KR20190079168A - Membrane-electrode assembly prepared from cation exchange membnrane for producing hydrogen water and method for preparing membrane-electrode assembly - Google Patents

Abstract

The present invention relates to a method for preparing a membrane-electrode assembly for efficient hydrogen water production and to the membrane-electrode assembly. A method for preparing a membrane-electrode assembly comprises the following steps of: impregnating a porous polymer film with a mixed solution of a monomer, a cross-linking agent, and an initiator to fill pores; performing cross-linking polymerization of the mixed solution filled in the pores of the porous polymer film; impregnating a cross-linked polymerized polymer film with a solution having a cation exchange group and introducing the cation exchange group into the polymer film to prepare a pore-filled cation exchange membrane; impregnating the pore-filled cation exchange membrane with a solution containing platinum ions to exchange ions; and impregnating the pore-filled cation exchange membrane exchanged with platinum ion with an alkaline aqueous solution to reduce the platinum ions to form an electrode layer. In addition, the membrane-electrode assembly for hydrogen water production includes a porous polymer film having the thickness less than or equal to 25 μm and an electrode layer by an electrode metal on the surface of the porous polymer film, is filled with a cation exchange resin in pores of the porous polymer film, and has the electrode metal.

Description

TECHNICAL FIELD [0001] The present invention relates to a membrane-electrode assembly and a membrane-electrode assembly based on a pore-filled cation exchange membrane for efficient water generation. More particularly, the present invention relates to a membrane-electrode assembly and a membrane-

The present invention relates to a method for producing a membrane-electrode assembly for efficient water production and a membrane-electrode assembly.

The ion exchange membrane is a synthetic resin membrane that allows only one ion to pass through by selecting a cation and an anion, and has a cation exchange membrane and an anion exchange membrane.

The cation exchange membrane has a negative charge, so negative ions pass through only positive ions without repelling them. On the contrary, the anion exchange membrane has a positive charge and has a property of passing only negative ions. Typical ion exchange membranes include a cation exchange membrane having a sulfonic group (group) and an anion exchange membrane having a quaternary ammonium group.

These ion exchange membranes are widely used in the fields of fuel cells, diffusion dialysis, redox flow cells, water treatment, and desalination of seawater. Since they have high selectivity, they have low permeability of solvent and non-ionic solute, Low mechanical strength, and chemical resistance.

As a technique for an ion exchange membrane, Korean Patent Laid-Open Publication No. 2002-0074365 discloses a method for producing a solution containing a polymer having ion exchange ability, a crosslinking agent is added to the solution, and an ion exchange membrane is prepared through crosslinking , And heat treating the ion exchange membrane. However, the technique disclosed in the above patent document needs to use a reinforcing material together because of the mechanical property restriction of the ion exchange resin.

On the other hand, in general, a monomer paste is cast on a nonwoven fabric made of PVC and PE, and a base film is formed through thermal polymerization or photopolymerization, and quaternary amination or sulfonation treatment is carried out to form an anion exchange membrane Or a cation exchange membrane is produced. However, in this case, the thickness of the ion exchange membrane becomes thicker than 150 탆 in order to obtain a mechanical property of a certain level or higher, and the continuous manufacturing process becomes impossible and the manufacturing cost increases.

Therefore, studies have been made on a method for producing an ion exchange membrane capable of exhibiting sufficient mechanical properties for ion exchange, while reducing the thickness of the ion exchange membrane. In relation to this, in Korean Patent Publication No. 2012-0059585, Discloses a method for producing an ion exchange membrane having a thin thickness by using the ion exchange membrane as a base membrane.

On the other hand, studies on water quality have been actively conducted since the late 1990s, mainly in Japan, and commercialization began in earnest as the results of related research were handled in 1997 by the American Biology BBRC. Currently, in Japan, hydrogen is said to account for more than 10% of the total drinking water market.

Hydrophobic water has been known to enhance the immune system by removing active oxygen, and to prevent aging and adult diseases. For example, a study by Okayama University found that drinking water showed a significant antioxidant effect when drinking water was used to examine changes in periodontal tissue in rats [T. Tomofuji et al., Scientific Report, 4, Article number: 5534 (2014)].

Hydrogen production can be classified into hydrogen gas injection type, stick type, reagent addition type and electrolysis type.

Electrolytic electrolytic membrane electrolysis is a method of electrolyzing water using a membrane-electrode assembly (MEA) in which an electrode catalyst is bonded to both sides of a polymer electrolyte. It is possible to carry out electrolysis with high efficiency, produce hydrogen of high purity from pure water, and have a high electrolytic efficiency.

The most important part of the method for producing hydrogen water using MEA is the performance of MEA. Therefore, it is generally required to have high chemical stability and high hydrogen ion conductivity, and thus, MEA is usually manufactured using Nafion.

However, since Nafion is very expensive, there is a problem of greatly increasing the manufacturing cost of MEA. Therefore, it is required to develop a hydrogen ion exchange membrane and a high efficiency MEA based on the hydrogen ion exchange membrane, which are chemically stable and have high hydrogen ion conductivity and low manufacturing cost for efficient and economical production of water.

The present invention provides a method for producing a membrane-electrode assembly for efficient and economical production of hydrofluoric acid and an electrochemical water-producing apparatus using the same.

The present invention relates to a method for producing a membrane-electrode assembly, comprising the steps of: impregnating a porous polymer film with a mixed solution containing a monomer, a crosslinking agent and an initiator to fill the pores; A step of impregnating the crosslinked polymer film with a solution having a cation exchanger to prepare a pore-filled cation exchange membrane by introducing a cation exchanger into the polymer film; impregnating the pore-filled cation exchange membrane with the platinum ion- And a step of impregnating the platinum ion-exchanged pore-filled cation exchange membrane with an alkali aqueous solution to reduce platinum ions to form a catalyst layer.

The cation exchanger includes a sulfonic acid group (-SO ₃ H), a carboxyl group (-COOH), a phosphonic group (-PO ₃ H ₂ ), a phosphonic group (-HPO ₂ H), an acidic group (-AsO ₃ H ₂ ) And a selinolytic group (-SeO ₃ H).

The monomer may be selected from the group consisting of styrene, N-phenylacrylamide, N- (triphenylmethyl) methacrylamide, ethylene glycol phenyl ether acrylate, 2 2-Hydroxy-3-phenoxypropyl acrylate, 2-sulfoethyl methacrylate, and 3-sulfopropyl methacrylate. Lt; / RTI >

The crosslinking agent may be selected from the group consisting of divinylbenzene, ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,6-hexanediol diacrylate, Triethylene glycol diacrylate, tricyclodecane dimethanol diacrylate, trimethylolpropane triacrylate, glycerin triacrylate, trimethylol propane triacrylate, trimethylol propane triacrylate, trimethylol propane triacrylate, trimethylol propane triacrylate, Tris (2-hydroxyethyl) isocyanurate triacrylate, and tris (2-hydroxyethyl) isocyanurate triacrylate.

It is preferable that two or more crosslinking agents having different molecular weights are used.

The crosslinking agent is a mixture of divinylbenzene, ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, and 1,6-hexanediol dimethacrylate, and the crosslinking agent is a mixture of divinylbenzene 60 to 90 By weight of ethylene glycol dimethacrylate, 3 to 15% by weight of ethylene glycol dimethacrylate, 3 to 15% by weight of 1,3-butanediol dimethacrylate and 3 to 15% by weight of 1,6-hexanediol dimethacrylate .

The crosslinking polymerization may be carried out by photo-crosslinking or thermal crosslinking.

The initiator may use at least one photoinitiator selected from the group consisting of benzophenone, benzyldimethyl ketal, 1,2-diphenylethanedione, hydroxyldimethyl acetopone and? -Hydroxycyclohexylphenyl methanone.

The initiator may use at least one thermal initiator selected from the group consisting of benzoyl peroxide, benzoyl peroxide, azobisisobutyronitrile, azomethane and azoisopropane.

The crosslinking agent is preferably contained in an amount of 10 to 30% by weight based on 100% by weight of the total amount of the monomer and the crosslinking agent.

The initiator is preferably contained in an amount of 1 to 5 parts by weight based on 100 parts by weight of the monomer.

The step of ion-exchanging with the metal ions for forming an electrode layer includes the steps of: impregnating the pore-filled cation exchange membrane in an aqueous solution of sulfuric acid for 1 to 15 hours followed by washing with water; dissolving a precursor containing metal ions for forming an electrode layer in methanol or a mixed solvent of ethanol and water Containing solution to prepare a platinum ion-containing solution, and impregnating the washed pore-filled cation-exchange membrane with a metal ion-containing precursor solution for forming an electrode layer.

The aqueous sulfuric acid solution may have a concentration of 0.5 to 2M.

The mixed solvent of methanol or ethanol and water preferably has a volume ratio of methanol or ethanol to water of 1: 2 to 1: 5.

The metal ion-containing precursor solution for forming an electrode layer preferably has a concentration of metal ions for forming an electrode layer of 0.1 to 0.7 mM.

The step of ion-exchanging with the metal ions for forming the electrode layer is preferably performed for 20 minutes to 1 hour.

The reduction is performed by impregnating a pore-filled cation exchange membrane ion-exchanged with the metal ion for forming the electrode layer into an aqueous alkaline solution having a pH of 11 to 14 with at least one dissolved solution of a reducing solution selected from the group consisting of NaBH ₄ and LiAlH ₄ desirable.

The impregnation of the reducing solution is preferably performed for 30 minutes to 5 hours.

The reducing solution may be prepared by dissolving NaBH ₄ in an aqueous alkaline solution at a concentration of 0.6 to 0.9M.

The metal ion for forming the electrode layer may be an ion of platinum, ruthenium, or a mixed metal thereof.

The alkali aqueous solution preferably has a temperature of 25 to 60 캜.

The porous polymer film may have a thickness of 25 占 퐉 or less (excluding 0 占 퐉).

The porous polymer film may be formed from a group consisting of linear low density polyethylene (LLDPE), low density polyethylene (LDPE), polyethylene (PE) copolymer, polypropylene, EVA (Ethylene Vinyl Alcohol) You can use what is selected.

Washing the porous polymer film with a solvent for 30 minutes to 5 hours, and then drying the porous polymer film.

The solvent may be selected from the group consisting of acetone, dimethylacetamide (DMAc), dimethylformamide (DMF), acetonitrile, methanol and ethanol.

The method may further include a step of impregnating the membrane-electrode assembly obtained in the step of reducing the platinum ions with an aqueous sulfuric acid solution for 30 minutes to 5 hours, followed by washing with water.

The present invention provides a membrane-electrode assembly, wherein the membrane-electrode assembly has a cation exchange resin filled in pores of a porous polymer film having a thickness of 25 m or less, platinum exists in the cation exchange resin, And a catalyst layer formed of platinum on the surface of the polymer film.

The cation exchange resin may be one produced by polymerization of a monomer, a crosslinking agent and a photoinitiator or a thermal initiator.

The porous polymer film may be formed from a group consisting of linear low density polyethylene (LLDPE), low density polyethylene (LDPE), polyethylene (PE) copolymer, polypropylene (PP), ethylene vinyl alcohol (EVA) It can be selected.

The monomer may be selected from the group consisting of styrene, N-phenylacrylamide, N-triphenylmethyl methacrylamide, ethylene glycol phenyl ether acrylate, From a group consisting of 2-hydroxy-3-phenoxypropyl acrylate, 2-sulfoethyl methacrylate and 3-sulfopropyl methacrylate. And may be at least one selected.

The crosslinking agent may be selected from the group consisting of divinylbenzene, ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,6-hexanediol diacrylate, Triethylene glycol diacrylate, tricyclodecane dimethanol diacrylate, trimethylolpropane triacrylate, glycerin triacrylate, trimethylol propane triacrylate, trimethylol propane triacrylate, trimethylol propane triacrylate, trimethylol propane triacrylate, (2-hydroxyethyl) isocyanurate triacrylate having a molecular weight differing from that of the polyisocyanate compound.

The crosslinking agent may include divinylbenzene, ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, and 1,6-hexanediol dimethacrylate.

The photoinitiator may be at least one selected from the group consisting of benzophenone, benzyldimethylketal, 1,2-diphenylethanedione, hydroxyldimethylacetopone, and? -Hydroxycyclohexylphenylmethanone.

The thermal initiator may be at least one selected from the group consisting of benzoyl peroxide, benzoyl peroxide, azobisisobutyronitrile, azomethane and azoisopropane.

The membrane-electrode assembly of the present invention is fabricated on the basis of a pore-filled cation exchange membrane which is thin and has excellent electrical performance and strong physical strength, so that the manufacturing cost is very low compared with the conventional Nafion-based membrane- Can be obtained.

The membrane-electrode assembly of the present invention can be produced by filling a pore with a cation exchange resin using a porous polymer film having a thickness of 25 탆 or less as a base material, thereby achieving continuous production by a roll-to- It is possible to improve the productivity.

In addition, the porous polymer film used as the base material has excellent mechanical strength, so that the thickness can be made thinner, the electrical resistance can be remarkably lowered, and sufficient mechanical properties can be ensured.

Furthermore, by using two or more crosslinking agents having different molecular weights, the crosslinking density can be increased and the chemical and physical stability can be greatly improved.

In addition, the durability of the hydrocarbon-based cation exchange membrane can be improved by spray coating a Nafion solution on the surface.

Fig. 1 is a graph showing the results of measurement of changes in the concentration of water in a constant current condition. Fig.
FIG. 2 is a graph showing voltage changes during the production of hydrogen peroxide under constant current conditions. FIG.

The present invention provides a method for producing a membrane-electrode assembly using a pore-filled cation exchange membrane and a membrane-electrode assembly manufactured thereby.

The membrane-electrode assembly provided by the present invention can be prepared by preparing a pore-filled cation exchange membrane and introducing a catalyst into the surface and pores thereof. Hereinafter, the present invention will be described in more detail.

First, a method for producing the pore-filled cation exchange membrane of the present invention will be described.

The pore-filled cation exchange membrane of the present invention uses a porous polymer film as a substrate. By using a porous polymer film as a substrate, it is possible to produce a pore-filled cation-exchange membrane by a roll-to-roll process, thereby improving productivity.

The porous polymer film is not particularly limited and may be suitably used in the present invention as long as it is used in the production of an ion exchange membrane.

Examples of the porous polymer film include linear low density polyethylene (LLDPE), low density polyethylene (LDPE), polyethylene (PE) copolymer, polypropylene (PP), ethylene vinyl alcohol (EVA) ).

The porous polymer film is not necessarily limited to this, but one having a thickness of 25 탆 or less can be used. Even if a thin film is used in this way, the porous polymer film used as the base material can provide sufficient mechanical properties and can function effectively as the membrane-electrode assembly of the present invention. In addition, since the thickness is thin, the amount of material used for manufacturing the membrane-electrode assembly can be reduced, which is preferable for reducing manufacturing cost.

If the thickness of the porous polymer film is more than 25 mu m, the electrical resistance of the membrane may increase.

The thickness of the porous polymer film is not particularly limited as long as it is a thin film having a thickness of 25 탆 or less, but preferably 5 탆 or more, for example, 7 탆 or more, 8 탆 or more and 10 탆 or more.

The porous polymer film may be used after being washed with a solvent. The washing may be carried out for 30 minutes to 5 hours. The cleaning is for removing impurities on the surface of the porous polymer film, and it is preferable to remove impurities that affect pore penetration of the monomer. Examples of the solvent that can be used for the washing include, but are not limited to, polar solvents such as acetone, dimethylacetamide (DMAc), dimethylformamide (DMF), acetonitrile, methanol methanol, ethanol, and the like. Of these, acetone is most suitable when considering volatility and polarity.

The washing time is not particularly limited as long as it is 30 minutes or longer, but it is preferably carried out within 5 hours in terms of process economy. More preferably from 30 minutes to 3 hours. After the washing, the porous polymer film is dried.

In the present invention, the pores of the porous polymer film are filled with a cation exchange resin. Exchange resin, the porous polymer film is loaded on the raw material solution for polymerization of the cation exchange resin to fill the raw material solution into the pores.

The raw material solution may be a mixed solution containing a monomer, a crosslinking agent and an initiator. The mixed solution may be impregnated with the porous polymer film to fill the pore raw material solution, and the cation exchange resin may be filled in the pores by crosslinking polymerization.

The monomer is a main material which forms a cation-exchange resin by polymerization. The monomer is selected from the group consisting of styrene, N-phenylacrylamide, N- (triphenylmethyl) methacrylamide, 2-hydroxy-3-phenoxypropyl acrylate, 2-sulfoethyl methacrylate and 3- (2-hydroxyethyl) methacrylate. And 3-sulfopropyl methacrylate. These may be used singly or in combination of two or more.

The crosslinking agent may be selected from the group consisting of divinylbenzene, ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,6-hexanediol diacrylate, Triethylene glycol diacrylate, tricyclodecane dimethanol diacrylate, trimethylolpropane triacrylate, glycerin triacrylate, trimethylol propane triacrylate, trimethylol propane triacrylate, trimethylol propane triacrylate, trimethylol propane triacrylate, Tris (2-hydroxyethyl) isocyanurate triacrylate, and the like can be used.

At this time, it is preferable that the cross-linking agent is used by mixing two or more cross-linking agents to improve the chemical and physical durability of the membrane-electrode assembly. More preferably, the use of a cross-linking agent having a different molecular weight from the two or more cross-linking agents provides an effect that the distance between the polymer chains and the free volume are appropriately controlled to reduce the ion transport resistance.

Examples of the crosslinking agent include divinylbenzene (weight average molecular weight 130.19), ethylene glycol dimethacrylate (weight average molecular weight 198.22), 1,3-butanediol dimethacrylate (weight average molecular weight 226.27), 1,6- And hexanediol dimethacrylate (weight average molecular weight: 254.32) are mixed, the cross-linking structure is as follows.

By using two or more crosslinking agents having different molecular weights as described above, the crosslinking density of the polymer can be formed more densely. That is, by effectively cross-linking a polymer chain with a long distance between the polymer chain and the polymer chain, the crosslink density can be increased and the interval between the polymer chain can be widened, thereby improving the ionic conductivity.

For example, when the four types of crosslinking agents as described above are used, it is not limited thereto, but it is preferable that 60 to 90% by weight of divinylbenzene, 3 to 15% by weight of ethylene glycol dimethacrylate, 3 to 15% by weight of 1,3-butanediol dimethacrylate, and 3 to 15% by weight of 1,6-hexanediol dimethacrylate.

The crosslinking agent may be contained in an amount of 10 to 30% by weight based on 100% of the total weight of the monomer and the crosslinking agent. If it is contained in an amount less than 10% by weight, the physical and chemical durability tends to deteriorate. If it exceeds 30% by weight, the ion conductivity tends to decrease.

The crosslinking polymerization of the monomer and the crosslinking agent can be carried out by photoinitiation or thermal decomposition. For this purpose, a reaction initiator is included. As the reaction initiator, a photoinitiator or a thermal initiator may be used.

Examples of the photoinitiator include benzophenone, benzyldimethyl ketal, 1,2-diphenylethanedione, hydroxyldimethyl acetopone, and? -Hydroxycyclohexylphenyl methanone, which may be used alone or as a mixture of two or more It can also be used.

On the other hand, the above-mentioned initiator may include benzoyl peroxide, benzoyl peroxide, azobisisobutyronitrile, azomethane, and azoisopropane. These may be used alone or in admixture of two or more.

The reaction initiator may be used in an amount of 1 to 5% by weight based on 100 parts by weight of the monomer. When the amount is less than 1% by weight, polymerization reaction does not sufficiently take place. When the amount is more than 5% by weight, there is a problem such as lowering of initiation efficiency and remaining unreacted initiator.

As described above, the porous polymer film may be impregnated with the mixed solution, filled therein, and subjected to cross-linking polymerization to prepare a pore-filled cation exchange membrane. Specifically, although not limited thereto, the porous polymer film is filled with a monomer, and the porous polymer film is sandwiched between two release films, and the polymer film is closely contacted by rolling. After the excess monomers are removed, And then light-cured or heat-cured.

The photopolymerization and the thermopolymerization are not particularly limited. However, in the case of photopolymerization, the photopolymerization can be performed at a room temperature for 1 to 10 minutes based on a UV light source of 1 kW. The thermal polymerization is carried out at a temperature range of 60 to 90 ° C for 1 to 5 hours can do.

In the polymerization, it is preferable to seal the edges of the release film and the glass plate, which are located on both surfaces of the porous polymer film, with capton tape or the like in order to prevent contact with oxygen and loss of the monomer.

Thereby obtaining a porous polymer film filled with the polymer in the pores, and introducing a cation exchanger into the polymer filled in the pores of the porous polymer film.

The cation exchanger is introduced for the production of hydrogen peroxide. The cation exchanger is not particularly limited, and examples thereof include a sulfonic acid group (-SO ₃ H), a carboxyl group (-COOH), a phosphonic group (-PO ₃ H _2), Phosphinicosuccinic nikgi (-HPO ₂ H), oh sonic group (-AsO ₃ H ₂₎ and cells Reno nikgi (-SeO ₃ H) or the like. These cation exchangers may be any one or two or more.

The cation exchange group can be introduced into the polymer by dissolving the compound having the cation exchange group in an organic solvent and impregnating a porous polymer film filled with the polymer in the pores. The introduction reaction of the cation exchanger is not particularly limited, but can be carried out, for example, by impregnation at a temperature of 30 to 60 DEG C for 3 to 15 hours.

Whereby a pore-filled cation exchange membrane into which the cation exchange resin is introduced into the pores can be obtained. The Nafion solution may be sprayed onto the surface of the pore-filled cation exchange membrane, if necessary. As a result, the durability of the hydrocarbon-based cation exchange membrane can be further improved.

And introducing a metal into the pore-filled cation exchange membrane to form an electrode layer on the surface. The electrode layer may be formed by slurry coating or electrolytic plating. In the present invention, however, it is preferable to form an electrode layer by electroless plating, especially non-planar-impregnation / reduction. When the electrode layer is formed by the non-equilibrium-impregnation / reduction method, metals are introduced into the pores of the porous polymer film as well as the surface of the cation exchange membrane, thereby improving the electrochemical characteristics. .

In order to accomplish this, a step of impregnating a pore-filled cation exchange membrane with an aqueous solution of sulfuric acid, washing with distilled water, and drying. The step of immersing in the sulfuric acid aqueous solution is not particularly limited, but it is preferable that the pore-filled cation exchange membrane is contained in an aqueous sulfuric acid solution of 0.5M or more, more preferably 1M or more, and 2M or less, By impregnation for 6 hours or more, preferably 15 hours or less, 12 hours or less, more preferably 10 hours or less.

Thereafter, the metal ion may be introduced by impregnating the precursor solution containing the metal component for forming an electrode layer with the pore-filled cation exchange membrane. The metal ions may be introduced into the electrode layer by impregnating the precursor solution containing the metal component with the pore-filled cation exchange membrane. The metal ions are introduced into the surface and pores of the cation exchange membrane, and the metal ions are introduced into the cation exchange membrane of the cation exchange membrane.

The metal precursor for forming an electrode layer is prepared by dissolving a metal precursor for forming an electrode layer in a mixed solvent of methanol and water, preferably methanol or ethanol, and water in a ratio of 1: 2 to 1: 5, more preferably 1: 2 to 1: . The metal precursor for electrode layer formation is preferably dissolved at a concentration of 0.1 to 0.7 mM, more preferably 0.1 to 0.5 mM, and still more preferably 0.2 to 0.5 mM.

The metal for forming the electrode layer is not limited to this, and may be suitably used as long as it can function as an electrode. For example, platinum, ruthenium, a mixed metal of platinum and ruthenium, and the like, and it is more preferable to use platinum.

It is preferable to impregnate the pore-filled cation exchange membrane with the metal precursor solution for forming the electrode layer for 20 minutes to 1 hour, more preferably 30 minutes to 1 hour. By such impregnation, the metal for forming the electrode layer is diffused and ion-exchanged into the pore-filled ion exchange membrane.

When the metal concentration and the impregnation time of the solution impregnated with the pore-filled ion exchange membrane are less than the above range, water decomposition does not sufficiently take place and the efficiency of producing hydrogen water lowers, and in an excessive amount, the resistance increases, which is not preferable.

The catalyst layer can be formed by reducing metal ions introduced into the cation exchange membrane. The reduction can be performed by impregnating the cation exchange membrane into which the metal ion is introduced with the reducing agent solution. Specifically, the metal ions substituted on the surface of the cation-exchange membrane first come into contact with the reducing agent and are reduced by the chemical reduction, and then the metal ions permeate into the pores of the cation-exchange membrane to form metal crystal nucleation sites in the pores, Is reduced by reduction.

For the reduction, an alkali aqueous solution of pH 11-14, more preferably pH 12-14, having a temperature range of room temperature (25 ° C) to 60 ° C, more preferably 30 ° C to 50 ° C, is added to NaBH ₄ And LiAlH ₄ to prepare a reducing solution, and impregnating the reducing solution with a pore-filled ion exchange membrane into which the metal ion is introduced.

The time for impregnation with the reducing solution is not limited thereto, but can be, for example, 30 minutes to 10 hours, 30 minutes to 7 hours, 30 minutes to 5 hours, 45 minutes to 3 hours. When the impregnation is carried out for less than 30 minutes, the reduction of the introduced metal ions is not sufficient, and if it exceeds 10 hours, no further reduction effect can be obtained.

Thereafter, the membrane-electrode assembly is further subjected to an aqueous sulfuric acid solution for 30 minutes or more, preferably 1 hour or more, and 5 hours or less, more preferably 3 For a period of time or less, followed by washing with distilled water.

For example, when the metal for forming the electrode layer is Pt and the reducing agent is NaBH ₄ , when the cation exchange membrane into which the Pt cation is introduced is impregnated with the reducing agent solution, the Pt ions substituted on the surface of the cation exchange membrane are chemically reduced Is reduced by the reaction.

BH ₄ ^- + 8OH ^- + 4Pt (II) -> H ₂ BO ₃ ^- + 5H ₂ O + 4Pt (0)

Subsequently, the Pt ions substituted in the pores of the cation exchange membrane are reduced by the following reaction.

BH ₄ ^- + 8OH ^{- -} > H ₂ BO ₃ ^- + 5H ₂ O + 8e ^-

8e ^- + 4Pt (II) ^- > 4Pt (0)

By such a non-planar-impregnation / reduction method, it is possible to introduce an electrode into the surface of the cation exchange membrane, thereby manufacturing a membrane-electrode assembly. The membrane electrode assembly obtained by the present invention can be suitably used for producing hydrogen water.

The membrane-electrode assemblies provided by the present invention are thin, have a strong physical strength, and are thin in thickness to provide excellent electrical performance. In addition, compared to conventional Nafion-based membrane-electrode assemblies, it is possible to significantly reduce manufacturing costs and provide equivalent performance.

Example

Hereinafter, the present invention will be described in more detail with reference to examples. The presently preferred embodiments of the present invention are not limited to the following specific embodiments.

Examples 1 to 5

1. Preparation of Cation Exchange Membrane

As a porous polymer film, a polyethylene porous film (thickness: 25 mu m, W-Scope Korea Co. Ltd.) was washed in an acetone solvent for 3 hours and dried in an oven.

80 parts by weight of styrene (Sty) as a monomer for polymerization and 20 parts by weight of a crosslinking agent were mixed and used. Examples of the crosslinking agent include divinylbenzene (DVB), ethylene glycol dimethacrylate (EGDMA), 1,3-butanediol dimethacrylate (BDDMA) and 1,6-hexanediol dimethacrylate (HDDMA) Were used in different weight ratios as shown in Table 1.

As the polymerization initiator, benzoyl peroxide (BPO) thermal polymerization initiator was used in an amount of 2 parts by weight based on the monomer weight.

The monomer, crosslinking agent and photoinitiator were mixed to prepare a monomer solution.

The washed porous film was impregnated with the monomer solution to fill the pores of the porous film with the monomer.

The porous film filled with the monomers in the pores was sandwiched between two release films, adhered to each other through rolling, and excess monomers were removed.

Then, the porous film filled with the monomers in the pores was inserted between two glass plates, sealed with capton tape to prevent contact with oxygen and loss of monomer, and thermal polymerization was carried out at 80 ° C for 3 hours.

After the thermal polymerization, the porous film was impregnated with a solution of chlorofulfonic acid (20 parts by weight) dissolved in dichlorobenzene at 35 DEG C, and the sulfonation reaction was carried out for 12 hours.

Finally, the microporous membrane was sequentially washed with dichlorobenzene and distilled water to prepare pore-filled cation exchange membranes (ion exchange membranes 1 to 5), which were then impregnated with 0.5 M NaCl solution and stored.

The prepared cation exchange membranes 1 to 5 were impregnated in a 1M sulfuric acid aqueous solution for 6 hours, washed with distilled water and dried.

Thereafter, Pt (II) (NH ₃ ) ₄ Cl ₂ (tetra-amine platinum chloride hydrate, 98%) was added to a mixed solvent of methanol and water at a volume ratio of 1: 3 at a concentration of 0.3 mM To prepare a solution. Then, the cleaned cation exchange membrane was impregnated in the solution for 40 minutes so that platinum ions were diffused and ion-exchanged into the cation exchange membrane.

NaBH ₄ was dissolved at a concentration of 0.8M in an aqueous alkali solution of pH 13 preheated to 50 ° C to prepare a reducing solution.

The cation exchange membrane substituted with platinum ion in the reducing solution was impregnated and then reduced to platinum by a reduction reaction for 2 hours to form an electrode layer, thereby preparing a membrane-electrode assembly.

The membrane-electrode assembly thus prepared was impregnated in a 0.5M sulfuric acid aqueous solution for 2 hours and then washed with distilled water (membrane-electrode assemblies 1 to 5).

Example 6

The pore filling cation exchange membrane of Example 5 was brought into close contact with a hot plate heated to 80 DEG C, and then a 5 wt% solution of Nafion (in IPA, D521, DuPont) was sprayed using a spray gun at a loading amount of 1 mg / Pore filling The Nafion was coated on the surface of the cation exchange membrane to prepare a pore-filled cation exchange membrane (ion exchange membrane 6).

The Nafion coated pore-filled cation exchange membrane was dried in a drying oven at 80 캜 for 1 hour.

Thereafter, one side was dried and the other side was subjected to Nafion coating under the same conditions.

Subsequently, membrane-electrode assemblies were prepared for the cation exchange membrane in the same manner as in Example 1 (membrane-electrode assembly 6).

Comparative Example 1

A membrane-electrode assembly (membrane-electrode assembly 7) was prepared by forming an electrode layer of platinum on Nafion 117 of DuPont, a commercial cation-exchange membrane, in the same manner as in Example 1.

Experimental Example

1. Evaluation Method

(1) Evaluation of membrane characteristics

The ion-exchange capacity ( IEC ) of the cation exchange membrane was measured by a conventional acid-base titration and was calculated by the following equation (1).

(1)

(One)

In the above equation, W _{dry memb} is the mass of the dried membrane, C is the concentration of the titrant solution, and V is the volume of the solution used for titration.

The water uptake ( WU ) was measured by measuring the wet weight ( W _wet ) and the dry weight ( W _dry ) of the membrane as shown in equation (2).

(2)

(2)

Membrane electrical resistance ( MER ) and ion conductivity (σ) were measured by AC impedance measurement as follows.

The membrane was sufficiently impregnated with a 0.5 M NaCl or 0.5 M HCl electrolyte solution, and then a 2-point probe clip cell and a potentiostat / impedance analyzer, including an impedance analyzer, The electrical resistance was measured by connecting a galvanostat, and MER and ion conductivity were calculated from the following equations (3) and (4), respectively.

(3)

(3)

(4)

(4)

In the above equation (3), R ₁ represents the sum of the resistance of the electrolyte and the membrane, R ₂ represents the resistance of the electrolyte solution, Area represents the effective area of the membrane and electrode, and L represents the thickness of the membrane.

In addition, the ion number ( E _m ) of ionized water is expressed by emf (2) using a 2-compartment diffusion cell And calculated by the following equations (5) and (6).

(5)

(5)

(6)

(6)

Where E _m is the measured cell potential, R is the gas constant, T is the absolute temperature, and F is the Faraday constant. In addition, C _L and C _H were tested as 1 mM and 5 mM, respectively, as concentrations of NaCl solution. The cell potential ( E _m ) was measured by connecting a pair of Ag / AgCl electrodes to a digital voltmeter.

The tensile strength of the prepared cation exchange membrane was measured according to ASTM method D-882-79 in a dry and wet condition using a universal testing machine (5567 model, Instron).

The chemical durability of ion exchange membranes was evaluated by the following Fenton oxidation experiments.

3% by weight H ₂ O ₂ and 2 ppm FeSO ₄ was prepared, and the temperature was maintained at 80 ° C. After the initial weight of the cation exchange membrane was measured, the Fenton reagent was impregnated with a cation exchange membrane. The weight of the cation exchange membrane was measured with time, and the weight reduction rate before and after the Fenton oxidation reaction was determined.

(2) Evaluation of water electrolysis characteristics (Hydrogen production)

In the evaluation of the electrolytic solution characteristics, the concentration of hydrogen produced at the anode under normal temperature and constant current conditions was measured using a dissolved hydrogen measuring device attached to the cell. Titanium electrodes were used for both the cathode and the anode, and the current density was fixed at 0.02 A / cm 2. Table 2 shows the evaluation conditions of the electrolytic solution characteristics.

2. Evaluation of membrane characteristics

The electrochemical characteristics of the membrane-electrode assemblies 1 to 6 prepared in Examples 1 to 6 and the membrane-electrode assembly 7 prepared in Comparative Example 1 were measured as described above, and the results are shown in Table 3.

As can be seen from the above Table 3, the membrane-electrode assembly 1 obtained in Example 1 has a lower ion conductivity than the membrane-electrode assembly 7 using Nafion in Comparative Example 1. [ However, it was found that the membrane-electrode assemblies 1 to 6 of Examples 1 to 6 had a small thickness and a large ion exchange capacity, indicating very low electrical resistance.

In addition, the membrane-electrode assemblies 1 to 6 of Examples 1 to 6 were not high in water content despite the high ion-exchange capacity, because the polyolefin porous polymer film as a support was an ionomer packed physically in the pores It is thought that it prevents excessive swelling and is also high in the degree of crosslinking.

On the other hand, in the membrane-electrode assemblies 2 to 6 of Examples 2 to 6, when a crosslinking agent having a relatively large molecular weight was used in combination with the membrane-electrode assembly 1 of Example 1 in which a single crosslinking agent (DVB) was used, The resistance was decreased, and at the same time, the ion number (transport number) of the membrane was maintained.

On the other hand, as the content of the cross-linking agent is increased, it can be seen that the increase of the water content is small, because the free volume of the film is increased as the content of the cross-linking agent having a larger molecular weight is increased. The electrical resistance of the membrane tends to decrease, and at the same time, the selective permeability of the ion exchange membrane is maintained due to the optimization of the crosslinking structure.

On the other hand, in the case of the membrane-electrode assembly 6 of Example 6 in which the Nafion spray coating was applied, the thickness was increased due to the introduction of the Nafion coating layer. As a result, compared with the membrane-electrode assembly 5 of Example 5, The electrical resistance in the HCl solution was the same level as that of the membrane-electrode assembly 5 of Example 5, although the resistance tended to increase somewhat. It can be interpreted that the characteristic of Nafion with high conductivity to hydrogen ion is expressed through surface coating.

The mechanical strength characteristics of the membrane-electrode assemblies 1 to 6 prepared in Examples 1 to 6 and the membrane-electrode assembly 7 prepared in Comparative Example 1 were measured, and the results are shown in Table 4.

As can be seen from the above Table 4, the membrane-electrode assemblies 1 to 5 of Examples 1 to 5 exhibited the membrane-electrode assembly 7 of Comparative Example 1 due to the strong physical properties and high degree of crosslinking of the support, And showed an excellent tensile strength of 4 times or more.

It can also be seen that the film-electrode assemblies 2 to 5 of Examples 2 to 5 using mixed crosslinking agents exhibited higher tensile strength values as compared with the membrane-electrode assembly 1 of Example 1 using DVB single crosslinking agent. This means that the crosslinking degree is improved by using a mixed crosslinking agent. However, it can be seen that the tensile strength tends to decrease slightly as the content of the crosslinking agent increases.

The membrane-electrode assemblies 5 and 6 prepared in Examples 5 and 6 and the membrane-electrode assembly 7 prepared in Comparative Example 1 were evaluated for their chemical stability through the Fenton oxidation experiment as described above. The results are shown in Table 5 Respectively.

As can be seen from the above Table 5, the membrane-electrode assembly 5 of Example 5 showed a weight reduction ratio of 2 times or more as compared with the membrane-electrode assembly 7 produced by Comparative Example 1 as a hydrocarbon base material. However, this weight reduction rate is significantly lower than that of commercially available CMX products of Astom, as shown in Table 5 above, which shows a weight reduction rate of 10% or more.

In addition, it can be seen that the membrane-electrode assembly 6 of Example 6 having the surface coated with Nafion has increased oxidation stability and has a weight reduction ratio value close to that of the membrane-electrode assembly 7 of Comparative Example 1. [ That is, even in the case of the membrane-electrode assembly of Example 5 in which the Nafion coating was not performed, it is possible to provide sufficient chemical stability due to high crosslinking density in actual applications, but additionally Nafion coating on the surface can provide a membrane-electrode assembly Lt; RTI ID = 0.0 > 7, < / RTI >

3. Evaluation of water electrolysis characteristics

The membrane-electrode assemblies 1 to 6 prepared in Examples 1 to 6 and the membrane-electrode assembly prepared in Comparative Example 1 were evaluated for hydrogen peroxide production performance as described above, and the results are shown in Figs. 3 and 4 Respectively.

As can be seen from FIG. 3, the amount of hydrogen produced by each of the membrane-electrode assemblies was not significantly different. This is consistent with the theoretical assumption that hydrogen production will not be different because it is a constant current condition. If the amount of hydrogen produced is small, it can be judged to be due to the defect of the ion exchange membrane or the effect of low ion selectivity.

It can also be seen from Fig. 4 that a constant value is maintained without changing the voltage. This means that a stable water decomposition reaction is taking place. If the hydrogen gas produced in the membrane-electrode assembly can not escape smoothly or if the catalyst in the electrode layer does not function, a sudden voltage increase may be observed. However, it can be confirmed that the voltage is stably maintained in all the membrane-electrode assemblies of Examples 1 to 6.

On the other hand, the water decomposition voltage tends to decrease as the content of the crosslinking agent increases. This is consistent with the electrical resistance of the ion exchange membrane described above. In particular, the membrane-electrode assembly 5 of Example 5 and the membrane-electrode assembly of Example 6 exhibited the same decomposition voltage as that of the Nafion-based membrane-electrode assembly of Comparative Example 1.

Claims (35)

Impregnating the porous polymer film with a mixed solution containing a monomer, a crosslinking agent and an initiator to fill the pores;
Crosslinking the mixed solution filled in the pores of the porous polymer film;
Impregnating the crosslinked polymer film with a solution having a cation exchanger and introducing a cation exchanger into the polymer film to prepare a pore filling cation exchange membrane;
Impregnating the pore-filled cation exchange membrane with a metal ion-containing solution for forming an electrode layer to ion-exchange a metal for forming an electrode layer; And
A step of impregnating a pore-filled cation exchange membrane exchanged with the metal ion for forming the electrode layer into an alkali aqueous solution to reduce metal ions for forming an electrode layer to form an electrode layer
Electrode assembly. The method of claim 1, wherein the cation exchanger is selected from the group consisting of a sulfonic acid group (-SO ₃ H), a carboxyl group (-COOH), a phosphonic group (-PO ₃ H ₂ ), a phosphonic group (-HPO ₂ H) -AsO ₃ H ₂ ) and a selinolytic group (-SeO ₃ H). The method of claim 1, wherein the monomer is selected from the group consisting of styrene, N-phenylacrylamide, N- (triphenylmethyl) methacrylamide, ethylene glycol phenyl ether acrylate, phenyl ether acrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-sulfoethyl methacrylate and 3-sulfopropyl methacrylate 3-sulfopropyl methacrylate). ≪ / RTI > The method of claim 1, wherein the crosslinking agent is selected from the group consisting of divinylbenzene, ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,6-hexanediol diacrylate , Hydroxypivalic acid neopentyl glycol diacrylate, tripropylene glycol diacrylate, dipropylene glycol diacrylate, triethylene glycol diacrylate, tricyclodecane dimethanol diacrylate, trimethylolpropane triacrylate, (2-hydroxyethyl) isocyanurate triacrylate, glycerin triacrylate, trimethylolpropane triacrylate, and tris (2-hydroxyethyl) isocyanurate triacrylate. 5. The method for manufacturing a membrane-electrode assembly according to claim 4, wherein the cross-linking agent has two or more different molecular weights. The crosslinking agent according to claim 1, wherein the crosslinking agent is a mixture of divinylbenzene, ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, and 1,6-hexanediol dimethacrylate, 60 to 90% by weight of divinylbenzene, 3 to 15% by weight of ethylene glycol dimethacrylate, 3 to 15% by weight of 1,3-butanediol dimethacrylate and 3 to 15% by weight of 1,6-hexanediol dimethacrylate % ≪ / RTI > The method of claim 1, wherein the cross-linking polymerization reaction is carried out by photo-crosslinking or thermal crosslinking. The method of claim 1, wherein the initiator is at least one photoinitiator selected from the group consisting of benzophenone, benzyldimethyl ketal, 1,2-diphenylethanedione, hydroxyldimethyl acetopone, and? -Hydroxycyclohexylphenyl methanone Lt; RTI ID = 0.0 > membrane-electrode < / RTI > The method of claim 1, wherein the initiator is at least one thermal initiator selected from the group consisting of benzoyl peroxide, benzoyl peroxide, azobisisobutyronitrile, azomethane and azoisopropane. The method for producing a membrane-electrode assembly according to claim 1, wherein the cross-linking agent is contained in an amount of 10 to 30% by weight based on 100% by weight of the total of the monomer and the cross-linking agent. The method for producing a membrane-electrode assembly according to claim 1, wherein the initiator is contained in an amount of 1 to 5 parts by weight based on 100 parts by weight of the monomer. The method according to claim 1, wherein the step of ion-
Immersing the pore-filled cation exchange membrane in an aqueous solution of sulfuric acid for 1 to 15 hours, followed by washing with water;
Dissolving a metal ion-containing precursor for forming an electrode layer in methanol or a mixed solvent of ethanol and water to prepare a platinum ion-containing solution; And
Impregnating the cleaned pore-filled cation exchange membrane with a metal ion-containing precursor solution for forming an electrode layer
≪ / RTI > wherein the process is performed by a process comprising: 13. The method of claim 12, wherein the aqueous sulfuric acid solution has a concentration of 0.5 to 2M. 13. The method for manufacturing a membrane-electrode assembly according to claim 12, wherein the mixed solvent of methanol or ethanol and water has a volume ratio of methanol or ethanol to water of 1: 2 to 1: 5. The method for producing a membrane-electrode assembly according to claim 1, wherein the metal ion-containing precursor solution for forming an electrode layer has a concentration of metal ion for forming an electrode layer of 0.1 to 0.7 mM. The method for producing a membrane-electrode assembly according to claim 1, wherein the step of ion-exchanging with metal ions for forming an electrode layer is performed for 20 minutes to 1 hour. 2. The method according to claim 1, wherein the reduction is performed by adding a pore-filled cation exchange membrane ion-exchanged with the metal ion for forming the electrode layer to an aqueous alkaline solution having a pH of 11 to 14 in the presence of at least one dissolved redox solution selected from the group consisting of NaBH ₄ and LiAlH ₄ Wherein the membrane-electrode assembly is impregnated with the electrolyte solution. The method for producing a membrane-electrode assembly according to claim 1, wherein the impregnation in the reducing solution is performed for 30 minutes to 5 hours. The method for producing a membrane-electrode assembly according to claim 18, wherein the reducing solution is NaBH ₄ or LiAlH ₄ dissolved in an aqueous alkaline solution at a concentration of 0.6 to 0.9M. The method for manufacturing a membrane-electrode assembly according to claim 1, wherein the metal ion for forming the electrode layer is an ion of platinum, ruthenium, or a mixed metal thereof. The method of claim 17, wherein the aqueous alkaline solution has a temperature of 20 to 60 占 폚. The method for producing a membrane-electrode assembly according to claim 1, wherein the porous polymer film has a thickness of 25 占 퐉 or less (excluding 0 占 퐉). The porous polymer film according to claim 1, wherein the porous polymer film is selected from the group consisting of LLDPE (Low Density Polyethylene), LDPE (Low Density Polyethylene), PE (Polyethylene) copolymer, PP, EVA (Ethylene Vinyl Alcohol) Rubber). ≪ / RTI > The method of claim 1, further comprising washing the porous polymer film in an acetone solvent for 30 minutes to 5 hours and then drying the porous polymer film. The method of claim 1, further comprising the step of impregnating the membrane-electrode assembly obtained in the step of reducing the platinum ions with an aqueous sulfuric acid solution for 30 minutes to 5 hours, followed by washing with water. 26. The method of any one of claims 1 to 25, further comprising spraying a Nafion solution onto the surface of the pore-filled cation exchange membrane to coat the membrane. A porous polymer film having a thickness of 25 mu m or less; And
On the surface of the porous polymer film, an electrode layer
Wherein the pores of the porous polymer film are filled with a cation exchange resin and the electrode metal is present. 28. The membrane-electrode assembly of claim 27, wherein said cation exchange resin is by polymerization of a monomer, a crosslinking agent and a photoinitiator or a thermal initiator. 28. The method of claim 27, wherein the porous polymeric film is selected from the group consisting of LLDPE (Low Density Polyethylene), LDPE (Low Density Polyethylene), PE (Polyethylene) copolymer, PP, EVA (Ethylene Vinyl Alcohol) Rubber). ≪ / RTI > 28. The method of claim 27, wherein the monomer is selected from the group consisting of styrene, N-phenylacrylamide, N- (triphenylmethyl) methacrylamide, ethylene glycol phenyl ether acrylate 2-hydroxy-3-phenoxypropyl acrylate, 2-sulfoethyl methacrylate, and 3-sulfopropyl methacrylate. methacrylate). < / RTI > 28. The method of claim 27, wherein the crosslinking agent is selected from the group consisting of divinylbenzene, ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,6-hexanediol diacrylate , Hydroxypivalic acid neopentyl glycol diacrylate, tripropylene glycol diacrylate, dipropylene glycol diacrylate, triethylene glycol diacrylate, tricyclodecane dimethanol diacrylate, trimethylolpropane triacrylate, Wherein the membrane-electrode assembly comprises two or more different molecular weights selected from the group consisting of glycerin triacrylate, trimethylolpropane triacrylate, and tris (2-hydroxyethyl) isocyanurate triacrylate. 28. The membrane-electrode assembly of claim 27, wherein the cross-linking agent comprises divinylbenzene, ethylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, and 1,6-hexanediol dimethacrylate. 28. The method of claim 27, wherein the photoinitiator is at least one selected from the group consisting of benzophenone, benzyldimethyl ketal, 1,2-diphenylethanedione, hydroxyldimethylacetopone, and alpha -hydroxycyclohexylphenylmethanone - Electrode junction. 28. The membrane-electrode assembly according to claim 27, wherein the thermal initiator is at least one selected from the group consisting of benzoyl peroxide, benzoyl peroxide, azobisisobutyronitrile, azomethane and azoisopropane. 28. The membrane-electrode assembly of claim 27, wherein the electrode metal is platinum, ruthenium, or a mixed metal thereof.

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