KR102483294B1 - Hollow fiber composite membrane for fuel cell electric vehicle and preparation method thereof - Google Patents

Abstract

The present invention is a hollow fiber support membrane of a polysulfone-based material; and a poly(ether-co-amide) block copolymer or polydimethylsiloxane resin mixture coating layer formed on the outer surface of the hollow fiber support membrane.
According to the present invention, a hollow fiber composite for a humidifier of a hydrogen fuel cell vehicle with significantly improved humidification performance of nitrogen permeability of 20 GPU or less and water permeability of 800 g/m ² ㅇhr due to reduced resistance to water vapor transmission and improved permeability membranes can be provided.

Description

Hollow fiber composite membrane for humidifier of hydrogen fuel cell vehicle and its manufacturing method {Hollow fiber composite membrane for fuel cell electric vehicle and preparation method thereof}

The present invention relates to a hollow fiber composite membrane for a humidifier of a hydrogen fuel cell vehicle and a method for manufacturing the same, and more particularly, coating the outer surface of a polysulfone hollow fiber support membrane with a hydrophilic poly(ether-co-amide) block copolymer By manufacturing a hollow fiber composite membrane, it relates to a technology of applying it to a membrane humidifier for a hydrogen fuel cell vehicle.

A polymer electrolyte membrane fuel cell (PEMFC) is a fuel cell that uses a polymer membrane with hydrogen ion exchange characteristics as an electrolyte. It has the characteristics of large, short start-up time and fast response to load change. In particular, since a polymer membrane is used as an electrolyte, corrosion and electrolyte control are not required, a methanol reformer, which is an existing technology, can be applied, and it is less sensitive to changes in reaction gas pressure. In addition, since it is simple in design, easy to manufacture, and can produce a wide range of output, it has the advantage of being able to be used as a power source for transportation institutions such as hydrogen fuel cell vehicles. As a result, many studies have been conducted and examples of successful commercialization have been announced.

In addition, a solid polymer membrane used in a polymer electrolyte fuel cell must have a certain amount of moisture present in the electrolyte for effective transfer of hydrogen ions. Therefore, during the operation of the fuel cell, the polymer membrane must always be hydrated, and when moisture is insufficient, the hydrogen ion conductivity decreases, and the contact resistance between the electrode and the membrane increases due to membrane shrinkage. Conversely, if there is a lot of moisture, it is difficult to diffuse the reaction gas on the surface of the catalyst and the performance of the fuel cell is reduced. Therefore, water management is very important in fuel cell operation.

Methods of humidifying the polymer membrane can be largely divided into external humidification and internal humidification. The method using an external humidifier, which is currently widely used, has problems in terms of energy efficiency because it needs to heat water to maintain appropriate humidity in the reaction gas. It also has its downsides. In order to compensate for these problems, recently, a method using membrane humidification, a method of supplying water using a porous cathode plate, and a method of supplying water to an electrolyte using a fiber wick have been attempted. Among them, the humidification method using a membrane is a method attempted by Ballard Power Systems, which can manufacture a humidifier integrally with a polymer electrolyte fuel cell stack, and can save separate energy for humidification by using the cooling system of the stack. There are advantages to being able to

In addition, as a prior art for application to a membrane humidifier of a fuel cell, a hollow fiber composite membrane in which a perfluorinated sulfonic acid copolymer is coated on the inner surface of a hollow fiber support membrane including polyetherimide is known. However, since the coating layer is formed on the inner surface of the hollow fiber support membrane, the hollow fiber composite membrane has a disadvantage in that the effective membrane area is reduced and the humidification performance is poor when applied to a membrane humidifier.

Therefore, as a result of repeated research to solve the above problems, the inventors of the present invention formed a hollow fiber support membrane with a polysulfone-based material, and formed a hydrophilic poly(ether-co-amide)-based block copolymer on the outer surface, not the inner surface thereof. Alternatively, by developing a hollow fiber composite membrane coated with a polydimethylsiloxane resin mixture, it is found that it can be applied as a membrane humidifier for a hydrogen fuel cell vehicle because the resistance to the transmission of water vapor is reduced and the humidification performance is greatly improved due to the improved permeability. has been completed.

Patent Document 1. Korean Patent Registration No. 10-1278398 Patent Document 2. Korean Patent Registration No. 10-1398779

The present invention has been made in view of the above problems, and an object of the present invention is to reduce the resistance to the transmission of water vapor and improve the permeability, resulting in nitrogen permeability of 20 GPU or less and moisture permeability of 800 g / m ² · hr Humidification It is intended to provide a hollow fiber composite membrane for a humidifier of a hydrogen fuel cell vehicle with greatly improved performance and a manufacturing method thereof.

The present invention for achieving the above object, a hollow fiber support membrane of a polysulfone-based material; and a poly(ether-co-amide)-based block copolymer or polydimethylsiloxane resin mixture coating layer formed on the outer surface of the hollow fiber support membrane.

The polysulfone-based material is characterized in that polysulfone, polyethersulfone or polyphenylenesulfone.

The poly(ether-co-amide)-based block copolymer is characterized in that it is represented by the following [Formula 1] or [Formula 2].

[Formula 1]

[Formula 2]

(In [Formula 1], PEO in the repeating unit of the block copolymer is polyethylene oxide, PA6 is polyamide 6, and its molar ratio is 6:4, and in [Formula 2], in the repeating unit of the block copolymer PTMO is polytetramethylene oxide, PA12 is polyamide 12, its molar ratio is 8:2)

The polydimethylsiloxane resin mixture is characterized in that graphene oxide, titanium dioxide or silica is blended with the polydimethylsiloxane resin.

The thickness of the coating layer is characterized in that 0.05 to 5 ㎛.

In addition, the present invention (I) mixing and stirring the polysulfone-based material, organic solvent and additives to obtain a uniform spinning solution; (II) forming a hollow fiber support film by spinning the spinning solution through a double spinneret; and (III) coating a poly(ether-co-amide)-based block copolymer or polydimethylsiloxane resin mixture solution on the outer surface of the hollow fiber support membrane. Preparation of a hollow fiber composite membrane for a humidifier of a hydrogen fuel cell vehicle including provides a way

The organic solvent in step (I) is any one selected from the group consisting of N-methylpyrrolidone (NMP), dimethylacetamide (DMAc), dimethylformamide (DMF) and dimethylsulfoxide (DMSO), do.

The spinning solution of step (I) is characterized in that the concentration is 20 to 40% by weight.

The additives in step (I) are tetrahydrofuran, methyl ethyl ketone, ethyl acetate, trichloroethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, dimethyl ether, diethyl ether, methanol, ethanol, 2-propanol , 1 selected from the group consisting of 2-pentanol, methoxyethanol, dioxane, butoxyethanol, perferyl alcohol, tersiamyl alcohol, acetic acid, citric acid, butyric acid, palmitic acid, oxalic acid, propionic acid, benzoic acid and tartaric acid Characterized by more than one species.

The solution of the poly(ether-co-amide)-based block copolymer or polydimethylsiloxane resin mixture in step (III) is characterized in that it has a concentration of 1 to 5% by weight.

According to the present invention, a hollow fiber composite for a humidifier of a hydrogen fuel cell vehicle with significantly improved humidification performance of nitrogen permeability of 20 GPU or less and water permeability of 800 g/m ² hr due to reduced resistance to water vapor transmission and improved permeability A membrane and a manufacturing method thereof can be provided.

1 is a schematic diagram and manufacturing process image of an apparatus for manufacturing a hollow fiber support membrane according to the present invention.
Figure 2 is a scanning electron microscope (SEM) image showing the structure of the hollow fiber composite membrane prepared from Example 1 of the present invention.
3 is a schematic diagram and a test sample image for measuring the nitrogen permeability of the hollow fiber composite membrane according to the present invention.

Hereinafter, a hollow fiber composite membrane for a humidifier of a hydrogen fuel cell vehicle and a manufacturing method thereof according to the present invention will be described in detail with accompanying drawings.

The present invention is a hollow fiber support membrane of a polysulfone-based material; and a poly(ether-co-amide)-based block copolymer or polydimethylsiloxane resin mixture coating layer formed on the outer surface of the hollow fiber support membrane.

An electrolyte that transfers hydrogen ions in a conventional PEMFC uses a polymeric ion exchange membrane and typically uses a sulfonated fluoropolymer. The polymer membrane serves not only as a carrier of hydrogen ions between the anode and cathode, but also as a barrier between oxygen and hydrogen, and must have high hydrogen ion conductivity and chemical stability. Companies that are developing polymer electrolyte membranes for PEMFC include Dupont, Asahi Chemical, and Asahi Glass. Among those developed by these companies, Nafion ^® (Dupont) shows the most reliable performance. is known as This polymer membrane contains sulfonic acid inside the hydrophobic material to create a hydrophilic region, and thus exhibits excellent ionic conductivity when the material absorbs moisture rather than when it is dry.

The reactive gas used in the PEMFC must be saturated with water to prevent dehydration of the membrane. In particular, excessive water generated at the cathode side must be removed, but since water evaporates at the anode side and the polymer membrane is dried, it is very important to effectively supply water to sufficiently maintain the moisture content of the polymer membrane. Methods for supplying moisture to the electrolyte membrane are largely divided into an external humidification method and an internal humidification method. In the external humidification method, a representative method is to pass the reactive gas through a bubble humidifier containing water and then introduce it into the battery. There are difficulties. In addition to this, there are a method using a porous membrane and a method of directly spraying fine water particles to the reaction gas. On the other hand, internal humidification methods include a method of using a porous separator by passing a reaction gas through a porous polymer membrane containing water, a method of supplying water, and a method of directly humidifying an electrolyte membrane.

The hollow fiber composite membrane for a humidifier of a hydrogen fuel cell vehicle, which is an object of the present invention, uses a polysulfone-based hollow fiber support membrane as a main substrate as one component thereof. That is, in order to apply the hollow fiber composite membrane to the humidifier system of a hydrogen fuel cell vehicle, one of the most important technical characteristics is the permeation characteristic of the hollow fiber support membrane.

Therefore, in the present invention, compared to conventional hydrophobic support membranes such as polyvinylidene fluoride (PVDF), by forming the support membrane with a glassy polymeric material having hydrophilicity, the resistance to the transmission of water vapor is reduced, resulting in improved permeability. A phonetic polymer is preferably used as a material for the hollow fiber support membrane.

As the polysulfone-based material, polysulfone (PS), polyethersulfone (PES), or polyphenylenesulfone (PPSU) may be used.

In addition, in the present invention, in order to construct a hollow fiber composite membrane for a humidifier of a hydrogen fuel cell vehicle, a poly(ether-co-amide) block copolymer or polydimethylsiloxane resin mixture coating layer is formed on the outer surface of the polysulfone-based hollow fiber support membrane. do.

The poly(ether-co-amide)-based block copolymer may be represented by the following [Formula 1] or [Formula 2].

[Formula 1]

[Formula 2]

(In [Formula 1], PEO in the repeating unit of the block copolymer is polyethylene oxide, PA6 is polyamide 6, and its molar ratio is 6:4, and in [Formula 2], in the repeating unit of the block copolymer PTMO is polytetramethylene oxide, PA12 is polyamide 12, its molar ratio is 8:2)

In particular, as the poly(ether-co-amide)-based block copolymer represented by [Formula 1], commercially available Pebax ^® 1657 is used as the poly(ether-co-amide)-based block copolymer represented by [Formula 2]. Commercially available Pebax ^® 2533 can be preferably used.

In addition, the polydimethylsiloxane resin mixture may be a mixture of graphene oxide, titanium dioxide, or silica in a polydimethylsiloxane resin.

At this time, the thickness of the coating layer may be 0.05 to 5 μm. If the thickness of the coating layer is less than 0.05 μm, it is difficult to form a coating layer without defects on the surface when manufacturing a large area hollow fiber module, and if it exceeds 5 μm, the coating layer It is preferable to adjust the thickness of the coating layer within the above range because the thickness may cause a disadvantage in that the water permeability is reduced due to the thick thickness.

In addition, the present invention (I) mixing and stirring the polysulfone-based material, organic solvent and additives to obtain a uniform spinning solution; (II) forming a hollow fiber support film by spinning the spinning solution through a double spinneret; and (III) coating a poly(ether-co-amide)-based block copolymer or polydimethylsiloxane resin mixture solution on the outer surface of the hollow fiber support membrane. Preparation of a hollow fiber composite membrane for a humidifier of a hydrogen fuel cell vehicle including provides a way

First, polysulfone (PS), polyethersulfone (PES), or polyphenylenesulfone (PPSU) may be used as the polysulfone-based material in the step (I).

As the organic solvent in the step (I), it is preferable to use a good solvent having a relatively high boiling point. If the boiling point is low, defects may occur in the hollow fiber support film due to rapid evaporation of the organic solvent during the high-temperature hollow fiber spinning process, and if the boiling point is too high, the organic solvent does not evaporate while the spinning solution passes through the air, resulting in a uniform morphology cannot be formed. Therefore, as the organic solvent, any one selected from the group consisting of N-methylpyrrolidone (NMP), dimethylacetamide (DMAc), dimethylformamide (DMF) and dimethylsulfoxide (DMSO) may be used, and N- Methylpyrrolidone (NMP) is more preferably used.

In addition, in order to obtain a uniform spinning solution, an additive is mixed with an organic solvent, and the additive is tetrahydrofuran, methylethyl, which serves to slightly reduce the viscosity of the polymer solution and maintain the state of the polymer spinning solution uniformly Ketone, ethyl acetate, trichloroethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, dimethyl ether, diethyl ether, methanol, ethanol, 2-propanol, 2-pentanol, methoxyethanol, dioxane, butoxy It may be at least one selected from the group consisting of ethanol, perferyl alcohol, tertiary acid, acetic acid, citric acid, butyric acid, palmitic acid, oxalic acid, propionic acid, benzoic acid, and tartaric acid, and propionic acid is more preferably used.

In addition, the additive is added in an amount of 10 to 30 parts by weight based on 100 parts by weight of the spinning solution. If the content of the additive is less than 10 parts by weight, it is difficult to obtain a uniform spinning solution while reducing the viscosity of the polymer solution, and it is more than 30 parts by weight. If the ratio of the highly volatile solvent is high, the uniformity of the spinning solution is not secured and the physical properties of the hollow fiber are easily changed over time, so it is preferable to maintain the content of the additive within the above range.

In addition, the spinning solution in step (I) is adjusted to a concentration of 20 to 40% by weight. If the concentration is less than 20% by weight, the mechanical strength of the hollow fiber is weak, making it difficult to serve as a support, and the concentration exceeds 40% by weight. Since the permeability of water vapor may be very low, it is preferable to maintain the concentration within the above range.

A hollow fiber support membrane is obtained by spinning the spinning solution through a double spinneret using the apparatus for manufacturing a hollow fiber support membrane shown in FIG. 1 . First, the spinning solution is sent to the double spinneret while maintaining 60 to 80 ° C. and an air gap of 1 to 30 cm through a gear pump after removing air bubbles and foreign substances using a filter. Subsequently, the spinning solution comes out through the outer nozzle of the double spinneret, and the inner coagulating solution is discharged to the inside of the double spinneret to spin the hollow fiber. At this time, the internal coagulating solution is selected from the group consisting of water, isopropanol, butanol, ethylene glycol, polyethylene glycol, glycerol, dimethoxyethanol, diethoxyethanol, butoxymethanol, dimethoxybutylene oxide or diglycidyldimethyl ether Any one may be used, but it is more preferable to use water. In addition, the external coagulation bath containing water, which is an external coagulation solution, is maintained at 20 to 30 ° C, and the hollow fiber is wound through a phase transition process, washed in running water for 2 to 3 days to remove residual solvents and additives, and then washed in methanol for 3 to 3 days. It is immersed for 5 hours, dipped again in n-hexane for 3 to 5 hours to replace methanol with n-hexane, and then dried in an oven at 70 to 80 ° C. for 3 hours or more to obtain a hollow fiber support membrane.

In addition, in the present invention, a hollow fiber composite membrane for a humidifier of a hydrogen fuel cell vehicle, which is a target object, is prepared by coating a poly(ether-co-amide)-based block copolymer solution on the outer surface of the hollow fiber support membrane, the poly(ether-co-amide) As the co-amide)-based block copolymer, those represented by [Formula 1] or [Formula 2] described above are preferably used.

The poly(ether-co-amide)-based block copolymer solution is obtained by using a 60% aqueous ethanol solution or a mixture of n-butanol/isopropanol (4:6 weight ratio) as a solvent. At this time, the poly(ether-co-amide)-based block copolymer solution for the coating is adjusted to a concentration of 1 to 5% by weight. If the concentration of the coating solution is less than 1% by weight, it is difficult to coat defects on the outer surface of the hollow fiber. Since the concentration is too low, the coating does not work properly, which reduces the water permeability of the hollow fiber composite membrane, and when the concentration exceeds 5% by weight, it is difficult to form a uniform coating layer. It is desirable to regulate

[Example 1]

500 g of N-methylpyrrolidone was added to a 2L reactor equipped with a stirrer, 250 g of propionic acid was mixed as an additive, and then 250 g of polysulfone was slowly added and stirred to obtain a uniform spinning solution. Air bubbles were removed from the spinning solution, and foreign substances were removed using a 60 μm filter. Subsequently, it was sent to a double spinneret while maintaining a spinning temperature of 60 ° C and an air gap of 10 cm through a gear pump. At this time, water at room temperature was used as the internal coagulating solution of the double spinneret. The temperature of the external coagulation bath containing water was set to 20 ° C., and after the phase transition process, the hollow fiber was wound up and washed in running water for 2 days to remove the remaining solvent and additives. Then, it was immersed in methanol for 3 hours, dipped in n-hexane again for 3 hours to replace methanol with hexane, and then dried in a vacuum oven at 70° C. for 4 hours to obtain a hollow fiber support membrane. The outer surface of the obtained hollow fiber support membrane was dip-coated with a coating solution in which Pebax ^® 1657 was dissolved in a 60% aqueous ethanol solution at a concentration of 2% by weight, and then dried at 80 ° C. for 12 hours to prepare a hollow fiber composite membrane (thickness of the coating layer 0.9 μm).

[Example 2]

The same method as in Example 1 except for the process of dip coating the outer surface of the hollow fiber support membrane with a coating solution in which Pebax ^® 2533 was dissolved in a mixed solvent of n-butanol/isopropanol (4:6 weight ratio) at a concentration of 2% by weight. A hollow fiber composite membrane was prepared.

[Example 3]

The outer surface of the hollow fiber support membrane is coated with a mixture of polydimethylsiloxane resin and graphene oxide (graphene oxide is mixed at 3% by weight of polydimethylsiloxane resin, and polydimethylsiloxane resin is mixed at 1% by weight of n-hexane). A hollow fiber composite membrane was prepared in the same manner as in Example 1, except for the dip coating process.

[Comparative Example 1]

A hollow fiber composite membrane was prepared in the same manner as in Example 1, except that the thickness of the coating layer formed on the outer surface of the hollow fiber support membrane was 0.04 μm.

[Comparative Example 2]

A hollow fiber composite membrane was prepared in the same manner as in Example 1, except that the thickness of the coating layer formed on the outer surface of the hollow fiber support membrane was 6 μm.

Figure 2 shows a scanning electron microscope (SEM) image showing the structure of the hollow fiber composite membrane prepared from Example 1 of the present invention, Pebax ^?? on the outer surface of the polysulfone hollow fiber support membrane. It can be confirmed that a uniform coating layer of 1657 is formed.

In addition, as shown in the schematic diagram and test sample image for measuring the nitrogen permeability of the hollow fiber composite membrane shown in FIG. 3, a test sample was prepared and nitrogen permeability was evaluated using a nitrogen cylinder. The hollow fiber test module was measured using a bubble flow meter at 25°C and 2-5 barg. In addition, the water permeability of the hollow fiber composite membrane was evaluated according to the ASTM F 1249 method.

Table 1 below shows the nitrogen permeability of the hollow fiber support membranes and the hollow fiber composite membranes prepared from Examples 1 to 3 and Comparative Examples 1 and 2 of the present invention, and water permeability of the hollow fiber composite membranes.

Sample Nitrogen permeability of the hollow fiber support membrane
(GPUs) Composite Membrane Nitrogen Permeability
(GPUs) Composite membrane water permeability
(g/m ² ·hr) Example 1 18,000 3.4 830 Example 2 18,000 2.5 801 Example 3 18,000 4.4 809 Comparative Example 1 18,000 134 1,227 Comparative Example 2 18,000 0.9 699

*(GPU=cm ³ /cm ² ·sec·cmHg)

As shown in Table 1, the hollow fiber composite membranes prepared from Examples 1 to 3 of the present invention have a nitrogen permeability of 20 GPU or less and a water permeability of 800 g / m ² ㅇhr, significantly improving humidification performance compared to conventional membrane humidifiers As a result, it can be confirmed that it can be sufficiently applied as a hollow fiber composite membrane for a humidifier of a hydrogen fuel cell vehicle.

On the other hand, the hollow fiber composite membrane prepared from Comparative Example 1 had a very thin coating layer, so the water permeability was greatly improved, but the nitrogen permeability was extremely high. Since the water permeability is also very low, the hollow fiber composite membranes prepared in Comparative Examples 1 and 2 are difficult to apply as hollow fiber composite membranes for humidifiers of hydrogen fuel cell vehicles, unlike the hollow fiber composite membranes prepared in Examples 1 to 3. .

Claims (10)

a hollow fiber support membrane made of a polysulfone-based material; and
A hollow fiber composite film for a humidifier of a hydrogen fuel cell vehicle comprising a polydimethylsiloxane resin mixture coating layer in which graphene oxide, titanium dioxide, or silica is blended with a polydimethylsiloxane resin formed on an outer surface of the hollow fiber support film. The hollow fiber composite membrane for a humidifier of a hydrogen fuel cell vehicle according to claim 1, wherein the polysulfone-based material is polysulfone, polyethersulfone, or polyphenylenesulfone. delete delete The hollow fiber composite membrane for a humidifier of a hydrogen fuel cell vehicle according to claim 1, wherein the coating layer has a thickness of 0.05 to 5 μm. (I) obtaining a uniform spinning solution by mixing and stirring the polysulfone-based material, organic solvent and additives;
(II) forming a hollow fiber support film by spinning the spinning solution through a double spinneret; and
(III) coating a solution of a polydimethylsiloxane resin mixture in which graphene oxide, titanium dioxide, or silica is mixed with a polydimethylsiloxane resin on the outer surface of the hollow fiber support film; a hollow fiber composite for a humidifier of a hydrogen fuel cell vehicle including A method for producing membranes. The method of claim 6, wherein the organic solvent in step (I) is selected from the group consisting of N-methylpyrrolidone (NMP), dimethylacetamide (DMAc), dimethylformamide (DMF) and dimethylsulfoxide (DMSO) A method for manufacturing a hollow fiber composite membrane for a humidifier of a hydrogen fuel cell vehicle, characterized in that any one of them. The method of claim 6, wherein the spinning solution in step (I) has a concentration of 20 to 40% by weight. The method of claim 6, wherein the additive in step (I) is tetrahydrofuran, methyl ethyl ketone, ethyl acetate, trichloroethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, dimethyl ether, diethyl ether, methanol , ethanol, 2-propanol, 2-pentanol, methoxyethanol, dioxane, butoxyethanol, perferyl alcohol, tertiary alcohol, acetic acid, citric acid, butyric acid, palmitic acid, oxalic acid, propionic acid, benzoic acid and tartaric acid Method for manufacturing a hollow fiber composite membrane for a humidifier of a hydrogen fuel cell vehicle, characterized in that at least one selected from the group consisting of. The method of claim 6, wherein the polydimethylsiloxane resin mixture solution in step (III) has a concentration of 1 to 5% by weight.

Images