KR20220040233A - Electrode slurry for forming electrode coating layer and method for manufacturing membrane electrode assembly for fuel cell using the same - Google Patents

Abstract

The present invention relates to electrode slurry for forming an electrode coating layer for minimizing defects while increasing process efficiency in a process of manufacturing a membrane-electrode assembly for a fuel cell through a direct coating process, and a method for manufacturing a membrane-electrode assembly for a fuel cell using the same. The method for manufacturing a membrane-electrode assembly for a fuel cell according to the present invention includes the steps of: manufacturing electrode slurry including an active material and an additive having a boiling point of 200 deg. C or higher; forming an electrode coating layer by applying the electrode slurry on an electrolyte membrane; and drying the electrode coating layer.

Description

Electrode slurry for forming an electrode coating layer and a membrane-electrode assembly manufacturing method for a fuel cell using the same

The present invention relates to a membrane-electrode assembly for a fuel cell, and more particularly, an electrode coating layer for minimizing defects while increasing process efficiency in the process of manufacturing a membrane-electrode assembly for a fuel cell through a direct coating process It relates to an electrode slurry for forming and a method for manufacturing a membrane-electrode assembly for a fuel cell using the same.

In general, a fuel cell system is a kind of power generation system that directly converts chemical energy applied on a fuel film into electrical energy in a fuel cell stack without converting it into heat by combustion.

A fuel cell system is largely composed of a fuel cell stack that generates electrical energy, a fuel supply system that supplies fuel (hydrogen) to the fuel cell stack, an air supply system that supplies oxygen in the air, which is an oxidizing agent required for electrochemical reactions, to the fuel cell stack, and It consists of a heat and water management system that removes the reaction heat of the fuel cell stack to the outside of the system and controls the operating temperature of the fuel cell stack.

In such a fuel cell system, electricity is generated by an electrochemical reaction between hydrogen as a fuel and oxygen in the air, and heat and water are discharged as reaction byproducts.

A fuel cell stack is an electrical energy generating device in which unit cells are repeatedly stacked, and in this case, the unit cell is a minimum fuel cell component for generating electrical energy by reacting hydrogen and oxygen.

This unit cell structure is a stacked structure in the order of a membrane-electrode assembly (MEA), a gas diffusion layer (GDL), and a gasket.

Here, the membrane-electrode assembly for fuel cell is manufactured by coating an electrode slurry in which an active material, a conductive material, a binder, and a solvent are mixed on an electrolyte membrane in which hydrogen ions move, and then drying it at a high temperature. In this process, there was a problem in that the electrolyte membrane swells, causing the electrode to crack and cause a defect.

Accordingly, an object of the present invention is to provide an electrode slurry for forming an electrode coating layer to minimize defects caused by residual solvents or high-temperature conditions in the process of forming an electrode coating layer, and a method for manufacturing a membrane-electrode assembly for a fuel cell using the same. .

The method for manufacturing a membrane-electrode assembly for a fuel cell according to the present invention includes preparing an electrode slurry including an active material and an additive having a boiling point of 200° C. or higher, applying the electrode slurry on an electrolyte membrane to form an electrode coating layer, the electrode and drying the coating layer.

In the method for manufacturing a membrane-electrode assembly for a fuel cell according to the present invention, the additive comprises at least one of glycerol and 1,5-pentanediol.

In the method for manufacturing a membrane-electrode assembly for a fuel cell according to the present invention, the electrode slurry further comprises a conductive material and a binder.

In the method for manufacturing a membrane-electrode assembly for a fuel cell according to the present invention, the electrode slurry further comprises, after the drying step, the step of pressing the electrolyte membrane on which the electrode coating layer is formed through a press device.

The electrode slurry for forming the electrode coating layer according to the present invention is prepared by including an active material and an additive having a boiling point of 200° C. or higher.

In addition, the electrode slurry for forming an electrode coating layer according to the present invention and a method for manufacturing a membrane-electrode assembly for a fuel cell using the same, form the electrode coating layer through an electrode slurry containing an additive having a boiling point of 200° C. or higher, in the process of forming the electrode coating layer Defects caused by residual solvents or high-temperature conditions can be minimized.

1 is a flowchart illustrating a method for manufacturing a membrane-electrode assembly for a fuel cell using double-sided direct coating according to an embodiment of the present invention.
2 to 14 are views for explaining each step of the membrane-electrode assembly manufacturing method for a fuel cell using double-sided direct coating according to an embodiment of the present invention.

It should be noted that, in the following description, only the parts necessary for understanding the embodiments of the present invention will be described, and descriptions of other parts will be omitted in the scope not disturbing the gist of the present invention.

The terms or words used in the present specification and claims described below should not be construed as being limited to their ordinary or dictionary meanings, and the inventors have appropriate concepts of terms to describe their invention in the best way. It should be interpreted as meaning and concept consistent with the technical idea of the present invention based on the principle that it can be defined in Accordingly, the embodiments described in this specification and the configurations shown in the drawings are only preferred embodiments of the present invention, and do not represent all of the technical spirit of the present invention, so various equivalents that can be substituted for them at the time of the present application It should be understood that there may be variations and variations.

1 is a flow chart showing a method for manufacturing a membrane-electrode assembly for a fuel cell using double-sided direct coating according to an embodiment of the present invention, and FIGS. 2 to 14 are a fuel cell membrane using double-sided direct coating according to an embodiment of the present invention- It is a diagram for explaining each step of the electrode assembly manufacturing method.

First, in step S10, as shown in FIG. 2 , a flat plate 90 is prepared, and as shown in FIG. 3 , the first electrolyte membrane 10 is placed on one surface 91 of the flat plate 90 . make it Here, the flat plate 90 may be a hot plate capable of setting a temperature. That is, by controlling the temperature of the flat plate 90, it is possible to dry the first and second electrode coating layers 52 and 152 in steps S40 or S80 to be described later.

At this time, the first electrolyte membrane 10 includes an ion conductor. The ion conductor may be a cation conductor having a cation exchange group capable of transporting a cation such as a proton, or an anion conductor having an anion exchange group capable of transporting an anion such as a hydroxy 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 boronic acid group, a phosphoric acid group, an imide group, a sulfonimide group, a sulfonamide group, and combinations thereof, and generally a sulfonic acid group or a carboxyl group. .

The cationic conductor includes a fluorine-based polymer including the cation exchange group and containing fluorine in its main chain; Benzimidazole, polyamide, polyamideimide, polyimide, polyacetal, polyethylene, polypropylene, acrylic resin, polyester, polysulfone, polyether, polyetherimide, polyester, polyethersulfone, polyetherimide, poly hydrocarbon-based polymers such as carbonate, polystyrene, polyphenylene sulfide, polyether ether ketone, polyether ketone, polyaryl ether sulfone, polyphosphazene or polyphenylquinoxaline; partially fluorinated polymers such as polystyrene-graft-ethylenetetrafluoroethylene copolymer or polystyrene-graft-polytetrafluoroethylene copolymer; sulfone imides and the like.

More specifically, when the cation conductor is a hydrogen ion cation conductor, 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 the side chain, and the specific Examples include poly(perfluorosulfonic acid), poly(perfluorocarboxylic acid), copolymers of tetrafluoroethylene containing sulfonic acid groups and fluorovinylethers, defluorinated sulfided polyetherketones or mixtures thereof fluorine-based polymers; Sulfonated polyimide (S-PI), sulfonated polyarylethersulfone (S-PAES), sulfonated polyetheretherketone (SPEEK), sulfonated polybenzimi Sulfonated polybenzimidazole (SPBI), sulfonated polysulfone (S-PSU), sulfonated polystyrene (S-PS), sulfonated polyphosphazene, sulfonated poly Sulfonated polyquinoxaline, sulfonated polyketone, sulfonated polyphenylene oxide, sulfonated polyether sulfone, sulfonated polyether ketone polyether ketone), sulfonated polyphenylene sulfone, sulfonated polyphenylene sulfide, sulfonated polyphenylene sulfide sulfone, sulfonated polyphenyl Sulfonated polyphenylene sulfide sulfone nitrile, sulfonated polyarylene ether, sulfonated polyarylene ethernitrile, sulfonated polyarylene ether nitrile polyarylene ether ether nitrile), polyarylene ether sulfone ketone (sulfonated polyarylene ether sulfone ketone), and mixtures thereof and a hydrocarbon-based polymer including water, but is not limited thereto.

Anionic conductors are polymers capable of transporting anions such as hydroxy ions, carbonates or bicarbonates. Anionic conductors are commercially available in the hydroxide or halide (usually chloride) form, and anion conductors are industrial water (water) conductors. purification), metal separation or catalytic processes, and the like.

As the anion conductor, a polymer doped with a metal hydroxide may be generally used, and specifically, poly(ethersulfone) doped with a metal hydroxide, polystyrene, vinyl-based polymer, poly(vinyl chloride), poly(vinylidene fluoride), poly(tetrafluoroethylene), poly(benzimidazole), poly(ethylene glycol), or the like may be used.

Next, in step S20 , as shown in FIG. 4 , the first sub gasket 30 is attached on the first electrolyte membrane 10 . That is, in step S20, a film-shaped sub gasket 30 is attached on the first electrolyte membrane 10 to secure a space in which the first electrode coating layer 52 is formed.

Here, the sub gasket 30 is a heat-resistant base film that is at least one of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polyethylene (PE), and polypropylene (PP). may include

In addition, the sub gasket 30 may further include a thermally expansible pressure-sensitive adhesive layer that is at least one of an acrylic pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, a vinyl alkyl ether-based pressure-sensitive adhesive, and a silicone-based pressure-sensitive adhesive applied to one surface of the base film.

Next, in step S30 as shown in FIGS. 5 and 6 , the electrode slurry 50 is applied on the first electrolyte membrane 10 to which the first sub gasket 30 is attached, and the first electrode coating layer 52 is ) can be formed.

Here, the electrode slurry 50 may be mixed with an active material, a conductive material, a binder, carbon powder, and an organic solvent.

Carbon black or activated carbon may be used as the carbon powder used, and the particle size may be 5 nm to 10 μm. And as the organic solvent, one or a mixture of two or more selected from alcohols such as isopropanol, propanol, ethanol, and methanol may be used.

In particular, in the electrode slurry 50 according to the embodiment of the present invention, an additive having a boiling point of 200° C. or higher may be added to the organic solvent. In this case, as an additive of the organic solvent, at least one of glycerol and 1,5-pentanediol may be included. In this case, the glycerol may include 1 to 20% by weight based on the total weight. Accordingly, by adding at least one of glycerol and 1,5-pentanediol to the electrode slurry, defects caused by residual solvent or high temperature conditions in the process of forming the electrode coating layer can be minimized. .

In addition, the electrode slurry 50 may further include a polymer adhesive to increase adhesion during application, and the polymer adhesive includes a polymer electrolyte material having hydrogen ion conductivity, such as perfluorosulfonic acid, PTFE or hydrocarbon. A polymer adhesive can be used.

s가 되도록 유기 용매를 적정량 첨가하여 조정할 수 있다. 전극 슬러리(50)의 점도가 100 m㎩

s를 하회하면 닥터 블레이드로(70)의 외부로 전극 슬러리(50)가 유출되고, 2000 m㎩

s를 초과하면 닥터 블레이드(70)에 의해 시트화할 때에 저항이 커져서 표면에 요철이 발생할 수 있어 원활히 시트화할 수 없게 된다.The viscosity of the electrode slurry 50 is 100 to 2000 mPa

It can be adjusted by adding an appropriate amount of an organic solvent so that it may become s. The viscosity of the electrode slurry 50 is 100 mPa

When it is less than s, the electrode slurry 50 flows out of the doctor blade furnace 70, and 2000 mPa

If s is exceeded, the resistance increases when forming a sheet by the doctor blade 70, and irregularities may occur on the surface, making it impossible to form a sheet smoothly.

In addition, since the air contained in the electrode slurry 50 may have irregularities or reduce homogeneity when applied, it is preferable to degas the contained air by centrifugal degassing or vacuum degassing.

The electrode slurry 50 may be applied in the release mold 30 attached to the first electrolyte membrane 10 using the doctor blade 70 to form the electrode coating layer 52 . The electrode coating layer 52 formed here may have a thickness of 5 μm to 100 μm, which corresponds to the thickness of the release mold 30 .

The electrode slurry 50 is coated with the electrode slurry 50 in an equal thickness in the sub gasket 30 attached to the first electrolyte membrane 10 by the movement of the doctor blade 70 to form the electrode coating layer 52 . to form

Next, the first electrode coating layer 52 is dried in step S40. Here, various drying methods such as hot air drying, vacuum drying, infrared (IR) drying, etc. may be applied to the drying, and the drying temperature and time may be appropriately adjusted according to the boiling point (BP) of the solvent used. For example, the drying temperature may be drying at 60° C. to 150° C. for 05 hours to 10 hours. If the drying temperature is less than 60 ℃ or the drying time is less than 05 hours, the swelling solvent may remain inside the polymer electrolyte membrane, or a sufficiently dried catalyst layer may not be formed. The membrane may receive chemical damage such as browning, or cracks may occur in the catalyst layer. After the step S40, the sub gasket 30 may be removed while the first electrode coating layer 52 is dry.

Next, in step S50, as shown in FIGS. 7 to 9 , after rotating the flat plate 90 , the second electrolyte membrane 110 is positioned on the other surface 92 of the flat plate 90 .

Next, as shown in FIG. 10 in step S60 , the second sub gasket 130 is attached on the second electrolyte membrane 110 . That is, in step S60, the sub gasket 130 in the form of a film is attached on the second electrolyte membrane 10 to secure a space in which the second electrode coating layer 152 is formed.

Next, in step S70, as shown in FIGS. 11 and 12 , the electrode slurry 50 is applied on the second electrolyte membrane 110 to which the second sub gasket 130 is attached to thereby the second electrode coating layer 152 . ) can be formed.

Next, the second electrode coating layer 152 is dried in step S80 , and the second sub gasket 130 may be removed as shown in FIG. 13 .

And as shown in FIG. 14 in step S90, the first electrode coating layer 52 and the second electrode coating layer 152 may be compressed through the press device 80 . Here, the press device 80 may be a device capable of a hot press process. Here, the hot press refers to a process of compressing the first electrode coating layer 52 and the second electrode coating layer 152 under conditions of high temperature and high pressure by applying heat and pressure.

As described above, in the method for manufacturing a membrane-electrode assembly for a fuel cell using double-sided direct coating according to an embodiment of the present invention, direct coating is performed on the electrolyte membrane, and both surfaces of the flat plate are directly coated through the rotation of the flat plate. Cost reduction may be possible by shortening process time and reducing manpower.

In addition, the method for manufacturing a membrane-electrode assembly for a fuel cell using double-sided direct coating according to an embodiment of the present invention can minimize defects caused by residual solvent or high-temperature conditions in the process of forming the electrode coating layer by adding glycerol. .

On the other hand, the embodiments disclosed in the present specification and drawings are merely presented as specific examples to aid understanding, and are not intended to limit the scope of the present invention. It is apparent to those of ordinary skill in the art to which the present invention pertains that other modifications based on the technical spirit of the present invention can be implemented in addition to the embodiments disclosed herein. In addition, although specific terms have been used in the present specification and drawings, these are only used in a general sense to easily explain the technical contents of the present invention and help the understanding of the present invention, and are not intended to limit the scope of the present invention.

10: first electrolyte membrane
30: first sub gasket
50: electrode slurry
52: first electrode coating layer
70 : Doctor Blade
90: flat plate
110: second electrolyte membrane
130: second sub gasket
152: second electrode coating layer

Claims (5)

preparing an electrode slurry including an active material and an additive having a boiling point of 200° C. or higher;
forming an electrode coating layer by applying the electrode slurry on an electrolyte membrane;
drying the electrode coating layer;
A fuel cell membrane-electrode assembly manufacturing method comprising a. According to claim 1,
The additive is
A membrane-electrode assembly manufacturing method for a fuel cell, comprising at least one of glycerol and 1,5-pentanediol. According to claim 1,
The electrode slurry,
Membrane-electrode assembly manufacturing method for fuel cell, characterized in that it further comprises a conductive material and a binder. According to claim 1,
The electrode slurry,
After the drying step,
compressing the electrolyte membrane on which the electrode coating layer is formed through a press device;
Membrane-electrode assembly manufacturing method for fuel cell, characterized in that it further comprises. An electrode slurry for forming an electrode coating layer applied to a fuel cell-membrane-electrode assembly prepared by including an active material and an additive having a boiling point of 200° C. or higher.

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