阅读说明：本技术 离子交换膜、其制造方法及包括其的能量存储装置 (Ion exchange membrane, method of manufacturing the same, and energy storage device including the same ) 是由 李殷受 李瞳熏 金娜玲 廉承辑 于 2018-02-28 设计创作，主要内容包括：本发明涉及一种离子交换膜、该离子交换膜的制造方法以及包括该离子交换膜的能量存储系统。离子交换膜包括：包括多个孔的多孔支撑体；位于多孔支撑体的一个表面上的第一离子导电材料；以及位于多孔支撑体的另一个表面上的第二离子导电材料,其中,第一离子导电材料和第二离子导电材料是包括亲水性重复单元和疏水性重复单元的聚合物,并且第一离子导电材料和第二离子导电材料具有不同的、亲水性重复单元与疏水性重复单元的摩尔比。根据该离子交换膜,由于优异的离子导电性能以及降低的膜电阻而提高能量存储系统的性能效率和电压效率这两者,从而能够提高能量存储系统的总效率,并且通过具有优异的形态稳定性并降低钒离子的交叉,能够确保能量存储系统的耐久性。(The present invention relates to an ion exchange membrane, a method of manufacturing the ion exchange membrane, and an energy storage system including the ion exchange membrane. The ion exchange membrane comprises: a porous support comprising a plurality of pores; a first ion-conducting material on one surface of the porous support; and a second ion conducting material on the other surface of the porous support, wherein the first and second ion conducting materials are polymers comprising hydrophilic and hydrophobic repeat units, and the first and second ion conducting materials have different molar ratios of hydrophilic to hydrophobic repeat units. According to the ion exchange membrane, both performance efficiency and voltage efficiency of the energy storage system are improved due to excellent ion conductivity properties and reduced membrane resistance, so that the overall efficiency of the energy storage system can be improved, and durability of the energy storage system can be ensured by having excellent morphological stability and reducing crossover of vanadium ions.)

1. An ion exchange membrane comprising:

A porous support comprising a plurality of pores;

A first ion conducting material on one surface of the porous support; and

A second ion-conducting material on the other surface of the porous support,

Wherein the first ion-conducting material and the second ion-conducting material are polymers comprising hydrophilic repeating units and hydrophobic repeating units, and

The first and second ion-conducting materials have different molar ratios of the hydrophilic repeat units to the hydrophobic repeat units.

2. The ion exchange membrane of claim 1, wherein the first and second ion conducting materials each independently have a molar ratio of the hydrophilic repeat units to the hydrophobic repeat units of 1:0.5 to 1: 10.

3. The ion exchange membrane of claim 1, wherein the molar ratio of the hydrophilic repeat units to the hydrophobic repeat units of the first ion-conducting material is higher than the molar ratio of the hydrophilic repeat units to the hydrophobic repeat units of the second ion-conducting material.

4. The ion exchange membrane according to claim 1, wherein a molar ratio of the hydrophilic repeating units to the hydrophobic repeating units in the first ion-conducting material is 1:2 to 1:5, and a molar ratio of the hydrophilic repeating units to the hydrophobic repeating units in the second ion-conducting material is 1:3 to 1: 6.

5. The ion exchange membrane of claim 1, wherein the thickness ratio of the first ion conducting material to the second ion conducting material is from 9:1 to 1: 9.

6. the ion exchange membrane of claim 1, wherein the first and second ion conducting materials are each independently a hydrocarbon-based ion conducting material and the porous support is a hydrocarbon-based porous support.

7. The ion exchange membrane according to claim 1, wherein the first ion conductive material and the second ion conductive material are each independently filled in the pores of the porous support.

8. The ion exchange membrane of claim 1, further comprising a first ionically conductive layer on one surface of the porous support and a second ionically conductive layer on the other surface of the porous support,

Wherein the first ion-conducting layer comprises the first ion-conducting material, and

The second ionically conductive layer comprises the second ionically conductive material.

9. The ion exchange membrane of claim 8, wherein the thickness of the first and second ionically conductive layers is each independently 10 to 200 percent length, relative to the total thickness of the porous support.

10. The ion exchange membrane of claim 8, wherein the ion exchange membrane comprises: a first ion-conductive material filled in pores of the porous support; a first ionically conductive layer located on one surface of the porous support; and a second ion-conducting layer on the other surface of the porous support.

11. The ion exchange membrane according to claim 1, wherein a plurality of porous support bodies including the first ion conductive material and the second ion conductive material are laminated.

12. The ion exchange membrane of claim 11, wherein the first or second ion conducting material of the first porous support is laminated to face the first or second ion conducting material of the second porous support.

13. a method of manufacturing an ion exchange membrane, comprising:

Preparing a porous support comprising a plurality of pores;

Forming a first ion-conducting material on one surface of the porous support; and

Forming a second ion-conducting material on the other surface of the porous support,

Wherein the first ion-conducting material and the second ion-conducting material are polymers comprising hydrophilic repeating units and hydrophobic repeating units, and

The first and second ion-conducting materials have different molar ratios of the hydrophilic repeat units to the hydrophobic repeat units.

14. The method for producing an ion exchange membrane according to claim 13, further comprising:

Preparing a plurality of porous supports comprising the first ion-conducting material and the second ion-conducting material; and

Stacking the plurality of porous supports.

15. An energy storage system comprising the ion exchange membrane of claim 1.

16. The energy storage system of claim 15, wherein the energy storage system is a fuel cell.

17. The energy storage system of claim 15, wherein the energy storage system is a redox flow battery.

Technical Field

The present invention relates to an ion exchange membrane, a method of manufacturing the same, and an energy storage system including the same, and more particularly, to an ion exchange membrane capable of improving the overall efficiency of an energy storage system by improving both the performance efficiency and the voltage efficiency of the energy storage system due to excellent ion conductivity properties and reduced membrane resistance, and ensuring the durability of the energy storage system by having excellent morphological stability and reducing the crossover (crossover) of vanadium ions, a method of manufacturing the same, and an energy storage device including the same.

Background

Efforts are being made to save fossil fuels or to apply renewable energy to more fields by improving use efficiency, thereby solving the problems of fossil fuel depletion and environmental pollution.

Renewable energy sources such as solar heat and wind power have been used more efficiently than before, but these energy sources are intermittent and unpredictable. Because of these characteristics, the dependence on these energy sources is limited and the proportion of renewable energy sources relative to the current main power source is very low.

Rechargeable batteries have been miniaturized to improve their portability since they provide a simple and efficient power storage method, and there is a constant effort to use rechargeable batteries as power sources for small household appliances such as intermittent auxiliary power sources, notebook computers, tablet computers, and mobile phones.

Among them, a Redox Flow Battery (RFB) is a secondary battery capable of storing energy for a long time by repeating charge and discharge through an electrochemical reversible reaction of an electrolyte. The cell stack and the electrolyte tank, which depend on the capacity and output characteristics of the cell, are independent of each other, so that the cell design is free and the restriction of the installation space is small.

In addition, the redox flow battery has: a load balancing function installed in power plants, power systems, and buildings to cope with sudden increases in power demand; a function of compensating or suppressing a power failure or instantaneous undervoltage, and the like. Redox flow batteries are very powerful storage technologies that can be freely combined as needed and are systems suitable for large-scale energy storage.

Redox flow batteries typically consist of two separate electrolytes. One electrolyte stores the electroactive species in the anodic reaction and the other electrolyte is used for the cathodic reaction. In an actual redox flow battery, the electrolyte reaction is different between the cathode and the anode, and there is a flow phenomenon of the electrolyte solution, thereby generating a pressure difference between the cathode side and the anode side. In all vanadium-based redox flow batteries as representative redox flow batteries, reactions of a catholyte and an anolyte are shown in the following reaction formulas 1 and 2, respectively.

[ reaction formula 1]

[ reaction formula 2]

Therefore, in order to overcome the pressure difference between the two electrodes and exhibit excellent battery performance even though charge and discharge are repeated, an ion exchange membrane having improved physical and chemical durability is required. In redox flow batteries, the ion exchange membrane is the core material that makes up about 10% of the system.

Therefore, in a redox flow battery, an ion exchange membrane is a main component for determining the life and price of the battery. In order to commercialize a redox flow battery, low crossover (cross) between vanadium ions is required due to high ion selective permeability of an ion exchange membrane, high ionic conductivity is required due to low electrical resistance, and low price is required in addition to mechanical and chemical stability and high durability.

Meanwhile, currently, polymer electrolyte membranes commercialized as ion exchange membranes have been used for decades and have been continuously studied. Recently, many studies on ion exchange membranes have been actively conducted as a medium for transporting ions used in Direct Methanol Fuel Cells (DMFC), polymer electrolyte membrane fuel cells (proton exchange membrane fuel cells, PEMFC), redox flow batteries, water purification, and the like.

Currently, a widely used material for ion exchange membranes is a perfluorosulfonic acid (TM) -based membrane, which is a perfluorosulfonic acid group-containing polymer manufactured by DuPont, u.s.a. The membrane has an ionic conductivity of 0.08S/cm and excellent mechanical strength and chemical resistance at room temperature at a saturated moisture content, and has stable performance as an electrolyte membrane used in an automotive fuel cell. Further, as the commercialized membranes of similar types, there are Aciplex-S membrane from Asahi Chemicals, Dow membrane from Dow Chemicals, Flemion membrane from Asahi Glass, GoreSelcet membrane from Gore & Association, and the like. In the barard Power System (Ballard Power System) in canada, alpha-type or beta-type perfluoropolymers have been developed and studied.

however, these membranes have disadvantages in that not only are mass production difficult due to high price and complicated synthesis method, but also in an electric energy system such as a redox flow battery, efficiency is greatly reduced as an ion exchange membrane due to such as crossover phenomenon and low ionic conductivity at high or low temperature.

Disclosure of Invention

Technical problem

An object of the present invention is to provide an ion exchange membrane capable of improving the overall efficiency of an energy storage system by improving both performance efficiency and voltage efficiency of the energy storage system due to excellent ion conductivity properties and reduced membrane resistance, and ensuring durability of the energy storage system by having excellent morphological stability and reducing crossover of vanadium ions.

Another object of the present invention is to provide a method for manufacturing an ion exchange membrane, which is capable of manufacturing an ion exchange membrane having the above-described properties through an existing process, and capable of manufacturing an ion exchange membrane having high efficiency while easily adjusting a thickness ratio required in an energy storage system.

It is a further object of the present invention to provide an energy storage system comprising the ion exchange membrane.

Technical scheme

According to an embodiment of the present invention, there is provided an ion exchange membrane including: a porous support comprising a plurality of pores; a first ion conducting material on one surface of a porous support; and a second ion-conducting material on the other surface of the porous support.

The first and second ion-conducting materials may be polymers comprising hydrophilic and hydrophobic repeat units, and the first and second ion-conducting materials may have different molar ratios of hydrophilic to hydrophobic repeat units.

The first ion-conducting material and the second ion-conducting material may each independently have a molar ratio of hydrophilic repeat units to hydrophobic repeat units of 1:0.5 to 1: 10.

The molar ratio of hydrophilic repeat units to hydrophobic repeat units of the first ion-conducting material may be higher than the molar ratio of hydrophilic repeat units to hydrophobic repeat units of the second ion-conducting material.

The molar ratio of the hydrophilic repeating units to the hydrophobic repeating units in the first ion-conductive material may be 1:2 to 1:5, and the molar ratio of the hydrophilic repeating units to the hydrophobic repeating units in the second ion-conductive material may be 1:3 to 1: 6.

The thickness ratio of the first ion conductive material to the second ion conductive material may be 9:1 to 1: 9.

The first ion conducting material and the second ion conducting material may each independently be a hydrocarbon-based ion conducting material, and the porous support may be a hydrocarbon-based porous support.

The first ion conductive material and the second ion conductive material may be each independently filled in the pores of the porous support.

The ion exchange membrane may further comprise a first ion-conducting layer on one surface of the porous support and a second ion-conducting layer on the other surface of the porous support, wherein the first ion-conducting layer may comprise a first ion-conducting material and the second ion-conducting layer may comprise a second ion-conducting material.

The thickness of the first and second ionically conductive layers may each independently be from 10 to 200 length% relative to the total thickness of the porous support.

The ion exchange membrane may include: a first ion-conductive material filled in the pores of the porous support; a first ionically conductive layer located on one surface of the porous support; and a second ion-conducting layer on the other surface of the porous support.

A plurality of porous supports including a first ion conductive material and a second ion conductive material may be stacked.

The first ion conducting material or the second ion conducting material of the first porous support may be laminated to face the first ion conducting material or the second ion conducting material of the second porous support.

According to another embodiment of the present invention, there is provided a method of manufacturing an ion exchange membrane, the method including: preparing a porous support comprising a plurality of pores; forming a first ion-conducting material on one surface of a porous support; and forming a second ion-conducting material on the other surface of the porous support.

The first and second ion-conducting materials may be polymers including hydrophilic and hydrophobic repeat units, and the first and second ion-conducting materials may have different molar ratios of hydrophilic to hydrophobic repeat units.

The method for producing an ion exchange membrane may further comprise: preparing a plurality of porous supports comprising a first ionically conductive material and a second ionically conductive material; and laminating a plurality of porous supports.

According to yet another embodiment of the present invention, an energy storage system is provided that includes an ion exchange membrane.

The energy storage system may be a fuel cell.

The energy storage system may be a redox flow battery.

Advantageous effects

According to the ion exchange membrane of the present invention, the overall efficiency of the energy storage system can be improved by improving both the performance efficiency and the voltage efficiency of the energy storage system due to the excellent ion conductivity properties and the reduced membrane resistance, and the durability of the energy storage system can be ensured by having excellent morphological stability and reducing the crossover of vanadium ions.

According to the method for manufacturing an ion exchange membrane of the present invention, an ion exchange membrane having the above-described properties can be manufactured by an existing process, and an ion exchange membrane having high efficiency can be manufactured while easily adjusting a thickness ratio required in an energy storage system.

Drawings

Fig. 1 is a sectional view schematically showing an ion exchange membrane according to an embodiment of the present invention.

Fig. 2 and 3 are sectional views schematically showing an ion exchange membrane in which a plurality of ion exchange membranes shown in fig. 1 are laminated.

Fig. 4 is a schematic view schematically showing all vanadium-based redox batteries according to another embodiment of the present invention.

Fig. 5 is a schematic view showing an apparatus for measuring the resistance of a film in experimental example 1 of the present invention.

Fig. 6 and 7 are AFM images of one surface and the other surface of the ion exchange membrane manufactured in example 1-1 of the present invention.

Detailed Description

Hereinafter, examples of the present invention will be described in detail so as to be easily implemented by those skilled in the art. The invention may, however, be embodied in many different forms and is not limited to the examples described herein.

Unless otherwise stated in the specification, the alkyl group includes a primary alkyl group, a secondary alkyl group and a tertiary alkyl group, and means a linear or branched alkyl group having 1 to 10 carbon atoms, the haloalkyl group means a linear or branched haloalkyl group having 1 to 10 carbon atoms, the allyl group means an allyl group having 2 to 10 carbon atoms, the aryl group means an aryl group having 6 to 30 carbon atoms, the alkoxy group means an alkoxy group having 1 to 10 carbon atoms, the alkylsulfonyl group means an alkylsulfonyl group having 1 to 10 carbon atoms, the acyl group means an acyl group having 1 to 10 carbon atoms, and the aldehyde group means an aldehyde group having 1 to 10 carbon atoms.

Unless otherwise stated in the specification, the amino group includes a primary amino group, a secondary amino group, and a tertiary amino group, and the secondary amino group or the tertiary amino group is an amino group having 1 to 10 carbon atoms.

In this specification, unless otherwise specified, all compounds or substituents may be substituted or unsubstituted. Here, the term "substituted" means that hydrogen is substituted with any one selected from the group consisting of a halogen atom, a hydroxyl group, a carboxyl group, a cyano group, a nitro group, an amino group, a thio group, a methylthio group, an alkoxy group, a nitroxyl group, an aldehyde group, an epoxy group, an ether group, an ester group, a carbonyl group, an acetal group, a ketone group, an alkyl group, a perfluoroalkyl group, a cycloalkyl group, a heterocycloalkyl group, an allyl group, a benzyl group, an aryl group, a heteroaryl group, a derivative thereof, and a combination thereof.

In the present specification, a symbol represented at both ends of a chemical formula indicates that the chemical formula is connected to another adjacent chemical formula.

In the present specification, the ion-conductive material including the repeating unit represented by one general formula may refer not only to an ion-conductive material including only the repeating unit represented by one chemical formula included in the general formula but also to an ion-conductive material including the repeating unit represented by various chemical formulas included in the general formula.

an ion exchange membrane according to an embodiment of the present invention includes: a porous support having a plurality of pores; and an ion conductive material filled in the pores of the porous support.

As an example, the porous support may include a perfluorinated polymer having excellent resistance to thermal and chemical degradation. For example, the porous support may be Polytetrafluoroethylene (PTFE) or tetrafluoroethylene and CF₂＝CFC_nF_2n+1(n is an integer of 1 to 5) or CF₂＝CFO-(CF₂CF(CF₃)O)_mC_nF_2n+1(m is an integer of 0 to 15, and n is an integer of 1 to 15).

PTFE is commercially available and can be suitably used as the porous support. Furthermore, a foamed polytetrafluoroethylene polymer (e-PTFE) having a microstructure of polymer fibrils or a microstructure in which nodes are connected to each other by fibrils can be suitably used as the porous support, and a membrane having a microstructure of polymer fibrils without nodes (nodes) can also be suitably used as the porous support.

The porous support comprising the perfluorinated polymer may be prepared as a more porous and stronger porous support by extrusion molding dispersion polymerized PTFE onto a belt in the presence of a lubricant and then stretching the material thus obtained. In addition, the amorphous content of PTFE can be increased by heat treating e-PTFE at a temperature above the melting point of PTFE (about 342 ℃). The e-PTFE membranes prepared by the above methods may have micropores including various diameters and porosities. The e-PTFE membrane prepared by the above method may have at least 35% of pores, and the diameter of the micropores may be about 0.01 μm to 1 μm. In addition, the thickness of the porous support including the perfluorinated polymer may be changed in various ways, but may be, for example, 2 μm to 40 μm, preferably 5 μm to 20 μm. If the thickness of the porous support is less than 2 μm, the mechanical strength is significantly reduced, and if the thickness of the porous support is greater than 40 μm, the resistance loss (resistance loss) may increase, and the weight reduction and the degree of integration may decrease.

As another example of a porous support, the porous support may be a nonwoven web formed from a plurality of randomly oriented fibers.

Nonwoven webs are interwoven, but refer to sheets having a structure of individual fibers or filaments rather than in the same manner as woven fabrics. The nonwoven web may be prepared by any one method selected from the group consisting of carding, garnetting, air-laying, wet-laying, melt-blowing, spunbonding, and stitch-bonding.

The fibers may comprise more than one polymeric material, and any material used as a fiber-forming polymeric material may generally be used, in particular hydrocarbon-based fibers may be used to form the polymeric material. For example, the fiber-forming polymer material may include any one selected from the group consisting of polyolefins such as polybutylene, polypropylene and polyethylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyamides (nylon-6 and nylon-6, 6), polyurethanes, polybutylene, polylactic acid, polyvinyl alcohol, polyphenylene sulfide, polysulfone, fluid crystalline polymers, polyethylene-co-vinyl acetate (polyethylene-co-vinyl acetate), polyacrylonitrile, cyclic polyolefins, polyoxymethylene, polyolefin thermoplastic elastomers, and combinations thereof, but the present invention is not limited thereto.

As yet another example of a porous support in the form of a nonwoven web, the porous support may comprise a nanoweb in which nanofibers are integrated in the form of a nonwoven fabric comprising a plurality of pores.

The nanofibers may preferably use a hydrocarbon-based polymer that exhibits excellent chemical resistance and has no fear of morphological changes due to moisture in a high humidity environment due to hydrophobicity. Specifically, as the hydrocarbon-based polymer, any one selected from the group consisting of nylon, polyimide, polyaramide, polyetherimide, polyacrylonitrile, polyaniline, polyethylene oxide, polyethylene naphthalate, polybutylene terephthalate, styrene-butadiene rubber, polystyrene, polyvinyl chloride, polyvinyl alcohol, polyvinylidene fluoride, polyethylene butylene, polyurethane, polybenzoxazole, polybenzimidazole, polyamideimide, polyethylene terephthalate, polyphenylene sulfide, polyethylene, polypropylene, copolymers thereof, and mixtures thereof may be used, and among these, polyimide having excellent heat resistance, chemical resistance, and morphological stability may be preferably used.

The nanofiber web is an aggregate of nanofibers in which the nanofibers prepared by electrospinning are randomly arranged. At this time, when the diameters of 50 fibers are measured using a scanning electron microscope (JSM6700F, JEOL) and calculated from the average thereof, it is preferable that the nanofibers have an average diameter of 40nm to 5000nm in consideration of the porosity and thickness of the nanoweb. If the average diameter of the nanofibers is less than 40nm, the mechanical strength of the porous support may be reduced, and if the average diameter of the nanofibers is greater than 5000nm, the porosity may be significantly reduced and the thickness may be increased.

The nonwoven web may have a thickness of 10 μm to 50 μm, specifically 15 μm to 43 μm. If the thickness of the nonwoven web is less than 10 μm, the mechanical strength may be reduced, and if the thickness of the nonwoven web is greater than 50 μm, the resistance loss may be increased, and the weight reduction and the degree of integration may be reduced.

The basis weight of the nonwoven web may be 5g/m²To 30g/m². If the basis weight of the nonwoven web is less than 5g/m²It may be difficult to use as a porous support due to the formation of visible pores if the basis weight is greater than 30g/m²The porous support may be manufactured in the form of paper or fabric with few pores formed.

The porosity of the porous support may be 45% or more, specifically 60% or more. Meanwhile, the porous support preferably has a porosity of 90% or less. If the porosity of the porous support is more than 90%, morphological stability may be reduced, so that post-treatment may not be smoothly performed. The porosity can be calculated by the ratio of the volume of air to the total volume of the porous support according to the following formula 1. At this time, the total volume is calculated by manufacturing a rectangular sample and measuring the width, length and thickness of the rectangular sample, and the volume of the polymer inversely calculated from the density after measuring the mass of the sample is subtracted from the total volume to obtain the volume of the air.

[ formula 1]

Porosity (%) × (volume of air in porous support/total volume of porous support) × 100

The ion exchange membrane is an ion exchange membrane in the form of a reinforced composite membrane, and in the reinforced composite membrane, the pores of a porous support body are filled with ion conductive materials.

The ion conductive material may be a cation conductive material having a cation exchange group such as a proton, or an anion conductive material having an anion exchange group such as a hydroxyl ion, carbonate, or bicarbonate.

The cation exchange group may be any one selected from the group consisting of a sulfonic acid group, a carboxyl group, a boric acid group, a phosphoric acid group, an imide group, a sulfonylimide group, a sulfonamide group, and a combination thereof, and may be generally a sulfonic acid group or a carboxyl group.

The cation conductive material includes cation exchange groups, and may include: a fluorine-based polymer including fluorine in a main chain; hydrocarbon-based polymers, for example, benzimidazole, polyimide, polyamideimide, polyimide, polyacetal, polyethylene, polypropylene, acrylic resin, polyester, polysulfone, polyether, polyetherimide, polyethersulfone, polycarbonate, polystyrene, polyphenylene sulfide, polyetheretherketone, polyetherketone, polyarylethersulfone, polyphosphazene or polyphenylquinoxaline; partially fluorinated polymers, such as polystyrene grafted ethylene-tetrafluoroethylene copolymer, or polystyrene grafted polytetrafluoroethylene copolymer; sulfonimides, and the like.

More specifically, when the cation conductive material is a hydrogen ion cation conductive material, the polymer may include a cation exchange group selected from the group consisting of a sulfonic acid group, a carboxylic acid group, a phosphoric acid group, a phosphonic acid group, and derivatives thereof in a side chain. Specific examples of the cation conductive material may include: fluorine-based polymers comprising poly (perfluorosulfonic acid), poly (perfluorocarboxylic acid), copolymers of tetrafluoroethylene and fluorovinyl ether containing sulfonic acid groups, defluorinated sulfated polyetherketones or mixtures thereof; and hydrocarbon-based polymers including sulfonated polyimide (S-PI), sulfonated polyarylethersulfone (S-PAES), Sulfonated Polyetheretherketone (SPEEK), Sulfonated Polybenzimidazole (SPBI), sulfonated polysulfone (S-PSU), sulfonated polystyrene (S-PS), sulfonated polyphosphazene, and mixtures thereof, but the present invention is not limited thereto.

The anion conductive material is a polymer capable of transferring anions such as hydroxide ions, carbonate ions or bicarbonate ions, the anion conductive material is commercially available in the form of hydroxide or halide (typically chloride), and the anion conductive material can be used in industrial water purification, metal separation, catalytic processes, and the like.

As the anion conductive material, a polymer doped with a metal hydroxide can be generally used. Specifically, as the polymer doped with the metal hydroxide, poly (ether sulfone), polystyrene, vinyl polymer, poly (vinyl chloride), poly (vinylidene fluoride), poly (tetrafluoroethylene), poly (benzimidazole), poly (ethylene glycol), or the like can be used.

In another aspect, the ion exchange membrane includes a first ion conducting material on one surface of the porous support and a second ion conducting material on the other surface of the porous support.

Here, the first ion-conducting material and the second ion-conducting material are polymers including hydrophilic repeating units and hydrophobic repeating units, and the first ion-conducting material and the second ion-conducting material may have different molar ratios of the hydrophilic repeating units to the hydrophobic repeating units.

At least one monomer constituting the hydrophilic repeating unit is substituted with an ion exchange group, and a monomer constituting the hydrophobic repeating unit may not be substituted with an ion exchange group, or may be substituted with a smaller number of ion exchange groups than the hydrophilic repeating unit. In addition, although all of the monomers constituting the hydrophilic repeating unit may also include an ion exchange group, the hydrophilic repeating unit may be composed of a monomer substituted with an ion exchange group and a monomer not substituted with an ion exchange group.

The first ion-conducting material and the second ion-conducting material may be a random copolymer in which a hydrophilic repeating unit and a hydrophobic repeating unit are randomly connected to each other, or a block copolymer including a hydrophilic block composed of the hydrophilic repeating unit and a hydrophobic block composed of the hydrophobic repeating unit.

more specifically, the first ion conductive material and the second ion conductive material may each independently be a hydrophilic repeating unit including a monomer represented by the following chemical formula 2.

[ chemical formula 2]

In the above chemical formula 2, R¹¹¹To R¹¹⁴、R¹²¹To R¹²⁴、R¹³¹To R¹³⁴And R¹⁴¹To R¹⁴⁴May each independently be selected from hydrogen atom, halogenAn elemental atom, an ion exchange group (ion conductive group), an electron donating group, and an electron withdrawing group.

The halogen atom may be any one selected from the group consisting of bromine, fluorine and chlorine.

The ion exchange group may be any one selected from the group consisting of a sulfonic acid group, a carboxylic acid group and a phosphoric acid group, and the cation exchange group may preferably be a sulfonic acid group. The ion exchange groups may be anion exchange groups, such as amine groups.

In addition, the electron donating group may be any one selected from the group consisting of an alkyl group, an allyl group, an aryl group, an amino group, a hydroxyl group, and an alkoxy group as an organic group for releasing electrons, and the electron withdrawing group may be any one selected from the group consisting of an alkylsulfonyl group, an acyl group, a haloalkyl group, an aldehyde group, a nitro group, a nitroso group, and a nitrile group as an organic group for withdrawing electrons.

The alkyl group may be methyl, ethyl, propyl, butyl, isobutyl, pentyl, hexyl, cyclohexyl, octyl, etc., and the haloalkyl group may be trifluoromethyl, pentafluoroethyl, perfluoroethyl, perfluoropropyl, perfluorobutyl, perfluoropentyl, perfluorohexyl, etc., and the allyl group may be propenyl, etc., and the aryl group may be phenyl, pentafluorophenyl, etc. Perfluoroalkyl refers to an alkyl group in which a portion or all of the hydrogen atoms are replaced with fluorine.

Z¹¹Is a divalent organic group which may be-O-or-S-, preferably-O-.

At this time, in the monomer represented by the above chemical formula 2, R in order to make the repeating unit including the monomer represented by the above chemical formula 2a hydrophilic repeating unit¹¹¹To R¹¹⁴、R¹²¹To R¹²⁴、R¹³¹To R¹³⁴And R¹⁴¹To R¹⁴⁴At least one of which may be an ion exchange group.

Specifically, the hydrophilic repeating unit may be represented by the following chemical formula 2-1 or chemical formula 2-2.

[ chemical formula 2-1]

In the above chemical formula 2-1, since R is p¹¹¹To R¹¹⁴、R¹²¹To R¹²⁴、R¹³¹To R¹³⁴、R¹⁴¹To R¹⁴⁴And Z¹¹The detailed description thereof is the same as above, and thus, a repetitive description will be omitted.

R²¹¹To R²¹⁴、R²²¹To R²²⁴And R²³¹To R²³⁴May each independently be selected from hydrogen atoms; a halogen atom; an electron donating group selected from the group consisting of alkyl, allyl, aryl, amino, hydroxyl, and alkoxy; and any one selected from the group consisting of an electron-withdrawing group selected from the group consisting of an alkylsulfonyl group, an acyl group, a haloalkyl group, an aldehyde group, a nitro group, a nitroso group, and a nitrile group. Since detailed description of the substituents is the same as above, repeated description will be omitted.

X²¹And X²²May each independently be a single bond or a divalent organic group. The divalent organic group is a divalent organic group which absorbs or releases electrons, and specifically, may be selected from the group consisting of-CO-, -SO₂-、-CONH-、-COO-、-CR’₂-、-C(CH₃)₂-、-C(CF₃)₂-and- (CH)₂)_n-any of the group consisting of. At this time, R' is any one selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group and a haloalkyl group, and n may be an integer of 1 to 10. When X is present²¹or X²²When it is a single bond, it means that phenyl groups present on both sides of X are directly linked, and as a representative example thereof, a biphenyl group may be included.

Z²¹Is a divalent organic group which may be-O-or-S-and is preferably-O-.

[ chemical formula 2-2]

In the above chemical formula 2-2, since R¹¹¹To R¹¹⁴、R¹²¹To R¹²⁴、R¹³¹To R¹³⁴、R¹⁴¹To R¹⁴⁴And Z¹¹The detailed description thereof is the same as above, and thus, a repetitive description will be omitted.

R³¹¹To R³¹⁴And R³²¹To R³²⁴May each independently be selected from hydrogen atoms; a halogen atom; ion exchange groups (ion conducting groups); an electron donating group selected from the group consisting of alkyl, allyl, aryl, amino, hydroxyl, and alkoxy; and any one selected from the group consisting of an electron-withdrawing group selected from the group consisting of an alkylsulfonyl group, an acyl group, a haloalkyl group, an aldehyde group, a nitro group, a nitroso group, and a nitrile group. Since the detailed description of the substituents is the same as above, the repeated description will be omitted.

X³¹May be selected from the group consisting of single bond, -CO-, -SO₂-、-CONH-、-COO-、-CR’₂-、-(CH₂)_n-, cyclohexylene having an ion exchange group, fluorenylene having an ion exchange group, C (CH)₃)₂-、-C(CF₃)₂-, -O-and-S-, R' may be any one selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group and a haloalkyl group, and n may be an integer of 1 to 10. Since the detailed description of the substituents is the same as above, the repeated description will be omitted.

However, the cyclohexylene group having an ion exchange group or the fluorenylene group having an ion exchange group means that hydrogen in the cyclohexylene group or the fluorenylene group is substituted with any one ion exchange group selected from the group consisting of a sulfonic acid group, a carboxyl group, a phosphoric acid group and a combination thereof.

Z³¹Is a divalent organic group, may be-O-or-S-, and is preferably-O-.

n³¹May be an integer of 0 to 10, and is preferably an integer of 0 or 1.

meanwhile, the first ion conductive material and the second ion conductive material may each independently have a hydrophobic repeating unit including a monomer represented by the following chemical formula 3.

[ chemical formula 3]

In the above chemical formula 3, since R is p²¹¹To R²¹⁴、R²²¹To R²²⁴、R²³¹To R²³⁴、X²¹、X²²And Z²¹The detailed description thereof is the same as above, and thus, a repetitive description will be omitted.

Specifically, the hydrophobic repeating unit may be represented by the following chemical formula 3-1.

[ chemical formula 3-1]

In the above chemical formula 3-1, since R is p²¹¹To R²¹⁴、R²²¹To R²²⁴、R²³¹To R²³⁴、X²¹、X²²And Z²¹The detailed description thereof is the same as above, and thus, a repetitive description will be omitted.

R⁴¹¹To R⁴¹⁴And R⁴²¹To R⁴²⁴May each independently be selected from hydrogen atoms; a halogen atom; an electron donating group selected from the group consisting of alkyl, allyl, aryl, amino, hydroxyl, and alkoxy; and any one selected from the group consisting of an electron-withdrawing group selected from the group consisting of an alkylsulfonyl group, an acyl group, a haloalkyl group, an aldehyde group, a nitro group, a nitroso group, and a nitrile group. Since the detailed description of the substituents is the same as above, the repeated description will be omitted.

X⁴¹May be selected from the group consisting of single bond, -CO-, -SO₂-、-CONH-、-COO-、-CR’₂-、-(CH₂)_n-, cyclohexylene, fluorenylene, -C (CH)₃)₂-、-C(CF₃)₂A divalent organic group of any one of the group consisting of-O-, and-S-,R' may be any one selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group and a haloalkyl group, and n may be an integer of 1 to 10. Since the detailed description of the substituents is the same as above, the repetitive description is omitted.

Z⁴¹Is a divalent organic group which may be-O-or-S-, preferably-O-.

n⁴¹May be an integer of 0 to 10, and is preferably an integer of 0 or 1.

In addition, the first ion conductive material and the second ion conductive material may each independently have a hydrophobic repeating unit including a monomer represented by the following chemical formula 4.

[ chemical formula 4]

In the above chemical formula 4, R⁵¹¹To R⁵¹³May each independently be selected from hydrogen atoms; a halogen atom; an electron donating group selected from the group consisting of alkyl, allyl, aryl, amino, hydroxyl, and alkoxy; and any one selected from the group consisting of an electron-withdrawing group selected from the group consisting of an alkylsulfonyl group, an acyl group, a haloalkyl group, an aldehyde group, a nitro group, a nitroso group, and a nitrile group. Since the detailed description of the substituents is the same as above, the repeated description will be omitted.

Z⁵¹Is a divalent organic group which may be-O-or-S-and is preferably-O-.

specifically, the hydrophobic repeating unit may be represented by the following chemical formula 4-1.

[ chemical formula 4-1]

In the above chemical formula 4-1, since R⁵¹¹To R⁵¹³And Z⁵¹the detailed description thereof is the same as above, and thus, a repetitive description will be omitted.

R⁶¹¹To R⁶¹⁴and R⁶²¹To R⁶²⁴May each independently be selected from hydrogen atoms; a halogen atom; an electron donating group selected from the group consisting of alkyl, allyl, aryl, amino, hydroxyl, and alkoxy; and any one selected from the group consisting of an electron-withdrawing group selected from the group consisting of an alkylsulfonyl group, an acyl group, a haloalkyl group, an aldehyde group, a nitro group, a nitroso group, and a nitrile group. Since the detailed description of the substituents is the same as above, the repeated description will be omitted.

X⁶¹May be selected from the group consisting of single bond, -CO-, -SO₂-、-CONH-、-COO-、-CR’₂-、-(CH₂)_n-, cyclohexylene, fluorenylene, -C (CH)₃)₂-、-C(CF₃)₂-, -O-and-S-, R' may be any one selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group and a haloalkyl group, and n may be an integer of 1 to 10. Since the detailed description of the substituents is the same as above, the repetitive description is omitted.

Z⁶¹Each independently is a divalent organic group which may be-O-or-S-, preferably-O-.

n⁶¹May be an integer of 0 to 10, preferably an integer of 0 or 1.

Meanwhile, the first ion conductive material and the second ion conductive material may each independently have a hydrophobic repeating unit represented by the following chemical formula 5-1.

[ chemical formula 5-1]

In the above chemical formula 5-1, since R is p³¹¹To R³¹⁴、R³²¹To R³²⁴、R⁴¹¹To R⁴¹⁴、R⁴²¹To R⁴²⁴、X³¹、X⁴¹、Z³¹、Z⁴¹、n³¹And n⁴¹The detailed description thereof is the same as described above, and thus, a repetitive description will be omitted. However, at this time X³¹And X⁴¹May be different from each other.

In order for the repeating units represented by the above chemical formula 3-1, chemical formula 4-1 and chemical formula 5-1 to be hydrophobic repeating units, among the repeating units represented by the above chemical formula 3-1, chemical formula 4-1 and chemical formula 5-1, preferably, R is²¹¹To R²¹⁴、R²²¹To R²²⁴、R²³¹To R²³⁴、R³¹¹To R³¹⁴、R³²¹To R³²⁴、R⁴¹¹To R⁴¹⁴、R⁴²¹To R⁴²⁴、R⁵¹¹To R⁵¹³、R⁶¹¹To R⁶¹⁴And R⁶²¹To R⁶²⁴Substantially no ion exchange groups are included. Herein, the meaning of substantially not including ion exchange groups means that the substituent may also include a small amount of ion exchange groups, but in an amount insufficient to interfere with phase separation between the hydrophilic region and the hydrophobic region.

Meanwhile, the first ion-conductive material and the second ion-conductive material may each independently have a hydrophilic repeating unit or a hydrophobic repeating unit further including a monomer represented by the following chemical formula 6.

When the first ion-conducting material or the second ion-conducting material further includes the monomer represented by the above chemical formula 6, the first ion-conducting material or the second ion-conducting material includes a nitrogen-containing aromatic ring group in the main chain to improve durability against radical attack and acid-base interaction. Therefore, in the first ion conductive material or the second ion conductive material, no addition reaction occurs in the aromatic ring of the ion exchange membrane, or no breakage of the aromatic ring occurs during the operation of the fuel cell due to the attack of the radicals formed on the cathode side, and the function of the ion exchange group is maximized, thereby improving the operation performance of the fuel cell in a low humidity state.

[ chemical formula 6]

In the above chemical formula 6, Z may be-O-or-S-, preferably-O-.

Y is a divalent nitrogen-containing aromatic ring group. A nitrogen-containing aromatic ring group means that at least one nitrogen atom is contained as a heteroatom in an aromatic ring. In addition to the nitrogen atom, another hetero atom may include an oxygen atom, a sulfur atom, and the like.

Specifically, the divalent nitrogen-containing aromatic ring group may be a divalent group of any nitrogen-containing aromatic ring compound selected from the group consisting of pyrrole, thiazole, isothiazole, oxazole, isoxazole, imidazole, imidazoline, imidazolidine, pyrazole, triazine, pyridine, pyrimidine, pyridazine, pyrazine, indole, quinoline, isoquinoline, tetrazole, tetrazine, triazole, carbazole, quinoxaline, quinazoline, indolizine, isoindole, indazole, phthalazine, naphthyridine, bipyridine, benzimidazole, imidazole, pyrrolidine, pyrroline, pyrazoline, pyrazolidine, piperidine, piperazine, and indoline.

The first and second ionically conductive materials may have a weight average molecular weight of 10,000 to 1,000,000g/mol, and preferably 100,000 to 500,000 g/mol. When the weight average molecular weight of the first ion-conductive material and the second ion-conductive material is less than 100,000g/mol, it is difficult to form a uniform film and durability may be deteriorated. When the weight average molecular weight of the first ion-conductive material and the second ion-conductive material is more than 500,000g/mol, the solubility may be decreased.

When the first ion-conducting material and the second ion-conducting material are hydrocarbon-based copolymers composed of hydrophilic repeating units and hydrophobic repeating units as described above, it is preferable that a hydrocarbon-based porous support is used as the porous support in terms of stability of the ion-exchange membrane. In particular, when the porous support and the ion conductive material having different properties are combined, for example, when the fluorine-based porous support and the hydrocarbon-based ion conductive material are combined, the ion conductive material may be easily separated or released from the porous support, or otherwise the impregnation property may be deteriorated.

The first ion conductive material and the second ion conductive material may be prepared by separately preparing a hydrophilic repeating unit and a hydrophobic repeating unit, and then performing a nucleophilic substitution reaction of the hydrophilic repeating unit and the hydrophobic repeating unit.

Furthermore, hydrophilic and hydrophobic repeat units can be prepared by nucleophilic substitution reactions. For example, when the hydrophilic repeating unit is a repeating unit represented by the above chemical formula 2-2, the hydrophilic repeating unit may be prepared by aromatic nucleophilic substitution reaction of the active dihalide monomer and the dihydride monomer constituting the two components of the repeating unit represented by the above chemical formula 2-2. In addition, when the hydrophobic repeating unit is a repeating unit represented by the above chemical formula 3-1, the hydrophobic repeating unit may be prepared by aromatic nucleophilic substitution reaction of the active dihalide monomer and the dihydride monomer constituting the two components of the repeating unit represented by the above chemical formula 3-1.

For example, when the hydrophilic repeating unit is a repeating unit represented by the above chemical formula 2-2, the hydrophilic repeating unit may be prepared by nucleophilic substitution reaction of an active dihalide monomer such as sulfonated dichlorodiphenyl sulfone (sddps), sulfonated difluorodiphenyl sulfone (SDFDPS), sulfonated dichlorobenzophenone (sddpk), dichlorodiphenyl sulfone (DCDPSs), difluorodiphenyl sulfone or bis- (4-fluorophenyl) sulfone (dps df) or dichlorobenzophenone (DCDPK), and an active dihalide monomer such as sulfonated 9,9 '-bis (4-hydroxyphenyl) fluorine or sulfonated 4, 4' - (9-fluorenylbisphenol) (SHPF) or 9,9 '-bis (4-hydroxyphenyl) fluorine or 4, 4' - (9-fluorenylbisphenol) (HPF).

When the hydrophobic repeating unit is a repeating unit represented by the above chemical formula 3-1, the hydrophobic repeating unit may be prepared by a nucleophilic substitution reaction of an active dihalide monomer such as 1, 3-bis (4-fluorobenzoyl) benzene, and an active dihydroxy compound monomer such as dihydroxydiphenylsulfone (DHDPS), dihydroxybenzophenone (dihydroxydiphenylketone) or dihydroxybenzophenone (DHDPK), or 4, 4' -Biphenol (BP).

When the hydrophobic repeating unit is a repeating unit represented by the above chemical formula 4-1, the hydrophobic repeating unit may be prepared by a nucleophilic substitution reaction of an active dihalide monomer such as 2, 6-difluorobenzonitrile and an active dihydroxide monomer such as dihydroxydiphenylsulfone (DHDPS), dihydroxybenzophenone (dihydroxydiphenylketone) or dihydroxybenzophenone (DHDPK), or 4, 4' -Biphenol (BP).

Similarly, even if the prepared hydrophilic repeating unit and hydrophobic repeating unit are subjected to nucleophilic substitution reaction, both ends of the hydrophilic repeating unit are adjusted to hydroxyl groups and both ends of the hydrophobic repeating unit are adjusted to halogen groups, or both ends of the hydrophobic repeating unit are adjusted to hydroxyl groups and both ends of the hydrophilic repeating unit are adjusted to halogen groups, whereby the hydrophilic repeating unit and the hydrophobic repeating unit can be subjected to nucleophilic substitution reaction.

At this time, the nucleophilic substitution reaction may be preferably carried out in the presence of a basic compound. Specifically, the basic compound may be sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium hydrogencarbonate, or the like, and may be used alone or in combination of two or more thereof.

Alternatively, the nucleophilic substitution reaction may be carried out in a solvent. At this time, specifically, the solvent may include an aprotic polar solvent such as N, N-dimethylacetamide, N-dimethylformamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, sulfolane, 1, 3-dimethyl-2-imidazolidinone, or the like, and may be used alone or in combination of two or more thereof.

At this time, in addition to the aprotic polar solvent, a solvent such as benzene, toluene, xylene, hexane, cyclohexane, octane, chlorobenzene, dioxane, tetrahydrofuran, anisole, phenetole, or the like may coexist.

Optionally, the method may further comprise introducing ion exchange groups into the first ion conducting material and the second ion conducting material. For example, when the ion exchange group is a sulfonic acid group as a cation exchange group, the following two methods can be exemplified as the introduction of the ion exchange group into the ion conductive material.

First, when hydrophilic repeating units of the first ion-conductive material and the second ion-conductive material are prepared, there is a method of introducing ion exchange groups into a polymer prepared by polymerization using a monomer containing an ion exchange group. In this case, as a monomer for nucleophilic substitution reaction, sulfonated dichlorodiphenyl sulfone (sddps), sulfonated difluorodiphenyl sulfone (SDFDPS), sulfonated dichlorobenzophenone (SDCDPK), or sulfonated 9,9 '-bis (4-hydroxyphenyl) fluorine or sulfonated 4, 4' - (9-fluorenylbisphenol) (SHPF) including an ion exchange group may be used.

In this case, a method of preparing a polymer having a sulfonate group by reacting with a monomer having a sulfonate group instead of a sulfonic acid group and then converting the sulfonate group into a sulfonic acid group may also be used.

Second, ion exchange groups can be introduced into hydrophilic repeat units by preparing a polymer using monomers that do not contain ion exchange groups and sulfonating the polymer using a sulfonating agent.

Sulfuric acid may be used as the sulfonating agent, but in another example, the prepared polymer is reacted in a chlorinated solvent such as dichloromethane, chloroform and 1, 2-dichloroethane in the presence of a large amount of chlorosulfonic acid (1 to 10 times based on the total weight of the polymer, preferably 4 to 7 times based on the total weight of the polymer) to prepare an ion conductive material having hydrogen ion conductivity.

When the first ion conductive material and the second ion conductive material include a sulfonic acid group as an ion exchange group, the ion conductive material may have a sulfonation degree of 1 mol% to 100 mol%, preferably 50 mol% to 100 mol%. That is, the ion conductive material may be sulfonated by 100 mol% at a site that may be sulfonated, and even if the ion conductive material is sulfonated by 100 mol%, the dimensional stability and durability of the ion conductive material are not deteriorated due to the structure of the block copolymer of the ion conductive material. In addition, when the sulfonation degree of the ion conductive material is within the above range, excellent ion conductivity can be exhibited without deterioration in dimensional stability.

When the first ion conductive material and the second ion conductive material include the hydrophilic repeating unit and the hydrophobic repeating unit, first, the hydrophilic repeating unit and the hydrophobic repeating unit are synthesized in an oligomer state, and then, the hydrophilic repeating unit and the hydrophobic repeating unit are synthesized to have a desired molar ratio, so that the structure can be easily controlled and the characteristics as the ion conductive material can be easily controlled. Due to microphase separation of the hydrophilic repeating units and the hydrophobic repeating units, the structurally controlled ion-conductive material can provide an ion-conductive material having improved ion conductivity and durability over the entire humidification range.

In this case, the molar ratio of the hydrophilic repeating unit to the hydrophobic repeating unit means the number of moles of the hydrophobic repeating unit per 1 mole of the hydrophilic repeating unit contained in the first ion-conductive material or the second ion-conductive material. The first ion conducting material and the second ion conducting material may each independently have a molar ratio of hydrophilic repeat units to hydrophobic repeat units of 1:0.5 to 1:10, specifically 1:1 to 1:5, more specifically 1: higher than 1.2 to 1: 5. If the molar ratio of the hydrophobic repeating units is less than 0.5, the water content may increase and the dimensional stability and durability may deteriorate. If the molar ratio of the hydrophobic repeating units is more than 10, ion conductive properties may not be exhibited.

Since the first ion-conductive material and the second ion-conductive material are composed of different repeating units, the molar ratios of the hydrophilic repeating unit and the hydrophobic repeating unit may be different from each other, and even when the first ion-conductive material and the second ion-conductive material are composed of the same repeating unit, the molar ratios of the hydrophilic repeating unit and the hydrophobic repeating unit may be different from each other. That is, the property of the first ion-conductive material and the second ion-conductive material to exhibit performance may be adjusted differently by making the molar ratios of the hydrophilic repeating unit and the hydrophobic repeating unit different from each other.

At this time, the first ion-conductive material may be an ion-conductive material in which a molar ratio of the hydrophilic repeating unit to the hydrophobic repeating unit is higher than that of the second ion-conductive material.

Specifically, the molar ratio of the hydrophilic repeating unit to the hydrophobic repeating unit in the first ion-conductive material may be 1:2 to 1:5, specifically 1:2 to 1:3, and the molar ratio of the hydrophilic repeating unit to the hydrophobic repeating unit in the second ion-conductive material may be 1:3 to 1:6, specifically 1:3 to 1: 4. At this time, even if the ranges of the molar ratios of the hydrophilic repeating units to the hydrophobic repeating units in the first ion-conductive material and the second ion-conductive material overlap, the molar ratio of the hydrophilic repeating units to the hydrophobic repeating units in the first ion-conductive material may be higher than the molar ratio of the hydrophilic repeating units to the hydrophobic repeating units in the second ion-conductive material.

That is, when the ion-exchange membrane is manufactured using the same ion-conductive material having a relatively high molar ratio of hydrophilic repeating units as the first ion conductor, there is an advantage of exhibiting high ion-conductive efficiency and improving the voltage efficiency (V.E) of the energy storage system.

When an ion-exchange membrane is produced using the same ion-conductive material as the second ion-conductive material, which has a relatively high molar ratio of hydrophobic repeating units, the swelling property of the ion-exchange membrane can be reduced while ensuring the morphological stability and durability of the ion-exchange membrane itself. In addition, when the hydrophilic channel is formed relatively small to be applied to the redox flow battery, the crossover of vanadium ions can be reduced, thereby improving current efficiency (C.E).

Therefore, by introducing the first ion-conductive material having a relatively high molar ratio of hydrophilic repeating units into one surface of the porous support, it is possible to improve ion-conductive properties and reduce film resistance, thereby improving performance efficiency of the energy storage system. In addition, by introducing the second ion conductive material having a relatively high molar ratio of hydrophobic repeating units into the other surface of the porous support, it is possible to ensure morphological stability of the ion exchange membrane and reduce crossover of vanadium ions, thereby ensuring durability of the ion exchange membrane.

Meanwhile, in particular, the first ion-conductive material located on one surface of the porous support and the second ion-conductive material located on the other surface of the porous support may be present in the form of a first ion-conductive layer located on one surface of the porous support and a second ion-conductive layer located on the other surface of the porous support.

In this case, the pores of the porous support may be filled with any one selected from the group consisting of the first ion-conductive material, the second ion-conductive material, and a combination thereof. That is, the pores of the porous support may be filled with only the first ion-conductive material and may be filled with only the second ion-conductive material, and the pores on one surface of the porous support, on which the first ion-conductive layer is formed, may be filled with the first ion-conductive material and the pores on the other surface of the porous support, on which the second ion-conductive layer is formed, may also be filled with the second ion-conductive material.

Fig. 1 is a sectional view schematically showing an example of an ion exchange membrane 1.

Referring to fig. 1, a first ion-conductive material 20 is filled in pores on one surface of a porous support 10, and a second ion-conductive material 30 is filled in pores on the other surface of the porous support 10.

The ion exchange membrane 1 may further include a first ion conductive layer 21 and a second ion conductive layer 31 on one surface and the other surface of the porous support 10, respectively. The first ion-conductive layer 21 and the second ion-conductive layer 31 may be formed using an ion-conductive material remaining after filling the first ion-conductive material 20 and the second ion-conductive material 30 into the pores of the porous support 10 to form a thin film on the surface of the porous support 10.

The thickness ratio of the first ion-conductive layer 21 may be 10 to 200 length%, specifically 50 to 100 length%, with respect to the total thickness of the porous support, and the thickness ratio of the second ion-conductive layer 31 may be 10 to 200 length%, specifically 50 to 100 length%, with respect to the total thickness of the porous support. If the thickness ratio of the first ion-conductive layer 21 to the second ion-conductive layer 31 is less than 10% by length, ion-conductive properties may not be exhibited, and if the thickness ratio of the first ion-conductive layer 21 to the second ion-conductive layer 31 is greater than 200% by length, a porous support cannot be used as a support, and durability may be reduced similarly to a single membrane. The thickness ratio of the ion-conductive layer on one surface can be calculated by the following formula 2.

[ formula 2]

The thickness ratio (% by length) of the ion-conductive layer on one surface is (thickness of the ion-conductive layer on one surface/thickness of the porous support) x 100

When considering the effects obtained by introducing the first ion-conducting material 20 and the second ion-conducting material 30, the thickness ratio of the first ion-conducting material 20 to the second ion-conducting material 30 may be 9:1 to 1:9, specifically 9:1 to 6:4, more specifically 8:2 to 6:4, with respect to the total thickness of the ion-exchange membrane 1.

That is, in order to obtain morphological stability of the ion-exchange membrane 1 while improving the ion-conductive performance of the ion-exchange membrane 1, it is advantageous that the thickness of the first ion-conductive material 20 having a relatively high molar ratio of hydrophilic repeating units is greater than the thickness of the second ion-conductive material 30.

Here, the thickness of the first ion-conductive material 20 is given by the sum of the thickness of the first ion-conductive material 20 impregnated in the internal pores of the porous support body 10 and the thickness of the first ion-conductive layer 21. Similarly, the thickness of the second ion-conductive material 30 is given by the sum of the thickness of the second ion-conductive material 30 impregnated in the internal pores of the porous support body 10 and the thickness of the second ion-conductive layer 31.

When considering the effect obtained by introducing the first ion-conductive material 20 and the second ion-conductive material 30, the first ion-conductive material 20 is filled in all the pores of the porous support body 10, the first ion-conductive layer 21 may be formed on one surface of the porous support body 10, and the second ion-conductive layer 31 may be formed on the other surface of the porous support body 10.

The ion exchange membrane 1 may be formed by laminating a plurality of porous supports 10 including the first ion conductive material 20 and the second ion conductive material 30.

Fig. 2 and 3 are cross-sectional views schematically showing an ion exchange membrane 1 in which a plurality of porous supports 10 are laminated.

Referring to fig. 2 and 3, ion exchange membrane 1 may be configured by laminating first ion conductive material 20-1 or second ion conductive material 30-1 of first porous support 10-1 to face first ion conductive material 20-2 or second ion conductive material 30-2 of second porous support 10-2. Specifically, in FIG. 2, first ionically conductive material 20-1 of first porous support 10-1 is shown laminated to first ionically conductive material 20-2 facing second porous support 10-2, and in FIG. 3, second ionically conductive material 30-1 of first porous support 10-1 is shown laminated to first ionically conductive material 20-2 facing second porous support 10-2.

A method of manufacturing an ion exchange membrane according to another embodiment of the present invention includes: preparing a porous support comprising a plurality of pores; forming a first ion-conducting material on one surface of a porous support; and forming a second ion-conducting material on the other surface of the porous support.

First, a porous support including a plurality of pores, a first ion-conductive material, and a second ion-conductive material is prepared.

At this time, the first ion-conducting material and the second ion-conducting material are polymers including hydrophilic repeating units and hydrophobic repeating units, and the first ion-conducting material and the second ion-conducting material may have different molar ratios of the hydrophilic repeating units to the hydrophobic repeating units. Since the description of the porous support, the first ion-conductive material, and the second ion-conductive material is the same as described above, a repetitive description will be omitted.

Next, a first ion-conductive material is formed on one surface of the porous support, and a second ion-conductive material is formed on the other surface of the porous support, to manufacture an ion-exchange membrane in the form of a reinforced composite membrane.

Specifically, the first ion-conductive material is filled in the pores on one surface of the porous support, and the first ion-conductive material remaining after filling the pores on one surface of the porous support forms the first ion-conductive layer on one surface of the porous support. In addition, the second ion-conductive material is filled in the pores on the other surface of the porous support, and the second ion-conductive material remaining after filling the pores on the other surface of the porous support forms a second ion-conductive layer on the other surface of the porous support.

However, the present invention is not limited thereto, and the pores of the porous support may be filled with only the first ion-conductive material to form the first ion-conductive layer, and then only the second ion-conductive layer is formed on the other surface of the porous support with the second ion-conductive material, or vice versa.

The filling of the pores of the porous support with the first ion-conducting material and the second ion-conducting material may generally be performed by carrying or immersing the porous support in a solution containing the first ion-conducting material or the second ion-conducting material. In addition, the filling of the pores of the porous support with the first and second ion-conductive materials may also be performed by any one method selected from the group consisting of bar coating, comma coating (comma coating), slit die, screen printing, spray coating, blade coating, lamination, and combinations thereof.

That is, the manufacturing method of the ion exchange membrane may use the existing process as it is, except that the first ion conductive material and the second ion conductive material are filled in one surface and the other surface of the porous support body, respectively.

The first ion-conducting material and the second ion-conducting material may be filled in the porous support in the form of a solution or dispersion containing the first ion-conducting material and the second ion-conducting material. The solution or dispersion containing the first ion-conducting material or the second ion-conducting material may be used by purchasing a commercially available solution or dispersion of the ion-conducting material, or may be prepared by dispersing the first ion-conducting material or the second ion-conducting material in a solvent. Since the method of dispersing the first ion-conductive material or the second ion-conductive material in the solvent may be performed by a method well known in the art, a detailed description thereof will be omitted.

As the solvent used for preparing the solution or dispersion containing the first ion-conductive material or the second ion-conductive material, a solvent selected from the group consisting of water, a hydrophilic solvent, an organic solvent, and a mixture of at least one of them may be used.

The hydrophilic solvent may have at least one functional group selected from the group consisting of alcohols, isopropyl alcohol, ketones, aldehydes, carbonates, carboxylates, carboxylic acids, ethers, and amides including a linear or branched saturated or unsaturated hydrocarbon having 1 to 12 carbon atoms as a main chain, and the at least one functional group may include an alicyclic or aromatic cyclic compound as at least a part of the main chain.

The organic solvent may be selected from the group consisting of N-methylpyrrolidone, dimethylsulfoxide, tetrahydrofuran, and mixtures thereof.

In addition, filling the pores of the porous support with the first ion-conductive material or the second ion-conductive material may be affected by various factors such as temperature, time, and the like. For example, the filling of the pores of the porous support with the first ion-conducting material or the second ion-conducting material may be affected by the thickness of the porous support, the concentration of a solution or dispersion containing the first ion-conducting material or the second ion-conducting material, the type of solvent, and the like. However, the process may be performed at any point of the solvent at a temperature of 100 ℃ or less, and more generally, may be performed at a temperature of room temperature (20 ℃) to 70 ℃ or less for about 5 to 30 minutes. However, the temperature may not be equal to or higher than the melting point of the porous support.

Meanwhile, the method for manufacturing the ion exchange membrane may further include: a plurality of porous supports including a first ion conductive material and a second ion conductive material are prepared, and the plurality of porous supports are laminated.

The lamination method can be applied when applying a plurality of porous supports, and the thickness ratio required in the energy storage system can be easily adjusted by laminating the porous supports, while an ion exchange membrane having high efficiency can be manufactured.

An energy storage system according to yet another embodiment of the invention includes an ion exchange membrane. Hereinafter, a case where the energy storage system is a redox flow battery or a fuel cell will be described in detail. However, the present invention is not limited thereto, and the ion exchange membrane may also be applied to a secondary battery type energy storage system.

In one example of the energy storage system, since the ion exchange membrane has low vanadium ion permeability due to blocking vanadium ions by a small ion channel, it is possible to solve the problem of deterioration of energy efficiency due to crossing of vanadium active materials when applied to a vanadium redox flow battery, thereby achieving high energy efficiency. As a result, the energy storage system may be a redox flow battery.

The redox flow battery may be charged and discharged by supplying a catholyte and an anolyte to a battery cell including a cathode and an anode arranged to face each other and an ion exchange membrane disposed between the cathode and the anode.

The redox flow battery may include: an all vanadium based redox cell using a V (IV)/V (V) redox couple (couple) as a catholyte and a V (II)/V (III) redox couple as an anolyte; a vanadium-based redox cell using a halogen redox couple as a catholyte and a v (ii)/v (iii) redox couple as an anolyte; a polysulfide bromine redox cell using a halogen redox couple as a cathode electrolyte and a sulfide redox couple as an anode electrolyte; or a zinc-bromine (Zn-Br) redox cell using a halogen redox couple as a cathode electrolyte and a zinc (Zn) redox couple as an anode electrolyte, but in the present invention, the type of redox flow cell is not limited.

Hereinafter, description will be made taking a case where the redox flow battery is an all-vanadium-based redox battery as an example. However, the redox flow battery of the present invention is not limited to the all-vanadium-based redox battery.

Fig. 4 is a schematic diagram showing an all vanadium-based redox cell.

Referring to fig. 4, the redox flow battery includes: a battery case 102; an ion exchange membrane 104 installed to divide the cell case 102 into a cathode cell 102A and an anode cell 102B; and a cathode 106 and an anode 108 in the cathode cell 102A and the anode cell 102B, respectively.

In addition, the redox flow battery may further include a catholyte storage tank 110 that stores catholyte and an anolyte storage tank 112 that stores anolyte.

The redox flow battery includes a catholyte inlet and a catholyte outlet at the upper and lower ends of the cathode cell 102A, and the redox flow battery may include an anolyte inlet and an anolyte outlet at the upper and lower ends of the anode cell 102B.

The catholyte stored in the catholyte storage tank 110 is introduced into the cathode cell 102A via a catholyte inlet by the pump 114 and then discharged from the cathode cell 102A via a catholyte outlet.

Similarly, anolyte stored in the anolyte storage tank 112 is introduced into the anode cell 102B via an anolyte inlet by the pump 116, and then discharged from the anode cell 102B via an anolyte outlet.

In the cathode cell 102A, electrons move through the cathode 106 in response to operation of the power/load 118, thereby causingOxidation/reduction reaction of (1). Similarly, in the anode cell 102B, electrons move through the anode 108 in response to operation of the power/load 118, thereby causingOxidation/reduction reaction of (1). After the oxidation/reduction reaction, the catholyte and anolyte are recycled to catholyte storage tank 110 and anolyte storage tank 112, respectively.

The cathode 106 and the anode 108 may be formed of any one selected from the group consisting of: at least one metal selected from the group consisting of Ru, Ti, Ir, Mn, Pd, Au and Pt; an oxide of at least one metal selected from Ru, Ti, Ir, Mn, Pd, Au, and Pt (for example, Ir oxide or Ru oxide applied on a Ti substrate); a carbon composite comprising the composite material; a Dimensionally Stable Electrode (DSE) comprising a composite material; a conductive polymer (e.g., a conductive polymer material such as polyacetylene or polythiophene); graphite; glassy carbon; a conductive diamond; conductive diamond-like carbon (DLC); a nonwoven made of carbon fibers; and woven fabrics made of carbon fibers.

The catholyte and the anolyte may include any one metal ion selected from the group consisting of titanium ions, vanadium ions, chromium ions, zinc ions, tin ions, and mixtures thereof.

For example, the anolyte comprises vanadium divalent ions (V)²⁺) Or vanadium trivalent ion (V)³⁺) As the anolyte ions, and the catholyte may contain vanadium tetravalent ions (V)⁴⁺) Or a vanadium pentavalent ion (V)⁵⁺) As catholyte ions.

The concentration of the metal ions contained in the catholyte and the anolyte is preferably 0.3M to 5M.

As the solvent for the catholyte and the anolyte, a solvent selected from the group consisting of H and H may be used₂SO₄、K₂SO₄、Na₂SO₄、H₃PO₄、H₄P₂O₇、K₂PO₄、Na₃PO₄、K₃PO₄、HNO₃、KNO₃And NaNO₃Any one of the group consisting of. Since metal ions to be a cathode active material and an anode active material are both water-soluble, the aqueous solution can be suitably used as a solvent for a cathode electrolyte and an anode electrolyte. In particular, when any one selected from the group consisting of sulfuric acid, phosphoric acid, nitric acid, sulfate, phosphate, and nitrate is used as the aqueous solution, the stability, reactivity, and solubility of the metal ions may be improved.

Meanwhile, the ion exchange membrane can also be applied to a membrane electrode assembly for a fuel cell. Specifically, the membrane electrode assembly may include an anode and a cathode facing each other, and an ion exchange membrane disposed between the anode and the cathode.

Modes for carrying out the invention

Hereinafter, examples of the present invention will be described in detail so as to be easily implemented by those skilled in the art. The invention may, however, be embodied in many different forms and is not limited to the examples described herein.

[ preparation example 1: preparation of ion-conductive Material

Preparation examples 1 to 1

1) Preparation of hydrophobic repeat units

as shown in the following reaction formula 3, bisphenol a and 1, 3-bis (4-fluorobenzoyl) benzene were reacted in the presence of potassium carbonate using a DMAc/toluene cosolvent at 160 ℃ to 180 ℃ for 30 hours, sprayed and washed with purified water, and then dried with hot air. At this time, the polymerization degree of the oligomer was adjusted using the caroth equation.

[ reaction formula 3]

2) Preparation of hydrophilic repeating units

As shown in the following reaction formula 4, 4' - (9-fluorenylidene) diphenol and bis (4-fluorophenyl) sulfone are reacted in the presence of potassium carbonate using DMAc/toluene cosolvent at 160 to 180 ℃ for 30 hours, sprayed and washed with purified water, and then dried with hot air. At this time, the polymerization degree of the oligomer was adjusted using the caroth equation.

[ reaction formula 4]

3) Preparation of polymers

the prepared hydrophilic repeating unit and hydrophobic repeating unit were reacted at 160 to 180 ℃ for 30 hours using DMAc/toluene co-solvent in the presence of potassium carbonate, sprayed and washed with purified water, and then dried with hot air. The molar ratio of hydrophilic repeat units to hydrophobic repeat units of the prepared polymer was 1: 3.5.

4) Preparation of ion-conducting materials

The prepared polymer was dissolved in dichloromethane and slowly added to a 5-fold excess of chlorosulfonic acid/DCM solution, followed by stirring for 24 hours. The solution was discarded and the precipitated solid was washed with purified water and then dried with hot air.

Preparation examples 1 to 2

An ion conductive material was prepared in the same manner as in preparation example 1-1 above, except that the polymer was prepared to have a molar ratio of hydrophilic repeating units to hydrophobic repeating units of 1:2.5 when the polymer was prepared in preparation example 1-1 above.

Preparation examples 1 to 3

1) Preparation of hydrophobic repeat units

As shown in the following reaction formula 5, 4, 4' -dihydroxybenzophenone and 2, 6-difluorodicarbonitrile were reacted in the presence of potassium carbonate using DMAc/toluene cosolvent at 160 ℃ to 180 ℃ for 30 hours, sprayed and washed with purified water, and then dried with hot air. At this time, the polymerization degree of the oligomer was adjusted using the caroth equation.

[ reaction formula 5]

2) Preparation of hydrophilic repeating units

As shown in the following reaction formula 6, 4, 4' - (9-fluorenylidene) diphenol and bis (4-fluorophenyl) sulfone are reacted in the presence of potassium carbonate using DMAc/toluene cosolvent at 160 to 180 ℃ for 30 hours, sprayed and washed with purified water, and then dried with hot air. At this time, the polymerization degree of the oligomer was adjusted using the caroth equation.

[ reaction formula 6]

3) Preparation of polymers

The prepared hydrophilic repeating unit and hydrophobic repeating unit were reacted at 160 to 180 ℃ for 30 hours using DMAc/toluene co-solvent in the presence of potassium carbonate, sprayed and washed with purified water, and then dried with hot air. The molar ratio of the hydrophilic repeating unit (Y) to the hydrophobic repeating unit (X) of the prepared polymer was 1: 3.5.

4) Preparation of ion-conducting materials

The prepared polymer was dissolved in dichloromethane and slowly added to a 5-fold excess of chlorosulfonic acid/DCM solution, followed by stirring for 24 hours. The solution was discarded and the precipitated solid was washed with purified water and then dried with hot air.

Preparation examples 1 to 4

An ion conductive material was prepared in the same manner as in preparation examples 1 to 3 above, except that the polymer was prepared to have a molar ratio of hydrophilic repeating units to hydrophobic repeating units of 1:2.5 when the polymer was prepared in preparation examples 1 to 3 above.

Preparation examples 1 to 5

1) Preparation of hydrophobic repeat units

4, 4' -dihydroxybenzophenone was reacted with bis (4-fluorophenyl) sulfone in the presence of potassium carbonate using DMAc/toluene cosolvent at 160 ℃ to 180 ℃ for 30 hours, sprayed and washed with purified water, and then dried with hot air. At this time, the polymerization degree of the oligomer was adjusted using the caroth equation.

2) Preparation of hydrophilic repeating units

4, 4' - (9-fluorenylidene) diphenol and 1, 3-bis (4-fluorobenzoyl) benzene were reacted in the presence of potassium carbonate using DMAc/toluene cosolvent at 160 ℃ to 180 ℃ for 30 hours, sprayed and washed with purified water, and then dried with hot air. At this time, the polymerization degree of the oligomer was adjusted using the caroth equation.

3) Preparation of polymers

The prepared hydrophilic repeating unit and hydrophobic repeating unit were reacted at 160 to 180 ℃ for 30 hours using a DMAc/toluene co-solvent in the presence of potassium carbonate, sprayed and washed with purified water, and then dried with hot air to prepare a polymer represented by the following chemical formula 7. The molar ratio of the hydrophilic repeating unit (Y) to the hydrophobic repeating unit (X) of the prepared polymer was 1: 3.5.

[ chemical formula 7]

4) Ion conductive materialPreparation of

The prepared polymer was dissolved in dichloromethane and slowly added to a 5-fold excess of chlorosulfonic acid/DCM solution, followed by stirring for 24 hours. The solution was discarded and the precipitated solid was washed with purified water and then dried with hot air.

Preparation examples 1 to 6

An ion conductive material was prepared in the same manner as in preparation examples 1 to 5 above, except that the polymer was prepared to have a molar ratio of hydrophilic repeating units to hydrophobic repeating units of 1:2.5 when the polymer was prepared in preparation examples 1 to 5 above.

[ preparation example 2: preparation of porous support

Preparation example 2-1

The polyamide acid was dissolved in dimethylformamide to prepare 5 liters of 480 poise spinning solution. The prepared spinning solution was transferred to a solution tank and supplied and rotated to a spinning chamber having 20 nozzles and applied to a high voltage of 3kV by a metering gear pump to prepare a nanofiber precursor web. At this time, the amount of the solution supplied was 1.5 ml/min. The nanofiber precursor web prepared was heat-treated at 350 ℃ to prepare a porous support (porosity: 40 vol%).

The weight per unit area of the polyimide nanofibers in the porous support was 6.8 gsm.

[ example 1: preparation of ion exchange membranes

[ EXAMPLES 1-1 ]

The ion-conductive material prepared in production example 1-1 and having a molar ratio of the hydrophilic repeating unit to the hydrophobic repeating unit of 1:3.5 and the ion-conductive material prepared in production example 1-2 and having a molar ratio of the hydrophilic repeating unit to the hydrophobic repeating unit of 1:2.5 were dissolved in DMAc in an amount of 20 wt%, respectively, to prepare an ion-conductive material solution.

Next, an ion exchange membrane was manufactured by impregnating the ion conductive material solutions prepared in preparation example 1-1 and preparation example 1-2 into one surface and the other surface of the porous support prepared in preparation example 2-1, respectively.

Specifically, in the impregnation method, first, the ion-conductive material prepared in preparation example 1-2 having a relatively high molar ratio of hydrophilic repeating units is impregnated into one surface of the porous support to fill in the pores on one surface of the porous support, and then the first ion-conductive layer is formed on one surface of the porous support. Thereafter, the ion-conductive material prepared in preparation example 1-1, which has a relatively high molar ratio of hydrophobic repeating units, was impregnated into the other surface of the porous support to fill in the pores on the other surface of the porous support, and then a second ion-conductive layer was formed on the other surface of the porous support.

Each surface was immersed for 30 minutes, then left under reduced pressure for 1 hour, and dried in vacuum at 80 ℃ for 10 hours to manufacture an ion exchange membrane.

at this time, the weight of the ion-conductive material was 65mg/cm². The thickness ratio of the first ion-conductive material prepared in preparation example 1-2 having a relatively high molar ratio of hydrophilic repeating units was 70%, and the thickness ratio of the second ion-conductive material prepared in preparation example 1-1 having a relatively high molar ratio of hydrophobic repeating units was 30%, relative to the entire ion-exchange membrane prepared. At this time, the thickness ratio is the sum of the thickness impregnated into the porous support and the thickness of the ion-conductive layer formed on the surface of the porous support.

(examples 1-2 and 1-3)

An ion exchange membrane was produced in the same manner as in example 1-1, except that the ion-conductive materials prepared in production examples 1-3 and production examples 1-4 and the ion-conductive materials prepared in production examples 1-5 and production examples 1-6 were used in example 1-1 instead of the ion-conductive materials prepared in production examples 1-1 and production examples 1-2.

Comparative example 1-1

The porous support prepared in preparation example 2-1 was immersed in an ion-conductive material solution prepared by dissolving the ion-conductive material prepared in preparation example 1-1 in DMAc in an amount of 20 wt% for 30 minutes twice, then left under reduced pressure for 1 hour, and dried in vacuum at 80 ℃ for 10 hours to produce ion exchangeAnd (3) a membrane. At this time, the weight of the ion-conductive material was 65mg/cm²。

Comparative examples 1 and 2

The porous support prepared in preparation example 2-1 was immersed in an ion-conductive material solution prepared by dissolving the ion-conductive material prepared in preparation example 1-2 in DMAc in an amount of 20 wt% for 30 minutes twice, then left under reduced pressure for 1 hour, and dried in vacuum at 80 ℃ for 10 hours to manufacture an ion-exchange membrane. At this time, the weight of the ion-conductive material was 65mg/cm²。

[ Experimental example 1: measurement of characteristics of prepared ion-conductive Material ]

The ion exchange membranes produced in comparative examples 1-1 and 1-2 were evaluated for their Ion Exchange Capacity (IEC) by neutralization titration. The ionic conductivity and the dimensional stability were measured under the conditions of 80 ℃ and 95% relative humidity and 80 ℃ and 50% relative humidity, respectively. The results are shown in table 1 below.

Using the apparatus shown in FIG. 5 below, by measuring 1M H₂SO₄the ionic conductivity was calculated from the membrane resistance in (1).

The membrane resistance was calculated by the following formula 3, and the effective area of the membrane was 0.75cm²。

[ formula 3]

Film resistance (R) ═ R₁－R₂) X (effective area of membrane)

Here, R is when implanting the film₁Is resistance [ omega ]]When the film is not implanted, R₂Is resistance [ omega ]]。

The ionic conductivity was calculated by the following formula 4.

[ formula 4]

Ionic conductivity (S/cm) ═ 1/R × t

Wherein R is a film resistance [ omega. cm ]²]And t is the film thickness [ cm ]]。

After the prepared ion exchange membrane was immersed in distilled water at 80 ℃ for 24 hours and the wet ion exchange membrane was taken out, the thickness and area of the ion exchange membrane were measured, after the ion exchange membrane was dried under vacuum at 80 ℃ for 24 hours, the thickness and area of the ion exchange membrane were measured,Then passing through the thickness T of the ion exchange membrane in a wet state_wetAnd area L_wetAnd thickness T of ion exchange membrane in dry state_dryAnd area L_drythe swelling ratio (swelling ratio) with respect to thickness and the swelling ratio with respect to area were measured by inputting in the following formulas 5 and 6, thereby measuring dimensional stability.

[ formula 5]

(T_wet－T_dry/T_dry) X 100. DELTA.T (swelling ratio relative to thickness,%)

[ formula 6]

(L_wet－L_dry/L_dry) X 100 ═ Δ L (swelling ratio with respect to area,%)

[ Table 1]

As shown in table 1 above, the ion-exchange membranes prepared in comparative examples 1-1 and 1-2 include an ion-conductive material having a hydrocarbon-based block copolymer composed of a hydrophilic repeating unit and a hydrophobic repeating unit so as to be structurally changed, and characteristics of the block copolymer and the ion-conductive material are easily controlled by controlling the structures of the hydrophilic repeating unit and the hydrophobic repeating unit.

When the characteristics are described in terms of control of the molar ratio of the hydrophilic repeating units to the hydrophobic repeating units of the ion-conductive material, it can be confirmed that the ion-conductive material having a relatively higher molar ratio of the hydrophilic repeating units at a molar ratio of 1:2.5 has a superior ion-exchange ability or ion-conductive property compared to the ion-conductive material having a relatively higher molar ratio of the hydrophobic repeating units at a molar ratio of 1: 3.5. These characteristics may help to improve the performance efficiency of the energy storage system. However, from the viewpoint of the water content, it can be confirmed that the ion conductive material having a relatively high molar ratio of the hydrophobic repeating unit is advantageous, and dimensional stability can be ensured and morphological stability is excellent even at the same film thickness.

In particular, swelling of the ion-exchange membrane is a factor greatly affecting durability, and since morphological stability is ensured, the durability of the ion-exchange membrane on the energy storage system is improved, thereby promoting improvement of the durability of the entire energy storage system.

[ Experimental example 2: morphological analysis of the prepared ion exchange Membrane

AFM images of one surface and the other surface of the ion exchange membrane prepared in example 1-1 are shown in fig. 6 and fig. 7, respectively.

Specifically, fig. 6 shows an AFM image of one surface impregnated with the ion-conductive material prepared in preparation example 1-1, which has a relatively high molar ratio of hydrophobic repeating units, wherein the molar ratio of hydrophilic repeating units to hydrophobic repeating units is 1: 3.5; fig. 7 shows an AFM image of one surface impregnated with the ion-conductive material prepared in preparation example 1-2, which has a relatively high molar ratio of hydrophilic repeating units, wherein the molar ratio of hydrophilic repeating units to hydrophobic repeating units is 1: 2.5.

Referring to fig. 6 and 7, the morphology of the ion conductive material having different molar ratios of the hydrophilic repeating unit to the hydrophobic repeating unit was observed, and as a result, it was confirmed that the structure of the ion conductive material could be controlled by controlling the molar ratio of the hydrophilic repeating unit to the hydrophobic repeating unit of the ion conductive material.

Specifically, when ion channel formation of the ion-conductive material having a relatively high molar ratio of the hydrophobic repeating unit in which the molar ratio of the hydrophilic repeating unit to the hydrophobic repeating unit is 1:3.5 and the ion-conductive material having a relatively high molar ratio of the hydrophilic repeating unit to the hydrophobic repeating unit in which the molar ratio of the hydrophilic repeating unit to the hydrophobic repeating unit is 1:2.5 are compared, it can be confirmed that the ion-conductive channel size of the ion-conductive material having a relatively high molar ratio of the hydrophobic repeating unit is relatively small. That is, it was confirmed that in the ion-conductive material having a relatively high molar ratio of hydrophobic repeating units, the size of the hydrophilic channel formed by the phase separation of the hydrophilic repeating units was formed smaller, and as a result, it was seen that the crossover of vanadium in the redox flow battery could be more effectively prevented. This helps to increase the overall energy efficiency (E.E) by increasing the current efficiency (C.E) of the energy storage system.

[ Experimental example 3: performance analysis of the prepared ion exchange membranes

For the ion exchange membranes prepared in example 1-1, comparative example 1-1 and comparative example 1-2, the voltage efficiency, current efficiency and system efficiency were measured, and the results are shown in table 2 below.

the Energy Efficiency (EE) of the ion exchange membrane constituting the following device was measured, and the electrochemical characteristics were measured.

The device for measuring energy efficiency consists of a measuring device with 25cm²The two aqueous solution tanks and the pump to measure the electrochemical characteristics in the VRFB. As the cathode solution, 30mL of a solution containing 1.7M VOSO was used₄And 3M H₂SO₄And as the anode solution, an aqueous solution (an aqueous solution of trivalent vanadium) in which the cathode solution is electrolytically reduced is used. The amount of the cathode solution is slightly larger than that of the anode solution to suppress overcharge. The measuring cell is composed of a film to be measured, and has a size of 25cm²A heat-treated Carbon felt (a product from Nippon Carbon co., Ltd.) and a current collector (current collector). A constant potential/constant current meter was used for the charge/discharge of the unit cell for measurement and was set at 60mA/cm²The charge/discharge current density was measured. In addition, the charge/discharge of the unit cell is performed in an off manner (cut-off manner) five times by setting the charge voltage to 1.6V and the discharge voltage to 1.0V, and then the Current Efficiency (CE), the Voltage Efficiency (VE), and the Energy Efficiency (EE) are calculated by using the following formula 7.

[ formula 7]

CE＝Q_D/Q_C

VE＝E_AD/E_AC

EE＝CE×VE

Here, Q_C[C]And Q_D[C]Is the coulomb quantity during charging and discharging, E_AC[V]And E_AD[V]Is the battery voltage at the time of charging and discharging.

[ Table 2]

1) The thickness ratio of the second ion-conductive material prepared in preparation example 1-1 having a relatively high molar ratio of hydrophobic repeating units to the first ion-conductive material prepared in preparation example 1-2 having a relatively high molar ratio of hydrophilic repeating units was 7: 3. At this time, the thickness ratio is the sum of the thickness impregnated into the porous support and the thickness of the ion-conductive layer formed on the surface of the porous support.

Referring to table 2 above, it can be confirmed that, in the case of the ion exchange membrane manufactured in example 1-1, the current efficiency shows a performance that the ion conductive material having the hydrophilic repeating units at a relatively high molar ratio has relatively good ion conductivity, the voltage efficiency shows a performance that the ion conductive material having the hydrophobic repeating units at a relatively high molar ratio has relatively good durability, and the system efficiency is improved as a whole as compared to the ion exchange membranes manufactured in comparative example 1-1 and comparative example 1-2.

While the invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

[ description of reference numerals and symbols ]

1: ion exchange membrane

10. 10-1, 10-2: porous support

20. 20-1, 20-2: first ion conductive material

21. 21-1, 21-2: first ion conductive layer

30. 30-1, 30-2: a second ion conductive material

31. 31-1, 31-2: second ion conductive layer

102: battery case

102A: cathode battery

102B: anode cell

104: ion exchange membrane

106: cathode electrode

108: anode

110: cathode electrolyte storage tank

112: anode electrolyte storage tank

114. 116: pump and method of operating the same

118: power supply/load

201: ion exchange membrane

202: electrode for electrochemical cell

203: pump and method of operating the same

204：1M H₂SO₄

205: LCR (liquid Crystal resistor) measuring meter

[ Industrial Applicability ]

The present invention relates to an ion exchange membrane, a method of manufacturing the ion exchange membrane, and an energy storage system including the ion exchange membrane. According to the ion exchange membrane, both performance efficiency and voltage efficiency of the energy storage system are improved due to excellent ion conductivity properties and reduced membrane resistance, so that the overall efficiency of the energy storage system can be improved, and durability of the energy storage system can be ensured by having excellent morphological stability and reducing crossover of vanadium ions.