JP4615266B2 - Polymer electrolyte fuel cell - Google Patents

Description

  The present invention relates to a polymer electrolyte fuel cell used for a portable power source, a power source for portable devices, a power source for electric vehicles, a home cogeneration system, and the like.

  A fuel cell using a polymer electrolyte membrane generates electric power and heat simultaneously by electrochemically reacting a fuel gas containing hydrogen and an oxidant gas containing oxygen such as air. This fuel cell includes a polymer electrolyte membrane that selectively transports hydrogen ions, and a pair of electrodes formed on both sides of the polymer electrolyte membrane, that is, an anode and a cathode. This is called an electrolyte membrane electrode assembly (MEA). The electrode is mainly composed of carbon powder carrying a platinum-based metal catalyst, and has a catalyst layer formed on both surfaces of the polymer electrolyte membrane, and an air permeability and electronic conductivity formed on the outer surface of the catalyst layer. It consists of a gas diffusion layer having both.

  Next, a polymer electrolyte membrane is sandwiched around the electrodes so that the fuel gas and oxidant gas (reactive gas) to be supplied do not leak out or the two kinds of reactive gases are mixed with each other. A sealing material such as a gasket is disposed. This sealing material is integrated with an electrode and a polymer electrolyte membrane and assembled in advance, and this is called an electrolyte membrane electrode sealing material assembly (MESA).

  Outside the MEA, a conductive separator plate that mechanically fixes the MEA and electrically connects adjacent MEAs to each other in series is disposed. The separator plate has a gas flow path for supplying reaction gas to the electrode surface and carrying away generated gas and surplus gas. Although the gas flow path can be provided separately from the separator plate, a method of providing a gas flow path by providing a groove on the surface of the separator plate is generally used.

  In order to supply the reaction gas to the groove, a jig for branching the piping for supplying the reaction gas to the number of separator plates to be used and connecting the branch destination directly to the groove on the separator plate is required. . This jig is called a manifold, and the type that connects directly from the reaction gas supply pipe as described above is called an external manifold. In addition, there is a type of this manifold called an internal manifold with a simplified structure. The internal manifold is a separator plate in which a gas flow path is formed with a through-hole, through the gas flow path to the hole, and a reaction gas is directly supplied from the hole.

  Since fuel cells generate heat during operation, it is necessary to cool them with cooling water or the like in order to maintain the cells in a favorable temperature state. Therefore, a flow path for cooling water is usually provided for every 1 to 3 cells. In general, a cooling water flow path is often provided on the back surface of the separator plate to form a cooling unit. These MEAs and separator plates are alternately stacked to obtain a stack by stacking 10 to 200 single cells. Then, the stack is sandwiched between end plates through current collector plates and insulating plates, and both ends are fastened with fastening bolts. Secure from. In this way, a polymer electrolyte fuel cell having a general structure is obtained.

  By the way, the sealing material used in the polymer electrolyte fuel cell as described above has high dimensional accuracy, sufficient elasticity, and sufficient tightening allowance to seal the reaction gas while contacting the separator plate and the electrode. It is necessary to have. For this reason, as a conventional sealing material, a sheet-like gasket made of resin or rubber, an O-ring shaped gasket made of rubber, or the like is used.

  Recently, for example, as disclosed in Patent Documents 1 and 2, it is necessary to seal a gasket in order to reduce the weight of the structural member, reduce the cost, and reduce the cost by reducing the stack fastening load. Attempts have been made to reduce the load. In addition, attempts have been made to make the sectional shape of the gasket not only an O-ring shape but also a triangular shape or a semicircular shape.

When using a gasket having an O-ring-shaped cross section and a cross-sectional area of a certain size, it has been attempted to configure the gasket on the separator plate side. However, since a large number of single cells are stacked and fastened in the stack, there is a problem that the gasket is insufficient to ensure a reliable sealing property.
When using an O-ring shaped gasket, the gasket is sealed by pressing the electrolyte membrane against the separator plate. Therefore, two seals are required between the anode (fuel electrode) and the electrolyte membrane and between the cathode (oxidant electrode) and the electrolyte membrane, that is, a gasket for the fuel gas seal and an oxidant gas seal. For this reason, there is a problem in that the size of the part that must be sealed increases.

  Furthermore, it is necessary to provide a groove for receiving an O-ring shaped gasket on the surface of the separator plate, and there is a restriction that the separator plate cannot be thinned in order to ensure the dimension of the groove. As a result, the volume of the stack is increased, the cost is increased, and the shape of the separator plate is complicated, which is a cause of deterioration of the yield when processing the separator plate. In order to solve such problems, attempts have been made to seal in a space-saving manner.

  Further, when assembling the stack, MESA or MEA is arranged on the separator plate, and further, the separator plate or the O-ring shaped gasket and the separator plate are arranged on the MEA. This process is repeated to obtain a stack. At that time, the O-ring shaped gasket or separator plate arranged on the MEA is generally arranged using a guide which is an assembling jig. However, each member has a dimensional error, and a clearance is required between the O-ring shaped gasket and the electrode from the viewpoint of easy assembly between the electrode and the O-ring shaped gasket or the separator plate. This clearance is also for ensuring workability or manufacturing yield.

If this clearance is small, it tends to be difficult to assemble the stack with high reliability. For example, an O-ring shaped gasket rides on a part of the electrode and bites it, resulting in poor sealing. Further, when the O-ring-shaped gasket comes into contact with the electrode, an excessive surface pressure is applied to the electrode, and the battery performance may be deteriorated due to damage to the electrolyte membrane or a decrease in durability.
Therefore, when the clearance between the O-ring shaped gasket and the electrode is reduced, unless the accuracy of the component dimensions is improved, the yield is reduced and the component cost is increased. In particular, when a molded separator plate is used, it is difficult to reduce the clearance between the O-ring shaped gasket and the electrode because there is a limit to the processing accuracy of a guide or the like used during assembly. For this reason, after obtaining a separator plate by molding, a guide portion is added by post-processing, which requires cost.

  On the other hand, if the clearance between the O-ring-shaped gasket and the electrode is increased in order to ensure assemblability, the reaction gas may flow into the clearance and the reaction gas may not flow into the gas flow path of the separator plate. Further, if the clearance for each unit cell varies due to an assembly error of the MEA and the O-ring shaped gasket, the pressure loss between the unit cells varies. At this time, the reaction gas corresponding to the pressure loss of each unit cell in the stack flows through each unit cell, so that the flow rate of the reaction gas varies. For this reason, the battery performance varies between the individual cells, and adverse effects such as a decrease in generated voltage, a decrease in durability, and a decrease in stability during low output operation occur. These symptoms were remarkable on the fuel gas side where the utilization rate of the reaction gas was relatively large.

Further, when a flat gasket is used, the volume occupied by the gasket can be reduced, but the above-described problems relating to the assembly of the stack and the problems relating to the clearance exist as in the case of the O-ring gasket. Furthermore, an excessive fastening force is required to ensure the surface pressure necessary for the seal. Therefore, it is difficult to reduce the weight, compactness, and cost of the stack fastening member.
JP-A-11-233128 JP 2002-141082 A

  Therefore, the present invention can stack single cells with high reliability when the stack is assembled, and can reduce the clearance between the sealing material and the electrode when the stack is fastened. It is an object of the present invention to provide a polymer electrolyte fuel cell having output characteristics.

A fuel cell according to the present invention includes a polymer electrolyte membrane, a pair of electrodes disposed on both sides of the electrolyte membrane, and a pair of conductive separators having a gas flow path that sandwiches the electrodes and supplies a reaction gas to the electrodes A pair of sealing means sandwiching the electrolyte membrane between the plate and the pair of separator plates, and maintaining airtightness between the electrode and the pair of separator plates,
The pair of sealing means is composed of a combination of a planar sealing member having a planar portion in contact with the electrolyte membrane in a planar shape and a linear sealing member having ribs in contact with the electrolyte membrane in a linear shape,
It said pair of sealing means is disposed along the periphery of the front Symbol pair of electrodes,
When the electrolyte membrane, the pair of electrodes, and the pair of separator plates are stacked and fastened, at least a part of the rib falls in the electrode direction.

In the fuel cell, the rib is configured such that when the electrolyte membrane, the pair of electrodes, and the pair of separator plates are stacked and fastened, the entire rib falls down in the electrode direction. It is preferable.
Further, as a specific aspect of the rib, a cross section of the rib in the stacking direction has a curved shape so that the rib approaches the electrode as it goes toward the center in the stacking direction, When the electrolyte membrane, the pair of electrodes, and the pair of separator plates are stacked and fastened, it is preferable that the rib bends and curves toward the electrode.

The rib is inclined to the electrode side, and when the electrolyte membrane, the pair of electrodes, and the pair of separator plates are stacked and fastened, the rib is preferably tilted to the electrode side.
It is preferable that the rib has a circular portion at a tip in contact with the electrolyte membrane in a cross section in the stacking direction, and the diameter of the circular portion is substantially more than half of the thickness of the electrode. .

The cross section of the rib in the stacking direction is preferably linear .
Preferably before Symbol pair of sealing means has an adhesive layer.
It is preferable that the adhesive layer has acid resistance.

  According to the present invention, it is possible to secure a sealing property, suppress a decrease in battery performance, facilitate assembling, make a stack member compact by reducing a fastening force, and a separator plate by making a space necessary for sealing compact. Thinning is possible. Further, the guide portion provided on the separator plate can be roughened, and it is not necessary to process the guide portion after the separator plate is formed. This makes it possible to improve the reliability of the obtained fuel cell, improve the yield during mass production, make it compact, and significantly reduce costs.

The point of the fuel cell according to the present invention is that the pair of sealing means is composed of a planar sealing member and a linear sealing member.
The planar sealing member is mainly composed of a planar portion substantially parallel to the surface direction of the separator plate. Further, the linear seal member is mainly composed of a rib (lip-shaped portion) extending in a direction intersecting with the surface direction of the separator plate, and the linear seal portion at the tip of the rib is substantially on the planar seal member side. Sealing is performed by contacting the wire linearly.

  And the said rib has the characteristic in the point which has the shape which falls to the electrode side at the time of the said linear seal member fastening. Therefore, when a fuel cell is manufactured by laminating a pair of sealing means, a separator plate, and an electrode and fastening a stack, the rib is substantially sandwiched between the separator plate and the electrolyte membrane and fastened. Go. At this time, the rib develops a sealing property while falling toward the electrode side, and when the fastening is completed, a gap (clearance) between the linear sealing member and the electrode is blocked by the rib that is pressed and falls toward the electrode side. It is. When assembling each member that has not yet been fastened, a clearance is secured so that the members of the separator plate, the sealing means, and the electrode do not interfere with each other, so that an assembly failure such as a seal failure caused by the interference of each member does not occur.

  That is, the linear sealing member in the present invention has a shape that ensures a sufficient clearance between the linear seal part and the electrode before being sandwiched between the electrode and the separator plate, After being sandwiched between and tightened, at least a part of the rib of the linear seal member falls toward the electrode side in a state having a seal tightening margin, and enters the gap between the linear seal member and the electrode. It enters and reduces the clearance.

  By using such a pair of sealing means, a stable sealing property can be obtained, a space required for sealing can be reduced, and a stack fastening load can be reduced. Also, when assembling the stack, especially the clearance between the linear seal member and the electrode can be secured sufficiently, and when the stack is fastened, the rib of the linear seal member is bent toward the electrode side or falls down, so that it is more than that during assembly. Clearance can be reduced. Thereby, it is possible to suppress the reaction gas from flowing into the clearance, and stable power generation performance can be obtained.

  That is, according to the present invention, it is possible to ensure sealing performance by ensuring highly reliable assembly, reduce outflow of reaction gas to the clearance by reducing clearance, and improve battery performance associated therewith. Battery stacking by eliminating post-processing of separator plates by reducing the accuracy of guide parts required for separator plates during assembly and improving yield during manufacturing, as well as reducing costs and space occupied by seal members It is possible to reduce the body volume, reduce the stack fastening force, reduce the weight, reduce the size, and reduce the cost.

  In the linear sealing member, it is preferable that the cross section of the rib including the linear sealing portion in the stacking direction has a convex shape on the electrode side and a concave shape on the side opposite to the electrode. In this case, since the rib has such a cross-sectional shape, when a fastening load is applied to the rib from the stacking direction at the time of stack fastening, the rib contacts the electrolyte membrane linearly and bends and curves toward the electrode side. . That is, the linear seal member is fastened between the stacks while the rib is curved in a convex shape.

  Therefore, the sealing performance is ensured by the reaction force to the separator plate and the electrolyte membrane based on the elasticity of the linear seal member. Moreover, even if a sufficient clearance between the linear seal member and the electrode is ensured, the gap between the linear seal member and the electrode can be reduced by the curved rib protruding in the electrode direction. By reducing the gap, the fuel gas or oxidant gas that has flowed without reacting with the electrode through the gap can be flowed into the flow path of the separator plate that should flow.

  As a result, the same effect as described above can be obtained. That is, it is possible to ensure sealing performance by ensuring highly reliable assembly, reduce outflow of reaction gas to clearance by reducing clearance, and improve battery performance associated therewith. In addition, the battery is abolished by eliminating post-processing of the separator plate by reducing the accuracy of the guide part necessary for the separator plate during assembly, improving the yield during manufacturing, and reducing the cost associated with it, and reducing the space occupied by the seal member. It is possible to reduce the volume of the laminated body and to reduce the weight, the size, and the cost by reducing the stack fastening force.

Further, the rib that falls to the electrode side at the time of fastening in the linear seal member has a circular portion at the tip in the cross section in the stacking direction, and the diameter of the circular portion is substantially the thickness of the electrode. It is preferable that it is more than half. Note that the tip portion corresponds to a line seal portion in linear contact with the electrolyte membrane.
Thereby, when the stack is fastened, the reaction force generated by the linear sealing member against the separator plate or the electrolyte membrane is increased, and it is possible to secure a more stable sealing property. That is, when the stack is fastened with the linear seal member sandwiched between the separator plate and the electrolyte membrane, the rib is curved, tilted, or collapsed toward the electrode side, filling the gap, and The circular portion is compressed by being sandwiched between the separator plate and the electrolyte membrane. At that time, since the circular portion has a diameter of more than half of the electrode thickness, a larger reaction force is exerted when compressed by a predetermined amount. Therefore, the sealing performance is improved, and a more stable seal can be obtained.

  Examples of the material constituting the planar sealing member and the linear sealing member include fluorine rubber, polyisobrene, butyl rubber, ethylene propylene rubber, silicone rubber, nitrile rubber, thermoplastic elastomer, liquid crystal polymer, polyimide resin, and polyether ether ketone resin. , Polyetherimide resin, polyphenylene sulfide resin, terephthalamide resin, polyether sulfone resin, polysulfone resin, syndiotactic polystyrene resin, polymethylpentene resin, modified polyphenylene ether resin, polyacetal resin, polypropylene resin, fluorine resin, and polyethylene Examples include terephthalate resin. These may be used alone or as a composite of two or more.

It is preferable that an adhesive layer is formed on a portion in contact with the electrolyte membrane and / or a portion in contact with the separator plate of the planar sealing member and the linear sealing member.
For example, the tip end portion (line seal portion) of the rib in the above-described linear seal member is pressed against the electrolyte membrane to ensure sealing performance. At this time, since the adhesive layer is formed at the tip of the rib in contact with the electrolyte membrane, a stable sealing property can be obtained by the adhesive force of the adhesive layer even if the reaction force of the seal member itself is weak.

Examples of the material constituting the adhesive layer include a copolymer of styrene and ethylene butylene, polyisobutylene, ethylene propylene rubber, and butyl rubber. These may be used alone or as a composite of two or more.
Moreover, in order to ensure the sealing performance of the sealing member for a long time, the adhesive layer is preferably acid resistant. For example, when an electrolyte membrane having hydrogen ion conductivity is used, the electrolyte membrane portion in contact with the adhesive layer exhibits acidity in a state where the ion conductivity is expressed. Therefore, in order for the adhesive layer portion in contact with the electrolyte membrane to obtain a stable sealing property over a long period of time, it is desirable that the adhesive layer has acid resistance.
Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1
A front view of the anode side separator plate is shown in FIG. 1, and a rear view thereof is shown in FIG.
The conductive anode-side separator plate 10 includes a pair of fuel gas manifold holes 12, a pair of oxidant gas manifold holes 13, a pair of cooling water manifold holes 14, a pair of spare manifold holes 15, and 4. It has a bolt hole 11 for fastening.
A surface of the anode separator plate 10 facing the anode is provided with a gas flow path 12b that is connected to a pair of fuel gas manifold holes 12 and supplies fuel gas to the anode. The gas flow path 12b is composed of four grooves.

  On the back surface of the separator plate 10, a cooling water flow path 14 b that connects the pair of cooling water manifold holes 14 is provided. The flow path 14b is composed of six parallel grooves. O-ring grooves 12a and 13a for installing O-rings are provided so as to surround each pair of fuel gas manifold holes 12 and oxidant gas manifold holes 13. Further, an O-ring groove 14a surrounding the cooling water manifold hole 14, the spare manifold hole 15, and the cooling water flow path 14b is provided.

A front view of the cathode separator plate is shown in FIG. 3, and a rear view thereof is shown in FIG.
The cathode separator plate 20 having conductivity includes a pair of fuel gas manifold holes 22, a pair of oxidant gas manifold holes 23, a pair of cooling water manifold holes 24, a pair of spare manifold holes 25, and 4. There are one fastening bolt hole 21.

On the surface of the cathode-side separator plate 20 facing the cathode, there is provided a gas flow path 23b that communicates with the pair of oxidant gas manifold holes 23 and supplies the oxidant gas to the cathode. The gas flow path 23b is composed of seven grooves.
On the back surface of the separator plate 20, a cooling water flow path 24 b that communicates with the pair of cooling water manifold holes 24 is provided. The flow path 24b is composed of six parallel grooves.

Here, FIG. 5 shows a front view of a linear seal member used as the anode side seal member, and FIG. 6 shows a cross-sectional view taken along line X ₁ -X _{2 in} FIG. 7 shows a front view of a planar sealing member used as the cathode side sealing member, and FIG. 8 shows a cross-sectional view taken along line Y ₁ -Y _{2 in} FIG. The combination of the linear sealing member and the planar sealing member is a pair of sealing means that is the greatest feature of the present invention. The X ₁ -X ₂ line cross section and the Y ₁ -Y ₂ line cross section are cross sections in the stacking direction of the fuel cells.

  As shown in FIG. 6, the linear seal member 30 to be bonded onto the anode side separator plate 10 is a linear base seal member 36 having a film 4a made of polyimide and a rib (lip-shaped portion) 36a on one surface thereof. And an adhesive layer 5a formed on the other surface and adhered to the anode separator plate 10.

  The rib 36 a has a tip portion 36 b that is in linear contact with the polymer electrolyte membrane and has a substantially circular shape, and is provided along the base seal member 36. The rib 36a has a linear shape in the pressure contact direction (stacking direction) of the stacked battery and is bent toward the electrode. The distal end portion 36b linearly abuts on a cathode-side planar sealing member, which will be described later, through the electrolyte membrane. The diameter of the circle of the tip portion 36b is set to 1 mm, which is larger than the thickness of the electrode.

  As shown in FIG. 5, the linear seal member 30 includes a first anode-side seal portion that surrounds the outer periphery of the gas flow path 12 b and the pair of fuel gas manifold holes 12 in the anode-side separator plate and constitutes one closed loop. And manifold hole seal portions 33a, 34a, and 35a that independently surround the oxidant gas manifold hole 13, the cooling water manifold hole 14, and the spare manifold hole 15, respectively. Further, the base seal member 36 includes seal portions 38c and 38d surrounding both sides of the communication gas flow path 23b in the cathode side separator plate 20 described above.

  The linear seal member 30 includes an electrode seal portion 37 surrounding the anode, a manifold hole seal portion 32a surrounding the outer half of the fuel gas manifold hole 32, the electrode seal portion 37, and the manifold hole seal portion 32a. The seal portions 38a and 38b communicate with each other and surround both sides of the gas flow path 12b.

Further, the linear seal member 30 includes a seal part 39a connecting the fuel gas manifold hole seal part 32a and the oxidant gas manifold hole seal part 33a, the fuel gas manifold hole seal part 32a and the cooling water manifold hole seal part. 34a, a seal portion 39b connecting the oxidant gas manifold hole seal portion 33a and the spare manifold hole seal portion 35a, a cooling water manifold hole seal portion 34a and the spare manifold hole seal portion 35a. It has the seal part 39d to tie.
The film 4a and the pressure-sensitive adhesive layer 5a have the same shape as the base seal member 36, and are superposed to form the anode-side linear seal member 30.

  On the other hand, as shown in FIG. 8, the cathode-side planar sealing member 40 bonded to the cathode-side separator plate 20 includes a polyimide film 4b and a flat base sealing member 46 formed on one surface thereof. And an adhesive layer 5b that is formed on the other surface and adheres to the separator plate.

The film 4b and the adhesive layer 5b include a fuel gas manifold hole 42, an oxidant gas manifold hole 43, a cooling water manifold hole 44, and a spare manifold hole 45 corresponding to each manifold hole in the cathode side separator plate 20. In addition, a portion (electrode installation portion) 47 having a bolt hole 41 and corresponding to the cathode is cut out.
The cathode-side base seal member 46 is flat and has the same shape as the film 4b and the adhesive layer 5b.

The anode-side base seal member 36 is bonded to the anode-side separator plate 10 by bonding the surface on the adhesive layer 5a side of the anode-side linear seal member 30 to the surface of the anode-side separator plate 10 facing the anode. Fixed to.
On the other hand, the cathode-side base seal member 46 is bonded to the cathode-side separator plate 20 by adhering the surface on the adhesive layer 5b side of the cathode-side planar sealing member 40 to the surface of the cathode-side separator plate 20 facing the cathode. Fixed to.

Then, the cathode-side planar sealing member 40 and the anode-side linear sealing member 30 are sandwiched between both separator plates through an electrolyte membrane, and are sealed by pressure contact.
The MEA composed of a pair of electrodes and an electrolyte membrane is sandwiched between the anode-side separator plate 10 provided with the anode-side linear sealing member 30 and the cathode-side separator plate 20 provided with the cathode-side planar sealing member 40. A single battery is constituted by the above. In this case, the area of each electrode is smaller than the area of the electrolyte membrane, and the electrode is located at the center of the electrolyte membrane. Therefore, the electrolyte membrane is exposed around the MEA. This exposed portion is sandwiched between the linear seal member 30 and the planar seal member 40.

Generally, a unit cell is assembled using a predetermined assembly jig with a guide pin raised. An example of the assembly procedure is shown below.
First, the cathode-side separator plate 20 provided with the cathode-side planar sealing member 40 is placed on an assembly jig. Next, the MEA is disposed on the cathode separator plate 20 along the guide pins. Further, the anode side separator plate 10 provided with the anode side linear seal member 30 is disposed on the MEA.

  When assembling the unit cell by the procedure as described above, when assembling the anode side separator plate 10, the positional relationship between the MEA and the linear seal member 30 on the anode side cannot be visually confirmed. Therefore, the linear seal member 30 on the anode side may be slightly shifted. However, if the anode-side linear seal member 30 of the present embodiment is used, a sufficient clearance is provided between the MEA and the electrode seal portion 37 in the anode-side linear seal member 30 when the unit cell is assembled. Can be provided. For this reason, the linear seal member 30 on the anode side does not ride on the MEA, and the sealing performance can be secured stably.

  Further, when a stack is formed by stacking a plurality of single cells, when the stack is fastened, the rib 36a bent to the electrode side in the linear seal member 30 on the anode side is bent to the anode side in the MEA, and the anode The clearance between the electrode seal portion 37 that surrounds the anode and the anode in the MEA is reduced. For this reason, when the stack is used, the outflow of the reaction gas to the clearance can be reduced, and stable power generation performance can be obtained.

In the anode-side linear seal member 30 having the above-described configuration, the anode and the oxidant gas manifold hole 33 are separated from each other by the manifold hole seal portion 33a and the electrode seal portion 37. The anode and the manifold hole 33 may be separated only by the manifold hole seal portion 33a or the electrode seal portion 37.
The cathode-side flat seal member 40 having the above-described configuration has a shape that covers the entire main surface of the cathode-side separator plate 20 other than the portions corresponding to the cathode and each manifold hole, but the anode-side linear seal member You may comprise only the part corresponding to 30. FIG.

The linear seal member and the planar seal member described above have portions that do not correspond to each other when the stack is fastened. For example, in the linear seal member 30 shown in FIG. 5, the manifold hole seal portion 32a surrounds only half of the fuel gas manifold hole 32, and there is a seal member between the fuel gas manifold hole 32 and the anode. not exist. In this nonexistent portion, the linear seal member does not correspond to the planar seal member. However, when forming the stack, the elastic sealing member is pressed by the two separator plates with an appropriate pressure. Therefore, even if the two sealing members do not correspond to each other, one of the sealing members is directly connected to the separator plate. It can seal by contacting.
Further, a member such as a cover plate may be provided in the non-existing portion, and the member may be sealed in correspondence with the planar sealing member. For example, a cover plate that covers the upper side of the gas flow path 12b may be provided at a position corresponding to the cathode-side planar seal member 40 between the seal portions 38a and 38b in FIG.

In addition, the cross-sectional shape of the rib of the linear sealing member 30 in the anode side separator plate 10 of Embodiment 1 is not limited to the shape of FIG. As shown in FIGS. 11 and 12, it may be shaped like ribs 66a and 76a having tip portions 66b and 76b in linear contact with the electrolyte membrane. The ribs 66a and 76a are inclined to the electrode side with respect to the stacking direction (pressure contact direction) of the stack, and are configured to fall down to the electrode side (left side of the ribs 66a and 76a) when the stack is fastened.
At this time, the inclination angle after the fastening of the ribs 66a and 76a (the angle tilted between before the falling (dotted line) and after the falling (solid line) shown on the right side of the figure) is θ, and the length of the ribs 66a and 76a is L. Then, it is possible to reduce the clearance between the electrode and the seal member by Lsin θ.

Further, the cross-sectional shape of the rib tip portion 36b is substantially circular, and in this embodiment, the diameter is equal to or greater than the thickness of the electrode. Power is obtained and a stable seal can be secured.
It has been found that when the diameter of the circular cross-sectional shape of the tip end portion 36b of the rib is changed to have a diameter more than half of the electrode thickness, a stable sealing property can be easily obtained. Usually, when the electrode is pressed with the separator plate, the contact resistance between the electrode and the separator plate is reduced, and in order to output the obtained battery voltage effectively, the electrode is fastened with a surface pressure of about 10 kgf / cm ² . At this time, it was found that the electrode was compressed to almost half the initial thickness. For this reason, it has been found that if the diameter of the tip 36b of the rib is more than half of the initial electrode thickness, the reaction force increases at the time of fastening and the sealing performance is improved.

  Further, when the diameter of the tip 36b of the rib is 3 times or more of the initial thickness of the electrode, the sealing performance is obtained, but the contact resistance between the separator plate and the electrode increases, so that the output of the laminated battery The voltage tended to decrease. For this reason, it has been found that the diameter of the tip 36b of the rib is preferably less than three times the initial electrode thickness.

Embodiment 2
Next, FIG. 9 shows a front view of a linear seal member on the anode side according to another embodiment, and FIG. 10 shows a sectional view taken along line Z ₁ -Z _{2 in} FIG.
The anode-side linear seal member 56 of the present embodiment includes only a rib-shaped (lip-shaped) seal member 56a corresponding to the rib 36a in the anode-side linear seal member 30 described above with reference to FIGS. Composed.
Further, the linear seal member 56 on the anode side of the present embodiment is provided at a position corresponding to the electrode seal portion 37 of the linear seal member 30 and the manifold hole seal portions 33a, 34a, and 35a shown in FIG. A rib-like seal member 56a is provided. And the rib-shaped sealing member 56a is provided in the seal parts 52a, 53a, 54a, 55a, 57, 58a and 58b in FIG.

  The rib-shaped sealing member 56a has a shape bent toward the electrode side with respect to the stacking direction (pressure contact direction) in the stack, and has tip portions 57a and 57b that are in linear contact with the separator plate and the electrolyte membrane, respectively. When the stack is fastened, the rib-like seal member 56a is bent and curved in the electrode direction, the tip portion 57a is fixed to the separator plate, and the tip portion 57b is a flat surface on the cathode side to be described later via the electrolyte membrane during battery assembly. Abuts linearly on the shape seal member.

Further, in the linear seal member 56 on the anode side in the present embodiment, a thin plate-like seal is provided at a position corresponding to the seal portions 38c, 38d, 39a, 39b, and 39c in the linear seal member 30 in the first embodiment. Members 56b, 58c, 58d, 59a, 59b, and 59c are provided, and the rib-shaped seal members are connected and integrated.
By using the more compact anode-side linear seal member of the present embodiment and the cathode-side seal member of the first embodiment in combination, the same effects as those of the first embodiment can be obtained and an excellent seal can be obtained. Sex can be secured.

The shape of the rib-like seal member on the anode side separator plate of the second embodiment is a linear shape having tip portions 87a and 87b in contact with the electrolyte membrane and the anode side separator plate 10 at both tip portions as shown in FIG. The rib-like seal member 87 may be used.
In this case, the distal end portion 87b is fixed to the anode-side separator plate 10 with an adhesive, and the distal end portion 87a is located on the electrode side (left side of the rib-shaped seal member 87) with respect to the distal end portion 87b. That is, the rib-shaped sealing member 87 is inclined toward the electrode on the anode-side separator plate 10. For this reason, the rib-shaped seal member 87 can reduce the clearance between the electrode and the rib-shaped seal member by falling to the electrode side with the tip end portion 87b as a fulcrum during stack fastening.

For the adhesive, for example, a copolymer of styrene and ethylene butylene can be used. After applying a toluene solution containing a copolymer of styrene and ethylene butylene to a predetermined position of the seal member, the solvent toluene is removed in a drying furnace at 50 ° C., thereby forming an adhesive layer on the seal member. And a sealing member can be fixed to a separator board by sticking this adhesion layer to a separator board.
Hereinafter, embodiments of the present invention will be described in detail.

Example 1
(I) Production of Separator Plate An anode-side separator plate 10 shown in FIGS. 1 and 2 of Embodiment 1 and a cathode-side separator plate 20 shown in FIGS. 3 and 4 are produced by machining using an isotropic graphite plate. did. At this time, the thickness of the separator plate was 3 mm, and the grooves of the gas channel and the cooling water channel were set to a pitch of 3 mm and a groove width of 1.5 mm.

(Ii) Production of Seal Member A linear seal member 30 and a planar seal member 40 provided with the same adhesive layer as in the first embodiment shown in FIGS. 5 to 8 were produced.
Polyimide films 4a and 4b with a thickness of 100 μm are placed on the mold, the mold is tightened, and fluoro rubber (DuPont's fluoro rubber, Viton) is injection molded under the conditions of a temperature of 200 ° C. and an injection pressure of 150 kgf / cm ^2. Thus, predetermined base seal members 36 and 46 were formed on the polyimide films 4a and 4b. Secondary crosslinking was performed at 200 ° C. for 10 hours. Thereafter, adhesive layers 5a and 5b made of butyl rubber and having a thickness of 25 μm were transferred and bonded onto the polyimide films 4a and 4b, and the surfaces of the adhesive layers 5a and 5b were covered with a release film made of polypropylene.

At this time, the base seal member 36 made of fluororubber had a thickness of 125 μm and a width of 3 mm. Further, the rib 36a in the electrode seal portion 37 surrounding the anode of the base seal member 36 was formed integrally with the base seal member 36 at the time of the injection molding, and was provided at a position 0.7 mm from the tip portion on the electrode side. Further, the rib 36a is provided with a radius of curvature of 2.5 mm and an opening angle of 35 ° in a direction perpendicular to the base seal member 36. The ribs 36a other than the electrode seal portion 37 were provided at the center of the base seal member 36 having a width of 3 mm.
On the other hand, the thickness of the base seal member 46 of the planar seal member 40 on the cathode side was set to 125 μm. The fuel gas, oxidant gas, cooling water and spare manifold holes 42 to 45, the fastening bolt holes 41, and the portions facing the electrodes in the planar seal member 40 were removed with a punching die.

  The linear sealing member 30 and the planar sealing member 40 provided with the adhesive layers 5a and 5b obtained above were placed on the separator plates 10 and 20, respectively, and pressed by hot pressing. The conditions for hot pressing were a temperature of 100 ° C., a press load of 2000 kgf, and a pressurization time of 1 minute.

(Iii) Preparation of MEA Platinum particles having an average particle diameter of about 30 mm were supported on an acetylene black carbon powder at a weight ratio of 4: 1 to obtain a catalyst powder for an electrode. The catalyst powder dispersed in isopropanol and the perfluorocarbon sulfonic acid powder dispersed in ethyl alcohol were mixed to obtain an electrode paste. Using this electrode paste as a raw material, a catalyst layer was formed on one surface of a 250 μm thick carbon non-woven fabric by screen printing to obtain an electrode. At this time, the amount of platinum contained in the catalyst layer after forming the catalyst layer 0.5 mg / cm ^2, the amount of perfluorocarbon sulfonic acid was 1.2 mg / cm ^2.

The above electrodes were used as the anode and cathode. That is, the anode and cathode have the same configuration. An electrolyte membrane electrode assembly (MEA) is formed by sandwiching a hydrogen ion conductive polymer electrolyte membrane (Nafion 117 manufactured by DuPont) with a pair of electrodes having an area of 100 cm ² with the printed catalyst layer inside and hot pressing. Was made. As the hydrogen ion conductive polymer electrolyte membrane, a perfluorocarbon sulfonic acid thinned to a thickness of 25 μm was used.
The size of the electrolyte membrane is the same as the size of the separator plate described later, and the electrolyte membrane has holes corresponding to a pair of fuel gas manifold holes, cooling water manifold holes, and oxidant gas manifold holes in the separator plate. It was formed by a punching die.

(Iv) Assembling the laminated battery The anode-side separator plate 10 provided with the anode-side linear seal member 30 and the cathode-side separator plate 20 provided with the cathode-side planar seal member 40 obtained above. A unit cell was constructed by sandwiching an MEA having an electrode area of 100 cm ² . At this time, the O-ring 3 was installed in the O-ring grooves 12 a to 14 a of the anode side separator plate 10. When the single cells are stacked, the surface of the separator plate 10 having the cooling water flow path 14b and the surface of the adjacent single cell separator plate 20 having the cooling water flow path 24b face each other. In this way, a cooling unit was provided.

The procedure for assembling the cell will be described below.
A predetermined assembling jig with a guide pin placed thereon was placed, and a cathode-side separator plate 20 provided with a cathode-side planar sealing member 40 was placed thereon. Next, MEA was installed along the guide pin. At that time, the MEA was carefully assembled to the cathode-side separator plate 20 so that the cathode of the MEA would not run on the peripheral edge of the electrode installation portion 47 of the planar seal member 40. A clearance is required between the guide pins installed on the assembly jig and these members to be assembled.

The clearance between the cathode in the MEA and the planar sealing member 40 on the cathode side was secured at 0.25 mm on one side. For this reason, the clearance between the separator plate 20 and the guide pin could be set to 0.2 mm. In addition, since the size of the MEA greatly changes depending on the humidity during assembly, it is necessary to provide a large clearance between the MEA and the guide pin. In order to assemble the MEA stably, the clearance between the guide pin and the MEA required 1 mm.
After installing the MEA, the anode-side separator plate 10 provided with the linear seal member 30 on the anode side was assembled. At this time, a clearance of 0.7 mm was ensured between the anode and the electrode seal portion 37 in the base seal member 36. Since the separator plate 10 is opaque and the assembled state of the anode side separator plate 10 to the MEA cannot be visually observed, the anode side separator plate 10 was assembled according to the guide pins.

By repeating the above assembly process, 50 unit cells are stacked, end plates made of stainless steel are arranged on both ends of the obtained stack via current collecting plates and insulating plates, and a fastening load of 600 kgf is applied by a fastening rod. A fuel cell was fabricated by fastening the stack at This fuel cell was designated as cell A. After the fastening, the rib 36a of the electrode seal portion 37 is curved toward the anode side, so that there is almost no clearance between the anode and the electrode seal portion 37. At this time, as a result of confirming the surface pressure of the MEA and the separator plate with the pressure sensitive paper, the surface pressure applied to the MEA was 10 kgf / cm ² . As a result, the reaction force in the seal member was 100 kgf, and it was found that the battery A can be configured with a sufficiently low fastening force.

The battery A was checked for gas leaks. The outlet side manifold hole was closed, and He gas was introduced from the inlet side manifold hole at a pressure of 0.5 kgf / cm ² , and the inflow gas flow rate at that time was examined. There were no gas leaks on the air side, the fuel gas side, and the cooling water side, and it was confirmed that the battery A had no problem in fluid sealability.

<< Comparative Example 1 >>
A laminated battery B was produced in the same manner as in Example 1 except that a conventional flat gasket was used instead of the anode-side linear seal member and the cathode-side planar seal member in Example 1. In addition, as a flat gasket, the thing which affixed the 75-micrometer-thick silicone rubber sheet on both surfaces of the 100-micrometer-thick PET sheet | seat was used. The assembly of the members was performed in the same procedure using the assembly jig as in Example 1. At this time, the clearance between the flat gasket and the electrode was 0.25 mm on the anode side and the cathode side, respectively.

The battery B was checked for gas leakage under the same conditions as in Example 1. Since the fastening load was 4000 kgf and the surface pressure applied to the MEA was 10 kgf / cm ² , the fastening was set to 4000 kgf. As a result, in some of the cells, an external leak of gas or a cross leak from the oxidant gas side to the fuel gas side, or both occurred, resulting in poor sealing.

<< Comparative Example 2 >>
Battery C was produced in the same manner as in Comparative Example 1 except that the clearance between the flat gasket and the anode and cathode was 0.5 mm. The assembly of the members was performed in the same procedure using the assembly jig as in Example 1.
The battery C was subjected to a gas leak check under the same conditions as in Example 1. Since the fastening load was 4000 kgf and the surface pressure applied to the MEA was 10 kgf / cm ² , the fastening was set to 4000 kgf. As a result, it was confirmed that there was no gas leak on the oxidant side, the fuel gas side, and the cooling water side, and there was no problem in the fluid sealability as a laminated battery.

  After performing a leak check, the batteries A to C of Example 1 and Comparative Examples 1 and 2 were disassembled and the assembly condition was confirmed. In any of the batteries, the anode in the MEA was assembled with a slight shift from the center of the linear seal member on the anode side. However, in the batteries A and C of Example 1 and Comparative Example 2, there was a portion that sealed the periphery of the electrode. It was found that it was possible to ensure a sufficient sealing property during assembly because it was outside the electrode with a sufficient margin. On the other hand, in the battery B of Comparative Example 1, the electrodes were similarly displaced. However, it was found that when even a part of the electrodes climbs onto the gasket, the sealing performance is impaired and a sealing failure occurs.

When assembling the unit cell, after installing the MEA, the anode separator plate is assembled. At this time, it is desirable that the MEA anode is placed at the center of the anode-side linear seal member, but positional deviation occurs due to accumulation of assembly jig clearance, MEA dimensional error, and separator plate dimensional error.
If the degree of assembly between the anode and the linear seal member on the anode side can be visually confirmed, stable assembly is possible. However, the separator plate is opaque and cannot be visually observed, and is assembled according to the guide pins.

  In the case of a conventional flat gasket, the electrode rides on the gasket in the vicinity of the upper limit of the positional deviation assumed, and the sealing performance cannot be secured. If the clearance is made large in order to improve the assemblability, the reaction gas flows out to the clearance and is not supplied to the electrode, so that the power generation performance is lowered.

On the other hand, when the seal member of the present invention is used, even if the electrode is displaced due to dimensional deviation, the sealability can be ensured because the clearance between the gasket and the electrode is sufficient. Further, when the stack is fastened at the time of assembly, the rib of the linear seal member that has been bent toward the anode side is curved so as to protrude toward the anode side with both end portions as fulcrums. At this time, a surface pressure necessary for sealing is generated in the sealing member due to a reaction force generated from the rigidity of the sealing member. Furthermore, the clearance between the electrode and the seal member is reduced by curving and projecting toward the electrode side.
Furthermore, since the sealing members are arranged in the stacking direction, no shear force or bending moment acts on the electrolyte membrane or the separator plate when the stack is fastened. Therefore, there is no stress on the seal member itself, the electrolyte membrane, the separator plate, etc., and there is no risk of the member being damaged.

  The battery A of Example 1 and the battery C of Comparative Example 2 were kept at 75 ° C., and the humidified and heated hydrogen gas was adjusted to a dew point of 70 ° C. on the anode side, and the dew point of 60 ° C. was set on the cathode side Humidified and warmed air was supplied. As a result, an open voltage of 50 V was obtained at the time of no load when neither battery supplies power to the outside. It was also confirmed that there were no problems such as gas cross leak and short circuit.

Furthermore, the fuel utilization rate is 80%, the current density is 0.3 A / cm ² , the anode side dew point is 70 ° C., the oxidant gas side dew point is 65 ° C., and the oxidant utilization rate is from 20% in 5% increments every 12 hours. Power generation was started under changing conditions. Then, the stability of power generation under these conditions was investigated. The evaluation results are shown in FIG. In the battery C of Comparative Example 2, the output voltage became unstable when the oxidant utilization rate was 40% or more, and the output voltage decreased when the oxidant utilization rate was 50%. On the other hand, in the battery A of Example 1, a stable output voltage was obtained until the oxidant utilization rate exceeded 65%.

  From this, in the size of the clearance between the electrode and the flat gasket in the battery C of Comparative Example 2, the reaction gas easily flows into the clearance, and the amount of the reaction gas necessary for maintaining the battery performance is increased. It was found that the electrode could not be supplied. On the other hand, when the seal member of Example 1 is used, the clearance between the electrode and the seal member is large at the time of assembly, but the clearance between the electrode and the seal member is reduced when the battery stack is fastened. It was found that the inflow of the reaction gas into the clearance can be reduced and the deterioration of the battery performance can be prevented.

Furthermore, since the battery A of Example 1 has a significantly smaller fastening force than the batteries B and C of Comparative Examples 1 and 2, the fastening member itself used for the fuel cell can be simplified, made into a resin, and the like. Can be reduced in size and cost.
Compared with the case where an O-ring type gasket is used, in Example 1, there is no need to provide an O-ring groove in the separator plate, so that the thickness of the separator plate can be reduced accordingly, and the fuel can be reduced. Needless to say, the battery can be made compact.

Example 2
The anode-side linear seal member 56 shown in FIGS. 9 and 10 was produced by injection molding into a predetermined mold using fluororubber. At this time, the rib-like seal member 56a in the linear seal member 56 had a thickness of 0.25 mm, a curvature with a radius of 2.5 mm in the direction perpendicular to the anode side separator plate, and an opening angle of 35 °. Further, the plate-like seal member 56b in the anode-side linear seal member 56 has a thickness of 0.15 mm and a width of 3 mm.
A unit cell was fabricated as follows using the same member as in Example 1 except that the linear seal member 56 obtained above was used instead of the linear seal member 30 of Example 1.

The procedure for assembling the cell is shown below.
A predetermined assembly jig with a guide pin placed thereon was placed, and a cathode side separator plate provided with a cathode-side planar shape sealing member was placed thereon. Next, MEA was installed along the guide pin. At that time, the MEA cathode was carefully assembled so as not to run over the peripheral edge portion of the electrode installation portion 47 in the planar seal member on the cathode side.
After installing the MEA, the anode-side linear seal member 56 was assembled. At this time, a clearance of 0.7 mm between the anode and the electrode seal portion 57 in the linear seal member 56 on the anode side was secured. Thereafter, the anode separator plate 10 was assembled. Since the anode-side separator plate 10 is opaque, the state where the separator plate and the gasket are in contact cannot be visually observed. Therefore, the anode-side separator plate 10 was assembled according to the guide pins.

In this way, 50 unit cells are stacked, stainless steel end plates are arranged on both ends of the obtained stack via current collector plates and insulating plates, and the stack is fastened with a fastening load of 600 kgf by a fastening rod. Thus, a fuel cell was produced. This fuel cell was designated as cell D. After the fastening, the rib-like seal member 56a is curved toward the anode side, so that there is almost no clearance between the anode and the electrode seal portion 57. At this time, as a result of confirming the surface pressure of the MEA and the separator plate with the pressure sensitive paper, the surface pressure applied to the MEA was 10 kgf / cm ² . As a result, the reaction force in the seal member was 100 kgf, and it was found that a laminated battery can be configured with a sufficiently low fastening force.

The battery D was checked for gas leakage by the same method as in Example 1. As a result, there was no gas leak on the air side, the fuel gas side, and the cooling water side, and it was confirmed that the battery D had no problem in fluid sealability.
After the leak check, the battery D of Example 2 was disassembled and the assembling conditions of the constituent members were examined. The anode in the MEA was assembled with a slight deviation from the center of the linear seal member on the anode side. However, in the battery of this example, the portion to be sealed is on the outside with a sufficient margin than the electrode. It was found that sealability could be ensured in the electrode displacement range.

When assembling the unit cell, the anode separator plate is assembled after installing the MEA on the assembly jig. At this time, it is preferable that the anode in the MEA is installed at the center of the linear seal member on the anode side.
When the linear seal member on the anode side of the present embodiment is used, even if the electrode is displaced due to a dimensional displacement, the clearance between the seal member and the electrode is sufficient, so that the sealing performance can be ensured. Further, since visual assembly is possible, it is possible to reduce a sealing failure due to the biting of the electrode.

  Further, as in the case of the first embodiment, a large clearance at the time of assembling is obtained, and when the stack is fastened, a rib-shaped seal is used with the seal portion between the electrolyte membrane and the separator plate as a fulcrum due to the effect of the shape of the seal member of the second embodiment. The member curves to the electrode side. This is because the center of gravity of the rib-like seal member is on the electrode side with respect to the seal portion. At this time, a surface pressure necessary for sealing is generated at the seal portion due to a reaction force generated by the rigidity of the seal member. Moreover, the clearance between the MEA and the seal member can be reduced by the rib-like seal member being curved and protruding toward the electrode side.

  Furthermore, since the seal members are arranged in the vertical direction (stacking direction), no shearing force or bending moment acts on the electrolyte membrane or the separator plate when the stack is fastened. Therefore, there is no stress on the electrolyte membrane, the seal member, the separator plate, and the like, and there is no risk of the member being damaged.

  The battery D of Example 2 was held at 75 ° C., hydrogen gas humidified and heated to a dew point of 70 ° C. on the anode side, and air humidified and heated to a dew point of 60 ° C. on the cathode side. Each was supplied. As a result, an open voltage of 50 V was obtained at no load when power was not supplied to the outside. It was also confirmed that there were no problems such as gas cross leak and short circuit.

  With respect to this battery D, power generation was started under the same conditions as in Example 1, and the stability of power generation was examined. The evaluation results are shown in FIG. In the battery D of Example 2, a stable output voltage was obtained until the oxidant utilization rate exceeded 65%. Thus, in the fuel cell of Example 2, as in Example 1, the clearance between the electrode and the seal member is large when assembled, but the effect of the shape of the seal member when the stack is fastened, It has been found that the clearance with the seal member is reduced, the inflow of the reaction gas into the clearance can be reduced, and the deterioration of the battery performance can be prevented.

  Furthermore, since the fastening force required for fastening the fuel cell can be significantly reduced, the stack fastening members can be simplified, made resin, and the like. That is, the fuel cell can be made compact and the cost can be reduced.

Example 3
A linear seal member 56 was produced in the same manner as in Example 2 except that the thickness of the rib-like seal member 56a in the linear seal member 56 on the anode side in Example 2 was reduced to 0.15 mm.
Further, the linear seal member 56 was coated with an adhesive. As the pressure-sensitive adhesive, a copolymer of styrene and ethylene butylene was used. After applying a toluene solution of a copolymer of styrene and ethylene butylene to the linear sealing member, the toluene solvent was removed in a drying oven at 50 ° C.

  The linear sealing member 56 was pressure-bonded to the separator plate 10 by placing the linear sealing member 56 on the anode separator plate 10 and hot pressing the Teflon sheet thereon. At this time, the temperature was 100 ° C., the press load was 2000 kgf, and the pressing time was 1 minute.

A unit cell was produced in the same manner as in Example 2 except that the anode-side separator plate 10 provided with the anode-side linear seal member 56 obtained above was used. By stacking fifty unit cells, end plates made of stainless steel are arranged on both ends of the obtained stack via current collector plates and insulating plates, and the stack is fastened with a fastening load of 550 kgf by a fastening rod. A fuel cell was fabricated. This fuel cell was designated as cell E. At this time, as a result of confirming the surface pressure of the MEA and the separator plate with the pressure sensitive paper, the surface pressure applied to the MEA was 10 kgf / cm ² . As a result, the reaction force in the seal member is 50 kgf, and it has been found that a fuel cell can be configured with a very low fastening force. The assembled state was as good as in Examples 1 and 2.

For the battery E, a leak check was performed in the same manner as in Example 1. As a result, it was confirmed that there were no gas leaks on the air side, the fuel gas side, and the cooling water side, and there was no problem in the fluid sealability as a fuel cell.
In assembling the laminated battery, the MEA was placed on an assembly jig, and then the anode separator plate was assembled. At this time, the MEA anode is preferably installed at the center of the linear seal member on the anode side.

  When the rib-shaped seal member 56a is used, even when the electrode is displaced due to a dimensional shift, the clearance between the linear seal member on the anode side and the electrode is sufficient, so that sealing performance can be ensured. In addition, since the fuel cell can be assembled visually, it is possible to reduce the sealing failure due to the biting of the electrode.

Example 4
A fuel cell was produced in the same manner as in Example 3 except that the adhesive layer of Example 3 was not used. This fuel cell was designated as cell F.
The battery F of Comparative Example 3 was checked for leaks by the same method as in Example 1. As a result, in some of the single cells, there is a tendency that a gas external leak or a cross leak from the oxidant gas side to the fuel gas side, or both, may occur slightly, resulting in poor sealing.

  From Example 3, it was confirmed that by using an adhesive layer, sealing performance can be ensured even when a linear sealing member having a relatively small sealing reaction force as in this example is used. Thus, the reaction force required for the seal can be reduced, so that the fastening force of the stack can be greatly reduced. Therefore, the stack fastening member can be greatly simplified and made into a resin. That is, the fuel cell can be made compact and the cost can be reduced.

  Further, since the seal reaction force is very small, stress applied to the electrolyte membrane and the seal member can be reduced, damage to the electrolyte membrane and the seal member can be prevented, and long-term sealing performance can be ensured. Furthermore, reaction gas cross-leakage can be prevented, and damage to the electrolyte membrane due to gas cross-leakage due to poor sealing can be prevented, thus improving durability.

  The battery E of Example 3 was held at 75 ° C., hydrogen gas humidified and heated to a dew point of 70 ° C. on the anode side, and air humidified and heated to a dew point of 60 ° C. on the cathode side. Each was supplied. As a result, an open voltage of 50 V was obtained at no load when power was not supplied to the outside. It was also confirmed that there were no problems such as gas cross leak and short circuit.

With respect to this battery E, power generation was started under the same conditions as in Example 1, and the stability of power generation was examined. The evaluation results are shown in FIG. In the battery E of Example 3, a stable output voltage was obtained until the oxidant utilization rate exceeded 65%. From this, in the fuel cell of Example 3, as in Example 2, the clearance between the electrode and the linear seal member is large when assembled, but due to the effect of the shape of the linear seal member when the stack is fastened. It has been found that the clearance between the electrode and the linear seal member can be reduced, the inflow of the reaction gas into the clearance can be reduced, and the battery performance can be prevented from being lowered.
In addition, when an adhesion layer does not have acid resistance, the same effect as a present Example is acquired by inserting protective sheets, such as PFA, between an electrolyte membrane and a sealing member.

Example 5
Using a predetermined mold, a linear seal member on the anode side similar to that in FIGS. 11 and 12 in the first embodiment was produced by the same method as in the first embodiment.
Fuel cells G and H were produced in the same manner as in Example 1 except that this linear seal member was used instead of the anode-side linear seal member 30 used in Example 1.
Further, using a predetermined mold, an anode-side linear seal member similar to that in FIG. 13 in the second embodiment was produced by the same method as in the second embodiment. A fuel cell I was produced in the same manner as in Example 2 except that the linear seal member shown in FIG. 13 was used instead of the anode-side linear seal member in Example 2.

  Then, power generation for the batteries G to I was started under the same conditions as in Example 1, and the stability of power generation was examined. The evaluation results are shown in FIG. In any case, it was confirmed that stable output characteristics were obtained as in Example 1 or 2.

  As described above, the polymer electrolyte fuel cell of the present invention has a highly reliable assembly property when assembling the fuel cell, and reduces the clearance between the seal member and the electrode when the fuel cell is fastened. It has excellent sealing properties and stable output characteristics, and can be applied to applications such as portable power supplies, portable device power supplies, electric vehicle power supplies, and home cogeneration systems.

It is a front view of the anode side separator plate of this invention. It is a rear view of the anode side separator plate of this invention. It is a front view of the cathode side separator plate of this invention. It is a rear view of the cathode side separator plate of this invention. It is a front view of the anode side sealing member of Embodiment 1 of this invention. FIG. 6 is a cross-sectional view taken along line X ₁ -X _{2 in} FIG. 5. It is a front view of the cathode side sealing member of Embodiment 1 of the present invention. It is a Y ₁ -Y ₂ line sectional view of FIG. It is a front view of the anode side sealing member of Embodiment 2 of this invention. FIG. 10 is a sectional view taken along line Z ₁ -Z ₂ of FIG. FIG. 6 is a cross-sectional view of another anode side sealing member in the first embodiment. 6 is a cross-sectional view of still another anode side seal member according to Embodiment 1. FIG. FIG. 6 is a cross-sectional view of another anode side seal member in the second embodiment. 6 is a graph showing output characteristics of the battery A of Example 1 and the battery C of Comparative Example 2. FIG. 6 is a graph showing output characteristics of a battery D of Example 2. FIG. 6 is a graph showing output characteristics of a battery E of Example 3. FIG. It is a figure which shows the output characteristic of the batteries GI of Example 4. FIG.

Explanation of symbols

4a, 4b Film 5a, 5b Adhesive layer 10 Anode separator plate 11, 21, 41 Fastening bolt hole 12, 22, 32, 42, 52 Fuel gas manifold hole 13, 23, 33, 43, 53 For oxidant gas Manifold hole 14, 24, 34, 44, 54 Manifold hole for cooling water 15, 25, 35, 45, 55 Manifold hole for spare 12a, 13a, 14a O-ring groove 12b, 23b Gas flow path 14b 24b For cooling water Flow path 20 Cathode-side separator plate 30, 56 Anode-shaped linear seal member 36, 66, 76 Anode-side base seal member 36a, 66a, 76a Rib 36b, 57a, 57b, 66b, 76b Tip portion 37, 57, Electrode Seal part 40 Planar seal member on the cathode side 46 Base seal on the cathode side Material 56a ribbed sealing member 56b shaped sealing member

Claims (8)

A polymer electrolyte membrane; a pair of electrodes disposed on both surfaces of the electrolyte membrane; a pair of conductive separator plates having a gas flow path sandwiching the electrodes and supplying a reactive gas to the electrodes; and the pair of separator plates A fuel cell comprising a pair of sealing means sandwiching the electrolyte membrane therebetween and maintaining airtightness between the electrode and the pair of separator plates,
The pair of sealing means is composed of a combination of a planar sealing member having a planar portion in contact with the electrolyte membrane in a planar shape and a linear sealing member having ribs in contact with the electrolyte membrane in a linear shape,
It said pair of sealing means is disposed along the periphery of the front Symbol pair of electrodes,
The fuel cell, wherein when the electrolyte membrane, the pair of electrodes, and the pair of separator plates are stacked and fastened, at least a part of the rib falls in the electrode direction.   2. The fuel cell according to claim 1, wherein when the electrolyte membrane, the pair of electrodes, and the pair of separator plates are stacked and fastened, the whole of the rib falls down toward the electrode. The cross section of the rib in the stacking direction has a curved shape so that the rib approaches the electrode as it goes toward the center in the stacking direction ,
2. The fuel cell according to claim 1, wherein when the electrolyte membrane, the pair of electrodes, and the pair of separator plates are stacked and fastened, the rib is bent and curved toward the electrode. The rib is inclined toward the electrode;
2. The fuel cell according to claim 1, wherein when the electrolyte membrane, the pair of electrodes, and the pair of separator plates are stacked and fastened, the rib falls down to the electrode side. The rib has a circular portion at the tip in contact with the electrolyte membrane in the cross section in the stacking direction,
The fuel cell according to any one of claims 1 to 4, wherein a diameter of the circular portion is substantially half or more of a thickness of the electrode. The fuel cell according to any one of claims 1 , 2, and 4 , wherein a cross section of the rib in the stacking direction is linear. The fuel cell according to any one of claims 1 to 6 , wherein the pair of sealing means includes an adhesive layer. The fuel cell according to claim 7, wherein the adhesive layer has acid resistance.

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