JP2006147256A - Fuel battery unit cell and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a fuel battery unit cell capable of restraining deterioration of electromotive force by doing away with a positional shift of a polymer electrolyte film and a separator, and further, capable of preventing leak of fuel gas and oxidant gas. <P>SOLUTION: The method comprises a separator forming process of forming a piece of separator 20 by integrating an anode separator 11 arranged at an anode side and a cathode separator 12 arranged at a cathode side, respectively, of a solid polymer electrolyte film 13, a doubling process of folding the separator 20 in two and arranging the anode separator 11 and the cathode separator 12 in opposition, a thrusting process of thrusting and inserting at least an end part 10A of a membrane electrode assembly 10 against and into the double folded part 22, and a pinching process of pinching in the membrane electrode assembly 10 with the anode separator 11 and the cathode separator 12. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell single cell and a method for manufacturing the same, and more particularly, to a structure of a novel fuel cell single cell in which an anode separator and a cathode separator are formed of a single separator, and a method for manufacturing the same.

  For example, in a fuel cell in which hydrogen and oxygen are supplied to both surfaces of a polymer electrolyte membrane to generate electromotive force, a metal thin plate is pressed to form a gas flow path in order to further increase the electromotive force per unit volume. A so-called thin metal separator that forms a thin film has been developed.

  As a fuel cell using such a thin metal separator, for example, a first separator having a concavo-convex channel is disposed on one side of a bonded body (solid polymer electrolyte membrane), and the other side. In addition, a structure in which a plurality of fuel cell single cells formed by arranging a second separator having a laminated structure in which a leaf spring is sandwiched between two separators each having an uneven channel is laminated (for example, , See Patent Document 1).

In addition, as a fuel cell using a thin metal separator, a metal separator formed by pressing a thin metal plate to form an uneven gas channel is disposed on both surfaces of an electrolyte made of an ion exchange membrane. A plurality of formed fuel cell single cells are stacked.
Japanese Patent Application Laid-Open No. 2002-367665 (Pages 2 and 3; FIGS. 5 and 6) JP 2004-139951 A (pages 5 to 7, FIG. 1 and FIG. 2)

  By the way, in the fuel cells described in Patent Document 1 and Patent Document 2, if the seal between the polymer electrolyte membrane and the separator is not sufficient, a minute fuel gas leaks from between the polymer electrolyte membrane and the separator, and the required electromotive force. It becomes difficult to ensure. Therefore, in order to obtain a necessary electromotive force, it is necessary to sufficiently seal between the polymer electrolyte membrane and the separator.

  Moreover, in these fuel cells, since the separators are stacked and disposed so as to sandwich the polymer electrolyte membrane, when stacked on the basis of the outer shape, the stacking position is shifted, and the entire stack becomes large. In addition, a position shift occurs in the active region that generates the electromotive force of the polymer electrolyte membrane, the active region is substantially lost, and the electromotive force is reduced.

  Accordingly, the present invention provides a fuel cell single cell capable of suppressing a decrease in electromotive force by eliminating positional displacement between the polymer electrolyte membrane and the separator, and preventing gas leakage of fuel gas and oxidant gas, and the same An object is to provide a manufacturing method.

  A fuel cell unit cell according to the present invention includes a membrane electrode assembly having at least a polymer electrolyte membrane, an anode separator disposed on the anode side of the polymer electrolyte membrane, and a cathode side of the polymer electrolyte membrane. A cathode separator. The anode separator and the cathode separator are composed of a single separator, and are folded in half to sandwich the membrane electrode assembly.

  According to the fuel cell single cell of the present invention, the anode separator and the cathode separator are constituted by a single separator, and the membrane electrode assembly is sandwiched between the two separators. be able to. Therefore, since the positions of the active region of the membrane electrode assembly and the flow paths formed in the anode separator and the cathode separator coincide with each other, a necessary electromotive force can be ensured. In addition, when a fuel cell stack is formed by stacking a plurality of fuel cell single cells having no positional shift, stacking does not occur, and the entire stack does not become large.

  Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings.

"Schematic configuration of fuel cell stack"
First, the overall configuration of the fuel cell stack will be briefly described. FIG. 1 is a perspective view showing the overall configuration of the fuel cell stack.

As shown in FIG. 1, the fuel cell stack 1 is a stack in which a predetermined number of fuel cell single cells 2 as unit cells that generate an electromotive force by reaction of fuel gas (H ₂ ) and oxidant gas (O ₂ ) A gas introduction plate 4 for supplying a fuel gas and an oxidant gas to each fuel cell single cell 2 at both ends of the laminate 3, and a fuel gas and an oxidant flowing through each fuel cell single cell 2. It comprises a gas discharge plate 5 for discharging the agent gas from the laminate 3.

  The gas introduction plate 4 includes a fuel gas introduction port 6 for introducing the fuel gas into the fuel gas passage formed in the separator of the fuel cell single cell 2, and an oxidant gas passage formed in the separator. An oxidant gas introduction port 7 for introducing the agent gas is formed. On the other hand, the gas discharge plate 5 has a fuel gas discharge port 8 for discharging the fuel gas flowing through each fuel cell single cell 2 from the stack 3 and an oxidation for discharging the oxidant gas from the stack 3. An agent gas discharge port 9 is formed.

  The fuel cell stack 1 includes a cooling water inlet for circulating cooling water through a coolant channel formed in the separator of each fuel cell single cell 2 and a cooling water outlet for discharging cooling water (whichever Are also omitted).

  As shown in FIG. 2, the fuel cell single cell 2 includes a membrane electrode assembly 10 (MEA: membrane electrode assembly) and an anode separator 11 and a cathode separator 12 that are respectively disposed on both surfaces of the membrane electrode assembly 10. Composed.

  The membrane electrode assembly 10 includes, for example, a solid polymer electrolyte membrane 13 that is a polymer electrolyte membrane that allows hydrogen ions to pass through, an anode electrode 14 that includes an anode catalyst and a gas diffusion layer, and a cathode electrode 15 that includes a cathode catalyst and a gas diffusion layer. It consists of. The membrane electrode assembly 10 has a laminated structure in which the solid polymer electrolyte membrane 13 is sandwiched between the anode electrode 14 and the cathode electrode 15 from both sides. In the membrane electrode assembly 10, reinforcing plates 16 made of, for example, polyethylene terephthalate (PET) are provided at both ends of the solid polymer electrolyte membrane 13 so as to sandwich the solid polymer electrolyte membrane 13.

  The anode separator 11 and the cathode separator 12 are composed of a single separator. After the separator is folded in half and the membrane electrode assembly 10 is sandwiched, one end is caulked and then cut to be divided. Yes. The anode separator 11 is made of a thin metal plate having conductivity and is disposed on the anode side of the solid polymer electrolyte membrane 13. The cathode separator 12 is made of a thin metal plate like the anode separator 11 and is disposed on the cathode side of the solid polymer electrolyte membrane 13.

  The anode separator 11 and the cathode separator 12 are caulked at one end to the reinforcing plate 16 to form a caulking portion 17 and seal between the separator and the membrane electrode assembly 10. Further, the anode separator 11 and the cathode separator 12 are sealed between the separator and the membrane electrode assembly 10 by sealing the other end to the reinforcing plate 16 with a seal member (lip member) 18. .

In the anode separator 11, a fuel gas flow path 19 through which the fuel gas (hydrogen H ₂ ) flows is formed in an uneven shape (so-called corrugated shape) in an active region contributing to power generation (a central region in contact with the anode electrode 14). Has been. In the cathode separator 12, an oxidant gas flow path (not shown) through which an oxidant gas (oxygen O ₂ ) is circulated is formed in the active region as an uneven shape.

  In the fuel cell stack 1 configured as described above, the fuel gas is introduced from the fuel gas inlet 6 and flows through the fuel gas passages 19 formed in the anode separators 11 as shown in FIG. The gas is discharged from the fuel gas outlet 8. The oxidant gas is introduced from the oxidant gas introduction port 7 and flows through the oxidant gas flow path formed in each cathode separator 12, and is then discharged from the oxidant gas discharge port 9.

  As described above, according to the fuel cell single cell 2 of the present embodiment, the anode separator 11 and the cathode separator 12 are constituted by one separator, and the separator is folded in two to form the membrane electrode assembly 10. Therefore, the stacking position of the anode separator 11, the membrane electrode assembly 10 and the cathode separator 12 is not shifted. Further, since there is no stacking position shift among the anode separator 11, the membrane electrode assembly 10, and the cathode separator 12, the shift of the active region can be prevented, and the electromotive force of the fuel cell single cell 2 itself can be increased. it can.

  Further, according to the fuel cell single cell 2 of the present embodiment, the caulking portion 17 is formed in the folded portion, so that the anode separator 11, the membrane electrode assembly 10, and the cathode separator 12 are formed by the caulking portion 17. The gap can be sealed, and leakage of fuel gas and oxidant gas can be prevented.

  In addition, according to the single fuel cell 2 of the present embodiment, since the anode separator 11 and the cathode separator 12 are partially cut, the anode separator 11 and the cathode separator 12 are separated. It can be electrically separated.

"Manufacturing method of fuel cell single cell"
Next, the manufacturing method of the fuel cell single cell 2 comprised as mentioned above is demonstrated. First, as shown in FIG. 3, the anode separator 11 and the cathode separator 12 are integrated to form one separator 20. In other words, the long separator 20 made of a thin metal plate corresponding to two separators is pressed into an irregular shape in the active region to be the anode separator 11 to form the fuel gas channel 19 and the cathode separator 12 is active. The oxidant gas flow path 21 is formed by pressing the uneven shape in the region. The processing of the fuel gas channel 19 and the oxidant gas channel 21 is formed by the same pressing process.

  Next, seal members 18 are formed on both ends of the separators 20 in the longitudinal direction. For example, the sealing member 18 is formed as a ridge having a triangular cross section on the inner surface sandwiching the membrane electrode assembly 10.

  Next, the separator 20 is folded in half at a position where the separator 20 is equally divided (position indicated by a two-dot chain line in FIG. 3), and the anode separator 11 and the cathode separator 12 are arranged to face each other as shown in FIG. In this bending step, the anode separator 11 and the cathode separator 12 are arranged to face each other by folding the separator 20 in half so that the opposing distance is approximately the same length as the thickness dimension of the membrane electrode assembly 10.

  Next, as shown in FIG. 5, the anode separator 11 and the cathode separator 12 are each opened at approximately 90 degrees, leaving the folded portion 22 folded in half. Then, as shown in FIG. 6, the end portion 10 </ b> A of the membrane electrode assembly 10 is inserted into and abutted into the space portion 23 of the bent portion 22. In this abutting step, the end portion 10A of the membrane electrode assembly 10 is positioned by abutting against the bent portion 22, and the relative positional relationship among the anode separator 11, the membrane electrode assembly 10 and the cathode separator 12 is naturally determined.

  Next, the opened anode separator 11 and cathode separator 12 are closed in the direction indicated by the arrow X in FIG. 6, and the membrane electrode assembly 10 is sandwiched between the anode separator 11 and the cathode separator 12. In this clamping step, each of the sealing members 18 formed on the anode separator 11 and the cathode separator 12 is in close contact with the reinforcing plate 16 of the membrane electrode assembly 10 and seals between them.

  Next, after the sandwiching step in which the membrane electrode assembly 10 is sandwiched between the anode separator 11 and the cathode separator 12, as shown in FIG. 7, a part of the bent portion 22 is caulked to form the caulking portion 17. By caulking a part of the bent portion 22, the gap between the anode separator 11 and the membrane electrode assembly 10 and the gap between the cathode separator 12 and the membrane electrode assembly 10 are sealed.

  Finally, a part of the bent portion 22 at a position away from the caulking portion 17 is cut at a position indicated by a two-dot chain line in FIG. In this cutting step, since the integrated separator 20 is cut, the anode separator 11 and the cathode separator 12 are separated. By performing this cutting step, the single fuel cell 2 of the present embodiment shown in FIG. 2 is manufactured.

  According to the manufacturing method of the present embodiment, since the anode separator 11 and the cathode separator 12 are formed by the single separator 20, it is not necessary to separately prepare the anode separator 11 and the cathode separator 12, and the number of parts is reduced. And the manufacturing process can be greatly reduced.

  Also, according to the manufacturing method of the present embodiment, the end 10A of the membrane electrode assembly 10 is abutted against the folded portion 22 that is folded in half, so that the anode separator 11, the membrane electrode assembly 10, and the cathode Misalignment of the stacking position with the separator 12 can be prevented, and misalignment of the active region can be prevented.

  Further, according to the manufacturing method of the present embodiment, after the bi-folding process, the anode separator 11 and the cathode separator 12 are opened leaving the bent portion 22, so that the end portion 10 </ b> A of the membrane electrode assembly 10 to be performed thereafter. It is possible to facilitate the abutting step of inserting and abutting into the bent portion 22.

  In addition, according to the manufacturing method of the present embodiment, the bent portion 22 is caulked after the clamping step, and by this caulking, between the anode separator 11 and the membrane electrode assembly 10 and between the cathode separator 12 and the membrane electrode. The space between the bonded bodies 10 can be sealed.

  In addition, according to the manufacturing method of the present embodiment, since the bent portion 22 is partially cut after the clamping step, the anode separator 11 and the cathode separator 12 can be separated.

  The specific embodiment to which the present invention is applied has been described above, but the present embodiment is not limited to the above-described embodiment, and various modifications can be made.

  FIG. 8 is a perspective view showing an example of a separator in which an insulating member 24 is provided in a half-folded portion. The separator 20 is an integrated separator with an insulating member 24 made of rubber or the like interposed between the anode separator 11 and the cathode separator 12. If the part folded in half is formed by the insulating member 24, the anode separator 11 and the cathode separator can be electrically separated from each other, so that the cutting step of cutting a part of the bent portion 22 can be eliminated after the clamping step. it can.

  FIG. 9 is a schematic process diagram showing an example of another method for manufacturing a fuel cell single cell. In this example, the separator 20 is continuously sent out from an original fabric 25 obtained by winding a long strip of separator 20 into a cylindrical shape, and a fuel gas channel and an oxidant gas channel are formed in the fed separator 20. Thereafter, the separator 20 is folded in half, and the membrane electrode assembly 10 is inserted between the folded anode separator 11 and cathode separator 12. Thereafter, the membrane electrode assembly 10 is sandwiched between the anode separator 11 and the cathode separator 12 to caulk the bent portion, and then a part of the bent portion is cut.

  As shown in FIG. 9, the fuel cell single cell 2 can be efficiently manufactured by continuously feeding the separator 25 from the raw fabric 25 and processing the separator 25 with a flow path as needed. It becomes.

It is a perspective view which shows the whole structure of a fuel cell stack. It is a perspective view of a fuel cell single cell. The manufacturing process of a fuel cell single cell is shown sequentially, and shows a separator forming process in which an anode separator and a cathode separator are integrated to form one separator. The manufacturing process of a fuel cell single cell is shown in order, and a two-fold process for folding a separator into two is shown. The manufacturing process of a fuel cell single cell is shown sequentially, and the separator opening process which opens an anode separator and a cathode separator leaving a bending part is shown. The manufacturing process of a fuel cell single cell is shown sequentially, and the abutting process which inserts and abuts the edge part of a membrane electrode assembly in a bending part is shown. The manufacturing process of a fuel cell single cell is shown sequentially, and the caulking process for caulking the bent portion is shown. It is a perspective view which shows an example of the separator which provided the insulating member in the part folded in half. It is a schematic process drawing which shows an example of the other manufacturing method of a fuel cell single cell.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Fuel cell stack 2 ... Fuel cell single cell 10 ... Membrane electrode assembly 11 ... Anode separator 12 ... Cathode separator 13 ... Solid polymer electrolyte membrane 14 ... Anode electrode 15 ... Cathode electrode 17 ... Caulking part 18 ... Seal member 19 ... Fuel gas flow path 20 ... Separator 21 ... Oxidant gas flow path 22 ... Bent part 24 ... Insulating member

Claims (8)

A membrane electrode assembly having at least a polymer electrolyte membrane;
An anode separator disposed on the anode side of the polymer electrolyte membrane;
A cathode separator disposed on the cathode side of the polymer electrolyte membrane,
The fuel cell single cell, wherein the anode separator and the cathode separator are composed of a single separator and are folded in two to sandwich the membrane electrode assembly. The fuel cell single cell according to claim 1,
A caulking portion is formed in the folded portion that is folded in half. A fuel cell single cell. The fuel cell unit cell according to claim 1 or 2,
A fuel cell single cell, wherein a part of the folded portion that is folded in half is cut. A fuel cell single cell according to any one of claims 1 to 3,
An insulating member is provided in the folded portion that is folded in half. A fuel cell unit cell. A separator forming step of forming a single separator by integrating the anode separator disposed on the anode side of the polymer electrolyte membrane and the cathode separator disposed on the cathode side;
Folding step of folding the separator in half, and arranging the anode separator and the cathode separator to face each other;
An abutting step of inserting and abutting the end portion of the membrane electrode assembly having at least the polymer electrolyte membrane into the folded portion that is folded in half;
The manufacturing method of the fuel cell single cell characterized by including the clamping process which clamps the said membrane electrode assembly with the said anode separator and the said cathode separator. It is a manufacturing method of the fuel cell single cell according to claim 5,
A fuel cell single cell manufacturing method comprising: a separator opening step of opening the anode separator and the cathode separator while leaving the bent portion after the bi-folding step. A method for producing a fuel cell single cell according to claim 5 or 6,
A method of manufacturing a fuel cell single cell, comprising a step of caulking the bent portion after the clamping step. It is a manufacturing method of the fuel cell single cell according to claim 7,
The manufacturing method of the fuel cell single cell provided with the cutting process which cut | disconnects a part of said bending part after the said clamping process.

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