JP3111573B2 - Molten carbonate fuel cell separator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a separator used as a partition plate of a molten carbonate fuel cell, among fuel cells used in the energy sector for directly converting chemical energy of fuel into electric energy.

[0002]

2. Description of the Related Art Molten carbonate fuel cells use a tile (electrolyte plate) in which molten carbonate is impregnated with a porous material as an electrolyte, and use both sides of a cathode (oxygen electrode) and an anode (fuel electrode) from both sides. A cell in which an oxidizing gas is supplied to the cathode side and a fuel gas is supplied to the anode side so that power is generated by a reaction between the cathode side and the anode side is defined as one cell, and each cell is multilayered through a separator. To form a stack.

[0003] Various types of separators have been conventionally proposed as the separator used as a partition plate when stacking the cells of the fuel cell, but press-molded separators have recently been proposed due to ease of production. I have.

FIGS. 8 and 9 show an example of a conventional separator manufactured by press molding and used for an internal manifold type fuel cell. That is, the conventional separator 1 is composed of the center plate 2
And an anode-side mask plate 3a and a cathode-side mask plate 3b, which are cut out of the central portion and are located only on the peripheral portion and are located on both sides of the peripheral portion of the center plate 2, and overlap the peripheral portion. In order to place the corrugated plates 4 and 5 between the center plate 2 and the two mask plates 3a and 3b, and to support the anode 6 and the cathode 7 on both sides of the center portion of the center plate 2 Corrugated plates 4 and 5 are arranged, and among the peripheral manifolds, a center plate for supplying and discharging the oxidizing gas OG to and from the cathode 7 (the supply manifold 8 is shown in the figure) is a center plate as shown in FIG. 2 is bent to make contact with the anode-side mask plate 3a, and the fuel gas F In the supply / discharge manifold (not shown, the supply manifold 9 is shown), as shown in FIG. 9, the peripheral portion of the center plate 2 is bent to abut the cathode side mask plate 3b, and the center plate 2 in the manifolds 8 and 9 is bent. And anode side mask plate 3a
Also, the joint A of the cathode side mask plate 3b and the joint B of the periphery of the center plate 2 and the joints B of the two mask plates 3a, 3b are welded (seam welded) to be integrally joined. 10 is a tile.

In the conventional separator 1 shown in FIGS. 8 and 9, the oxidizing gas OG is supplied from the manifold 8 to the cathode 7 through a gas passage formed by the corrugated plate 5, while the fuel gas FG is The gas is supplied from the manifold 9 to the anode 6 through a gas passage formed by the corrugated plate 4, and is sealed at the peripheral portion and the manifold portion by a wet seal portion between the mask plates 3 a and 3 b and the tile 1. is there.

[0006]

However, in the above-mentioned conventional separator 1, the mask plates 3a and 3b formed by cutting out the central portion and press-molding the manifolds 8 and 9 are provided.
The center plate 2 is formed by press-forming the parts, and the mask plates 3a and 3b and the center plate 2 are welded at the joints A and B. , And the electrodes of the anode 6 and the cathode 7 are placed inside the mask plates 3a and 3b. Therefore, the mask plates 3a and 3b have a large area as compared with the size of the electrodes. Also, the mask plate is expensive in material and processing costs and wasteful as a battery. Since both the mask plates 3a and 3b and the center plate 2 are press-formed, the mask plates 3a and 3b and the center plate 2 are assembled. Sometimes rigid and inflexible. Therefore, when the electrode becomes thin due to creep or sintering during operation of the fuel cell, the gap between the electrode and the electrode becomes large, the contact with the electrode becomes poor, the electric resistance increases, and the cell performance decreases. The center plate 2 and the mask plates 3a and 3b are connected to a peripheral joint B and a joint A of the manifolds 8 and 9.
It is necessary to perform the final surface treatment because it is welded, but there is a gap on the peripheral side due to welding, so there is a disadvantage that it is poor in soundness and easy to corrode. And the number of processing steps increases.

Accordingly, the present invention has been made to increase the effective area by increasing the size of the electrode, to eliminate the welded portion, to be able to follow the reduction in thickness due to creep and sintering of the electrode, and to reduce the thickness on the anode side. It is intended to improve the sealing performance by wet sealing.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a method for forming a wet seal surface on the periphery of a single separator body by bending the periphery to one side and projecting to the side. The supply / discharge manifold for the oxidizing gas and the fuel gas is provided, and the separator body in the portion of the supply / discharge manifold for the oxidizing gas is bent in the same direction as the bending direction of the periphery to form a wet seal surface around the manifold. At the same time, the separator body of the fuel gas supply / discharge manifold portion is bent in a direction opposite to the bending direction of the periphery to form a wet seal surface around the manifold, and both upper and lower end edges are bent outward to vertically. Direction, and the bent part is in contact with the back surface of the wet seal surface around the separator body by metal touch. A cathode rail formed into a cylindrical shape in accordance with the shape of the separator body is disposed around the separator body, and the bent portion of the cathode rail is brought into contact with the back surface of the wet seal surface around the separator body. In this case, a gas passage is formed on both surfaces of the separator body, and a manifold for supplying the fuel gas is provided. A hole is formed in the side wall of the cathode rail located on the side to communicate with the gas passage of the oxidizing gas formed on one side of the separator body, so that the oxidizing gas can be supplied from the outer periphery of the stack to the gas passage of the oxidizing gas through the hole. Configuration.

Alternatively, a gas supply manifold around the separator main body may be replaced with a manifold through which fuel gas flows by making a hole in a cathode rail around the gas supply side.

[0010] An oxidizing gas discharge manifold may be provided at the center of the separator body so that the oxidizing gas is supplied from a hole in the cathode rail facing the periphery.

Further, the manifold of the separator body may be used only for supplying and discharging fuel gas, and the supply and discharge of oxidizing gas may be performed through a hole provided in the cathode rail.

[0012]

When a cell in which a tile is sandwiched between both electrodes of a cathode and an anode from both sides is laminated via the separator of the present invention, on the anode side, the peripheral sealing surface and the sealing surface of the manifold portion come into contact with the tile and become wet. It becomes a seal part, and on the cathode side, the cathode rail and the tile have a metal touch. Anode and cathode electrodes can be placed around the separator body and at locations other than the manifold and cathode rails, so that the electrode area can be increased and the effective area can be increased. By eliminating the oxidizing gas supply manifold or the oxidizing gas supply manifold and the exhaust manifold, the electrode effective area can be further increased. Since there is no welding point, there is no danger of creating a gap at the joint,
No final surface treatment is required for the welded portion, and the processing steps can be simplified.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 3 show an embodiment of the present invention, which has a manifold 12 for supplying an oxidizing gas OG and a manifold 13 for supplying a fuel gas FG on one side of a peripheral portion, and on the other side. A tile 1 provided with a manifold 14 for discharging oxidizing gas OG and a manifold 15 for discharging fuel gas FG
In accordance with 1, the plate is press-formed to bend the periphery upward, and then bent outward in the horizontal direction to form a wet seal surface C, and to the supply / discharge manifolds 12 and 14 for the oxidizing gas OG. At the corresponding position, the wet sealing surface D and the manifolds 12 and 14 are formed by bending upward on the anode side, and the fuel gas F
At positions corresponding to the G supply / discharge manifolds 13 and 15, the separator body 16 having the wet seal surface E and the manifolds 13 and 15 formed by bending downward on the cathode side so as to be manufactured. As shown in FIGS. 2 and 3, both upper and lower ends are bent outwardly around the separator body 16 so that the separator body 16 has flexibility in the vertical direction.
Cathode rail 1 formed in a cylindrical shape according to the shape of
7, the bent portion at the upper end of the cathode rail 17 is brought into contact with the back surface of the wet seal surface C around the separator body 16 by metal touch, and the bent portions of the manifolds 12, 13, 14, 15 are Distributors 18 and 19 for flowing gas are respectively fitted and arranged, and further, corrugated plates 20 and 21 for forming gas passages are arranged on both front and back surfaces of the separator body 16 to constitute the separator of the present invention.

When a cell having the anode 22 and the cathode 23 superposed on both surfaces of the tile 11 is partitioned by the separator of the present invention and laminated, a wet seal surface C around the separator body 16 and a manifold portion are formed. The wet sealing surfaces D and E are brought into contact with the tile 11 and the lower surface of the bent portion at the lower end of the cathode rail 17 is brought into contact with the tile 11, and between the other portions of the tile 11 and the corrugated plates 20, 21. Is the anode 2
2 and the cathode 23 are sandwiched and pressed against the tile 11 by a separator to be supported. for that reason,
As shown in FIG. 3, the anode 22 and the cathode 23 are defined as outer dimensions having a size reaching the peripheral portion of the tile 11.
The supply / discharge manifolds 12, 14, and 13, for the oxidizing gas OG and the fuel gas FG on one side and the other side of the peripheral portion.
The manifold 1 having a diameter sufficient to fit the convex portions forming the wet sealing surfaces D and E of the separator body 16 and the distributors 18 and 19 at the position corresponding to 15.
2, 13, 14, 15 are provided, and the electrode area is increased so that the electrode effective area can be increased.

Further, the distributors 18 and 19
Are provided with large-diameter orifices 18a and 19a so that a large amount of gas can easily flow in the peripheral direction, and a small amount of gas necessary for the reaction inside the distributors 18 and 19 is provided inside the orifices 18a and 19a. Small diameter orifice 18
b and 19b are provided.

As shown in FIG. 2, when the cells are stacked with the separator of the present invention interposed therebetween, on the anode 22 side, the wet seal surface C around the separator body 16 and the wet seal surface D protruding toward the anode 26 contact the tile 11. As a result, the fuel gas supplied to the anode 22 side can be prevented from leaking.
On the other hand, on the cathode 23 side, the wet seal surface E protruding to the cathode 27 side comes into contact with the tile 11 to perform wet sealing. However, since the cathode rail 17 and the tile 11 have a metal touch, there is some gas leak. Since the cathode side has a large amount of gas, a slight gas leak does not matter.

Now, the oxidizing gas OG is supplied to the supply manifold 1.
2, the oxidizing gas O as shown in FIG.
G is the orifice 18a, 18 of the distributor 18
b, flows through the gas passage formed by the corrugated plate 21 and is supplied to the cathode 23 side. At this time, the oxidizing gas O
G easily flows in the direction of the discharge manifold 14, so that it hardly flows to the peripheral portion. However, the distributor 18 increases the diameter of the orifice 18a toward the periphery so that a large amount of gas can easily flow. Therefore, after a large amount of the oxidizing gas OG flows to the peripheral portion of the cathode 23, the oxidizing gas OG flows in the direction of the central portion, resulting in a uniform flow.

On the other hand, when the fuel gas FG is guided to the supply manifold 13, it is supplied to the anode 22 through the orifices 19a and 19b of the distributor 19 as shown in FIG. In this case, too, a large amount of fuel gas FG flows easily in the peripheral direction.
Will be uniformly flowed over the entire area.

When the oxidizing gas OG is supplied to the cathode 23 and the fuel gas FG is supplied to the anode 22, reactions occur on the cathode 23 and the anode 22, respectively. Since the areas of the cathode 23 and the anode 22 can be increased to the position of the conventional mask plate, the area of the battery reaction is increased, and the effective area is accordingly increased.

When the battery is used, the electrodes of the cathode 23 and the anode 22 become thinner due to creep and sintering, and the pressing of the separator against the tile 11 becomes insufficient and the battery performance deteriorates.
7 has flexibility, the cathode rail 17 bends due to the tightening force of the battery, so that it can follow the thickness decrease due to the creep of the electrode, and the electrode can always be pressed against the tile 11 with a constant pressing force. It becomes possible.

In the above embodiment, the cathode 23 and the anode 22 are directly pressed against the tile 11 by the corrugated plates 20 and 21. However, the electrodes are not pressed between the electrodes and the corrugated plates 20 and 21. Needless to say, a punching metal may be interposed in the separator body 16 without using the corrugated plates 20 and 21.
May be directly provided with irregularities.

FIG. 4 shows another embodiment of the present invention, in which a hole 24 for passing an oxidizing gas OG is provided in the cathode rail 17 so that the container itself containing the stack functions as a header. This makes it possible to supply an oxidizing gas from the outer periphery of the stack.

FIG. 5 shows a configuration in which the cathode rail 17 of FIG. 4 is used on one side serving as a supply side of the oxidizing gas OG, and the manifold 12 for supplying the oxidizing gas OG is eliminated.
Is supplied directly to the cathode 23 side through the hole 24 of the cathode rail 17 by directly supplying to the container containing the stack.

In the embodiment of FIG. 5, since the oxidizing gas can be positively taken in from the outside through the hole 24 of the cathode rail 17, the internal manifold for supplying the oxidizing gas can be eliminated, and the cathode 23 can be located at that location. As a result, the area of the electrode can be further increased.

FIG. 6 shows still another embodiment of the present invention. Opposite cathode rails on the supply side and discharge side of the oxidizing gas OG are connected to the cathode rail 17 having holes 24 as shown in FIG. Thus, the oxidizing gas OG supplied to the periphery of the stack can be supplied from opposite sides, and the oxidizing gas discharge manifold 14 is provided at the center of the battery.

In the embodiment shown in FIG. 6, the fuel gas FG flows in one direction from the supply side to the discharge side, while the oxidizing gas OG can partially flow counter to the fuel gas FG with the separator interposed therebetween. .

Further, FIG. 7 shows a cathode rail 17 having a hole 24 on the side where the supply manifold 12 for supplying the oxidizing gas OG is provided and the side where the discharge manifold 14 is provided, as in FIG. An external manifold is provided with the other side being the discharge side, and the oxidizing gas discharge manifold 14 is also eliminated inside the battery. In this case, by dividing the container into the oxidizing gas inlet side and the oxidizing gas outlet side, the oxidizing gas can be supplied to one side of the stack and discharged from the other side.

According to the embodiment of FIG. 7, there is an effect that the area of the electrode can be further increased.

In the embodiment shown in FIGS. 5 to 7, the oxidizing gas O is passed through the hole 24 of the cathode rail 17.
When supplying or discharging G, the cathode rail 17
There is some gas leakage because the contact between the metal and the tile 11 is a metal touch. However, since a large amount of gas is supplied to the cathode 23, some leakage does not hinder.

[0031]

As described above, according to the separator for a molten carbonate fuel cell of the present invention, a single separator body having a wet seal surface formed by bending the periphery to one side and further projecting to the side. A manifold for supplying and discharging the oxidizing gas and the fuel gas is provided in a peripheral portion of the manifold, and the separator body in a portion of the manifold for supplying and discharging the oxidizing gas is bent in the same direction as the bending direction of the periphery to wet seal around the manifold. The separator body of the fuel gas supply / discharge manifold portion is bent in a direction opposite to the bending direction of the periphery to form a wet seal surface around the manifold, and the upper and lower edges are outwardly formed. To give flexibility in the up and down direction and the bent portion is the back surface of the wet seal surface around the separator body A cathode rail formed into a cylindrical shape in accordance with the shape of the separator body so as to contact with the touch of the separator is disposed around the periphery of the separator body. The contact is made to seal the oxidizing gas, and furthermore, a distributor is arranged in the manifold portion, and a gas passage is formed on both surfaces of the separator body, and further, the fuel gas supply manifold is provided. A hole is formed in the side wall of the cathode rail located on the side provided with the gas passage for the oxidizing gas formed on one surface of the separator body, and the oxidizing gas can be supplied from the outer periphery of the stack to the gas passage for the oxidizing gas through the hole. With such a configuration, the following excellent effects can be obtained. (i) Compared to a conventional mask plate in which the electrodes are arranged inside, the electrodes can be positioned as far as the conventional mask plate, the area of the electrodes can be increased, and the size of the battery can be reduced. The ratio of the occupied electrodes can be increased, and the effective area can be increased. (ii) Since welding conventionally required is eliminated, it is possible to avoid a situation in which soundness is impaired due to generation of a gap due to welding, and a situation in which the number of processing steps is increased due to surface treatment. (iii) Especially on the anode side where sufficient sealing is required, since the wet sealing surface formed by the separator body comes into contact with the tile and is wet-sealed, there is no problem of fuel gas leakage. (iv) The thickness of the electrode caused by creep during use is reduced by the flexibility of the cathode rail,
Since the contact of the electrodes with the tiles does not get worse,
There is no possibility that battery performance will be reduced. (v) Eliminate manifolds for supply or supply and discharge of oxidizing gas to the cathode, and make holes in the cathode rails and use containers with built-in stacks as oxidizing gas headers to increase the electrode area. As a result, the effective area of the electrode can be increased.

[Brief description of the drawings]

FIG. 1 is a plan view showing one embodiment of a separator for a molten carbonate fuel cell according to the present invention.

FIG. 2 shows a cross section of the separator for a molten carbonate fuel cell of the present invention, where (A) is an enlarged view taken along the line II-A-II-A of FIG. 1 and (B) is an enlarged view of FIG. FIG. 2 is an enlarged view taken in the direction of arrows II-II-II-II.

FIG. 3 is an exploded perspective view of the molten carbonate fuel cell separator of the present invention.

FIG. 4 is a sectional view showing another example of the cathode rail according to the present invention.

FIG. 5 is a plan view showing another embodiment of the separator for a molten carbonate fuel cell according to the present invention.

FIG. 6 is a plan view of a modified example of FIG. 5;

FIG. 7 is a plan view showing still another embodiment.

FIG. 8 is a sectional view of a conventional separator showing a section of a manifold for supplying an oxidizing gas to a cathode.

FIG. 9 is a cross-sectional view of a conventional separator showing a cross-section of a manifold for supplying fuel gas to an anode.

[Explanation of symbols]

 Reference Signs List 11 tile 12 oxidizing gas supply manifold 13 fuel gas supply manifold 14 oxidizing gas discharge manifold 15 fuel gas discharge manifold 16 separator body 17 cathode rail 18, 19 distributor 20, 21, corrugated plate 22 anode 23 cathode 24 hole C, D , E Wet seal surface OG Oxidizing gas FG Fuel gas

Claims (4)

(57) [Claims] 1. A manifold for supplying and discharging oxidizing gas and fuel gas is provided at a peripheral portion of a single separator body formed by bending the periphery to one side and further projecting to the side to form a wet seal surface. The separator body of the oxidizing gas supply / discharge manifold portion is bent in the same direction as the peripheral bending direction to form a wet seal surface around the manifold, and the fuel gas supply / discharge manifold portion of the separator body is removed. , Bending in the opposite direction to the bending direction of the periphery to form a wet seal surface around the manifold, and bending the upper and lower edges outward to have flexibility in the vertical direction, and the bent portion is formed around the separator body. Shaped into a cylinder according to the shape of the separator body so that it comes in contact with the back surface of the wet seal surface with metal touch The cathode rail thus formed is arranged in the peripheral portion of the separator body, and the bent portion of the cathode rail is brought into contact with the back surface of the wet seal surface around the separator body to seal the oxidizing gas, and further, the manifold A separator for a molten carbonate fuel cell, wherein a distributor is disposed in a portion and gas passages are formed on both surfaces of the separator body. 2. A fuel gas supply / discharge manifold and an oxidant gas discharge manifold are provided around one separator body having a wet seal surface formed by bending the periphery to one side and further projecting to the side. Provided, the separator body of the portion of the oxidizing gas discharge manifold,
The manifold is formed by bending in the same direction as the peripheral bending direction to form a wet seal surface around the manifold, and bending the separator body of the fuel gas supply / discharge manifold portion in the direction opposite to the peripheral bending direction. A wet seal surface is formed in the periphery, and the upper and lower edges are bent outward to provide flexibility in the vertical direction, and the bent portion is brought into contact with the back surface of the wet seal surface around the separator body by metal touch. A cathode rail formed into a cylindrical shape according to the shape of the separator body is placed around the separator body, and the bent portion of the cathode rail is brought into contact with the back surface of the wet seal surface around the separator body to remove oxidizing gas. Sealing is performed, and a distributor is arranged in the manifold section. A gas passage is formed on both sides of the generator body, and a hole is formed in the side wall of the cathode rail located on the side where the fuel gas supply manifold is provided, which communicates with the gas passage of the oxidizing gas formed on one surface of the separator body. A separator for a molten carbonate fuel cell, wherein an oxidizing gas can be supplied from the outer periphery of the stack to the gas passage of the oxidizing gas through the holes. 3. The oxidizing gas discharge manifold is located at the center, and holes are formed in opposite cathode rails on the fuel gas supply / discharge side, and oxidizing gas is supplied through the holes. For molten carbonate fuel cells. 4. A separator body is provided with only a fuel gas supply / discharge manifold, holes are provided in opposite cathode rails, and one of the cathode rail holes is used for supplying oxidizing gas, and the other cathode rail is provided. 3. The separator for a molten carbonate fuel cell according to claim 1, wherein the holes are used as a manifold for discharging an oxidizing gas.