KR100872639B1 - Stack structure for mechanical reinforcement of fuel cell - Google Patents

Abstract

A stack structure for the reinforcement of mechanical strength for a fuel cell is provided to prevent the resistance increase due to the interface separation of a catalyst layer and a membrane layer in an MEA and the interface separation of MEA and GDL and to the damage of MEA/GDL due to the repeated stress by the drying/wetting of materials. A stack structure for a fuel cell comprises a separator(16), a GDL(110) and an MEA(12), wherein a reinforcement layer(111) is formed on the gas diffusion layer(GDL) to reinforce the GDL and MEA(membrane electrode assembly) in contact with the separator by the anode/cathode pressure difference, and the reinforcement layer is located between the MEA and the GDL. Also the reinforcement layer is located between the MEA and the GDL and the MEA and the separator. Or the reinforcement layer is buried inside the GLD.

Description

Stack structure for mechanical reinforcement of fuel cell

1 is a schematic view showing a structure of a fuel cell stack according to the prior art, showing a pressure difference between an anode / cathode pole,

FIG. 2 is a diagram for explaining the pressure difference between the system inlet and the outlet of FIG. 1;

3A and 3B are diagrams for describing the pressure difference in the flow path of FIG. 1;

4 is a partial excerpt diagram showing a portion stressed and a portion not stressed by the pressure difference in FIG.

FIG. 5 is a view illustrating a site where fatigue damage occurs under stress as in FIG. 4;

FIG. 6 is an image illustrating a result of analyzing that stress concentration is generated at both ends when pressure is applied under both conditions in FIG. 5.

7A and 7B are principal cross-sectional views schematically showing the structure of a fuel cell stack according to the first embodiment of the present invention;

8A and 8B are cross-sectional views of main parts schematically showing the structure of a fuel cell stack according to a second embodiment of the present invention;

9A and 9B are cross-sectional views of main parts schematically showing the structure of a fuel cell stack according to a third embodiment of the present invention;

10A and 10B are cross-sectional views of main parts schematically showing the structure of a fuel cell stack according to a fourth embodiment of the present invention.

11A and 11B are cross-sectional views schematically illustrating a structure of a fuel cell stack according to a fifth embodiment of the present invention.

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

10 electrolyte membrane 11 electrode

12: MEA 13,110,120,130,140,150: GDL

14 Gasket 15 Sub Gasket

16: separating plate 16a: protrusion

111,121,131,141: Reinforcement

The present invention relates to a stack structure for reinforcing the mechanical strength of a fuel cell, and more particularly, by interfacial peeling of a catalyst layer and a membrane layer in a MEA and an interfacial peeling of a MEA and GDL according to an anode / cathode pressure difference and dry / wet conditions. The reinforcement layer is inserted into the contact with the separator to improve the conventional problem that the MEA / GDL is damaged due to increased resistance, repeated pressure difference, and repeated stress caused by dry / wet of the material, resulting in deterioration of the fuel cell. It relates to a stack structure for reinforcing mechanical strength of a fuel cell.

In general, a fuel cell system is a type of power generation system that converts chemical energy of a fuel directly into electrical energy.

The fuel cell system includes a fuel cell stack that generates electric energy largely, a fuel supply system for supplying fuel (hydrogen) to the fuel cell stack, and an air supply for supplying oxygen in the air, which is an oxidant required for an electrochemical reaction, to the fuel cell stack. The system consists of a heat and water management system that removes the reaction heat from the fuel cell stack to the outside of the system and controls the operating temperature of the fuel cell stack.

With such a configuration, the fuel cell system generates electricity by an electrochemical reaction by hydrogen, which is a fuel, and oxygen in the air, and discharges heat and water as reaction byproducts.

The fuel cell stack is a main power supply source of a fuel cell vehicle, and is an apparatus for producing electricity by receiving oxygen in air and hydrogen as fuel. In addition, a fuel cell stack applied to an automobile is composed of about 400 unit cells or more, and each unit cell forms a voltage of about 0V to 1.33V.

The fuel cell stack, which is widely used for automobiles, is a high-density solid polymer electrolyte fuel cell (Proton Exchange Membrane Fuel Cell, PEMFC).

FIG. 1 is a schematic view showing the configuration of a fuel cell stack, which is a 3L MEA having an electrode / catalyst layer 11 having electrochemical reactions on both sides of the membrane centered on an electrolyte membrane 10 through which hydrogen is turned. Membrane Electrode Assembly (12), Gas Diffusion Layer (GDL) 13, which distributes the reactants evenly and deliver the generated electricity, and the tightness and proper clamping pressure of the reactants and cooling water. It is composed of a gasket 14 and a sub-gasket 15 for holding, and a separator plate 16 through which the reactor bodies and the cooling water move.

In the solid polymer electrolyte fuel cell, hydrogen is supplied to an anode (also referred to as a “fuel electrode”), and oxygen (air) is supplied to a cathode (also referred to as a cathode, “air electrode” or “oxygen electrode”).

Hydrogen supplied to the anode is decomposed into hydrogen ions (Proton, H ⁺ ) and electrons (Electron, e-) by the catalyst of the electrode layer formed on both sides of the electrolyte membrane 10, of which hydrogen ions (Proton, H ⁺ ) Only selectively passes through the electrolyte membrane 10, which is a cation exchange membrane, to the cathode, and at the same time, electrons (Electron, e-) are transferred to the cathode through the gas diffusion layer 13 and the separator (16). .

In the cathode, the hydrogen ions supplied through the electrolyte membrane and the electrons transferred through the separator 16 meet with oxygen in the air supplied to the cathode by the air supply to generate water.

At this time, current is generated by the flow of electrons through the external conductor generated due to the movement of hydrogen ions, and heat is incidentally generated in the water generation reaction.

The electrode reaction of the solid polymer electrolyte fuel cell is shown in the following reaction formula.

[Reaction in Fuel Pole] 2H ₂ → 4H + + 4e-

[Reaction at air electrode] O ₂ + 4H ⁺ + 4e- → 2H ₂ O

[Total Reaction] 2H ₂ + O ₂ → 2H ₂ O + Electrical + Thermal

However, the fuel cell system is deteriorated and damaged due to the pressure difference between the anode / cathode pole (FIG. 1), the pressure difference between the system inlet and outlet (FIG. 2), and the pressure difference in the flow path such as hydrogen or oxygen (FIG. 3). This can happen.

In the case where the pressure difference of FIGS. 1 to 3B occurs, the portion pressed by the separator 16 as in the “A” portion of FIG. 4 is not stressed by the anode / cathode pressure difference, but the “B” portion is shown in FIG. 5. As shown in the drawing, fatigue damage may occur at the “C” and “D” sites under stress.

FIG. 6 is a result of analyzing that stress concentration occurs at both ends C and D when pressure is applied under both conditions.

In addition, the electrolyte membrane (membrane) is repeatedly subjected to dry and wet (WET) conditions due to humidification conditions during fuel cell operation and during start / stop, whereby MEA and GDL are repeatedly contracted and stretched at the “D” site. Accordingly, breakage due to fatigue may occur.

In order to overcome this problem, Japanese Patent No. 1984-146319 (Reinforced Separator), Patent Application No. 2002-5756 (Reinforced MEA) and US Patent No. 2003- for the reinforced structure and the filament insertion GDL of the separator or MEA 688666 (composite material GDL; filament insertion) has been proposed.

However, the patented separator or MEA reinforcement technology has a risk of being damaged by peeling and crack propagation of contacts under severe conditions of dry and wet conditions due to dissimilar materials in MEA during manufacture and operation.

In addition, the filament-inserted composite material GDL has a limitation in that it cannot adequately exert a reinforcing effect due to the pressure difference for each part for the damage caused by the pressure difference.

The present invention has been devised in view of the above, and by inserting a reinforcing layer into a contact portion with a separator plate, the interfacial separation between the catalyst layer and the membrane layer in the MEA, the resistance increase due to the interfacial separation between the MEA and the GDL, and the repetitive pressure It is an object of the present invention to provide a stack structure for reinforcing the mechanical strength of a fuel cell, which can improve the performance of the fuel cell by preventing the MEA / GDL from being damaged by repeated stress caused by dry / wet of the car and the material.

The present invention for achieving the above object in the fuel cell stack structure comprising a separator, GDL and MEA,

The reinforcement layer is formed on the gas diffusion layer (GDL) to reinforce the portions of the GDL and the MEA (membrane electrode assembly) which are in contact with the separator by the anode / cathode pressure difference.

In a preferred embodiment, the reinforcement layer is located between the MEA and the GDL.

In a more preferred embodiment, the reinforcing layer is located between the MEA and the GDL, and between the GDL and the separator, respectively.

In addition, the reinforcing layer is characterized in that located between the GDL and the separator.

In addition, the reinforcing layer is characterized in that the buried in the GDL.

In particular, the reinforcing layer is characterized in that the straight reinforcement made of a structure formed parallel to the vertical and horizontal direction.

In addition, the reinforcing layer is characterized in that the linear reinforcement is formed along the flow path of the separation plate.

In addition, the shape of the reinforcing layer is characterized in that made of any one selected from a straight line, a honeycomb, a straight line connected to the top, bottom, left and right, and a curved reinforcement.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

7A to 11B are diagrams illustrating a structure of a fuel cell stack using a reinforcement layer according to a preferred embodiment of the present invention. Here, the same reference numerals as in the above-described drawings indicate the same members having the same function.

In general, the separation plate 16 is formed with flow paths 17 through which hydrogen, oxygen, and coolant can move, and the separation plate 16 has a protrusion having a concave-convex shape in a double-ply structure to form the flow path 17. It consists of the structure in which 16a was formed.

The protrusion 16a formed on the separator 16 presses the GDL 13 and the MEA 12 due to the anode / cathode pressure difference, thereby causing the interface separation between the catalyst layer and the membrane layer in the MEA 12, and the MEA 12. And an increase in resistance due to interfacial peeling of the GDL 13 occur.

Therefore, the present invention has an emphasis on improving the conventional problem and improving the performance of the fuel cell by forming a reinforcing layer in a portion in contact with the protrusion 16a of the separator 16.

The GDLs 110 to 150 serve to evenly distribute the reactants and transfer electricity generated, and are directly in contact with the separator 16 by being located inside the separator.

Here, the reinforcement layer is present in the GDL (110 ~ 150) according to the present invention. The material of the reinforcing layer may be made of a conductive metal, for example, Cu, Al, Fe, and the like, and may be made of a carbon material having rigidity. The materials described above can be applied to all the embodiments described below.

According to the first embodiment of the present invention, as shown in FIGS. 7A and 7B, a reinforcement layer may be positioned between the GDL 110 and the MEA 12, and the reinforcement layer may be a protrusion ( 16a) and a plurality of reinforcement 111 is formed in the vertical and horizontal directions, that is, the bottom of the portion where the GDL 110 is in contact with the structure formed in a checkered shape.

The second embodiment according to the present invention is a reinforcing layer between the MEA 12 and the GDL 120 and between the protrusions 16a of the GDL 120 and the separator 16 as shown in Figs. 8A and 8B. The reinforcement layer may be located at a portion where the protrusion 16a of the separator 16 and the GDL 120 contact with each other, and a plurality of reinforcements 121 at a lower portion thereof in a vertical and horizontal direction, that is, in a checkered pattern. Each consists of a structure.

In the third embodiment of the present invention, as shown in FIGS. 9A and 9B, a reinforcement layer may be inserted into the GDL 130, and the reinforcement layer may be formed by the protrusions 16a of the separator 16. A plurality of reinforcing member 108 is formed in a vertical and horizontal direction, that is, in the form of a checkered pattern under the portion where the GDL 130 is in contact.

In the fourth embodiment of the present invention, as shown in FIGS. 10A and 10B, a reinforcement layer may be positioned between the separator 16 and the GDL 140, and the reinforcement layer may include a plurality of reinforcement materials 141. It has a structure formed in the horizontal direction along the protrusion (16a) formed in the separating plate (16).

In the fifth embodiment of the present invention, as shown in FIGS. 11A and 11B, a reinforcement layer may be located between the separator plate 16 and the GDL 150, and the reinforcement layer is used to reinforce the mechanical strength. 151 has a structure formed in a vertical horizontal direction, that is, checkered pattern.

The shape of the reinforcement layers 110 to 150 is not limited to a straight line, but may be applied to all fuel cell-related flow paths such as a straight line or a curved flow path connected up, down, left, and right, such as a honeycomb structure.

Although the present invention has been illustrated and described with respect to specific preferred embodiments, the invention is not limited to these embodiments, and the invention is claimed in the claims by one of ordinary skill in the art to which the invention pertains. It includes all embodiments of the various forms that can be carried out without departing from the spirit of the invention.

As described above, according to the stack structure for reinforcing the mechanical strength of the fuel cell according to the present invention, by inserting a reinforcing layer for reinforcing the contact portion with the separator plate, the interface between the catalyst layer and the membrane layer in the MEA, MEA and GDL It is possible to improve the performance of the fuel cell by preventing the MEA / GDL from being damaged by increased resistance due to interfacial separation, repeated pressure differences, and repeated stress caused by dry / wet of the material.

Claims (8)

delete In a fuel cell stack structure comprising a separator, GDL and MEA, The reinforcement layer is formed in the gas diffusion layer (GDL) to reinforce the parts of the GDL and the MEA (membrane electrode assembly) which are in contact with the separator by the anode / cathode pressure difference. The reinforcement layer is a stack structure for enhancing the mechanical strength of a fuel cell, characterized in that located between the MEA and GDL. In a fuel cell stack structure comprising a separator, GDL and MEA, The reinforcement layer is formed in the gas diffusion layer (GDL) to reinforce the parts of the GDL and the MEA (membrane electrode assembly) which are in contact with the separator by the anode / cathode pressure difference. The reinforcement layer is a stack structure for strengthening the mechanical strength of the fuel cell, characterized in that located between the MEA and GDL, and the GDL and the separator. In a fuel cell stack structure comprising a separator, GDL and MEA, The reinforcement layer is formed in the gas diffusion layer (GDL) to reinforce the parts of the GDL and the MEA (membrane electrode assembly) which are in contact with the separator by the anode / cathode pressure difference. The reinforcement layer is a stack structure for enhancing the mechanical strength of a fuel cell, characterized in that located between the GDL and the separator. In a fuel cell stack structure comprising a separator, GDL and MEA, The reinforcement layer is formed in the gas diffusion layer (GDL) to reinforce the parts of the GDL and the MEA (membrane electrode assembly) which are in contact with the separator by the anode / cathode pressure difference. The reinforcement layer is a stack structure for strengthening the mechanical strength of the fuel cell, characterized in that embedded in the GDL. In a fuel cell stack structure comprising a separator, GDL and MEA, The reinforcement layer is formed in the gas diffusion layer (GDL) to reinforce the parts of the GDL and the MEA (membrane electrode assembly) which are in contact with the separator by the anode / cathode pressure difference. The reinforcement layer is a stack structure for strengthening the mechanical strength of a fuel cell, characterized in that the straight reinforcement made of a structure formed in parallel in the vertical and horizontal directions. The method according to claim 4, The reinforcing layer is a stack structure for strengthening the mechanical strength of the fuel cell, characterized in that the linear reinforcement is formed along the flow path of the separator. The method according to claim 6, The shape of the reinforcing layer is a straight line, honeycomb, stack structure for strengthening the mechanical strength of the fuel cell, characterized in that made of any one selected from the straight and curved form of the reinforcement connected to the top, bottom, left and right.

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