JP2000090956A - Polymer electrolyte fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polymer electrolyte fuel cell capable of easily assembling a fuel cell, applying a uniform tightening pressure to each cell, and easily performing maintenance work. To provide. SOLUTION: An electrode-electrolyte assembly 42 in which a pair of gas diffusion electrodes 46, 46 are joined to both surfaces of a solid polymer electrolyte membrane 44 is provided with a convex sandwiching body 52 having a gas channel 52e and a gas channel 54e. And the adjacent convex-type holding body 52 and the concave-type holding body 54 are fastened to each other by screwing means using screws.
And Further, by repeating this process, the polymer electrolyte fuel cell 4 in which a predetermined number of unit cells 50 are stacked several times
Get 0.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymer electrolyte fuel cell, and more particularly, to a polymer electrolyte fuel cell suitable for a vehicle-mounted power source, a stationary small generator, and the like.

[0002]

2. Description of the Related Art A polymer electrolyte fuel cell uses a polymer electrolyte membrane (hereinafter simply referred to as "electrolyte membrane") as an electrolyte.
Fuel cells that use high power density, have a simple structure, have a relatively low operating temperature, and are quiet. Or it is used as a military power supply. In addition, fuel cells, which use hydrogen as fuel, do not emit nitrogen oxides and carbon dioxide gas in essence, and have recently attracted attention as low-pollution power sources for automobiles. is there.

FIG. 8 shows an example of the basic structure of a polymer electrolyte fuel cell. In FIG. 8, a unit cell 2 serving as a power generation unit of a polymer electrolyte fuel cell includes an electrode / electrolyte assembly 10 in which a pair of gas diffusion electrodes 14 and 16 are bonded to both surfaces of an electrolyte membrane 12 by separators 18 and 18. It has a sandwiched structure.

The electrolyte membrane 12 generally has a thickness of 50 to 200 μm represented by a perfluorosulfonic acid membrane known under the trade name of Nafion (registered trademark, manufactured by DuPont).
m fluorine-based electrolyte membrane is used.

The gas diffusion electrodes 14 and 16 are made of a porous catalyst layer (not shown) made of carbon particles carrying an electrode catalyst such as platinum and an electrolyte, and a porous material through which gas can diffuse. It is composed of two layers of a diffusion layer (not shown).

Further, the separators 18 are generally made of dense graphite which has high current collecting performance and is stable even in an oxidized steam atmosphere. Also, the separator 18,
18 has a peak 18a for supplying electrons to the gas diffusion electrodes 14 and 16, and a groove 18b for supplying a substance such as gas or water.

In a state where loads are connected to both ends of the unit cell 2 having such a structure, a gas containing hydrogen such as a reformed gas flows to one gas diffusion electrode 14 (fuel electrode) side, and the other gas diffusion electrode 14 (fuel electrode). When a gas containing oxygen such as air flows on the electrode 16 (air electrode) side, water is generated from hydrogen and oxygen, and a change in free energy at that time is caused by a change in the separator 1 disposed at both ends of the cell 2.
It is extracted directly from 8, 18 as electric energy.

Meanwhile, the electromotive force of the unit cell 2 shown in FIG. 8 is about 1 V, and cannot be put to practical use as it is. Therefore, usually, in order to obtain a high output voltage, several hundred cells are stacked in series, and a fuel, air, and a device that collectively enters and exits fuel, air, and cooling water are attached thereto, and the fuel contained in a container is mounted. It is practically used as an assembly of cells, a so-called fuel cell stack.

FIG. 9 shows an example of a stack structure. FIG.
In the fuel cell stack 20, in the fuel cell stack 20, several hundred cells shown in FIG. 8 are stacked, and a cooling plate 22 for maintaining the cells 2 at an optimum temperature is arranged every few cells. It has a structure in which fastening plates 24 and 24 are arranged above and below the battery 2.

Further, between the upper and lower ends of the stacked unit cells 2 and the clamping plates 24, 24, there are provided terminal plates 30, 30 for taking out generated electricity, and an insulating plate 32 for ensuring insulation. , 32 are arranged. Further, fuel manifolds 34, 34 for supplying fuel gas and air manifolds 36, 36 for supplying air are provided on side surfaces of the fuel cell stack 20.

Are sandwiched between two clamping plates 24, 24, a plurality of bolts 26, 26 are passed through upper and lower clamping plates 24, 24, and nuts 28, 28
Are assembled together to assemble the fuel cell stack 20.

[0012]

However, as shown in FIG. 9, a conventional fuel is obtained by laminating a number of members such as an electrode-electrolyte assembly, a separator, a terminal plate, a cooling plate and the like, and tightening them together with bolts. The battery stack has a problem that many steps are required for assembling and the manufacturing cost is increased.

Further, in order to prevent gas leakage from the separator and to ensure electrical contact between the electrolyte membrane and the gas diffusion electrode, the electrode / electrolyte assembly and the separator are uniformly tightened. Although it is necessary to tighten with pressure, the method of simultaneously tightening fuel cell stacks in which several hundred cells are stacked causes variations in the tightening pressure for each cell, making uniform tightening difficult. was there.

Furthermore, since the fuel cell stack is formed by stacking cells in series, if an abnormality occurs in one cell, the entire fuel cell stack will not operate. In that case, remove the bolt and disassemble the entire fuel cell stack,
After replacing the abnormal cell with a normal cell, it is necessary to reassemble the entire fuel cell stack, and there has been a problem that maintenance work is complicated.

An object of the present invention is to provide a solid polymer fuel capable of easily performing an assembling operation, applying a uniform tightening pressure to each cell, and easily performing a maintenance operation. It is to provide a battery.

[0016]

In order to solve the above-mentioned problems, a polymer electrolyte fuel cell according to the present invention comprises an electrode-electrolyte assembly in which a pair of gas diffusion electrodes is joined to both surfaces of a polymer electrolyte. The invention is characterized in that it comprises a holding body that holds the electrode / electrolyte assembly and has a gas flow path constituting a cell, and mechanical fastening means for individually connecting the adjacent holding bodies. Things.

The mechanical fastening means is not particularly limited as long as it is a means capable of reversibly fastening and separating adjacent holding bodies (also serving as separators). Body with male and female threads, without
A screwing means for fastening by screwing is preferable. Also,
A fitting means may be provided in which a projection is provided on one holding body, a groove is provided on the other holding body which engages with the projection, and the projection is engaged with the groove to fasten the fitting.

According to the polymer electrolyte fuel cell according to the present invention having the above-described structure, the fastening operation of the unit cell is performed by holding one electrode / electrolyte assembly by a pair of holding bodies and using mechanical fastening means. This is performed by fastening the holding members.

Even when several hundred cells are stacked, this operation is repeated, and the electrode / electrolyte assembly is arranged between the already fastened sandwich and a new sandwich.
The already fastened holding body and the new holding body may be fastened by mechanical fastening means and integrated.

According to the present invention, one fastening step allows one
Since the electrode / electrolyte assembly is fastened, the assembly of the fuel cell becomes easier, the number of steps can be reduced, and the polymer electrolyte fuel cell can be manufactured at low cost as compared with the conventional method. .

Further, since the electrode-electrolyte assembly is fastened each time, each electrode-electrolyte assembly can be tightened at a uniform pressure, and the difference in characteristics between cells can be reduced. Further, if an abnormality occurs in some of the cells after assembling the fuel cell stack, the fastening of the holding body at the site where the abnormality has occurred is released, and only the electrode / electrolyte assembly in which the abnormality has occurred is removed. Maintenance work is facilitated.

[0022]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a first embodiment of the present invention.
FIG. 2 is an exploded cross-sectional view of the polymer electrolyte fuel cell according to the embodiment. In FIG. 1, a polymer electrolyte fuel cell 40 includes:
An electrode / electrolyte assembly 42, a holding body 52 having protrusions 52 b at both ends (hereinafter, referred to as a “convex holding body”) 52,
A holding body 54 (hereinafter, referred to as a “concave holding body”) 54 having concave portions 54b at both ends and a terminal plate 56 are provided.

The convex holding members 52 and the concave holding members 54 are arranged alternately in the direction in which the electrode / electrolyte joints 42 are stacked. In addition, the convex portion 52b of the adjacent convex holding body 52
And the concave portion 54b of the concave holding member 54 can be fastened and integrated by mechanical fastening means. In the polymer electrolyte fuel cell 40 illustrated in FIG. 1, screwing means by screwing is used as mechanical fastening means.

Further, the electrode / electrolyte assembly 42 is formed such that the front end surface of the convex portion 52b of the convex holding member 52 and the concave portion 5 of the concave holding member 54 are formed.
4b is sandwiched between the bottom surface and the bottom surface, and the convex sandwiching body 52, the electrode / electrolyte assembly 42, and the concave sandwiching body 5
4 constitute one cell 50. Further, a terminal plate 5 for taking out electricity generated by the electrode-electrolyte assembly 42 is provided on the projection 52 of the projection-type holding body 52 provided at both ends.
6 is attached.

Although the solid polymer fuel cell 40 illustrated in FIG. 1 has a structure in which four single cells 50 are stacked, the same applies when five or more single cells 50 are stacked. The convex-type holding body 52 and the concave-type holding body 54 may be alternately arranged according to the number of stacked cells 50, and the electrode-electrolyte assembly 42 may be disposed between the convex-type holding body 52 and the concave-type holding body 54. .

As shown in FIG. 2, the electrode / electrolyte assembly 42 has a gas diffusion electrode 46 joined to both surfaces of an electrolyte membrane 44. As the electrolyte membrane 44, various electrolyte membranes having proton conductivity can be used, and are not particularly limited. Generally, a fluorine-based electrolyte membrane having a thickness of 50 to 200 μm represented by a perfluorosulfonic acid membrane is used.

The perfluorosulfonic acid membrane is a copolymer of perfluorovinyl ether having a sulfonic acid group as an electrolyte group and tetrafluoroethylene, has high proton conductivity, and has excellent oxidation resistance. Therefore, it has been awarded as an electrolyte membrane for polymer electrolyte fuel cells.

The gas diffusion electrode 46 has a porous catalyst layer 46a made of carbon particles carrying an electrode catalyst such as platinum and an electrolyte such as a perfluorosulfonic acid polymer.
And a porous diffusion layer 46b made of carbon paper, carbon cloth, or the like.

As shown in FIG. 3, the convex holding body 52 includes a support frame 52a, a gas permeable body 52g, and a lead wire 52h. The support frame 52a serves as a base material of the convex holding member 52. Both ends of the disk-shaped base material have convex portions 5a.
2b is formed.

A concave holding member 54 is provided on the outer surface of the convex portion 52b.
Male screw is provided for fastening. Further, a lead wire burying groove 52c is provided on an end face of each convex portion 52b, and the lead wire burying groove 52c is connected to a lead wire drawing hole 52d provided on a side surface of the support frame 52a.

A gas passage 52e penetrating in the radial direction is provided inside the support frame 52a.
A reaction gas can be flowed into 2e. further,
At the center of the support frame 52a, a cylindrical through hole 52f is provided along the axial direction so as to be orthogonal to the gas flow path 52e.

Here, for the support frame 52a, a material having heat resistance and insulation that does not deform even in the operating temperature range (around 80 ° C.) of the polymer electrolyte fuel cell 40 is used. Specifically, polytetrafluoroethylene is a preferred example. The need for heat resistance is to suppress the deformation of the support frame 52a and to prevent a reduction in the tightening pressure of the electrode / electrolyte assembly 42 and a reduction in the sealing performance of the reaction gas.

The reason why insulation is required is to obtain a high output voltage. That is, in order to obtain a high output voltage, it is necessary to connect the cells 50 in series. However, as described later, in the polymer electrolyte fuel cell 40 shown in FIG. ), (+-), (-+) ...
This is because, if a conductor is used as the support frame 52a, the same poles are connected and the fuel cell 40 is short-circuited.

When a high output voltage is not required, a single cell 50 is connected in parallel by using a conductor such as stainless steel for a part of the support frame 52a and using an insulator for the other part. May be configured.

The gas permeable body 52g has a cylindrical shape and is buried in the through hole 52f of the support frame 52a. In addition, the gas permeable body 52g has a gas permeable, convex holding body 5
A material having strength and insulating properties that does not cause crushing when the electrode / electrolyte assembly 42 is sandwiched between the second and concave holding members 54 is used. Specifically, a ceramic porous body such as zirconia is a preferred example.

The reason why gas permeability is required is that the support frame 52
The reaction gas flowing through the gas flow path 52e of FIG.
This is for supplying to the electrode / electrolyte assembly 42 disposed on both surfaces of the support frame 52a via 2 g.

Accordingly, in the polymer electrolyte fuel cell 40 illustrated in FIG. 1, the support frame 52a does not have a function as a separator for preventing the reaction gas from being mixed, and the electrode-electrolyte assembly 42 is As a function.

Further, the strength is required because the electrode-electrolyte assembly 42 is formed by the convex holding body 52 and the concave holding body 54.
This is because a predetermined tightening pressure is applied to the electrode / electrolyte assembly 42 when sandwiching. That is, if the strength of the gas permeable body 52g is low, the tightening pressure cannot be increased, and gas leakage of the reaction gas may occur or the electrolyte membrane 4
4 and the gas diffusion electrode 46 have insufficient electrical contact,
Power generation efficiency decreases.

Further, the reason why insulation is required is to connect the cells 50 in series and secure a high output voltage as in the case of the above-described support frame 52a. However, when a high output voltage is not required, as in the case of the support frame 52a, a part of the gas permeable body 52g is made of a gas permeable conductor such as a porous metal body or a metal mesh laminate, and the cell 50 May be connected in parallel.

It should be noted that the gas permeable body 52g only needs to be capable of supplying a reaction gas to the electrode / electrolyte assembly 42,
The shape of the gas permeable body 52g is not limited to a cylindrical ceramic porous body as illustrated in FIG.

For example, as the gas permeable body 52g, a gas permeable body in which a through hole is provided on the side surface of a cylindrical ceramic porous body along the gas flow direction may be used. Providing a through-hole along the gas flow direction has the advantage that pressure loss can be reduced. In addition, a dense material is used as the gas permeable body 52g, and it has a so-called rib shape in which a number of grooves penetrating along the gas flow direction are provided. The electrode / electrolyte joint body 42 is supported at the tip of the peak. You may do it.

The lead wire 52h is brought into contact with the gas diffusion electrode 46 joined to the electrolyte membrane 44, so that the electrode 52
This is for extracting electricity generated by the electrolyte joined body 42, and is buried in a lead wire burying groove 52c provided on an end face of the convex portion 52b of the support frame 52a. The end of the lead wire 52h is drawn out of the support frame 52a from a lead wire drawing hole 52d provided on a side surface of the support frame 52a.

As a material of the lead wire 52h, a material having excellent corrosion resistance is used. Specifically, stainless steel,
A preferable example is Sn or a Sn alloy or a lead wire made of a metal such as stainless steel or copper coated with Sn or a Sn alloy.

The reason why corrosion resistance is required is that the reaction gas supplied to the polymer electrolyte fuel cell 40 is usually formed by the electrolyte membrane 4.
4 is humidified to replenish water,
h is exposed to an oxidizing water vapor atmosphere, but when the lead wire 52h is oxidized and passivated by the oxidizing water vapor, the contact resistance with the gas diffusion electrode 46 increases, and the power generation efficiency decreases.

As shown in FIG. 4, the concave holding member 54 includes a support frame 54a, a gas permeable member 54g, and a lead wire 54h. The support frame 54a serves as a base material of the concave holding member 54, and a concave portion 54 is provided on both end surfaces of the disk-shaped base material.
b is formed. Also, on the inner surface of the concave portion 54b,
A female screw is provided and screwed with a male screw formed on the outer surface of the convex portion 52a of the convex holding member 52, thereby mechanically fastening and integrating the concave holding member 54 and the convex holding member 52. I can do it.

The inner diameter of the concave portion 54b of the support frame 54a is slightly larger than the outer diameter of the electrode / electrolyte joint 42 so that the electrode / electrolyte joint 42 can be accommodated in the concave portion 54b.

Further, the concave holding member 54 and the convex holding member 52
Is formed, a space is formed between the bottom surface of the concave portion 54b and the tip end surface of the convex portion 52b, and the height of the space is fixed to the electrode / electrolyte assembly 42 sandwiched in the space by a predetermined amount. The electrode / electrolyte assembly 42 is pressed so that pressure is applied.
It is slightly smaller than the height.

In addition, a lead wire burying groove 54c is provided on the bottom surface of the concave portion 54b of the support frame 54a, and is connected to a lead wire drawing hole 54d provided on the side surface of the support frame 54a. Is a point where a gas flow passage 54e penetrating along the radial direction is provided, a point where a through hole 54f is provided along the axial direction, a support frame 54a
The point that polytetrafluoroethylene is preferable as the material of the support member 52 is the same as that of the support frame 52 a of the convex holding member 52.

In the through hole 54f of the support frame 54a,
The point that the gas permeable body 54g is embedded
g is preferably a ceramic porous body such as zirconia, and the lead wire burying hole 54c has a lead wire 54h.
Is embedded, and the material of the lead wire 54h is stainless steel, Sn or Sn alloy wire, or stainless steel,
It is the same as the convex holding body 52 in that a metal wire such as copper coated with Sn or a Sn alloy is suitable.

As shown in FIG. 5, the terminal plate 56 is provided with a female screw 56a so that it can be screwed with the convex portion 52b of the convex holding member 52 disposed at both ends of the stacked unit cells 50. . In addition, a conductive material such as stainless steel or copper is used for the terminal plate 56.

It is sufficient that the terminal plate 56 can take out the electricity generated by the electrode / electrolyte joints 42. Therefore, the terminal plate 56 does not necessarily need to be screwed with the convex holding member 52, and may be simply fitted. good. In addition, the cell 50
When one end of the laminate is a concave holding member 54, a male screw provided with a female screw of the concave portion 54b, or a male screw provided with a convex portion that can be fitted may be used as the terminal plate 56. good.

Next, the polymer electrolyte fuel cell 4 shown in FIG.
The assembly procedure of No. 0 will be described. First, the concave holding body 54 in which the gas permeable body 54g and the lead wire 54h are embedded
The electrode / electrolyte assembly 42 is accommodated in the concave portion 54b of FIG. Next, the convex portion 52b of the convex holding body 52 in which the gas permeable body 52g and the lead wire 52h are buried is also inserted into the concave holding body 54.
And the protrusion 52b and the recess 54b may be screwed together.

Thus, the electrode-electrolyte assembly 42 is
A predetermined tightening pressure is evenly applied by the tip surface of the convex portion 52b and the bottom surface of the concave portion 54b. At this time, the lead wires 52 embedded in the lead wire embedding holes 52c and 54c are
h, 54h and the gas diffusion electrodes 46, 46 of the electrode / electrolyte assembly 42 come into contact to form one unit cell 50.

The same applies to the fastening operation of the second and subsequent unit cells 50, and the other recess 5 of the recessed clamping body 54 already fastened is used.
4b, the electrode-electrolyte assembly 42 is housed, and the projection 52 of another projection-type holding body 52 only needs to be screwed into the recess 54b in which the electrode-electrolyte assembly 42 is housed. Then, after a predetermined number of unit cells 50 are stacked, terminal plates 56 are screwed to both ends, whereby a stacked body of unit cells 50 is obtained.

Next, the lead wires 52h and 54h are connected. Normally, each cell 5 is set so that a high output voltage is obtained.
0 is connected in series. In the case of the polymer electrolyte fuel cell 40 illustrated in FIG. 1, the gas flow path 52e of the convex holding body 52
Through which the fuel gas flows, and the gas flow path 54e of the concave holding body 54
, So that air flows therethrough.
And the gas diffusion electrode 46 in contact with becomes an anode (-electrode),
The gas diffusion electrode 46 in contact with the concave holding member 54 serves as a cathode (+ pole).

That is, the unit cell 50 has (-+), (+
-), (-+) ..., the same poles are adjacent to each other. Therefore, in order to connect the cells 50 in series, for example, the upper terminal plate 56 is connected to the anode-side lead wire 52h of the cell 50 located at the uppermost position to form a negative electrode, and the lower terminal The plate 56 is connected to the cathode-side lead wire 54h of the unit cell 50 located at the lowermost portion to form a positive pole, and the unit cells 50 are connected in the order of (+-), (+-),. And the remaining lead wires 52h and 54h
Should be connected.

Finally, by attaching a fuel manifold (not shown) to the gas flow path 52g and attaching an air manifold (not shown) to the gas flow path 54g, the polymer electrolyte fuel cell 40 is completed.

When a fuel gas containing hydrogen such as a reformed gas and air are passed through the gas flow paths 52e and 54e of the polymer electrolyte fuel cell 40 having such a configuration, the fuel cell 40 is in contact with the projection 52b. Fuel is supplied to the gas diffusion electrode 46, and air is supplied to the gas diffusion electrode 46 in contact with the concave portion 54b. Thereby, each electrode / electrolyte joined body 42
The electrode reaction progresses in
It is taken out to the outside through 6, 56.

When a part of each unit cell 50 is connected in parallel, the connection order of the lead wires 52h and 54h may be changed, but the support frames 52a and 54a and the gas permeable member 52 may be connected.
A conductor may be used for a part of g and 54g, and a part of the same pole may be connected. In this case, the support frames 52a, 54
Since a and the gas permeable bodies 52h and 54h serve as lead wires, the lead wires 52h and 54h are unnecessary.

When disassembling the assembled fuel cell, the procedure may be reversed. Further, when only a part of the unit cells 50 are to be replaced, it is only necessary to remove only the holding bodies 52 and 54 constituting the unit cell 50 to be replaced.

Next, a polymer electrolyte fuel cell according to a second embodiment of the present invention will be described. FIG. 6 is an exploded sectional view of a polymer electrolyte fuel cell 60 according to the second embodiment of the present invention. In FIG. 6, a polymer electrolyte fuel cell 60 includes an electrode / electrolyte assembly 42 and a holding body 6 having a convex portion 62b on one surface and a concave portion 62d on the other surface.
2 is provided.

The polymer electrolyte fuel cell 60 has a structure in which the electrode / electrolyte joints 42 and the holding members 62 are alternately stacked in the stacking direction. Further, the convex portion 62b of the adjacent one of the holding members 62 and the concave portion 62d of the other holding member 62
And can be fastened and integrated by mechanical fastening means. The polymer electrolyte fuel cell 60 illustrated in FIG.
, Screwing means by screwing is used as mechanical fastening means.

The electrode / electrolyte assembly 42 is sandwiched between the tip of the projection 62b of one of the sandwiches 62 and the bottom of the recess 62d of the other sandwich 62.
The two sandwiching bodies 62, 62 and the electrode / electrolyte assembly 42 constitute one unit cell 50. In the polymer electrolyte fuel cell 60 illustrated in FIG.
Although 0 has a laminated structure of four layers, the same applies to a case where five or more unit cells are laminated.

The electrode / electrolyte assembly 42 has the same configuration as that shown in FIG. 2 and will not be described. Further, as shown in FIG. 7, the holding body 62 includes a support frame 62a.
And gas permeable members 62i and 62j.

An insulating layer 62c is provided on the convex portion 62b provided on one surface of the support frame 62a, and a part of the distal end surface, the outer surface, and the base surface of the convex portion 62b are covered with the insulating layer 62c. I have. This is because when the holding members 62 and 62 are screwed together, the insulation between the holding members 62 and 62 is ensured, and at the same time, the gas diffusion electrode 46 is brought into contact with the tip end surface of the convex portion 62b not covered by the insulating layer 62c. That's why. A male screw is provided on the outer peripheral surface of the insulating layer 62c.

A female screw which can be screwed with a male screw provided on the outer peripheral surface of the insulating layer 62c is provided on the inner peripheral surface of the concave portion 62d provided on the other surface of the support frame 62a.
The outer diameter of the recess 62d is slightly larger than the outer diameter of the electrode-electrolyte assembly 42,
2 can be accommodated in the recess 62d.

Further, when the two holding members 62, 62 are fastened, a space is formed between the bottom surface of the concave portion 62d and the front end surface of the convex portion 62b, and the height of the space is within the space. The height is slightly smaller than the height of the electrode / electrolyte assembly 42 so that a predetermined tightening pressure is applied to the sandwiched electrode / electrolyte assembly 42.

Two gas passages 62 penetrating in the radial direction and intersecting with each other are provided inside the support frame 62a.
e and 62f are provided so that fuel gas can flow through one of them and oxidant gas can flow through the other. Therefore, in the case of the present embodiment, the unit cells 50 are stacked such that different electrodes are adjacent to each other, such as (+-), (+-). Further, the holding body 62 also functions as a separator.

Further, on the side of the convex portion 62b of the support frame 62a, the gas permeable body burying hole 6 communicating with only the gas flow path 62e is provided.
2g is provided, and a gas permeable body embedding hole 62h communicating with only the gas flow path 62f is provided on the concave portion 62d side of the support frame 62a.

Here, a material having conductivity and corrosion resistance is used for the support frame 62a. Specifically, a preferable example is one in which a substrate made of stainless steel, Sn or Sn alloy, or stainless steel, copper, or the like is coated with Sn or Sn alloy.

The reason for requiring conductivity is that the gas diffusion electrodes 46, 46 of the electrode / electrolyte joints 42, 42 arranged at both ends of the holding body 62 are electrically connected, and the unit cells 50 are connected in series. That's why. Therefore, in the case of the holding body 62 shown in FIG. 7, unlike the holding bodies 52 and 54 shown in FIGS.
No leads are required.

Further, it is the support frame 6 that requires corrosion resistance.
2a is oxidized by being exposed to an oxidizing steam atmosphere,
This is because the passivation increases the contact resistance with the gas diffusion electrode 46 and lowers the power generation efficiency.

For the insulating layer 62c provided on the convex portion 62b of the support frame 62a, a material having heat resistance enough to maintain the insulating characteristics even at the operating temperature of the polymer electrolyte fuel cell 60 (around 80 ° C.) is used. . Specifically, polytetrafluoroethylene is a preferred example. Also,
The support frame 62a and the insulating layer 62c may be fixed using means such as screwing, bolting, and fitting.

The gas permeable members 62i and 62j have a cylindrical shape, and are buried in gas permeable member burying holes 62g and 62h provided in the support frame 62a, respectively. The gas permeable bodies 62i and 62j are provided with through holes 62k and 62l, respectively, penetrating in the gas flow paths 62e and 62f.

Here, for the gas permeable members 62i and 62j, a material having gas permeability and a strength that does not cause crush when the electrode electrolyte assembly 42 is sandwiched between the two sandwiching members 62, 62 is used. The gas permeability and strength are required for the same reason as the gas permeable bodies 52g and 54g used for the holding bodies 52 and 54 shown in FIGS.

However, in the case of the present embodiment, since the cells 50 are stacked in the order of (+ −), (+ −)..., The gas permeable members 62i and 62j do not need to be insulators.
A conductor may be used. Specifically, a ceramic porous body such as zirconia, a metal porous body, a laminate of a metal mesh, or the like can be used.

The gas permeable members 62i and 62j include:
The point that a porous body having no through holes 62k and 62l may be used, or a rib-like body made of a dense material may be used is that the gas permeable bodies 52g and 54 shown in FIGS.
Same as g.

Next, the polymer electrolyte fuel cell 6 shown in FIG.
The assembly procedure of No. 0 will be described. First, the concave portion 6 of one of the holding members 62 in which the gas permeable members 62i and 62j are embedded is provided.
The electrode / electrolyte assembly 42 is accommodated in 2d. Next, the convex portion 62b of the other holding member 62 in which the gas permeable members 62i and 62j are embedded is also replaced with the concave portion 62d of the one holding member 62.
And the protrusion 62b and the recess 62d may be screwed together.

Thus, the electrode-electrolyte assembly 42 is
A predetermined tightening pressure is uniformly applied by the tip end surface of the convex portion 62b and the bottom surface of the concave portion 62d. At this time, a portion of the tip end surface of the convex portion 62b of the one holding body 62, which is not covered with the insulating layer 62c, and one of the gas diffusion electrodes 46 of the electrode-electrolyte assembly 42 come into contact with each other, and The bottom surface of the concave portion 62d of the body 62 and the other gas diffusion electrode 46 of the electrode / electrolyte assembly 42 come into contact with each other to form one unit cell 50.

The same applies to the fastening operation of the second and subsequent unit cells 50. The electrode-electrolyte assembly 42 is housed in the recess 62d of the clamping body 62 already fastened, and the electrode-electrolyte assembly 4
The projection 62 of another holding body 62 is inserted into the recess 62d
It is only necessary to screw b.

Further, after a predetermined number of cells 50 are stacked, a fuel manifold (not shown) is finally attached to the gas passage 62e, and an air manifold (not shown) is attached to the gas passage 62f. Polymer fuel cell 6
0 is completed.

When a fuel gas containing hydrogen such as a reformed gas and an oxidizing gas containing oxygen such as air flow through the gas flow paths 62e and 62f of the polymer electrolyte fuel cell 60 having such a configuration, respectively. The fuel gas is supplied to the gas diffusion electrode 46 in contact with the convex portion 62b through the gas permeable body 62i to become an anode (negative pole), and the gas diffusion electrode 46 in contact with the concave portion 62d becomes the gas permeable member 62j. The air is supplied through the above to become a cathode (+ electrode). As a result, the electrode reaction proceeds in each electrode / electrolyte joined body 42, and the obtained electricity is transferred to the conductor sandwiching bodies 62, 62 disposed at both ends.
Is taken out to the outside.

When disassembling the assembled fuel cell, it is sufficient to carry out the procedure reverse to that described above. When only a part of the cells 50 is to be replaced, the structure of the cell 50 to be replaced It is similar to the first embodiment in that only the holding bodies 62, 62 need to be removed.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various modifications are possible without departing from the gist of the present invention. is there.

For example, in each of the above embodiments, the screwing means is used as the mechanical fastening means, but the outer surface of the convex portion provided on one holding member and the inner surface of the concave portion provided on the other holding member are used. By providing a projection on one of them and providing a groove for engaging the projection on the other, fitting the projection of one holding body into the recess of the other holding body, and simultaneously engaging the projection with the groove. Alternatively, adjacent holding bodies may be fastened to each other.

In the first embodiment, the electrode / electrolyte assembly is sandwiched by using a convex sandwiching body having convex portions on both sides and a concave sandwiching body having concave portions on both sides. However, it is also possible to use a holding body provided with a convex portion on one surface of the support frame and a concave portion on the other surface.

In the first embodiment, the ring-shaped lead wire is brought into contact with the electrode / electrolyte assembly. However, the tip of the convex portion 52b of the support frame and the concave portion 54b are formed.
A spiral groove may be provided on the bottom surface and on both end surfaces of the gas permeable bodies 52g and 54g, and a spiral lead wire may be embedded. Alternatively, instead of a lead wire, a thin layer conductor having gas permeability such as a metal mesh may be brought into contact with both surfaces of the electrode-electrolyte assembly to extract electricity generated through the thin layer conductor. good.

In the above embodiment, the structure in which only the unit cells are stacked has been described. However, a cooling plate may be arranged every time several cells are stacked. Further, in the above embodiment, the outer shape of the support frame is all cylindrical, but the outer shape of the support frame may be another shape such as a prismatic shape, whereby the same effect as in the above embodiment can be obtained. Can be.

[0089]

According to the fuel cell of the present invention, the electrode / electrolyte assembly is sandwiched by the sandwiching body having the gas flow path.
Since the clamps are fastened by mechanical fastening means, assembly is easier than conventional polymer electrolyte fuel cells in which several hundred cells are stacked and bolted together. Therefore, the number of steps can be reduced, and the manufacturing cost can be reduced.

Further, since the tightening work is performed for each electrode-electrolyte assembly, it is possible to tighten each electrode-electrolyte assembly at a uniform pressure, and there is an effect that the characteristic difference between the cells is reduced. .

Further, if an abnormality occurs in some of the cells after assembling the fuel cell, the fastening of the holding body at the site where the abnormality occurs is released, and only the electrode-electrolyte assembly in which the abnormality has occurred is released. Can be removed, so that maintenance work is facilitated.

As described above, the present invention makes it possible to manufacture a fuel cell having a small difference in characteristics between cells and easy to perform maintenance work at low cost. Therefore, if this is applied to, for example, a fuel cell system for an automobile, it contributes to an increase in the output of the automobile and a reduction in the cost, and this is an invention having an extremely large industrial effect.

[Brief description of the drawings]

FIG. 1 is an exploded sectional view of a polymer electrolyte fuel cell according to a first embodiment of the present invention.

FIG. 2 is a sectional view of an electrode-electrolyte assembly used in the polymer electrolyte fuel cell shown in FIG.

FIG. 3 (a) is a plan view of a convex holding body used in the polymer electrolyte fuel cell shown in FIG. 1, and FIG. 3 (b)
Is a sectional view taken along line AA ′.

FIG. 4 (a) is a plan view of a concave holding member used in the polymer electrolyte fuel cell shown in FIG. 1, and FIG. 4 (b)
Is a sectional view taken along line AA ′.

5 (a) is a plan view of a terminal plate used in the polymer electrolyte fuel cell shown in FIG. 1, and FIG. 5 (b)
It is the AA 'line sectional view.

FIG. 6 is an exploded cross-sectional view of a polymer electrolyte fuel cell according to a second embodiment of the present invention.

7 (a) is a plan view of a holding body used in the polymer electrolyte fuel cell shown in FIG. 6, and FIG. 7 (b)
FIG. 7 (c) is a sectional view taken along the line BB 'of FIG.

FIG. 8 is an exploded perspective view of a unit cell as a power generation unit of the polymer electrolyte fuel cell.

FIG. 9 is a perspective view showing a stack structure of a conventional fuel cell generally used.

[Explanation of symbols]

40, 60 solid polymer fuel cell 42 electrode-electrolyte assembly 44 solid polymer electrolyte membrane (electrolyte membrane) 46 gas diffusion electrode 50 unit cell 52 sandwiching body (convex holding body) 52e gas flow path 54 sandwiching body (concave type) Holder) 54e Gas flow path 62 Holder 62e, 62f Gas flow path

Claims (1)

[Claims] 1. An electrode / electrolyte assembly in which a pair of gas diffusion electrodes are joined to both surfaces of a solid polymer electrolyte, and a holding body which holds the electrode / electrolyte assembly and has a gas flow path constituting a cell And a mechanical fastening means for individually connecting the adjacent holding members to each other.