JP2002164075A - Solid polymer type fuel cell preventing electrolytic corrosion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell capable of preventing or reducing electrolytic corrosion. SOLUTION: The fuel cell is formed by sandwiching a fuel cell stack portion 30 between a flange and an insulator 4 having a connecting hole for gas or cooling water, the fuel cell stack portion comprising a plurality of separator 6 and generating elements (cells) 8. Mechanisms 12-1, 12-1, 22-1 and 22-2 for preventing corrosion (electrolytic corrosion) caused by a potential difference in fuel cell power generation cause extension of a creepage distance for insulation between the outermost part of the fuel cell stack portion and a conductive material on the outside of the fuel cell stack portion to reduce a corrosion current and to thereby prevent the electrolytic corrosion.

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 fuel cell using a material having a possibility of electrolytic corrosion and an electrolytic corrosion structure around the cell.

[0002]

2. Description of the Related Art A fuel cell is supplied with a fuel gas such as hydrogen and an oxidizing gas such as oxygen or air through a pipe, and electric power is generated through an electrochemical reaction between the fuel gas and the oxidizing gas. . At this time, water is also generated. Generally, in a polymer electrolyte fuel cell, generated water is discharged from the fuel cell by excess fuel gas and oxidant gas.

As shown in FIG. 7, a fuel cell stack 60
Is a power generator (single cell) 68 (68-1,..., 68-
(N-1)) and the separator 66 (66-1,..., 6)
6-n) are alternately stacked, and tightened with a pair of flanges 62-1 and 62-2 whose intervals are adjusted by bolts 71.

[0004] As shown in FIG. 8, the single cell 68 includes a reaction cell section 72, a sealing material 73, and a packing 75. A fuel gas supply groove 77 is formed at the center of one main surface of the separator 66, and an oxidizing gas supply groove (not shown) is formed at the center of the other main surface of the separator 66. A fuel gas supply passage 74a, a cooling water discharge passage 74b, and an oxidizing gas supply passage 74c are provided above the separator 66.
Are provided below the separator 66, and an oxidizing gas discharge passage 74d, a cooling water supply passage 74e, and a fuel gas discharge passage 74f are provided below the separator 66, respectively.

FIG. 9 is a conceptual sectional view of the fuel cell stack 2. The flange-shaped portion is called a flange only when it has a connection with the piping, and is called a terminal portion when it has no connection with the piping. In FIG. 9, the first flange 62-1 is arranged on the left side, and the right flange-shaped portion has a connection with the piping, and is referred to as a second flange here. If the right flange-shaped part does not have any connection with the pipe, this will be referred to as the terminating end.

In the sectional view of FIG. 9, the first flange 62-1 and the second flange 62-2 have an oxidizing gas supply port 82 having a predetermined diameter at an upper portion and a fuel gas outlet 84 at a lower portion. . In this example, the oxidizing gas is supplied to the first flange 62-
1, can be supplied from either of the second flange 62-2,
Fuel gas is also supplied to the first flange 62-1, the second flange 62-
2 can be discharged. In this cross section, the fuel gas supply port, the oxidant gas discharge port, the cooling water supply port, and the cooling water discharge port are not visible because they do not appear in the cross section.

As shown in FIG. 8, a fuel gas supply passage 74a for supplying a fuel gas and an oxidizing gas is provided inside the battery.
The oxidizing gas supply passage 74c is formed to have a predetermined diameter. Further, a fuel gas discharge path 74f and a oxidant gas discharge path 74d for discharging the remaining fuel gas and oxidant gas are formed to have a predetermined diameter. A supply path 74e and a discharge path 74b are also formed for the cooling water. The first insulator 64-1 and the second insulator 64-2 are also provided with connection holes for forming these channels.

As described above, the battery stack includes a plurality of conductive separators 66 (66-1,..., 6-n) and a plurality of power generators (single cells) 68 (68-1,. , 68-
(N-1)). Each single cell 68 is sandwiched between separators 66. Thus, a battery stack is formed. All power generators (single cells) 68 in the battery stack
Is supplied with fuel gas through a fuel gas supply path 74a, and oxidant gas is supplied through an oxidant gas supply path 74c. The remaining fuel gas and oxidant gas from all the power generators (single cells) 68 in the battery stack are discharged through a fuel gas discharge passage 74f and an oxidant gas discharge passage 74d. Water generated by the battery reaction is also discharged together with the remaining fuel gas and oxidizing gas.

The cooling water is supplied through a cooling water supply passage 74e, and is discharged through a cooling water discharge passage 74b through a cooling groove formed in the separator for every one separator or every few separators. The cooling water serves to cool the heat of reaction in the cell while passing through the cell stack, and to keep the fuel cell in the desired temperature range.

In a solid polymer fuel cell, the fuel gas and the oxidizing gas may be humidified, and the discharged fuel gas and the oxidizing gas contain generated water. When such moisture 90 adheres between the fuel cell stack and the conductive material outside the fuel cell stack, the electrolytic corrosion 50-1,
50-2 occurred.

[0011] Further, regarding the cooling water, since the cooling water is always in contact between the fuel cell laminated portion and the conductive material outside the fuel cell laminated portion, electrolytic corrosion occurs.

The principle of electrolytic corrosion will be described below with reference to FIG. In FIG. 5 (a), two metal plates are immersed in an electrolyte as electrodes, and they are connected to a battery. In this case, the metal plate connected to the + side of the battery functions as an anode, and the metal plate connected to the-side of the battery functions as a cathode. At the anode, electrons are removed from the metal in the metal plate,
The metal ionizes and dissolves or corrodes. Also,
In the cathode side metal plate, electrons are supplied excessively and are filled with electrons. As a result, the metal plate on the cathode side is corroded.

Next, as shown in FIG. 5B, the case where there are two electrolytes is considered. In this case, the corrosion side and the corrosion prevention side appear as a pair. That is, the metal plates B and D that accept electrons are on the corrosion-resistant side, and the metal plates A and C that emit electrons.
Is the corrosion side.

FIG. 6 shows a situation in an actual fuel cell stack 60. 6 corresponds to the dry cell portion in FIG. 5B. In FIG. 6, the insulator 64 (64-
1, 64-2), and water 90 bridging between the fuel cell stack and the flange 62 (62-1, 62-2) made of a conductive material is shown in FIG. 5 (b). Equivalent to beaker water. Pipe 92 schematically illustrated in FIG.
The electric path formed by (92-1, 92-2) is shown in FIG.
It corresponds to the conducting wire 81 of (b). When the bridge water 90 shown in FIG. 6 has conductivity, the relationship between the corrosion side and the corrosion prevention side shown in the example of FIG. 5B is based on the fuel cell stack and the flange 62 (62-1, 62-1) made of a conductive material. 62-2) occurs during
Electrolytic corrosion occurred in a material having low corrosion resistance.

In the case of the cooling water system, the cooling water corresponds to the beaker water in FIG.
The relationship between the corrosion side and the corrosion prevention side shown in the example of (b) occurred between the fuel cell stack portion and the flange 62, and the material having low corrosion resistance caused electrolytic corrosion.

It is generally said that in a solid polymer fuel cell, since the electrolyte membrane is a solid polymer, there is no scattering or consumption of the electrolyte, and the generated water or the like cannot have high conductivity. However, it has been clarified from the experiments of the present inventor that the electrolyte membrane component is decomposed and comes out of the cell in a small amount depending on the operating conditions.

In the solid polymer fuel cell, since the operating temperature is low, the humidified water contained in the supply gas and the water generated by the cell reaction are present not as water vapor but as a liquid, so that the bridge water is liable to be produced, and the electrolyte membrane component When even a small amount of water flowed out, the conductivity of the bridge water became very high, and electric corrosion occurred.

[0018]

As shown in FIG. 6, when the conditions for generating electrolytic corrosion are satisfied, the electrolytic corrosion is caused by the conductive material portion (for example, metal flange) connected to the outside of the fuel cell stack portion. And the pipe connected to the fuel cell)
Since a corrosive environment also occurs on the fuel cell stack portion side, when a metal is used for the separator or the like, electrolytic corrosion (50-2 in FIG. 9) occurs in the separator, and the fuel cell itself must be replaced. This is an essential problem of the fuel cell structure, and electric corrosion must be prevented even in consideration of economy and maintenance.

Accordingly, an object of the present invention is to realize a fuel cell structure capable of preventing or reducing electrolytic corrosion, and to provide a fuel cell having a longer life.

It is still another object of the present invention to provide a fuel cell which can prevent or reduce electric corrosion by a simpler mechanism.

Another object of the present invention is to provide a fuel cell capable of protecting the intended side of the inside of a cell or a cell connection portion by using an electric corrosion protection mechanism which has a paired relationship with electric corrosion. That is.

[0022]

Hereinafter, a description will be given of an anti-corrosion structure for achieving various aspects of the present invention.

FIG. 5 shows the following three methods for preventing electrolytic corrosion. That is, (1) lower the conductivity of the beaker water, (2) increase the electrode spacing, and (3) cut off the current path. In the example shown in FIG. 5, when the beaker water is pure water, almost no corrosion current is observed, and no electrolytic corrosion occurs. However, according to the research results of the inventor of the present application, bridge water corresponding to beaker water (water generated from a fuel cell, etc.)
Since it contains an electrolyte membrane component, it is currently impossible to make this part of water pure water, and it has been found that such a method of purifying water is a problem that must be separately considered. did.

When the conductivity of the portion corresponding to the beaker water, ie, the bridge water or the cooling water, cannot be reduced, as a countermeasure, the corrosion current flowing in the portion corresponding to the beaker water can be reduced by increasing the distance between the electrodes. The method of reducing (reducing corrosion) was effective. Further, as a method of interrupting the current path, it is more effective to use a method in which one end of the fuel cell is a terminal end having an insulating portion having no connection hole, and the pipe connection is established only from the other side of the fuel cell. It was a target.

In addition, it has also been found that the use of the fact that no electrolytic corrosion occurs on the negative side of the battery makes it possible to promote further corrosion protection.

The concept of the method will be described with reference to FIG. When the flange is made of a conductive material such as metal, the insulation distance L between the fuel cell stack and the conductive portion outside the fuel cell stack (see FIG. 5).
Is determined by the thickness of the insulator. If the pipe is made of a conductive material such as stainless steel even if the flange is not made of a conductive material, the insulation distance L between the fuel cell laminated portion and the conductive portion outside the fuel cell laminated portion can be reduced.
Is determined by the total thickness of the insulator and the flange.
At this time, assuming that the cross-sectional area of the water droplet or the cross-sectional area of the cooling water channel when bridge water is generated in the insulating portion is S, and the conductivity of the water is ρ, the electric resistance R of the water is calculated by a simple calculation method. R = L / (S * ρ), and the outermost potential of the fuel cell stack is V
s, the potential of the conductive flange or conductive pipe is V
When the relative relationship f is established, the electrolytic corrosion current I is given by I = (Vs−Vf) / R = (Vs−Vf) (S * ρ) /
L. Therefore, if L is set longer, the electrolytic corrosion current can be reduced accordingly, and the electrolytic corrosion can be prevented.

The length L can be increased by increasing the thickness of the insulator, increasing the thickness of the flange by using an insulating material, or integrating the insulator and the flange with an insulating material.

On the other hand, when the thickening of the insulator has a large effect on the stack size and the compactness is required, the conductive portion outside the fuel cell stack portion is formed in the flow path where the bridge water is generated or the cooling water flow path. By providing a mechanism for extending the insulation distance on the side, L can be lengthened.

When the length L is increased by providing a mechanism for extending the insulation distance, as shown in the conceptual diagram of FIG. 4B, the insulating property extending along the inside of the flow path where the bridge water occurs or the cooling water flow path is provided. The method of inserting the tube portion is simple. Depending on the shape of the flow path, the cross section of the insulating tubular portion may be not only circular but also square or rectangular, and a shape that is easy and reliable for installation and mounting can be selected.

The cylindrical portion may be formed integrally with the insulating portion, or may have a shape that can be divided. In the case where it can be divided, if the structure is such that water easily enters between the insulating portion and the insulating tubular portion, the insulating distance may not be as long as intended. As shown in FIG. 4C, the design insulation distance is L, but the actual insulation distance may be L ′ due to intrusion of water. Therefore, it is desirable that a material having a sealing property against water is provided between the insulating portion and the insulating tubular portion.

As described above, by lengthening L in this manner, it is possible to reduce and prevent electric corrosion. Further, one end of the fuel cell is a terminal end having an insulating portion without any connection hole, and the pipe connection is established only from the other side of the fuel cell. As a result, one of the two beakers shown in FIG. 5B does not exist, the current path can be cut off, and the cause of electrolytic corrosion can be eliminated.

Referring again to FIG. 5, no electrolytic corrosion occurs on the negative side of the battery. To take advantage of this phenomenon, one end of the fuel cell is again used as a terminal end having an insulating portion without any connection hole, and the pipe connection is established only from the other side of the fuel cell. This allows
One of the two beakers shown in FIG. 5B is no longer present. Since there is only one beaker, corrosion prevention is possible if the side to be electrically protected is installed on the side that is relatively negative potential (-) in fuel cell power generation. If two beakers remain, one of them is always on the corroded side, so that corrosion protection cannot be made only in the +-direction. Therefore, when a material having a possibility of electrolytic corrosion, particularly a metal material, is used in the fuel cell stack, the negative
The positive side is the first flange side, the positive potential of the fuel cell stack (+)
The fuel cell is installed on the side of the terminal end having the second insulating portion having no connection hole at all, and joined by the first flange and the terminal end via the first and second insulating portions. I do. As a result, the material having a possibility of being electrically corroded in the fuel cell stack portion is electrically corroded and does not corrode, and high durability is obtained.

Conversely, no material having the possibility of electrolytic corrosion is used in the fuel cell stack, no metal material is used, and the gas pipes to the outside of the fuel cell stack, ie, the fuel cell, are not used.
When a metal material is used for the cooling water pipe and the flange, the positive potential (+) side of the fuel cell stack is connected to the first flange, and the negative potential (-) side of the fuel cell stack is connected to the connection hole at all. The fuel cell is installed on the terminal end side having the second insulating portion not provided, and is joined by the first flange and the terminal end portion via the first and second insulating portions. As a result, the material having the possibility of electrolytic corrosion outside the fuel cell stack portion is electrically corroded and does not corrode, so that high durability can be obtained.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A fuel cell according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a sectional view of a fuel cell according to a first embodiment of the present invention. In FIG. 1, different cross sections are shown on the left and right sides. Here, the fuel cell has a first flange 2-1 as a conductive material and a second flange 2-2 as a conductive material, and has a first insulator 4-1 and a second insulator 4-1.
2. It comprises a battery stack 30.

In FIG. 1, an oxidizing gas supply port 10 having a predetermined diameter is provided between the first flange 2-1 and the second flange 2-2.
-1 is shown at the top, and the fuel gas outlet 10-2 is shown at the bottom. In the present embodiment, the oxidizing gas can be supplied from either the first flange 2-1 or the second flange 2-2, and the fuel gas is also supplied from the first flange 2-1 or the second flange 2-.
2 can be discharged. Further, the fuel gas supply port 24-1 is shown at the upper part, and the oxidant gas discharge port 24-2 is shown at the lower part. The fuel gas can be supplied from either the first flange 2-1 or the second flange 2-2, and the oxidizing gas can be discharged from either the first flange 2-1 or the second flange 2-2. ing.

Although not shown in the sectional view of FIG. 1, a cooling water supply port and a cooling water discharge port are provided. A fuel gas supply pipe (not shown) as a conductive material is connected to the fuel gas supply port 24-1 and the oxidant gas supply port 10-1.
Is connected to an oxidant gas supply pipe (not shown) as a conductive material. A fuel gas discharge pipe (not shown) as a conductive material is connected to the fuel gas discharge port 10-2, and an oxidant gas discharge pipe (a conductive material) as the conductive material is connected to the oxidant gas discharge port 24-2. (Not shown). Similarly, a cooling water supply pipe (not shown) is connected to a cooling water supply port (not shown), and a cooling water discharge port (not shown) is used to discharge cooling water as a conductive material. A pipe (not shown) is connected.

In FIG. 1, a connection hole 14-1 for connecting the oxidant gas supply port 10-1 and the oxidant gas supply path 16-1 to the first insulator 4-1 and a fuel gas discharge port 10-1 are provided. Connecting hole 14- for connecting the fuel cell 2 to the fuel gas discharge passage 16-2
2 is shown. Similarly, for the second insulator 4-2,
A connection hole 20-1 for connecting the fuel gas supply port 24-1 to the fuel gas supply path 18-1;
A connection hole 20-2 for connecting the oxidant gas discharge path 18-2 to the oxidant gas discharge path 18-2 is shown. Although not shown in the figure, connection holes for connecting the cooling water supply port and the cooling water supply path, and the cooling water discharge port and the cooling water discharge path are formed in the first and second insulators. Is provided. In this structure, gas and cooling water can be supplied and discharged from both sides of the first flange side and the second flange side, or from any direction.

The first insulator 4-1 has a sleeve 12 (12-1, 12-2) as a mechanism for preventing electric corrosion. The sleeve 12 extends from the first insulator 4-1 toward the outer end of the first flange 2-1. As shown in FIG. 2A, the inner diameter of the pipe 82 and the sleeve as the conductive material is made equal to the inner diameter of the oxidizing gas supply passage 16-1 to prevent an increase in pressure loss. Sleeve 12
May reach the outer end of the first flange 2-1 as shown in FIG. 1 or may extend halfway as shown in FIG. Further, as shown in FIG. 2B, the oxidizing gas supply pipe 83 as a conductive material may be extended to the inside to enhance the effect of preventing electrolytic corrosion. In these cases, as shown in FIGS. 2A and 2B, it is also important to rectify the flow by combining them so as not to cause unevenness on the flow path surface, thereby preventing pressure loss and corrosion. However, even when these unevenness preventing structures cannot be adopted from the viewpoint of workability and parts handling, the effect of preventing electrolytic corrosion can be expected.

The sleeve 12 may be manufactured integrally with the first insulator 4-1 as described above. However, as a separate insulating sleeve 94, and as shown in FIG. 2 (b), it is manufactured separately from the first insulator 4-1 and is coupled to the first insulator 4-1 at the time of assembly, and 12 may be configured.

The second insulator 4-2 is provided with a sleeve 22 (22-
1, 22-2).

In the present embodiment, as shown in FIG. 2A, the first insulator 4-1 having a concave portion around the connection hole 14-1 on the fuel cell stacking portion 30 side is used. The first insulator 4-1 is connected to the outermost separator 6-1 while preventing leakage of the oxidizing gas by the seal ring 30-2 provided in the recess.

Oxidant gas supply port 10-1 of first flange
Has a larger inner diameter than the oxidizing gas supply passage 16-1 at a portion corresponding to the sleeve 12-1, and this inner diameter is substantially equal to the outer shape of the sleeve 12-1 as an anti-corrosion mechanism.
The inner diameter of the oxidizing gas supply pipe 40 is
It is almost equal to the inner diameter of 2-1. Thereby, an increase in pressure loss in the sleeve structure can be prevented. The same applies to other sleeves, flanges, and insulators.

As shown in FIG. 2B, when a separately manufactured sleeve 94 is incorporated, the first flange 2-1 is used.
The one having a concave portion in the oxidant supply port 10-1 on the first insulator 4-1 side was used. A sleeve 94 having a sealing structure with the first insulating portion is incorporated into the recess, and the fuel cell laminated portion 30 and the first insulator 4-1 are sandwiched. Thereby, even when the sleeve 94 manufactured separately is used, sealing of the oxidizing gas and extension of the insulation distance can be achieved. The same applies to other sleeves, flanges, and insulators.

In the above example, the oxidizing gas supply port 1
The same is required for the fuel gas supply port 24-1, the fuel gas discharge port 10-2, and the oxidizing gas discharge port 24-2, and also for the cooling water supply port and the cooling water discharge port. Can be applied according to

Next, a fuel cell according to a second embodiment of the present invention will be described with reference to FIG. In the fuel cell of the second embodiment, the current path is first cut off, and then the fact that electrolytic corrosion does not occur on the negative potential side of the cell is used.

In this embodiment, a metal separator is used as the separator 6 (6-1,..., 6-n) constituting the fuel cell stack.

The connection between the fuel cell stack and the pipes is all present in the first flange 2-1. The oxidizing gas supply port 10-1 and the oxidizing gas supply path 16-1 are connected to the first insulator 4-1. Connection hole 14-1 for connecting the fuel gas outlet 10
-2 and a connection hole 14-2 for connecting the fuel gas discharge path 16-2, and a connection hole for connecting a fuel gas supply port (not shown) and a fuel gas supply path (not shown) (FIG. Not shown)
And a connection hole (not shown) for connecting an oxidizing gas discharge port (not shown) and an oxidizing gas discharge path (not shown). Further, a connection hole (not shown) for connecting a cooling water supply port (not shown) and a cooling water supply path (not shown), a cooling water discharge port (not shown), and a cooling water discharge path (not shown). A connection hole (not shown) is formed for connection to the device.

On the other hand, the end portion 32 corresponding to the second flange
-2 is not provided with a gas or cooling water supply port or discharge port, and the second insulator 34-2 has no connection hole. Here, since there is no connection hole in the second insulator 34-2, there is no place where bridge water or cooling water equivalent to beaker water which causes corrosion is accumulated, and a structure in which most of the electric corrosion current path is cut off. Therefore, electrolytic corrosion is greatly reduced.

However, as described above, the first flange 2
-1 are connected to the pipes, and the first insulator 4-1 has connection holes 14 (14-1, 14-2).
In (b), the bridge water and the connection port corresponding to the left beaker water remain. Therefore, the first part
The sleeve structure described in the embodiment is adopted.

Also, as shown in FIG. 5, in order to make use of the fact that electrolytic corrosion does not occur on the negative potential side, the negative potential (-) side of the fuel cell stacking section 30 is installed on the first flange side to achieve stacking. Was. From this, the outermost part of the fuel cell stack 30 in contact with the first insulator 4-1 on the first flange 2-1 side and the first
The potential relationship with the flange 2-1 is such that the outermost portion of the fuel cell stack has a negative potential (-) and the first flange 2-1 has a positive potential (+). In the present embodiment, since the metal separator 6 is used, the connection hole 14 (14-
The presence of bridge water or cooling water in 1,14-2) causes electric corrosion, which may cause electric corrosion of the metal separator. However, the potential relationship is defined as the outermost part of the battery stack = negative potential (-),
Since the first flange is set to the positive potential (+), the separator 6 is protected from corrosion and is kept in a completely sound state.

As described above, the metal separator is used in the second embodiment. However, when a commonly used carbon separator is used, the carbon separator is rich in corrosion resistance, and it is necessary to protect the fuel cell stack portion from corrosion. There is no. Conversely, if an aluminum alloy is used for the first flange 2-1 or a metal is used outside the fuel cell stack, it is desirable to protect the metal portion from corrosion. Therefore, in such a case, the positive potential (+) side of the fuel cell stack is disposed on the first flange side to achieve stacking, and the fuel cell stack is in contact with the first insulator 4-1 on the first flange side. The potential relationship between the outermost part and the first flange 2-1 is set such that the outermost part of the fuel cell stack 30 has a positive potential (+) and the first flange 2-1 has a negative potential (-).

[0053]

As described above, according to the fuel cell of the present invention, electric corrosion can be prevented or reduced, and a longer life can be achieved.

Further, electric corrosion can be prevented or reduced by a simple mechanism. Therefore, a long-life fuel cell can be obtained without impairing workability and without increasing costs.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration of a fuel cell according to a first embodiment of the present invention.

FIG. 2 is a partial cross-sectional view showing an electric corrosion preventing mechanism in the fuel cell according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating a configuration of a fuel cell according to a second embodiment of the present invention.

FIG. 4 is a view for explaining a method for preventing electrolytic corrosion according to the present invention.

FIG. 5 is a diagram illustrating the principle of electrolytic corrosion.

FIG. 6 is a diagram for explaining the reason why electric corrosion occurs in a conventional fuel cell.

FIG. 7 is a perspective view showing an assembled conventional fuel cell stack.

FIG. 8 is a fuel cell stack 30 of a conventional fuel cell.
FIG. 3 is an exploded perspective view of FIG.

FIG. 9 is a diagram illustrating an example of electrolytic corrosion of a conventional fuel cell.

[Explanation of symbols]

2-1: First conductive flange 2-2: Second conductive flange 4-1: First insulator 4-2: Second insulator 6 (6-1, 6-2,..., 6-n): Separator 8 (8-1, 8-2,..., 8- (n-1)): Power generator, single cell 10-1: Oxidant gas supply port 10-2: Fuel gas exhaust Outlet 12-1: Oxidant gas supply port sleeve 12-2: Fuel gas outlet port sleeve 14-1: Oxidant gas supply connection hole 14-2: Fuel gas discharge connection hole 16-1: Oxidant gas supply path 16-2: fuel gas discharge path 18-1: fuel gas supply path 18-2: oxidant gas discharge path 20-1: fuel gas supply connection hole 20-2: oxidant gas discharge connection hole 22-1: fuel gas Supply port sleeve 22-2: Oxidant gas discharge port sleeve 24-1: Fuel gas supply port 24-2: Oxidant gas Outlet 30: Fuel cell stack 32-2: Second flange (end) 34-2: Second insulator (end) 40: Oxidant gas supply pipe 50-1: Electrocorrosion generated outside fuel cell stack 50-2: Corrosion portion generated in fuel cell laminated portion 60: Stack 62-1: First flange 62-2: Second flange 64-1: First insulator 64-2: Second insulator 66: Separator 68: power generator (single cell) 71: bolt 72: reaction cell part 73: seal part 74 (a): fuel gas supply path 74 (b): cooling water discharge path 74 (c): oxidant gas supply path 74 ( d): Oxidant gas discharge path 74 (e): Cooling water supply path 74 (f): Fuel gas discharge path 75: Packing, packing 77: Fuel cell gas supply groove 81: Conductor 82, 83: Pipe 94: Separated Sleeve 90: Moisture 92-1,9 2-2: Piping, etc.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Nagao Nagao 1-1, Akunouramachi, Nagasaki City, Nagasaki Prefecture Mitsubishi Heavy Industries, Ltd. Nagasaki Shipyard F-term (reference) 5H026 AA06 CC03 CC06 CC08 CX10 EE02 HH03 5H027 AA06 CC06

Claims (12)

[Claims] A fuel cell stack comprising a fuel cell stack formed by alternately stacking separators and single cells as a power generator, and a conductive member to which a power generation potential is applied by being in contact therewith without insulation. In order to prevent electric corrosion, which is corrosion caused by a potential difference caused by power generation in the fuel cell stack, the insulation distance in the fluid path between the fuel cell stack and the conductive material outside the fuel cell stack is extended. A polymer electrolyte fuel cell having a prevention mechanism. 2. The fuel cell according to claim 1, wherein a fuel gas supply port and an oxidant gas supply port are respectively connected to a fuel gas and an oxidant gas supply pipe, and the fuel gas and the oxidant gas are discharged. The fuel gas outlet and the oxidizing gas outlet connected to the pipes respectively.
A first flange having at least one, a first insulating portion provided inside the first flange, and having a connection hole communicating with one of the gas supply ports or the gas discharge ports; Fuel gas supply port and oxidant gas supply port connected to fuel gas and oxidant gas supply pipes respectively, and fuel gas discharge port and oxidant gas discharge port connected to fuel gas and oxidant gas discharge pipes respectively A second flange having at least one of the four connection ports; and a connection hole provided inside the second flange and communicating with one of the gas supply ports or the gas discharge ports. A second insulating portion, a fuel cell laminated portion joined by the first flange and the second flange via the first and second insulating portions, and the first or second insulating portion. Gas supply port Is provided in at least one of the connection holes leading to the gas discharge port, and extends the insulation distance in the gas flow path between the conductive material outside the fuel cell stack and the outermost part of the fuel cell stack. A fuel cell comprising: a mechanism. 3. The fuel cell according to claim 1, further comprising a fuel gas supply port and an oxidant gas supply port connected to the fuel gas supply pipe and the oxidant gas supply pipe, respectively. A first and / or a fuel gas outlet and / or an oxidant gas outlet respectively connected to the fuel gas discharge pipe and the oxidant gas discharge pipe.
And a fuel gas connection hole and an oxidant gas connection hole, which are provided inside the first flange and communicate with the fuel gas supply port and the oxidant gas supply port, respectively. If there is a fuel gas outlet or an oxidizing gas outlet provided by the above, a first insulating part also having a connection port communicating with each of the discharge ports, and a second insulating part having no connection port at all. A fuel cell stack unit joined by the first flange and the terminal unit via the first and second insulating units; and a gas supply port or gas of the first insulating unit. An anti-corrosion mechanism that is provided in at least one of the connection holes that communicates with the discharge port and that extends the insulation distance in the gas flow path between the conductive material outside the fuel cell stack and the outermost part of the fuel cell stack; A fuel cell comprising: 4. The fuel cell according to claim 1, further comprising: a first flange having a cooling water supply port connected to a cooling water supply pipe; and a cooling water supply provided inside the first flange. A first insulating portion having a connection hole communicating with a mouth, a second flange having a cooling water discharge port connected to a cooling water discharge pipe, and a cooling water drain provided inside the second flange. A second insulating portion having a connection hole communicating with an outlet; a fuel cell stack portion joined by the first flange and the second flange via the first and second insulating portions; A connection hole communicating with a cooling water supply port or a cooling water discharge port of the first or second insulating section, provided between at least one of the connection holes and the conductive material outside the fuel cell stack section and the outermost portion of the fuel cell stack section; The insulation distance in the cooling water flow path Fuel cell comprising the electrolytic corrosion preventing mechanism. 5. The fuel cell according to claim 1, wherein the first flange has a cooling water supply port connected to the cooling water supply pipe and a cooling water discharge port connected to the cooling water discharge pipe. A first insulating portion provided inside the first flange and having a connection hole communicating with the cooling water supply port and a connection hole communicating with the cooling water discharge port, and a second insulation having no connection port at all. A fuel cell stack unit joined by the first flange and the terminal unit via the first and second insulating units; a cooling water supply port of the first insulating unit Alternatively, the electrolytic corrosion is provided in at least one of the connection holes communicating with the cooling water discharge port and extends the insulation distance in the cooling water flow path between the conductive material outside the fuel cell stack and the outermost portion of the fuel cell stack. And a prevention mechanism. 6. The fuel cell according to claim 3, wherein a material having a possibility of electrolytic corrosion is used in the fuel cell stack, in particular, a metal material is used, and the negative potential (-) side of the fuel cell stack is set to a negative potential. On one flange side,
The positive potential (+) side of the fuel cell stack is installed on the terminal side having the second insulating part having no connection hole, and the first and second insulating parts are provided by the first flange and the terminal part. Fuel cell that is joined through. 7. The fuel cell according to claim 1, wherein a material having a possibility of electrolytic corrosion is not used in the fuel cell stack, and particularly, no metal material is used. The material with the possibility of electric corrosion, especially the metal material, is used for the gas pipe, the cooling water pipe and the flange to the battery, and the positive potential (+) side of the fuel cell stack part is on the first flange side.
The negative potential (-) side of the fuel cell stack is installed on the terminal end side having the second insulating part having no connection hole, and the first and second insulating parts are connected by the first flange and the terminal part. Fuel cell that is joined through. 8. The fuel cell according to claim 2, wherein the electrolytic corrosion preventing mechanism extends along an inner surface of the fluid flow path from an insulating portion provided inside the flange toward an outer end of the flange. A fuel cell comprising an extending insulating cylinder. 9. The fuel cell according to claim 8, wherein the insulating tubular portion is formed integrally with an insulating portion provided inside the flange. 10. The fuel cell according to claim 8, wherein the insulating tubular portion is provided with an insulating portion provided inside the flange.
A fuel cell formed of something that is separable. 11. The fuel cell according to claim 10, wherein the insulating portion provided inside the flange and the insulating tubular portion which can be separated have a sealing structure between the insulating portion provided inside the flange. . 12. The fuel cell according to claim 2, wherein the flange and the insulator are integrated and made of a non-conductive material.