KR100804727B1 - Bipolar plate for fuel cell - Google Patents

Abstract

According to the present invention, in a bipolar plate for a fuel cell, which is disposed on both sides of a thin film electrode assembly, a gas flow path for supplying hydrogen and oxygen, and a separator for preventing direct contact between hydrogen and oxygen are integrally formed of a metal material. The separator is provided with a bipolar plate for a fuel cell, characterized in that grooves having a width and a depth equal to the gas flow path are formed along the edge thereof. According to the disclosed fuel cell bipolar plate, the separator and the gas flow path are integrally stamped and molded, thereby enabling mass production of the fuel cell bipolar plate at low cost, and having the same width and depth as each channel formed in the separator. Branches are formed in a double arrangement along the edge of the separator plate so that the gas flow path of the separator plate and the edge portion receive even compressive force from the precision mold, so that the edges of the separator plate are twisted during stamping. There is an effect to prevent the phenomenon.

Fuel Cell, Bipolar Plate, Stamping, Groove

Description

Bipolar plate for fuel cell

1 is a cross-sectional view showing a schematic structure of a fuel cell,

2 is a plan view of a bipolar plate for a conventional fuel cell,

3 is a plan view of a bipolar plate for a fuel cell according to an embodiment of the present invention,

4 is a cross-sectional view taken along the line IV-IV shown in FIG. 3.

<Explanation of symbols for the main parts of the drawings>

Bipolar plate for fuel cell 110 Separator

120 gas passage 130 manifold

140 ... Groove

The present invention relates to a bipolar plate, and more particularly, by forming a flow path through which hydrogen and oxygen gas, which are fuels of a polymer electrolyte fuel cell, flow, thereby smoothing gas flow, thereby reducing pressure due to a sudden change in flow rate. The present invention relates to a bipolar plate for a fuel cell, which reduces the power consumption and enables a constant supply of reaction gas.

In general, fuel cells have no vibration or noise during power generation, and produce electricity directly by reacting hydrogen contained in a hydrocarbon-based fuel with oxygen in the air by electrochemical method, so that chemical energy is converted into mechanical energy. Compared to the engine, the power generation efficiency is high, electricity and heat can be used simultaneously, and the fuel used can also use natural gas, methanol, naphtha, or coal, so that fuel can be diversified, and in particular, carbon dioxide emissions can be suppressed. Therefore, it is possible to solve the environmental pollution problem. Recently, active researches are being carried out both domestically and abroad.

1 is a cross-sectional view showing a schematic structure of a fuel cell.

Referring to the operation of the fuel cell with reference to the drawings, the hydrogen flowing to the anode (Anode) 5 is separated into electrons and hydrogen ions, the hydrogen ions are moved through the electrolyte (6) electrons in the cathode (Cathode) 7, Oxygen ions and hydrogen ions combine to form water. At this time, the electrons generated in the anode 5 do not pass through the electrolyte 6, and move to the cathode 7 through an external circuit (not shown). Through this process, electricity and water are generated, and a catalyst layer is formed in the anode 5 and the cathode 7 to promote the reaction.

The separator 3 is attached to both sides of the membrane electrode assembly (MEA; MEA) composed of the anode 5, the electrolyte 6, and the cathode 7, and supplies hydrogen and oxygen as fuels. It serves to collect and to prevent the risk of explosion, combustion, etc. in direct contact of hydrogen and oxygen. Therefore, the separator 3 should have low gas permeability and good electrical conductivity for active electron transfer.

The gas flow path 2 may be formed integrally or separately with the separator 3, supply hydrogen and oxygen to each electrode 5, 7, supply water to the electrolyte 6, and remove reactant water. Because it plays a role, corrosion resistance should be good.

The bipolar plate 1 including the separator plate 3 and the gas flow passages 2 formed on both sides thereof should have high electrical conductivity, be light, have low gas permeability, and be competitive in mass production. It is required to have corrosion resistant properties.

As a material of such a bipolar plate, graphite is mainly used among carbon-based materials. However, the graphite has a disadvantage in that the processing cost is excessive during machining, the handling and storage is difficult due to the brittleness of the material itself, and the size is large and the weight is difficult to reduce, making mass production difficult.

In fact, as shown in FIG. 2, the present inventors stamped a metal separator plate 11 to form a gas flow passage 12 integrally with the separator plate 11 to form a fuel cell bipolar plate 10. Disclosed is to solve such problems of the prior art.

According to the bipolar plate 10 for a fuel cell, it is made of stainless steel, has high electrical conductivity, corrosion resistance, and low gas permeability, and has structurally robust durability, and the separator 11 and the gas flow path ( 12) is integrally stamped and molded so that mass production is possible at low cost.

However, in the prior art of the present applicant, in the process of forming the gas flow path 12 by stamping the separating plate 11, the portion in which the gas flow path 12 is formed and the gas flow path 12 are not formed. Distortion may occur at the edge of the separator 11 due to the difference in the compressive force generated between the outer edge portions, which is not the outer edge portion, and the sealing performance of the bipolar plate 10 for fuel cells is deteriorated. There is a risk that the gas flowing through the gas flow passage 12 leaks into the fuel cell.

The present invention has been made to solve the above problems, to provide a bipolar plate for a fuel cell improved structure so that the entire separation plate receives a uniform pressing force during the stamping process so that the distortion of the separation plate does not occur. There is this.

Other objects and advantages of the invention will be described below and will be appreciated by the embodiments of the invention. In addition, the objects and advantages of the invention may be realized by the means and combinations indicated in the claims.

The bipolar plate for a fuel cell of the present invention for achieving the above object is disposed on both sides of the thin film electrode assembly, the gas flow path for supplying hydrogen and oxygen, and the separator plate for preventing direct contact of hydrogen and oxygen is metal A bipolar plate for a fuel cell integrally formed with a material, the separator comprising a separator having a groove having the same width and depth as the gas flow path along an edge thereof.

Here, it is preferable that the groove has a double arrangement structure in which a pair is formed along the edge of the separator.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the present specification and claims should not be construed as being limited to the common or dictionary meanings, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention.

Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

3 is a plan view of a bipolar plate for a fuel cell according to an embodiment of the present invention, Figure 4 is a cross-sectional view taken along the line IV-IV shown in FIG.

First, referring to FIG. 3, the bipolar plate 100 according to the preferred embodiment of the present invention includes a separator plate 110, a gas flow path 120 integrally formed in the separator plate 110, and a manifold. The unit 130 and the groove 140 is included.

The separator 110 is attached to both sides of the thin film electrode assembly, and serves to supply hydrogen and oxygen as fuel and to collect current, and to prevent risks such as explosion and combustion during direct contact of hydrogen and oxygen. To carry out, it is formed of a metal material having high electrical conductivity and corrosion resistance and low gas permeability, preferably, it may be made of SUS 304 material which is stainless steel, which is strong corrosion resistance and easy to precision casting.

The gas flow path 120 is integrally formed on one surface or both surfaces of the separation plate 110 using the same material as the separation plate 110, and has a meandering shape including first and second channel parts 121 and 122. It is preferably formed.

The first channel part 121 includes a plurality of channels and starts from one side of the surface of the separator plate 110 to the other side of the surface of the separator plate 110 through the center of the surface of the separator plate 110. It is formed integrally. Here, each channel included in the first channel part 121 is disposed to be adjacent to each other in parallel.

Each channel of the first channel part 121 is bent in the vertical direction several times while always being parallel to two sides of the separator plate 110 and perpendicular to the other two sides of the separator plate 110 surface. After leading to the center of the, and from the center to the other side of the surface of the separator 110. As such, each channel is longer than that of each channel formed in a straight line, providing sufficient passage for gas to react to provide a more efficient gas reaction environment.

In addition, it is preferable that each of the channels has the same length as the straight portion is changed through several right angle bends without interrupting the flow of gas by maintaining the cross-sectional shape of the letter “c”. Do. Thereby, the pressure and flow rate imparted by the reaction gas over the entire active surface of the bipolar plate can be kept uniform.

In addition, the second channel portion 122 may have the same shape as the first channel portion 121 and may be disposed to be symmetrical with the first channel portion 121.

Next, the manifold 130 is disposed at both ends of the gas flow path 120, and includes a fuel supply manifold 131, an air supply manifold 132, and a fuel discharge manifold 133. And air exhaust manifold 134.

The fuel supply manifold 131 supplies hydrogen, which is a fuel gas of a fuel cell, to the thin film electrode assembly, and the air supply manifold 132 supplies air to the thin film electrode assembly.

In addition, the fuel discharge manifold 133 removes the unreacted exhaust gas, and the water generated by the redox reaction and the remaining air are discharged through the air discharge manifold 134.

Finally, the groove 140 is formed on the outside of the gas flow path 120 formed in the separation plate 110, is formed with the same width and depth as the gas flow path 120, the It is preferred to have a double arrangement structure in which a pair is formed along the edge.

Below is a brief description of the process of manufacturing the bipolar plate 100 for a fuel cell according to a preferred embodiment of the present invention as described above.

In order to manufacture the bipolar plate 100 for a fuel cell according to a preferred embodiment of the present invention, first, the molding material metal is cut to form a separating plate 110 having a predetermined thickness and size. The molding material metal is preferably made of SUS 304, which is stainless steel, which has high corrosion resistance and is easy to precisely cast.

In addition, it is preferable that the thickness of the separating plate 110 is 0.5 to 1.0 mm, which means that when the thickness of the separating plate 110 is less than 0.5 mm, the gas flow path formed at the same time is insufficient in rigidity for maintaining the shape ( The lower the depth of 120, the less the amount of gas that can flow as well as the gas flow is not smooth, when the thickness of the separation plate 110 exceeds 1.0mm the rigidity of the separation plate 110 is increased more than necessary This is because the gas flow path 110 may not be properly formed in the stamping process to be described later.

Next, when the separation plate 110 is formed, the separation plate 110 is stamped. The stamping process is a process of forming the gas flow path 120 integrally with the separator plate 110 by pressing the separator plate 110 with a precision mold, and accordingly, according to a preferred embodiment of the present invention. The plate 100 has a merit that a mass production process can be performed at low cost by simplifying a process of forming the gas flow path 120 on the separator 110 without requiring complicated machining.

On the other hand, in the process of forming the separation plate 110 and the gas flow path 120 integrally by pressing the separation plate 110 with a precision mold in this way, the portion and the gas flow path 120 is formed in the gas flow path 120 Due to the difference in the compressive force generated between the outer edge portion that is not molded may be a distortion phenomenon in the edge portion of the separation plate (110). Accordingly, the bipolar plate 100 for fuel cells according to the preferred embodiment of the present invention solves this problem by allowing the groove 140 to be formed along the edge of the separator 110. That is, the grooves 140 having the same width and depth as the respective channels 121 and 122 formed in the separator plate 110 are formed in a double arrangement along the edge of the separator plate 110 so that the separator plate 110 is formed. The gas flow path 120 is formed and the edge portion is subjected to an even pressing force from the precision mold, thereby preventing the edge portion of the separation plate 110 is warped.

Finally, when this stamping process is completed, the anti-corrosion treatment is performed to prevent corrosion in long-term use.

Since the SUS 304 material used as the material of the bipolar plate for fuel cells is difficult to heat treatment, as a corrosion prevention method, a nitrogen compound layer is formed on the surface using ammonia gas or nitrogen gas on the metal surface to have high hardness and excellent wear resistance effect. And a chromium metal nitride treatment method capable of obtaining a corrosion resistance effect.

As mentioned above, although this invention was demonstrated by the limited embodiment and drawing, this invention is not limited by this, The person of ordinary skill in the art to which this invention belongs, Of course, various modifications and variations are possible within the scope of equivalents of the claims to be described.

According to the fuel cell bipolar plate of the present invention, since the separation plate and the gas flow path are integrally formed and molded, mass production of the fuel cell bipolar plate is possible at a low cost, and the same width as that of each channel formed in the separator plate. Grooves having a depth are formed in a double arrangement along the edge of the separator plate so that the gas flow path of the separator plate and the edge portion receive evenly compressive force from the precision mold. This warping phenomenon is prevented.

In addition, it is made of stainless steel, which has high electrical conductivity, corrosion resistance and low gas permeability, and has structurally robust durability, and the gas flow path is formed in a meandering shape to provide a sufficient passage for gas to react. Therefore, there is an advantage of providing an efficient gas reaction environment.

Claims (2)

delete In a bipolar plate for a fuel cell disposed on both sides of the thin film electrode assembly, a gas flow path for supplying hydrogen and oxygen, and a separator plate for preventing direct contact of hydrogen and oxygen are integrally formed of a metal material. The separating plate is formed with grooves (Groove) having the same width and depth as the gas flow path along the edge, The groove is a bipolar plate for a fuel cell, characterized in that the double arrangement structure is formed along the edge of the separation plate.

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