JP2004303723A - Polymer electrolyte fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell with low cost having high reliability by using a compact seal member excellent in airtightness. <P>SOLUTION: The polymer electrolyte fuel cell comprises an anode side seal member and a cathode side seal member at an anode side separator and a cathode side separator respectively, and an anode side gas sealing part and a cathode side gas sealing part which prevent leakage of gas from the gas passage to the outside of the cell in cooperation with the polymer electrolyte membrane. The gas seal member at one side has a rib having a top part contacting linearly with the sealing part, and the gas seal member at the other side seals the sealing part by contacting the same in planar form at the part where the both gas sealing members are corresponding to both sealing parts. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a polymer electrolyte fuel cell used for a portable power supply, a power supply for an electric vehicle, 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 oxidizing gas containing oxygen such as air. This fuel cell includes a polymer electrolyte membrane for selectively transporting hydrogen ions, and a pair of electrodes formed on both sides of the polymer electrolyte membrane, that is, an anode and a cathode. The electrode is mainly composed of a carbon powder carrying a platinum-based metal catalyst, a catalyst layer formed on both surfaces of a polymer electrolyte membrane, and formed on the outer surface of the catalyst layer, having air permeability and electronic conductivity. And a gas diffusion layer also having

  Next, in order to prevent the supplied fuel gas and the oxidizing gas from leaking out or to mix the two types of gas with each other, a gas seal material or a gasket is provided around the electrodes with a polymer electrolyte membrane interposed therebetween. Be placed. The gas seal material and the gasket are integrated with the electrode and the polymer electrolyte membrane in advance and are assembled in advance, and this is called an MEA (electrolyte membrane / electrode assembly).

Outside the MEA, a conductive separator plate for mechanically fixing the MEA and electrically connecting adjacent MEAs to each other in series is arranged. The separator plate has a gas flow path for supplying a 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 in which a groove is provided on the surface of the separator plate to form a gas flow path is generally used.
In order to supply the reaction gas to the groove, a pipe jig for branching the pipe for supplying the reaction gas into the number of the separator plates to be used and connecting the branch directly to the groove on the separator plate is required. . This jig is referred to as a manifold, and the type directly connected from the reaction gas supply pipe as described above is referred to as an external manifold. In addition, there is a type of this manifold called an internal manifold having a simpler structure. In the internal manifold, a through-hole is provided in a separator plate having a gas flow path formed therein, an inlet / outlet of the gas flow path is passed to this hole, and a reaction gas is directly supplied from this hole.

  Since the fuel cell generates heat during operation, it is necessary to cool the fuel cell with cooling water or the like in order to maintain the cell in a favorable temperature state. Therefore, a flow path for cooling water is usually provided for every 1 to 3 cells. Usually, a cooling water flow path is provided on the back surface of the separator plate to serve as a cooling unit in many cases. Generally, these MEAs and separator plates are alternately stacked, and after stacking 10 to 200 cells, the stacked body is sandwiched between end plates via a current collector plate and an insulating plate and fixed from both ends with fastening bolts. This is a typical stacked battery structure.

The gasket of such a polymer electrolyte fuel cell needs to have high dimensional accuracy, sufficient elasticity, and sufficient interference in order to perform gas sealing while making contact between the separator plate and the electrode. . For this reason, conventionally, a sheet-like gasket made of resin or rubber, an O-ring made of rubber, or the like has been used.
Recently, attempts have been made to reduce the load on the gasket in order to reduce the fastening load of the stack and reduce the weight, simplicity, and cost of structural members. A configuration using a gasket having a cross section such as a semi-circular shape or the like has been attempted (for example, JP-A-2002-141082). Further, in order to improve the assemblability, attempts have been made to configure a gasket on the separator plate side (for example, JP-A-2002-231264).

FIG. 13 is a longitudinal sectional view showing the vicinity of a gasket in a fuel cell using a conventional O-ring type gasket. O-rings 236 and 246 are provided in the O-ring grooves 236a and 246a provided on the anode-side separator plate 210 and the cathode-side separator plate 220, respectively. Then, the electrolyte membrane 231 is pressed against the cathode-side separator plate 220 with the O-ring 236, and the electrolyte membrane 231 is pressed against the anode-side separator plate 210 with the O-ring 246, thereby sealing between the membrane and the separator plate. 232a represents an anode, 232b represents a cathode, 212b represents a fuel gas flow path, and 223b represents an oxidizing gas flow path.
As described above, since the seal using the O-ring type gasket is performed at two places, there is a problem that a portion necessary for the seal becomes large.
In the case of an internal manifold type separator plate, since the gas seal portion extends from the manifold to the electrode portion, the electrolyte membrane needs to be large enough to cover the manifold, thereby increasing the cost. Furthermore, since the thickness of the electrolyte membrane is about 25 to 50 μm, the larger the membrane size, the more difficult it is to handle during assembly.

On the other hand, when a unit battery is configured to reduce the size of the electrolyte membrane to reduce cost, improve handling, and improve strength and cover it with a somewhat rigid protective film, a step corresponding to the thickness of the electrolyte membrane is required. , There is a problem that the sealing performance is reduced. Furthermore, when the above-described O-ring is used for the gasket, since the gasket itself has no rigidity, a time is required in a process of assembling the thin O-ring without twisting when assembling the battery stack, and there is a problem that the manufacturing cost is increased. .
In addition, since the separator plate is made of a conductive material, there is a possibility that the separator plates sandwiching the MEA may be short-circuited due to mixing of a conductive foreign substance in the assembly process. In addition, there is a possibility that a short circuit occurs between the separator plates due to warpage or distortion of the separator plates, or distortion generated when the laminated battery is assembled. Further, there is a possibility that separator plates sandwiching the MEA may be short-circuited due to foreign matter having conductivity entering between the laminated battery and the heat insulating material after assembly.

  Furthermore, in the case of sealing with an O-ring, when assembling a laminated battery, a process of stacking these components such as placing a separator below, placing an MEA thereon, and stacking a separator or a gasket and a separator thereon is performed. Be taken. At this time, the gasket or separator placed on the MEA is assembled by a guide of an assembly jig. However, each component has a dimensional error, and especially if the clearance between the gasket and the MEA is not large enough to absorb the dimensional error, the assemblability cannot be ensured. As a result, a clearance is created between the gasket and the electrode, through which the reaction gas passes, bypassing the gas flow path of the separator.

The clearance between the electrode and the gasket varies from cell to cell due to an error in assembling the MEA or gasket, and the pressure loss between cells varies. When a variation in pressure loss occurs between the cells, in the stacked battery, a reaction gas corresponding to the pressure loss of each cell flows to each cell, so that the flow rate of the reaction gas varies. As a result, the battery performance varies, 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 anode side where the reaction gas utilization was relatively large.
Also, if the clearance between the gasket and the electrode is to be reduced, the dimensional accuracy of the component must be improved, which leads to a decrease in yield and an increase in component cost. Furthermore, since the assemblability is difficult, the reliability at the time of assembling is low, a sealing failure occurs due to a part of the electrode getting stuck in the seal portion, or excessive tensile stress and shear stress act on the electrolyte membrane, This may cause damage to the electrolyte membrane and decrease in durability.

  In recent years, in order to improve battery performance, it is required to increase the degree of humidification of supplied gas. On the oxidant gas side, there is water produced by the reaction, and prompt and stable discharge of water from the electrode is desired. If the clearance between the gasket and the electrode is reduced or almost eliminated in order to prevent the above reaction gas from being bypassed by the conventional gasket, a large pressure is required to discharge water from the electrode, resulting in a decrease in system efficiency. There is also a problem. On the other hand, in order to reduce the weight, size, and cost of the stack fastening member, reduction of the sealing portion fastening force is also an issue, and an effective sealing structure with a simple configuration is required.

  An object of the present invention is to provide a highly reliable and low-cost fuel cell by using a compact sealing member having excellent airtightness in order to solve the above-mentioned problems.

The present invention
(1) a hydrogen ion conductive polymer electrolyte membrane, and a membrane electrode assembly (hereinafter, referred to as MEA) including an anode and a cathode sandwiching the polymer electrolyte membrane;
(2) an anode-side separator plate having a pair of fuel gas manifold holes and oxidizing gas manifold holes, and a gas flow passage connected to the fuel gas manifold holes and supplying and discharging fuel gas to and from the anode;
(3) A cathode-side separator plate having a pair of fuel gas manifold holes and a pair of oxidant gas manifold holes, and a gas flow path connected to the oxidant gas manifold holes to supply / discharge the oxidant gas to / from the cathode. ,
(4) an anode-side sealing member provided on the anode-side surface of the anode-side separator plate; and (5) a polymer electrolyte fuel comprising a cathode-side sealing member provided on the cathode-side surface of the cathode-side separator plate Battery.

In the polymer electrolyte fuel cell of the present invention, a cell constituted by sandwiching the MEA under pressure between an anode-side separator plate and a cathode-side separator plate comprises the anode-side sealing member, the cathode-side sealing member, and the polymer electrolyte membrane. Cooperate to prevent the gas from leaking from the fuel gas flow path to the outside, and the cathode gas seal to prevent the gas from leaking to the outside from the oxidant gas flow path. Part
In the corresponding portions of the gas seal portions, one of the gas seal members has a rib having a top portion linearly in contact with the seal portion, and the other has a planar contact with the seal portion.

The polymer electrolyte fuel cell according to the first preferred embodiment of the present invention,
The polymer electrolyte membrane has a pair of fuel gas manifold holes and a pair of oxidant gas manifold holes,
The anode-side seal member has a first anode-side seal portion surrounding the anode and the outer periphery of each manifold hole to form one closed loop, and a second anode-side seal portion separating the anode from each manifold hole. And
The cathode-side seal member has a first cathode-side seal portion surrounding the outer periphery of the cathode and each manifold hole to form one closed loop, and a second cathode-side seal portion separating the cathode from each manifold hole. And
In each of the seal portions, the two seal members are sandwiched between the separator plates and pressed against the polymer electrolyte membrane, and one of the seal members has a top portion in linear contact with the polymer electrolyte membrane at the pressed portion. It has a rib, and the other sealing member is in planar contact with the polymer electrolyte membrane.

The polymer electrolyte fuel cell according to the second preferred embodiment of the present invention,
The polymer electrolyte membrane has a pair of fuel gas manifold holes and a pair of oxidant gas manifold holes,
A first anode-side seal portion surrounding the outer periphery of the anode and each manifold hole to form a closed loop, and a second anode-side seal separating the anode from the oxidant gas manifold hole; Part
The cathode side sealing member surrounds the outer periphery of the cathode and each of the manifold holes to form a single closed loop, and a second cathode side sealing portion for isolating the cathode from the fuel gas manifold hole. Has,
In each of the seal portions, the two seal members are sandwiched between the separator plates and pressed against the polymer electrolyte membrane, and one of the seal members has a top portion in linear contact with the polymer electrolyte membrane at the pressed portion. It has a rib, and the other sealing member is in planar contact with the polymer electrolyte membrane.

The polymer electrolyte fuel cell according to the third preferred embodiment of the present invention,
The hydrogen ion conductive polymer electrolyte membrane has a size sufficient to cover the anode and the cathode, but has a size not in contact with each of the manifold holes,
A first anode-side sealing portion surrounding the outer periphery of the anode and the fuel gas manifold hole to form one closed loop, and an outer periphery of the polymer electrolyte membrane together with the first anode-side sealing portion; And a second anode-side seal portion surrounding the anode, wherein the first anode-side seal portion is in contact with the polymer electrolyte membrane at a portion surrounding the anode,
A first cathode-side seal portion surrounding the outer periphery of the cathode and the oxidant gas manifold hole to form one closed loop; and the first cathode-side seal portion together with the polymer electrolyte membrane. A second cathode-side sealing portion surrounding the outer periphery, wherein the first cathode-side sealing portion is in contact with the polymer electrolyte membrane at a portion surrounding the cathode;
The respective seal portions are located at positions corresponding to each other except for inevitable portions, and the two seal members are sandwiched between the two separator plates in the seal portion or directly through a polymer electrolyte membrane. One of the seal members has a rib having a top portion linearly in contact with the polymer electrolyte membrane or the other seal member at the pressed portion, and the other seal member is in planar contact with the portion.
In the third embodiment, the one seal member is such that the height of a rib in a portion of the first seal portion that is not in contact with the polymer electrolyte membrane and a height of a rib in the second seal portion are in the first seal portion. It is preferable that the height be higher than the height of the portion in contact with the polymer electrolyte membrane.

The polymer electrolyte fuel cell according to the fourth preferred embodiment of the present invention,
In a portion surrounding the anode or the cathode, the rib of the one sealing member is of a wedge type with a thin inside and a thick outside.
In the fourth embodiment, the one sealing member is a cathode-side sealing member, and the cathode-side sealing member is
(A) a band-shaped first piece surrounding a flow path of the oxidizing gas and a pair of manifold holes connected thereto to form a closed loop;
(B) a pair of band-shaped second parts surrounding the pair of fuel gas manifold holes to form a closed loop, and (c) a band-shaped second part connecting the first part and the second part. (D) the first part is a rust type having a thinner inside and a thicker outer part, and the second part is also a rust having a thicker inside and a thinner outside. It is preferably a mold.

As a method of installing the seal member on the anode-side separator plate and / or the cathode-side separator plate, there are the following modes.
The main surface of the separator plate is covered with the sealing member.
A seal member is formed on the separator plate.
A seal member is fitted to the separator plate.
A seal member is adhered to the separator plate.

  ADVANTAGE OF THE INVENTION According to this invention, since the space of a sealing member is made small and excellent airtightness is exhibited, the fastening load of a battery stack can be reduced. Therefore, a highly reliable and low-cost fuel cell can be provided.

In one aspect of the present invention, an anode-side gas seal portion that prevents a gas from leaking from a gas flow path of a cell to the outside in cooperation of an anode-side seal member, a cathode-side seal member, and a polymer electrolyte membrane And a gas seal member on the cathode side, and both gas seal members have a rib having a top portion linearly contacting the seal portion in a corresponding portion of the gas seal portions, and the other has a seal portion in the seal portion. It is characterized in that sealing is performed by being in contact with the surface.
The point of the present invention is that by using the sealing member having the above-described configuration, it is possible to secure stable airtightness, reduce the space of the sealing member, and reduce the fastening load of the battery stack. It is in.

  In another aspect of the present invention, the cross-sectional shape of the seal member that constitutes the seal portion interposed between the polymer electrolyte membrane and each separator is such that the anode-side seal member has a planar shape, and the cathode-side seal member has a cathode shape. Is thinner on the cathode side and thicker in the opposite direction, and has a wedge shape. According to this configuration, not only the space required for the seal portion is reduced, but also the fastening load of the stack is reduced, and furthermore, the required minimum constant between the electrode and the seal member for discharging water and securing assemblability is required. Clearance can be secured. In addition, it is possible to easily assemble the cell and to ensure the water discharge performance at low pressure loss.

In still another aspect, the present invention provides a hydraulic pressure diameter (d) of a clearance generated between a sealing member and an electrode, wherein the configuration of the sealing member is determined by the configuration of a gas flow path of a separator and a limitation requirement due to assemblability. Is found to be definable by
That is, the one-side clearance cl generated between the cathode surrounding portion of the cathode-side sealing member and the cathode and the hydraulic diameter d of the clearance are designed to satisfy the following expression (1). More preferably, the expression (2) is satisfied.

d <(D × l × P) /0.54L (1)
However,
l: Length of one-side clearance part d: Hydraulic diameter of one-side clearance part L: Length of gas flow path per pass of cathode-side separator D: Hydraulic diameter of gas flow path per pass of cathode-side separator P: Number of gas flow paths per cathode-side separator Hydraulic diameter d = cross-sectional area of clearance section / perimeter of cross-sectional area of clearance section × 4

    0.25mm <cl (2)

Thus, a seal member is provided which reduces the influence of variations in the dimensions of each part and the effects of assembly errors, and enables a cell configuration with less variation in pressure loss.
From still another viewpoint, the present inventors have found that the region where the operation can be performed practically can be arranged by the ratio of the pressure loss Pc of the clearance portion to the pressure loss Pf of the gas passage portion. That is, it is effective to set 0.9 <Pc / Pf.

  As the rubber layer used for the seal member, polyisoprene, butyl rubber, ethylene propylene rubber, and the like can be used in addition to fluoro rubber. As the pressure-sensitive adhesive, polyisobutylene, ethylene propylene rubber, butyl rubber, a composite thereof, or the like can be used.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The drawings used here illustrate the structure, and the relative positions and sizes of the components are not always accurate.

Embodiment 1
FIG. 1 shows a front view of the anode-side separator plate, and FIG. 2 shows a rear view thereof.
The anode-side separator plate 10 has a pair of fuel gas manifold holes 12, an oxidizing gas manifold hole 13, a cooling water manifold hole 14, a spare manifold hole 15, and four fastening bolt holes 11. .
On the surface of the anode-side separator plate 10 facing the anode, there is provided a gas flow passage 12b which is connected to the pair of fuel gas manifold holes 12 and supplies / discharges the fuel gas to / from the anode. The gas flow path 12b is constituted by one groove. Reference numeral 12c denotes a gas flow path at a portion connected to the fuel gas manifold hole 12.

  The separator plate 10 is provided with a cooling water flow path 14b connecting the pair of cooling water manifold holes 14 on the back surface thereof. The flow path 14b is formed by two parallel grooves. O-ring grooves 12a, 13a, and 15a for installing O-rings to surround the pair of fuel gas manifold holes 12, the oxidizing gas manifold holes 13, and the spare manifold holes 15 are provided. ing. Further, an O-ring groove 14a surrounding the cooling water manifold hole 14 and the cooling water flow path 14b is provided.

FIG. 3 shows a front view of the cathode-side separator plate, and FIG. 4 shows a rear view thereof.
The cathode-side separator plate 20 has a pair of fuel gas manifold holes 22, an oxidizing gas manifold hole 23, a cooling water manifold hole 24, a spare manifold hole 25, and four fastening bolt holes 21. .
On the surface of the cathode-side separator plate 20 facing the cathode, there is provided a gas flow passage 23b which is connected to the pair of oxidant gas manifold holes 23 and supplies / discharges the oxidant gas to / from the cathode. The gas flow path 23b is constituted by two grooves. Reference numeral 23c denotes a gas flow path in a portion connected to the oxidizing gas manifold hole 23.
The back surface of the separator plate 20 is provided with a flow path 24b for cooling water that connects the pair of cooling water manifold holes 24. The channel 24b is formed by two parallel grooves.

FIG. 5 is a front view of the anode-side sealing composite member, and FIG. 6 is an enlarged sectional view of a part thereof. FIG. 7 is a front view of the cathode-side sealing composite member, and FIG. 8 is an enlarged sectional view of a part thereof.
The anode-side sealing composite member 30 to be bonded to the anode-side separator plate 10 includes a polyimide film 4a, an anode-side sealing member 36 having a rib 36a on one surface thereof, and an anode-side separator formed on the other surface. It is composed of an adhesive layer 5a that adheres to the plate 10.

For the adhesive layer 5a, polyisobutylene, ethylene propylene rubber, butyl rubber, or the like may be used alone or in combination of two or more as an adhesive.
The film 4a and the adhesive layer 5a are provided with fuel gas manifold holes 32, oxidant gas manifold holes 33, cooling water manifold holes 34, and spare manifold holes 35 corresponding to the respective manifold holes in the anode-side separator plate 10. And a portion corresponding to the anode is cut out.

The anode-side seal member 36 includes an electrode seal portion 37 surrounding the anode, manifold hole seal portions 32a and 33a respectively surrounding the fuel gas manifold hole 32 and the oxidant gas manifold hole 33, and the manifold hole seal portions 32a and 33a. It has seal portions 38a, 38b and 38c, 38d connecting both ends of the electrode 33a to the electrode seal portion 37. The seal portions 38a and 38b surround both sides of the communication gas flow channel 12c in the anode side separator plate 10, and the seal portions 38c and 38d correspond to positions surrounding both sides of the communication gas flow channel 23c in the cathode side separator plate 20. are doing. The anode-side seal member 36 further has manifold hole seal portions 34a and 35a surrounding the manifold holes 34 and 35, respectively.
The rib 36a has a triangular cross-sectional shape, the bottom of which is included in the main surface of the anode-side sealing member 36, and the top 36b, which corresponds to the vertex facing the bottom, has a membrane formed on a cathode-side sealing member 46 described later. Contact.

On the other hand, the cathode-side sealing composite member 40 adhered to the cathode-side separator plate 20 has a film 4b made of polyimide, a flat-plate-shaped cathode-side sealing member 46 formed on one surface thereof, and a film 4b formed on the other surface. And a pressure-sensitive adhesive layer 5b adhered to the separator plate.
For the adhesive layer 5b, polyisobutylene, ethylene propylene rubber, butyl rubber, or the like may be used alone or in combination of two or more as an adhesive.
The film 4b and the adhesive layer 5b are provided with a fuel gas manifold hole 42, an oxidizing 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, And a portion corresponding to the cathode is cut out.
The cathode-side sealing member 46 is flat and has the same shape as the film 4b and the adhesive layer 5b.

The anode-side sealing member 36 is fixed to the anode-side separator plate 10 by bonding the surface of the adhesive layer 5a side of the anode-side sealing composite member 30 to the surface of the anode-side separator plate 10 facing the anode. You.
On the other hand, the cathode-side sealing member 46 is fixed to the cathode-side separator plate 20 by adhering the surface on the adhesive layer 5b side of the cathode-side sealing composite member 40 to the surface of the cathode-side separator plate 20 facing the cathode. You.
When constructing the fuel cell, as shown in FIG. 11, an anode-side separator plate 10 provided with these anode-side sealing composite members 30 and a cathode-side separator plate provided with the cathode-side sealing composite members 40 are provided. 20 and the MEA. The MEA includes a hydrogen ion conductive polymer electrolyte membrane 1 and an anode 2a and a cathode 2b sandwiching the electrolyte membrane 1. In FIG. 11, reference numeral 3 denotes an O-ring provided in the grooves 12a to 15a.
At this time, as shown in FIG. 12, the top 36 b of the anode-side seal member 36 is configured to contact the cathode-side seal member 46 via the electrolyte membrane 1.
By using such an anode-side seal member and a cathode-side seal member, it is possible to reduce the space for the seal member and reduce the fastening load of the battery stack while ensuring stable airtightness.

The fuel cell described above includes an anode-side sealing member joined to the anode-side separator plate and a cathode-side sealing member joined to the cathode-side separator plate. These pair of sealing members,
(A) a pair of electrode seal portions sandwiching the polymer electrolyte membrane at positions surrounding the anode and the cathode,
(B) a pair of manifold hole seals sandwiching the polymer electrolyte membrane at positions surrounding the fuel gas manifold hole and the oxidizing gas manifold hole; and (c) a communication gas for connecting each manifold hole to the gas flow path. A pair of communicating gas flow path seals sandwiching the polymer electrolyte membrane at positions surrounding both sides of the flow path.
The sealing member has a rib having an apex linearly in contact with the polymer electrolyte membrane at each seal portion, and the other comes into contact with the polymer electrolyte membrane in a planar manner. Maintain airtightness between the separator plates.

In the anode-side sealing composite member 30 having the above-described configuration, the anode and the fuel gas manifold hole 32 are separated by the manifold hole sealing portion 32a and the electrode sealing portion 37 surrounding the anode. Similarly, the anode and the oxidant gas manifold hole 33 are separated by a manifold hole seal portion 33a and an electrode seal portion 37. The anode and the manifold holes 32, 33 may be isolated only by the manifold hole seal portions 32a, 33a as shown in FIG. Also, as shown in FIG. 10, the electrodes may be isolated only by the electrode seal portion 37 surrounding the anode.
Further, the composite member 40 for cathode side sealing having the above-described configuration had a shape covering the entire main surface of the separator plate including the respective seal portions of the electrode seal portion, the manifold hole seal portion, and the communication gas flow passage seal portion. However, the cathode-side sealing composite member 40 may be configured with only a portion facing the anode-side sealing member 30.

Embodiment 2
FIG. 14 is a front view of the anode-side separator plate, and FIG. 15 is a front view of the cathode-side separator plate.
The anode-side separator plate 50 has a pair of fuel gas manifold holes 52, an oxidizing gas manifold hole 53, a cooling water manifold hole 54, a spare manifold hole 55, and four fastening bolt holes 51. .
The cathode-side separator plate 60 has a pair of fuel gas manifold holes 62, an oxidizing gas manifold hole 63, a cooling water manifold hole 64, a spare manifold hole 65, and four fastening bolt holes 61. .
The anode-side separator plate 50 and the cathode-side separator plate 60 are provided at predetermined positions with seal member grooves 50a and 60a for disposing an anode-side seal member 56 and a cathode-side seal member 66, which will be described later. I have.

FIG. 16 is a front view of the anode-side separator plate 50 in which the anode-side sealing member 56 is provided in the groove 50a, and FIG. 17 is an enlarged sectional view of a part thereof. FIG. 19 is a front view of the cathode-side separator plate 60 in which the cathode-side sealing member 66 is provided in the groove 60a, and FIG. 20 is an enlarged sectional view of a part thereof.
An anode-side sealing member 56 having a predetermined rib 56a is provided along the sealing member groove 50a of the anode-side separator plate 50.
The anode-side seal member 56 has a first anode-side seal portion surrounding the gas flow path 52b and the outer periphery of the pair of fuel gas manifold holes 52 to form one closed loop. The anode-side seal member 56 further includes manifold hole seal portions 53a, 54a, and 55a that independently surround the oxidant gas manifold hole 53, the cooling water manifold hole 54, and the spare manifold hole 55, respectively, and a cathode side described below. The separator plate 60 has seal portions 58c and 58d surrounding both sides of the communication gas flow channel 63c.

The first anode side seal portion includes an electrode seal portion 57 surrounding most of the gas flow passage 52b, a manifold hole seal portion 52a surrounding the outer half of the fuel gas manifold hole 52, and both sides of the communication gas flow passage 52c. And seal portions 58a and 58b surrounding the The communication gas flow path 52c connects the manifold hole 52 and the gas flow path 52b. This first anode-side seal portion corresponds to the hatched portion in FIG.
Further, the anode-side seal member 56 has seal portions 59a, 59b, 59c, and 59d. The seal portion 59a connects the fuel gas manifold hole seal portion 52a and the oxidant gas manifold hole seal portion 53a. The seal portion 59b connects the fuel gas manifold hole seal portion 52a and the cooling water manifold hole seal portion 54a. The seal portion 59c connects the oxidant gas manifold hole seal portion 53a and the spare manifold hole seal portion 55a. The sealing portion 59d connects the cooling water manifold hole sealing portion 54a and the spare manifold hole sealing portion 55a.

  The second anode-side seal portion includes the respective manifold hole seal portions 53a to 55a and the respective seal portions 59a, 59b, 59c, and 59d connecting the respective manifold hole seal portions, and among these, the first anode-side seal portion And a portion forming a closed loop inside the manifold holes 53 to 55 together with the fuel gas manifold hole sealing portion 52a.

On the other hand, a cathode-side sealing member 66 having a flat surface facing the anode-side separator plate is provided along the sealing member groove 60 a of the cathode-side separator plate 60.
The cathode-side seal member 66 includes a first cathode-side seal portion surrounding the gas flow path 63b and the outer circumference of the pair of oxidant gas manifold holes 63 to form one closed loop, the fuel gas manifold hole 62, and cooling water. Seal holes 62a, 64a, and 65a independently surrounding the manifold holes 64 and the spare manifold holes 65, and seal portions 68a, 68b surrounding both sides of the communication gas flow channel 52c in the anode-side separator plate 50. And

The first cathode-side seal portion includes an electrode seal portion 67 surrounding most of the gas passage 63b, a manifold hole seal portion 63a surrounding the outer half of the oxidant gas manifold hole 63, and the manifold hole 63 and the gas passage. It is composed of seal portions 68c and 68d surrounding both sides of the communication gas channel 63c communicating with the gas passage 63b. This first cathode-side seal portion corresponds to the hatched portion in FIG.
Further, the cathode-side seal member 66 has seal portions 69a, 69b, 69c, and a seal portion 69d. The seal portion 69a connects the fuel gas manifold hole seal portion 62a and the oxidant gas manifold hole seal portion 63a. The seal portion 69b connects the fuel gas manifold hole seal portion 62a and the cooling water manifold hole seal portion 64a. The seal portion 69c connects the oxidant gas manifold hole seal portion 63a and the spare manifold hole seal portion 65a. The sealing portion 69d connects the cooling water manifold hole sealing portion 64a and the spare manifold hole sealing portion 65a.

The second cathode-side seal portion includes the respective manifold hole seal portions 62a, 64a, and 65a, and the respective seal portions 69a, 69b, 69c, and 69d that connect the respective manifold hole seal portions. Together with the oxidizing gas manifold hole seal portion 63a in the side seal portion, it corresponds to a portion forming a closed loop inside the manifold holes 62, 64, 65.
When configuring the fuel cell, when the anode-side separator plate 50 and the cathode-side separator plate 60 are arranged on both sides of the MEA, the top 56b of the rib 56a in the anode-side sealing member 56 is interposed with an electrolyte membrane. To contact the cathode side sealing member 66.
By using such a sealing member, it is possible to reduce the space for the sealing member and reduce the fastening load of the battery stack while securing stable airtightness.

  Further, in the present embodiment, it is possible to use a polymer electrolyte membrane having a size slightly smaller than that of the separator plate. In FIG. 16, the outline of the polymer electrolyte membrane is indicated by a dotted line. When a polymer electrolyte membrane having such a size is used, a gap is formed in a contact portion between the seal portions 58a and 58b and the polymer electrolyte membrane, and fuel gas leaks outside the first anode-side seal portion. The second anode-side seal portion prevents the leaked gas from leaking out of the cell. The second anode-side seal portion, which is essential for preventing the gas from leaking to the outside, is shown in FIG. 22 outside the first anode-side seal portion.

In addition, a gap is formed at a contact portion between the seal portions 68c and 68d and the polymer electrolyte membrane, and the oxidant gas leaks outside the first cathode-side seal portion. The second cathode-side seal portion prevents the leaked gas from leaking out of the cell. The second cathode-side sealing portion, which is essential for preventing the gas from leaking to the outside, is shown in FIG. 23 outside the first cathode-side sealing portion.
Further, since the second anode-side seal portion and the second cathode-side seal portion surround the inside of the manifold hole other than the manifold hole connected to the gas flow path, the gas leaks inside the fuel cell. I can't.

  As described above, even when a polymer electrolyte membrane having a small size as shown by a dotted line in FIG. 16 is used, the anode separator plate and the cathode seal member provided with the anode seal member of the present embodiment are provided. By using the cathode-side separator plate, stable airtightness can be secured. Further, since the size of the polymer electrolyte membrane can be reduced, the fastening load of the stack can be further reduced.

In the above description, the ribs 56a forming the respective seal portions of the anode-side seal member 56 have been described as having the same height. However, the height of the ribs not in contact with the polymer electrolyte membrane can be further enhanced by increasing the height of the ribs in contact with the polymer electrolyte membrane by the thickness of the polymer electrolyte membrane.
FIG. 18 is an enlarged cross-sectional view of the separator 50 with the anode-side sealing member in such an embodiment, taken along a line corresponding to line 18-18 in FIG. Of the ribs 56a of the seal member 56, a portion in contact with the polymer electrolyte membrane 1 having a size indicated by a dotted line in FIG. 16 is represented by 56a-1, and a portion not in contact with the polymer electrolyte membrane is represented by 56a-2. The rib 56a-2 is higher than the rib 56a-1 by the thickness of the polymer electrolyte membrane. The rib 56a-1 and the rib 56a-2 are connected by a portion 56a-3 whose height is gradually increased.
Instead of increasing the height of the rib 56 itself, the height (thickness) of the portion serving as the base of the rib may be increased to increase the height of the rib.

  Instead of changing the height of the ribs of the anode-side sealing member, the height (thickness) of the cathode-side sealing member may be changed. FIG. 21 is an enlarged cross-sectional view of the cathode-side separator provided with such a seal member, taken along a line corresponding to line 21-21 in FIG. In the sealing portion 68d of the sealing member 66, a portion in contact with the polymer electrolyte membrane 1 having a size indicated by a dotted line in FIG. 16 is represented by 68d-1, and a portion not in contact with the polymer electrolyte membrane is represented by 68d-2. The portion 68d-2 is higher than 68d-1 by the thickness of the polymer electrolyte membrane. The portions 68d-1 and 68d-2 are connected by a portion 68d-3 whose height is gradually increased. The other seal portions that are not in contact with the polymer electrolyte membrane are higher than those in contact with the polymer electrolyte membrane.

In addition, the above-mentioned two seal members have non-corresponding parts (parts separating the oxidant gas manifold and the anode in the oxidant gas manifold hole seal part and the electrode seal part of the anode side seal member in FIG. 16, and In FIG. 19, there is a portion for separating the fuel gas manifold hole from the cathode in the fuel gas manifold hole seal portion and the electrode seal portion of the cathode side seal member. However, when the fuel cell stack is constructed, the elastic seal member is pressed by the two separator plates at an appropriate pressure. Therefore, even if the seal members do not correspond to each other, one of the seal members directly contacts the separator plate. Can be sealed by contact with
Alternatively, a member such as a cover plate may be used for the above-mentioned non-corresponding portions, and the portions may be sealed in correspondence with the sealing members. For example, in the case of FIG. 16, a cover plate that covers above the communication gas flow channel 52c can be provided at a position corresponding to the cathode-side seal member between the pair of seal portions 58a and 58b. In the case of FIG. 19, a cover plate that covers the upper part of the communication gas flow channel 63c can be provided at a position corresponding to the anode-side seal member between the pair of seal portions 68c and 68d.

Examples of a method of installing the seal member in the seal member groove include a method of integrally forming the seal member in the groove portion of the separator plate and a method of fitting a preformed seal member in the groove.
26 and 27 show an anode-side separator plate 50 provided with another anode-side sealing member. The seal member 76 is fitted into the groove 50a of the anode-side separator plate 50 as in FIG. 14, and is integrally connected to the separator. The difference between the seal member 56 and the seal member 56 is that of the separator plate 50 except for a portion surrounded by a first anode-side seal portion, manifold holes 53, 54 and 55, and a fastening bolt hole 51 described below. It covers the main surface. The seal member 76 has a rib 76a at the same position as the rib 56a of the seal member 56 shown in FIG. In FIG. 26, the portion of the rib 76a corresponding to the top 76b is represented by a single line. With this seal member 76, it is possible to prevent a pair of separator plates sandwiching the MEA from contacting each other to prevent a short circuit.

The anode-side seal member 76 includes a first anode-side seal portion surrounding the gas flow path 52b and the outer periphery of the pair of fuel gas manifold holes 52 to form one closed loop, the oxidant gas manifold hole 53, and cooling water. Hole seal portions 73a, 74a and 75a independently surrounding the manifold hole 54 and the spare manifold hole 55, and seal portions 78c and 78d surrounding both sides of the communication gas channel 63c in the cathode-side separator plate 60. Have. The anode-side seal member 76 further includes a seal portion 79a connecting the manifold hole seal portions 72a and 73a, a seal portion 79b connecting the manifold hole seal portions 72a and 74a, a seal portion 79c connecting the manifold hole seal portions 73a and 75a, and a manifold hole. There is a seal portion 79d connecting the seal portions 74a and 75a.
The first anode-side seal portion includes an electrode seal portion 77 surrounding most of the gas passage 52b, a manifold hole seal portion 72a surrounding the outer half of the fuel gas manifold hole 52, and the manifold hole 52 and the gas passage 52b. And seal portions 78a and 78b surrounding both sides of the communication gas flow path 52c for communicating These seal portions are located at positions corresponding to the seal portions of the seal member in FIG.
Further, as shown in FIG. 28, an anode-side seal member 86 provided with a rib 86a at the same position as in FIG. May be. 86b represents the top of the rib 86a. This can prevent a short circuit between the pair of separator plates sandwiching the MEA and a short circuit after assembling the stacked battery.

(I) Production of Separator Plate The anode-side separator plate 10 shown in FIGS. 1 and 2 of Embodiment 1 and the 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 flow path for gas and cooling water were 3 mm pitch and 2 mm in groove width.

(Ii) Production of Seal Member Seal composite members 30 and 40 each having the same adhesive layer as in Embodiment 1 shown in FIGS. 5 to 8 were produced.
A 100 μm-thick polyimide film 4a was placed in a mold. After closing the mold, a predetermined sealing member 36 was formed on the polyimide film 4a by injection-molding fluorine rubber under the conditions of a temperature of 200 ° C. and an injection pressure of 150 kgf / cm ² . Similarly, a predetermined sealing member 46 was formed on the polyimide film 4b having a thickness of 100 μm. Secondary crosslinking was performed at 200 ° C. for 10 hours. Thereafter, adhesive layers 5a and 5b of butyl rubber having a thickness of 25 μm were transferred and bonded onto the polyimide films 4a and 4b, respectively, and the surfaces of the adhesive layers 5a and 5b were covered with a release film made of polypropylene.

At this time, the thickness of the anode-side sealing member 36 was 100 μm, the width thereof was 3 mm, and the height of the rib 36 a from the main surface of the sealing member 36 was 300 μm. On the other hand, the thickness of the cathode-side sealing member 46 was 125 μm. Also, the fuel gas, the oxidizing gas, the cooling water and the spare manifold holes 32 to 35 and 42 to 45 in the anode-side and cathode-side sealing composite members 30 and 40, the fastening bolt holes 31 and 41, and the electrodes facing the electrodes. The part to be cut was pulled out with a die.
The sealing composite members 30 and 40 each having the adhesive layer obtained above were placed on the separator plates 10 and 20, respectively, and pressed by hot pressing. The conditions for the hot pressing were as follows: the temperature was 100 ° C., the pressing load was 2000 kgf, and the pressing time was 1 minute.

(Iii) Preparation of MEA Platinum particles having an average particle size of about 30 ° were supported on an acetylene black-based carbon powder at a weight ratio of 4: 1 to obtain a catalyst powder for an electrode. An electrode paste was obtained by mixing the catalyst powder dispersed in isopropanol and the perfluorocarbon sulfonic acid powder dispersed in ethyl alcohol. Using the electrode paste as a raw material, a catalyst layer was formed on one surface of a carbon nonwoven fabric having a thickness of 250 μm by a screen printing method to obtain an electrode. Amount of platinum contained in the catalyst layer is 0.5 mg / cm ^2, the amount of perfluorocarbon sulfonic acid was 1.2 mg / cm ^2.

These electrodes had the same configuration for both the positive electrode and the negative electrode. With the printed catalyst layer on the inside, a hydrogen ion conductive polymer electrolyte membrane was sandwiched between a pair of electrodes having an area of 100 cm ² , and hot pressing was performed to produce an electrolyte membrane / electrode assembly (MEA). 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 polymer electrolyte membrane is punched with holes corresponding to a pair of fuel gas manifold holes, cooling water manifold holes, and oxidant gas manifold holes described later. Formed by mold.

(Iv) Production of Stacked Battery FIG. 11 shows a vertical sectional view of a main part of the stacked battery.
The anode-side separator plate 10 provided with the anode-side sealing composite member 30 and the cathode-side separator plate 20 provided with the cathode-side sealing composite member 40 obtained above are used to form the hydrogen ion conductive polymer electrolyte membrane 1 and the electrolyte. A unit battery was configured with an MEA including a pair of anodes 2a and cathodes 2b sandwiching the membrane 1 therebetween. At this time, the O-ring 3 was installed in the O-ring grooves 12a to 15a of the anode-side separator plate 10. Then, when stacking the unit cells, the surface of the separator plate 10 having the cooling water channel 14b and the surface of the adjacent unit cell separator plate 20 having the cooling water channel 24b face each other. Thereby, a cooling unit was provided.

In this way, 50 unit cells are stacked, and a stainless steel end plate is arranged at both ends of the stack via a current collector and an insulating plate, and the stack is fastened with a fastening load of 700 kgf by a fastening rod. Thus, a laminated battery was produced. This laminated battery was designated as Battery A.
At this time, the surface pressure of the MEA and the separator was confirmed using pressure-sensitive paper. As a result, the surface pressure applied to the MEA was 10 kgf / cm ² . As a result, it was found that the reaction force of the seal member was 200 kgf.

Battery A was checked for gas leaks. The outlet-side manifold hole was closed, and He gas was allowed to flow from the inlet-side manifold hole at a pressure of 0.5 kgf / cm ² , and the flow rate of the flowing gas at that time was examined. There was no gas leak on the air side, the fuel gas side, and the cooling water side, and it was confirmed that Battery A had no problem with the fluid sealability.

<< Comparative Example 1 >>
A pair of separator plates 210 and 220 having conventional O-ring grooves 236a and 246a as shown in FIG. 13 were produced by machining using an isotropic graphite plate. At this time, the width of the O-ring grooves 236a and 246a was 1.5 mm and the depth was 0.8 mm. Then, O-rings 236 and 246 were produced by compression molding using a predetermined mold. In addition, fluorine rubber having a rubber hardness of 60 was used for the O-ring.
The laminated battery was manufactured in the same manner as in Example 1 except that the O-rings 236 and 246 and the separator plates 210 and 220 were used instead of the separator plates 10 and 20 and the sealing composite members 30 and 40 of Example 1. Was prepared. This laminated battery was designated as Battery B. Note that the other stack components had the same configuration as that of the first embodiment except that the size was changed according to the O-ring shape.

Battery B was checked for gas leakage in the same manner as in Example 1. As in Example 1, there was no gas leakage on the air side, the fuel gas side, and the cooling water side, and it was confirmed that there was no problem with the fluid sealability.
The battery A of Example 1 and the battery B of Comparative Example 1 were maintained at 85 ° C., and hydrogen gas humidified and heated to have a dew point of 83 ° C. on the anode side and 78 ° C. on the cathode side. Humidified and heated air was supplied. As a result, an open-circuit voltage of 50 V was obtained at the time of no load in which neither battery supplied power to the outside.
Further, the output characteristics of the batteries A and B were examined under the conditions of a fuel utilization of 80%, an oxygen utilization of 40%, and a current density of 0.5 A / cm ² . FIG. 29 shows the evaluation results. It was confirmed that the battery A of Example 1 of the present invention had the same performance as the battery B of the comparative example.

  The anode-side separator plate 50 and the cathode-side separator plate 60 of FIGS. 14 and 15 in Embodiment 2 were manufactured by machining using an isotropic graphite plate. At this time, the width of the sealing member grooves 50a and 60a provided in the anode-side separator plate 50 and the cathode-side separator plate 60 was 4 mm, and the depth was 1 mm. The thickness of the separator plates 50 and 60 was 3 mm, and the grooves of the flow passages formed on both sides were 3 mm pitch and 2 mm wide.

Next, a predetermined sealing member is formed on the separator plates 50 and 60, and the anode-side separator plate 50 provided with the sealing member 56 shown in FIGS. 16 and 17 in the second embodiment and shown in FIGS. 19 and 20. The cathode-side separator plates 60 each having the sealing member 66 were produced.
The molding of the seal member on the separator plate was performed by placing the separator plate in a mold, closing the mold, and injection-molding a fluoro rubber at a temperature of 200 ° C. and an injection pressure of 150 kgf / cm ² . At this time, the secondary crosslinking was performed at 200 ° C. for 10 hours.
The thickness of the anode-side sealing member 56 was 100 μm from the surface of the anode-side separator plate 50, and the width thereof was 4.5 mm. The height of the rib 56a of the anode-side seal member 56 was 300 μm from the main surface of the seal member 56. On the other hand, the thickness of the cathode-side sealing member 66 was 250 μm from the surface of the cathode-side separator plate 60, and the width thereof was 4.5 mm.

An MEA was produced in the same manner as in Example 1, except that the polymer electrolyte membrane was sized as indicated by the dotted line in FIG. 16 which was slightly smaller than the separator plate.
Using the separator plate and MEA obtained above, a laminated battery was produced in the same manner as in Example 1. This laminated battery was designated as Battery C.
A gas leak check was performed on the battery C in the same manner as in Example 1. There was no gas leakage on the air side, the fuel gas side, and the cooling water side, and it was confirmed that there was no problem with the fluid sealing properties of the stacked battery.

<< Comparative Example 2 >>
As shown in FIG. 24, an anode-side separator plate 90 provided with a seal member 96 having the same configuration as the seal member 56 except that the seal portions 56a, 59b, 59c, and 59d in the seal member 56 of FIG. It was prepared in the same manner as in On the other hand, as shown in FIG. 25, a cathode-side separator plate 100 having a seal member 106 having the same configuration as the seal member 66 except that the seal portions 66a, 69b, 69c, and 69d in the seal member 66 of FIG. It was produced in the same manner as in Example 2. A laminated battery was produced in the same manner as in Example 2 except that these separator plates were used. This laminated battery was designated as Battery D. A gas leak check was performed on the battery D in the same manner as in Example 1.

  Since the rib 96a of the seal member 96 has a portion that does not contact the electrolyte membrane (the dotted line portion in FIG. 24), when the gas pressure is 5 kPa, gas leakage is detected at those portions. Thus, it was found that the battery C of Example 2 had better sealing properties than the battery D of Comparative Example 2.

The batteries C and D are maintained at 85 ° C., and hydrogen gas humidified and heated to a dew point of 83 ° C. is supplied to the anode side, and air humidified and heated to a dew point of 78 ° C. is supplied to the cathode side. did. As a result, at the time of no load where power was not supplied to the outside, the open-circuit voltage of the battery C of Example 2 of the present invention was 50 V, and the open-circuit voltage of the battery D of Comparative Example 2 was 42.5 V. At this time, in the battery D of Comparative Example 2, it was confirmed that gas cross leak occurred.
Further, the output characteristics of the batteries C and D were examined under the conditions of a fuel utilization of 80%, an oxygen utilization of 40%, and a current density of 0.5 A / cm ² . FIG. 30 shows the evaluation results. It was found that the battery C of Example 2 had better performance than the battery D of Comparative Example 2.

  As shown in FIG. 18, the height of the rib 56a of the anode-side seal member 56 is 300 μm from the main surface of the portion 56a-1 in contact with the polymer electrolyte membrane, and the height of the portion 56a-2 not in contact with the polymer electrolyte membrane is It was 350 μm from the surface, and the portion 56a-3 connecting them had a gentle slope. Other than that was carried out similarly to Example 2, and produced the battery C2.

The battery C2 of this example and the battery C of Example 2 were subjected to the same test as in Example 1 except that only the measured pressure was changed. As a result, the leak was not measured up to 300 kPa in the battery C2, but the leak was measured out of the manifold at 200 kPa in the battery C. Thus, it was found that the battery C2 of Example 3 had better sealing properties.
This is attributable to the fact that the sealing margin at the seal portion located outside the polymer electrolyte membrane is increased by the thickness. Here, the seal interference refers to a thickness to be compressed, which is necessary for exerting a sufficient local pressure for sealing the seal portion. Further, for a portion where a step corresponding to the film thickness is generated, the sealing height is smoothly connected, so that a stable sealing allowance can be secured over the entire sealing portion, and the sealing property is improved.

An anode-side separator plate 50 and a cathode-side separator plate 60 were produced in the same manner as in Example 2. The same anode-side seal member 56 and cathode-side seal member 66 as in Example 2 were separately manufactured.
The seal members 56 and 66 were provided on the separator plates 50 and 60 by fitting the seal members 56 and 66 prepared above into the grooves 50a and 60a of the separator plates 50 and 60, respectively. At this time, the sealing member of this embodiment has a wider width than the conventional O-ring type gasket, so that the handling at the time of assembling was good.

A laminated battery was manufactured in the same manner as in Example 2, except that the anode-side separator plate 50 and the cathode-side separator plate 60 obtained above were used. This battery was designated as battery E.
A gas leak check was performed on the battery E in the same manner as in Example 1. There was no gas leakage on the air side, fuel gas side, and cooling water side, and it was confirmed that there was no problem with the fluid sealability.
The battery E was maintained at 85 ° C., and hydrogen gas humidified and heated to a dew point of 83 ° C. was supplied to the anode side, and air humidified and heated to a dew point of 78 ° C. was supplied to the cathode side. As a result, an open-circuit voltage of 50 V was obtained when no load was supplied to the outside without power.

The output characteristics of this battery E were examined under the same conditions as in Example 1. The evaluation results are shown in FIG. 31 together with the battery B of Comparative Example 1. It was confirmed that the battery E of this example had the same performance as the battery B of Comparative Example 1.
Further, in order to increase the adhesiveness between the seal member and the separator plate, an adhesive made of butyl rubber may be applied to the joint surface of the seal member of the present embodiment with the separator plate. Even when this seal member was used, performance equivalent to that of the present example was confirmed.
At this time, even if the integrated member of the seal member and the separator plate was violently vibrated, the seal member and the separator plate were not separated. In addition, it was confirmed that shock such as vibration applied at the time of assembling had no problem with an integrated product of the separator plate and the seal member.

The anode-side seal member 76 of the second embodiment shown in FIGS. 26 and 27 was provided on the anode-side separator plate 50 in the same manner as in the second embodiment.
At this time, the thickness of the anode-side seal member 76 was 100 μm from the surface of the anode-side separator plate 50, and the height of the rib 76 a provided on the seal member 76 was 300 μm from the main surface of the seal member 76.
If a part of the separator plate that does not cover the sealing member is required in the assembly process, a part of the gasket that covers substantially the entire surface is deleted, or a part where the sealing member is not formed in advance during molding is provided. You may.

A laminated battery was produced in the same manner as in Example 2 except that the above-mentioned anode-side sealing member was used. This laminated battery was designated as Battery F.
The battery F was checked for gas leakage under the same conditions as in Example 1. There was no gas leakage on the air side, fuel gas side, and cooling water side, and it was confirmed that there was no problem with the fluid sealability.
The battery F was maintained at 85 ° C., and hydrogen gas humidified and heated to a dew point of 83 ° C. was supplied to the anode side, and air humidified and heated to a dew point of 78 ° C. was supplied to the cathode side. As a result, an open-circuit voltage of 50 V was obtained when no load was supplied to the outside without power.

The output characteristics of this battery F were examined under the same conditions as in Example 1. FIG. 32 shows the evaluation results together with the battery D of Comparative Example 2. As a result, it was confirmed that the battery F of the present example had better performance than the battery D of Comparative Example 2.
Furthermore, since the main surface of the anode-side separator plate was covered with the sealing member, no short circuit occurred even if conductive foreign matter entered.

The anode-side seal member 86 shown in FIG. 28 according to the second embodiment is provided on the anode-side separator plate 50 in the same manner as in the second embodiment. At this time, the thickness of the anode-side seal member 86 provided on the side surface of the anode-side separator plate 50 was 100 μm.
A laminated battery was manufactured in the same manner as in Example 2, except that the above-mentioned anode-side sealing member 86 was used. This laminated battery was designated as Battery G.
The battery G was checked for gas leakage in the same manner as in Example 1. There was no gas leakage on the air side, fuel gas side, and cooling water side, and it was confirmed that there was no problem with the fluid sealability.

The battery G was kept at 85 ° C., and hydrogen gas humidified and heated to a dew point of 83 ° C. was supplied to the anode side, and air humidified and heated to a dew point of 78 ° C. was supplied to the cathode side. As a result, an open-circuit voltage of 50 V was obtained when no load was supplied to the outside without power.
The output characteristics of this battery G were examined under the same conditions as in Example 1. The evaluation results are shown in FIG. 33 together with the battery D of Comparative Example 2. As a result, it was confirmed that the battery G of this example had better performance than the battery D of Comparative Example 2.
In addition, since the main surface of the anode-side separator plate was covered with the seal member 86, no short circuit occurred even if conductive foreign matter entered. Furthermore, since the side surface of the anode-side separator plate 50 is covered with the sealing member 86, even if there is a conductive foreign substance on the surface of the stacked battery, a short circuit does not occur, and there is a risk of electric shock when the stacked battery is used. Performance has been reduced.

Embodiment 3
34 is a front view of a cathode separator plate of the fuel cell according to the present embodiment, FIG. 35 is a rear view thereof, and FIG. 36 is a front view of an anode separator plate.
The cathode-side separator plate 110 has a pair of oxidant gas manifold holes 111, a pair of fuel gas manifold holes 112, a pair of cooling water manifold holes 113, and four bolt holes 119 for passing fastening bolts. . On the surface of the separator plate 110 facing the cathode, there is a gas flow path 115 connected to the pair of manifold holes 111. The separator plate 110 has a cooling water flow path 114 connected to a pair of cooling water manifold holes 113 on the back surface. Separator plate 110 further has a seal member groove 116 surrounding manifold holes 113 and flow paths 114, and seal member grooves 117 and 118 surrounding manifold holes 111 and 112, respectively, on the back surface. The separator plate 110 has a pair of dummy manifold holes 113B in order to further maintain a balance with the manifold holes 113.

  The anode-side separator plate 120 has a pair of oxidant gas manifold holes 121, a pair of fuel gas manifold holes 122, a pair of cooling water manifold holes 123, a dummy manifold hole 123B, and four holes for passing fastening bolts. Bolt holes 129. On the surface of the separator plate 120 facing the anode, there is a gas flow path 124 connected to the pair of manifold holes 122. Although not shown, the separator plate 120 has a back surface, similar to the cathode-side separator plate, on the back surface, a cooling water flow path connected to the pair of cooling water manifold holes 123, and a sealing member surrounding the manifold hole 123 and the cooling water flow path. And a groove for a seal member surrounding the manifold holes 121 and 122, respectively.

  As shown in FIG. 37, the cathode-side sealing member 150 surrounds a portion of the cathode-side separator plate 110 extending from the pair of oxidizing gas manifold holes 111 to the gas flow path 115 to form a narrow strip-shaped piece 151 forming a closed loop. Have. The cathode-side sealing member 150 further includes a ring-shaped piece 152 surrounding the fuel gas manifold hole 112, a vertical piece 158 and a horizontal piece 154 connecting the piece 152 to the piece 151, and a cooling water manifold. There are interconnected ring-shaped pieces 153 and 153B surrounding the hole 113 and the dummy manifold hole 113B, respectively, and strip-shaped pieces 156 and 157 connecting ends of the pieces 153 and 153B to the piece 151. As shown in FIG. 39, the seal member 150 has a three-layer structure of an adhesive layer 161, a resin film 162, and a rubber layer 163. The piece 151 is a wedge-shaped part having a cross section in which the inside is thin and the outside is thick. The pieces 152, 153, and 153B are wedge-shaped having a cross section that is thick on the inside, that is, the manifold hole side, and thin on the outside.

The pieces 154, 156, 157 and 158 also have a wedge-shaped cross section. The thicker one may be either the inside or the outside, but it is preferable that the inside is thick and the outside is thin.
As shown in FIG. 38, the anode-side sealing member 180 has manifold holes 181, 182, 183, 183 B and 189 B communicating with the manifold holes 121, 122, 123, 123 B and the hole 129 of the anode-side separator plate 120, respectively. It has a notch 184 corresponding to the anode. As shown in FIG. 40, the seal member 180 has a three-layer structure of a pressure-sensitive adhesive layer 191, a resin film 192, and a rubber layer 193, like the seal member 150, but is entirely made of a flat plate having the same thickness.

On the cathode-side separator plate 110, the cathode-side sealing member 150 is overlaid on the surface facing the cathode, with the pressure-sensitive adhesive layer down, and pressed by hot pressing. Similarly, the anode-side separator member 120 is placed on the surface facing the anode with the anode-side sealing member 180 facing down with the adhesive layer, and pressed by hot pressing. FIGS. 41 and 42 show the cathode-side separator plate and the anode-side separator plate thus joined with the sealing member, respectively.
A unit cell is constituted by a separator plate to which these seal members are joined, sandwiching a polymer electrolyte membrane and an MEA comprising a pair of electrodes sandwiching the polymer electrolyte membrane. Between adjacent unit cells, a cooling unit is provided at a junction between the back surfaces of the cathode-side separator plate and the anode-side separator plate. Between the separator plates, O-rings are inserted into portions corresponding to the grooves 116, 117 and 118 shown in FIG. This assembling procedure will be described below.

First, an assembly jig on which guide pins are set is set, and an anode-side separator plate 120 with a seal member is placed thereon. Next, the MEA is set along the guide pins. At this time, the anode gas diffusion layer is carefully assembled so as not to run on the edge of the cutout portion 184 of the seal member 180.
There is a clearance between the guide pin set on the jig and each component to be assembled. In particular, since the dimensions of the MEA change greatly depending on the humidity of the environment in which it is assembled, it is necessary to increase the clearance. In order to assemble the MEA stably, the clearance of the guide portion is required to be 1 mm.

After setting the MEA, the cathode-side separator plate 110 is assembled. Since the separator plate is opaque, it is not possible to directly observe how the gas diffusion layer of the cathode of the MEA is in contact with the sealing member. At this time, it is desirable that the gas diffusion layer of the cathode of the MEA be set at the center of the cathode side sealing member 150. However, misalignment occurs due to accumulation of jig clearance, MEA dimensional error, and separator plate dimensional error.
In the case of a conventional flat seal member, the gas diffusion layer rides on the seal member near the assumed upper limit of the positional deviation, and the sealing property cannot be secured. If the clearance is made large in order to improve the assemblability, the gas will not be supplied to the electrode through the clearance.

  On the other hand, when the seal member having the wedge-shaped cross-section according to the present invention is used, even if the gas diffusion layer slightly rides on the low portion 163L of the seal member 150 due to dimensional deviation, the sealing is performed by the high wedge-shaped portion 163H. There is no gas leakage to the outside of the piece 151 of the sealing member 150, and the sealing performance can be ensured. Further, since the sealing member is of a wedge type, the clearance between the sealing member and the gas diffusion layer can be made large in the plane direction of the separator plate, but can be made small in the height direction. Therefore, there is no reduction in power generation performance due to gas blow-through, that is, passing through the clearance portion without passing through the gas flow path.

  As is apparent from the above description, it is preferable that the portion of the piece 151 surrounding the cathode, that is, the portion shown by oblique lines in FIG. 37 is a wedge-shaped portion having a thinner inside and a thicker outside. The other portion of the piece 151 may be wedge-shaped so that either the inside or the outside becomes thinner, but preferably has a cross-section where the inside is thin and the outside is thick, like the portion surrounding the electrode.

  In assembling a battery using the seal member according to the present invention, as described above, first, the anode-side separator plate to which the seal member is joined is placed on a jig having guide pins, and then the MEA is set along the guide pins. Then, a procedure of assembling the cathode side separator plate after that is adopted. According to this procedure, the anode gas diffusion layer can be visually and carefully assembled so as not to run on the edge of the cutout portion 184 of the seal member 180. Thus, it is possible to reduce variation in pressure loss due to an assembly error on the anode side where the utilization rate of the reaction gas is large. On the other hand, on the cathode side, the state of contact between the gas diffusion layer of the cathode and the seal member cannot be directly observed at the time of assembly. However, gas leakage due to an assembly error can be prevented by using a seal member having a wedge-shaped cross section.

25% by weight of platinum particles having an average particle size of about 30 ° were supported on acetylene black-based carbon powder. This catalyst powder and an ethanol dispersion of perfluorocarbon sulfonic acid powder were mixed, applied to one surface of a carbon nonwoven fabric having a thickness of 250 μm, and dried to form an electrode catalyst layer. Amount of platinum contained in the electrode after forming the 0.5 mg / cm ^2, the amount of perfluorocarbon sulfonic acid was 1.2 mg / cm ^2.

  The cathode and the anode having the same structure thus produced were hot-coated on both sides of the center portion of the proton conductive polymer electrolyte membrane having an area slightly larger than these electrodes so that the printed catalyst layer was in contact with the electrolyte membrane. Bonding was performed by pressing to produce an electrolyte membrane electrode assembly (MEA). As the hydrogen ion conductive polymer electrolyte membrane, a perfluorocarbonsulfonic acid thinned to a thickness of 175 μm was used. The size of the electrolyte membrane was the same as the size of the separator plate described below, and holes corresponding to the manifold holes for the fuel gas, cooling water, and oxidizing gas described later were formed in the electrolyte membrane by a punching die.

The structure of each component of the fuel cell manufactured in this example will be described below.
The cathode-side separator plate 110 and the anode-side separator plate 120 were formed in the above-described structure by forming gas passages and manifold holes by machining a 3 mm-thick airtight isotropic graphite plate. The gas flow path and the cooling water flow path have a groove width of 1.5 mm and a pitch of 3 mm. The flow path of the oxidizing gas is a serpentine type formed with seven parallel grooves, the flow path of the fuel gas is formed with four parallel grooves, and the cooling water flow path is formed of six parallel grooves.

  Next, the anode-side sealing member 180 has a 100 μm-thick polyimide film 192 having a 25 μm-thick butyl rubber adhesive layer 191 on one surface and a 125 μm-thick fluororubber layer 193 on the other surface. Was used. A portion corresponding to the manifold hole, the fastening bolt hole, and the electrode (the cutout portion 184) was cut out from the sheet with a cutting die to produce a seal member. The dimension corresponding to the electrode was such that the clearance with the electrode portion was 0.25 mm on one side.

The cathode-side sealing member 150 was produced by forming a fluoro rubber 163 on a polyimide film 162 having a thickness of 100 μm so as to surround a portion where a seal was required. The fluororubber 163 has a wedge-shaped cross section having a width of 3 mm, a higher height of 300 μm, and a lower height of 50 μm. That is, as described in the third embodiment, the piece 151 has a cross section in which the inside is thin and the outside is thick. Further, the pieces 152, 153 and 153B are made thicker on the inside and thinner on the outside. For molding of the fluororubber on the polyimide film, the polyimide film is set in a mold, the mold is closed, the fluororubber is molded at a temperature of 200 ° C. and an injection pressure of 150 kgf / cm ² , and the secondary crosslinking is performed at 200 ° C. for 10 hours. went. Thereafter, an adhesive layer 161 made of butyl rubber having a thickness of 25 μm was transferred and joined to a polyimide film, and the surface of the adhesive layer was covered with a release film made of polypropylene. The sheet was then punched out with a punching die to form portions corresponding to manifold holes, fastening bolt holes, and electrodes. The dimension corresponding to the electrode was such that the clearance with the electrode portion was 0.25 mm on one side.

  The seal members 150 and 180 thus produced were set on the separator plates 110 and 120, respectively, and the seal members were pressed against the separator plates by hot pressing. At this time, the temperature was 100 ° C., the pressing load was 2000 kgf, and the pressing time was 1 minute.

Next, as described above, an assembling jig having guide pins is prepared, and an anode-side separator plate, an MEA, and a cathode-side separator plate are sequentially assembled along the guide pins, and 50 cells are stacked in a unit cell. did. The electrode area of the MEA is 100 cm ² . This cell stack was sandwiched between stainless steel end plates via a current collector plate and an insulating plate, and fastened with a fastening rod at a fastening load of 700 kgf. At this time, as a result of confirming the fastening surface pressure between the MEA and the separator plate using pressure-sensitive paper, the surface pressure applied to the MEA was 10 kgf / cm ² . As a result, it was found that the reaction force at the seal member was 200 kgf.

A gas leak check was performed on the thus manufactured laminated battery. At this time, the leak check was performed by closing the outlet manifold of the flow path, allowing He gas to flow from the inlet manifold at a pressure of 0.5 kgf / cm ² , and evaluating the flow rate of the flowing gas at that time. There was no gas leak on the oxidizing gas side, the fuel gas side, and the cooling water side, and it was confirmed that there was no problem in the fluid sealing properties of the stacked battery.

<< Comparative Example 3 >>
An example in which a conventional flat seal member is used for sealing the oxidant gas side will be described. Example 7 is the same as Example 7 except that the seal member on the oxidant gas side is a flat plate. After 50 cells were stacked using an assembly jig in the same manner as in Example 7, a leak check was performed in the same manner. Since the fastening load was 2000 kgf and the surface pressure applied to the MEA was 10 kgf / cm ² , the fastening was performed at 2000 kgf. As a result, in some cells, a gas leaked to the outside, a cross leak from the oxidizing gas side to the fuel gas side, or both, occurred, resulting in poor sealing. The leak check conditions are the same as in the seventh embodiment.

  After performing this test, the battery of Example 7 and the battery of Comparative Example 3 were disassembled. As a result, in both batteries, the cathode gas diffusion layer of the MEA was assembled with a slight deviation from the center of the cathode sealing member. In the battery of Example 7, since the sealing portion is formed by a portion having a high wedge-shaped cross-section of the sealing member, even if the gas diffusion layer rides on the sealing member to some extent, the sealing member is kept within the range of displacement of the gas diffusion layer during assembly. It was found that the property could be secured. On the other hand, in the battery of Comparative Example 3, the gas diffusion layer and the sealing member were similarly displaced. However, in the case of the flat sealing member, even if a part of the gas diffusion layer climbed on the sealing member, the sealing property was impaired, and the sealing failure occurred. Was found to be inviting.

  Next, the cells of the battery of Comparative Example 3 having defective sealing were removed, 30 cells capable of normal operation were selected by leak check, and a 30-cell laminated battery was manufactured. This and the 50-cell laminated battery of Example 7 were evaluated for battery performance as follows.

  The fuel cell of Example 7 and the fuel cell of Comparative Example 3 were kept at 75 ° C., and humidified and heated so as to have a dew point of 70 ° C. on the anode, and humidified and heated so as to have a dew point of 60 ° C. The air thus obtained was supplied to each of the cathodes. As a result, at the time of no load in which both batteries did not output current to the outside, the battery of Example 7 obtained a battery open-circuit voltage of 50 V, and the battery of Comparative Example 3 obtained a battery open voltage of 30 V. It was confirmed that there were no problems such as cross leak and short circuit.

These cells were started to generate electricity at a fuel utilization of 80%, an oxygen utilization of 40%, and a current density of 0.3 A / cm ² . Then, the humidification of the fuel gas was kept constant at a dew point of 70 ° C., and the humidification of the air was changed in steps of 5 ° C. from 60 ° C., and power was generated for 24 hours under each condition. FIG. 44 shows the voltage stability of each battery. In the laminated battery of Comparative Example 3, the output voltage was unstable when the dew point on the oxidizing gas side was 70 ° C. or higher, and a decrease in the output voltage was confirmed at a dew point of 75 ° C. On the other hand, in the battery of Example 7, a stable output voltage was confirmed up to a dew point of 75 ° C. The pressure loss on the oxidizing gas side of the battery of Comparative Example 3 was higher than that of the battery of Example 7 by 5%, and oscillation of the pressure loss was confirmed at a dew point of 70 ° C. or higher.
When the laminated battery evaluated above was disassembled and the gas flow path of the separator plate was confirmed, in the battery of Comparative Example 3, the gas flow path of the cathode-side separator plate had more water droplets than the battery of Example 7. Existed.

<< Comparative Example 4 >>
A battery in which the clearance between the cathode-side sealing member and the gas diffusion layer in the battery of Comparative Example 3 was increased from 0.25 mm to 1.0 mm on one side. A 30-cell laminated battery having the same configuration as the battery of Comparative Example 3 was prepared except that the clearance between the gas diffusion layer and the sealing member was increased.

When this battery was evaluated under the same conditions as described above, the battery open-circuit voltage was 30 V, and the output characteristics obtained by changing the dew point of the oxidizing gas showed the results shown in FIG. In the battery of Comparative Example 4, a stable output voltage was confirmed up to a dew point of 75 ° C. as compared with the battery of Comparative Example 3. However, the absolute value of the output voltage under stable conditions was lower than that of Comparative Example 3. No oscillation of the pressure loss on the oxidizing gas side was observed.
The battery of Comparative Example 4 was disassembled after evaluation, and the gas flow path of the cathode-side separator plate was observed. As a result, the presence of water droplets equivalent to that of the battery of Example 7 was found.

  In a solid polymer electrolyte fuel cell, water generated by power generation is generated on the cathode side. In order to stably generate power in a battery, it is important to quickly and stably discharge generated water. If the generated water is not discharged stably, the supply of the reaction gas becomes unstable, and the output voltage fluctuates. In the worst case, since the reaction gas is not supplied, the battery may cause a reversal of the polarity, which may cause irreversible deterioration of the battery.

From the evaluation and analysis results of Example 7 and Comparative Examples 3 and 4, it can be seen that the clearance between the gas diffusion layer on the cathode side and the periphery of the seal member is effective for discharging the generated water and has an effect of obtaining a stable output voltage. all right.
However, it was also confirmed that if the clearance was too large, gas blow-through through the clearance portion without contributing to the electrode reaction increased, and the output voltage itself decreased. In this regard, it was confirmed that the battery of Example 7 was suitable for securing a necessary and sufficient clearance on the cathode side that did not cause performance degradation.
The sealing method having a wedge-shaped cross section used in Example 7 does not require a groove for fitting an O-ring, as compared with the sealing method using an O-ring. It goes without saying that it is possible to make the stacked battery compact by making it thinner.

  Using the same MEA, sealing member and separator plate as in Example 7, 20 cells were stacked in the same manner as in Example 7. However, as shown in Table 1, a cell stack having five patterns was prepared in which one-side clearance between the electrode and the sealing member was provided. Table 2 shows the assemblability of the cell stack of each pattern.

Each of the above cell stacks was sandwiched between end plates made of stainless steel via a current collecting plate and an insulating plate, and fastened with a fastening rod with a fastening load of 2000 kgf. At this time, as a result of confirming the fastening surface pressure between the MEA and the separator plate using pressure-sensitive paper, the surface pressure applied to the MEA was 10 kgf / cm ² .

  A gas leak check was performed on the laminated battery thus manufactured under the same conditions as in Example 7. Further, the laminated battery after the leak check was disassembled. Table 2 also shows these results.

  From this result, it is understood that the clearance between the sealing member and the gas diffusion layer is preferably 3 or more, that is, the one-side clearance (cl) is 0.25 mm or more from the viewpoint of the assembling property and the reliability of the seal. When the battery of Pattern 3 was evaluated under the same conditions as in Example 7, a battery open voltage of 20 V was obtained, and it was confirmed that there were no problems such as cross leak and short circuit. Furthermore, it was confirmed that the output voltage characteristics when the dew point on the oxidizing gas side was changed could obtain a stable high output voltage of 14 V (0.7 V per unit cell) up to a dew point of 75 ° C.

  Next, the pressure loss variation of the unit cell was evaluated based on the difference in the flow path pattern of the separator plate and the difference in the clearance pattern between the gas diffusion layer and the seal member. The method of forming the flow path, the method of manufacturing the seal member, the method of assembling the cell, and the configuration of the battery member are the same as those described above. Table 3 shows the combinations evaluated. The variation of the pressure loss is obtained by supplying a dry nitrogen gas corresponding to a reaction gas flow rate assumed when the reaction gas utilization rate is 40% at normal temperature from the inlet side manifold, and the pressure loss between the inlet side manifold and the outlet side manifold. Was measured. The evaluation results are shown in Table 4 and FIG.

  FIG. 46 is a graph in which the relationship between the clearance generated between the gas diffusion layer and the sealing member and the gas flow path is arranged by paying attention to the variation width of the pressure loss. The parameters are the length (L) of the gas flow path of the cathode-side separator plate, the hydraulic diameter of the cross-sectional area of the gas flow path (D), the number of passes of the gas flow path (P), and the hydraulic diameter of the cross-sectional area of the clearance part ( d) The ratio of the value defined by the length (l) of the clearance portion was devised and arranged. As a result, as shown in FIG. 46, it was found that the pressure loss variation tended to sharply decrease at a boundary of 0.27. Here, the gas flow path is composed of one or more grooves, and the “path” represents each groove of the gas flow path.

FIG. 43 is a model showing a clearance portion generated between the gas diffusion layer and the sealing member. A cathode-side sealing member 150 and an anode-side sealing member 180 are located on the outer periphery of the cathode 201 and the anode 202 with the polymer electrolyte membrane 203 interposed therebetween. These are sandwiched between the cathode side separator plate 110 and the anode side separator plate 120. In clearance l ₁ between the cathode 201 and the seal member 150, the clearance between the anode 202 and the seal member 120 is shown by l _2. The cross section of the clearance between the cathode 201 and the sealing member 150 is indicated by S. The hydraulic diameter on the cathode side is expressed by the following equation.
Hydraulic diameter = (area of section S) / (perimeter of section S) x 4

FIG. 47 shows output voltage characteristics of a battery M in which 50 cells having a pressure loss variation are stacked. In this laminated battery, the same separator plate as in Example 7 was used, and a flat sealing member was used. By adjusting the clearance between the gas diffusion layer and the sealing member, single cells having a variable pressure loss were selected and assembled as a stacked battery. The structure of the other members is the same as that of the seventh embodiment.
FIG. 47 also shows, as a comparative example, the output voltage characteristics of a battery N in which 50 cells each having a pressure loss variation within 0.5 kPa are stacked. From the results of the comparative examples, it was confirmed that when the pressure loss variation was small, the output voltage was uniform in each cell, and the variation was small. From this, it was confirmed that the manifold configuration and the gas flow configuration of the stacked battery had no problem in equally distributing the reaction gas to each unit cell.

  When the pressure loss variation width increased more than around 1.5 kPa, a decrease in output voltage was confirmed. This is attributable to the fact that there is a difference in the distribution of the reactant gas due to the variation in the pressure loss within the stacked battery, and the power generation capacity of the cell having a small flow rate of the reactant gas is reduced. That is, it was confirmed that it is effective to reduce the pressure loss variation of the unit cell incorporated in the stacked battery within 1.5 kPa to increase the output and stabilize the performance of the stacked battery.

  The relationship between the output voltage characteristics and the pressure drop variation in the stacked battery, and the parameters discussed above (the flow path length and the hydraulic diameter of the flow path cross-sectional area, the number of flow paths and the hydraulic diameter of the cross-sectional area of the clearance section, and the hydraulic diameter of the clearance section) From the relationship between the ratio defined by the length), that is, ((l / d) / (L / D / P × 2)) and the pressure loss variation in the unit battery, a clearance satisfying the following expression (3) It was found that securing was important.

    0.27 <(l / d) / (L / D × 2 / P) (3)

From this equation, it is defined that the hydraulic diameter d of the clearance between the sealing member and the gas diffusion layer needs to satisfy equation (1).

    d <(D × l × P) /0.54L (1)

According to the results of this example, one-side clearance cl between the sealing member and the gas diffusion layer is required to be 0.25 mm or more from the viewpoint of assemblability and seal reliability. It is important for the hydraulic diameter d of the clearance to secure a clearance satisfying the expression (1).
Although the configuration satisfying the above items may be any shape, the configuration of the seal member having the wedge cross section applied in Example 7 is preferable, and it is preferable to use this for the cathode-side seal member.

  Using the same MEA, sealing member and separator plate as in Example 7, 20 cells were stacked in the same manner as in Example 7 to produce eight types of cell stacks. In these cell stacks, the clearance between the electrode and the sealing member is different, and therefore, the pressure loss Pc generated in the clearance and the pressure loss Pf generated in the gas flow path of the separator plate are different as shown in Table 5. . The pressure loss ratio Pc / Pf was designed to be the same for the anode and the cathode in the same type of cell stack. In the cell stacks g and h, the gas flow path pattern was the same as the other cell stacks, but the cross-sectional area of the flow path was increased.

  Here, the pressure loss generated in the clearance section and the gas flow path was measured in advance for each cell of each type of cell stack. These were defined as pressure loss Pc occurring in the clearance portion of the laminated battery and pressure loss Pf occurring in the gas flow path of the separator plate. Specifically, the pressure loss variation of the single cell was evaluated based on the difference in the flow path pattern of the separator plate and the difference in the clearance pattern between the gas diffusion layer and the seal member. A pressure inlet for measurement was provided on the gas inlet and outlet sides of the cell so that pressure could be measured, and pressure loss was measured. When measuring the pressure in the clearance, a portion corresponding to the electrode and the gas diffusion layer in the gas flow path of the separator plate was filled with a silicone adhesive. When measuring the pressure in the gas flow channel, the clearance and the gas diffusion layer were filled with a silicone adhesive. The pressure loss was measured by supplying a dry nitrogen gas corresponding to a reaction gas flow rate assumed at a normal temperature when the reaction gas utilization rate was 40% from an inlet side manifold.

Each of the above cell stacks was sandwiched between end plates made of stainless steel via a current collecting plate and an insulating plate, and fastened with a fastening rod with a fastening load of 2000 kgf. At this time, as a result of confirming the fastening surface pressure between the MEA and the separator plate using pressure-sensitive paper, the surface pressure applied to the MEA was 10 kgf / cm ² .
A gas leak check was performed on the thus-produced laminated battery under the same conditions as in Example 1. As a result, there was no problem in the sealing performance in any cell stack.

Next, each cell stack was generated, and the voltage stability at that time was evaluated. The results are also shown in Table 5.
From this result, it can be seen that the stability of the cell voltage greatly changes when the ratio of the pressure loss Pc of the clearance portion to the pressure loss Pf of the gas flow passage portion is 0.9.
Originally, the pressure loss in the clearance is large, that is, the value of Pc / Pf is large, and therefore, the design is made such that the amount of gas flowing through the clearance is small. When the pressure loss of the clearance is small, that is, when the value of Pc / Pf is small, the gas required for power generation passes through the clearance, and it is difficult to flow into the gas flow path that should flow. As a result, the gas required for power generation is not supplied to the electrodes, and the voltage becomes unstable.

  The present inventors have found that the fuel cell can be operated even when the value of Pc / Pf is small to some extent. That is, when the polymer electrolyte fuel cell generates power, the gas generally contains moisture. It is assumed that some of them also become droplets. Therefore, the gas flow exhibits a two-layer flow state. When the ratio Pc / Pf of the pressure loss of the clearance portion to the pressure loss of the gas flow passage portion is small, and the gas is a dry gas, the above-described two-layer structure can be obtained even under a condition where a smaller amount of gas flows than the amount of power generation. In a flowing state, Pc increases. For this reason, the amount of gas passing through the clearance decreases, and operation becomes possible.

  As described above, the present inventors have found that the region where the operation can be performed practically can be arranged by the ratio of the pressure loss Pc of the clearance portion to the pressure loss Pf of the gas passage portion. That is, it was found that 0.9 <Pc / Pf was effective.

  The polymer electrolyte fuel cell of the present invention exhibits excellent airtightness with a compact sealing member, is highly reliable, and can be manufactured at low cost. Therefore, it can be used for a portable power supply, a power supply for an electric vehicle, a home cogeneration system, and the like.

It is a front view of the anode side separator board of Embodiment 1 of the present invention. It is a rear view of the same separator plate. It is a front view of the cathode side separator board of Embodiment 1 of the present invention. It is a rear view of the same separator plate. It is a front view of the compound member for anode side seals of Embodiment 1 of the present invention. FIG. 6 is an enlarged sectional view taken along line 6-6 in FIG. It is a front view of the composite member for cathode side seals of Embodiment 1 of the present invention. FIG. 8 is an enlarged sectional view taken along line 8-8 in FIG. 7. FIG. 4 is a front view of another composite member for an anode-side seal according to the first embodiment of the present invention. FIG. 4 is a front view of still another anode-side sealing composite member according to Embodiment 1 of the present invention.

It is a principal part longitudinal cross-sectional view of the laminated battery of this invention. FIG. 12 is an enlarged sectional view of the vicinity of a seal member of the laminated battery in FIG. 11. It is an expanded sectional view near the O-ring type sealing member of the conventional laminated battery. It is a front view of the anode side separator board of Embodiment 2 of the present invention. It is a front view of the cathode side separator board of Embodiment 2 of the present invention. It is a front view of the anode side separator plate provided with the seal member of Embodiment 2 of the present invention. FIG. 17 is an enlarged cross-sectional view taken along line 17-17 of FIG. FIG. 18 is an enlarged sectional view of an anode-side separator plate provided with a seal member according to a modification of the second embodiment, taken along a line corresponding to line 18-18 in FIG. It is a front view of the cathode side separator plate provided with the seal member of Embodiment 2 of the present invention. FIG. 20 is an enlarged sectional view taken along line 20-20 of FIG.

FIG. 21 is an enlarged cross-sectional view of an anode-side separator plate provided with a seal member according to another modification of the second embodiment, taken along a line corresponding to line 21-21 in FIG. FIG. 17 is a view illustrating first and second anode-side seal portions in the anode-side seal member of FIG. 16. FIG. 20 is a diagram illustrating first and second cathode-side seal portions in the cathode-side seal member of FIG. 19. 9 is a front view of an anode-side separator plate of Comparative Example 2. FIG. 9 is a front view of a cathode-side separator plate of Comparative Example 2. FIG. FIG. 13 is a front view of another anode-side separator plate according to the second embodiment of the present invention. It is an expanded sectional view near the rib of the end part of the same separator board. It is an expanded sectional view near the rib of the edge part of yet another anode side separator plate of Embodiment 2 of the present invention. 4 is a graph showing output characteristics of the stacked batteries of Example 1 and Comparative Example 1. 9 is a graph showing output characteristics of the laminated batteries of Example 2 and Comparative Example 2.

FIG. 31 is a graph showing output characteristics of the laminated batteries of Example 3 and Comparative Example 1. 9 is a graph showing output characteristics of the laminated batteries of Example 4 and Comparative Example 2. 9 is a graph showing output characteristics of the laminated batteries of Example 5 and Comparative Example 2. It is a front view of the cathode side separator of Embodiment 3 of the present invention. It is a rear view of the same cathode side separator plate. It is a front view of the anode side separator of Embodiment 3 of the present invention. It is a front view of the cathode side seal member of Embodiment 3 of the present invention. It is a front view of the anode side seal member of Embodiment 3 of the present invention. FIG. 38 is an enlarged sectional view taken along line 39-39 of FIG. 37. FIG. 40 is an enlarged sectional view taken along line 40-40 of FIG. 39.

It is a front view of the cathode side separator which combined the seal member of Embodiment 3 of the present invention. It is a front view of the anode side separator which combined the seal member of Embodiment 3 of the present invention. FIG. 3 is a model diagram showing a clearance portion generated between a gas diffusion layer and a sealing member. FIG. 9 is a diagram illustrating output voltage characteristics of the fuel cells of Example 7 and Comparative Example 3 of the present invention. FIG. 13 is a diagram illustrating output characteristics of the fuel cells of Example 7 of the present invention and Comparative Example 4. FIG. 13 is a diagram illustrating a relationship between parameters regulating a separator and a seal member and pressure loss variation according to a seventh embodiment of the present invention. FIG. 14 is a diagram showing output characteristics of the fuel cells of Example 8 and Comparative Example 4 of the present invention.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Hydrogen ion conductive polymer electrolyte membrane 2a Anode 2b Cathode 4a, 4b Polyimide film 5a, 5b Adhesive layer 10, 50 Anode side separator plate 20, 60 Cathode side separator plate 12, 22, 32, 42, 52, 62 Fuel gas Manifold holes 13, 23, 33, 43, 53, 63 Oxidant gas manifold holes 12b, 23b, 52b, 63b Gas flow paths 12c, 23c, 52c, 63c Communication gas flow paths 36, 56, 76 Anode side seal Member 36a, 56a, 76a Rib 30 Composite member for anode side seal 40 Composite member for cathode side seal 46, 66 Cathode side seal member 50a, 60a Groove for seal member

Claims (15)

(1) a hydrogen ion conductive polymer electrolyte membrane, and a membrane electrode assembly comprising an anode and a cathode sandwiching the polymer electrolyte membrane,
(2) an anode-side separator plate having a pair of fuel gas manifold holes and oxidizing gas manifold holes, and a gas flow passage connected to the fuel gas manifold holes and supplying and discharging fuel gas to and from the anode;
(3) A cathode-side separator plate having a pair of fuel gas manifold holes and a pair of oxidant gas manifold holes, and a gas flow path connected to the oxidant gas manifold holes to supply / discharge the oxidant gas to / from the cathode. ,
(4) an anode-side sealing member provided on the anode-side surface of the anode-side separator plate; and (5) a cathode-side sealing member provided on the cathode-side surface of the cathode-side separator plate,
(6) A cell constituted by sandwiching the membrane electrode assembly under pressure between an anode-side separator plate and a cathode-side separator plate, and the anode-side sealing member, the cathode-side sealing member, and the polymer electrolyte membrane cooperate with each other. Having an anode-side gas seal portion for preventing gas from leaking to the outside from the fuel gas flow channel and a cathode-side gas seal portion for preventing gas from leaking to the outside from the oxidant gas flow channel,
(7) The two gas seal members have a rib having a top portion linearly contacting the seal portion in a corresponding portion of the two gas seal portions, and the other surface contacting the seal portion in a planar manner. A polymer electrolyte fuel cell, comprising: The polymer electrolyte membrane has a pair of fuel gas manifold holes and a pair of oxidant gas manifold holes,
The anode-side seal member has a first anode-side seal portion surrounding the anode and the outer periphery of each manifold hole to form one closed loop, and a second anode-side seal portion separating the anode from each manifold hole. And
The cathode-side seal member has a first cathode-side seal portion surrounding the outer periphery of the cathode and each manifold hole to form one closed loop, and a second cathode-side seal portion separating the cathode from each manifold hole. And
In each of the seal portions, the two seal members are sandwiched between the separator plates and pressed against the polymer electrolyte membrane, and one of the seal members has a top portion in linear contact with the polymer electrolyte membrane at the pressed portion. The polymer electrolyte fuel cell according to claim 1, further comprising a rib, wherein the other sealing member is in planar contact with the polymer electrolyte membrane. The polymer electrolyte membrane has a pair of fuel gas manifold holes and a pair of oxidant gas manifold holes,
A first anode-side seal portion surrounding the outer periphery of the anode and each manifold hole to form a closed loop, and a second anode-side seal separating the anode from the oxidant gas manifold hole; Part
The cathode side sealing member surrounds the outer periphery of the cathode and each of the manifold holes to form a single closed loop, and a second cathode side sealing portion for isolating the cathode from the fuel gas manifold hole. Has,
In each of the seal portions, the two seal members are sandwiched between the separator plates and pressed against the polymer electrolyte membrane, and one of the seal members has a top portion in linear contact with the polymer electrolyte membrane at the pressed portion. The polymer electrolyte fuel cell according to claim 1, further comprising a rib, wherein the other sealing member is in planar contact with the polymer electrolyte membrane. The hydrogen ion conductive polymer electrolyte membrane has a size sufficient to cover the anode and the cathode, but has a size not in contact with each of the manifold holes,
A first anode-side sealing portion surrounding the outer periphery of the anode and the fuel gas manifold hole to form one closed loop, and an outer periphery of the polymer electrolyte membrane together with the first anode-side sealing portion; And a second anode-side seal portion surrounding the anode, wherein the first anode-side seal portion is in contact with the polymer electrolyte membrane at a portion surrounding the anode,
A first cathode-side seal portion surrounding the outer periphery of the cathode and the oxidant gas manifold hole to form one closed loop; and the first cathode-side seal portion together with the polymer electrolyte membrane. A second cathode-side sealing portion surrounding the outer periphery, wherein the first cathode-side sealing portion is in contact with the polymer electrolyte membrane at a portion surrounding the cathode;
The respective seal portions are located at positions corresponding to each other except for inevitable portions, and the two seal members are sandwiched between the two separator plates in the seal portion or directly through a polymer electrolyte membrane. The sealing member has a rib having a top portion linearly contacting the polymer electrolyte membrane or the other sealing member at the pressure contact portion, and the other sealing member is in planar contact with the portion. Item 7. The polymer electrolyte fuel cell according to Item 1.   The one seal member is configured such that a portion of the first seal portion not in contact with the polymer electrolyte membrane and a height of a rib in the second seal portion are in contact with the polymer electrolyte membrane in the first seal portion. 5. The polymer electrolyte fuel cell according to claim 4, wherein the height is higher than the height of the portion.   2. The polymer electrolyte fuel cell according to claim 1, wherein the ribs of the one sealing member are wedge-shaped and have a cross section that is thinner on the inside and thicker on the outside in a portion surrounding the anode or the cathode. The one sealing member is a cathode side sealing member, and the cathode side sealing member is
(A) a band-shaped first piece surrounding a flow path of the oxidizing gas and a pair of manifold holes connected thereto to form a closed loop;
(B) a pair of band-shaped second parts surrounding the pair of fuel gas manifold holes to form a closed loop, and (c) a band-shaped second part connecting the first part and the second part. (D) the first part is a rust type having a thinner inside and a thicker outer part, and the second part is also a rust having a thicker inside and a thinner outside. 7. The polymer electrolyte fuel cell according to claim 6, which is of a type.   2. The seal member according to claim 1, wherein the sealing member has a three-layer structure including a resin film, a pressure-sensitive adhesive layer provided on the separator plate side of the resin film, and a rubber layer provided on a side opposite to the pressure-sensitive adhesive layer. Molecular electrolyte fuel cell.   2. The polymer electrolyte fuel cell according to claim 1, wherein a ratio Pc / Pf of a pressure loss Pc based on a clearance between the electrode and the gas seal member to a pressure loss Pf generated in a gas flow path corresponding to the electrode is larger than 0.9. . The one-side clearance cl generated between the cathode surrounding portion of the cathode-side sealing member and the cathode and the hydraulic diameter d of the clearance are expressed by the following equation (1):

d <(D × l × P) /0.54L (1)
However,
l: Length of one-side clearance part d: Hydraulic diameter of one-side clearance part L: Length of gas flow path per pass of cathode-side separator plate D: Hydraulic diameter of gas flow path per pass of cathode-side separator plate P: Number of gas flow paths per cathode-side separator plate Hydraulic diameter d = (Cross-sectional area of clearance section) ÷ (Perimeter of cross-sectional area of clearance section) × 4

The polymer electrolyte fuel cell according to claim 6, which satisfies the following. Further, one-side clearance cl is expressed by the following equation (2):
0.25mm <cl (2)
The polymer electrolyte fuel cell according to claim 10, which satisfies the following.   The polymer electrolyte fuel cell according to claim 1, wherein at least one main surface of the anode-side separator plate and the cathode-side separator plate is covered with a seal member.   2. The polymer electrolyte fuel cell according to claim 1, wherein said seal member is formed on said separator plate.   The polymer electrolyte fuel cell according to claim 1, wherein the seal member is fitted to the separator plate.   The polymer electrolyte fuel cell according to claim 1, wherein the seal member is adhered to the separator plate.

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