KR102312860B1 - Modular gaskets for fuel cell, membrane electrode assembly having the modular gaskets, and method for manufacturing the modular gaskets - Google Patents

Abstract

The present invention relates to a modular gasket of a fuel cell, a membrane electrode assembly having the modular gasket, and a manufacturing method of the modular gasket. The task to be solved is to have the same airtight properties as a bipolar plate (BP) gasket on the upper surface of a sub-gasket used in a membrane electrode assembly (MEA) and to maintain airtightness even if the existing BP gasket is not used by applying modified liquid silicone rubber (LSR) to improve acid resistance through coating or injection, etc. For example, disclosed is a membrane electrode assembly of a fuel cell, comprising: an MEA with a three-layer structure in which an anode, a membrane, and a cathode are stacked; a modular gasket including sub-gaskets respectively formed on both sides of the MEA and a main gasket formed by coating and curing modified LSR in which silane containing fluorine is mixed with LSR is coated on the sub-gasket; and current collectors separately formed on the main gasket and electrically connected to the anode and the cathode, respectively.

Description

A modular gasket of a fuel cell, a membrane electrode assembly having a modular gasket, and a method for manufacturing a modular gasket

An embodiment of the present invention relates to a modular gasket for a fuel cell, a membrane electrode assembly having a modular gasket, and a method for manufacturing the modular gasket.

Membrane-Electrode Assembly (MEA) is formed in the central part of the polymer electrolyte fuel cell, and the structure of this membrane electrode assembly forms a three-layer structure of anode-membrane-cathode. It is called '3layer' or 'MEA3', and it is called '5Layer' or 'MEA5' because a sub-gasket is added to the outer part of the electrode layer.

The '5Layer' or 'MEA5' configured in this way is combined with the BP (Bipolar Plate) gasket to supply fuel to the central part where the oxidation/reduction reaction takes place, and when the water generated by the reaction is discharged, it is fueled to the side part of the MEA. It acts as a sealing so that water does not leak.

The gasket for BP (Bipolar Plate) used in the fuel cell stack must have excellent elasticity and low compression set in an appropriate range of hardness, and the pH2 generated when the fuel cell is driven Acid resistance, hydrolysis resistance, and gas permeability resistance that do not cause deformation even in an acidic atmosphere of

In general, fluorine-based, silicon-based, and hydrocarbon-based materials are widely used as constituent materials of gaskets for fuel cell BP (Bipolar plate).

In the case of a gasket for fluorine-based BP (bipolar plate), it has a structure with fluoride attached to the molecular structure and has excellent elasticity, acid resistance, and heat resistance. , is produced by injection molding, so productivity is low, cold resistance is not good, and the price of the material is high, so its use is limited. In order to improve the cold resistance of fluorine-based BP (Bipolar plate) gaskets, a material that can be crosslinked with peroxide to secure airtight properties even at -30 degrees has been developed, but the disadvantage is that the price is higher, and airtightness is still maintained at -40 degrees or less Currently, most manufacturers do not employ it.

In the case of hydrocarbon-based gaskets for BP (Bipolar plate), EPDM (Ethylene Propylene Diene Monomer), EPR (Ethylene Propylene Rubber), IR (Isoprene Rubber), etc. are widely used. While excellent in cold resistance of -40 degrees, There is a problem in that elasticity and oxidation resistance are lowered upon exposure, resulting in leakage.

For silicone-based BP (Bipolar plate) gaskets, general types such as PDMS (Polydimethylsiloxane) and expensive modified silicone containing fluoride are easy to secure mechanical and chemical properties, but LSR (Liquid Silicone Rubber) I use it a lot. These silicone rubbers have excellent processability, heat resistance, and a wide range of operating temperature conditions, so they were often applied in the early development stage of the hydrogen fuel cell stack. It contaminates the same catalyst surface, reducing fuel cell efficiency. Therefore, in order to use LSR (Liquid Silicone Rubber), it is necessary to apply modified silicone with improved acid resistance.

On the other hand, in the conventional stacking process for fuel cells, a method of stacking a rubber gasket in the form of a band or O-ring manufactured by injection in advance is fixed on a BP (Bipolar plate) and stacked. BP (Bipolar plate) Because the gasket is made of rubber, it is difficult to apply the automated process due to the characteristics of the material, which can be easily bent, resulting in lower productivity and higher manufacturing cost.

Registered Patent Publication No. 10-0501682 (Registration Date: July 06, 2005) Laid-open Patent Publication No. 10-2008-0071319 (published date: August 04, 2008) Laid-open Patent Publication No. 10-2018-0126708 (published date: November 28, 2018)

In an embodiment of the present invention, BP (Bipolar Plate) used to secure airtightness between BP (Bipolar Plate) and MEA (Membrane-Electrode Assembly) whenever MEA (Membrane-Electrode Assembly) is stacked during the manufacture of a fuel cell stack ) gasket is made of rubber, and due to the nature of the material, it is difficult to apply an automated process, so productivity is reduced. To this end, modified LSR (Liquid Silicone Rubber), which has the same airtight properties as the BP (Bipolar Plate) gasket, and has secured acid resistance, is coated on the upper surface of the sub gasket used in MEA (Membrane-Electrode Assembly) through coating or injection methods. Provided are a modular gasket capable of maintaining airtightness even if the existing gasket for BP (Bipolar Plate) is not used by coating, a membrane electrode assembly having a modular gasket, and a method of manufacturing a modular gasket.

A modular gasket for a fuel cell according to an embodiment of the present invention includes: sub-gaskets respectively formed on both sides of a Membrane Electrode Assembly (MEA) having a three-layer structure in which an anode, a membrane, and a cathode are stacked; and a main gasket formed by coating and curing a modified LSR in which silane containing fluorine is mixed with liquid silicone rubber (LSR), respectively.

In addition, the modified LSR may be a single LSR or a mixture of two or more LSRs having different hardnesses to have a hardness of 30 to 70 (ASTM D2240, Shore A hardness).

In addition, the modified LSR may be prepared by using 1 part by weight or less of the silane.

In addition, each thickness of the main gasket may be 50 μm or more and less than 500 μm.

In addition, the sub gasket may include an adhesive layer formed on the MEA and including a thermosetting resin; and a base layer formed on the adhesive layer and including a polyimide (PI) or polyethylene naphthalate (PEN) film.

In addition, the thickness of the adhesive layer may be 5 μm or more and 100 μm or less.

In addition, the thickness of the base layer may be 10 μm or more and 70 μm or less.

Membrane electrode assembly of a fuel cell according to another embodiment of the present invention, a three-layer structure of the anode, the membrane and the cathode are stacked MEA (Membrane Electrode Assembly); Sub-gaskets respectively formed on both sides of the MEA, and a modified LSR in which silane containing fluorine is mixed with LSR (Liquid Silicone Rubber) is coated on the sub-gasket and then cured to form a main gasket. a modular gasket comprising; and current collectors respectively formed on the main gasket and electrically connected to the anode and the cathode, respectively.

In addition, the modified LSR may be a single LSR or a mixture of two or more LSRs having different hardnesses to have a hardness of 30 to 70 (ASTM D2240, Shore A hardness).

In addition, the modified LSR may be prepared by using 1 part by weight or less of the silane.

In addition, each thickness of the main gasket may be 50 μm or more and less than 500 μm.

In addition, the sub gasket may include an adhesive layer formed on the MEA and including a thermosetting resin; and a base layer formed on the adhesive layer and including a polyimide (PI) or polyethylene naphthalate (PEN) film.

In addition, the thickness of the adhesive layer may be 5 μm or more and 100 μm or less.

In addition, the thickness of the base layer may be 10 μm or more and 70 μm or less.

According to another embodiment of the present invention, a method for manufacturing a modular gasket for a fuel cell includes preparing a modified LSR by mixing silane containing fluorine with LSR (Liquid Silicone Rubber); Primer coating treatment on the surface of the substrate layer including the PI (Polyimide) or PEN (Polyethylene Naphthalate) film; forming a main gasket by coating and curing the modified LSR on the primer-coated base layer; and forming an adhesive layer including a thermosetting resin on a lower surface of the base layer to form a sub-gasket together with the base layer.

In addition, the modified LSR may be manufactured to have a hardness of 30 to 70 (ASTM D2240, Shore A hardness) by mixing a single LSR or two or more LSRs having different hardnesses.

In addition, the modified LSR may be prepared by using 1 part by weight or less of the silane.

In addition, the main gasket may be manufactured to have a thickness of 50 μm or more and less than 500 μm, respectively.

In addition, the adhesive layer may be manufactured to have a thickness of 5 μm or more and 100 μm or less, respectively.

In addition. The base layer may be manufactured to have a thickness of 10 μm or more and 70 μm or less, respectively.

According to the present invention, modified LSR (Liquid Silicone Rubber), which has the same air-tightness properties as the gasket for BP (Bipolar Plate), and has secured acid resistance, is coated on the upper surface of the sub-gasket used in MEA (Membrane-Electrode Assembly) by coating or injection. By providing a method for manufacturing a modular gasket, a membrane electrode assembly having a modular gasket, and a modular gasket that can be applied through the coating method and airtightness can be maintained even if the existing gasket for BP (Bipolar Plate) is not used, a fuel cell Whenever MEA (Membrane-Electrode Assembly) is stacked during stack manufacturing, the gasket for BP (Bipolar Plate) used to secure airtightness between BP (Bipolar Plate) and MEA (Membrane-Electrode Assembly) is made of rubber, so it can be easily Due to the nature of the bendable material, it is difficult to apply an automated process, which reduces productivity, and as a sub gasket and a separate BP (bipolar plate) gasket are additionally used, the problem of increased manufacturing cost can be solved.

1 is an exploded perspective view showing a membrane electrode assembly of a fuel cell according to an embodiment of the present invention.
2 is a perspective view showing a 3-layer MEA according to an embodiment of the present invention.
3 is a perspective view illustrating a 3-layer MEA to which a sub gasket is coupled according to an embodiment of the present invention.
4 is a perspective view illustrating a structure of a sub gasket according to an embodiment of the present invention.
5 is a view showing a cell for measuring the compression set of the main gasket according to an embodiment of the present invention.
6 is a graph showing the measurement of environmental resistance for Experimental Examples 1 to 3 and Comparative Examples 1 and 2 of the main gasket according to another embodiment of the present invention.
7 is a thermogravimetric (TGA) graph of a modified LSR according to an embodiment of the present invention.
8 is a graph showing the measurement of environmental resistance of a general LSR.
9 is a flowchart illustrating a manufacturing sequence of a modular gasket for a fuel cell according to another embodiment of the present invention.

Terms used in this specification will be briefly described, and the present invention will be described in detail.

The terms used in the present invention have been selected as currently widely used general terms as possible while considering the functions in the present invention, but these may vary depending on the intention or precedent of a person skilled in the art, the emergence of new technology, and the like. In addition, in a specific case, there is a term arbitrarily selected by the applicant, and in this case, the meaning will be described in detail in the description of the corresponding invention. Therefore, the term used in the present invention should be defined based on the meaning of the term and the overall content of the present invention, rather than the name of a simple term.

In the entire specification, when a part "includes" a certain component, it means that other components may be further included, rather than excluding other components, unless otherwise stated. In addition, terms such as "...unit" and "module" described in the specification mean a unit that processes at least one function or operation, which may be implemented as hardware or software, or a combination of hardware and software. .

Hereinafter, with reference to the accompanying drawings, embodiments of the present invention will be described in detail so that those of ordinary skill in the art can easily carry out the embodiments of the present invention. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

1 is an exploded perspective view showing a membrane electrode assembly of a fuel cell according to an embodiment of the present invention, FIG. 2 is a perspective view showing a three-layer MEA according to an embodiment of the present invention, and FIG. 3 is an embodiment of the present invention is a perspective view showing a three-layer MEA to which a sub gasket is combined, FIG. 4 is a perspective view showing the structure of a sub gasket according to an embodiment of the present invention, and FIG. 5 is a permanent compression of the main gasket according to an embodiment of the present invention. It is a view showing a reduction rate measuring cell, and FIG. 6 is a graph showing the measurement of environmental resistance of the main gasket according to an embodiment of the present invention for Experimental Examples 1 to 3 and Comparative Examples 1 and 2.

Referring to FIG. 1 , a membrane electrode assembly 1000 of a fuel cell according to an embodiment of the present invention includes an MEA 100 having a three-layer structure, a modular gasket 200 , and a current collector 300 .

The MEA 100 has a three-layer structure consisting of an anode 110 , a membrane 120 and a cathode 130 , and more specifically, between the anode 110 and the cathode 130 as shown in FIG. 2 . In a form in which the membrane 120 is interposed, a total of three layers may be stacked.

The modular gasket 200 may include a sub gasket 210 and a main gasket 220 .

As shown in FIG. 3 , the sub gasket 210 may be formed on an edge of the membrane 120 , excluding the anode 110 and the cathode 120 . As shown in FIG. 4 , the sub gasket 210 may have a two-layer structure including an adhesive layer 211 and a base film 212 .

The adhesive layer 211 may be formed on the MEA 100 and coated with a thermosetting resin.

The thickness of the adhesive layer 211 is preferably 5 μm or more and 100 μm or less, and more preferably 10 μm to 50 μm. When the thickness of the composition of the adhesive layer 211 is 5 μm or less, sealing may not be performed normally between the electrolyte membrane and the base layer 212 and leakage may occur, and when the thickness is 50 μm or more, the electrolyte membrane In the process of adhering the base layer 212 to the adhesive composition, a problem in which the adhesive composition leaks out may occur.

The base film 212 may be generally a PET film, but in this embodiment, a PI (Polyimide) or PEN (Polyethylene Naphthalate) film having excellent mechanical and chemical properties is preferably applied. As will be described later, the modified LSR (Liquid Silicone Rubber) is coated on the base layer 212 to dry it. phenomena can occur. In this embodiment, in order to improve this desorption phenomenon, the surface on the base layer 212 is modified before the formation (coating) of the modified LSR so that the modified LSR does not fall off even if it is coated/dried, a more detailed description thereof will be described later. do.

The thickness of the base layer 212 is preferably 10 to 100 μm, more preferably 10 μm or more and 70 μm or less. When a film of 10 μm or less is used to form the base layer 212, the gas diffusion layer (GDL) is compressed when the fuel cell is fastened, and fuel supply is not provided, so there is a problem that the overall performance of the battery is lowered. , when a film of 70 μm or more is used, the gas diffusion layer (GDL) is present in a floating state between the bipolar plates (BP), and the resistance with the current collector 300 increases, thereby deteriorating the performance of the battery.

The main gasket 220 may be formed by coating a modified LSR in which silane containing fluorine is mixed with liquid silicone rubber (LSR) is coated on the sub gasket 210 and then cured.

The modified LSR is a single LSR or a mixture of two or more LSRs with different hardnesses, and is manufactured to a hardness of 30 to 70 (ASTM D2240, Shore A hardness) (or EPDM (Ethylene Propylene Diene Terpolymer) can also be used instead of LSR) it is preferable A typical fuel cell stack consists of hundreds of MEA and BP (bipolar plate), and since airtightness must be maintained through uniform surface contact between parts, it is important to control appropriate hardness. If the hardness of the modified LSR applied on the sub gasket 210 is 70 or more, it is too hard to secure airtight stability. Leakage may occur due to poor airtightness.

The coating thickness of the modified LSR is preferably 50 μm or more and less than 500 μm. When the modular gasket 200 with the modified LSR coating thickness of 50 μm or less is applied to the fuel cell, a thickness difference occurs in the existing BP (bipolar plate) or sub gasket 210, or the tightening pressure of the fuel cell stack increases. As it becomes non-uniform, a part may reach the pressing limit, and a leak may occur. In addition, when the coating thickness of the modified LSR is applied to 500 μm or more, the gas diffusion layer (GDL) in the center of the MEA 100 does not come into contact with the existing BP (bipolar plate) surface, resulting in deterioration of the performance of the fuel cell stack. can be

The modified LSR is preferably prepared by using 1 part by weight or less of silane. When 2 parts by weight or more of the silane used to improve the acid resistance of the modular gasket 200 is used, the basic physical properties of the LSR may be changed and negatively affect the sealing effect, and a more detailed description thereof will be described later. do.

The current collector 300 is formed on the main gasket, and is electrically connected to the anode current collector 310 and the cathode 130 electrode electrically connected to the anode 110 electrode of the MEA 100 having a three-layer structure. A cathode current collector 320 may be included, and since the current collector 300 is the same as the current collector used in the conventional fuel cell, a detailed description thereof will be omitted.

<Experimental Example 1>

a1) Preparation of denatured LSR

After mixing 79 parts by weight of LSR having a hardness of 60 to 20 parts by weight of LSR having a hardness of 10, 1 part by weight of silane containing fluorine was mixed to prepare a modified LSR having a hardness of 50.

b1) Primer treatment on PI film

Before coating the modified LSR prepared by the above method on the PI film, which is the base layer 212, on the PI film having a thickness of 75 μm, a primer for PI is coated using a comma coater to coat/dry the LSR The surface was treated so that the LSR would not come off the PI film.

c1) coating of modified LSR

The modified LSR prepared by the above method was coated/dried to a thickness of 125 μm using a comma coater on a 75 μm thick PI film treated with a primer on the surface to prepare a modular gasket coated with a rubber component. . Here, since the thermosetting resin, which is a constituent of the adhesive layer under the PI Film, may be manufactured by a method of manufacturing a sub-gasket generally used in fuel cells, a detailed description thereof will be omitted.

<Experimental Example 2>

a2) Preparation of denatured LSR

After mixing 79.5 parts by weight of LSR having a hardness of 60 to 20 parts by weight of LSR having a hardness of 10, 0.5 parts by weight of silane containing fluorine was mixed to prepare a modified LSR having a hardness of 50.

b2) Primer treatment on PI film

Before coating the modified LSR prepared by the above method on the PI film, a primer for PI is coated on the PI film with a thickness of 75 μm using a comma coater. The surface was treated so as not to come off.

c2) coating of modified LSR

The modified LSR prepared by the above method was coated/dried to a thickness of 125 μm using a comma coater on a 75 μm thick PI film treated with a primer on the surface to prepare a modular gasket coated with a rubber component. .

<Experimental Example 3>

a3) Preparation of denatured LSR

After mixing 78 parts by weight of LSR having a hardness of 60 to 20 parts by weight of LSR having a hardness of 10, 2 parts by weight of silane containing fluorine was mixed to prepare a modified LSR having a hardness of 50.

b3) Primer treatment on PI film

Before coating the modified LSR prepared by the above method on the PI film, a primer for PI is coated on the PI film with a thickness of 75 μm using a comma coater. The surface was treated so as not to come off.

c3) coating of modified LSR

The modified LSR prepared by the above method was coated/dried to a thickness of 125 μm using a comma coater on a 75 μm thick PI film treated with a primer on the surface to prepare a modular gasket coated with a rubber component. .

<Comparative Example 1>

a4) Preparation of denatured LSR

After mixing 100 parts by weight of LSR having a hardness of 60, 1 part by weight of silane containing fluorine was mixed to prepare a modified LSR having a hardness of 50.

b4) Primer treatment on PI film

Before coating the modified LSR prepared by the above method on the PI film, which is the base layer 212, on the PI film having a thickness of 75 μm, a primer for PI is coated using a comma coater to coat/dry the LSR The surface was treated so that the LSR would not come off the PI film.

c4) coating of modified LSR

The modified LSR prepared by the above method was coated/dried to a thickness of 125 μm using a comma coater on a 75 μm thick PI film treated with a primer on the surface to prepare a modular gasket coated with a rubber component. . Here, since the thermosetting resin, which is a constituent of the adhesive layer under the PI Film, may be manufactured by a method of manufacturing a sub-gasket generally used in fuel cells, a detailed description thereof will be omitted.

<Comparative Example 2>

Instead of LSR, EPDM (Ethylene Propylene Diene Terpolymer) was used to manufacture a modular gasket through PI film and insert injection.

<Evaluation>

A) Measurement of permanent compression set of modular gaskets

Using the compression set measurement cell configured as shown in FIG. 5, the modular gaskets manufactured in Experimental Examples 1 to 3 and Comparative Examples 1 and 2 were punched to a diameter of 25 Φ to produce a sample, and then the thickness Measure and compress the specimen up to 25% by combining a spacer made of SUS material to the outside of the cell, inserting the sample, tightening, and compressing the specimen at 85°C for 100 hours. After taking out the sample, the thickness was measured to calculate the rate of permanent compression set. As a result of the calculation, as summarized in Table 1 below, it can be seen that all of the modular gaskets using the LSR type have very good elasticity, around 5%.

<Table 1>

B) Measurement of low-temperature recovery characteristics of modular gaskets

Modular gaskets prepared in Experimental Examples 1 to 3 and Comparative Examples 1 and 2, respectively, were compared with respect to recovery characteristics of TR-10. As summarized in Table 2 below, most of the specimens using LSR had low temperature recovery characteristics of -40 degrees or less, but the specimen made of EPDM of Comparative Example 2 was high at -21 degrees Celsius, and the elasticity of the gasket in the cryogenic state was low. It has been confirmed that can occur.

<Table 2>

C) Measurement of environmental resistance of modular gaskets

The modular gaskets manufactured in Experimental Examples 1 to 3 and Comparative Examples 1 and 2, respectively, were immersed in a sulfuric acid solution having a pH=2 similar to the environment in which the fuel cell is driven, and then maintained at 85° C. Changes were observed. As a result, as shown in FIG. 6, when 1 part by weight or more of silane containing fluorine was used in Experimental Example 1, acid resistance, which is a disadvantage of LSR, was improved, and a weight change similar to that of EPDM was exhibited.

d) Testing for Hydrogen Gas Leak of Modular Gasket

The modular gaskets manufactured in Examples 1 to 3 and Comparative Examples 1 to 2 were sandwiched between BP (Bipolar Plate) after bonding the modular gasket to the edge of the electrolyte membrane for a gas leak test. ) to supply 1 bar of hydrogen, close the valve, and check how much gas leak occurs per hour through the differential pressure gauge. As a result, as summarized in Table 3 below, it was confirmed that when 2 parts by weight or more of silane used to improve acid resistance was used, the basic physical properties of LSR were changed and negatively affected the sealing effect.

<Table 3>

Based on these results, in order to replace the EPDM gasket, which is commonly used when forming a stack, two types of LSR having different hardness are mixed and 1 part by weight of fluorine-added silane is added. A modular gasket was manufactured by applying it to the PI film, and the modular gasket manufactured in this way has all the properties of permanent compression set, low temperature recovery, acid resistance, and gas barrier properties similar to the previously used EPDM gasket for fuel cell stack. It can be used as a modular gasket that does not require a separate BP gasket when applied to

Hereinafter, physical properties of the main gasket 220 of this embodiment will be additionally described with reference to the accompanying drawings.

7 is a thermogravimetric (TGA) graph of a modified LSR according to an embodiment of the present invention, and FIG. 8 is a graph showing the measurement of environmental resistance of a general LSR,

a) Heat resistance properties of modified LSRs

As described above, modified LSR in which silane containing fluorine is mixed with LSR (Liquid Silicone Rubber) is applied because it must have heat resistance properties that do not decompose even when exposed to high heat for a long time when driving a fuel cell. Previously, TGA (Thermogravimetric Analysis) was used to determine the temperature the material could withstand. As shown in the graph shown in FIG. 7 , it was confirmed that the modified LSR of this embodiment had excellent stability when used in a temperature gun of 350 degrees or less.

b) acid resistance of modified LSR

To measure the acid resistance of the modified LSR of this example, the environmental resistance evaluation was performed using the ASTM D471 method, and the acid resistance measurement formula is as follows.

A=W ₀ -W ₁ /W ₀

Here, A means the weight change rate (%), W ₀ means the original weight of the specimen, and W ₁ means the weight after the test. The unmixed general LSR showed continuous weight reduction as shown in FIG. 8. In this example, silane containing fluorine was mixed with LSR having a high crosslinking density to improve acid resistance to LSR. .

The gas barrier property of the modified LSR of this embodiment is preferably 0.1 kpa/min or less. After the cell of the stack is fastened, the hydrogen gas is flowed into the stack at a pressure of 1 bara, the valve is closed, and when the differential pressure of the hydrogen gas inside the stack is 0.1 kpa or more for 1 minute, it is judged that a leak is in progress. did.

c) Permanent compression set of modified LSR

The compression set (ASTM D395, 25% deflection) of the modified LSR of this embodiment is preferably within 5% when compressed to 25% at a temperature of 85 degrees and maintained for 100 hours. Permanent compression set reduction is calculated using the following formula.

C=(t ₀ -t ₂ )/(t ₀ -t ₁ )X100

Here, C means compression set, t ₀ means the original thickness of the specimen, t ₁ is the thickness of the spacer (a material that is 25% thinner than the specimen and has no thickness change), t ₂ is the compression cell ( It means the thickness of the specimen after it is removed from the cell).

In the case of a gasket for a hydrogen fuel cell vehicle stack, after it is tightened, it is subjected to stress for a long time under a constant compressive load. Accordingly, the degree of elasticity representing the repulsive force against compression is one of the most important evaluation items. As a test that can simulate the elasticity of a gasket, the compression set is the most used. Assuming a vehicle life of 10 years, the stack gasket must maintain sufficient elasticity in a compressed state for 87,000 hours. The lower the pitch, the better.

d) Low-temperature recovery characteristics of modified LSR

It is preferable that the low temperature recovery characteristics (ASTM D1329, TR-10) of the modified LSR of this embodiment have a value of -40°C or less. In general, rubber exhibits elasticity above room temperature, but gradually reads viscoelasticity as it becomes low temperature, and eventually loses its original elasticity completely below a certain temperature. Since the fuel cell vehicle stack is used in a cryogenic region in addition to the high-temperature operation conditions described above, low-temperature recovery characteristics must be considered. EPDM and Fluoro Elastomer, which are generally widely used, have poor low-temperature recovery properties, so they can be mixed to compensate for the above disadvantages, but LSR has recovery properties even at cryogenic temperatures of -50 degrees or less. It can be advantageous in application.

9 is a flowchart illustrating a manufacturing sequence of a modular gasket for a fuel cell according to another embodiment of the present invention.

Referring to FIG. 9 , the method (S1000) of manufacturing a modular gasket for a fuel cell according to another embodiment of the present invention includes a modified LSR manufacturing step (S100), a primer coating treatment step (S200), and a main gasket forming step. (S300) and a sub-gasket hardened layer forming step (S400).

In the modified LSR manufacturing step ( S100 ), the modified LSR may be manufactured by mixing silane containing fluorine with LSR (Liquid Silicone Rubber). Here, it is preferable that the modified LSR is manufactured to have a hardness of 30 to 70 (ASTM D2240, Shore A hardness) by mixing a single LSR or two or more LSRs having different hardnesses.

In the primer coating treatment step S200 , a primer coating treatment may be performed on the surface of the base layer 212 including a polyimide (PI) or polyethylene naphthalate (PEN) film.

Here, the modified LSR (Liquid Silicone Rubber) is coated on the base layer 212 and dried. Since the properties between the base layer 212 and the silicone rubber layer formed by the modified LSR are different, the interface is easily detached accordingly. can happen In this embodiment, in order to improve this desorption phenomenon, the surface of the base layer 212 is modified through a primer coating treatment on the base layer 212 before forming (coating) the modified LSR, so that the modified LSR is coated / Even when it dries, you can keep it from falling off.

In the main gasket forming step ( S300 ), the main gasket 220 may be formed by coating the modified LSR on the primer-coated base layer 212 and curing it.

A typical fuel cell stack consists of hundreds of MEA and BP (bipolar plate), and since airtightness must be maintained through uniform surface contact between parts, it is important to control appropriate hardness. If the hardness of the modified LSR applied on the sub gasket 210 is 70 or more, it is too hard to secure airtight stability. Leakage may occur due to poor airtightness.

In addition, it is preferable that the coating thickness of the modified LSR is 50 μm or more and less than 500 μm. When the modular gasket 200 with the modified LSR coating thickness of 50 μm or less is applied to the fuel cell, a thickness difference occurs in the existing BP (bipolar plate) or sub gasket 210, or the tightening pressure of the fuel cell stack increases. As it becomes non-uniform, a part may reach the pressing limit, and a leak may occur. In addition, when the coating thickness of the modified LSR is applied to 500 μm or more, the gas diffusion layer (GDL) in the center of the MEA 100 does not come into contact with the existing BP (bipolar plate) surface, resulting in deterioration of the performance of the fuel cell stack. can be

In addition, it is preferable that the modified LSR is manufactured by using 1 part by weight or less of silane. When 2 parts by weight or more of the silane used to improve the acid resistance of the modular gasket 200 is used, the basic physical properties of the LSR may be changed, which may negatively affect the sealing effect.

In the sub-gasket hardened layer forming step (S400), an adhesive layer including a thermosetting resin may be formed on the lower surface of the base layer 212 to form a hardened layer of the sub-gasket 210 together with the base layer 212 .

The thickness of the adhesive layer 211 constituting the sub gasket 210 is preferably 5 μm or more and 100 μm or less, and more preferably 10 μm to 50 μm. When the thickness of the composition of the adhesive layer 211 is 5 μm or less, sealing may not be performed normally between the electrolyte membrane and the base layer 212 and leakage may occur, and when the thickness is 50 μm or more, the electrolyte membrane In the process of adhering the base layer 212 to the adhesive composition, a problem in which the adhesive composition leaks out may occur.

The base layer 212 constituting the sub-gasket 210 may generally be a PET film, but in this embodiment, a PI (Polyimide) or PEN (Polyethylene Naphthalate) film having excellent mechanical and chemical properties is preferably applied. As will be described later, the modified LSR (Liquid Silicone Rubber) is coated on the base layer 212 to dry it. phenomena can occur. In this embodiment, in order to improve this desorption phenomenon, the surface on the base layer 212 is modified before the formation (coating) of the modified LSR so that the modified LSR does not fall off even if it is coated/dried, a more detailed description thereof will be described later. do.

The thickness of the base layer 212 is preferably 10 to 100 μm, more preferably 10 μm or more and 70 μm or less. When a film of 10 μm or less is used to form the base layer 212, the gas diffusion layer (GDL) is compressed when the fuel cell is fastened, and fuel supply is not provided, so there is a problem that the overall performance of the battery is lowered. , when a film of 70 μm or more is used, the gas diffusion layer (GDL) is present in a floating state between the bipolar plates (BP), and the resistance with the current collector 300 increases, thereby deteriorating the performance of the battery.

What has been described above is only one embodiment for carrying out the manufacturing method of the modular gasket of the fuel cell, the membrane electrode assembly having the modular gasket, and the modular gasket according to the present invention, and the present invention is based on the above embodiment. It is not limited, and as claimed in the claims below, the technical spirit of the present invention is to the extent that various modifications can be made by anyone with ordinary knowledge in the field to which the invention pertains without departing from the gist of the present invention. will say there is

1000: membrane electrode assembly of fuel cell
100: 3layer MEA
110: anode
120: membrane
130: cathode
200: modular gasket
210: sub gasket
211: adhesive layer
212: base layer
220: main gasket
300: current collector
310: anode current collector
320: cathode current collector
S1000: Manufacturing method of modular gasket of fuel cell
S100: modified LSR manufacturing step
S200: primer coating treatment step
S300: Main gasket forming stage
S400: Sub-gasket hardened layer forming step

Claims (20)

sub-gaskets formed on both sides of a three-layer MEA (Membrane Electrode Assembly) in which an anode, a membrane, and a cathode are stacked; and
Modular LSR in which silane containing fluorine is mixed with LSR (Liquid Silicone Rubber) includes a main gasket formed by coating and curing each on the sub gaskets. gasket.
According to claim 1,
The modified LSR is a single LSR or a mixture of two or more LSRs having different hardnesses to have a hardness of 30 to 70 (ASTM D2240, Shore A hardness).
According to claim 1,
The modified LSR is a modular gasket for a fuel cell, characterized in that the silane is used in an amount of 1 part by weight or less.
According to claim 1,
Each thickness of the main gasket is a modular gasket for a fuel cell, characterized in that 50㎛ or more and less than 500㎛.
According to claim 1,
The sub gasket is
an adhesive layer formed on the MEA and including a thermosetting resin; and
and a base layer formed on the adhesive layer and including a polyimide (PI) or polyethylene naphthalate (PEN) film.
6. The method of claim 5,
The thickness of the adhesive layer is a modular gasket of a fuel cell, characterized in that not less than 5㎛ 100㎛.
6. The method of claim 5,
The thickness of the base layer is a modular gasket for a fuel cell, characterized in that 10㎛ or more and 70㎛ or less.
Membrane Electrode Assembly (MEA) having a three-layer structure in which an anode, a membrane, and a cathode are stacked;
Sub-gaskets respectively formed on both sides of the MEA, and a modified LSR in which silane containing fluorine is mixed with LSR (Liquid Silicone Rubber) is coated on the sub-gasket and then cured to form a main gasket. a modular gasket comprising; and
and a current collector respectively formed on the main gasket and electrically connected to the anode and the cathode, respectively.
9. The method of claim 8,
The modified LSR is a single LSR or a mixture of two or more LSRs having different hardnesses to have a hardness of 30 to 70 (ASTM D2240, Shore A hardness).
9. The method of claim 8,
The modified LSR is a membrane electrode assembly of a fuel cell, characterized in that the silane is used in an amount of 1 part by weight or less.
9. The method of claim 8,
A membrane electrode assembly for a fuel cell, characterized in that the thickness of each of the main gaskets is 50 μm or more and less than 500 μm.
9. The method of claim 8,
The sub gasket is
an adhesive layer formed on the MEA and including a thermosetting resin; and
The membrane electrode assembly of a fuel cell, characterized in that it is formed on the adhesive layer and comprises a base layer comprising a PI (Polyimide) or PEN (Polyethylene Naphthalate) film.
13. The method of claim 12,
The thickness of the adhesive layer is a membrane electrode assembly of a fuel cell, characterized in that not less than 5㎛ 100㎛.
13. The method of claim 12,
The thickness of the base layer is a membrane electrode assembly of a fuel cell, characterized in that 10㎛ or more and 70㎛ or less.
preparing a modified LSR by mixing silane containing fluorine with LSR (Liquid Silicone Rubber);
Primer coating treatment on the surface of the substrate layer including the PI (Polyimide) or PEN (Polyethylene Naphthalate) film;
forming a main gasket by coating and curing the modified LSR on the primer-coated base layer; and
and forming an adhesive layer including a thermosetting resin on a lower surface of the base layer to form a cured layer of the sub gasket together with the base layer.
16. The method of claim 15,
The modified LSR is a method of manufacturing a modular gasket for a fuel cell, characterized in that a single LSR or a mixture of two or more LSRs having different hardnesses are mixed to have a hardness of 30 to 70 (ASTM D2240, Shore A hardness).
16. The method of claim 15,
The modified LSR is a method of manufacturing a modular gasket for a fuel cell, characterized in that the silane is used in an amount of 1 part by weight or less.
16. The method of claim 15,
The main gasket is a method of manufacturing a modular gasket for a fuel cell, characterized in that each is manufactured to a thickness of 50㎛ or more and less than 500㎛.
16. The method of claim 15,
The adhesive layer is a method of manufacturing a modular gasket for a fuel cell, characterized in that each is manufactured to a thickness of 5㎛ or more and 100㎛ or less.
16. The method of claim 15,
The base layer is a method of manufacturing a modular gasket for a fuel cell, characterized in that each is manufactured to a thickness of 10㎛ or more and 70㎛ or less.

Images