JPH0845533A - Fuel cell - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent the deformation of the end separator due to the joining of the end separator of the manifold and the holder. [Structure] End plate 23 of end separator 23
One end of the metal bellows 24 is welded over the entire circumference to the peripheral edges of the manifolds 5 and 7 provided in a (welding portion 25).
The other end of the metal bellows 24 is welded over the entire circumference to the inner surfaces of the manifolds 5, 7 of the lower holder 11 located at the positions corresponding to the manifolds 5, 7 (welding part 2
6). Even if the end separator 23 and the lower holder 11 having different thermal expansion amounts become hot and a difference in thermal expansion occurs, the end plate 23a of the end separator 23 and the lower holder 11 are indirectly joined by the metal bellows 24. The deformation of the end separator 23 can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell used in the energy sector for directly converting chemical energy of fuel into electric energy.

[0002]

2. Description of the Related Art Among fuel cells, for example, a molten carbonate fuel cell has a tile (electrolyte plate) 1 obtained by impregnating a molten carbonate as an electrolyte with a porous material as a cathode as shown in FIG. (Oxygen electrode) 2 and anode (fuel electrode)
It is sandwiched by both electrodes of No. 3 from both sides, and the oxidizing gas O
One cell C is configured so that power is generated by a chemical reaction between the cathode 2 and the anode 3 by supplying G and fuel gas FG to the anode 3 side,
Each cell C is laminated in multiple layers via the separator 4 to form a fuel cell stack.

Further, when the fuel cell is of the internal manifold type, the oxidizing gas OG is flowed in the stacking direction to each side of the peripheral portion of the tile 1 constituting the cell C and the peripheral portion of the separator 4 partitioning each cell. A plurality of oxidizing gas supply manifolds 5 for distributing to the cathode 2 side of each cell
And a plurality of fuel gas supply manifolds 7 arranged so as to distribute the fuel gas FG in the stacking direction to the anode 3 side of each cell, and to the other side of the peripheral portion,
A plurality of oxidizing gas discharge manifolds 6 for allowing the oxidant gas OG discharged from the cathode 2 of each cell to flow and a plurality of fuels for allowing the fuel gas FG discharged from the anode 3 of each cell to flow. The gas discharge manifold 8 is arranged side by side.

In the above fuel cell, it is necessary that the cell performance is maintained good for each cell C stacked via the separator 4, and each electrode of the cathode 2 and the anode 3 and the tile 1 are provided in the cell reaction section. And the separator 4 are in contact with each other with a uniform tightening pressure distribution, in an internal manifold type fuel cell, the wet sealability of the peripheral portion is maintained, and the stack height during operation is high. Since it is required to follow changes and the like, it is necessary to uniformly tighten the entire fuel cell with a constant tightening force.

Therefore, conventionally, as shown in FIG. 3, as an example, a fuel cell stack 9 formed by stacking cells in multiple layers is held by upper and lower holders 10 and 11, and a lower bolster 14 is held.
The upper bolster 13 is placed on the upper holder 10 with the metal bellows or cushion 12 interposed therebetween, and the upper and lower bolsters 13 and 14 are tightened by the tightening rod 15 and the nut 16 to remove the fuel. There is one in which a predetermined tightening force is applied to the battery stack 9.

Further, in order to further increase the number of stacked layers of cells, as shown in FIG. 4, the fuel cell stack 9 having a high stack is divided into upper and lower parts into an upper stack 9a and a lower stack 9b, and legs 17 are provided. The upper holder 10 and the metal bellows or cushion 12 and the upper bolster 13 are arranged above the upper stack 9a and the lower stack 9b is arranged below the lower stack 9b. , The lower holder 11, the metal bellows or cushion 12, and the lower bolster 14 are arranged so that the upper and lower bolsters 13 and 14 are respectively tightened by the tightening rod 15 and the nut 1.
The upper and lower stacks 9 are supported by the intermediate holder 18 at 6.
It is also proposed that a and 9b are provided with a predetermined tightening force.

In the fuel cell in which a predetermined tightening force is applied by the tightening device as described above, in the case of the internal manifold type, the lower holder 11 in the type shown in FIG.
The oxidizing gas supply side header 19 and the discharge side header 20 and the fuel gas supply side header 21 and the discharge side header 22 are connected to one side and the other side, respectively, and the manifold 5 provided in the peripheral portion of the lower holder 11 is connected. , 6, 7, 8 to fuel cell stack 9 through oxidation gas OG and fuel gas FG
Of the intermediate holder 18 in the model shown in FIG.
Headers 19, 20, 21, 22 similar to the above are connected so that the oxidizing gas OG and the fuel gas FG are supplied to and discharged from the upper and lower holders 9a, 9b.

The portion of the stack 9 that contacts the lower holder 11 shown in FIG. 3 and the portions of the stacks 9a and 9b that contact the intermediate holder 18 shown in FIG. 4 are, for example, those shown in FIG. ) (B), the end separator 23 is arranged between the lower holder 11 and a stack formed by stacking the cells C in which the tile 1 is sandwiched by both electrodes of the cathode 2 and the anode 3 from both sides with the separator 4 interposed therebetween. There is a configuration.

The separator 4 is an example,
A center plate 4a, a cathode side mask plate 4b and an anode side mask plate 4c arranged on both surface sides of the center plate 4a, and a corrugate for forming a gas passage arranged between the center plate 4a and both mask plates 4b, 4c. The end separator 23 is a half of the separator 4 and includes an end plate 23a, a mask plate 23b arranged only on one side of the end plate 23a, and an end plate 23.
a and a corrugate 23c arranged between the mask plate 23b, and the end separator 23 is similar to the separator 4 as shown in the plan view of FIG.
An oxidizing gas supply manifold 5 and a fuel gas supply manifold 7 are alternately provided on one side of the peripheral portion, and an oxidizing gas discharge manifold 6 and a fuel gas discharge manifold 8 are provided on the other side of the peripheral portion. The electrodes are provided alternately, and the electrodes are arranged in the cutout portion in the central portion of the mask plate 23b.

In the case of the molten carbonate fuel cell, since corrosive molten carbonate is used as the electrolyte, the material used for the separator 4 and the end separator 23 is highly corrosive, but Since the cost of using the same material as the separator for the object holder is high, the separator is usually made of SUS310S coated with nickel clad, whereas
SUS316L is used for the holder.

[0011]

However, the materials used for the separator and the holder are different, and the SUS310S
And SUS316L have a thermal expansion difference (the amount of thermal expansion is SUS31
Despite 0S <SUS316L), the conventional model is shown in FIG.
As shown in (b), since the end separator 23 and the holder 11 are directly welded to each other for the purpose of preventing gas leakage at the manifold portion and making electrical contact, the fuel cell is operated. Has started 6
When the temperature of the stack and the holder is increased to 00 ° C. to 700 ° C. and the temperature of the stack and the holder is increased, a difference in thermal expansion occurs between the end separator 23 and the holder 11, and the end separator 23 expands. When the holder 11 contracts when the temperature is lowered, the separator 23 is deformed without being contracted even if the holder 11 contracts, resulting in non-uniform tightening surface pressure and deterioration of battery performance and tile cracking. There is a problem that causes.

Therefore, the present invention is intended to prevent deformation of the separator due to a difference in thermal expansion between the separator and the holder, prevent gas leakage, and ensure electrical contact.

[0013]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a metal bellows between each manifold of an end separator in a portion in contact with a holder of a fuel cell stack and each manifold of the holder. And one end of each bellows is welded to the peripheral edge of the manifold of the end separator, and the other end of the bellows is welded to the inner surface of the manifold of the holder.

[0014]

[Function] When the temperature of the stack and the holder becomes high during the operation of the fuel cell, a difference in thermal expansion occurs between the end separator and the holder. However, since both are connected by the metal bellows in the manifold, the thermal expansion The difference can be absorbed by the bellows to prevent the end separator from being deformed. Gas leakage between the end plate and the holder is prevented by the bellows, and the flow of electricity is performed through the welded portion between the metal bellows and the end separator, the bellows, and the welded portion between the bellows and the holder.

[0015]

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

FIGS. 1A and 1B show an embodiment of the present invention, in which the stack 9 and the lower holder 11 of the internal manifold type fuel cell shown in FIGS. Similarly, the end separator 23 at the end of the stack 9 on the side of the holder 11 is connected to the manifolds 5 and 6 for supplying and discharging the oxidizing gas.
Part, the mask plate 23b of the end separator 23
Is joined to the end plate 23a, the end plate 23a is joined to the lower holder 11, and in the fuel gas supply / discharge manifolds 7 and 8, the end plate 23a
In the structure in which a is joined to the lower holder 11, the oxidizing gas supply / discharge manifold (the supply side manifold 5 is shown in FIG. 1 (a)) portion of the end plate 23a of the end separator 23 and the fuel gas supply / discharge manifold Metal bellows 24 are respectively arranged in the portion (showing the supply side manifold 7 in FIG. 1B), and one end of the bellows 24 is welded to the peripheral edge of the manifold of the end plate 23a over the entire circumference (welding portion). 25) with bellows 2
The other end of 4 is the manifold of the lower holder 11 (see FIG.
(A) (b) shows the supply side manifolds 5 and 7 for the oxidizing gas and the fuel gas, and the lower holder 1
The inner surfaces of the manifolds 5 and 7 of No. 1 are welded and joined (welded portion 26) over the entire circumference, and the end separator 23 and the lower holder 11 are indirectly connected to each other via the metal bellows 24.

By operating the fuel cell, the end separator 2
When heat is conducted from 3 to the lower holder 11, a difference in thermal expansion occurs between the end plate 23a of the end separator 23 and the lower holder 11 due to the difference in material between them, but in this case, the metal bellows 24 Since it can be absorbed by expansion and contraction of the end plate 23a, the end plate 23a will not be deformed as in the case where the end plate 23a is directly welded to the lower holder 11. Further, since the metal bellows 24 is joined to the end plate 23a and the lower holder 11 by welding over the entire circumference, there is no gas leakage, and electrical contact can be obtained as a contact for flowing electricity.

In the above embodiment, the fuel cell stack 9 is clamped by the upper and lower holders 10 and 11 to apply a predetermined tightening force to the stack 9, as shown in FIG. Although the example in which the oxidizing gas and the fuel gas are supplied and discharged by using the above is illustrated, as shown in FIG. 4, in the model in which the intermediate holder 18 is highly stacked, the intermediate holder 18 is used for the oxidation. For those that supply and exhaust gas and fuel gas,
The intermediate holder 18 and the end separators of the upper and lower stacks that are in contact with the intermediate holder 18 may be indirectly joined with a metal bellows. Further, the end separator 23 is an example, and in the manifold portion, The mask plate 23b is deformed to change the end plate 23a.
Although the case where the end plate 23a is joined to the mask plate 23b may be modified by deforming the manifold portion of the end plate 23a, other various changes may be made without departing from the scope of the present invention. Of course.

[0019]

As described above, according to the fuel cell of the present invention, the end plate of the end separator in the portion in contact with the lower holder or the intermediate holder of the fuel cell stack and the lower holder or the intermediate holder are provided with an oxidizing gas and Each fuel gas supply / discharge manifold has a structure in which it is welded over the entire circumference through metal bellows, so even if the end separator and the holder become hot, the difference in thermal expansion between them will occur. It is possible to prevent the deformation of the end separator due to the above phenomenon, prevent gas leak, and ensure electrical contact.

[Brief description of drawings]

1 shows an embodiment of the present invention, (a) is a cross-sectional view showing an oxidizing gas supply manifold part of an end separator and a lower holder, and (b) is a fuel gas supply of the end separator and a lower holder. It is sectional drawing which shows a manifold part.

FIG. 2 is a partial cross-sectional view showing an example of a fuel cell stack.

FIG. 3 is a schematic diagram showing an example of a fuel cell.

FIG. 4 is a schematic diagram showing another example of a fuel cell.

FIG. 5 shows a conventional fuel cell, in which (a) is a cross-sectional view showing an oxidizing gas supply manifold part of a separator and a lower holder, and (b) shows a fuel gas supply manifold part of a separator and a lower holder. FIG.

FIG. 6 is a plan view showing an example of a separator.

[Explanation of symbols]

 5 Manifold for supplying oxidizing gas 6 Manifold for discharging oxidizing gas 7 Manifold for supplying fuel gas 8 Manifold for discharging fuel gas 9 Fuel cell stack 9a Upper stack 9b Lower stack 10 Upper holder 11 Lower holder 13 Upper bolster 14 Lower bolster 18 Intermediate holder 23 End separator 23a End plate 23b Mask plate 24 Metal bellows OG Oxidizing gas FG Fuel gas

Claims (1)

[Claims] 1. A part of a fuel cell in contact with a lower holder or an intermediate holder of a fuel cell stack, wherein an oxidizing gas and a fuel gas are supplied to and discharged from a fuel cell stack by using a lower holder or an intermediate holder. The end plate of the end separator and the lower holder or the intermediate holder are welded and joined to each other through the metal bellows at the manifold portions for supplying and discharging the oxidizing gas and the fuel gas, and both are indirectly bonded by the metal bellows. A fuel cell having a joined structure.