KR101871022B1 - Bipolar plate of fuel cell and manufacturing method of the same - Google Patents

Abstract

The present invention relates to a polymeric foam base material comprising a plurality of pores; And a plating layer formed on the outer surface and the pore surface of the polymer foam base material, and a method for manufacturing the same.

Description

TECHNICAL FIELD [0001] The present invention relates to a separator for a fuel cell,

The present invention relates to a separator plate for a fuel cell and a method of manufacturing the same.

A fuel cell stack (Stack) is a power generation component that generates electrical energy by electrochemically reacting hydrogen and oxygen among various components of a fuel cell system. Such a fuel cell stack has a unit cell as a minimum unit for generating electric energy, and has a configuration in which several or several such unit cells are stacked in series.

The unit cells are composed of membrane electrode assemblies (MEAs) and separators for fuel cells which are in contact with both surfaces of the membrane electrode assembly. The membrane electrode assembly has a polymer electrolyte membrane selectively passing only hydrogen ions, and an anode electrode and a cathode electrode are bonded to both sides of the polymer electrolyte membrane.

The separator for fuel cell serves to collect the current generated in the unit cell, serves as a separator for maintaining insulation, and discharges water generated by supplying gas (hydrogen, oxygen) to the gas diffusion layer. Such a separator for fuel cells should be stable in the oxidizing and reducing atmosphere of the anode electrode and the cathode electrode, be capable of preventing gas mixing, and have sufficient electric conductivity.

The present invention relates to a polymeric foam base material comprising a plurality of pores in order to improve electrical conductivity while having excellent mechanical properties. And a plating layer formed on an outer surface and a pore surface of the polymer foam base material.

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.

The present invention relates to a polymeric foam base material comprising a plurality of pores; And a plating layer formed on the outer surface and the pore surface of the polymer foam base material.

Some of the pores of the polymer foam base material may be connected to each other to form a passage.

The polymer foam base material may be selected from the group consisting of polyethylene, polyprooylene, polyurethane, polyethyleneterephthalate, polyurea, polyvinylchloride, polyvinylacetate, ethylene And may include one or more materials selected from the group consisting of ethylenevinylacetate, melamine, phenol and acryl.

The porosity of the polymer foam base material may be within 5%.

The plating layer may include at least one material selected from the group consisting of gold, nickel, molybdenum, aluminum, copper, palladium, platinum, silver, tin, titanium and tungsten.

The thickness of the plating layer may be 1 nm to 100 탆.

And a gas permeation preventing layer formed on at least one surface of the separator.

The gas permeation preventive layer may include one or more materials selected from the group consisting of polyethylene, polyprooylene, and polyethyleneterephthalate.

The total thickness of the separator plate may be between 0.1 mm and 2 mm.

The bending strength of the separator may be 250 MPa or more.

The electrical conductivity of the separator may be between 10 < ² > S / cm and 10 < ³ > S / cm.

The contact resistance of the separator is 10 m < ≪ / RTI >

In one embodiment of the present invention, there is provided a method of preparing a polymer foam, comprising: preparing a polymer foam comprising a plurality of pores; Forming an outer surface and a pore surface of the polymer foam to form a plating layer; And laminating a gas permeation preventive layer on at least one side of the polymer foam having the plated layer formed thereon, followed by thermocompression bonding to form a gasket.

The porosity of the polymer foam may be between 10% and 90%.

The plating may be performed by electroplating, electroless plating or PVD.

The thermocompression bonding can be performed by hot press at a temperature of 50 to 300 DEG C and a pressure of 500 to 30,000 kg / cm < 2 >.

The separator for a fuel cell according to the present invention comprises: a polymer foam base material including a plurality of pores; And a plating layer formed on the outer surface and the pore surface of the polymer foam base material, wherein a part of the pores of the polymer foam base material are connected to each other to form a conductive path by the plating layer, thereby being excellent in both mechanical properties and electrical properties .

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 schematically shows a cross-sectional view of a separator for a fuel cell according to an embodiment of the present invention. FIG.
2 is a schematic view illustrating a method of manufacturing a separator for a fuel cell according to an embodiment of the present invention.

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.

The drawings are enlarged to clearly illustrate the layers and regions in the drawings. In the drawings, for the convenience of explanation, the thicknesses of some layers and regions are exaggerated.

The formation of an arbitrary structure on the " one side " of the description means not only that an arbitrary structure is formed in contact with the upper surface (or lower surface) of the substrate, but also an arbitrary structure formed on the substrate and the upper surface The present invention is not limited to this configuration.

Separator plate for fuel cells

The present invention relates to a polymeric foam base material comprising a plurality of pores; And a plating layer formed on the outer surface and the pore surface of the polymer foam base material.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 schematically shows a cross-sectional view of a separator for a fuel cell according to an embodiment of the present invention. FIG.

1, a separator for a fuel cell according to an embodiment of the present invention includes a polymer foam base material 10 including a plurality of pores 15, 15 '; And a plating layer (20) formed on the outer surface and the pore surface of the polymeric foam base material (10).

Further, it may further include a gas permeation preventing layer 30 formed on at least one surface of the separator plate.

Conventionally, a graphite material is mainly used as a base material of a separator for a fuel cell. Specifically, the separator for the fuel cell was manufactured by milling the graphite according to the flow path shape. In this case, the mechanical properties of the separator for the fuel cell were low, and the cost of the fuel cell stack was over 50% There is a problem that it occupies a specific weight.

As an alternative to such a graphite material, a material obtained by mixing a conductive powder with a polymer material can be used as a base material of a separator for a fuel cell. However, in this case, the mechanical properties are excellent, but it is difficult to secure the dispersibility of the conductive powder, .

In addition, the environment inside the fuel cell is an environment in which the concentration of hydrogen ions is high and is easily corroded at a high temperature. Therefore, when the metal material is used as a base material for a fuel cell separator, the surface must have sufficient corrosion resistance. Therefore, a method of coating a metal such as gold, platinum, or tungsten, which has excellent corrosion resistance, on the surface of a base material is indispensable. However, such a coating is not easy to process and has a problem in cost due to expensive metal.

Accordingly, the present invention is characterized in that a polymer foam containing a plurality of pores is used as the base material 10 of the separator plate for a fuel cell. The polymer foam base material 10 is advantageous in that it can be made lighter and thinner.

Specifically, the polymer foam base material 10 is formed by thermocompression molding of a polymer foam, and a part of the pores of the polymer foam base material are open-cellized by thermocompression molding and connected to each other to form a passage 15 , And the remaining part may be present (15 ') in a closed cell form rather than being open-cellized by thermo-compression molding. At this time, it is preferable that the pores of the polymeric foam base material 10 are all open-shaped and not closed-shaped, in view of mechanical properties, but the present invention is not limited thereto.

That is, some of the pores of the polymeric foam base material 10 may be connected to each other to form the passages 15 in the X-Y-axis (longitudinal and lateral) and Z-axis (height) directions.

Specifically, the porosity of the polymer foam base material 10 is numerically expressed by a closed cell. The porosity of the polymer foam base material 10 is preferably within 5%, more preferably 0%, but is not limited thereto. Do not. At this time, since the porosity of the polymer foam base material 10 is mostly open-cellized due to thermo-compression molding of the polymer foam, it has a lower porosity than that of the polymer foam, and finally has a porosity close to 0%.

The polymer foam may be selected from the group consisting of polyethylene, polyprooylene, polyurethane, polyethyleneterephthalate, polyurea, polyvinylchloride, polyvinylacetate, ethylene vinyl But are not limited to, one or more materials selected from the group consisting of ethylenevinylacetate, melamine, phenol and acryl.

The plating layer 20 is formed on the outer surface and the pore surface of the polymeric foam base material 10 and is formed in a discontinuous discrete island shape on the surface of the polymeric foam base material 10, And may be formed in the form of a film. The pore surface of the polymer foam base material 10 in which the plating layer 20 is formed is a surface of the polymer foam base material 10 in which a part of the pores of the polymer foam base material 10 are open- Surface.

The plating layer 20 is formed on the outer surface and the pore surface of the polymeric foam base material 10 so that the conductive path 15 is formed by the plating layer 20 in the XY axis direction and the Z axis direction Thereby, there is an advantage that the electric conductivity can be greatly improved.

The plating layer 20 preferably includes at least one material selected from the group consisting of gold, nickel, molybdenum, aluminum, copper, palladium, platinum, silver, tin, titanium and tungsten.

The thickness of the plating layer 20 is preferably 1 nm to 100 μm, but is not limited thereto. When the thickness of the plated layer 20 is less than 1 nm, it is difficult to sufficiently secure the conductive path. When the thickness of the plated layer exceeds 100 탆, the polymer foam with the plated layer is not compressed properly during the hot- Pores and cracks may be additionally generated, and the moldability is deteriorated.

And a gas permeation preventing layer 30 formed on at least one surface of the separator plate. The gas permeation preventing layer 30 is a layer for preventing gases passing through the channel from being transmitted to the outside. When the gas permeation preventing layer 30 is formed in the gasket direction on the lower surface of the separator plate, And it is more preferable that the gas permeation preventing layer 30 is formed in the direction of the gas diffusion layer on the upper surface of the separator in terms of lowering the corrosion resistance.

The gas permeation preventive layer 30 preferably includes at least one material selected from the group consisting of polyethylene, polyprooylene, and polyethylene terephthalate, but is not limited thereto.

The total thickness of the separator plate is preferably from 0.1 mm to 2 mm, but is not limited thereto. In this case, when the total thickness of the separator is less than the above range, there is a problem that the separator does not function properly as a separator. When the total thickness of the separator exceeds the above range, There is a problem that the weight and size of the plate can not be achieved.

The bending strength of the separator may be 250 MPa or more, which is excellent in mechanical properties.

The electrical conductivity of the separator may be 10 < ² > S / cm to 10 < ³ > S / cm, and the contact resistance of the separator may be 10 m &

Manufacturing method of separation plate for fuel cell

The present invention also provides a method of manufacturing a polymer foam, comprising: preparing a polymer foam base material including a plurality of pores; Forming a plating layer by plating an outer surface and a pore surface of the polymer foam base material; And laminating a gas permeation preventive layer on at least one side of the polymer foam base material having the plated layer formed thereon, followed by thermocompression bonding to form a molding.

2 is a schematic view illustrating a method of manufacturing a separator for a fuel cell according to an embodiment of the present invention.

Referring to FIG. 2, a method of manufacturing a separator for a fuel cell according to an embodiment of the present invention includes: preparing a polymer foam including a plurality of pores (S10); (S20) forming a plating layer by plating an outer surface and a pore surface of the polymer foam; And a step (S30) of laminating a gas permeation preventive layer on at least one side of the polymer foam having the plated layer formed thereon, followed by thermo compression bonding.

First, a polymer foam containing a plurality of pores is prepared (S10).

The porosity of the polymer foam is preferably 10% to 90%, but is not limited thereto. If the porosity of the polymer foam is less than 10%, the coating layer may not be uniformly distributed within the polymer foam. If the porosity of the polymer foam exceeds 90%, the mechanical strength may decrease or the gas may be irrelevant There is a problem that it is transmitted.

The concrete material of the polymer foam is as described above.

Next, the outer surface and pore surface of the polymer foam are plated to form a plated layer (S20). The plating layer is as described above.

The plating may be performed by electrolytic plating, electroless plating or PVD, thereby plating the outer surface and the pore surface of the polymer foam base material to a uniform thickness. Considering the continuous process and the adhesion of the plating layer, it is preferable to form the plating layer by electrolytic plating or electroless plating, but the present invention is not limited thereto.

For example, gold plating uses a plating solution in which 2 mg / l of Au (CN) ₂ is added to a mixed solution of 3M H ₂ SO ₄ solution, 5% HCl solution and 60 g / l KCN and 40 g / l K ₂ CO ₃ And nickel plating may be performed using a plating solution to which ₂ mg / l NiCl ₂ is added in a 5% HCl solution. The plating can be performed at a reduction current of 40 mA / cm 2 at a temperature of 60 ° C.

Finally, the gas permeation preventive layer is laminated on at least one side of the polymer foam having the plated layer formed thereon, followed by thermo compression bonding (S30).

The gas permeation preventing layer is as described above.

The thermocompression bonding can be performed by hot press at a temperature of 50 to 300 DEG C and a pressure of 500 to 30,000 kg / cm < 2 >. The polymer foam is thermally compressed by the hot press under the above-mentioned temperature and pressure conditions, so that some of the pores of the polymer foam base material are connected to each other to form a conductive path by the plating layer.

In addition, the separator may be formed with a reaction gas flow path for discharging surplus gas and reaction products to the outside, while supplying a fuel gas or an oxidizing agent gas, which is a reaction gas, to a corresponding surface of the membrane electrode assembly. Such a reaction gas flow path may be formed as a separate component and then attached to the separator for fuel cell, but it may be formed as a channel like a groove on one side of the separator plate when thermocompression bonding. That is, an oxidant gas flow path is formed in the cathode separation plate on the surface facing the membrane electrode assembly, and an oxidizing agent gas (also referred to as a "reducing gas") containing oxygen is introduced into the oxidizing agent gas flow path. In the anode separation plate, a fuel gas flow path is formed on the surface facing the membrane electrode assembly, and the fuel gas containing hydrogen flows into the fuel gas flow path.

Hereinafter, preferred embodiments of the present invention will be described in order to facilitate understanding of the present invention. However, the following examples are provided only for the purpose of easier understanding of the present invention, and the present invention is not limited by the following examples.

[ Example ]

Example  One

A polypropylene foam (porosity = 20%) containing a plurality of pores was prepared. The outer surface of the foam base material and the surface of the pores (passages formed by connecting some of the pores) were plated by nickel electroless plating to form a plating layer having a thickness of about 1 탆. Thereafter, a gas permeation preventive layer made of polypropylene having a thickness of about 0.1 cm was laminated on the lower surface (in the gasket direction) of the foam base material having the plated layer formed thereon, followed by hot pressing at a pressure of about 10,000 kg / Followed by thermocompression molding to produce a separator plate for a fuel cell (200 mm x 200 mm x 1 mm).

Example  2

A separator for fuel cells was prepared in the same manner as in Example 1, except that the gas permeation preventive layer was laminated on both the upper surface (gas diffusion layer direction) and the lower surface (gasket direction) of the foam base material having the plated layer formed thereon.

Comparative Example  One

A separator plate (200 mm x 200 mm x 1 mm) for a fuel cell made of graphite was prepared.

Comparative Example  2

(200 mm x 200 mm x 1 mm) made of polypropylene and containing a conductive powder of nickel (Ni) was prepared.

Experimental Example

One. Flexural strength  Measure

The bending strengths of the separators for fuel cells prepared in Examples 1 and 2 and Comparative Examples 1 and 2 were measured according to ASTM D 790.

2. Electrical conductivity and contact resistance measurement

The electrical conductivity and contact resistance of the fuel cell separator plates prepared in Examples 1 and 2 and Comparative Examples 1 and 2 were measured by a 4-probe method using a Keithley / 6220 / 2182A, USA instrument Lt; / RTI >

The bending strength, electrical conductivity and contact resistance measurement results as described above are summarized in Table 1 below.

Flexural Strength (MPa) Electrical Conductivity (S / cm) Contact resistance (mΩ · ㎠) Example 1 350 130 9.8 Example 2 360 120 9.9 Comparative Example 1 94 1333 9.3 Comparative Example 2 40 20 200

As shown in Table 1, it was confirmed that the separators for fuel cells manufactured in Examples 1 and 2 were excellent in bending strength, electrical conductivity and contact resistance.

On the other hand, it was confirmed that the separator for fuel cell manufactured in Comparative Example 1 had excellent electrical conductivity and contact resistance, but had a problem that the flexural strength was greatly lowered. In the separator for fuel cell manufactured in Comparative Example 2, It is confirmed that there is a problem that the electrical conductivity is greatly lowered and the contact resistance is greatly increased.

It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

Claims (16)

A polymer foam base material including a plurality of pores; And
And a plating layer formed on an outer surface and a pore surface of the polymer foam base material
Separator plate for fuel cell.
The method according to claim 1,
Wherein some of the pores of the polymer foam base material are connected to each other to form a passage
Separator plate for fuel cell.
The method according to claim 1,
The polymer foam base material may be selected from the group consisting of polyethylene, polyprooylene, polyurethane, polyethyleneterephthalate, polyurea, polyvinylchloride, polyvinylacetate, ethylene And at least one material selected from the group consisting of ethylenevinylacetate, melamine, phenol, and acryl.
Separator plate for fuel cell.
The method according to claim 1,
The porosity of the polymer foam base material is within 5%
Separator plate for fuel cell.
delete The method according to claim 1,
The thickness of the plating layer is preferably from 1 nm to 100 mu m
Separator plate for fuel cell.
The method according to claim 1,
Further comprising a gas permeation preventing layer formed on at least one surface of the separator plate
Separator plate for fuel cell.
8. The method of claim 7,
Wherein the gas barrier layer comprises one or more materials selected from the group consisting of polyethylene, polyprooylene, and polyethyleneterephthalate
Separator plate for fuel cell.
The method according to claim 1,
The total thickness of the separator plate is 0.1 mm to 2 mm
Separator plate for fuel cell.
The method according to claim 1,
The bending strength of the separator plate is preferably 250 MPa or more
Separator plate for fuel cell.
The method according to claim 1,
The electrical conductivity of the separator is 10 < ² > S / cm to 10 < ³ &
Separator plate for fuel cell.
The method according to claim 1,
The contact resistance of the separator is preferably 10 m <
Separator plate for fuel cell.
Preparing a polymer foam comprising a plurality of pores;
Forming an outer surface and a pore surface of the polymer foam to form a plating layer; And
A step of laminating a gas permeation preventive layer on at least one side of the polymer foam having the plated layer formed thereon,
A method of manufacturing a separator plate for a fuel cell.
14. The method of claim 13,
The porosity of the polymer foam is 10% to 90%
A method of manufacturing a separator plate for a fuel cell.
14. The method of claim 13,
The plating may be performed by electroplating, electroless plating or PVD processes
A method of manufacturing a separator plate for a fuel cell.
14. The method of claim 13,
The thermocompression bonding is performed by a hot press at a temperature of 50 캜 to 300 캜 at a pressure of 500 kg / cm 2 to 30,000 kg / cm 2
A method of manufacturing a separator plate for a fuel cell.

Images