KR101698583B1 - Separator for fuel cell, method for manufacturing the same and fuel cell comprising the same - Google Patents

Abstract

Disclosed is a separator for a fuel cell and a fuel cell including the separator. The separator for a fuel cell includes an inner support and a sheath formed around the outer periphery of the inner support and including at least one outer surface, Wherein the inner support comprises a conductive structure selected from the group consisting of a conductive polymer, a conductive inorganic material, and combinations thereof, the outer material including a conductive filler and a polymeric resin, wherein the inner material has a low thickness and excellent mechanical strength and gas tightness Lt; / RTI >

Description

Technical Field [0001] The present invention relates to a separator for a fuel cell, a method of manufacturing the same, and a fuel cell including the separator,

The present invention relates to a separator for a fuel cell, which can exhibit excellent mechanical strength and gas tightness while being thin, a method for producing the same, and a fuel cell including the same.

Fuel cells are attracting attention as one of the renewable energy sources as the importance of alternative energy due to depletion of energy resources is highlighted. In particular, fuel cells have been intensively studied due to their advantages of high efficiency and environmental friendliness.

The stack, which is a main part of the fuel cell system, is a set of stacked unit cells, and one cell is composed of a membrane electrode assembly (MEA) and a bipolar plate or separator. In the case of separator plates, the largest quantity is used in manufacturing the stack, and the structure of the stack is determined according to the shape of the separator plate.

The separator performs various functions such as supplying hydrogen and oxygen to the cathode and the anode respectively, preventing mixing of the supplied gases, transferring the generated electrons during the electrode reaction and discharging the water generated in the anode to the outside . Accordingly, the separator plate should have excellent electron conductivity for facilitating the movement of electrons, and have appropriate surface characteristics so that the water generated from the anode can be discharged smoothly. Further, in order to prevent mixing of the gas supplied to the cathode and the anode, it is required to have an excellent gas tightness and have proper corrosion resistance and strength characteristics according to the operating environment and operating conditions of the fuel cell. In addition, it should be thin and easy to process in order to access various fields such as home, automobile, and portable.

The material of the fuel cell separator that is currently being developed and used is a composite material of graphite, graphite and resin, or a metal material such as stainless steel or aluminum. However, in the case of producing a separator using graphite, there is a problem in that not only the flow cost of machining is high but also the time required for machining is long and the productivity is very low. In addition, when a separator of a metal base is manufactured, there is a disadvantage that it is easy to corrode while having good processability and dimensional accuracy. In addition, in the case of producing a separator using a composite material of graphite and resin, the above problems can be solved. However, it is difficult to store the material manufacturing environment and material, the dimensional precision of the product is low, It is not easy. In addition, when the composite material of graphite and resin is used as a thin plate, it is possible to reduce the volume of the fuel cell stack. Therefore, it is easy to access various fields such as home use, automobile, and portable. However, The bending strength and gas tightness are lowered.

Korean Patent Publication No. 2012-0128172 (published on November 27, 2012) Korean Patent Publication No. 2012-0093701 (published on August 23, 2012)

An object of the present invention is to provide a separator for a fuel cell and a method of manufacturing the same, which can exhibit excellent mechanical strength and gas tightness while being thin.

It is still another object of the present invention to provide a fuel cell including the separator for a fuel cell, which exhibits improved battery characteristics.

According to an aspect of the present invention, there is provided a fuel cell separator comprising an inner support and a sheath surrounding the outer periphery of the inner support, the outer sheath including at least one outer surface of the outer sheath, The inner support includes a conductive structure selected from the group consisting of a conductive polymer, a conductive inorganic material, and a combination thereof, and the outer material includes a conductive filler and a polymer resin.

In the separator for a fuel cell, the conductive polymer may be selected from the group consisting of poly (3,4-ethylenedioxythiophene) -poly (4-styrenesulfonate) (PEDOT: PSS), polypyrrole, polythiophene, Polyparaphenylene, and mixtures thereof. The term " polyparaphenylene "

The conductive inorganic material may be one selected from the group consisting of doped indium oxide, antimony doped tin oxide, antimony doped zinc oxide, tin oxide, zinc oxide, graphene, carbon nanotube, graphite and mixtures thereof .

The conductive structure may be a single-layer structure including at least one of a conductive polymer and a conductive inorganic material, or may be a multi-layer structure of two or more layers.

The conductive filler may be at least one selected from the group consisting of carbon powder, graphite powder, carbon black, acetylene black, ketjen black, denka black, super P, activated carbon, carbon nanotube, carbon nanofiber, carbon nanowire, And mixtures thereof.

In addition, the conductive filler may have an average particle diameter of 1 to 200 mu m.

The conductive filler may be included in an amount of 500 to 2500 parts by weight based on 100 parts by weight of the polymer resin.

The polymer resin may be a thermosetting resin or a thermoplastic resin.

The separator for a fuel cell may have a flexural strength of 50 MPa to 120 MPa, a density of 0.8 g / mL to 2.2 g / mL, and an electrical conductivity of 80 S / cm to 250 S / cm.

The separator for fuel cells may have a gas permeability of 2 X 10 ^-6 cm ³ / cm ² sec or less at a thickness of 0.8 mm to 1.5 mm.

According to another aspect of the present invention, there is provided a method of manufacturing a separator for a fuel cell, comprising: preparing a composite material for forming a shell material by mixing a conductive filler and a polymer resin; Wherein the inner support comprises a conductive structure selected from the group consisting of a conductive polymer, a conductive inorganic material, and combinations thereof.

The fuel cell according to another embodiment of the present invention includes the separator for the fuel cell.

Hereinafter, the present invention will be described in more detail.

According to another aspect of the present invention, there is provided a separation plate for a fuel cell,

An inner support, and

And a cover member which is formed to surround the outside of the inner support body and includes a flow path on at least one outer side surface,

Wherein the inner support comprises a conductive structure selected from the group consisting of a conductive polymer, a conductive inorganic material, and combinations thereof,

The sheathing material includes a conductive filler and a polymer resin.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic structural view of a separator for a fuel cell according to an embodiment of the present invention, wherein FIG. 1 (a) is a plan view of an inner support positioned on a lower shell material, . FIG. 1 is an illustration for illustrating the present invention, but the present invention is not limited thereto.

1, the separator plate 100 for a fuel cell according to the present invention includes an inner support body 10 and a shell material 20 surrounding the outer periphery of the inner support body.

The inner support 10 exhibits conductivity together with its supporting function. Specifically, the inner support 10 may include a conductive structure selected from the group consisting of a conductive polymer, a conductive inorganic material, and a combination thereof.

The conductive polymer may specifically be a poly (3,4-ethylenedioxythiophene) -poly (4-styrenesulfonate) (PEDOT: PSS), a polypyrrole, a polythiophene, a polyparaphenylene ), But the present invention is not limited thereto. It is also possible to use one of the conductive polymers described above, or a mixture of two or more thereof.

The conductive inorganic material may include tin-doped indium oxide (ITO), antimony-doped tin oxide (ATO), antimony-doped zinc oxide Conductive metal oxides such as AZO, tin oxide (SnO2) or zinc oxide (ZnO2); Or a carbon-based material such as graphene, carbon nano tube (CNT), or graphite.

The conductive structure may be a film or a sheet.

In addition, the conductive structure may be a single layer structure including at least one of the conductive polymer and the conductive inorganic material, or a multi-layer structure of two or more layers.

The combination of the conductive polymer and the conductive inorganic material may be a combination of the conductive polymer and the conductive inorganic material dispersed in the conductive polymer, the case where the conductive polymer is coated on the conductive inorganic material, and the single conductive polymer containing at least one of the conductive polymer and the conductive inorganic material. And a case where two or more layers are stacked.

When the conductive polymer and the conductive inorganic material are included in combination, it is preferable that the conductive inorganic material is included in an amount of 70 to 120 parts by weight based on 100 parts by weight of the conductive polymer, taking into account the support strength and conductivity of the inner support. If the content of the conductive inorganic material is less than 70 parts by weight, the mechanical strength characteristics may be deteriorated. If the content of the conductive inorganic material is more than 120 parts by weight, it is not easy to produce the film or sheet.

The inner support is preferably adjusted to have a thickness sufficient to exhibit a sufficient support effect in consideration of the total thickness of the separator and the kind of the outer cover material. Specifically, the thickness of the inner support is preferably in the range of 0.1 mm to 0.5 mm, To 70 MPa.

On the other hand, the outer cover member 20 is formed to surround the inner support member in contact with the outer surface of the inner support member 10 as described above.

The shell material 20 generally functions as a separator of a fuel cell, and includes a flow path 20a formed so that gas or liquid can flow through at least one outer surface. The shell member 20 may further include a plurality of manifolds 20b serving as holes for supplying hydrogen and oxygen or a cooling water passage (not shown) for maintaining the internal temperature during operation of the fuel cell have. When the manifold is formed, it is preferable that the flow path is formed by connecting any two arbitrarily selected ones of the manifolds so that gas or liquid flowing from the manifold can flow

The shell material 20 includes a conductive filler and a polymer resin.

The conductive filler may specifically be selected from the group consisting of carbon powder, graphite powder, carbon black, acetylene black, ketjen black, denka black, super P, activated carbon, carbon nanotube, carbon nanofiber, carbon nanowire, carbon nanohorn, And either one of them alone or a mixture of two or more thereof may be used. Of these, graphite powder may be more preferable in terms of reinforcing property and workability. The graphite powder may be natural graphite or synthetic graphite, and the synthetic graphite may be spherical or expanded graphite.

The shape of the conductive filler is not particularly limited, such as a particle shape, a plate shape, and a scaly shape, but may preferably be particles having an average particle diameter of 1 to 200 탆. When the average particle diameter of the conductive filler is less than 1 mu m, there is a concern that the conductive fillers may aggregate. If the average particle size of the conductive filler exceeds 200 mu m, there is a fear that the molding and gas tightness are lowered.

The conductive filler may be contained in an amount of 500 to 2,500 parts by weight based on 100 parts by weight of the polymer resin. If the content of the conductive filler is less than 500 parts by weight, the effect of improving the conductivity and mechanical properties of the conductive filler is insufficient. When the amount exceeds 2500 parts by weight, the fluidity of the conductive filler is low. Simultaneous molding of the folds is difficult. As the size of the separating plate to be formed becomes larger, the thickness variation becomes larger, and the strength and gas tightness may be lowered. The conductive filler may be included in an amount of 700 to 2000 parts by weight based on 100 parts by weight of the polymer resin, considering the reinforcing property, the conductivity, and the gas tightness improvement effect of the conductive filler.

The polymer resin can be used without particular limitation as long as it is usually used in the production of separator plates for fuel cells. Specifically, a thermosetting resin, a thermoplastic resin, an engineering plastic, or the like can be used.

Specifically, the thermosetting resin may be a phenol resin, an epoxy resin, a benzoxazine resin, a melamine resin, a polyurethane resin, a urea resin, an alkyd resin, a polyimide resin, or the like. The thermoplastic resin may be a polyalkylene (for example, polypropylene (PP), polyethylene (PE) or the like), a fluoropolymer (for example, polyvinylidene fluoride (PVDF) ), Acrylic polymers (for example, polymethyl methacrylate (PMMA) and the like), polycarbonate, polyphenylene sulfide, polyether ether ketone, or poly Polyether sulfone, and the like. The engineering plastic may be a liquid crystal polymer, a liquid crystal rubber (LCP), or the like.

Among the above-mentioned polymer resins, benzooxazine-based resins having low viscosity and water absorption ratio and excellent thermal stability and mechanical properties may be preferable. Specific examples thereof include bisphenol A benzoxazine, bisphenol F benzoxazine, Phenolphthalein benzoxazine, thiodiphenol benzoxazine, dicyclopentadiene benzoxazine, and the like.

The outer cover material may further include an additive which is usually used in the production of a separator such as an inner mold release agent, a curing agent, a curing accelerator, or a water reducing agent for the purpose of enhancing the physical properties of the outer cover material and improving the ease of the production process.

Specifically, when a thermosetting resin is used as the polymer resin, it may further comprise a curing agent. The curing agent is not particularly limited as long as it is usually used for curing a thermosetting resin. Specific examples thereof include an epoxy compound, an amine compound, a diamine compound, a polyamine compound, a polyamide compound or a phenol resin. . In particular, when the benzoxazine-based resin is used, an epoxy compound may be preferably used as the curing agent. Among the epoxy compounds, a cycloaliphatic epoxy resin or a cresol novolac epoxy resin Lt; / RTI >

At this time, the addition amount of the curing agent is preferably 30 to 70 parts by weight based on 100 parts by weight of the polymer resin. When the content of the curing agent is less than 30 parts by weight, unreacted thermosetting resin may remain. When the content of the curing agent exceeds 70 parts by weight, a part of the curing agent may be unreacted.

Further, in order to shorten the curing time, the curing accelerator may be further added together with the curing agent. As the curing accelerator, a basic compound such as triphenylphosphine (TPP) diaminodiphenylsulfone (DDS), a tertiary amine, an imidazole compound, an epoxy compound or a phenol compound may be used.

The addition amount of the curing accelerator is preferably 0.5 to 8 parts by weight based on 100 parts by weight of the thermosetting resin. If the content of the curing accelerator is less than 0.5 parts by weight, the working time is long, which is easy for the work but the curing speed is slow, which is not preferable because the molding time is long. When the content is more than 8 parts by weight, the curing speed is shortened, not.

When the mixture of the polymer resin and the conductive filler further comprises a curing agent and a curing accelerator as described above, it is preferable to mix the polymer resin, the curing agent and the curing accelerator first and then to mix the conductive filler. In this case, Prior to mixing, it may be desirable to optionally further perform a milling process on the mixture of the polymer resin, the curing agent, and the curing accelerator. By controlling the particle size of the polymer resin and the curing agent to be the same level as the particle size of the conductive filler through the pulverization process, more homogeneous mixing is possible and a quick curing reaction during molding can be induced.

The separator for a fuel cell having the above structure may further include a step of mixing a conductive filler, a polymer resin and optionally other additives to prepare a composite material for forming a sheathing material, And then molding it.

For example, when a separator is manufactured using a mold, a composite material for forming a casing material including a conductive filler, a polymer resin, and optionally an additive is prepared. Placing a part of the composition for forming a covering material, the inner supporting body, and the remaining composition for forming a covering material sequentially on a mold for forming a separator of a fuel cell, followed by press molding . ≪ / RTI >

The composite material for forming the outer cover material may be prepared by mixing the polymer resin, the curing agent, the conductive filler, and the curing accelerator within the screw and then extruding the mixture into a pellet or a sheet.

Next, a composite plate for a fuel cell is manufactured by molding the composite material by a conventional method. The molding process may be carried out according to a conventional method, preferably at a temperature of 130 to 170 ° C. and a pressure of 300 to 600 tons. When the temperature and pressure during molding are out of the above ranges, it is not preferable for molding and curing. The flow channel may be simultaneously formed in the separator for fuel cells by the molding process.

The separator for a fuel cell manufactured by the above-described production method can exhibit excellent mechanical strength and gas tightness while being thin.

Specifically, the separator for a fuel cell may have a flexural strength of 50 MPa to 120 MPa, a density of 0.8 g / mL to 2.2 g / mL, and an electrical conductivity of 80 S / cm to 250 S / cm. The separator for a fuel cell may have a gas permeability of 2 X 10 ^-6 cm ³ / cm ² sec or less in a thickness range of 0.8 mm to 1.5 m. According to another aspect of the present invention, there is provided a fuel cell including the separator for a fuel cell.

In detail, the fuel cell includes a stack for generating electricity through an electrochemical reaction between a fuel and an oxidant, a fuel supply unit for supplying fuel to the electricity generation unit, and an oxidant supply unit for supplying an oxidant to the electricity generation unit, The stack includes a membrane-electrode assembly including an anode electrode and a cathode electrode facing each other, and a polymer electrolyte membrane disposed between the anode electrode and the cathode electrode, and a separator for fuel cells located on both sides of the membrane- And at least one unit cell including at least one unit cell.

Since each constituent part of the fuel cell is based on the configuration of a typical fuel cell, detailed description thereof will be omitted.

The fuel cell may be any one of a polymer electrolyte fuel cell (PEMFC), a direct methanol fuel cell (DMFC), a high temperature polymer electrolyte fuel cell, or a phosphoric acid fuel cell (PAFC) It is not.

The separator plate for a fuel cell according to the present invention can exhibit excellent mechanical strength and gas tightness while being thin. As a result, the battery characteristics can be further improved when applied to a fuel cell.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic structural view of a separator for a fuel cell according to an embodiment of the present invention, wherein FIG. 1 (a) is a plan view of an inner support positioned on a lower shell material, .
FIG. 2 is a graph showing flexural strengths of the separator for a fuel cell manufactured in the above-described embodiment and comparative example.
3 is a graph showing the density of the separator for fuel cells manufactured in Examples and Comparative Examples.
4 is a graph showing the average electric conductivity of the separator for fuel cells manufactured in Examples and Comparative Examples.
5 is a graph showing gas permeabilities of the separator plates for fuel cells manufactured in Examples and Comparative Examples.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

 [ Example : Manufacture of separation plate for fuel cell]

 An inner support was prepared using ITO film having a thickness of 130 mu m with polyethylene naphthalate (PEN) as a base material.

85 parts by weight of graphite, 9 parts by weight of epoxy resin, 6 parts by weight of curing agent, 6.7 phr of TPP as a curing accelerator and 5.6 phr of carnauba wax as an internal mold release agent were mixed Thereby preparing a composition for forming a coat on a powder. At this time, the graphite powder used was a plate-like natural graphite having an average particle size of 50 탆.

After 50% of the composition for covering material prepared above was put into a mold for a fuel cell separator having a flow path, an inner supporting body was placed thereon, and a composition for forming outer covering material was put on the inner supporting body. (Thickness: 1 mm) was manufactured by press molding.

[ Comparative Example : Manufacture of separation plate for fuel cell]

A separator plate (1 mm) for fuel cells was produced in the same manner as above except that the inner support was not used.

[ Test Example : Evaluation of characteristics of separator for fuel cell]

The bending strength, density, electrical conductivity and gas permeability of each of the separators for fuel cells prepared in Examples and Comparative Examples were measured.

1) Flexural strength

ASTM D790, and the measurement results are shown in FIG.

As shown in Fig. 2, it was found that the flexural strength of the example was higher than that of the comparative example.

2) Density

The densities of the separators for fuel cells prepared in the above Examples and Comparative Examples were measured. The results are shown in Fig.

As shown in FIG. 3, it was confirmed that the separators of Examples and Comparative Examples had low density values, which is a favorable condition for thinning.

3) Electrical Conductivity

The average electrical conductivity was evaluated using the resistance values measured by a 4-point probe. The results are shown in Fig.

As shown in FIG. 4, it can be seen that the examples and the comparative examples showed the values of the greatest values and satisfied the values of 100 S / cm or more, which is the required characteristic of the separator plate.

4) Gas permeability

The gas permeability was measured according to ASTM D1434, and the results are shown in Fig.

As shown in FIG. 5, both of the separators had lower values than the required gas tightness of 2.00E-06 of the separator disclosed in the DOE, but the results of the examples were more excellent.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, Of the right.

10 inner support
20 sheath material
100 separator plate

Claims (12)

An inner support comprising a multilayer structure comprising a conductive polymer and a conductive inorganic material, and
And a cover member which is formed to surround the outside of the inner support body and includes a flow path on at least one outer side surface,
The conductive polymer may be at least one selected from the group consisting of poly (3,4-ethylenedioxythiophene) -poly (4-styrenesulfonate) (PEDOT: PSS), polypyrrole, polythiophene, polyparaphenylene, A mixture thereof, and a mixture thereof.
Wherein the conductive inorganic material is selected from the group consisting of tin-doped indium oxide (ITO), antimony-doped tin oxide, antimony-doped zinc oxide, tin oxide, zinc oxide, graphene, carbon nanotubes, graphite, Which is selected,
Wherein the sheathing material comprises a conductive filler and a polymer resin. delete delete delete The method according to claim 1,
The conductive filler may be at least one selected from the group consisting of carbon powder, graphite powder, carbon black, acetylene black, ketjen black, denka black, super P, activated carbon, carbon nanotube, carbon nanofiber, carbon nanowire, carbon nanohorn, And mixtures thereof. The method according to claim 1,
Wherein the conductive filler has an average particle diameter of 1 to 200 mu m. The method according to claim 1,
Wherein the conductive filler is contained in an amount of 500 to 2500 parts by weight based on 100 parts by weight of the polymer resin. The method according to claim 1,
Wherein the polymer resin is a thermosetting resin or a thermoplastic resin. The method according to claim 1,
A bending strength of 50 to 120 MPa, a density of 0.8 to 2.2 g / mL, and an electrical conductivity of 80 to 250 S / cm. The method according to claim 1,
A separator for a fuel cell having a gas permeability of 2 X 10 ^-6 cm ³ / cm ² sec or less in a thickness of 0.8 to 1.5 mm. A step of mixing a conductive filler and a polymer resin to prepare a composite material for forming a sheathing material, and
And inserting an inner support between the composite materials for sheathing and then molding the composite material,
Wherein the inner support comprises a multilayer structure comprising a conductive polymer and a conductive inorganic material,
The conductive polymer may be at least one selected from the group consisting of poly (3,4-ethylenedioxythiophene) -poly (4-styrenesulfonate) (PEDOT: PSS), polypyrrole, polythiophene, polyparaphenylene, A mixture thereof, and a mixture thereof.
Wherein the conductive inorganic material is selected from the group consisting of tin-doped indium oxide (ITO), antimony-doped tin oxide, antimony-doped zinc oxide, tin oxide, zinc oxide, graphene, carbon nanotubes, graphite, Which is selected,
Wherein the sheathing material comprises a conductive filler and a polymer resin. A fuel cell comprising the separator plate for a fuel cell according to claim 1.

Images