KR20150138610A - Fuel cell stack and manufacturing method of the same - Google Patents

Abstract

The present invention relates to a fuel cell stack and a manufacturing method thereof. The fuel cell has an electrolytic layer formed between a gas diffusion layer and an electrode layer (or a catalyst layer) to prevent the corrosion of a carrier due to electrode degradation and induces the electrolytic layer to decompose water before the corrosion of the carrier, thereby preventing the electrode degradation. The present invention includes the processes of: preparing electrolyte material slurry for the electrolytic layer; using the electrolyte material slurry to form the electrolytic layer on the surface of an electrode membrane bonding body or the gas diffusion layer; and bonding the electrode membrane bonding body and the gas diffusion layer while having the electrolytic layer there-between.

Description

[0001] Fuel cell stack and manufacturing method thereof [0002]

The present invention relates to a fuel cell stack and a method of manufacturing the same, and more particularly, to a fuel cell stack for improving the durability of a fuel cell by preventing corrosion of a support of a fuel cell electrode and a method of manufacturing the same.

A fuel cell stack mounted on a fuel cell vehicle refers to a device in which a plurality of fuel cell cells are stacked and generate electricity by reacting hydrogen and oxygen electrochemically to generate water.

An electrode membrane assembly (MEA) is located at the innermost portion of each cell unit structure of the fuel cell stack. The membrane electrode assembly includes a catalyst layer for anode and cathode, ) Are applied.

In addition, a gas diffusion layer (GDL) is disposed on the outer portion of the electrode membrane assembly, that is, the outer portion of the catalyst layer, and a fuel is supplied to the outer portion of the gas diffusion layer, A flow field is formed on the surface of the substrate.

The unit cell of the fuel cell is composed of one electrode membrane assembly, two gas diffusion layers, and two separators, and the fuel cell stack of a desired size can be constructed by laminating several tens to several hundred unit cells .

However, the conventional fuel cell has a problem in that the durability and performance of the fuel cell deteriorate due to corrosion of the carbon carrier due to deterioration of the electrode during operation and dissolution of the catalyst metal.

The main causes are high voltage generation due to starting and stopping of the fuel cell during operation and lack of local hydrogen fuel.

Korean Patent Publication No. 2013-0085327 (2013.07.29) Korean Patent No. 1056439 (Aug. Korean Patent No. 821033 (Apr. 2, 2008)

SUMMARY OF THE INVENTION The present invention has been devised in view of the above-mentioned problems, and it is an object of the present invention to provide a method for manufacturing a semiconductor device, which comprises forming a water electrolytic layer between a gas diffusion layer and an electrode layer (catalyst layer) And a method for manufacturing the fuel cell stack, which can prevent deterioration of electrodes by inducing water decomposition.

Accordingly, the present invention provides a process for producing a slurry for a water electrolytic material for a water electrolytic layer; Forming a water electrolytic layer on the surface of the electrode membrane assembly or the gas diffusion layer using the electrolytic solution slurry; And bonding the electrode membrane junction body and the gas diffusion layer with the electrolytic layer interposed therebetween.

According to an embodiment of the present invention, the electrolytic solution slurry contains a water electrolysis catalyst, and examples of the electrolysis solution include a metal material containing iridium (Ir), a metal material containing ruthenium (Ru), iridium (Ir), an oxide containing ruthenium (Ru), an oxide containing a mixture of iridium (Ir) and ruthenium (Ru), a carbon containing a mixture of iridium (Ir) You can use one.

According to an embodiment of the present invention, the above-mentioned water-electrolytic catalyst may be formed of carbon carrying iridium (Ir) -containing metal, carbon carrying ruthenium (Ru) -containing metal, iridium (Ir) A first oxide containing iridium (Ir), a second oxide containing ruthenium (Ru), a first oxide containing ruthenium (Ru), a second oxide containing ruthenium A second oxide on which a first oxide containing iridium (Ir) is supported, and a second oxide on which a first oxide containing ruthenium (Ru) is supported can be used.

At this time, the supporting ratio of the metal material or the first oxide to the carbon or the second oxide may be 1 to 90%.

According to an embodiment of the present invention, the water electrolytic material slurry is prepared by mixing a water electrolytic solution catalyst with a binder and a solvent. As the binder, a sulfonic acid group, a carboxylic acid group, a phosphoric acid group, a phosphonic acid group, A polymer resin having side chains composed of any one or a mixture of two or more selected can be used. As the solvent, a mixture of alcohol, organic solvent and water can be used.

According to an embodiment of the present invention, in the process of forming the electrolytic layer, the electrolytic solution slurry is applied to the electrode membrane assembly by any one method selected from a brushing method, a spray coating method, a bar coating method and a slot die coating method. Or the surface of the gas diffusion layer.

According to an embodiment of the present invention, the process of bonding the electrode membrane assembly and the gas diffusion layer may include a process of bonding the gas diffusion layer coated with the electrolytic layer to the electrode membrane assembly, To the gas diffusion layer.

According to the embodiment of the present invention, in the process of joining the electrode membrane assembly and the gas diffusion layer, the gas diffusion layer is disposed on both sides of the electrode membrane assembly, and then the mixture is heated at a temperature of 60 to 150 ° C and a pressure of 50 to 200 kgf / And is thermally pressed.

The present invention also provides a fuel cell stack including an MEA / GDL junction fabricated by the above-described method, wherein a water electrolysis layer and a gas diffusion layer are disposed on both sides of the electrode membrane assembly in the center, And an interface is formed between the electrode layer positioned at the outer portion of the electrode membrane assembly and the water electrolysis layer.

According to an embodiment of the present invention, the water electrolytic layer is formed to have a thickness of 2 nm to 2000 nm, and preferably has a thickness of 0.5 to 2.0 μm.

In the present invention, the following effects can be obtained by forming the electrolytic layer between the electrode membrane assembly and the gas diffusion layer to generate the interface between the electrode layer and the electrolytic layer.

1. Prevention of electrode deterioration by water decomposition of the electrolytic solution in the electrolytic layer in contact with the electrode layer prior to the carrier corrosion, thereby enhancing the durability of the fuel cell.

2. In operation of the fuel cell, the reduction of the electrochemical reaction area between hydrogen and oxygen due to moisture is prevented, thereby increasing the operation efficiency and enhancing the performance of the fuel cell.

3. When the electrolytic solution is mixed with the catalytic material and the electrolytic solution is applied to the electrode layer, excellent performance equal to or better than that of the electrolytic solution can be obtained.

1 is a schematic view showing a fuel cell stack according to an embodiment of the present invention;
2 is a view for explaining a slurry production process for a water electrolysis layer in a method of manufacturing a fuel cell stack according to an embodiment of the present invention;
3 is a view illustrating an example of a process of applying a slurry for a water electrolysis layer in a method of manufacturing a fuel cell stack according to an embodiment of the present invention.
4 is a view illustrating a bonding process between a gas diffusion layer coated with a water electrolytic layer and an electrode membrane assembly in a method of manufacturing a fuel cell stack according to an embodiment of the present invention;
5 is a view showing an evaluation result of the fuel cell stack according to the embodiment of the present invention

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention.

1, the fuel cell stack manufactured in accordance with the present invention has an electrode membrane assembly 10 located on the innermost side and an outer portion of the electrode membrane assembly 10, that is, the outside of the electrode layer (catalyst layer) 12 And the gas diffusion layer 30 is located at the outer portion of the water electrolytic layer 20. [

That is, the fuel cell stack according to the present invention has a structure in which a water electrolysis layer 20 and a gas diffusion layer 30 are stacked on the left and right sides of the electrode membrane assembly 10 at the center.

As is well known, the electrode membrane assembly 10 is configured such that an electrode layer 11 for an anode and a cathode is coated on both sides of the polymer electrolyte membrane 11, And a separation plate 40 on which an electrode flow path, that is, a flow field, is formed to discharge water generated by the reaction.

In FIG. 1, the anode and cathode flow path regions schematically show the position of the separator plate 40 stacked on the outside of the gas diffusion layer 30.

This fuel cell stack is manufactured by preparing the electrode membrane assembly 10 and the gas diffusion layer 30, preparing a slurry for a water electrolytic material 20 for the electrolytic layer 20, A process of forming a water electrolytic layer 20 on the surface of the gas diffusion layer 10 or the gas diffusion layer 30 and a process of bonding the electrode membrane assembly 10 and the gas diffusion layer 30 with the water electrolytic layer 20 interposed therebetween ≪ / RTI >

The water electrolytic material slurry is a mixture of a water electrolytic solution catalyst, a binder and a solvent at a predetermined ratio.

Examples of the electrolytic solution include an Ir metal, a Ru metal, an Ir oxide, a Ru oxide, a Ru metal, a Ru oxide, A metal material or an oxide (first oxide) containing iridium (Ir) or ruthenium (Ru) can be used singly, and the metal material or the first oxide can be carbon (C) or a second oxide (TiO2, SiO2, Al2O3, etc.) may be used. At this time, the supporting ratio of the metal material or the first oxide may be 1 to 90%.

In addition, oxides containing a mixture of iridium (Ir) and ruthenium (Ru) may be used as the electrolytic solution catalyst. For example, IrRu-supported carbon (IrRu / C) and IrRu-containing IrRu oxide may be used.

The binder is a polymer resin having hydrogen ion conductivity. For example, the binder may be a polymer resin having at least one selected from the group consisting of a sulfonic acid group, a carboxylic acid group, a phosphoric acid group, a phosphonic acid group, .

In other words, the binder may be a polymer resin having side chains composed of any one or a mixture of two or more selected from a sulfonic acid group, a carboxylic acid group, a phosphoric acid group, a phosphonic acid group, and derivatives thereof.

Such a binder can be used in the form of a single substance or a mixture, and a mixture of alcohol, organic solvent and water is used as the solvent.

The water electrolytic material slurry comprising the above-mentioned water electrolytic catalyst, binder and solvent is prepared by mixing a small amount of deionized water with a water electrolytic catalyst and then adding a binder and mixing, stirring, Mixing, mixing, ultrasonic, and the like may be repeatedly mixed and mixed several times over a certain period of time by mixing with a solvent through an ultrasonic or the like.

Referring to FIG. 2, first, a predetermined amount of water electrolysis catalyst is mixed with a predetermined amount of deionized water, and a predetermined amount of binder is added to a water electrolysis catalyst mixed with deionized water. Then, mixing, stirring, ), And ultrasonic. Then, the mixture of the electrolytic solution catalyst and the binder is put into a certain amount of solvent, and mixed by mixing, stirling, and ultrasonic waves several times over a certain period of time. Thereby producing an electrolytic material slurry.

For example, 2.0 grams of a commercially available or synthetic hydrotreating catalyst is used, 2.5 ml of deionized water is used, and the binder is a commercially available ionomer (Hyflon) (solid content 24.5 %) And a mixture of 0.6 g of EG (Ethylene Glycol), 8.5 g of butanol and 6.0 g of IPA (Isopropanol Alcohol) was used as the solvent. The water electrolytic catalyst and the binder were stirred for about 30 minutes When the solvent is mixed with the mixture of the electrolytic solution catalyst and the binder, the mixture is repeatedly mixed for about 30 minutes for 5 times.

The thus prepared water electrolytic material slurry is applied to one surface of the electrode layer of the electrode membrane assembly or the gas diffusion layer or the microporous layer of the gas diffusion layer to form a water electrolytic layer.

Although not shown in the drawings, the microporous layer may be disposed on one surface of the gas diffusion layer to be bonded to the electrode membrane assembly, and the water electrolytic material slurry may be applied on the microporous layer formed on one surface of the gas diffusion layer.

The microporous layer has a plurality of micropores formed therein. The microporous layer is usually disposed on one surface of the gas diffusion layer to reduce the contact resistance of the fuel cell. In addition, water condensed in the catalyst layer is dispersed in micropores It is also used to prevent the flooding phenomenon by transferring quickly from the micro pore to the macro-pore of the gas diffusion layer.

That is, the electrolytic layer may be formed of a metal slurry containing iridium (Ir, Iridium) or ruthenium (Ru) or a metal (iridium, ruthenium, etc.) Is coated on one surface of a gas diffusion layer or the like with a predetermined thickness.

At this time, the water-receiving material slurry can be sprayed and applied on one surface of a gas diffusion layer or the like by various methods such as a brushing method, a spray coating method, a bar coating method (casting method), a slot die coating method, A conventional gas diffusion layer used in a fuel cell stack is used.

FIG. 3 schematically shows a process of coating the electrolytic layer 20 on one side of the gas diffusion layer 30 using a spray coating method.

The water electrolytic layer 20 is formed by coating with a thickness of 2 nm to 2000 nm. If the water electrolytic layer 20 is coated to a thickness smaller than the thickness of the water electrolytic layer 20, the content of iridium or carbon in the water electrolytic layer 20 is too small, If the coating thickness is thicker than this, the operation efficiency is reduced due to the increase in the volume of the fuel cell stack.

Since the water electrolytic solution function is not increased in proportion to the content of iridium or carbon in the water electrolytic layer 20, when the water electrolytic layer 20 is coated with an excessive thickness, the manufacturing cost is increased.

Preferably, the thickness of the water electrolytic layer 20 is 0.5 mu m to 2.0 mu m.

4 schematically shows a step of bonding the gas diffusion layer 30 on which the water electrolytic layer 20 is formed and the electrode membrane assembly 10 by a thermocompression bonding method.

The process of bonding the electrode membrane assembly 10 and the gas diffusion layer 30 with the water electrolytic layer 20 interposed therebetween may be performed as shown in Figure 4 by forming the gas diffusion layer 30 coated with the water electrolytic layer 20, Or may be a process of bonding the electrode assembly 10 to the gas diffusion layer 30 or bonding the electrode membrane assembly 10 coated with the electrolytic layer 20 to the gas diffusion layer 30.

As a bonding method of the electrode membrane junction body 10 and the gas diffusion layer 30, a hot pressing method using a heating press or the like may be adopted. Alternatively, It is also possible.

As described above, the electrolytic solution slurry is applied to one surface of the electrode layer 12 of the electrode membrane assembly 10 or the microporous layer (not shown) of the gas diffusion layer 30 or the gas diffusion layer 30, Layer 20 is formed.

When the water-receiving material slurry is coated on the gas diffusion layer 30 (or the microporous layer of the gas diffusion layer) or coated on the electrode layer 12 of the electrode membrane assembly 10, the electrode layer 12 ) And the gas diffusion layer 30 (or the microporous layer of the gas diffusion layer), the surface-coated water-electrolytic material slurry is subjected to fuel cell driving, SU (Start Up), SD Dowm), fuel shortage, and the like, the water electrolysis function is performed at the interface.

However, when the electrolytic solution slurry is coated on the electrode layer 12 of the electrode membrane assembly 10 as a post-treatment process, the expansion and contraction of the electrode membrane assembly 10 must be taken into account. Therefore, the gas diffusion layer 30 It is preferable to coat the slurry of the electrolytic solution material as a post-treatment process on the microporous layer of the diffusion layer because the process convenience is higher.

That is, it is easier in the process to form the water-receiving layer 20 on the gas diffusion layer 30 (or the microporous layer of the gas diffusion layer), which does not need to take account of the expansion and contraction equilibrium separately in coating the water electrolytic material slurry .

In addition, when the surface of the gas diffusion layer 30 (or the microporous layer of the gas diffusion layer) is coated with the electrolytic material slurry, the gas diffusion layer 30 may be coated with a post-treatment process, And the problem caused by shrinkage need not be considered.

Hereinafter, examples and comparative examples are provided for evaluating the physical properties of the MEA / GDL conjugate prepared according to the present invention, but the present invention is not limited thereto.

FIG. 5 is a graph showing the results of evaluation of physical properties of the MEA / GDL conjugate prepared according to the present invention, and a schematic cross-sectional structure of the MEA / GDL conjugate prepared according to the following examples and comparative examples.

Example  : The gas diffusion layer  On the surface Water electrolytic layer  formation

The slurry containing the electrolytic solution material (slurry containing the iridium-impregnated carbon) was uniformly coated on the surface of the ordinary gas diffusion layer by a spray coating method, and then the coated gas diffusion layer was coated with 70 Lt; 0 > C for 30 minutes to form a water electrolytic layer. Thereafter, a gas diffusion layer having a water electrolytic layer formed on both side surfaces of the electrode membrane assembly was hot-pressed at a temperature of 60 to 150 DEG C and a pressure of 50 to 200 kgf / cm < 2 > (5-layer) MEA / GDL conjugate was prepared.

Comparative Example  : Containing a hydrotreating catalyst Electrode layer  formation

An electrode slurry was prepared using a mixture of the same amount of the electrolytic solution of the electrolytic solution (iridium-impregnated carbon) used in the above example and platinum or carbon catalyst, and the electrode slurry was coated on both sides of the polymer electrolyte membrane coating) to prepare an electrode membrane assembly. Thereafter, a gas diffusion layer was disposed on both sides of the electrode membrane assembly, hot-pressed at a temperature of 60 to 150 캜 and a pressure of 50 to 200 kgf / cm 2 using a hot press machine to form a 5-layer structure MEA / GDL conjugates were prepared.

Property evaluation

Air and hydrogen were injected into the MEA / GDL junction fabricated according to the above Examples and Comparative Examples in a humidified environment of 50%, and the current density-voltage change was measured at 65 ° C. The evaluation results are shown in FIG. 5 .

As shown in FIG. 5, it can be seen that the MEA / GDL conjugate according to the embodiment has better performance in the low current region than the MEA / GDL conjugate according to the comparative example.

When a water electrolytic catalyst (or a water electrolytic substance) is added to the electrode, iridium (Ir) is much lower in ORR (oxygen reduction reaction) and HOR (hydrogen reduction reaction) than platinum (Pt). Therefore, when the fuel (hydrogen, oxygen) is supplied, iridium is carried on the active site (the position where the electrochemical reaction of the fuel takes place) of the electrode made of only platinum-carrying carbon The performance of the fuel cell is deteriorated because the active site of the electrode made of carbon and platinum supported carbon (electrode containing a water electrolysis catalyst) is relatively small. The reason why the active site is small is that the iridium-loaded carbon interferes with the electrochemical reaction of the fuel (hydrogen, oxygen).

In other words, when the surface of the gas diffusion layer is coated with a water electrolytic material (Example), the fuel supplied into the electrode is obstructed in finding the active position on the surface of the platinum-supported carbon (i.e., electrode) Resulting in less performance degradation, and relatively improved performance compared to the comparative example.

Here, the active site refers to a portion having a three-phase interface between carbon, a binder and a catalyst (platinum, iridium), and a portion where an electrochemical reaction of fuel supplied to the electrode occurs.

The performance of the MEA / GDL junction according to the present embodiment is 1-2% lower in the low current region than the MEA / GDL junction according to the comparative example. (See Figure 5 and Table 1), and these values are significant performance differences in the low current region.

Table 1 below shows the performance increase rate of the MEA / GDL conjugate according to the embodiment versus the MEA / GDL conjugate according to the comparative example.

Also, as shown in FIG. 5, it can be seen that the performance of the MEA / GDL junction according to the embodiment increases in the high current region compared with the MEA / GDL junction according to the comparative example.

This is due to the reduced mass transfer resistance in the high current region of the MEA / GDL conjugate according to the embodiment than the MEA / GDL junction according to the comparative example.

The high current region is known to have a large influence by the mass transfer resistance. By coating the surface of the gas diffusion layer with the slurry containing the iridium-carrying carbon-containing electrolytic solution, the pores through which the water is discharged into the gas diffusion layer are ensured between the electrode layer and the gas diffusion layer, The performance of the MEA / GDL conjugate according to the embodiment in the high current region is improved compared to the MEA / GDL conjugate according to the comparative example.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, And are included in the scope of the present invention.

10: electrode membrane junction body
11: electrolyte membrane
12: electrode layer
20: Water electrolytic layer
30: gas diffusion layer
40: separation plate

Claims (14)

Preparing a water electrolytic material slurry for a water electrolytic layer;
Forming a water electrolytic layer on the surface of the electrode membrane assembly or the gas diffusion layer using the electrolytic solution slurry;
Bonding the electrode membrane assembly and the gas diffusion layer with the electrolytic layer interposed therebetween;
Wherein the fuel cell stack includes a plurality of fuel cell stacks.
The method according to claim 1,
The water electrolytic material slurry contains a water electrolytic catalyst, and the electrolytic solution includes a metal material containing iridium (Ir), a metal material containing ruthenium (Ru), an oxide containing iridium (Ir) (Ru), an oxide containing a mixture of iridium (Ir) and ruthenium (Ru), and a carbon carrying a mixture of iridium (Ir) and ruthenium (Ru) A method of manufacturing a fuel cell stack.
The method according to claim 1,
The water electrolytic material slurry contains a water electrolysis catalyst. Examples of the water electrolysis catalyst include carbon on which a metal substance containing iridium (Ir) is supported, carbon on which a metal substance containing ruthenium (Ru) is supported, iridium A second oxide on which a metal material containing ruthenium (Ru) is carried, a second oxide on which a ruthenium (Ru) -containing metal material is supported, a carbon on which a first oxide containing iridium (Ir) A second oxide on which a first oxide containing iridium (Ir) is supported, and a second oxide on which a first oxide containing ruthenium (Ru) is supported is used Wherein the fuel cell stack is a fuel cell stack.
The method of claim 3,
Wherein the supporting ratio of the metal or the first oxide to the carbon or the second oxide is 1 to 90%.
The method according to claim 1,
The water electrolytic material slurry is prepared by mixing a water electrolytic solution catalyst with a binder and a solvent, and the binder may be any one selected from a group consisting of a sulfonic acid group, a carboxylic acid group, a phosphoric acid group, a phosphonic acid group, Wherein a polymer resin having side chains is used.
The method according to claim 1,
Wherein the water electrolytic material slurry is prepared by mixing a water electrolytic solution catalyst, a binder and a solvent, and the solvent is a mixture of alcohol, organic solvent, and water.
The method according to claim 1,
In the process of forming the water electrolytic layer, coating the surface of the electrode membrane assembly or the gas diffusion layer with the electrolytic solution slurry using any one of brushing, spray coating, bar coating and slot die coating Wherein the fuel cell stack comprises a plurality of fuel cells.
The method according to claim 1,
The process of joining the electrode membrane assembly and the gas diffusion layer may include bonding the gas diffusion layer coated with the electrolytic layer to the electrode membrane assembly or bonding the electrode membrane assembly coated with the electrolysis layer to the gas diffusion layer Wherein the fuel cell stack is a fuel cell stack.
The method according to claim 1,
In the process of bonding the electrode membrane junction body and the gas diffusion layer, the gas diffusion layer is disposed on both sides of the electrode membrane junction body, followed by thermocompression bonding at a temperature of 60 to 150 DEG C and a pressure of 50 to 200 kgf / ≪ / RTI >
Wherein an electrolyte layer and a gas diffusion layer are disposed in order on both sides of the electrode membrane junction body in the center, and an interface is formed between an electrode layer positioned at an outer portion of the electrode membrane junction body and the electrolyte layer. Battery stack.
The method of claim 10,
Wherein the water electrolytic layer has a thickness of 2 nm to 2000 nm.
The method of claim 10,
Wherein the water electrolytic layer has a thickness of 0.5 mu m to 2.0 mu m.
The method of claim 10,
Wherein the water electrolytic layer is formed by coating a slurry of a water electrolytic material on a surface of an electrode membrane assembly or a gas diffusion layer, the water electrolytic material slurry containing a water electrolysis catalyst, and the water electrolysis catalyst is a metal containing iridium (Ir) Wherein the fuel cell stack is any one selected from the group consisting of ruthenium (Ru) -containing material, iridium (Ir) -containing oxide, and ruthenium (Ru) -containing oxide.
The method of claim 10,
Wherein the water electrolytic layer is formed by coating a slurry of a water electrolytic material on a surface of an electrode membrane assembly or a gas diffusion layer, the water electrolytic material slurry containing a water electrolysis catalyst, and the water electrolysis catalyst is a metal containing iridium (Ir) A second oxide on which a metal substance containing ruthenium (Ru) is carried, a second oxide on which a metal substance containing ruthenium (Ru) is impregnated, a second oxide on which a ruthenium (Ru) A first oxide-bearing carbon containing ruthenium (Ru), a second oxide containing iridium (Ir), a second oxide containing iridium (Ir) And a second oxide on which a first oxide containing Ru is supported.

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