron in the hydrogen atom is separated. The hydrogen ion that has lost the electron passes through the ion exchange membrane and reaches the cathode plate of the fuel cell. However, electrons cannot pass through the ion exchange membrane. They can only reach the cathode plate of the fuel cell through an external circuit, thereby generating current in the external circuit. After the electrons reach the cathode plate, they recombine with oxygen atoms and hydrogen ions to form water. Since the oxygen supplied to the cathode plate can be obtained from the air, as long as hydrogen is continuously supplied to the anode plate, air is supplied to the cathode plate, and the water is taken away in time, electrical energy can be continuously provided.

[0003] The role of ion exchange membrane in hydrogen fuel cells is to conduct protons and block fuels and oxidants. Among them, perfluorosulfonic acid ion exchange membrane has good proton conductivity and physical and chemical properties and is widely used in fuel cells. In the prior art, a certain amount of proton conducting medium, such as ionic liquids, phosphoric acid, etc., is usually doped into the membrane material to improve the proton conductivity of the membrane material. However, the operating temperature of the fuel cell reaches above 120°C, and these proton conduction media are unevenly dispersed and easy to lose, resulting in a decrease in the proton conductivity of the membrane material at high temperatures, which makes it difficult to improve the battery energy efficiency. Summary of the invention

[0004] In order to solve the technical problems mentioned in the background technology, the purpose of the present invention is to provide a high temperature resistant hydrogen fuel cell ion exchange membrane and a preparation method thereof.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A high temperature resistant hydrogen fuel cell ion exchange membrane, formed by casting a phosphated MOF and a perfluorosulfonic acid resin;

[0007] Among them, the phosphated MOF is prepared by the following method:

[0008] Step A1: vinylphosphonic acid, photosensitizer and acetone are mixed, the pH value of the reaction system is adjusted to 4-5 with acetic acid, the temperature is controlled to 5-15° C. in an ice-water bath, the mixture is stirred and irradiated with ultraviolet light, ethylenedithiol is added intermittently, and the total reaction time of ethylenedithiol addition is controlled to be 6-8 hours. After the reaction is completed, acetone is removed by rotary evaporation to obtain a phosphating agent;

[0009] Further, the dosage ratio of ethanedithiol, vinylphosphonic acid, photosensitizer and acetone is 0.1 mol: 0.2 mol: 8-12 mg: 25-35 mL, and under ultraviolet irradiation and initiation of the photosensitizer, ethanedithiol and vinylphosphonic acid are added to form a thioether-containing compound;

[0010] Preferably, the photosensitizer is photoinitiator 784, and the ultraviolet irradiation intensity is 550-700W / m 2 .

[0011] Step A2: The phosphating agent and deionized water are mixed and heated to 80-90°C as a loading liquid, and then zirconium oxychloride octahydrate and fumaric acid are dissolved in dimethylacetamide, and slowly added to the loading liquid under ultrasonic vibration. After the addition is complete, the pressure is increased and the temperature is increased to 120-140°C to continue the reaction for 3-4 hours. After the reaction is completed, centrifugation is performed, and the bottom precipitate is washed and dried to obtain the phosphated MOF;

[0012] Furthermore, the molar ratio of zirconium oxychloride octahydrate, fumaric acid and phosphating agent is 1:0.88-0.95:0.1-0.15, the mass fraction of the phosphating agent in the loading liquid is 4-6%, fumaric acid is a ligand and forms a metal framework compound with zirconium oxychloride octahydrate as a carrier, and the phosphorus-containing thioether structure in the phosphating agent molecule forms a chelating effect and combines with the carrier for doping.

[0013] The high temperature resistant hydrogen fuel cell ion exchange membrane is prepared by the following method:

[0014] Step S1: prepare an alkaline isopropanol aqueous solution with sodium hydroxide, add perfluorosulfonic acid resin to mix, heat and reflux for 2.5-3h, then neutralize with formic acid, add phosphated MOF and mix well to obtain a casting solution;

[0015] Furthermore, the pH value of the alkaline isopropanol aqueous solution is 9-10, and the amount of the phosphated MOF is 0.9-1.1 wt % of the perfluorosulfonic acid resin.

[0016] Step S2: The casting liquid is vacuum-baked, and the material is transferred to a steel belt casting machine for casting into a film, and then immersed in deionized water for cleaning and drying to obtain a high-temperature resistant hydrogen fuel cell ion exchange membrane.

[0017] Furthermore, the solid content of the casting solution after vacuum baking is 13-17wt%.

[0018] Furthermore, during the film casting process, the drying temperature zones are set as: 45-55°C in zone one, 75-90°C in zone two, 60-70°C in zone three, and 50-60°C in zone four.

[0019] Beneficial effects of the present invention:

[0020] The ion exchange membrane disclosed in the present invention uses perfluorosulfonic acid resin as a matrix, and introduces a self-made phosphated MOF to improve the high-temperature proton exchange stability of the membrane material; the phosphated MOF is prepared by the addition of ethanedithiol and vinylphosphonic acid to form a phosphide containing a sulfide structure, namely a phosphating agent, and then through a liquid phase conversion process, fumaric acid is used as a ligand to form a metal framework compound as a carrier with zirconium oxychloride octahydrate, and the chelation effect of the phosphorus-containing sulfide structure in the phosphating agent molecule is combined with the carrier for doping, the metal framework compound itself is a good proton conductor, and the proton exchange capacity can be improved by doping in the perfluorosulfonic acid resin, the metal framework compound has a high specific surface area and is rich in microscopic pores, the phosphating agent loaded in situ by liquid phase conversion has high dispersibility, and is anchored by chelation, is not easy to be lost in a high-temperature environment, and maintains a stable dispersed structure, and the phosphorus structure introduced by the phosphating agent forms a hydrogen bond network for proton transfer, which greatly improves the high-temperature proton transfer stability of the membrane material. DETAILED DESCRIPTION

[0021] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Example 1, preparation of high temperature resistant hydrogen fuel cell ion exchange membrane, the specific implementation process is as follows:

[0023] (1) Preparation of phosphated MOF

[0024] Step A1: Mix vinylphosphonic acid, photosensitizer and acetone, add acetic acid to adjust the pH value of the reaction system to 5, control the temperature at 5°C in an ice water bath, apply mechanical stirring at 90 rpm, and apply 550 W / m 2 Under ultraviolet irradiation, take equal amounts of ethanedithiol and divide them into four parts, add them intermittently for 30 minutes, continue the constant temperature irradiation reaction after complete addition, and control the total reaction time of ethanedithiol addition to be 8 hours. In the above reaction, the photosensitizer uses high-efficiency photoinitiator 784, wherein the amount ratio of ethanedithiol, vinylphosphonic acid, photosensitizer and acetone is 0.1 mol: 0.2 mol: 8 mg: 25 mL. After the reaction is completed, the acetone is removed by rotary evaporation to obtain the phosphating agent.

[0025] Step A2: Take the phosphating agent and add it to deionized water, stir and dissolve it, control the mass fraction of the phosphating agent to be about 6%, heat it to 80°C as the loading liquid, then take zirconium oxychloride octahydrate and fumaric acid, add dimethylacetamide and stir until completely dissolved, apply 28kHz ultrasonic vibration to the loading liquid, slowly add the dissolved solution of zirconium oxychloride octahydrate and fumaric acid, control the addition rate to 1.5mL / min, pressurize the reaction system after complete addition, and heat the reaction system to 120°C to continue the reaction for 4h. In the reaction, the molar ratio of zirconium oxychloride octahydrate, fumaric acid and phosphating agent is 1:0.95:0.1. After the reaction is completed, centrifuge, take the bottom precipitate, wash and dry it, and obtain the phosphated MOF.

[0026] (2) Cast film

[0027] Step S1: Take isopropanol and dilute it to a volume fraction of 60%, add sodium hydroxide to alkalize it to a pH value of 9, prepare an alkaline isopropanol aqueous solution, then add perfluorosulfonic acid resin and stir to dissolve, heat to 80°C and reflux for 3h, then add formic acid to neutralize, and then add 0.9wt% of perfluorosulfonic acid resin and phosphated MOF to mix, wherein the perfluorosulfonic acid resin adopts NR50 type raw material to obtain a casting solution.

[0028] Step S2: vacuum-dry the casting liquid, control the solid content of the drying to 13wt%, and transfer the discharged material to a steel belt casting machine for film casting. During the film casting process, the drying temperature zones are set to: 55°C for zone 1, 90°C for zone 2, 70°C for zone 3, and 60°C for zone 4. Remove the membrane material, immerse it in deionized water for cleaning, and dry it to obtain a high-temperature resistant hydrogen fuel cell ion exchange membrane.

[0029] Example 2, preparation of high temperature resistant hydrogen fuel cell ion exchange membrane, the specific implementation process is as follows:

[0030] (1) Preparation of phosphated MOF

[0031] Step A1: Mix vinylphosphonic acid, photosensitizer and acetone, add acetic acid to adjust the pH value of the reaction system to 4, control the temperature at 15°C in an ice water bath, apply mechanical stirring at 120 rpm, and apply 700 W / m 2 Under ultraviolet irradiation, take equal amounts of ethanedithiol and divide them into four parts, add them intermittently for 20 minutes, continue the constant temperature irradiation reaction after complete addition, and control the total reaction time of ethanedithiol addition to be 6 hours. In the above reaction, the photosensitizer uses high-efficiency photoinitiator 784, wherein the amount ratio of ethanedithiol, vinylphosphonic acid, photosensitizer and acetone is 0.1 mol: 0.2 mol: 12 mg: 35 mL. After the reaction is completed, the acetone is removed by rotary evaporation to obtain the phosphating agent.

[0032] Step A2: Take the phosphating agent and add it to deionized water, stir and mix, control the mass fraction of the phosphating agent to be about 4%, heat it to 90°C as a load liquid, then take zirconium oxychloride octahydrate and fumaric acid, add dimethylacetamide and stir until completely dissolved, apply 33kHz ultrasonic vibration to the load liquid, slowly add the solution of zirconium oxychloride octahydrate and fumaric acid, control the addition rate to 2mL / min, pressurize the reaction system after complete addition, and heat the reaction system to 140°C to continue the reaction for 3h. In the reaction, the molar ratio of zirconium oxychloride octahydrate, fumaric acid and phosphating agent is 1:0.88:0.15. Centrifuge after the reaction is completed, take the bottom precipitate, wash and dry to obtain the phosphated MOF.

[0033] (2) Cast film

[0034] Step S1: Take isopropanol and dilute it to a volume fraction of 60%, add sodium hydroxide to alkalize to a pH value of 10, prepare an alkaline isopropanol aqueous solution, then add perfluorosulfonic acid resin and stir to dissolve, heat to 80°C and reflux for 2.5 hours, then add formic acid to neutralize, and then add 1.1wt% of perfluorosulfonic acid resin and phosphated MOF to mix, wherein the perfluorosulfonic acid resin adopts NR50 type raw material to obtain a casting solution.

[0035] Step S2: vacuum-dry the casting liquid, control the solid content of the drying to 17wt%, and transfer the discharged material to a steel belt casting machine for film casting. During the film casting process, the drying temperature zones are set to: 45°C in zone 1, 75°C in zone 2, 60°C in zone 3, and 50°C in zone 4. Remove the membrane material, immerse it in deionized water for cleaning, and dry it to obtain a high-temperature resistant hydrogen fuel cell ion exchange membrane.

[0036] Example 3, preparation of high temperature resistant hydrogen fuel cell ion exchange membrane, the specific implementation process is as follows:

[0037] (1) Preparation of phosphated MOF

[0038] Step A1: Mix vinylphosphonic acid, photosensitizer and acetone, add acetic acid to adjust the pH value of the reaction system to 4, control the temperature of the ice water bath to 10°C, apply mechanical stirring at 120 rpm, and apply 600 W / m 2 UV irradiation, take equal amounts of ethanedithiol and divide them into four parts, add them intermittently for 30 minutes, continue the constant temperature irradiation reaction after complete addition, and control the total reaction time of ethanedithiol addition to be 7.5 hours. In the above reaction, the photosensitizer uses high-efficiency photoinitiator 784, wherein the amount ratio of ethanedithiol, vinylphosphonic acid, photosensitizer and acetone is 0.1 mol: 0.2 mol: 10 mg: 30 mL. After the reaction is completed, the acetone is removed by rotary evaporation to obtain the phosphating agent.

[0039] Step A2: Take the phosphating agent and add it to deionized water, stir and mix, control the mass fraction of the phosphating agent to be about 5%, heat it to 90°C as a load liquid, then take zirconium oxychloride octahydrate and fumaric acid, add dimethylacetamide and stir until completely dissolved, apply 33kHz ultrasonic vibration to the load liquid, slowly add the dissolved solution of zirconium oxychloride octahydrate and fumaric acid, control the addition rate to 2mL / min, pressurize the reaction system after complete addition, and heat the reaction system to 130°C to continue the reaction for 3.5h. In the reaction, the molar ratio of zirconium oxychloride octahydrate, fumaric acid and phosphating agent is 1:0.92:0.11. Centrifuge after the reaction is completed, take the bottom precipitate, wash and dry to obtain the phosphated MOF.

[0040] (2) Cast film

[0041] Step S1: Take isopropanol and dilute it to a volume fraction of 60%, add sodium hydroxide to alkalize to a pH value of 10, prepare an alkaline isopropanol aqueous solution, then add perfluorosulfonic acid resin and stir to dissolve, heat to 80°C and reflux for 3h, then add formic acid to neutralize, and then add 1wt% of perfluorosulfonic acid resin and phosphated MOF to mix, wherein the perfluorosulfonic acid resin adopts NR50 type raw material to obtain a casting solution.

[0042] Step S2: vacuum-dry the casting liquid, control the solid content of the drying to 15wt%, and transfer the discharged material to a steel belt casting machine for film casting. During the film casting process, the drying temperature zones are set to: 50°C for zone 1, 80°C for zone 2, 70°C for zone 3, and 55°C for zone 4. Remove the membrane material, immerse it in deionized water for cleaning, and dry it to obtain a high-temperature resistant hydrogen fuel cell ion exchange membrane.

[0043] Example 4, preparation of high temperature resistant hydrogen fuel cell ion exchange membrane, the specific implementation process is as follows:

[0044] (1) Preparation of phosphated MOF

[0045] Step A1: Mix vinylphosphonic acid, photosensitizer and acetone, add acetic acid to adjust the pH value of the reaction system to 5, control the temperature of the reaction system to 10°C in an ice water bath, apply mechanical stirring at 120 rpm, and apply 680 W / m 2 Under ultraviolet irradiation, take equal amounts of ethanedithiol and divide them into four parts, add them intermittently for 30 minutes, continue the constant temperature irradiation reaction after complete addition, and control the total reaction time of ethanedithiol addition to be 6.5 hours. In the above reaction, the photosensitizer uses high-efficiency photoinitiator 784, wherein the amount ratio of ethanedithiol, vinylphosphonic acid, photosensitizer and acetone is 0.1 mol: 0.2 mol: 10 mg: 30 mL. After the reaction is completed, the acetone is removed by rotary evaporation to obtain the phosphating agent.

[0046] Step A2: Take the phosphating agent and add it to deionized water, stir and mix, control the mass fraction of the phosphating agent to be about 5%, heat it to 90°C as a load liquid, then take zirconium oxychloride octahydrate and fumaric acid, add dimethylacetamide and stir until completely dissolved, apply 33kHz ultrasonic vibration to the load liquid, slowly add the dissolved solution of zirconium oxychloride octahydrate and fumaric acid, control the addition rate to 1.5mL / min, pressurize the reaction system after complete addition, and heat the reaction system to 120°C to continue the reaction for 3.5h. In the reaction, the molar ratio of zirconium oxychloride octahydrate, fumaric acid and phosphating agent is 1:0.9:0.13. Centrifuge after the reaction is completed, take the bottom precipitate, wash and dry to obtain the phosphated MOF.

[0047] (2) Cast film

[0048] Step S1: Take isopropanol and dilute it to a volume fraction of 60%, add sodium hydroxide to alkalize it to a pH value of 9, prepare an alkaline isopropanol aqueous solution, then add perfluorosulfonic acid resin and stir to dissolve, heat to 80°C and reflux for 3h, then add formic acid to neutralize, and then add 1.1wt% of perfluorosulfonic acid resin and phosphated MOF to mix, wherein the perfluorosulfonic acid resin adopts NR50 type raw material to obtain a casting solution.

[0049] Step S2: vacuum-dry the casting liquid, control the solid content of the drying to 15wt%, and transfer the discharged material to a steel belt casting machine for film casting. During the film casting process, the drying temperature zones are set to: 50°C for zone 1, 80°C for zone 2, 70°C for zone 3, and 60°C for zone 4. Remove the membrane material, immerse it in deionized water for cleaning, and dry it to obtain a high-temperature resistant hydrogen fuel cell ion exchange membrane.

[0050] Comparative Example

[0051] This comparative example refers to Example 4, except that the phosphated MOF in the casting solution is replaced with MOF-801 powder of the same quality produced by Shanghai Kaishu Chemical Technology Co., Ltd. After the film is cast, it is immersed in phosphoric acid for 1 hour, washed with deionized water and dried to obtain an ion exchange membrane.

[0052] Take the above ion exchange membrane, and perform a tensile test according to GB 13022-1991 standard at a loading rate of 50 mm / min, and perform a tear test according to GB / T 11999-1989 standard at a loading rate of 20 mm / min;

[0053] The anhydrous proton conductivity of the above ion exchange membrane was measured at 80-160°C using a CHI-660e electrochemical workstation by four-electrode AC impedance method. 2The Pt / C gas diffusion electrode was assembled into a membrane electrode without hot pressing. The cathode and anode were respectively treated with 100 mL / min of O2 and 50 mL / min of H2. The single cell was tested at 160°C without back pressure and additional humidification to detect the peak power density.

[0054] The specific test data are shown in the following table:

[0055]

[0056] It can be seen from the test results in the above table that the ion exchange membrane prepared in the example has good mechanical properties and has a higher proton conductivity at high temperature.

[0057] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0058] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A high temperature resistant hydrogen fuel cell ion exchange membrane, characterized in that: Films are cast from phosphated MOF and perfluorosulfonic acid resin; The phosphated MOF is prepared by the following method: Step A1: vinylphosphonic acid, photosensitizer and acetone are mixed, the pH value of the reaction system is adjusted to 4-5 with acetic acid, the temperature is controlled to 5-15° C. in an ice-water bath, the mixture is stirred and irradiated with ultraviolet light, ethylenedithiol is added intermittently, and the total reaction time of ethylenedithiol addition is controlled to be 6-8 hours. After the reaction is completed, acetone is removed by rotary evaporation to obtain a phosphating agent; Step A2: The phosphating agent and deionized water are mixed and heated to 80-90°C as a loading liquid, and then zirconium oxychloride octahydrate and fumaric acid are dissolved in dimethylacetamide, and slowly added to the loading liquid under ultrasonic vibration. After complete addition, the pressure is increased and the temperature is increased to 120-140°C to continue the reaction for 3-4 hours. After the reaction is completed, centrifuge, take the bottom precipitate, wash and dry to obtain the phosphated MOF.

2. A high temperature resistant hydrogen fuel cell ion exchange membrane according to claim 1, characterized in that: The usage ratio of ethanedithiol, vinylphosphonic acid, photosensitizer and acetone is 0.1 mol: 0.2 mol: 8-12 mg: 25-35 mL.

3. A high temperature resistant hydrogen fuel cell ion exchange membrane according to claim 2, characterized in that: The photosensitizer is photoinitiator 784, and the UV irradiation intensity is 550-700W / m 2 .

4. A high temperature resistant hydrogen fuel cell ion exchange membrane according to claim 2, characterized in that: The molar ratio of zirconium oxychloride octahydrate, fumaric acid and phosphating agent is 1:0.88-0.95:0.1-0.15, and the mass fraction of the phosphating agent in the loading liquid is 4-6%.

5. The method for preparing a high temperature resistant hydrogen fuel cell ion exchange membrane according to claim 4, characterized in that: The steps include: Step S1: prepare an alkaline isopropanol aqueous solution with sodium hydroxide, add perfluorosulfonic acid resin to mix, heat and reflux for 2.5-3h, then neutralize with formic acid, add phosphated MOF and mix well to obtain a casting solution; Step S2: The casting liquid is vacuum-baked, and the material is transferred to a steel belt casting machine for casting into a film, and then immersed in deionized water for cleaning and drying to obtain a high-temperature resistant hydrogen fuel cell ion exchange membrane.

6. The method for preparing a high temperature resistant hydrogen fuel cell ion exchange membrane according to claim 5, characterized in that: The pH value of the alkaline isopropanol aqueous solution is 9-10, and the amount of phosphated MOF used is 0.9-1.1wt% of the perfluorosulfonic acid resin.

7. The method for preparing a high temperature resistant hydrogen fuel cell ion exchange membrane according to claim 5, characterized in that: The solid content of the casting solution after vacuum baking is 13-17wt%.

8. The method for preparing a high temperature resistant hydrogen fuel cell ion exchange membrane according to claim 7, characterized in that: During the tape casting process, the drying temperature zones are set as: zone one 45-55°C, zone two 75-90°C, zone three 60-70°C, zone four 50-60°C.

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