KR100805458B1 - A one body type membrane electrode assembly with gasket of multiple sealing structure for a fuel cell - Google Patents

Abstract

A membrane-electrode assembly formed integrally to a gasket having a multiple sealing structure for a fuel cell is provided to improve the assemblage rate, to minimize contamination of a membrane-electrode assembly caused by leakage of an anti-freezing agent, and to increase the interfacial adhesion between a membrane-electrode assembly and a gas diffusion layer. A membrane-electrode assembly(110) includes a polymer electrolyte membrane(112) having a reaction gas manifold and a cooling water manifold for sucking and discharging reaction gases and cooling water, and catalyst layers(114) of a cathode and an anode bonded to both surfaces of the polymer electrolyte membrane. The membrane-electrode assembly further comprises: a gas diffusion layer(120) bound to both surfaces of the membrane-electrode assembly for dispersing the reaction gases uniformly over the membrane-electrode assembly; and at least one gasket(130,140) formed integrally to the membrane-electrode assembly corresponding to the shape of the membrane-electrode assembly for preventing leakage of the cooling water.

Description

A one body type membrane electrode assembly with gasket of multiple sealing structure for a fuel cell}

1 is a plan view showing a separator plate formed with a conventional single hermetic gasket.

FIG. 2 is a perspective view illustrating an assembly process of a membrane-electrode assembly, a gasket, and a separator according to FIG. 1; FIG.

3 is a plan view showing a separator plate formed with a conventional double hermetic gasket.

4 is a perspective view illustrating an assembly process of the membrane-electrode assembly and the gasket and the separator according to FIG. 3.

5 is a cross-sectional view illustrating a gasket integrated membrane-electrode assembly of a multi-tight structure according to the present invention.

6 is a partial perspective view of the membrane-electrode assembly according to FIG. 5.

FIG. 7 is a perspective view illustrating an assembly process of a membrane-electrode assembly, a gasket, and a separator according to FIG. 5; FIG.

* Explanation of symbols for the main parts of the drawings

100 unit cell 110 membrane-electrode assembly

112 polymer electrolyte membrane 114 catalyst electrode layer

120: gas diffusion layer 130: primary gasket

140: secondary gasket 150: sub gasket

160: separator

The present invention relates to a multi-sealed gasket-integrated membrane-electrode assembly for fuel cells, and more particularly, to a fuel cell multi-sealed-sealed gasket-integrated membrane integrated with a gas-tight layer and a membrane-electrode assembly instead of a separator. It is about an electrode assembly.

The membrane-electrode assembly (MEA) of the fuel cell is composed of a polymer electrolyte membrane, a gas diffusion layer, and an electrode (anode and cathode). When hydrogen supplied to the cathode is separated into hydrogen ions and electrons, the separated hydrogen ions move to the anode through the electrolyte layer and the electrons move to the anode through an external circuit. At the anode side, oxygen molecules and hydrogen ions meet to generate electricity and heat, while producing water as a reaction product.

1 is a plan view illustrating a separator plate formed with a conventional gasket having a single hermetic structure, and FIG. 2 is a perspective view illustrating an assembly process of the membrane-electrode assembly and the gasket and the separator according to FIG. 1.

As shown in FIG. 2, a membrane-electrode assembly generally used is a three-layer MEA (three-layer Membrane Electrode Assembly, 1), and is formed by bonding two electrodes, a cathode and an anode, on both sides of a polymer electrolyte membrane. However, this three-layer MEA (1) has a disadvantage in that the work process and time increase because the gas diffusion layer (3) and the gasket (5) and the separation plate (7) must be further bonded when assembling the fuel cell stack (hereinafter referred to as MEA). And a membrane-electrode assembly.

In addition, since these components are not in an integrated form, the assembly process is mostly performed by hand, and if the arrangement between components is incorrect or uneven, the overall performance may be degraded after assembling the fuel cell stack.

In the case of fuel cells used in automobiles, since they must operate normally under the conditions of the image and sub-zero temperature, antifreeze is used instead of the coolant used in the fuel cell. However, as shown in FIG. 1, the conventional three-layer MEA 1 uses a gasket 5 of a single hermetic structure, which contaminates the membrane-electrode assembly 1 upon leakage of the antifreeze.

In order to compensate for the shortcomings of the 3 layer MEA, a 5 layer MEA has been developed and used.

3 is a plan view illustrating a separator formed with a conventional double hermetic gasket, and FIG. 4 is a perspective view illustrating an assembly process of the membrane-electrode assembly and the gasket and the separator according to FIG. 3.

As shown in FIG. 4, the 5-layer MEA 2 is formed by bonding the gas diffusion layers 4 to both sides of the 3-layer MEA 1 and integrating them. After that, the fuel cell stack is assembled by combining the separator 8 having the gasket 6 integrated on both sides of the 5 layer MEA 2.

In this case, as shown in FIG. 3, a dual structure gasket 6 including a primary gasket 6a and a secondary gasket 6b is formed on the separator 8 to prevent contamination by antifreeze. . However, since the conventional gasket 6 having a double structure is bonded onto the separator 8, there is no effect of contributing to the improvement of the interface bonding force between the membrane-electrode assembly 1 and the gas diffusion layer 4.

Therefore, there is a need to develop a method for minimizing the contamination of the antifreeze for cooling, improving the interfacial bonding between the membrane-electrode assembly and the gas diffusion layer, and at the same time simplifying the stack assembly process.

The object of the present invention is to improve the assembly speed by integrating a multi-sealed gasket into a membrane-electrode assembly and a gas diffusion layer instead of a separator plate, and contaminates the membrane-electrode assembly due to leakage of a cooling antifreeze used in an automobile fuel cell. It is to provide a multi-sealing gasket-integrated membrane-electrode assembly for a fuel cell that can minimize stack performance degradation and increase the interfacial bond between the membrane-electrode assembly and the gas diffusion layer.

In order to achieve the above object, the present invention provides a membrane-electrode assembly in which a catalyst electrode layer of an anode and a cathode is respectively coupled to both sides of a polymer electrolyte membrane in which a reaction gas manifold and a coolant manifold in which reactant gas and coolant are intaken and exhausted are formed. The film-electrode assembly may be integrally formed on both sides of the membrane-electrode assembly and integrally formed in the gas diffusion layer and the membrane-electrode assembly to uniformly disperse the reaction gas in the membrane-electrode assembly. Provided is a multi-sealing gasket-integrated membrane-electrode assembly for a fuel cell, characterized in that it comprises at least one gasket formed corresponding to the shape of the assembly.

The gasket is formed to correspond to the shape of the coolant manifold and is formed to correspond to the shape of the membrane-electrode assembly and the first gasket sealing the periphery of the coolant and the membrane-electrode assembly. And a second gasket sealing between the manifold and the gas diffusion layer.

The gasket is formed along the edge of the membrane-electrode assembly and the edge of the manifold, and is inserted into the lower portion of the first gasket and the second gasket, and has a width wider than that of the first gasket and the second gasket. It characterized in that it further comprises.

The gas diffusion layer is formed integrally with the membrane-electrode assembly by thermocompression under conditions of 1 to 20 minutes at 70 to 100 ° C.

The first gasket and the second gasket are formed by using any one of a durable and elastic fluorine-based or silicon-based material in the liquid phase.

The first gasket and the second gasket are formed by forming the liquid fluorine-based or silicon-based material on the sub-gasket and thermally curing at 110 to 160 ° C. for 5 to 60 minutes.

The first gasket and the second gasket have a Shore hardness of 40 A to 80 A after thermal curing, and a permanent compressive strain of less than 30 after 1000 hours at 120 ° C.

Hereinafter, a fuel cell using a perfluorinated sulfuric acid-based polymer material as a polymer electrolyte membrane will be described as an embodiment of the present invention, and a multi-sealed gasket-integrated membrane-electrode assembly for a fuel cell of the present invention will be described in detail with reference to the accompanying drawings. do.

5 is a cross-sectional view showing a gasket-integrated membrane-electrode assembly of a multi-tight structure according to the present invention, FIG. 6 is a partial perspective view of the membrane-electrode assembly according to FIG. 5, and FIG. It is a perspective view which shows the assembly process of an electrode assembly, a gasket, and a separator.

As shown in FIGS. 5 to 7, the membrane-electrode assembly 112 of the present invention is used in combination with a Membrane Electrode Assembly (hereinafter referred to as MEA) or a catalyst electrode layer 114 on both sides of the polymer electrolyte membrane 112. The gas diffusion layer 120 is compressed, and the separator 160 is coupled to the outside thereof. In addition, double-sealed gaskets 130 and 140 are formed in the membrane-electrode assembly 110 and the gas diffusion layer 120 to which the sub-gasket 150 is bonded, and the assembly thereof is a unit of the fuel cell. The battery 100 is formed.

6 and 7, the polymer electrolyte membrane 112 of the membrane-electrode assembly 110 includes an intake and exhaust manifold 112a through which the reaction gas is intaken and exhausted and a coolant manifold through which the coolant is intaken and exhausted ( 112b) are formed respectively.

The gas diffusion layer 120 is compressed on both sides of the membrane-electrode assembly 110, and the gas diffusion layer 120 uniformly disperses the reaction gas supplied from the separator plate in the membrane-electrode assembly 110 and generates a reaction. It removes water and humidified water and also acts as a mobile conductor of electrons generated during electrochemical reactions.

When the gas diffusion layer 120 is placed on both sides of the membrane-electrode assembly 110 and thermally compressed by a hot press device, the gas diffusion layer 120 is physically coupled to the membrane-electrode assembly 110. At this time, in order to obtain the performance of the uniform membrane-electrode assembly 110, it is important to set the optimum crimping conditions so that the overall bonding between the MEA 110 and the gas diffusion layer 120 occurs well.

According to an embodiment of the present invention, the perfluorinated sulfuric acid-based polymer electrolyte membrane 112 has a glass transition temperature of 100 to 120 ° C. according to a molecular structure, and heats the MEA 110 itself at a high temperature for a long time. May cause deformation and deterioration. Therefore, the gas diffusion layer 120 is preferably thermocompressed for 1 to 20 minutes in the temperature range of 70 ~ 100 ℃.

Fuel cells used in automobiles must operate normally under sub-zero temperatures, so antifreeze is used instead of cooling water. A general antifreeze currently in use may cause degradation of the membrane-electrode assembly 110 when it comes into contact with the membrane-electrode assembly 110, thereby degrading the performance of the fuel cell. Therefore, in order to prevent leakage of the antifreeze, a dual-structured gasket 130 and 140 will be used.

As shown in FIG. 5 and FIG. 6, the gas diffusion layer 120 is press-bonded to the membrane-electrode assembly 110 to form a gasket 130 and 140 having a double structure to secure airtightness.

The gaskets 130 and 140 include a first gasket 130 for sealing around the coolant manifold 112b and a second gasket 140 for sealing around the MEA 110 edge and the reactive gas manifold 112a. do. At this time, if necessary, the rigid sub-gasket 150 may be additionally used.

The first gasket 130 is made to correspond to the shape of the coolant manifold 112b and is formed along the coolant manifold 112b to prevent leakage of the antifreeze used as the coolant.

The second gasket 140 is formed to correspond to the shape of the membrane-electrode assembly 110 except for the coolant manifold 112b and is formed along the edge of the MEA 110 and the edge of the coolant manifold 112b. . When the second gasket 140 leaks an antifreeze that may be present, the second gasket 140 serves to discharge it to the outside of the membrane-electrode assembly 110 once again.

The first gasket 130 and the second gasket 140 are molded using a liquid material rather than a solid. In order to maintain durability and hermetic structure for a long time in various fuel cell driving environments, the chemical resistance to acid, water and antifreeze must be excellent and elasticity must be excellent. Materials satisfying these characteristics include fluorine-based or silicon-based polymer materials.

The fluorine- or silicon-based polymer material is prepared in a liquid state, and a 5 layer MEA (combined gas diffusion layer to a 3 layer MEA in which a catalyst electrode layer is bonded to a polymer electrolyte membrane) is placed in a gasket forming mold, and then placed on the 5 layer MEA 110. The first gasket 130 and the second gasket 140 are shaped.

The molding of the liquid gaskets 130 and 140 is determined in consideration of the glass transition temperature of the polymer electrolyte membrane 112 and is preferably thermally cured for 5 to 60 minutes in the temperature range of 110 to 160 ° C. The heat-hardened gaskets 130 and 140 have a shore hardness of 40A to 80A, and a permanent compression set of less than 30% after heat treatment at 120 ° C. for 1000 hours.

The double-structured gaskets 130 and 140 may be converted into multiple structures as necessary, and in addition to the double hermetic effect, the membrane-electrode assembly 110 and the gas diffusion layer 120 may be formed by the second gasket 140. The effect that the interfacial bonding force of the liver increases can also be obtained.

The sub-gasket 150 is formed before the first gasket 130 and the second gasket 140 is formed, if necessary, it is preferably provided with a rigid material. The sub-gasket 150 is made to correspond to the shape of the MEA 110 and is formed along the edges of the MEA 110 and the edges of the respective manifolds 112a and 112b. The sub gasket 150 is thinner than the first gasket 130 and the second gasket 140 and is formed to have a wide width.

That is, the sub gasket 150 is positioned below the first gasket 130 and the second gasket 140 to seal the membrane electrode assembly 110 once more. In addition, since the sub-gasket 150 complements the strength of the membrane-electrode assembly 110 and simultaneously serves as a sealing role, the sub-gasket 150 serves to improve stacking workability and convenience of the fuel cell stack.

As illustrated in FIG. 7, the unit cell 100 having such a configuration includes a membrane-electrode assembly 110 in which a polymer electrolyte membrane 112 and a catalyst electrode layer 114 are combined, a gas diffusion layer 120, and a first electrode. The gasket 130 and the second gasket 140 and the sub gasket 150 are integrally formed as needed, and are made by combining the separator 160.

The conventional unit cell illustrated in FIG. 2 requires a total of six separate assembly processes by bonding a total of seven components, and the conventional unit cell illustrated in FIG. 4 combines a total of five components, respectively. Four separate assembly processes are required. Therefore, conventionally, there is a problem that the production speed of the fuel cell stack is greatly reduced during mass production.

On the contrary, since the unit cell 100 of the present invention only needs to assemble a total of three parts twice, the assembly and manufacturing process can be drastically shortened when the fuel cell stack composed of hundreds of unit cells 100 per vehicle is mass-produced. There is an advantage that can greatly increase the speed. The assembly process is simple and the number of assembly parts is reduced, which helps to automate the fuel cell stack assembly process.

Meanwhile, the present invention is not limited to the above-described embodiments, and any person having ordinary skill in the art to which the present invention pertains may make various modifications without departing from the gist of the present invention as claimed in the claims. Of course, such changes will fall within the scope of the claims set forth.

As described above, the membrane-electrode assembly integrated with a gas-tight structure for a fuel cell according to an embodiment of the present invention reduces the number of assembly processes by integrating the gas-tight layer with the membrane-electrode assembly and the gas diffusion layer instead of the separator. The assembly speed is improved, and automation can be easily implemented.

In addition, since the gasket is formed in a multiple structure, there is an effect of minimizing the contamination of the membrane-electrode assembly due to the leakage of the antifreeze for cooling and the deterioration of the performance of the fuel cell stack.

Furthermore, the multi-layer structure of the gasket increases the interfacial bonding force between the membrane-electrode assembly and the gas diffusion layer, thereby contributing to long-term durability.

Claims (7)

Membrane-electrode in which the anode and cathode catalyst electrode layers 114 are respectively coupled to both surfaces of the polymer electrolyte membrane 112 on which the reaction gas manifold 112a and the coolant manifold 112b, through which the reactant gas and the coolant are intaken and exhausted, are formed. In the conjugate 110, Is integrally formed on the gas diffusion layer 120 and the membrane-electrode assembly 110 are respectively coupled to both sides of the membrane-electrode assembly 110 to uniformly disperse the reaction gas in the membrane-electrode assembly 110, And a gas-tight structure gasket-integrated membrane-electrode assembly for fuel cells, characterized in that it comprises at least one gasket (130, 140) formed corresponding to the shape of the membrane-electrode assembly (110) to prevent leakage of cooling water. The method of claim 1, The gaskets 130 and 140 are formed to correspond to the shape of the coolant manifold 112b, and seal the periphery of the coolant manifold 112b and the membrane-electrode assembly 110. The fuel is characterized in that it comprises a second gasket 140 formed corresponding to the shape and sealing the edge of the membrane-electrode assembly 110 and the reaction gas manifold 112a and the gas diffusion layer 120. Multi-sealed gasket-integrated membrane-electrode assembly for batteries. The method of claim 2, The gaskets 130 and 140 are formed along the edges of the membrane-electrode assembly 110 and the edges of the manifolds and are inserted below the first gasket 130 and the second gasket 140. The gasket 130 and the gasket integral membrane-electrode assembly for a fuel cell, characterized in that it further comprises a sub-gasket (150) having a width wider than the width of the second gasket (140). The method of claim 1, The gas diffusion layer 120 is integrally formed with the membrane-electrode assembly 110 by thermocompression bonding under conditions of 1 to 20 minutes at 70 to 100 ° C. Conjugate. The method of claim 2, The first gasket 130 and the second gasket 140 may be formed by using any one of a durable and elastic fluorine-based or silicon-based material in a liquid phase. . The method of claim 5, The first gasket 130 and the second gasket 140 are formed by molding the liquid fluorine-based or silicon-based material on the sub-gasket 150 and thermally curing at 110 to 160 ° C. for 5 to 60 minutes. A membrane-electrode assembly with multiple hermetic structure gaskets for fuel cells. The method of claim 6, The first gasket 130 and the second gasket 140 have a Shore hardness of 40A to 80A after thermal curing, and a permanent compression strain of less than 30% after 1000 hours at 120 ° C. Integral membrane-electrode assembly.

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