KR101394281B1 - Separator for proton exchange membrane fuel cell with patterned for water movement in channel and proton exchange membrane fuel cell using the same - Google Patents

Abstract

Disclosed is a separator for a polymer electrolyte fuel cell having a pattern for movement of moisture in a channel, and a polymer electrolyte fuel cell using the separator. The polymer electrolyte fuel cell of the present invention comprises a membrane-electrode assembly having a polymer electrolyte membrane disposed between an anode and a cathode, first and second gas diffusion layers disposed on both sides of the membrane-electrode assembly, A plurality of unit cells arranged on both sides of the first and second gas diffusion layers and having first and second separation plates on which channels are formed; Two end plates disposed on both sides of the plurality of unit cells; And fastening means for fastening the end plates. A hydrophobic / hydrophilic pattern is formed on the channel of the separator adjacent to the cathode of the first and second separator plates for movement of water. According to the present invention, a hydrophobic / hydrophilic pattern is formed in the channel of the separator to smooth the movement of water, so that water overflow is prevented to prevent performance deterioration and shortening of life, There is an excellent effect.

Description

Technical Field [0001] The present invention relates to a separator for a polymer electrolyte fuel cell, and a polymer electrolyte fuel cell using the separator. [0001] The present invention relates to a separator for a polymer electrolyte fuel cell and a polymer electrolyte fuel cell using the separator,

The present invention relates to a fuel cell, and more particularly, to a separator for a polymer electrolyte fuel cell having a pattern for movement of moisture in a channel and a polymer electrolyte fuel cell using the same.

Fuel cells are energy conversion devices that directly convert the chemical energy generated by the oxidation of fuel into electrical energy. Fuel cells have been developed in various forms and structures depending on the type of fuel used in the battery. Polymer electrolyte fuel cells use polymer membranes with hydrogen ion exchange properties as electrolytes and are also called solid polymer electrolyte fuel cell (SPEFC), solid polymer fuel cell (SPFC), and polymer electrolyte fuel cell (PEFC). These polymer electrolyte fuel cells have high efficiency, high current density and power density, short start-up time, and fast response characteristics to load changes. As a result, they can be used in a variety of fields such as power source for automobiles, mobile power generation, And the like.

Polymer electrolyte fuel cells are disclosed in U.S. Patent Nos. 7,862,922 and 7,901,836. The stack of a polymer electrolyte fuel cell disclosed in these patent documents is basically composed of a plurality of unit cells (single cells) and two end plates (end plates).

A unit cell of a polymer electrolyte fuel cell includes an anode, a cathode, a polymer electrolyte membrane, two gas diffusion layers (GDLs), a plurality of gaskets, And separators. The polymer electrolyte membrane acts as a carrier of hydrogen ions between the anode and the cathode, and also serves to prevent contact between oxygen and hydrogen. A membrane-electrode assembly (MEA) in which two electrodes, an anode and a cathode, are bonded to a polymer electrolyte membrane by hot-pressing, is called a membrane-electrode assembly (MEA).

The separator is an electrically conductive plate disposed on both sides of the membrane-electrode assembly and also referred to as a bipolar plate or a flow field plate. An anode side channel is formed on one side of the separator and a cathode side channel is formed on the other side. The end plates are fastened with a tie rod or air pressure to reduce the contact resistance between the components, and have connectors for the outlet, inlet, cooling water circulation hole, and power output of the reaction gas.

On the other hand, in the anode of a polymer electrolyte fuel cell, hydrogen cations (protons) and electrons are generated by the oxidation reaction of hydrogen. The generated hydrogen cations and electrons move to the cathode through the electrolyte membrane and the separator, respectively. In the cathode, water, that is, water is generated by hydrogen cations and oxygen reduction reactions of electrons and oxygen, and electric power is generated from the flow of electrons.

It is very important to maintain water balance in the conventional polymer electrolyte fuel cell as described above. If the humidity inside the fuel cell is not maintained at a certain level, the moisture on the surface of the membrane-electrode assembly is removed and dried to lower the ion conductivity. As a result, the performance of the stack deteriorates and the life of the membrane- do. In the electrochemical reaction process, when the water generated from the anode is not discharged smoothly and remains in the gas diffusion layer, the water flooding occurs because the water vapor condenses on the gas diffusion layer, ) Is generated. In addition, the water is condensed at the anode, which interferes with the flow of the fuel, thereby deteriorating the performance. Residual moisture in the channel interferes with cold start.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art. An object of the present invention is to provide a separator for a polymer electrolyte fuel cell having a hydrophobic / hydrophilic pattern for movement of moisture in a channel and a polymer electrolyte fuel cell using the separator.

It is another object of the present invention to provide a separator for a polymer electrolyte fuel cell and a polymer electrolyte fuel cell using the separator, which can prevent the water overflow and prevent a reduction in performance and a shortening of life.

It is another object of the present invention to provide a separator for a polymer electrolyte fuel cell and a polymer electrolyte fuel cell using the same, which can improve the characteristics of cold starting.

According to an aspect of the present invention, a separation plate for a new polymer electrolyte fuel cell is provided. In the separator for a polymer electrolyte fuel cell according to the present invention, a channel is formed on one surface, and a hydrophobic / hydrophilic pattern is formed on the surface of the channel for transferring moisture in the channel. The hydrophobic / hydrophilic pattern is composed of a hydrophobic surface layer formed on the surface of the channel and a plurality of hydrophilic surface layers formed on the surface of the hydrophobic surface layer.

A polymer electrolyte fuel cell according to another aspect of the present invention includes a membrane-electrode assembly having a polymer electrolyte membrane disposed between an anode and a cathode, first and second gas diffusion layers disposed on both sides of the membrane- A plurality of unit cells arranged on both sides of the first and second gas diffusion layers and having first and second separation plates on which channels are formed; Two end plates disposed on both sides of the plurality of unit cells; And hydrophobic / hydrophilic patterns are formed in the first and second separation plates for movement of water in the channels of the separation plates adjacent to the cathodes.

The separator for a polymer electrolyte fuel cell and the polymer electrolyte fuel cell using the same according to the present invention have hydrophobic / hydrophilic patterns formed in the channels of the separator to smooth water movement, so that water overflow is prevented, Can be prevented, and the characteristics of the cold start can be improved.

1 is a view showing a configuration of a polymer electrolyte fuel cell according to the present invention.
FIG. 2 is a cross-sectional view of a polymer electrolyte fuel cell according to the present invention, in which the structure of a unit cell is separated.
3 is a partially enlarged cross-sectional view of a second separator plate in the polymer electrolyte fuel cell according to the present invention.
4 is a partially enlarged cross-sectional view for explaining the action of the hydrophobic / hydrophilic pattern in the polymer electrolyte fuel cell according to the present invention.

Other objects, specific advantages and novel features of the present invention will become more apparent from the following detailed description and preferred embodiments with reference to the accompanying drawings.

Hereinafter, preferred embodiments of a separator for a polymer electrolyte fuel cell and a polymer electrolyte fuel cell using the same according to the present invention will be described in detail with reference to the accompanying drawings.

1, a polymer electrolyte fuel cell according to the present invention includes a plurality of unit cells 10, two end plates 12, two current collectors 14, And a plurality of tie rods 16 as fastening means. The end plates 12 are disposed on both sides of a plurality of stacked unit cells 10, respectively. The current collectors 14 are respectively disposed inside the end plates 12 for current collection. The tie rods 16 are coupled to the end plates 12 to impart a fastening force to the unit cells 10. The tightening force applied to the unit cells 10 can be replaced with air pressure.

The unit cells 10 include a membrane electrode assembly 20, first and second gas diffusion layers 30 and 32, first and second gas diffusion layers 30 and 32, 1 and second separator plates 40, 50, respectively. The membrane-electrode assembly 20 includes an anode 22 for generating electrochemical oxidation of hydrogen with fuel, a cathode 24 for generating electrochemical reduction of oxygen with an oxidizing agent, And the polymer electrolyte membrane 26 disposed in the polymer electrolyte membrane.

The first gas diffusion layer 30 is disposed on one side of the anode 22 and the second gas diffusion layer 32 is disposed on one side of the cathode 24 to uniformly diffuse the gas. The first separator plate 40 is disposed on one side of the first gas diffusion layer 30 and the second separator plate 50 is disposed on one side of the second gas diffusion layer 32. A plurality of gaskets 60 are disposed between the first and second gas diffusion layers 30 and 32 and between the anode 22 and the cathode 24 so as to maintain the airtightness.

Referring to FIGS. 1 and 2, the first separator plate 40 has a plurality of channels 42 formed on one side of the first separator plate 40 so as to be adjacent to the anode 24. The second separator plate 50 has a plurality of channels 52 formed on one side thereof so as to be adjacent to the cathode 52. Hydrogen is supplied to the channels 42 of the first separator plate 40 and oxygen is supplied to the channels 52 of the second separator plate 50. [

Referring to FIGS. 2 and 3, a hydrophobic / hydrophilic pattern 100 is formed on the surface of the channel 52 for movement of water. The hydrophobic / hydrophilic pattern 100 is composed of a hydrophobic surface layer 102 formed on the surface of the channel 52 and a plurality of hydrophilic surface layers 104 formed on the hydrophobic surface layer 102. The hydrophobic surface layer 102 is also formed on one surface of the second separation plate 50 on which the channel 52 is formed. The hydrophilic surface layers 104 are arranged at regular intervals on the surface of the hydrophobic surface layer 102 formed in the channel 52. Each of the hydrophobic surface layer 102 and the hydrophilic surface layer 104 may be formed by coating, sputtering, or the like of a hydrophobic material and a hydrophilic material.

The hydrophilic surface layers 104 may be formed in various shapes such as a dome pattern, a dot pattern, a polygon pattern, and the like. The size of the nanometer may be the size of the micrometer As shown in FIG. Illustratively, the hydrophilic surface layers 104 are formed in a hemispherical pattern. The hemispherical pattern may be referred to as an embossing pattern which is convexly protruded.

 In the cathode 24 of the polymer electrolyte fuel cell having such a structure, as shown in Fig. 4, water (i.e., water 2) is generated by an oxygen reduction reaction of hydrogen cations and electrons and oxygen. The water 2 does not remain in the second gas diffusion layer 32 but migrates to the channels 52 while being concentrated on the hydrophilic surface layers 104. At this time, a water droplet 4 is generated on the hydrophilic surface layers 104 in the channel 52 to prevent water overflow. The droplet 4 is smoothly discharged out of the channels 52 while moving to the surface of the hydrophobic surface layer 102 on the hydrophilic surface layer 104. As the size of the water droplet 4 becomes larger than the size of the hydrophilic surface layer 104,

On the other hand, when one surface of the second separator plate 50 and the surface of the channel 52 are formed as a hydrophilic surface layer, moisture generated in the membrane-electrode assembly 20, that is, water, Lt; RTI ID = 0.0 > 52 < / RTI > However, the strong adhesion of the water to the hydrophilic surface layer of the channel 52 prevents water from being well discharged out of the channel 52. When one surface of the second separator plate 50 and the surface of the channel 52 are formed of a hydrophobic surface layer, the water is separated from the inside or the surface of the second gas diffusion layer 32, And remains on the interface of the plate 50. And water droplets are grown to block the second channels 52.

In the second separator 50 of the polymer electrolyte fuel cell according to the present invention, the moisture generated by the oxygen reduction reaction flows smoothly from the second gas diffusion layer 32 to the channels 52 by the hydrophobic / And the water droplets generated in the channels 52 are smoothly discharged out of the channel 52 to prevent water overflow. Therefore, the performance of the polymer electrolyte fuel cell is prevented from being reduced and the service life shortened, thereby improving the reliability and improving the characteristics of the cold start.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

10: unit cell 12: end plate
20: membrane-electrode assembly 22: anode
24: cathode 26: polymer electrolyte membrane
30: first gas diffusion layer 32: second gas diffusion layer
40: first separator plate 42: channel
50: second separator plate 52: channel
60: gasket 100: hydrophobic / hydrophilic pattern
102: hydrophobic surface layer 104: hydrophilic surface layer

Claims (8)

Wherein a channel is formed on one side of the channel and a hydrophobic / hydrophilic pattern is formed on a surface of the channel for movement of moisture in the channel. The method according to claim 1,
Wherein the hydrophobic / hydrophilic pattern comprises a hydrophobic surface layer formed on a surface of the channel and a plurality of hydrophilic surface layers formed on a surface of the hydrophobic surface layer. 3. The method of claim 2,
Wherein the plurality of hydrophilic surface layers are arranged at regular intervals in the hydrophobic surface layer. The method according to claim 2 or 3,
Wherein the hydrophobic surface layer is further formed on the one surface on which the channel is formed. A membrane-electrode assembly having a polymer electrolyte membrane disposed between an anode and a cathode, first and second gas diffusion layers disposed on both sides of the membrane-electrode assembly, and first and second gas diffusion layers disposed on both sides of the first and second gas diffusion layers A plurality of stacked unit cells having first and second separator plates each having a channel formed therein;
Two end plates disposed on both sides of the plurality of unit cells;
And fastening means for fastening the end plates,
Wherein a hydrophobic / hydrophilic pattern is formed on the channel of the separator adjacent to the cathode of the first and second separators to move moisture therein. 6. The method of claim 5,
Wherein the hydrophobic / hydrophilic pattern comprises a hydrophobic surface layer formed on a surface of the channel and a plurality of hydrophilic surface layers formed on a surface of the hydrophobic surface layer. The method according to claim 6,
Wherein the plurality of hydrophilic surface layers are arranged at regular intervals in the hydrophobic surface layer. 8. The method according to claim 6 or 7,
Wherein the hydrophobic surface layer is further formed on one surface of the first and second separator plates on which the channel is formed.

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