JP2010073505A - Method for manufacturing end part sealing member, end part sealing member, method for manufacturing fuel cell, and fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a phosphoric acid type fuel cell wherein gas impermeability and corrosion resistance against electrolyte are enhanced. <P>SOLUTION: The method for manufacturing an end part sealing member 132 having gas impermeability and corrosion resistance against electrolyte includes a process in which a resin sheet 132b and a spacer material 132a are laminated in a plurality of pieces in order on a main face of a separator 142, and a process in which a distance between the spacer material 132a of the uppermost layer and the separator 142 is made closer while heating, and the resin sheet 132b and the spacer material 132a are heat-sealed. Furthermore, the fuel cell in which the above end part sealing member 132 is used is improved in reliability. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an end seal member manufacturing method, an end seal member, a fuel cell manufacturing method, and a fuel cell, and in particular, an end seal manufacturing method that constitutes a fuel cell, an end seal member that constitutes a fuel cell, The present invention relates to a method of manufacturing a fuel cell having an end seal member and a fuel cell having an end seal member.

  Phosphoric acid fuel cell (PAFC) has a phosphoric acid solution held in an electrolyte layer, and a fuel gas (for example, hydrogen) and an air gas (for example, oxygen) are continuously supplied to the fuel electrode and the air electrode, respectively. And the energy obtained by reacting them is electrochemically converted into electrical energy.

FIG. 6 is a perspective view of a unit cell of a phosphoric acid fuel cell.
A unit cell 200 constituting a fuel cell includes a porous substrate with ribs provided with electrode portions 211 and 212 constituting a counter electrode and gas flow paths 221a and 222a for supplying gas to the electrode portions 211 and 212, respectively. 221 and 222. Further, gas-impermeable end seal members 231 and 232 are disposed at both end portions of the porous substrates 221 and 222 on two sides facing in parallel with the gas flow paths 221a and 222a of the unit cell 200, respectively. The separators 241 and 242 which are gas shielding plates are arranged so as to seal the upper and lower surfaces.

  The electrode part 211 supplies electrons and ions to an external circuit (not shown) by separating electrons into ions and ions from constituent molecules of the gas supplied via the porous base material 221. In the electrode part 212, the gas supplied through the porous substrate 222, electrons from the external circuit, and ions from the electrode part 211 react. For example, in the electrode portion 211, hydrogen molecules constituting the gas are decomposed into electrons and hydrogen ions, and electrons are supplied to the external circuit and hydrogen ions are supplied to the electrode portion 212 side. In the electrode part 212, oxygen molecules from the porous substrate 222, electrons from the external circuit, and hydrogen ions from the electrode part 211 react to generate water.

  The porous base materials 221 and 222 are disposed in contact with the electrode portions 211 and 212, respectively, and are made of a porous material. The porous base materials 221 and 222 have gas flow paths 221a and 222a, and the gas taken in from the gas flow paths 221a and 222a is supplied to the electrode portions 211 and 212, respectively. The porous base materials 221 and 222 are disposed on the electrode portions 211 and 212 so that the gas passage directions of the gas passages 221a and 222a are orthogonal to each other.

  The end seal members 231 and 232 are configured by members having gas impermeability so that gases taken from the gas flow paths 221a and 222a are not mixed in the unit cell 200, and the gas flow paths 221a and 222a It is formed at each end portion of each of the two sides of the porous substrates 221 and 222 facing in parallel.

  The separators 241 and 242 are configured by carbon plates or the like that shield the gas taken in from the gas flow paths 221a and 222a, respectively, and are disposed on the porous base materials 221 and 222 and the end seal members 231 and 232, respectively. Yes.

A plurality of unit cells 200 configured as described above are stacked to form a fuel cell.
Moreover, in such a unit cell 200, by using an expanded graphite sheet for the end seal members 231 and 232, gas tightness is further improved to prevent gas leakage (see, for example, Patent Document 1). By setting the cross-sectional areas of the paths 221a and 222a to a predetermined ratio, the thickness of the unit cell itself can be reduced while maintaining the performance of the unit cell (see, for example, Patent Document 2).
Japanese Patent Laid-Open No. 2001-23654 Japanese Patent Application Laid-Open No. 7-6773

  In order to improve the gas impermeability more than the above Patent Documents 1 and 2, the present invention provides an end seal member manufacturing method and an end seal member with improved gas impermeability and corrosion resistance to an electrolyte, and An object of the present invention is to provide a method of manufacturing a fuel cell having such an end seal member and a fuel cell.

In order to achieve the above object, a method of manufacturing an end seal member constituting a fuel cell is provided.
Such an end seal member manufacturing method includes a step of sequentially laminating a plurality of resin sheets and spacer materials on the main surface of the separator, and a step of reducing the distance between the uppermost spacer material and the separator while heating. Have.

Moreover, the manufacturing method of a fuel cell has such a manufacturing method of an end seal member.
According to the manufacturing method of the end seal member and the manufacturing method of the fuel cell, a plurality of resin sheets and spacer materials are sequentially stacked on the main surface of the separator, and the distance between the uppermost spacer material and the separator is heated. By being shrunk, the end seal member and the fuel cell having such an end seal member are formed.

  In the end seal manufacturing method and the fuel cell manufacturing method, an end seal member having gas impermeability and corrosion resistance and a fuel cell with improved reliability are manufactured.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view for explaining the formation of the end seal member according to the embodiment by a pressing means.

  The pressing means 15 for forming the end seal member 132 used in the fuel cell includes a mounting table 151 and a pressing plate 152 disposed to face the mounting table 151. In such a pressing means 15, the object placed on a predetermined position of the placing table 151 is heated by a heating means (not shown) while the pressing plate 152 is lowered to press the object. Below, the specific formation method of the edge part sealing member 132 which is a target object is demonstrated.

  First, the separator 142 is mounted on the mounting table 151 of the pressing means 15. On the separator 142, a plurality of resin sheets 132b and spacer materials 132a are sequentially stacked and arranged at two positions with a predetermined interval.

Next, the pressing plate 152 is lowered, and the plurality of stacked spacer members 132a and resin sheets 132b are pressed while being heated by a heating means (not shown).
Since the resin sheet 132b is melted, the plurality of laminated spacer materials 132a and resin sheets 132b are heat-sealed with good adhesion. After heat sealing, the pair of end seal members 132 are formed by cooling.

  As described above, by heat-sealing the spacer material 132a and the resin sheet 132b laminated on the separator 142, the adhesion is improved, and the end seal member 132 having gas impermeability and corrosion resistance is formed. The In addition, the fuel cell having such an end seal member 132 is improved in reliability because leakage of fuel gas or the like is suppressed.

A fuel cell to which the end seal member 132 is applied will be described.
FIG. 2 is a perspective view of the fuel cell. The fuel cell 100 shown in FIG. 2 is configured by stacking two layers of unit cells 10.

  The unit cell 10 includes, on the fuel electrode side, a fuel electrode portion 111 and a porous substrate 121 having a gas flow path 121a for a fuel gas containing hydrogen molecules, which is disposed in contact with the fuel electrode portion 111. On the air electrode side, an air electrode part 112 and a porous base material 122 having a gas flow path 122a of air gas containing oxygen molecules arranged in contact with the air electrode part 112 are provided. Further, in these configurations, the end seal member 131 on the fuel electrode side and the end seal member 131 on the air electrode side are provided on both end portions of the porous substrates 121 and 122 on the two sides facing in parallel with the gas flow paths 121a and 122a. End seal members 132 are provided. Further, a fuel electrode side separator 141 and an air electrode side separator 142 which are gas shielding plates are laminated.

  The fuel electrode portion 111 is configured by laminating a fuel electrode substrate, a fuel electrode catalyst layer, and an electrolyte layer in order from the porous substrate 121 side. In addition, illustration of each structure of the fuel electrode part 111 is abbreviate | omitted.

  The fuel electrode substrate is made of, for example, a porous carbon plate. The fuel electrode base material divides the fuel gas supplied via the porous base material 121 into electrons and hydrogen ions, and supplies the electrons to an external circuit (not shown) and hydrogen ions to the air electrode 112 side. The fuel electrode catalyst layer is composed of, for example, a catalyst in which platinum fine particles are supported on carbon powder and Teflon (registered trademark), and promotes a chemical reaction on the fuel electrode base material. The electrolyte layer is configured by including a phosphoric acid solution in, for example, a silicified carbon substrate, and hydrogen ions from the fuel electrode base material pass therethrough.

  The porous substrate 121 is disposed in contact with the fuel electrode portion 111 and is made of a porous material. The porous base material 121 takes in a fuel gas containing hydrogen molecules from the gas flow path 121 a, and the fuel gas is supplied to the fuel electrode base material of the fuel electrode unit 111.

  The air electrode portion 112 is configured by laminating an air electrode base material, an air electrode catalyst layer, and an electrolyte layer in order from the porous base material 122 side. In addition, description of each structure of the air electrode part 112 is abbreviate | omitted.

  The air electrode substrate is made of, for example, a porous carbon plate. In the air electrode base material, oxygen molecules contained in the air gas supplied through the porous base material 122, electrons from the external circuit, and hydrogen ions from the fuel electrode base material react to generate water. Is done. As with the fuel electrode portion 111 described above, the air electrode catalyst layer promotes a chemical reaction on the air electrode base material, and the electrolyte layer is made of a phosphoric acid solution, so that hydrogen ions from the fuel electrode portion 111 are absorbed. pass.

  The porous base material 122 is disposed in contact with the air electrode base material of the air electrode portion 112 and is made of a porous material. The porous base material 122 is formed with a gas flow path 122a of air gas containing oxygen molecules, and the air gas taken in from the gas flow path 122a is supplied to the air electrode base material. In addition, the porous base material 122 is arrange | positioned so that the direction of a mutual flow path may orthogonally cross with respect to the porous base material 121. FIG.

  The end seal members 131 and 132 are provided at both end portions of the two sides of the porous base materials 121 and 122 facing in parallel with the gas flow paths 121a and 122a. The end seal members 131 and 132 are configured by laminating a plurality of resin sheets 131b and 132b and spacer materials 131a and 132a in order. The spacer members 131a and 132a are composed of the same members as the separators 141 and 142 described later.

  The separators 141 and 142 are made of graphitized carbon plates, have gas impermeability, and also have corrosion resistance to the electrolyte. In addition to such a member, special metals such as stainless steel and titanium having high corrosion resistance may be used. As described above, such members are also used for the spacer materials 131a and 132a. The separators 141 and 142 are laminated on the porous base materials 121 and 122 and the end seal members 131 and 132 on the fuel electrode side and the air electrode side, and not only prevent gas leakage but also cool the unit cell 10. It also has a role to play.

Next, another method for forming the end seal members 131 and 132 will be described.
FIG. 3 is a perspective view for explaining the formation of the end seal member using the expanded graphite sheet by the pressing means.

  The pressing means 150 for forming the end seal member 132 includes a mounting table 151 and a pressing plate 152 disposed to face the mounting table 151, as in FIG. Furthermore, an expanded graphite sheet 153 is newly arranged on the pressing surface of the pressing plate 152 in accordance with the size and the arrangement interval of the end seal member 132 to be formed. In such a press means 150, while pressing the target object placed at a predetermined position on the mounting table 151 by a heating means (not shown), the pressing plate 152 is lowered and pressed through the expanded graphite sheet 153. Below, the specific formation method of the edge part sealing member 132 which is a target object is demonstrated.

  First, the separator 142 is mounted on the mounting table 151 of such a press means 150. On the separator 142, a plurality of resin sheets 132b and spacer materials 132a are sequentially stacked and arranged at two positions with a predetermined interval.

  Next, the pressing plate 152 is lowered, the expanded graphite sheet 153 is disposed on the uppermost spacer material 132a, and the spacer material 132a and the resin sheet 132b are pressed by the pressing plate 152 while being heated by a heating means (not shown). As the heating temperature rises, the resin sheet 132b melts and the expanded graphite sheet 153 expands thermally. In addition to the pressing plate 152, the melted resin sheet 132b and the spacer material 132a are heat-sealed with good adhesion by pressing from the thermally expanded expanded graphite sheet 153, and the end of the fusion structure having gas impermeability. A part seal member 132 is formed.

  On the other hand, when only the pressing plate 152 is lowered by a predetermined distance to reduce the distance from the mounting plate 151 and the plurality of stacked spacer members 132a and resin sheets 132b are pressed while being heated, the resin as shown in FIG. The sheet 132b is thermally fused to the spacer material 132a. At this time, since the resin sheet 132b melts and softens, the pressure in the thickness direction from the resin sheet 132b decreases. Further, since the gap between the pressing plate 152 lowered by a predetermined distance and the mounting plate 151 is constant, the spacer material 132a and the resin sheet 132b cannot be further pressed, and the resin sheet 132b may leak out. There is. The end seal member 132 formed in this way may have reduced adhesion.

  Therefore, when the expanded graphite sheet 153 is disposed on the uppermost spacer material 132a, the expanded graphite sheet 153 thermally expands even after the gap between the pressing plate 152 and the mounting plate 151 becomes constant. The pressure from 152 can be compensated. For this reason, by using the expanded graphite sheet 153, the melted resin sheet 132b and the spacer material 132a are heat-sealed with good adhesion, and the end seal member 132 having a gas-impermeable structure can be reliably secured. It becomes possible to form.

  Further, the thickness of the expanded graphite sheet 153 can be set in advance according to the thermal expansion coefficient so that the expanded graphite sheet 153 has a desired expansion dimension at a predetermined heat fusion temperature. By doing so, the end seal member 132 can be controlled to a desired thickness, and excessive leakage of the melted resin sheet 132b can be prevented, resulting in insufficient fusion between the resin sheet 132b and the spacer material 132a. A decrease in gas impermeability can be suppressed.

Further, the end seal member 132 can be formed by arranging the expanded graphite sheet 153 as follows.
FIG. 4 is a front view for explaining the formation of the end seal member using the expanded graphite sheet by another pressing means.

In order to form the end seal member 132, the expanded graphite sheet 153 may be disposed on the opposite surface of the separator 142 on which the resin sheet 132b is formed (FIG. 4A).
Also in this case, the end plate sealing member 132 is formed in the same manner as described above by lowering the pressing plate 152 toward the mounting table 152 while heating and pressing the spacer material 132a and the expanded graphite sheet 153 as the uppermost layer. can do.

  Alternatively, the expanded graphite sheets 153a and 153b may be respectively disposed on the opposite surface of the separator 142 on which the resin sheet 132b is formed and the uppermost spacer material 132a (FIG. 4B).

  Also in this case, the end seal member 132 can be formed in the same manner as described above by lowering the pressing plate 152 toward the mounting table 152 while heating and pressing the expanded graphite sheets 153a and 153b.

Note that the end seal member 131 can also be formed in the same manner as in FIGS.
FIG. 5 is a perspective view for explaining the assembly process of the unit cell.

  A porous base material 122 having a separately formed gas flow path 122a is fitted into the separator 142 and end seal members 132 formed at two positions on the main surface of the separator 142 at a predetermined interval. The air electrode part 112 is formed on the main surface of the porous substrate 122.

  Similarly, on the fuel electrode side, a porous substrate having a gas flow path 121a with respect to the separator 141 and end seal members 131 formed at two positions on the main surface of the separator 141 at a predetermined interval. 121 is fitted, and the fuel electrode portion 111 is formed on the main surface of the porous substrate 121.

  The unit cells 10 are formed by bonding the cells formed in this way so that the flow paths of the gas flow paths 121a and 122a are orthogonal to each other, and the fuel cell 100 is configured by stacking a plurality of unit cells 10.

  In the fuel cell 100 formed as described above, the spacer materials 131a and 132a are the same graphitized carbon plates as the separators 141 and 142, and thus have excellent corrosion resistance to the electrolyte. If the carbon plate is too thick, it may be damaged during graphitization. However, since the spacer materials 131a and 132a are used in a thin state, damage during graphitization is suppressed. A plurality of such spacer materials 131a, 132a and resin sheets 131b, 132b are laminated and heated, and heat-sealed with good adhesion, thereby forming end seal members 131, 132 having gas impermeability and corrosion resistance. The Further, the end seal members 131 and 132 having a desired thickness can be formed by heat-sealing the resin sheets 131b and 132b to the spacer members 131a and 132a without excessively protruding. Dimensional defects can be suppressed. Therefore, the fuel cell 100 with improved production yield and increased reliability is provided.

Hereinafter, the formation of the end seal member 132 using the above method will be specifically described.
Note that the target thickness of the end seal member 132 to be formed is about 1.9 mm.
Further, as the separators 141 and 142, glassy carbon plates (SG-3 (manufactured by Showa Denko KK)) having dimensions of 130 mm in length, 130 mm in width, and 0.6 mm in thickness were used.

As the spacer materials 131a and 132a, the above glassy carbon plates having dimensions of 10 mm in length, 130 mm in width, and 0.6 mm in thickness were used.
As the resin sheets 131b and 132b, PFA sheets having dimensions of 8 mm long × 130 mm wide × 50 μm thick were used.

On the expanded graphite sheet 153, PF180 having dimensions of 10 mm in length, 130 mm in width, and 1.8 mm in thickness (made by Toyo Tanso Co., Ltd., bulk density: 0.65 g / cm ³ , thermal expansion coefficient (thickness direction): 1 × 10 ⁻⁶ / ° C.).

  The spacer plate 132a and the resin sheet 132b are pressed for 10 minutes while the pressing plate 152 is lowered toward the mounting table 151 and heated at 310 ° C. by the heating means. In addition, the pressure by the pressing plate 152 at this time was set to a relatively small 0.29 MPa.

When the temperature rises from room temperature (25 ° C.) to 310 ° C., the expanded graphite sheet 153 expands by about 0.05 mm (= 1.8 × (310−25) × 1 × 10 ⁻⁶ ) in the thickness direction. . Since the end sealing member 132 is pressed against the expanded expanded graphite sheet 153 by the pressing means 150 in which the expanded graphite sheet 153 is arranged, the thickness thereof is about 1.9 mm which is a target. . The fuel cell 100 having the end seal member 131 and the end seal member 132 formed in the same manner operated without causing gas leakage. This is because even if the pressure by the pressing plate 152 is weak, a sufficient adhesion is obtained between the resin sheets 131b and 132b and the spacer materials 131a and 132a by further applying pressure due to thermal expansion of the expanded graphite sheet 153. It is thought that it was fused.

  As described above, a plurality of spacer members 131a and 132a and resin sheets 131b and 132b are stacked and heated, and heat-sealed with good adhesion to end seal members 131 and 132 having gas impermeability and corrosion resistance. Is formed. Furthermore, the thickness of the end seal members 131 and 132 can be formed with a desired dimension, and the defective dimension of the end seal members 131 and 132 can be suppressed. Therefore, the fuel cell 100 with improved production yield and increased reliability is provided.

It is a perspective view for demonstrating formation by the press means of the edge part sealing member which concerns on embodiment. It is a perspective view of a fuel cell. It is a perspective view for demonstrating formation by the press means of the edge part sealing member using an expanded graphite sheet. It is a front view for demonstrating formation by the another press means of the edge part sealing member using an expanded graphite sheet. It is a perspective view for demonstrating the assembly process of a unit cell. It is a perspective view of the unit cell of a phosphoric acid type fuel cell.

Explanation of symbols

10 Unit cell 100 Fuel cell 111 Fuel electrode part 112 Air electrode part 121, 122 Porous base material 121a, 122a Gas flow path 131, 132 End seal member 131a, 132a Spacer material 131b, 132b Resin sheet 141, 142 Separator 150 Press Means 151 Mounting table 152 Press plate 153, 153a, 153b Expanded graphite sheet

Claims (12)

In the manufacturing method of the end seal member constituting the fuel cell,
A step of laminating a plurality of resin sheets and spacer materials in order on the main surface of the separator;
Reducing the distance between the spacer material of the uppermost layer and the separator while heating;
The manufacturing method of the edge part sealing member characterized by having. Disposing an expanded graphite sheet on either the surface of the uppermost spacer material or the opposite surface of the main surface of the separator;
Reducing the distance between the expanded graphite sheet and the other surface on which the expanded graphite sheet is not disposed, while heating;
The manufacturing method of the edge part sealing member of Claim 1 characterized by the above-mentioned. Disposing an expanded graphite sheet on the surface of the spacer material on the uppermost layer and the surface opposite to the main surface of the separator;
Reducing the distance between the pair of expanded graphite sheets while heating;
The manufacturing method of the edge part sealing member of Claim 1 characterized by the above-mentioned. In the end seal member constituting the fuel cell,
An end seal member in which a plurality of resin sheets and spacer materials are sequentially laminated and fused to the main surface of the separator.   The end seal member according to claim 4, wherein the separator and the spacer material are made of the same member.   6. The end seal member according to claim 5, wherein the same member is a graphitized carbon plate. In a method of manufacturing a fuel cell having an end seal member,
A step of laminating a plurality of resin sheets and spacer materials in order on the main surface of the separator;
Reducing the distance between the spacer material of the uppermost layer and the separator while heating to form the end seal member;
The step of disposing the porous substrate on the main surface of the separator, with the end of the porous substrate disposed in the electrode portion of the fuel cell adjacent to the end seal member;
A method for producing a fuel cell, comprising: Disposing an expanded graphite sheet on either the surface of the uppermost spacer material or the opposite surface of the main surface of the separator;
The step of forming the end seal member by shrinking the distance between the expanded graphite sheet and the other surface on which the expanded graphite sheet is not disposed, while heating;
The method for producing a fuel cell according to claim 7, comprising: Disposing an expanded graphite sheet on the surface of the spacer material on the uppermost layer and the surface opposite to the main surface of the separator;
Reducing the distance between the pair of expanded graphite sheets while heating to form the end seal member;
The method for producing a fuel cell according to claim 7, comprising: An electrolyte layer holding an electrolyte;
A fuel electrode part and an air electrode part provided with a catalyst layer, which are arranged across the electrolyte layer;
A pair of porous substrates respectively disposed in the fuel electrode part and the air electrode part, and supplying fuel gas and air gas to the respective electrode parts;
A pair of separators each having a pair of porous substrates disposed on the main surface;
A pair of end seal members disposed on the main surfaces of the pair of separators and adjacent to the ends of the pair of porous substrates, in which a plurality of resin sheets and spacer materials are sequentially laminated and fused;
A fuel cell comprising:   The fuel cell according to claim 10, wherein the separator and the spacer material are made of the same member.   12. The fuel cell according to claim 11, wherein the same member is a graphitized carbon plate.

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