KR20160092266A - Method for manufacturing fuel cell separator plate - Google Patents

Abstract

The present invention relates to a producing method of a fuel cell separator, comprising the steps of: producing a prepreg plate of a non-conductive material; forming a prepreg multi-cell pattern by processing the prepreg plate; combining the prepreg multi-cell pattern and a conductive material; and forming the combined prepreg multi-cell pattern and the conductive material.

Description

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

 The present invention relates to a method of manufacturing a fuel cell separator, and more particularly, to a method of manufacturing a multi-cell fuel cell separator.

 Fuel cells are attracting attention as one of the renewable energy sources, as the importance of future renewable energy is highlighted by the depletion of fossil fuels. Fuel cells have the advantage of being highly efficient and environmentally friendly by supplying fuel such as hydrogen and oxygen in the atmosphere to the cells and utilizing the electric energy generated in the process of making water by the electrochemical reaction between them. The stack, which is a main part of the fuel cell system, is a stacked unit cell, and one cell consists of a membrane electrode assembly (MEA) and a bipolar plate (separator).

Among them, separator plates for fuel cells are mainly divided into metal separator plates and polymer composite separator plates, and researches on polymer composite separator plates which do not cause corrosion problems have been continuously carried out. In recent years, research and development on the development of a new concept of separation plates such as large-area separators and multi-cell separators have been underway to secure market competitiveness through cost reduction and system volume reduction.

Korean Patent Registration No. 1430286 discloses a method for manufacturing a multi-cell separator, which aims to reduce the manufacturing cost and time of a fuel cell stack and to improve the power conversion efficiency by fabricating a stack of a high voltage with a smaller number of stacked cells Discloses a multi-cell separator having a divided shape in which a conductive portion and a non-conductive portion are combined.

In this prior art, it is disclosed that a multi-cell separator is manufactured through a hot-pressing method using a powder material. In the manufacturing method using such a powder material, two kinds of fine powders The boundary between the conduction part and the non-conduction part after the compression process can not be clearly distinguished due to the difference in the flowability of the material. Accordingly, there is a problem in that it is difficult to secure insulation of the multi-cell separator manufactured by the above-described conventional method.

Korean Patent Registration No. 1430286

It is an object of the present invention to provide a method of manufacturing a fuel cell separator which is excellent in insulation and can provide a multi-cell separator having various patterns.

In order to achieve the above object, a method of manufacturing a fuel cell bipolar plate according to the present invention includes the steps of: preparing a prepreg plate of a nonconductive material; forming a prepreg multi-cell pattern by processing a prepreg plate; , Combining the prepreg multi-cell pattern and the conductive material, and molding the conductive material with the combined prepreg multi-cell pattern.

At this time, the prepreg plate may be in a semi-hardened state.

At this time, the combining step may include the step of putting the conductive material in a powder form into the prepreg multi-cell pattern. Alternatively, the combining step may include inserting a conductive material in the form of a prepreg into the prepreg multi-cell pattern.

The nonconductive material may be a polymeric resin, the conductive material may be a carbon-polymer composite material, and the carbon-polymer composite material may include graphite.

The step of preparing the prepreg plate may be carried out by rolling or by compression molding.

The forming step may include heating and pressing the combined prepreg multi-cell pattern and the conductive material and compression-molding.

Meanwhile, the fuel cell separator according to the present invention includes a non-conductive prepreg multi-cell pattern and a conductive material pattern corresponding to the prepreg multi-cell pattern. At this time, the prepreg multi-cell pattern may have a width of 3 mm or less.

The method of manufacturing a fuel cell bipolar plate according to the present invention has an effect that it is possible to manufacture a multi-cell bipolar plate having excellent insulation by preventing the mixing of a conductive material and a nonconductive material.

The method of manufacturing a fuel cell bipolar plate according to the present invention has the effect of manufacturing complicated and various types of multi-cell bipolar plates.

The method of manufacturing a fuel cell bipolar plate according to the present invention has an effect of providing a fuel cell stack having a high efficiency by relatively increasing an area of a conducting portion with respect to a non-conducting portion in a bipolar plate.

1 is a flowchart illustrating a method of manufacturing a fuel cell bipolar plate according to an embodiment of the present invention.
FIGS. 2 to 6 are schematic views illustrating a method of manufacturing a fuel cell bipolar plate according to an embodiment of the present invention.
7 to 11 are schematic views illustrating a multi-cell pattern of a fuel cell bipolar plate according to an embodiment of the present invention.
12 is an enlarged view of a boundary portion between a conductive portion and a non-conductive portion of a separator plate sample according to a comparative example.
13 is an enlarged view of a boundary portion between a conductive portion and a non-conductive portion of a separator plate sample according to an experimental example.
14 is a graph showing the results of measurement of electrical resistance of a non-conductive portion of a separator plate sample according to a comparative example.
15 is a graph showing the results of measurement of electrical resistance of a non-conductive portion of a separator plate sample according to an experimental example.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and how to accomplish them, will become apparent by reference to the embodiments described in detail below with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. Rather, the embodiments disclosed herein are provided so that the disclosure can be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, the terms "comprises" or "having ", and the like, specify that the presence of stated features, integers, steps, operations, elements, But do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the meaning in the context of the relevant art and are to be interpreted in an ideal or overly formal sense unless expressly defined herein Do not.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. 1 is a flowchart showing a method of manufacturing a fuel cell bipolar plate according to an embodiment of the present invention, and FIGS. 2 to 6 are schematic views showing the process.

As shown in FIG. 1, a method of manufacturing a fuel cell bipolar plate according to an embodiment of the present invention includes a step (S10) of preparing a prepreg plate of a nonconductive material, a step A step (S30) of inserting a prepreg multi-cell pattern into a compression mold, a step (S40) of combining a prepreg multi-cell pattern and a conductive material, and a step (S40) of combining the prepreg multi- And forming a conductive material (S50).

In a step S10 of producing a prepreg plate of a nonconductive material, a semi-hardened process is performed on the nonconductive material 10 at a temperature of 50 to 110 DEG C, and compression, extrusion Or a step of forming the prepreg plate 12 using a molding process such as a roll. At this time, the molding step is preferably carried out under a pressure condition of 100 to 200 tons. In FIG. 2, for example, the non-conductive material 10 is formed into a prepreg plate 12 by using the roll 20.

Here, the nonconductive material 10 used in manufacturing the prepreg plate 12 may be a thermosetting resin or a polymer resin including a thermoplastic resin, and specifically, a phenol resin, an epoxy resin, a benzoxazine resin, a melamine A thermosetting resin such as a resin, a polyurethane resin, a urea resin, an alkyd resin or a polyimide resin and a thermosetting resin such as polypropylene, polyethylene, polyvinylidene fluoride, polymethyl methacrylate Poly (methyl methacrylate), Polycarbonate, Polyphenylene sulfide, Liquid Crystalline Polymer, Polyether ether ketone, Polyimide, Polyethersulfone Polyether sulfone) or other engineering plastics may be used.

Next, as shown in Fig. 3, the prepreg plate 12 is processed to form the prepreg multi-cell pattern 14 (S20). At this time, the prepreg plate 12 may be machined and cut to form a predetermined multi-cell pattern 14 as shown in Fig.

According to the present embodiment, it is possible to manufacture complicated and various types of multicell patterns by machining and cutting the prepreg plate 12, and it is possible to form a pattern having a width of 3 mm or less or 1 mm or less through precision processing can do. As described above, by manufacturing a precise multi-cell separator pattern, it is possible to increase the relative area of the conducting portion in the separator, thereby increasing the efficiency of the fuel cell itself.

FIGS. 7 to 11 illustrate a multi-cell pattern according to the manufacturing method of the present invention. By the manufacturing method according to the embodiment of the present invention, a separation plate having four or more divided cells as shown in FIG. 8 is manufactured And it is possible to manufacture a separator having complex and various shapes as shown in Figs. 9 to 11. Fig. In addition, according to the present embodiment, an outer manifold portion, which does not require electrical conductivity for the purpose of improving the strength or the like, can be formed of a nonconductive material, Can be prepared.

Next, as shown in Fig. 4, the prepreg multi-cell pattern 14 is inserted (S30) so as to match the position of the compression mold 16.

Next, as shown in Fig. 5, a conductive material 18 is prepared, and a prepreg multi-cell pattern 14 and a conductive material 18 are combined (S40). For example, the combination of the prepreg multi-cell pattern 14 and the conductive material 18 can be achieved by putting the conductive material 18 in a powder form into the prepreg multi-cell pattern 14.

In another example, the conductive material 18 in the form of a prepreg may be inserted into the prepreg multi-cell pattern 14. In this case, a prepreg plate (not shown) of a conductive material is manufactured by semi-curing and molding the conductive material in a similar manner to the above-described prepreg plate 12 of the nonconductive material, A pattern (not shown) corresponding to the prepreg multi-cell pattern 14 may be separately formed and inserted into the multi-cell pattern of the nonconductive material.

As the conductive material 18, a material in which a non-conductive polymer resin and a conductive filler are mixed may be used. As the polymer resin, the same material as that used in manufacturing the above-mentioned prepreg plate may be used.

Examples of the conductive filler for the conductive material 18 include carbon powder, graphite, carbon black, acetylene black, ketjen black, denka black, super P, activated carbon, carbon nanotube, carbon nanofiber, carbon nanowire, a carbon nano-horn, a carbon nano ring, and mixtures thereof.

At this time, the conductive filler preferably has an average particle diameter of 1 to 200 mu m. When the average particle size of the conductive filler is less than 1 탆, there is a fear of aggregation of the conductive filler. When the average particle size of the conductive filler exceeds 200 탆, it is disadvantageous for molding and sealing.

The amount of the conductive filler to be used is preferably 500 to 2500 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 electrical conductivity of the separator may be lowered. If the amount exceeds 2500 parts by weight, the processability and gas tightness of the separator for fuel cells may be deteriorated.

The conductive material 18 may further include an additive in addition to the polymer resin and the conductive filler. Specifically, when a thermosetting resin is used as the polymer resin, it may further include a curing agent. As the curing agent, at least one of an amine compound, an acid anhydride compound, a polyamide compound, a polysulfide compound and a phenol resin can be selected and used. The amount of the curing agent added is preferably 30 to 70 parts by weight based on 100 parts by weight of the thermosetting resin. If the content of the curing agent is less than 30 parts by weight, the unreacted thermosetting resin may remain, and if it exceeds 70 parts by weight, a part of the curing agent may remain unreacted.

Further, in order to shorten the curing time, a curing accelerator may be further used together with the curing agent. As the curing accelerator, basic compounds such as triphenylphosphine (TPP) diaminodiphenylsulfone (DDS), tertiary amines or imidazoles and derivatives thereof can be used. At this time, 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 prolonged and the work is easy, but the curing speed is slow, so that the molding time may be long. If the content is more than 8 parts by weight, the curing speed may be accelerated.

When the conductive material 18 further comprises a curing agent and a curing accelerator, 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 with the conductive filler, A pulverizing step can be optionally further carried out for the mixture of the 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 pulverizing process, more homogeneous mixing can be performed and quick curing reaction can be induced in the molding.

The mixing process of the polymer resin and the conductive filler may be carried out by a usual method such as dry mixing or wet (liquid phase) mixing, and a wet mixing method using a solvent is preferable for more homogeneous mixing. As the solvent, methylethylketone (MEK), benzene, or acetone may be used, but the solvent is not limited thereto.

As described above, by using the prepreg multi-cell pattern 14 instead of the non-conductive powder, it is possible to prevent the incorporation of the powder due to the falling of the powder in the mold, unlike the case of using the conventional powder form.

Next, the combined prepreg multi-cell pattern 14 and the conductive material 18 are processed to form a multi-cell separator (S50). 6, the combined prepreg multi-cell pattern 14 and the conductive material 18 located in the compression mold 16 are heated and pressurized using a compression molding apparatus 30, for example, .

As described above, according to the method of manufacturing a fuel cell bipolar plate according to the embodiment of the present invention, it is possible to manufacture a multi-cell separator having excellent insulation by preventing the mixing of the conductive material and the nonconductive material, It is possible to manufacture a separator plate. Also, it is possible to provide a fuel cell stack having a high efficiency by relatively increasing the area of the conducting portion with respect to the non-conducting portion in the separator plate.

Experimental Example

Hereinafter, an experimental example of the present invention will be described in detail. The experimental examples described below are merely examples for confirming the effect of the present invention, and the present invention is not limited to the following experimental examples.

Experimental Example  One

As a test example, a multi-cell separator was manufactured using a prepreg multi-cell pattern according to the method of the above-described embodiment. As a comparative example, a multi-cell separator was manufactured by using a conductive powder and a non- The cell separator was fabricated and the boundary between the conducting portion and the non-conducting portion of each multi-cell separator was observed.

As the conductive material, 60 parts by weight of a phenol resin as a curing agent and 3 parts by weight of TPP as a curing accelerator were stirred using a solvent as a curing agent for 100 parts by weight of the epoxy resin solid particles, and then 500 parts by weight of graphite having a particle size of 20 to 100 μm was kneaded. Were mixed and dried.

The nonconductive material was manufactured by using aluminum oxide, silica or glass powder, which is an insulating inorganic fine particle, as a filler in the same amount of the above resin.

Also, the prepreg multi-cell pattern and the conductive material were compacted at a pressure of 300 to 500 tons at a temperature of 130 to 170 degrees using a compression molding apparatus.

FIG. 12 is an enlarged view showing a boundary of a multi-cell separator manufactured according to a comparative example, and FIG. 13 is an enlarged view showing a boundary of a multi-cell separator manufactured according to the present example. As shown in FIG. 12, in the conventional multi-cell separator using the powder injection method, the mixing occurs at the boundary between the conductive portion and the nonconductive portion, and both regions are invaded by the pressure of the compression molding and the flow of the material. .

On the other hand, as shown in FIG. 13, the boundary between the conductive portion and the non-conductive portion of the multi-cell separator fabricated according to the present experimental example was clearly distinguished, and it was confirmed that the mixing of the materials did not occur.

According to the result of the experiment, the accuracy of the pattern of the conductive portion and the non-conductive portion is improved when the method of manufacturing the separator according to the present invention is applied, thereby improving the stack efficiency by reducing the area ratio of the non- . It is considered that it is possible to manufacture a separator having a nonconductive boundary formed at a width of 3 mm or less or 1 mm or less when the separator is manufactured by processing the prepreg with precision processing technology.

Experimental Example  2

The electrical resistance values of the multi-cell separator samples according to the 20 experimental examples and the comparative example were measured by using a multimeter on the left and right conductive parts around the nonconductive part.

FIGS. 14 and 15 are graphs showing the insulation yield rate according to the comparative example and the manufacturing method of the present experimental example, respectively. As a result, the separator according to the comparative example had a yield of 70%, and the separator according to the present example showed a yield of 95%.

As shown in Fig. 14, in the comparative example, even when the electrical resistance value is determined to be good, a considerable number of separation plates of about 1 MΩ, which is the reference point level, were found (Comparative Samples 12 and 18) There were also. (Comparative Examples 4 and 15)

On the other hand, as shown in FIG. 15, in the case of the separator according to the experimental example, it was confirmed that the resistance of all the separator plates judged as good is measured infinitely, and the insulation is greatly improved as compared with the conventional technology.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood that the invention may be practiced. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

10: nonconductive material 12: prepreg plate
14: prepreg multi-cell pattern 16: compression mold
18: conductive material 20: roll
30: Compression molding device

Claims (15)

Fabricating a prepreg plate of nonconductive material,
Forming a prepreg multi-cell pattern by processing the prepreg plate;
Combining the prepreg multi-cell pattern and the conductive material, and
And forming the conductive prepreg multi-cell pattern and the conductive material
Wherein the fuel cell separator comprises a plurality of fuel cells. The method according to claim 1,
Wherein the combining comprises:
And injecting the conductive material in powder form into the prepreg multi-cell pattern. The method according to claim 1,
Wherein the combining comprises:
And inserting the conductive material in the form of a prepreg into the prepreg multi-cell pattern. The method according to claim 1,
Wherein the nonconductive material is a polymeric resin. The method according to claim 1,
Wherein the conductive material is a carbon-polymer composite material. The method according to claim 1,
Wherein the step of preparing the prepreg plate is performed by rolling. The method according to claim 1,
Wherein the step of preparing the prepreg plate is performed by compression molding. 8. The method of claim 7,
Wherein the prepreg plate is in a semi-hardened state. 9. The method according to any one of claims 1 to 8,
Wherein the forming step includes heating and pressing the combined prepreg multi-cell pattern and the conductive material to perform compression molding. Non-conductive prepreg multi-cell pattern, and
A pattern of a conductive material corresponding to the prepreg multi-
And a fuel cell separator. 11. The method of claim 10,
Wherein the conductive material pattern has a powder phase. 11. The method of claim 10,
Wherein the conductive material pattern has a prepreg shape. 11. The method of claim 10,
Wherein the nonconductive material is a polymer resin. 11. The method of claim 10,
Wherein the conductive material is a carbon-polymer composite material. 11. The method of claim 10,
Wherein the prepreg multi-cell pattern has a width of 3 mm or less.

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