KR102487158B1 - Separator for fuel cell and surface treatment method of the same - Google Patents

Abstract

A separator for a fuel cell is disclosed. The disclosed separator for a fuel cell includes a reaction surface through which a reaction gas containing air flows, and a manifold portion through which reaction gas flows into and out of the reaction surface, based on the flow direction of the reaction gas flowing through the reaction surface through the manifold portion. , can form a continuous water contact angle gradient on the reaction surface.

Description

Separator for fuel cell and its surface treatment method {SEPARATOR FOR FUEL CELL AND SURFACE TREATMENT METHOD OF THE SAME}

An embodiment of the present invention relates to a fuel cell stack, and more particularly, to a metal separator for a fuel cell in which a reaction region is surface-treated and a method for treating the surface thereof.

As is known, a fuel cell generates electrical energy through an electrochemical reaction between hydrogen and oxygen, and a membrane-electrode assembly (MEA) is interposed therebetween with metal separators on both sides thereof (hereinafter, for convenience). referred to as a “separator plate”) is arranged. These fuel cells are connected in series with a plurality of unit cells and are composed of fuel cell stacks.

The fuel cell separator consists of an anode separator for supplying fuel gas (hydrogen gas) to the membrane-electrode assembly with the membrane-electrode assembly interposed therebetween, and a cathode separator for supplying oxidizing gas (air) to the membrane-electrode assembly. It consists of

The anode separator and the cathode separator form a reaction passage on the reaction surface for supplying reactive gases such as fuel gas and oxidizing gas to the membrane-electrode assembly, respectively, and cooling water is formed on the opposite surface of the reaction surface where the anode separator and the cathode separator come into contact. It forms a cooling passage through which the In addition, a manifold portion through which reaction gas and cooling water are introduced and discharged is formed on the separator.

During operation of the fuel cell, the condensed humidification water and the reaction product water are condensed and coexist on the reaction surface of the separator, and the condensed water is discharged through the reaction passage of the separator. When the condensate on the reaction surface of the separator is smoothly discharged, the reaction gas is smoothly supplied through the reaction passage, but when the condensate is not discharged smoothly, the supply of the reaction gas becomes uneven, and the corresponding cell The performance of is momentarily degraded, and when it deteriorates, it reaches an irreversible cell reverse voltage. Accordingly, the water discharge characteristic due to the water contact angle of the surface of the separator is a factor that has a major influence on the operation stability of the fuel cell.

On the other hand, on the reaction surface of the separator, a gradient occurs between an area rich in reactive gas and an insufficient area, and an area where the temperature of the cooling water is low and high due to the inlet and outlet structures of the reactive gas and cooling water. These gradients cause variables such as temperature differences and water production differences by location within the reaction surface, resulting in differences in water distribution within the reaction surface.

As such, water accumulated at a specific location on the reaction surface physically hinders the flow of the reaction gas and generates a local potential difference (mixing potential) of the electrode, thereby reducing the durability of the electrode.

Furthermore, a coating component or a substrate component is present in the form of an oxide on the surface of the separator. For example, components such as Au/Fe/Cr/Ni may exist in the form of oxides combined with oxygen on the surface of the separator, the metal separator may be made of a non-coated conductive material, and the Fe/Cr component may be present. It may exist as an oxide on the surface of the separator.

The water discharge characteristics of the separator, which has a major impact on the operation stability of the fuel cell cell, may be affected by the shape of the separator, the water contact angle of the metal surface, and the oxide and ratio of the metal surface. .

Matters described in this background art section are prepared to enhance understanding of the background of the invention, and may include matters that are not prior art already known to those skilled in the art to which this technique belongs.

Embodiments of the present invention are intended to provide a separator for a fuel cell and a surface treatment method thereof, which can improve water balance on the reaction surface by minimizing the difference in water distribution in the reaction surface by forming a continuous water contact angle gradient on the reaction surface. do.

An embodiment of the present invention includes a reaction surface through which a reaction gas including air flows, and a manifold part through which reaction gas flows into and out of the reaction surface, and a flow direction of the reaction gas flowing through the reaction surface through the manifold part. Based on, a separator for a fuel cell forming a continuous water contact angle gradient on the reaction surface may be provided.

In addition, in the fuel cell separator according to an embodiment of the present invention, a region on the side of the manifold part on the reaction surface may be partitioned into a water non-accumulation region and the remaining region into a water accumulation region.

In addition, in the fuel cell bipolar plate according to an embodiment of the present invention, a contact angle gradient portion forming a continuous water contact angle gradient between the water non-accumulation region and the water accumulation region may be provided on the reaction surface.

Further, in the separator for a fuel cell according to an embodiment of the present invention, the contact angle of the contact angle gradient part decreases from the water non-accumulation area at the inlet side of the manifold to the center of the water accumulation area, and the water accumulation area A water contact angle may increase from the center to the water non-accumulation area at the outlet side of the manifold part.

In addition, in the fuel cell bipolar plate according to an embodiment of the present invention, the water contact angle gradient portion may be formed by plasma surface treatment of the reaction surface.

In addition, in the fuel cell bipolar plate according to an embodiment of the present invention, the water contact angle gradient may be formed by removing organic materials from the reaction surface and generating OH-radicals by oxygen activated by a plasma source.

In addition, in the fuel cell separator according to an embodiment of the present invention, the plasma source is irradiated through the plasma surface treatment unit, and the water contact angle of the water contact angle gradient portion is the irradiation distance of the plasma source and the plasma surface treatment unit. can be determined by the moving speed of

In addition, an embodiment of the present invention is a surface treatment method for a separator for a fuel cell including a reaction surface for flowing a reaction gas containing air and a manifold part for inflow and outflow of a reaction gas to the reaction surface, and a plasma surface treatment unit By irradiating a plasma source to the reaction surface, adjusting the intensity of the plasma source, it is possible to form a continuous water contact angle gradient on the reaction surface.

In addition, in the surface treatment method of the fuel cell bipolar plate according to an embodiment of the present invention, the intensity of the plasma source may be adjusted by adjusting the irradiation distance of the plasma source and the moving speed of the plasma surface treatment unit.

In addition, in the surface treatment method of the bipolar plate for a fuel cell according to an embodiment of the present invention, the irradiation distance range of the plasma source may satisfy 3 to 5 mm.

In addition, in the surface treatment method of the bipolar plate for a fuel cell according to an embodiment of the present invention, the moving speed range of the plasma surface treatment unit may satisfy 1 to 4 m/min.

In addition, in the surface treatment method of the fuel cell bipolar plate according to an embodiment of the present invention, a water contact angle gradient of 20 to 90 degrees is formed on the reaction surface by adjusting the irradiation distance of the plasma source and the moving speed of the plasma surface treatment unit. can do.

In addition, the surface treatment method of the fuel cell separator according to an embodiment of the present invention, based on the flow direction of the reaction gas flowing through the reaction surface through the manifold part, on the side of the manifold part in the reaction surface The area may be partitioned into a water non-storage area and the remaining area into a water accumulation area.

In addition, in the surface treatment method of the fuel cell separator according to an embodiment of the present invention, a water contact angle gradient of 80 degrees or more is formed in the water non-accumulation region, and a water contact angle gradient of 30 degrees or less is formed in the water accumulation region. can do.

In addition, in the surface treatment method of the fuel cell separator according to an embodiment of the present invention, a water contact angle gradient in which the water contact angle decreases toward the center of the water accumulation area in the water non-accumulation area at the inlet side of the manifold part is formed. and a water contact angle gradient in which the water contact angle increases from the center of the water accumulation region to the water non-accumulation region at the outlet side of the manifold unit.

In addition, in the surface treatment method of the bipolar plate for a fuel cell according to an embodiment of the present invention, the size of the water contact angle may be inversely proportional to the strength of the plasma source.

Embodiments of the present invention increase the water discharge in the area where condensate is accumulated while maintaining the water discharge at the inlet and outlet manifold sides as a continuous water contact angle gradient is formed on the reaction surface through plasma surface treatment. can make it

Therefore, in the embodiment of the present invention, it is possible to improve the water balance in the reaction surface by minimizing the difference in water distribution in the reaction surface, thereby facilitating the flow of the reaction gas through the reaction surface, thereby increasing the durability and durability of the electrode of the fuel cell. Driving stability can be improved.

Since these drawings are for reference in explaining exemplary embodiments of the present invention, the technical idea of the present invention should not be construed as being limited to the accompanying drawings.
1 is a diagram schematically illustrating a separator for a fuel cell according to an embodiment of the present invention.
2 is a diagram schematically illustrating a plasma surface treatment unit for explaining a surface treatment method of a bipolar plate for a fuel cell according to an embodiment of the present invention.
3A to 3C are tables and graphs for explaining a surface treatment method of a separator for a fuel cell according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings, embodiments of the present invention will be described in detail so that those skilled in the art can easily carry out the present invention. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein.

In order to clearly describe the present invention, parts irrelevant to the description are omitted, and the same reference numerals are assigned to the same or similar components throughout the specification.

Since the size and thickness of each component shown in the drawings are arbitrarily shown for convenience of description, the present invention is not necessarily limited to what is shown in the drawings, and the thickness is enlarged to clearly express various parts and regions.

And, in the following detailed description, the names of the components are divided into first, second, etc. to classify them based on the relationship in which the components are the same, and the order is not necessarily limited in the following description.

Throughout the specification, when a certain component is said to "include", it means that it may further include other components without excluding other components unless otherwise stated.

In addition, terms such as "...unit", "...means", "...part", and "...member" described in the specification refer to a comprehensive unit that performs at least one function or operation. it means.

1 is a diagram schematically illustrating a separator for a fuel cell according to an embodiment of the present invention.

Referring to FIG. 1 , a fuel cell bipolar plate 100 according to an embodiment of the present invention receives hydrogen gas as a fuel gas and air as an oxidant gas (hereinafter, referred to as “reaction gas”) to generate electrochemical reactions between hydrogen and oxygen. It can be applied to a fuel cell that generates electrical energy through a phosphorus reaction.

Such a fuel cell may be composed of a fuel cell stack in which a plurality of unit cells are successively stacked, and may generate heat as a reaction by-product and discharge product water as condensate.

For example, according to an embodiment of the present invention, the fuel cell is disposed in close contact with a membrane-electrode assembly (MEA), a gas diffusion layer provided on both sides of the membrane-electrode assembly, and the gas diffusion layer. It includes a separator plate (100).

In the above membrane-electrode assembly, an anode electrode layer is formed on one surface of the electrolyte membrane with an electrolyte membrane interposed therebetween, and a cathode electrode layer is formed on the other surface of the electrolyte membrane. The anode electrode layer oxidizes the reactive gas as hydrogen gas to separate electrons and hydrogen ions, and the electrolyte membrane serves to move the hydrogen ions to the cathode electrode layer. The cathode electrode layer performs a function of generating moisture and heat by reducing reaction gas such as electrons, hydrogen ions, and separately supplied air received from the anode electrode layer.

In the above, the gas diffusion layer diffuses the reactive gas supplied through the separator 100 to the anode electrode layer and the cathode electrode layer of the membrane-electrode assembly, and has electrical conductivity and is formed on the anode electrode layer and the cathode electrode layer.

The separator 100 for a fuel cell according to an embodiment of the present invention is for supplying reactive gas to a membrane-electrode assembly through a gas diffusion layer, and is made of a material having electrical conductivity. For example, the separator 100 for a fuel cell is provided as a metal separator.

Here, the fuel cell separator 100 includes an anode separator for supplying reaction gas as hydrogen gas to the membrane-electrode assembly with the membrane-electrode assembly interposed therebetween, and an anode separator for supplying air as an oxidizing gas to the membrane-electrode assembly. It consists of a cathode separator plate. However, hereinafter, a cathode separator for supplying air to a membrane-electrode assembly as the separator 100 for a fuel cell will be described as an example.

The separator plate 100 for a fuel cell has an inlet manifold part 11 and an outlet manifold part 12 respectively forming reaction gases at both edges thereof. Further, the separator 100 forms a reaction surface 13 connected to the inlet manifold part 11 and the outlet manifold part 12 as a region corresponding to the gas diffusion layer.

A reaction passage 15 is formed on the reaction surface 13 to flow the reaction gas introduced through the inlet manifold part 11 to the outlet manifold part 12 and to supply the reaction gas to the membrane-electrode assembly. are doing In addition, a cooling water flow passage (not shown) for flowing cooling water is formed on the side opposite to the reaction surface 13 .

Furthermore, a gasket (not shown in the drawing) may be injection molded on the edge side of the reaction surface 13 of the fuel cell bipolar plate 100 . In addition, components such as Au/Fe/Cr/Ni may exist in the form of oxides combined with oxygen on the surface of the reaction surface 13, and the metal separator may be made of a non-coated conductive material, and Fe/Cr The component may be present in an oxide phase on the metal surface.

As described above, the bipolar plate 100 for a fuel cell according to an embodiment of the present invention has a structure capable of improving water balance on the reaction surface 13 by minimizing a difference in water distribution within the reaction surface 13 .

To this end, the fuel cell separator 100 according to an embodiment of the present invention is based on the flow direction of the reaction gas flowing on the reaction surface 13 through the inlet manifold part 11 and the outlet manifold part 12. As a result, a continuous water contact angle gradient 31 is formed on the reaction surface 13.

When the area on the side of the inlet and outlet manifolds 11 and 12 of the reaction surface 13 is partitioned into a water non-accumulation area S1 and the remaining area into a water accumulation area S2, the reaction surface 13 A water contact angle gradient unit 30 is provided to form a continuous water contact angle gradient 31 in the water non-accumulation region S1 and the water accumulation region S2.

In the above, the water contact angle means the angle measured at the contact point between the end point of the water drop curve and the solid surface on the liquid-solid-gas interface surface. In general, a surface with a water contact angle of 90 degrees or more is called a hydrophobic surface, and a case with a water contact angle of less than 90 degrees is called a hydrophilic surface.

In an embodiment of the present invention, in the water contact angle gradient part 30, the water contact angle decreases from the water non-accumulation area S1 on the side of the inlet manifold part 11 to the center of the water accumulation area S2, A water contact angle gradient 31 in which the water contact angle increases from the center of the accumulation region S2 to the water non-accumulation region S1 on the side of the outlet manifold unit 12 is formed.

The water contact angle gradient portion 30 is formed by plasma surface treatment of the reaction surface 13, and oxygen activated by a plasma source irradiated by the plasma surface treatment unit removes organic substances on the reaction surface 13. and can be formed by generating an OH-radical.

The water contact angle of the water contact angle gradient part 30 may be determined by the irradiation distance of the plasma source and the moving speed of the plasma surface treatment unit. The process of forming the water contact angle gradient portion 30 using such a plasma surface treatment unit will be described in detail later.

Hereinafter, a surface treatment method of the bipolar plate 100 for a fuel cell according to an embodiment of the present invention configured as described above will be described in detail with reference to the previously disclosed drawings and accompanying drawings.

2 is a diagram schematically illustrating a plasma surface treatment unit for explaining a surface treatment method of a bipolar plate for a fuel cell according to an embodiment of the present invention.

1 and 2, in an embodiment of the present invention, first, a plasma surface treatment unit 101 for plasma surface treatment of a separator 100 and a reaction surface 13 of the separator 100 is provided. do.

Here, the separation plate 100 forms the reaction passage 15 on the reaction surface 13, and a gasket (not shown) is injection molded on the edge side of the reaction surface 13.

In the above, the plasma surface treatment unit 101 is for modifying the surface of the reaction surface 13 by using the energy of the plasma source PS, and has first and second electrode parts 103 and 105, for example. A plasma source irradiation unit 107 forming a discharge space is included.

When the plasma surface treatment unit 101 injects a discharge gas into the discharge space of the plasma source irradiation unit 107 and connects power to the first electrode unit 103 while the second electrode unit 105 is grounded, A plasma source (PS) is generated in the discharge space by a voltage difference between the first electrode part 103 and the second electrode part 105, and the plasma source PS is applied to the reaction surface 13 of the separator 100. investigate with

Since the configuration of the plasma surface treatment unit 101 is composed of a plasma surface modification device widely known in the art, a detailed description of the configuration will be omitted in this specification.

The plasma surface treatment unit 101 as described above can move the plasma source irradiation unit 107 in the vertical direction by a driving means 111 of known technology such as a servo motor and adjust the plasma source irradiation distance (position).

In addition, the plasma surface treatment unit 101 can move the plasma source irradiator 107 in a horizontal direction by the driving means 111 and adjust the moving speed of the plasma source irradiator 107 .

In the embodiment of the present invention, a continuous water contact angle gradient 31 is formed on the reaction surface 13 using the plasma surface treatment unit 101 as described above. ), and a continuous water contact angle gradient 31 may be formed on the reaction surface 13.

Here, the intensity of the plasma source PS may be adjusted by adjusting the irradiation distance of the plasma source PS by the plasma source irradiator 107 and the moving speed of the plasma source irradiator 107 .

For example, in an embodiment of the present invention, the irradiation distance range of the plasma source PS satisfies 3 to 5 mm, and the moving speed range of the plasma source irradiator 107 satisfies 1 to 4 m/min.

Therefore, in the embodiment of the present invention, the plasma source PS is irradiated to the reaction surface 13 of the separation plate 100 through the plasma source irradiator 107, and the plasma source irradiator 107 through the driving means 111 Adjusting the irradiation distance and the moving speed of the plasma source irradiation unit 107, it is possible to form a water contact angle gradient 31 of 20 to 90 degrees on the reaction surface 13.

Describing this process in detail, when the plasma source PS is irradiated to the reaction surface 13 of the separator 100 through the plasma source irradiation unit 107, oxygen activated by the plasma source PS reacts. Organic substances on the surface of the cotton 13 are removed, and OH-radicals having excellent affinity for water are generated on the surface.

The concentration of the activated oxygen is higher as the irradiation distance of the plasma source irradiator 107 to the reaction surface 13 is closer, and becomes lower as the distance from the reaction surface 13 is increased. And, the concentration of the activated oxygen is higher as the moving speed of the plasma source irradiator 107 is slower, and lower as the moving speed is faster.

That is, the intensity of the plasma source PS irradiated from the plasma source irradiator 107 increases as the irradiation distance increases and the irradiation time increases, and decreases as the irradiation distance increases and the irradiation time decreases.

In the embodiment of the present invention, by using such plasma surface treatment characteristics, the irradiation distance of the plasma source PS and the moving speed of the plasma source irradiation unit 107 are adjusted, and the water contact angle gradient of 20 to 90 degrees on the reaction surface 13 ( 31) can be formed. For example, in the embodiment of the present invention, a water contact angle gradient 31 of 80 degrees or more is formed in the water non-accumulation region S1 of the reaction surface 13, and a water contact angle of 30 degrees or less is formed in the water accumulation region S2. A gradient 31 is formed.

That is, in the embodiment of the present invention, a water contact angle gradient 31 is formed in which the water contact angle decreases from the water non-accumulation region S1 on the side of the inlet manifold part 11 to the center of the water accumulation region S2, A water contact angle gradient 31 in which the water contact angle increases from the center of the water accumulation region S2 toward the water non-accumulation region S1 on the side of the outlet manifold unit 12 may be formed.

Therefore, in the embodiment of the present invention, the intensity of the plasma source (PS) irradiated to the water non-accumulation region (S1) of the reaction surface 13 is minimized, and the water contact angle in the water non-accumulation region (S1) is 80 degrees or more. , the intensity of the plasma source PS irradiated to the water accumulation region S2 is maximized, and the water contact angle in the water accumulation region S2 is maintained at 30 degrees or less.

In other words, in the embodiment of the present invention, since the magnitude of the water contact angle is inversely proportional to the intensity of the plasma source PS, the intensity of the plasma source PS is minimized and the magnitude of the water contact angle in the water non-accumulation region S1 is increased. It is possible to maximize the strength of the plasma source PS and reduce the water contact angle in the water accumulation region S2.

In the above, when the size of the water contact angle increases, the contact resistance of water to the reaction surface 13 increases, and when the size of the water contact angle decreases, the contact resistance of water to the reaction surface 13 decreases and has hydrophilicity.

Meanwhile, referring to FIGS. 3A to 3C, an embodiment of the present invention is described. As conditions of the plasma source irradiation distance, the moving speed of the plasma source irradiator, and the number of surface treatments shown in FIGS. It is possible to form a continuous water contact angle gradient 31 of 90 degrees.

Accordingly, as shown in FIG. 3C, the intensity of the plasma source is minimized by maximizing the irradiation distance of the plasma source and the moving speed of the plasma source irradiator on the side of the manifold inlet of the reaction surface, thereby maximizing the water contact angle at the inlet side of the manifold. .

Between the manifold inlet and the center of the reaction surface, the irradiation distance of the plasma source and the moving speed of the plasma source irradiator are reduced, and the water contact angle between the manifold inlet and the center can be reduced by increasing the intensity of the plasma source. there is.

A water contact angle at the center side of the reaction surface may be minimized by maximizing the intensity of the plasma source by minimizing the irradiation distance of the plasma source and the moving speed of the plasma source irradiator at the center side of the reaction surface.

Between the manifold outlet and the center of the reaction surface, the irradiation distance of the plasma source and the moving speed of the plasma source irradiator are increased, and the water contact angle between the manifold outlet and the center can be increased by reducing the strength of the plasma source. there is.

In addition, the intensity of the plasma source is minimized by maximizing the irradiation distance of the plasma source and the moving speed of the plasma source irradiator at the manifold outlet side of the reaction surface, thereby maximizing the water contact angle at the manifold inlet side.

Therefore, in the embodiment of the present invention, a water contact angle gradient 31 is formed in which the water contact angle decreases from the manifold inlet side of the reaction surface to the center, and the water contact angle increases from the center side to the manifold inlet side. A water contact angle gradient 31 may be formed.

According to the embodiment of the present invention as described so far, a continuous water contact angle gradient 31 is formed on the reaction surface 13 through plasma surface treatment that adjusts the irradiation distance of the plasma source and the moving speed of the plasma source irradiator. Accordingly, it is possible to increase the water discharge property in the area where the condensed water is accumulated while maintaining the water discharge property at the inlet and outlet manifold parts 11 and 12 side.

Thus, in the embodiment of the present invention, it is possible to improve the water balance in the reaction surface 13 by minimizing the difference in water distribution in the reaction surface 13, and as a result, the reaction gas flows smoothly through the reaction surface 13. By doing so, it is possible to improve the electrode durability and operation stability of the fuel cell.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and it is possible to carry out various modifications within the scope of the claims and detailed description of the invention and the accompanying drawings, and this is also the present invention. It goes without saying that it falls within the scope of the invention.

11 ... inlet manifold part
12 ... outlet manifold part
13... Reaction plane
15... reaction flow
30 ... water contact angle gradient
31... water contact angle gradient
100... Separator
101... Plasma surface treatment unit
103... first electrode part
105 ... second electrode part
107... Plasma source irradiation unit
111... driving means
PS... plasma source
S1 ... water storage area
S2... water accumulation area

Claims (13)

A separator for a fuel cell comprising a reaction surface through which a reaction gas containing air flows, and a manifold portion through which reaction gas flows into and out of the reaction surface,
Forming a continuous water contact angle gradient on the reaction surface based on the flow direction of the reaction gas flowing on the reaction surface through the manifold unit,
In the reaction surface, the area on the side of the manifold part is partitioned into a water non-accumulation area and the remaining area is divided into a water accumulation area, and a continuous water contact angle gradient is formed in the water non-accumulation area and the water accumulation area on the reaction surface. A contact angle gradient is provided,
In the contact angle gradient, the water contact angle decreases from the water storage area at the inlet side of the manifold to the center of the water storage area, and the water contact angle decreases from the center of the water storage area to the water storage area at the outlet side of the manifold. Separator for fuel cell, characterized in that the water contact angle increases. delete delete According to claim 1,
The water contact angle gradient part is formed by plasma surface treatment of the reaction surface. According to claim 1,
The water contact angle gradient part,
A bipolar plate for a fuel cell, characterized in that formed by oxygen activated by a plasma source removing organic substances from the reaction surface and generating OH-radicals. According to claim 5,
The plasma source is irradiated through a plasma surface treatment unit,
The water contact angle of the water contact angle gradient part is determined by the irradiation distance of the plasma source and the moving speed of the plasma surface treatment unit. A surface treatment method for a separator for a fuel cell comprising a reaction surface through which a reaction gas containing air flows, and a manifold portion through which reaction gas flows into and out of the reaction surface,
A plasma source is irradiated to the reaction surface by a plasma surface treatment unit, the intensity of the plasma source is adjusted, and a continuous water contact angle gradient is formed on the reaction surface;
Based on the flow direction of the reaction gas flowing through the reaction surface through the manifold part, when the area on the side of the manifold part in the reaction surface is partitioned into a water non-accumulation area and the remaining area into a water accumulation area, the manifold A water contact angle gradient in which a water contact angle decreases from the water accumulation region at the inlet side of the fold part to the center of the water accumulation region is formed, and from the center of the water accumulation region to the water accumulation region at the outlet side of the manifold part A surface treatment method for a separator for a fuel cell, characterized in that forming a water contact angle gradient in which the water contact angle increases. According to claim 7,
The method of treating the surface of a separator for a fuel cell, characterized in that the intensity of the plasma source is adjusted by adjusting the irradiation distance of the plasma source and the moving speed of the plasma surface treatment unit. According to claim 8,
The irradiation distance range of the plasma source satisfies 3 to 5 mm,
The surface treatment method of a separator for a fuel cell, characterized in that the moving speed range of the plasma surface treatment unit satisfies 1 to 4 m / min. According to claim 9,
The surface treatment method of a separator for a fuel cell, characterized in that by adjusting the irradiation distance of the plasma source and the moving speed of the plasma surface treatment unit to form a water contact angle gradient of 20 to 90 degrees on the reaction surface. According to claim 10,
Forming a water contact angle gradient of 80 degrees or more in the water non-accumulation area, and forming a water contact angle gradient of 30 degrees or less in the water accumulation area. delete According to claim 7,
The surface treatment method of a separator for a fuel cell, characterized in that the size of the water contact angle is inversely proportional to the intensity of the plasma source.

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