KR20090042000A - Fuel cell stack having current collector with an elastic structure - Google Patents

Abstract

A fuel cell stack is provided to increase the joint pressure power and to improve performance by comprising an elastic structure and to improve durability by having the appropriately controlled effective area ratio rate. A fuel cell stack comprises a pair of end plates(140) which are arranged to be separated and faced; a current generator which is arranged between a pair of end plat and generates electric current through electro chemical reaction of oxidizer and reaction fuel; and a current collector(130) which is arranged to be adhered closely to the current generator ad collects the current of the current generator.

Description

Fuel cell stack having current collector with an elastic structure

The present invention relates to a fuel cell stack having a current collector. More particularly, the present invention relates to a fuel cell stack having an elastic current collector. It relates to a fuel cell stack having a.

Recently, due to the rapid dissemination of portable electronic devices and wireless communication devices, a lot of interests and researches on the development of a fuel cell for power generation as a portable power supply and a clean energy source.

A fuel cell is a new power generation system that converts energy generated by electrochemical reaction between fuel gas (hydrogen or methanol) and oxidant (oxygen or air) directly into electrical energy.

Such fuel cells are classified into phosphoric acid fuel cells, molten carbonate fuel cells, solid oxide fuel cells, polymer electrolyte fuel cells, or alkaline fuel cells, depending on the type of electrolyte used. Each of these fuel cells operates on essentially the same principles, but differs in the type of fuel used, operating temperature, catalyst and electrolyte.

Among these, a polymer electrolyte membrane fuel cell (PEMFC) is a hydrogen fuel cell that uses hydrogen as a fuel or a direct methanol that supplies liquid methanol to an anode when the fuel cell is subdivided according to the type of fuel. The fuel cell may be classified into a direct memthanol fuel cell (DMFC).

Since the hydrogen fuel cell and the direct methanol fuel cell can be operated at room temperature and can be miniaturized, various fields such as pollution-free electric vehicles, household power generation systems, mobile communication equipment, medical devices, military equipment, space business equipment, portable electronic devices, etc. It can be used as a power source for.

Meanwhile, a monopolar type fuel cell, which is a type of polymer electrolyte fuel cell, is a method of connecting each unit cell in series after arranging a plurality of unit cells side by side in a width direction between a pair of end plates. A fuel cell, in particular, such a stacked fuel cell has the advantage that the system can be thinned by greatly reducing the thickness and volume. In addition, as a monopolar fuel cell, a fuel cell including a polymer electrolyte fuel cell and a direct methanol fuel cell suitable for portable use at low temperature and atmospheric pressure has been studied.

1 is a cross-sectional view showing a unit cell of a monopolar fuel cell stack according to the prior art.

Referring to FIG. 1, the unit cell of the monopolar fuel cell stack includes a membrane electrode assembly (MEA), a membrane electrode assembly protection gasket 20, an anode electrode fuel supply gasket 22, A cathode electrode supply gasket 24, an anode current collector 32, a cathode current collector 34, an anode end plate 42 and a cathode end plate 44 are provided.

The membrane electrode assembly 10 has a structure in which an anode (not shown) and a cathode (not shown) are closely contacted with a polymer electrolyte membrane (not shown) interposed therebetween. In the membrane electrode assembly 10, a reaction fuel and an oxidant react with each other electrochemically to generate a current.

The membrane electrode assembly protective gasket 20 is disposed on the edge of the membrane electrode assembly 10, that is, the edge of the polymer electrolyte membrane, to prevent gas or liquid used as fuel from flowing out through the electrolyte membrane. It serves to protect the electrodes of the assembly 10 from being broken.

The anode current collector 32 is disposed on one surface of the membrane electrode assembly 10, and the cathode current collector 34 is disposed on the other surface of the membrane electrode assembly 10, so that the membrane electrode assembly 10 is disposed at the membrane electrode assembly 10. It collects the generated current and delivers it to the external circuit.

The anode fuel supply gasket 22 and the cathode fuel supply gasket 24 are disposed on the edges of the anode current collector 32 and the cathode current collector 34, respectively, to smoothly inject and discharge fuel. A passageway to prevent the fuel from flowing out. In addition, it is preferable that the arrangement position of the fuel supply part gaskets 22 and 24 is appropriately selected within a range not covering the through-holes (not shown) of the current collectors 32 and 34.

The anode end plate 42 and the cathode end plate 44 are disposed on the respective fuel supply gaskets 22 and 24, respectively.

In addition, the fuel cell fastening screw 50 is fastened to penetrate the edge portions of the end plates 42 and 44, thereby completing the formation of the fuel cell stack and increasing the fastening pressure thereof.

FIG. 2 is a diagram illustrating only the membrane electrode assembly 10, the current collector 30, and the end plate 40 in FIG. 1. In this case, the current collector 30 may be the anode current collector 32 or the cathode current collector 34 of FIG. 1, and the end plate 40 may be the anode end plate 42 of FIG. 1. Or a cathode end plate 44.

Referring to FIG. 2, the current collector 30 has a stripe-shaped longitudinal direction cross section and a cross section. That is, the plane of the current collector 30 is completely flat. In the current collector 30 having the flat plane as shown in FIG. 2, there is no factor that increases the fastening pressure.

Therefore, the monopolar fuel cell stack having the above configuration can generally increase its fastening pressure by increasing the thickness and width of the end plate 40 and the size and number of the screws 50. When the fastening pressure is small, electrical resistance may be generated between the membrane electrode assembly 10 and the current collector 30, and there may be a loss of electricity, and a problem may occur in which liquid and gas are leaked to the outside.

In addition, such a monopolar polymer electrolyte fuel cell is limited in volume because it is used in a portable manner. Therefore, the key is to be able to achieve maximum performance with sufficient fastening pressure while having a small volume.

As a method for increasing the clamping pressure of a fuel cell, there are conventionally a method of widening the pressure area by increasing the size or number of screws and a method of widening the pressure area by increasing the thickness of the end plate. However, these methods are not suitable for adoption because of the disadvantage of increasing their volume when using a fuel cell in a portable manner.

On the other hand, as a way to reduce the overall volume of the fuel cell by reducing the width of the edge, there is also a technique for introducing an adhesive type fastening method (Korea Patent Publication No. 2006-0023501). However, this type of bonding method has a problem in that it does not provide sufficient surface pressure (ie, clamping pressure) to the membrane electrode assembly.

An object of the present invention is to provide a fuel cell stack in which a fastening pressure is increased by improving the performance by providing a current collector having an elastic structure.

It is another object of the present invention to provide a fuel cell stack in which durability can be improved by providing a current collector having an appropriately adjusted effective area ratio.

The present invention to solve the above problems,

A pair of end plates spaced apart from each other;

At least one current generator disposed between the pair of end plates to generate a current by an electrochemical reaction between a reaction fuel and an oxidant; And at least one current collector disposed in close contact with the current generator to collect current from the current generator,

The current collector provides a fuel cell stack having an elastic structure.

According to one embodiment of the invention, the current collector is bent, the convex portion is disposed opposite the current generating portion.

According to another embodiment of the present invention, one end surface in the thickness direction of the current collector is arcuate, cap, or wave.

According to another embodiment of the present invention, one end surface of the current collector in the thickness direction has a step, and the protrusion is disposed to face the current generator.

According to another embodiment of the present invention, the effective area ratio of the current generating unit is 20 to 50%.

According to another embodiment of the invention, the material of the current collector is an electrochemically stable metal or metal alloy within the potential range of 0.1 to 1V, preferably 0 to 1V.

According to another embodiment of the invention, the thickness of the current collector is 0.1 to 2mm.

According to another embodiment of the present invention, the current generator includes a membrane electrode assembly (MEA) including a polymer electrolyte membrane and an anode and a cathode disposed in close contact with both surfaces thereof.

According to another embodiment of the present invention, the current generators are arranged side by side in the width direction of the end plate and between them are electrically connected in series.

According to another embodiment of the present invention, a bipolar plate is further disposed between the current generator and the current collector, the current collector is disposed in close contact with the bipolar plate to collect the current of the current generator.

According to the present invention, by providing a current collector having an elastic structure, a fuel cell stack can be provided in which a fastening pressure is increased and performance can be improved.

In addition, according to the present invention, a fuel cell stack capable of improving durability by providing a current collector having an appropriately adjusted effective area ratio can be provided.

Next, a fuel cell stack according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

3 is a view illustrating a unit cell of a monopolar fuel cell stack according to an embodiment of the present invention in correspondence with FIG. 2.

Referring to FIG. 3, a fuel cell stack according to an embodiment of the present invention includes a membrane electrode assembly 100, a current collector 130, and an end plate 140.

In the present embodiment, a plurality of membrane electrode assemblies 100 and a current collector 130 having a large area to cover all of them or the membrane electrode assembly 100 on the end plate 140 having a large area. A plurality of current collectors 130 covering each of them are disposed side by side in the width direction of the end plate 140. In addition, the membrane electrode assembly 100, the current collector 130, and the end plate 140 are fastened by the fastening screw 150. The fuel cell stack having the arrangement as described above is called a monopolar fuel cell stack.

The membrane electrode assembly 100 is a type of current generator that generates a current by an electrochemical reaction between a reaction fuel and an oxidant. The membrane electrode assembly 100 is a polymer electrolyte membrane (not shown) and an oxide electrode (not shown) closely disposed on both sides thereof. And a cathode (not shown). Instead of the membrane electrode assembly 100, various other types of current generators may be employed.

The current collector 130 has an elastic structure. Specifically, in the present embodiment, the current collector 130 has a curved shape, as shown in FIG. 3, one end surface in the thickness direction is curved to have an arc shape, and the convex portion C is a membrane electrode assembly. It is arranged to face 100.

In addition, the material of the current collector 130 is a metal or metal alloy having elasticity, and the metal or metal alloy is platinum, titanium, electrochemically stable within the potential range of 0.1 to 1V, preferably 0 to 1V. Gold, nickel, alloys thereof, and the like are preferable. That is, since the reaction fuel (hydrogen) or oxidant (oxygen) is oxidized or reduced within the potential range of 0 to 1V, the current collector 13 must be electrochemically stable within the potential range.

In addition, in this embodiment, the thickness of the current collector 13 is preferably 0.1 to 2mm.

In the fuel cell stack having the above structure, when the stack is fastened, the fastening screw 150 tightens the fastening screw 150 to push the end plate 140 toward the membrane electrode assembly 100 and the end plate 140. Again pushes the edge portion of the current collector 130 in the same direction. If the tightening screw 150 is further tightened, the pressure applied to the edge portion of the current collector 130 increases, and this pressure is ultimately transmitted to the convex portion C of the current collector 130, thereby providing the convex portion. (C) is gradually straightened by the elastic force. As such, the convex portion C of the current collector 130 is straightened, and a considerable pressure is applied to the surface of the membrane electrode assembly 100 which contacts the convex portion C. As a result, the fastening pressure of the fuel cell stack is increased. This increases, resulting in a sufficiently low electrical resistance in the stack, resulting in a desired power density. By fabricating the current collector 130 having an elastic structure as described above, the desired clamping pressure can be obtained without increasing the thickness of the end plate 140, and the performance can be improved, and the fuel cell stack can be thinned.

4 is a cross-sectional view illustrating the current collector of FIG. 3 and other various types of current collectors that may replace the current collector.

Fig. 4 (a) shows a current collector having one end surface in an arcuate direction in thickness, caps (b) and (c), and caps (e). The current collector of FIG. 4 (a) has an advantage of being able to bend and use a current collector having a flat plane without any special processing technique.

The current collectors of FIGS. 4 (b), 4 (c) and 4 (e) have a merit in that the change in the bending angle is not large compared to the current collector of FIG. In each of these cases, the thickness t _F of the flat portion F is preferably 0.1 to 2 mm, and the thickness t _C of the convex portion C is preferably 0.01 to 1 mm. When the thicknesses t _{F and} t _C deviate from the above ranges, it is not preferable because it is difficult to obtain a desired clamping pressure or a thin film cannot be achieved. Further, when the thickness (t _C) difference between the flat portion (F) The thickness (t _F) and the convex portion (C) of causing a departure from the value range that can be derived from the above-described range because the perfect airtight during stack fastening not holding the reaction fuel Is not preferable because it is easy to leak.

4 (d) shows a current collector having one step in the thickness direction end surface. In this case, the protrusion P of the current collector is disposed to face the membrane electrode assembly. In this case, the current collector preferably has a thickness t _F of the flat portion F of 0.1 to 2 mm and a thickness t _P of the protrusion P to be 0.01 to 1 mm. When the thicknesses t _{F and} t _P deviate from the above ranges, it is not preferable because sufficient fastening pressure is difficult to obtain or thinning cannot be achieved. Further, when the thickness (t _P) difference between the flat portion (F) The thickness (t _F) with the projection (P) for causing a departure from the numerical range which can be derived from the scope stack tightening when complete confidentiality is not being maintained the reaction of fuel It is not preferable because it is easy to leak.

5 is a plan view illustrating a case where through holes of various sizes and shapes are formed in the current collector of FIG. 3.

Referring to FIG. 5, a current collector 130-1 having a circular through hole h1 is formed in FIG. 5A, and a small square through hole h2 is formed in (b). The current collectors 130-2 and (c) which show the current collector 130-3 in which the large square through-hole h3 is formed are shown, respectively. Here, the shape of the through holes h1, h2, and h3 is not important, and the area of the through holes h1, h2, and h3 has an important meaning in terms of efficiency for supplying fuel such as reaction fuel.

Efficient fuel supply of the current collectors 130-1, 130-2 and 130-3 according to the total area of the through holes h1, h2 and h3 in FIGS. 5A, 5B and 5C The area ratio of the passage (hereinafter referred to as the effective area ratio of the current generating unit) may vary.

The effective area ratio can be obtained by Equation 1 below.

[Equation 1]

Effective area ratio (%) of current generating part = total area of through-hole formed in current collector /

Total area of current generating part X 100

On the other hand, the current collector has a substantial current collecting area in contact with the current generating unit and an area of the fuel supply passage capable of supplying fuel (ie, an effective area).

In order to ensure efficient fuel supply and durability of the fuel cell stack, it is necessary to have an optimum effective area ratio and a current collector area ratio.

The relationship between the effective area ratio and the current collector area ratio may be expressed by Equation 2 below.

[Equation 2]

Current area ratio (%) = 100-effective area ratio

In the present embodiment, the current collector plays the following three roles at the same time. That is, first, the role of the current collector to collect current, and second, through the shape deformation of the current collector, when tightening the stack, the clamping pressure is increased to increase the current generator (ie, membrane electrode assembly) and the current collector. The role of increasing the performance of the fuel cell stack by minimizing the electrical resistance generated during contact between the third, and third, to ensure the durability of the fuel cell stack through efficient fuel supply.

The fuel cell stack of the present invention can be variously applied to a hydrogen fuel cell (PEMFC), a direct methanol fuel cell (DMFC), or a phosphate fuel cell (PAFC), and in particular, a room temperature employing a hydrogen fuel cell and a direct methanol fuel cell. It can be applied more advantageously to the operating fuel cell.

In addition, the embodiment has been described using only a monopolar type as a fuel cell stack, but the present invention is not limited thereto, and the technical features of the present invention may be equally applied to a bipolar fuel cell stack. Although not shown here, the bipolar fuel cell stack further includes a bipolar plate disposed between the current generator and the current collector, and the current collector is disposed in close contact with the bipolar plate so as to provide a current in the current generator. To collect.

The present invention will be described in detail with reference to the following Examples. However, the present invention is not limited only to the following examples.

Example

Preparation Example 1 Preparation of Membrane Electrode Assembly (MEA)

A membrane electrode assembly (MEA) was prepared by using a catalyst coated GDL method as follows. That is, Pt content of 0.4mg / cm ² ~ 0.8mg / cm ² by spraying the catalyst slurry containing Pt catalyst and a small amount of Nafion supported on carbon nanotubes on one surface of carbon paper (SGL10BC) The anode and the cathode were respectively prepared by coating to the extent. On one side and the other side of the electrolyte membrane formed of Nafion® polymer electrolyte 115, the anode and the cathode coated with the catalyst layer obtained above were disposed and hot pressed to obtain a membrane electrode assembly.

Example 1 Manufacture of Unit Cell 1 of Fuel Cell Stack

As the end plate, an acrylic resin having a thickness of 0.5 cm and a size of 6 × 6 cm ² was used. In the end plate, a through hole having a diameter of 2.5 mm was formed in order to smoothly inject and discharge fuel. As a current collector, a SUS 316L material having a thickness of 0.5 cm and a size of 6 × 6 cm ² was used. In addition, the current collector, as shown in Fig. 4 (a), one end surface in the thickness direction is formed in an arc shape. As the membrane electrode assembly, a membrane electrode assembly prepared in Preparation Example 1 having a thickness of 800 μm and a size of 3 × 3 cm ² was used.

In the current collector, a plurality of circular through holes, as shown in FIG. 5A, were formed, and the effective area ratio was adjusted to 36%. As the gasket used for the fuel supply unit and the membrane electrode assembly, red glass silicon having a thickness of 350 µm was used. The unit cell 1 was manufactured by stacking the above components as shown in FIG. 3.

Example 2: Fabrication of unit cell 2 of fuel cell stack

The unit cell 2 was manufactured in the same manner as in Example 1 except that the effective area ratio was adjusted to 24%.

Example 3: Production of unit cell 3 of fuel cell stack

In the same manner as in Example 1, except that the effective area ratio was adjusted to 45% by forming a plurality of small square through-holes as shown in (b) of FIG. 5 in the current collector. The battery 3 was produced.

Example 4: Fabrication of unit cell 4 of fuel cell stack

In the same manner as in Example 1, except that the effective area ratio was adjusted to 55% by forming a plurality of small square through-holes as shown in (b) of FIG. 5 in the current collector. The unit cell 4 was prepared.

Example 5: Fabrication of unit cell 5 of fuel cell stack

In the same manner as in Example 1, except that the effective area ratio was adjusted to 72% by forming a plurality of large square through-holes as shown in (c) of FIG. 5 in the current collector. The battery 5 was produced.

Comparative Example 1: Fabrication of unit cell 6 of fuel cell stack

As the current collector, a unit cell 6 was manufactured in the same manner as in Example 1 except that a current collector having stripe-shaped cross sections as shown in FIG. 2 was used.

Evaluation

The performance test and durability test of the unit cells (1) and (6) manufactured in Example 1 and Comparative Example 1 are carried out, and the results of the performance test are shown in FIGS. 6A and 6B, and the fuel persistence test results are shown in FIG. 7. Indicated. In addition, Examples 1 to 5 were subjected to a durability test according to the effective area ratio change, and the results are shown in Table 1 and FIG. 8.

<Performance test>

Performance test conditions were as follows. That is, while supplying fuel to the unit cells 1 and 6 manufactured in Example 1 and Comparative Example 1 at a rate of H ₂ 100cc / min and O ₂ 100cc / min at room temperature, the current density The cell voltage was measured and the results are shown in FIG. 6A.

Referring to FIG. 6A, the degree of the voltage drop according to the increase of the current density was found to be smaller than that of Comparative Example 1 in the case of Example 1, so that the performance of the unit cell 1 of Example 1 was lower than that of Comparative Example 1. It can be confirmed that it is superior to the performance of (6).

6B again shows the power density calculated by the current density and voltage of FIG. 6A.

Referring to FIG. 6B, the degree of power density increase according to the increase of the current density is shown to be greater in the case of Example 1 than in the case of Comparative Example 1, so that the performance of the unit cell 1 of Example 1 is the unit of Comparative Example 1. It can be seen again that the battery 6 is superior to the performance.

The result of the above performance test, in the process of transferring electricity from the membrane electrode assembly to the current collector, in the case of Example 1 is due to the electrical resistance is reduced than in the case of Comparative Example 1 is improved current characteristics .

<Fuel Persistence Test-Fixed Effective Area Ratio>

Fuel persistence test conditions were as follows. That is, first, a small amount of water is supplied to each of the unit cells 1 and 6 manufactured in Example 1 and Comparative Example 1, and then water is supplied by applying a current of 300 mA using a solar cell (or a power supply). After electrolysis, the generated hydrogen and oxygen were collected in volumes of 15 cc and 7.5 cc, respectively. Next, an experiment was performed in which the collected hydrogen and oxygen were supplied to the unit cells 1 and 6 to measure the change in power over time until all of these fuels (hydrogen and oxygen) were consumed. In this case, the voltage of the unit cell 1 (Example 1) was kept constant at 0.65V, and the voltage of the unit cell 6 (comparative example 1) was kept constant at 0.60V. The results are shown in FIG.

Referring to FIG. 7, the power of Example 1 maintained at a voltage of 0.65V was higher than that of Comparative Example 1 maintained at 0.60V, and the power was dropped as a result of operating for about 2 minutes. The phenomenon was found to be less reduced in the case of Example 1 than in the case of Comparative Example 1. That is, the unit cell 6 of Comparative Example 1 showed a result that the electrical output is greatly reduced as the electrical resistance increases.

In this fuel persistence test, the performance of the unit cell 1 of Example 1 was improved by about 41% or more compared to the performance of the unit cell 6 of Comparative Example 1. This result is believed to be due to the improvement in current characteristics by decreasing the electrical resistance in the case of Example 1 in the process of transferring electricity from the membrane electrode assembly to the current collector.

<Durability test-effective area ratio change>

The fuel sustainability test was performed on the unit cells 1 to 5 manufactured in Examples 1 to 5 under the same conditions as the fuel sustainability test conditions. However, after all of the supplied fuel is exhausted, a small amount of water is electrolyzed again, and the fuel obtained by conducting a test for generating electricity by resupplying the fuel thus obtained to each of the unit cells by the predetermined volume is performed. The test was repeated several times. The test repeatable number of times under the precondition that the output power should be maintained at a constant value is measured and shown in Table 1 below. This durability test is to observe the change in durability of the unit cell according to the change of the effective area ratio.

For reference, the results of the above durability test on the unit cell 1 of Example 1 having an effective area ratio of 36% are shown in FIG. 8. Referring to Figure 8, in the case of Example 1 it can be seen that the durability test can be repeated 46 times.

division Example 1 Example 2 Example 3 Example 4 Example 5 Effective Area Ratio,% 36 24 45 55 72 Test repeatable frequency 46 32 34 22 6

In addition, referring to Table 1, when the effective area ratio is 36%, 24%, 45%, 55%, 72%, the number of test repeatable times was 46, 32, 34, 22, and 6 times, respectively. All. In other words, it can be seen that the durability is relatively good when the effective area ratio is less than 50%, and when the effective area ratio is greater than 50%, as the current collector area ratio decreases, the durability becomes worse due to the increase in the actual electrical resistance. It can be seen. Comparing the case of Example 1 having an effective area ratio of 36% with the case of Example 5 having 72%, the case of Example 1 showed an 800% increase in durability compared to the case of Example 5.

Although preferred embodiments of the present invention have been described above with reference to the accompanying drawings, this is merely illustrative, and those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Could be. Therefore, the protection scope of the present invention should be defined by the appended claims.

1 is a cross-sectional view showing a unit cell of a monopolar fuel cell stack according to the prior art.

FIG. 2 is a diagram illustrating only the membrane electrode assembly, the anode current collector, and the anode end plate in FIG. 1.

3 is a view illustrating a unit cell of a monopolar fuel cell stack according to an embodiment of the present invention in correspondence with FIG. 2.

4 is a cross-sectional view illustrating the current collector of FIG. 3 and other various types of current collectors that may replace the current collector.

5 is a plan view illustrating a case where through holes of various sizes and shapes are formed in the current collector of FIG. 3.

6A and 6B are graphs illustrating performance test results of unit cells of Example 1 and Comparative Example 1 in a comparative format.

FIG. 7 is a graph illustrating fuel sustain test results of unit cells of Example 1 and Comparative Example 1 in a comparative format. FIG.

8 is a graph showing the durability test results according to the effective area ratio for the unit cell of Example 1 in a comparative form.

<Explanation of symbols for the main parts of the drawings>

10, 100: membrane electrode assembly 20: membrane electrode assembly protective gasket

22: anode fuel supply gasket 24: cathode fuel supply gasket

30, 130 current collector 32: anode current collector

34: cathode current collector 40, 140: end plate

42: anode end plate 44: cathode end plate

50, 150: fastening screw h1, h2, h3: through hole

Claims (10)

A pair of end plates spaced apart from each other; At least one current generator disposed between the pair of end plates to generate a current by an electrochemical reaction between a reaction fuel and an oxidant; And At least one current collector disposed in close contact with the current generator and configured to collect current in the current generator; The current collector is a fuel cell stack having an elastic structure. The method of claim 1, And the convex portion is disposed so as to face the current generating portion. The method of claim 2, A fuel cell stack, characterized in that one end surface in the thickness direction of the current collector is arcuate, cap, or wave. The method of claim 1, And one end surface in the thickness direction of the current collector has a step, and a protrusion thereof is disposed to face the current generator. The method of claim 1, A fuel cell stack, characterized in that the effective area ratio of the current generating unit is 20 to 50%. The method of claim 1, The material of the current collector is a fuel cell stack, characterized in that the electrochemically stable metal or metal alloy in the potential range of 0 to 1V. The method of claim 1, A fuel cell stack, characterized in that the thickness of the current collector is 0.1 to 2mm. The method of claim 1, The current generator comprises a membrane electrolyte assembly (MEA) comprising a polymer electrolyte membrane and an anode and a cathode disposed in close contact with both surfaces thereof. The method of claim 1, The fuel cell stack, characterized in that the current generator is arranged side by side in the width direction of the end plate and between them are electrically connected in series. The method of claim 1, A bipolar plate is further disposed between the current generator and the current collector, and the current collector is disposed in close contact with the bipolar plate to collect current in the current generator.

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