KR101932424B1 - Composite material for bipolar plate of fuel cell, bipolar plate of fuel cell and manufacturing method of the same - Google Patents

Abstract

A composite material for a fuel cell separator comprising a first conductive continuous fiber bundle and an impregnated resin aligned in one direction and comprising a plurality of layers of a first conductive continuous fiber bundle aligned in one direction, And a fuel cell separator formed by a composite material for one fuel cell separator.

Description

Technical Field [0001] The present invention relates to a composite material for a fuel cell separator, a fuel cell separator, and a method for manufacturing the same. BACKGROUND ART [0002]

A fuel cell separator, and a method for manufacturing the same.

A fuel cell is a power generation system that produces electricity by electrochemical reaction of hydrogen and oxygen. It can be composed of a stack, which is a main component for producing electricity directly, and other devices that assist in the operation of the stack.

The unit cell includes a membrane electrode assembly (MEA) and a membrane electrode assembly (MEA), which are provided on both sides of the membrane electrode assembly, And battery separators.

The membrane electrode assembly has a polymer electrolyte membrane selectively passing only hydrogen ions, and an anode electrode and a cathode electrode can be bonded to both sides of the polymer electrolyte membrane.

The fuel cell separator plays a role of collecting the current generated in the unit cell and serves as a separator for maintaining insulation and discharges water generated by supplying gas (hydrogen, oxygen) to a gas diffusion layer (GDL) Can play a role.

Such a fuel cell separator plate should be stable in the oxidizing and reducing atmosphere of the anode electrode and the cathode electrode, sufficiently prevent gas mixing, and have sufficient electric conductivity.

Conventional commercialized graphite separators have corrosion resistance and good electrical conductivity, but they are resistant to mechanical shock or vibration and must maintain a thickness of more than a certain level. This causes a decrease in the efficiency of the fuel cell stack and a problem of high cost, There is a problem of gas permeability.

In one embodiment of the present invention, there is provided a composite material for a fuel cell separator which realizes excellent processability, excellent productivity, excellent molding processability, excellent corrosion resistance, low contact resistance and excellent electrical conductivity.

In another embodiment of the present invention, there is provided a fuel cell separator formed by the composite material for the fuel cell separator

In another embodiment of the present invention, a method of manufacturing the fuel cell bipolar plate is provided.

However, the technical problem to be solved by the present invention is not limited to the above-mentioned problems, and other matters not mentioned can be clearly understood by those skilled in the art from the following description.

In one embodiment of the present invention, the first conductive continuous fiber bundle and the impregnated resin are aligned in one direction, and the first conductive continuous fiber bundle aligned in one direction is a single layer, A composite material for a fuel cell separator is provided.

The plurality of layers may be parallel to each other.

When the composite material for at least one fuel cell separator is formed as a fuel cell separator, both end faces of the first conductive continuous fiber bundle may be exposed on the upper and lower surfaces of the fuel cell separator, respectively have.

Wherein the composite material for the fuel cell separator includes two surfaces each of which both end faces of the first conductive continuous fiber bundle are exposed and side surfaces therebetween and a composite material for a plurality of fuel cell separators is formed of a fuel cell separator And may be attached to the side surface.

When the composite material for at least one fuel cell separator is formed of a fuel cell separator, the longitudinal direction of the first conductive continuous fiber bundle may be perpendicular to the upper surface and the lower surface of the fuel cell separator.

The composite material for the fuel cell separator may not include the conductive filler separately.

The length of the first conductive continuous fiber bundle may be about 0.1 mm to about 2.0 mm.

The first conductive continuous fiber bundle is formed by bundling the first conductive continuous fibers, for example, on an average of about 1,000 to about 48,000 fibers, and the thickness of the first conductive continuous fiber bundle is about 0.1 mm to about 0.2 mm, and the width may be about 1.0 mm to about 20.0 mm.

The linear density of the first conductive continuous fibers may be from about 800 g / km to about 4,000 g / km.

The weight ratio of the impregnation resin to the first conductive continuous fiber bundle may be from about 1:40 to about 1:99.

The layer may comprise from about 1 to about 100 layers.

The thickness in a direction perpendicular to the layer may be from about 0.12 mm to about 22.0 mm.

The width in a direction parallel to the layer and perpendicular to the longitudinal direction of the first conductive continuous fiber bundle may be about 25.0 mm to about 100.0 mm.

The first conductive continuous fiber may include an organic fiber, an inorganic fiber, or both, the surface of which is coated with a conductive filler or the conductive filler is dispersed inside the fiber.

The layer may or may not further comprise a second conductive continuous fiber bundle aligned in a direction different from the one direction.

In another embodiment of the present invention, a composite material for at least one fuel cell separator is formed, and both end faces of the first conductive continuous fiber bundle may be exposed on the upper and lower surfaces, respectively.

Wherein the composite material for the fuel cell separator includes two surfaces each of which both end faces of the first conductive continuous fiber bundle are exposed and side surfaces therebetween, and a plurality of composite materials for fuel cell separator are attached .

The longitudinal direction of the first conductive continuous fiber bundle may be perpendicular to the upper surface and the lower surface of the fuel cell bipolar plate.

The total thickness of the fuel cell separator may be about 0.1 mm to about 2.0 mm.

The contact resistance of the fuel cell separator may be about 20 m? 占² m ² or less, and the electric conductivity may be about 100 S / cm to about 200 S / cm.

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In another embodiment of the present invention, there is provided a method of forming a conductive continuous fiber sheet, comprising: forming a first conductive continuous fiber bundle sheet; The first conductive continuous fiber bundle sheets are laminated and then impregnated with the impregnated resin and dried, or the first conductive continuous fiber bundle sheet and the impregnated resin film are alternately laminated, followed by thermocompression bonding, Forming a preliminary composite; Forming the composite material for a fuel cell separator by cutting the preliminary composite material perpendicularly to the longitudinal direction of the first conductive continuous fiber bundle at regular intervals within a range of 0.1 mm to 2.0 mm; And fabricating a fuel cell separator such that both end faces of the first conductive continuous fiber bundle are exposed to the upper and lower surfaces of the fuel cell separator plate by the composite material for the at least one fuel cell separator, respectively; The present invention also provides a method of manufacturing a fuel cell bipolar plate.

The composite material for the fuel cell separator and the fuel cell separator can realize excellent processability, excellent productivity, excellent molding processability, excellent corrosion resistance, low contact resistance and excellent electric conductivity.

1 is a schematic perspective view of a composite material for a fuel cell bipolar plate according to an embodiment of the present invention.
2 is a schematic perspective view of a fuel cell bipolar plate according to another embodiment of the present invention.
3 is a schematic process flow diagram of a fuel cell bipolar plate according to another embodiment of the present invention.
Fig. 4 is a schematic diagram for explaining step (S1) in the process flow chart of Fig. 3;
5 is a schematic diagram for explaining step 2 (S2) in the process flow chart of FIG.
Fig. 6 is a schematic diagram for explaining step S3 in the process flow chart of Fig. 3. Fig.
FIG. 7 is a schematic diagram illustrating step (S4) in the process flow chart of FIG.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art to which the present invention pertains. The present invention may be embodied in many different forms and is not limited to the embodiments described herein.

In order to clearly illustrate the present invention, parts not related to the description are omitted, and the same or similar components are denoted by the same reference numerals throughout the specification.

In the drawings, the thickness is enlarged to clearly represent the layers and regions. In the drawings, for the convenience of explanation, the thicknesses of some layers and regions are exaggerated.

Hereinafter, formation of an arbitrary structure in the upper part (or lower part) or the upper part (or lower part) of the substrate means not only that an arbitrary constitution is formed in contact with the upper surface (or lower surface) of the substrate, And any configuration formed on (or under) the substrate.

In one embodiment of the present invention, the first conductive continuous fiber bundle and the impregnated resin are aligned in one direction, and the first conductive continuous fiber bundle aligned in one direction is a single layer, A composite material for a fuel cell separator is provided. 1 schematically shows a perspective view of a composite material 100 for a fuel cell separator according to the present invention. As shown in FIG. 1, the first conductive continuous fiber bundle 110 is formed in the impregnated resin 120, A plurality of layers may be included.

The first conductive continuous fiber bundles 110 aligned in one direction can be aligned in one direction on a single plane and the neighboring first conductive continuous fiber bundles 110 are partially or wholly adhered to each other, So that the first conductive continuous fiber bundle 110 sheet can be formed as a single layer. That is, the first conductive continuous fiber bundle 110 sheets may be included in the impregnated resin 120.

Specifically, the plurality of layers may be parallel to each other, so that the first conductive continuous fiber bundle 110 may be aligned in the one direction within the impregnated resin 120. [

Recently, a polymer composite separator including a polymer resin and a conductive fiber has been used. However, in order to satisfy the required electrical conductivity and thermal conductivity, the polymer composite separator requires addition of a large amount of conductive filler in addition to the conductive fiber And the process becomes complicated. Therefore, time and cost are further consumed, resulting in low productivity. Further, when such a conductive filler is contained in a large amount, there is a problem that molding processability is deteriorated. In addition, when the conductive fiber or the conductive filler is nonuniformly dispersed in the fuel cell separator without directionality, the flow of current becomes uneven and the flow of current can be partially cut off by the polymer resin having the insulating performance, The electrical conductivity can be reduced.

Accordingly, in one embodiment of the present invention, the composite material 100 for the fuel cell separator includes the first conductive continuous fiber bundle 110 and the impregnated resin 120, which are aligned in one direction, The length L of the first conductive continuous fiber bundle 110 aligned in one direction can be perpendicular to the upper and lower surfaces of the separator plate, The longitudinal direction L of the first conductive continuous fiber bundles 110 in the plate may be formed to be the same as the flow direction of the current. As a result, a current can flow along the first conductive continuous fiber bundle 110 when the fuel cell including the separator made of the composite material 100 for a fuel cell separator is driven, It is possible to effectively prevent the current flow from being cut off.

As a result, the composite material 100 for a fuel cell separator is not formed of a metal material, so that it has excellent corrosion resistance and does not contain a large amount of conductive filler, thereby providing excellent processability, productivity and molding processability. At the same time, It is possible to realize a low contact resistance and excellent electric conductivity since the disconnection can be prevented while being more uniform.

In the present specification, the upper and lower surfaces of the fuel cell separator plate are a pair of surfaces in contact with the gas diffusion layer, the membrane electrode assembly, or the like in the fuel cell or the unit cell, and means a pair of surfaces perpendicular to the direction of current flow . The fuel cell separator is symmetrical in shape and the pair of faces need not be divided into an upper portion and a lower portion. However, since the upper and lower surfaces are referred to as the upper and lower surfaces for convenience of explanation, May be arbitrarily selected, and is not particularly limited.

Also, the first conductive continuous fiber bundle 110 may be referred to as a fiber bundle, and the first conductive continuous fibers may be formed by bundling, for example, an average of 1,000 to 48,000 fibers as the filament filaments. The fiber filaments may include monofilaments, multifilaments, or all of them. The monofilament refers to a yarn formed with one strand, and the multifilament may mean a yarn formed by twisting a plurality of strands.

The first conductive continuous fiber bundle 110 can be formed by, for example, immersing the first conductive continuous fibers in a composition containing the binder resin, or by spraying a composition containing the binder resin thereto and focusing them.

The binder resin may be any of those known in the art and may be selected from, for example, an acrylic resin, a methacrylic resin, a polyisoprene, a vinyl resin, an epoxy resin, a urethane resin, a cellulosic resin, But it is not limited thereto.

The first conductive continuous fiber bundle 110 may include an organic fiber, an inorganic fiber, or all of them, the surface of which is coated with a conductive filler or the conductive filler is dispersed in the continuous fiber bundle , So that current can easily flow along these fibers.

The organic fibers include, for example, synthetic fibers such as polypropylene fibers and aramid fibers. The inorganic fibers include, for example, glass fibers, carbon fibers, and ceramic fibers.

More specifically, the first conductive continuous fiber bundles 110 may be formed of one selected from the group consisting of PAN, pitch and rayon carbon fibers; Carbon nanofibers; Activated carbon fiber; And a combination of these.

The carbon fiber or the carbon nanofiber may be selected from, for example, polyacrylonitrile (PAN), polybenzylimidazole (PBI), cellulose, phenol, and pitch. May be formed from one or more precursors, but are not limited thereto.

The length of the first conductive continuous fiber bundle 110 may be about 0.1 mm to about 2.0 mm. When the fuel cell separator is formed of the composite material 100 for the fuel cell separator by having a length within the above range, the longitudinal direction L of the first conductive continuous fiber bundle 110 may be the same as the length So that current can flow along the first conductive continuous fiber bundle 110, so that the flow of the current is uniformed and the disconnection is prevented, so that excellent electrical conductivity and low contact resistance can be obtained Can be implemented.

When the length of the first conductive continuous fiber bundle 110 is less than about 0.1 mm, the orientation of the fiber in the process of impregnating the first conductive continuous fiber bundle 110 aligned in the one direction with the impregnated resin 120 The first conductive continuous fiber bundle 110 may be easily disturbed and difficult to maintain alignment in one direction. When the fuel cell bipolar plate is formed due to the limitation of the thickness of the fuel cell separator, Can not be formed so as to be parallel to the upper and lower surfaces of the fuel cell separator plate.

However, if the layer formed of the first conductive continuous fiber bundles 110 aligned in one direction is parallel to the upper and lower surfaces of the fuel cell bipolar plate as described above, A layered portion formed only of the resin 120 may be included, so that the current flow may be partially cut off, so that the contact resistance and the electric conductivity may be further lowered.

The thickness of the first conductive continuous fiber bundle 110 may be, for example, from about 0.1 mm to about 0.2 mm and the width from about 1.0 mm to about 20.0 mm. By having the thickness and the width within the above range, the fuel cell separator can be more easily aligned in the one direction, and the fuel cell separator manufactured therefrom can realize excellent bending strength.

The average diameter of the first conductive continuous fibers as the filament may be about 7 占 퐉 to about 30 占 퐉. By having the diameter within the above range, the impregnated resin 120 can be easily impregnated, and the bending strength of the fuel cell separator can be realized at an excellent level.

The line density of the first conductive continuous fibers as the filament may be about 800 g / km to about 4,000 g / km. By having the linear density within the above range, the layer formed by the first conductive continuous fiber bundles 110 aligned in one direction can be appropriately included, so that the productivity can be improved, and the total weight can be formed at an appropriate level, have.

In particular, if it is less than about 800 g / km, the layer must be included too much, resulting in an increase in the production time, resulting in a decrease in productivity. In the case of more than about 4,000 g / km, There is a problem that it is difficult to achieve weight reduction due to increased weight.

The impregnated resin 120 may be a thermoplastic resin and the thermoplastic resin may be selected from the group consisting of polyethylene, polyprooylene, polyurethane, polyethyleneterephthalate, polybutylene terephthalate polybutylene terephthalate, polyurea, polyvinylchloride, polyvinylacetate, ethylenevinylacetate, melamine, phenol, polyphenylene sulfide, At least one selected from the group consisting of polyamide, polyimide, polybenzimidazole, polyetheretherketone, acryl, and combinations thereof.

Further, the impregnated resin 120 specifically includes polyamide, so that the bending strength can be further improved.

The weight ratio of the impregnated resin 120 to the first conductive continuous fiber bundle 110 may be, for example, from about 1:40 to about 1:99, and specifically from about 1:70 to about 1:90 . By having the weight ratio within the above range, the composite material 100 for a fuel cell separator can achieve excellent durability and excellent electrical conductivity at the same time.

The composite material 100 for the fuel cell separator may include, for example, about 1 to about 100 layers formed of the first conductive continuous fiber bundles 110 aligned in the one direction. The distance between the layers is appropriately adjusted to a level necessary for realizing a required level of durability and electrical conductivity of the composite material 100 for the fuel cell separator, so that the number of the fuel in the direction perpendicular to the layer The thickness of the composite material 100 for a battery separator plate can be appropriately adjusted.

The thickness (d _v) of the fuel cell separating panyong composite material 100 in a direction perpendicular to the layer may be about 0.12mm to about 22.0mm. The thickness d _v of the composite material 100 for the fuel cell separator in a direction perpendicular to the layer may be the width of the exposed surface of the end face of the first conductive continuous fiber bundle 110.

When the fuel cell separator is formed of the composite material 100 for the fuel cell separator by having the thickness within the above range, the longitudinal direction of the first conductive continuous fiber bundle 110 may be the same as the longitudinal direction of the fuel cell separator, The current flowing direction of the fuel cell separator and the longitudinal direction L of the first conductive continuous fiber bundle 110 are set to be equal to each other So that the flow of the current is made uniform, and at the same time, the disconnection is effectively prevented, so that a low contact resistance and excellent electric conductivity can be realized.

The width d _p of the composite material 100 for the fuel cell separator in a direction parallel to the layer and perpendicular to the longitudinal direction of the first conductive continuous fiber bundle 110 is about 25.0 mm to about 100.0 mm But is not limited thereto. The width d _p of the composite material 100 for the fuel cell separator in a direction parallel to the layer and in a direction perpendicular to the longitudinal direction of the first conductive continuous fiber bundle 110 is smaller than a width d _p of the first conductive continuous fiber bundle 110 110 may be the width of the exposed surface.

In one embodiment, the first conductive continuous fiber bundles 110 are uniformly aligned in one direction, and the plurality of layers may all be parallel so that the length of the first conductive continuous fiber bundles 110 (L) may be parallel to each other so that the composite material 100 for the fuel cell separator is formed so as to be equal to the flow direction of the current and the longitudinal direction L when the fuel cell separator is formed, And it is possible to prevent disconnection.

In the case of using short fibers, for example, needle punching or electrostatic flocking can be applied, the resin can be oriented in a certain direction. However, as a subsequent resin impregnating step, in the process of being dipped in a resin or molded by thermocompression, The current in the fuel cell separator flows unevenly and can be partially disconnected because it is difficult to maintain the aligned state in one direction. The length of such short fibers may be, for example, from about 2.0 mm to about 5.0 mm.

The composite material 100 for a fuel cell separator can be uniformly aligned in one direction more easily by using straight continuous fibers and can maintain a good level of orientation of fibers even in a subsequent resin impregnation step, As described above, in the case of the fuel cell separator, it is possible to uniformly flow the current and prevent the current from flowing out.

When the composite material 100 for at least one fuel cell separator is formed of a fuel cell separator, both end faces of the first conductive continuous fiber bundle 110 are separated from the upper surface and the lower surface of the fuel cell separator. Respectively. Accordingly, the current can easily flow through the both end surfaces, so that the contact resistance of the fuel cell separator plate can be further lowered, thereby realizing better electrical conductivity.

Referring to FIG. 1, the composite material 100 for a fuel cell separator includes two exposed surfaces of both end faces of the first conductive continuous fiber bundle 110 and a side surface S ₂ therebetween, When the composite material 100 for a plurality of fuel cell separators is formed as a fuel cell separator, the composite material 100 may be attached to the side S ₂ .

That is, after the lamination in one of one side surface (S ₂₎ of the fuel cell separating panyong composite material 100, one side surface (S ₂₎ and the other one of the fuel cell separating panyong composite material 100 of the contact with each other by way of hot pressing And can be formed by attaching and molding.

Accordingly, when a plurality of fuel cell separator composite members 100 are formed by fuel cell separator plates, the ends of the first conductive continuous fiber bundle 110 of the plurality of fuel cell separator composite members 100 are exposed the surface (S ₁₎ come together there is a pair of forming a plane, and the plane of the pair can be respectively formed in upper and lower surfaces of the fuel cell bipolar plate, a top surface and a bottom of the fuel cell bipolar plate The end face of the first conductive continuous fiber bundle 110 may be exposed.

In one embodiment, the longitudinal direction of the first conductive continuous fiber bundle 110 may be perpendicular to the upper surface and the lower surface of the fuel cell bipolar plate.

The flow direction of the current in the fuel cell separator and the longitudinal direction L of the first conductive continuous fiber bundle 110 are the same so that the current flows from the upper surface to the lower surface, The first conductive continuous fiber bundle 110 can be easily flowed along the first conductive continuous fiber bundle 110 so that the first conductive continuous fiber bundles 110 are aligned in one direction to uniformly flow the current, The fuel cell separator can realize a lower contact resistance and better electrical conductivity.

In one embodiment, the composite material 100 for the fuel cell separator may not include a conductive filler.

In order to satisfy the electric conductivity and the thermal conductivity required in a fuel cell separator, a step of additionally adding a large amount of conductive filler in addition to the conductive fiber must be additionally required, which complicates the process, consumes more time and costs, If such a conductive filler is contained in a large amount, there is a problem that moldability and workability are deteriorated.

As described above, the composite material 100 for a fuel cell separator has a structure in which the end faces of the first conductive continuous fiber bundles 110 are exposed on the upper and lower surfaces of the fuel cell separator, Can be formed so as to be the same as the flow direction of the current, so that it is possible to realize a low contact resistance and excellent electrical conductivity without including a separate conductive filler.

Accordingly, since the manufacturing process of the composite material 100 for the fuel cell separator is simplified, time and cost are reduced, productivity can be effectively improved, and at the same time, the molding processability of the composite material 100 for the fuel cell separator is further improved .

 Wherein the conductive filler is at least one selected from the group consisting of carbon powder, platelet graphite, spheroidal graphite, expanded graphite, carbon black, acetylene black, ketjen black, denka black, super P, activated carbon, carbon fiber, carbon nanotube, carbon nanofiber, Nanowires, carbon nanohorns, carbon nanorings, and the like, but are not limited thereto.

In one embodiment, the layer included in the composite 100 for the fuel cell separator may or may not further include a second conductive continuous fiber bundle aligned in a direction different from the one direction. The first conductive continuous fiber bundle 110 may be the same as described above except that the second conductive continuous fiber bundles are aligned in the different directions.

The second conductive continuous fiber bundle may be included in the form of a woven fabric that is woven crosswise to the first conductive continuous fiber bundles 110 or may be partially or wholly formed on the first conductive continuous fiber bundles 110 without being woven But the present invention is not limited thereto.

When the second conductive continuous fiber bundle is further included, the bending strength tends to be lowered. However, since the external impact can be absorbed more easily, for example, the impact strength and the like can be improved, Or not.

When the second conductive continuous fiber bundle is included in the form of a woven material, for example, the first conductive continuous fiber bundle 110 aligned in one direction is inclined and the second conductive continuous fiber bundle becomes a weft, But may be woven by sandwiching and combining the first conductive continuous fiber bundles 110, but is not limited thereto.

The woven fabric may be woven in a form including at least one selected from the group consisting of plain woven, twilled, water-woven, and combinations thereof, and the specific woven fabric may be selected according to the physical properties or applications to be implemented .

For example, when the second conductive continuous fiber bundle is included, the weight ratio of the impregnated resin 120 to the second conductive continuous fiber may be about 1:40 to about 1:99, and specifically about 1:70 To about 1: 90. By being included in the content within the above range, the electrical conductivity and the durability can be appropriately controlled to realize both of these properties at a good level at the same time.

In another embodiment of the present invention, the end faces of the first conductive continuous fiber bundle 110 are exposed on the upper surface and the lower surface of the composite material 100 for the fuel cell separator, Thereby providing a fuel cell separator plate 200. FIG. 2 schematically shows a perspective view of the fuel cell separator 200. The composite material 100 for the fuel cell separator is as described above in one embodiment.

The fuel cell separator 200 has a first conductive continuous fiber bundle 110 aligned in the first direction and a second conductive continuous fiber bundle 110 extending in the longitudinal direction of the bundle of first conductive continuous fibers 110 L is formed in the same direction as the current flow direction in the fuel cell separator 200, current can flow along the first conductive continuous fiber bundle 110, thereby making the current flow uniform, It is possible to effectively prevent the break of the flow.

As a result, the composite material 100 for a fuel cell separator is not formed of a metal material, so that it has excellent corrosion resistance and does not contain a large amount of conductive filler, thereby providing excellent processability, productivity and molding processability. At the same time, It is possible to realize a low contact resistance and excellent electric conductivity since the disconnection can be prevented while being more uniform.

Wherein the composite material for a fuel cell separator includes two surfaces of which both end faces of the first conductive continuous fiber bundle are exposed and side faces (S ₂ ) therebetween, The composite material 100 can be attached to the side surface S ₂ by thermocompression and molded.

That is, after the lamination in one of one side surface (S ₂₎ of the fuel cell separating panyong composite material 100, one side surface (S ₂₎ and the other one of the fuel cell separating panyong composite material 100 of the contact with each other by way of hot pressing And can be formed by attaching and molding. The ends of the first conductive continuous fiber bundles 110 of the composite material 100 for a plurality of fuel cell bipolar plates are exposed when the composite material 100 for a plurality of fuel cell divider plates is formed by the fuel cell separator plate 200, A pair of planes S ₁ may be gathered to form a pair of planes and the pair of planes may be formed as upper and lower surfaces of the fuel cell separator 200, The end surfaces of the first conductive continuous fiber bundles 110 may be exposed on the upper and lower surfaces of the plate 200.

In another embodiment, the length L of the first conductive continuous fiber bundle 110 may be perpendicular to the top and bottom surfaces of the fuel cell baffle plate 200, The longitudinal direction L of the fiber bundle 110 becomes the same as the flow direction of the current in the fuel cell separator 200, thereby realizing excellent electrical conductivity and low contact resistance.

The total thickness of the separator plate may be from about 0.1 mm to about 2.0 mm. By having the thickness within the above range, the separating performance for maintaining the insulation can be sufficiently realized without excessively increasing the size of the fuel cell or the unit cell including the separator. When the total thickness of the separator exceeds about 2.0 mm, it is not possible to achieve weight reduction and miniaturization of the separator which occupies the largest weight portion among the constituent parts of the fuel cell.

For example, the fuel cell separator 200 may have a contact resistance of about 20 m? Cm ² or less, specifically about 10 m? · Cm ² to about 20 m? · Cm ² , and a corrosion current density of, for example, , may be up to about 10μA / cm ^2, specifically, approximately 1.5μA / cm ² to about may be 10μA / cm ^2. By having the contact resistance within the above range, it is possible to realize an excellent electrical conductivity to further improve the energy efficiency of the fuel cell, and at the same time, by having the corrosion current density within the above range, the corrosion resistance is improved, and long durability can be realized.

Also, the electric conductivity of the fuel cell separator 200 may be about 100 S / cm to about 200 S / cm, thereby realizing excellent electrical properties and improving energy efficiency.

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In another embodiment of the present invention, there is provided a method of manufacturing the fuel cell bipolar plate, and schematically shows a process flow chart of the manufacturing method in Fig. Figs. 4 to 7 schematically show a schematic diagram for explaining each of the following steps included in the above manufacturing method. Fig.

The manufacturing method includes: forming a first conductive continuous fiber bundle sheet (S1); The first conductive continuous fiber bundle sheets are laminated and then impregnated with the impregnated resin and dried, or the first conductive continuous fiber bundle sheet and the impregnated resin film are alternately laminated, followed by thermocompression bonding, Forming a preliminary composite material (S2); Forming a composite material for a fuel cell separator by cutting the preliminary composite material perpendicularly to the longitudinal direction of the first conductive continuous fiber bundle at regular intervals within a range of about 0.1 mm to about 2.0 mm; And fabricating a fuel cell bipolar plate such that both end faces of the first conductive continuous fiber bundle are exposed to the upper and lower surfaces of the fuel cell bipolar plate by the composite material for the at least one fuel cell bipolar plate S4).

By the above-described manufacturing method, it is possible to manufacture the above-described fuel cell separator in the composite material for fuel cell separator and the above-described fuel cell separator in one embodiment, whereby the fuel cell separator has excellent processability, excellent productivity, Excellent corrosion resistance, low contact resistance and excellent electrical conductivity can be realized.

The composite material for the first conductive continuous fiber bundle, the impregnation resin, and the fuel cell separator is as described above in one embodiment.

Further, the thickness of the first conductive continuous fiber bundle sheet may be, for example, about 200 탆 to about 300 탆, and the impregnated resin film is a film formed of the impregnated resin, for example, But may be varied depending on the purpose and function of the invention, but is not limited thereto.

In the above manufacturing method, the first conductive continuous fiber bundle sheet can be formed by aligning the bundles of the first conductive continuous fiber bundles in one direction on a single plane, and specifically, the bundles of the first conductive continuous fiber bundles can be uniformly And may be formed as a sheet. Accordingly, the first conductive continuous fiber bundle sheet may include a first conductive continuous fiber bundle aligned in one direction.

Further, in the step of forming the first conductive continuous fiber bundle sheet, the first conductive continuous fiber bundle sheet may further include a second conductive continuous fiber bundle aligned in a direction different from the one direction, As shown in FIG. The second conductive continuous fiber bundle may be included in the form of a woven fabric that is interwoven with the first conductive continuous fiber bundle or may be partially or wholly adhered on the first conductive continuous fiber bundle without being woven But are not limited thereto. The second conductive continuous fiber bundle is as described above in one embodiment.

In the above manufacturing method, after impregnating and drying the impregnated resin after laminating the plurality of first conductive continuous fiber bundle sheets or alternately laminating the first conductive continuous fiber bundle sheet and the impregnated resin film, Compression can be performed to form a preliminary composite. When the first conductive continuous fiber bundle sheet and the impregnated resin film are alternately laminated, the impregnated resin film is impregnated into the first conductive continuous fiber bundle sheet by thermocompression, so that any one of them may be formed as an outermost layer And is not particularly limited.

As shown in FIG. 5, the preliminary composite material may be a composite material in which the plurality of first conductive continuous fiber bundle sheets are included in parallel with each other in the impregnation resin, and the composite material used for forming the composite material for the fuel cell separator . Specifically, the first conductive continuous fiber bundle sheet may be a single layer, and the plurality of layers may be included in parallel with each other in the infiltration resin.

The preliminary composite material may be formed by, for example, hot pressing at a temperature of about 100 째 C to about 300 째 C and performing a thermal compression at a pressure of about 10 kg / cm 2 to about 100 kg /

When the first conductive continuous fiber bundle sheet and the impregnated resin film are alternately laminated, the impregnated resin film is laminated on the upper, lower or upper and lower portions of the first conductive continuous fiber bundle sheet, and then heat and pressure are applied, The molten resin can be impregnated into the bundle of the first conductive continuous fibers.

Accordingly, in the preliminary composite, the first conductive continuous fiber bundle sheet is formed as one layer, and the plurality of layers may be all parallel with each other, so that the length of the first conductive continuous fiber bundle All directions can be parallel.

In the above manufacturing method, the composite material for a fuel cell separator may be formed by cutting the preliminary composite material perpendicularly to the longitudinal direction of the first conductive continuous fiber bundle at regular intervals within a range of about 0.1 mm to about 2.0 mm. That is, it is possible to use a composite material for a fuel cell separator, which is cut perpendicularly to the longitudinal direction of the first conductive continuous fiber bundle at equal intervals within a range of about 0.1 mm to about 2.0 mm, A pair of surfaces from which both end faces of the first conductive continuous fiber bundle are exposed may be gathered to form opposing surfaces of the fuel cell separator, that is, upper and lower surfaces.

In this manner, the length of the first conductive continuous fiber bundle included in the composite material for a fuel cell separator can be formed at a level of about 0.1 mm to about 2.0 mm by cutting at regular intervals within the above range. When the fuel cell separator is formed by the composite material for the fuel cell separator, the longitudinal direction of the first conductive continuous fiber bundle is formed to be perpendicular to the upper surface and the lower surface of the fuel cell separator So that current can flow along the bundle of the first conductive continuous fibers, so that the flow of the current is made uniform and the disconnection is prevented, so that excellent electrical conductivity and low contact resistance can be realized.

The fuel cell separator may be manufactured such that the end faces of the bundles of the first conductive continuous fiber bundle are respectively exposed to the upper and lower surfaces of the fuel cell separator plate by the composite material for the at least one fuel cell separator plate.

For example, if the size of the composite material for the fuel cell separator formed in accordance with the standard of the fuel cell separator to be implemented is used as the fuel cell separator plate as it is, So that the fuel cell separator can be manufactured. When the composite material for one fuel cell separator is formed by thermocompression bonding, for example, it can be carried out by hot pressing, and the temperature and pressure conditions at this time can be carried out by appropriately setting, and there is no particular limitation.

For example, when the size of the composite material for a fuel cell separator formed by cutting is smaller than the size of a fuel cell separator to be implemented, for example, when the thickness in a direction perpendicular to the layer is small, The fuel cell separator plate can be manufactured by attaching the composite material for fuel cell separator plates by thermocompression bonding.

1, the composite material for a fuel cell separator includes two surfaces, both end surfaces of which are exposed at both end faces of the first conductive continuous fiber bundle, and side surfaces therebetween, and a plurality of When the fuel cell separator plate composite member is formed of the fuel cell separator plate, it may be attached to the side surface.

That is, one side of the composite material for one fuel cell separator and one side of the composite material for the other fuel cell separator may be laminated in a manner in which they are in contact with each other, and then adhered and formed by thermocompression bonding.

Accordingly, when the composite material for a plurality of fuel cell divider plates is formed of a fuel cell divider plate, a pair of planar surfaces of the ends of the first conductive continuous fiber bundle of the composite material for the plurality of fuel cell divider plates are gathered to form a pair of planes And the pair of planes may be formed as the upper surface and the lower surface of the fuel cell separator, respectively.

The thermocompression bonding can be performed in all directions according to a method known in the art and can be applied so that the heat and pressure are suitably applied and adhered within a range that the physical properties of the composite material for a plurality of fuel cell separators are not significantly deformed , And is not particularly limited.

The fuel cell separator may be formed by, for example, hot pressing at a temperature of about 100 캜 to about 300 캜 and performing a thermal compression at a pressure of about 1 kg / cm 2 to about 10 kg / cm 2,

Specifically, the thermal compression to form the composite material for the fuel cell separator may be performed at a temperature equal to or higher than that of the case of the thermal compression forming the fuel cell separator. Or the same or higher pressure; Under conditions.

Hereinafter, specific embodiments of the present invention will be described. However, the embodiments described below are only intended to illustrate or explain the present invention, and the present invention should not be limited thereto.

Example

Example  One

A first conductive carbon continuous fiber bundle having a length of 250 mm formed of 3,000 strands of the first conductive carbon continuous fibers having an average diameter of 7 μm and a line density of 1650 g / km was aligned in one direction on a single plane to form a first conductive carbon continuous fiber A bundle sheet was prepared, and the size of the first conductive carbon continuous fiber bundle sheet was 250 x 250 x 0.3 mm.

Thereafter, 20 sheets of the first conductive carbon continuous fiber bundle sheet aligned in one direction and twenty 250 x 250 x 0.1 mm polypropylene resin films were alternately laminated, followed by thermocompression at a temperature of 220 캜 and a pressure of 40 kg / cm 2 Thereby forming a composite material for a fuel cell separator.

Next, the composite material for the fuel cell separator was cut perpendicularly to the longitudinal direction of the first conductive carbon continuous fiber bundle at intervals of 2.0 mm, and the composite material for the fuel cell separator was cut in both ends of the first conductive carbon continuous fiber bundle. The cross section includes two exposed surfaces and the side surface between them.

Specifically, the length of the first conductive carbon continuous fiber bundle contained in the composite material for the cut fuel cell separator was 2.0 mm, and the weight ratio of the polypropylene resin to the first conductive continuous fiber bundle was 1:80.

Then, the composite material for the five cut fuel cell separators was laminated in such a manner that the respective side surfaces were in contact with each other, and then hot pressed (Carver, Auto 30ton) at 160 ° C and a pressure of 5 kg / To prepare a fuel cell separator.

The ends of the first conductive carbon continuous fiber bundle are exposed on the upper surface and the lower surface of the fuel cell separator, and the longitudinal direction of the bundle of the first conductive carbon continuous fibers is the upper surface of the fuel cell separator. And a direction perpendicular to the lower surface, which was the same as the flow direction of the current, and the total thickness of the fuel cell separator was 2.0 mm.

Example 2 (further comprising a second conductive continuous fiber bundle)

A second conductive carbon continuous fiber bundle having a length of 250 mm formed of 3,000 strands of the second conductive carbon continuous fibers having an average diameter of 7 mu m and a line density of 1650 g / km was interwoven with the first conductive carbon continuous fiber bundle, The fuel cell separator was fabricated in the same manner as in Example 1 except that the first conductive carbon continuous fiber bundle sheet was further provided with a second conductive carbon continuous fiber bundle aligned in a direction different from the one direction.

Specifically, the length of the second conductive carbon continuous fiber bundle included in the cut material for the fuel cell separator was 250 mm, the weight ratio of the polypropylene resin to the second conductive carbon continuous fiber bundle was 1:80, Was 2.0 mm.

Comparative Example 1 (including a polymer resin and an electrically conductive filler and containing a small amount of electrically conductive filler)

50% by weight of a polypropylene resin and 50% by weight of carbon black as a conductive filler were mixed and stirred to prepare a fuel cell separator by injection molding.

The total thickness of the fuel cell separator was 2.0 mm.

Comparative Example 2 (including a polymer resin and an electrically conductive filler, and an electrically conductive filler in an appropriate amount)

20% by weight of a polypropylene resin; And carbon black as a conductive filler and carbon nanotubes were mixed and stirred in a total amount of 80% by weight of the carbon black and the carbon nanotubes as a conductive filler, to prepare a fuel cell separator.

The total thickness of the fuel cell separator was 2.0 mm.

Comparative Example 3 (including short fibers)

A short carbon short fiber having an average diameter of 7 mu m and a length of 2 mm was formed by using electrostatic flocking technology to form a carbon mono short fiber sheet oriented substantially in one direction and then a liquid polypropylene resin was infiltrated into the short carbon fiber sheet, A composite material for a battery separator was prepared, and the weight ratio of the polypropylene resin to the carbon short fibers was 1:50.

Subsequently, the composite material was formed by thermocompression at 160 ° C and a pressure of 5 kg / cm 2 using a hot press (Carver, Auto 30ton) to produce a fuel cell separator. The total thickness Was 2.0 mm.

Comparative Example 4 (when the longitudinal direction of the carbon fibers was parallel to the upper and lower surfaces of the fuel cell separator)

A continuous carbon fiber bundle of 250 mm in length formed by 3,000 strands of the first conductive continuous fiber having an average diameter of 7 μm and a line density of 1650 g / km was weighed so as to cross each other with warp and weft to form a carbon continuous fiber sheet in the form of a woven material The size of the carbon continuous fiber sheet was 250 x 250 x 0.025 mm, and the intervals between the warp yarns and the weft yarns were the same.

Subsequently, three carbon continuous fiber sheets and two 250 x 250 x 0.025 mm polypropylene resin films were alternately laminated, followed by thermocompression at a pressure of 40 kg / cm 2 and a temperature of 220 캜 to prepare a fuel cell separator , And the total thickness of the fuel cell separator was 2.0 mm.

Considering the general standard of the fuel cell separator, since the longitudinal direction of the carbon continuous fibers is parallel to the upper and lower surfaces of the fuel cell separator plate, The direction of current flow was different. In addition, there was a portion of the layer containing only polypropylene resin between the sheets of the carbon fibers. 4 is a schematic perspective view of the fuel cell separator according to Comparative Example 4. As shown in FIG.

Experimental Example

The physical properties of the fuel cell bipolar plates according to Examples 1 and 2 and Comparative Example 1-4 were evaluated and are shown in Table 1 below

Assessment Methods

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(Electrical conductivity and contact resistance)

Measuring method: Measured using a 4-probe method by a Keithley / 6220 / 2182A, USA instrument.

Further, in the contact resistance measuring instrument, measurement was carried out by providing a pressure of 100 N / cm ² using a compression holding tester (Instron, 5569A 5566).

(Molding processability).

Measurement method: Whether or not grooves or cracks occurred on the surface of the fuel cell separator according to Examples 1 and 2 and Comparative Example 1-4 was visually observed, and the grooves and cracks did not occur, Quot ;, "? &Quot;, the case where the grooves or cracks occurred and the forming processability was inferior was denoted by " X ", and the preferable case was denoted by "DELTA ".

(The grooves or cracks were observed to have a depth of at least 1 mm.)

Electrical conductivity
(S / cm) Contact resistance
(m? cm ² ) Moldability Example 1 100 15 ○ Example 2 100 20 ○ Comparative Example 1 0.01 1000 ○ Comparative Example 2 0.02 200 X Comparative Example 3 2 100 △ Comparative Example 4 90 40 ○

It was confirmed that the fuel cell bipolar plates according to Examples 1 and 2 were both excellent in electrical conductivity and contact resistance and excellent in moldability.

On the other hand, it was confirmed that the fuel cell separator according to Comparative Examples 1 to 4 had a significantly low electrical conductivity and a remarkably high contact resistance, which was inferior in performance. In the case of Comparative Example 2, it was clearly confirmed that the moldability was also inferior.

100: Composite for fuel cell separator
110: first conductive continuous fiber bundle aligned in one direction
120: impregnated resin
S ₁ : a pair of exposed faces of the end faces of the first conductive continuous fiber bundle
S ₂ : a side surface between a pair of exposed surfaces of the end faces of the first conductive continuous fiber bundle
L: length of the first conductive continuous fiber bundle
200: Fuel cell separator plate
d _v : thickness of composite material for fuel cell separator in a direction perpendicular to the layer
d _p : the width of the composite material for the fuel cell baffle in a direction parallel to the layer and perpendicular to the longitudinal direction of the first conductive continuous fiber bundle

Claims (22)

A first conductive continuous fiber bundle and an impregnated resin aligned in one direction, wherein both end faces of the first conductive continuous fiber bundle include two exposed faces and side faces therebetween, the side faces being attached to each other Composites for fuel cell separators; And
The upper surface contacting the gas diffusion layer and the membrane electrode assembly in the fuel cell, the upper surface being in contact with the gas diffusion layer and the membrane electrode assembly in the fuel cell, A lower surface
Fuel cell separator.
delete delete delete delete The method according to claim 1,
A conductive filler is not included
Fuel cell separator.
The method according to claim 1,
Wherein the length of the first conductive continuous fiber bundle is 0.1 mm to 2.0 mm
Fuel cell separator.
The method according to claim 1,
Wherein the first conductive continuous fiber bundle is formed by bundling an average of 1,000 to 48,000 strands of the first conductive continuous fibers as the filament filaments,
Wherein the first conductive continuous fiber bundle has a thickness of 0.1 mm to 0.2 mm and a width of 1.0 mm to 20.0 mm
Fuel cell separator.
The method according to claim 1,
Wherein the first conductive continuous fibers have a linear density of 800 g / km to 4,000 g / km
Fuel cell separator.
The method according to claim 1,
Wherein the weight ratio of the impregnating resin to the first conductive continuous fiber bundle is from 1:40 to 1:99
Fuel cell separator.
delete The method according to claim 1,
Wherein the composite material for the fuel cell separator comprises a plurality of layers including the first conductive continuous fiber bundle, wherein the thickness in the direction perpendicular to the layer is from 0.12 mm to 22.0 mm
Fuel cell separator.
The method according to claim 1,
Wherein the composite material for the fuel cell separator includes a plurality of layers including the first conductive continuous fiber bundle and a width parallel to the layer and in a direction perpendicular to the longitudinal direction of the first conductive continuous fiber bundle is 25.0 mm to 100.0 mm
Fuel cell separator.
The method according to claim 1,
Wherein the first conductive continuous fiber comprises an organic fiber, an inorganic fiber, or all of them, wherein the surface of the fiber is coated with a conductive filler, or the conductive filler is dispersed in the fiber,
Fuel cell separator.
The method according to claim 1,
Wherein the composite material for the fuel cell separator further comprises a second conductive continuous fiber bundle including a plurality of layers including the first conductive continuous fiber bundle and the layer being aligned in a direction different from the one direction,
Wherein the first conductive continuous fiber bundle and the second conductive continuous fiber bundle are in the form of a woven
Fuel cell separator.
delete delete delete The method according to claim 1,
Wherein the total thickness of the fuel cell separator plate is 0.1 mm to 2.0 mm
Fuel cell separator.
The method according to claim 1,
And the contact resistance is less than 20mΩ · cm ² measured at a pressure of 100N / cm ^2,
The electrical conductivity is in the range of 100 S / cm to 200 S / cm
Fuel cell separator.
delete Forming a first conductive continuous fiber bundle sheet;
A plurality of the first conductive continuous fiber bundle sheets are laminated, and the impregnated resin is immersed and dried, or alternatively, the first conductive continuous fiber bundle sheet and the impregnated resin film are alternately laminated, Forming a preliminary composite;
Forming the composite material for a fuel cell separator by cutting the preliminary composite material perpendicularly to the longitudinal direction of the first conductive continuous fiber bundle at regular intervals within a range of 0.1 mm to 2.0 mm; And
Wherein the end faces of the first conductive continuous fiber bundle are respectively exposed on the upper and lower surfaces of the fuel cell separator using the composite material for the fuel cell separator and the end faces of both ends of the first conductive continuous fiber bundle are exposed, Preparing a fuel cell bipolar plate such that side faces of each of the composite materials for bipolar plates that are not exposed are thermocompression bonded;
The method of manufacturing a fuel cell bipolar plate according to claim 1,

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