JPS5996669A - Fused-carbonate fuel cell - Google Patents

Abstract

PURPOSE:To obtain a fused-carbonate fuel cell which contains bipolar separators of a high absorptivity and a high electronic conductivity interposed between unit cells and which can be assembled efficiently by forming the bipolar separator by the use of a separator base body and pipes stucked to its both surfaces so as to provide gas paths. CONSTITUTION:In a fused-carbonate fuel cell, seal edge members 46a, 46b, 47a and 47b are provided on the surfaces of a metallic base body 45 for a bipolar separator 44. A number of metallic pipes 48a are stuck to the surface of the separator base body 45 located between the seal members 46a and 46b in such a manner that the pipes 48a are apart from each other thereby forming an oxydant gas path (B). A number of pipes 48b are provided on the surface of the separator base body 45 located between edge members 47a and 47b in such a manner that the pipes 48b are apart from each other thereby forming a fuel gas path (A). Such bipolar separators 44 are interposed between a number of unit cells to constitute the main part of the battery. Owing to such constitution as above, inhomogeneous distributions of the thickness of an electrolyte layer and gas-diffusing electrodes can be absorbed by the pipes 48.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a bath-molten carbonate fuel cell, and more particularly to a fuel cell with an improved bipolar separator interposed between each unit cell.

[Background technology of the invention and its problems]

2. Description of the Related Art Conventionally, fuel cells that obtain DC power by reacting a gas that is easily oxidized, such as hydrogen, and a gas that has oxidizing power, such as oxygen, through an electrochemical reaction process have been widely known. Fuel cells are broadly classified into phosphoric acid type, bath molten carbonate type, solid electrolyte type, etc. depending on the electrolyte used.

By the way, among the above-mentioned fuel cells, the molten carbonate type fuel cell is designed to operate at a temperature of around 650C, and its main parts are operated at a temperature around 650C.

Each bipolar separator 4 constitutes a passage A through which fuel gas flows, as shown by hole arrow P in the figure, on both sides of a corrosion-resistant stainless steel plate 5 having a thickness of 6 to 12 cm. The groove 6 and the groove 7 forming a passage B through which the oxidizing gas flows, as shown by the hole arrow Q in the figure, are provided in a relationship that is orthogonal to each other. Each #6 and #7 of the plate body 5, that is, the gas diffusion species, has one surface in contact with the electrolyte layer, and the other surface with the above-mentioned locking steps 8m and 8b and the groove 6 ( 7) is formed in a size that allows it to be held in position while in contact with the convex portion constituting part 7). And - the provision of the groove in the plate body 5;
k th x''.

However, there was a problem that the main part was not configured as described above. That is, as the bipolar separator 4, grooves 6,
7 is used, so does it take a long time to manufacture, or does it require too much material for the battery elements? There is a high possibility that the load will be applied and damage them. Furthermore, in the bipolar separator 4 having the above-described structure, the parts where the gas diffusion species 2a and 2bK contact each other, and the convex parts constituting the tabs 9 grooves 6 and 7, have high rigidity, so that the electrolyte layer l and the gas diffusion species,
? When the thicknesses of a and 2b are non-uniform, this cannot be absorbed, and as a result, there is a risk that overload will be locally applied to them, causing them to break.

Therefore, recently, stainless steel sealing edge members 12a, 12b and No.Ja, No.3, which have locking step portions ga and 8b on the sides to eliminate such problems, have been developed.
Bipolar separator 4 with bf welding and between edge members 12a and 12b and edge member gas passages A and B
In addition, the elasticity of the corrugated plates 14m and 14b can absorb to some extent the non-uniformity of the thickness of the electrolyte layer and the gas diffusion species 2m and 2b, and the corrugated plates 14a and J
This becomes a path for 4-bit electrons, so if the tops of the valleys of the corrugated plates 14h and 14b and the plate 1 are joined by welding in order to improve electron conductivity, the elasticity of the corrugated plates 14m and 14b decreases, and as mentioned above, There is a problem in that it cannot absorb the unevenness of the thickness. On the other hand, if the tops of the valleys of the corrugated plates 14a and 14b and the plate material 1 are not joined by welding or the like as described above, it is possible to avoid a significant deterioration in the workability during assembly and the product JJ fatness. Moreover, there is a risk that an insulating film may be formed during operation, impairing the electronic conductivity between the corrugated plates 14a and 14b and the plate material 1.In the end, this method has its advantages and disadvantages and cannot be said to be necessarily satisfactory. It was something.

Good absorbency and good polar conductivity when the shape is non-uniform [Summary of the Invention] The molten carbonate fuel cell according to the present invention is characterized by a bipolar separator. In other words, a bipolar separator consists of a separator body made of a metal material, and a cylindrical or semi-cylindrical shape that is fixed in parallel to both sides of this body and that forms the passage for each gas in the groove-like space between them. It is configured with a metal pipe. In other words, the corrugated plate explained in FIG. 2 is replaced with a metal pipe.

〔Effect of the invention〕

With the above configuration, if a thin-walled metal pipe is used, the weight can be sufficiently reduced as shown in Fig. 2, and the metal pipe can exhibit sufficient elasticity. Since it is easy to arrange electrolyte layers and gas diffusion electrodes with non-uniform outer diameters, it is also possible to make good electronic contact between each pipe and the gas diffusion electrode. By passing the oxidizing gas through the pipe located on the oxidizing electrode side, the mother tube can also be used as a cooling pipe, and as a result, all the problems of the conventional method can be solved, resulting in a successful result. It is possible to bring out the best battery characteristics.

[Embodiments of the invention]

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

FIG. 3 shows a bipolar separator 44 incorporated in the molten carbonate fuel cell according to the present invention. That is, this bipolar separator 44 has a thickness of, for example, 0.5
Separator body 45 made of trrm stainless steel copper plate
And this isolation board book! 7-! Stainless steel sealing edge members 46a, 146b and 47a, 47b are respectively fixed to both parallel sides of 5.
Above, the fibril separating plate main body 7 located between the edge members 46m and 46b. The above-mentioned -2 ji member 76 is on the surface of the .

46b and between them, a stainless steel pipe 48a formed, for example, 1.5 mm, and the edge member 47a # on the surface of the separator body 45, which is also located between the edge members 47m and 47b. 47 parallel to b,
and f-ino 48b formed in the same manner as described above, which are fixed to each other with the same spacing as above, and constitute the fuel gas passage A in the groove-like space between them. There is. Note that each edge member 46a.

At the inner line portions of 46b, 47m, and 47b, there are locking step portions 49 for locking both side line portions of the gas diffusion electrode (not shown).
is formed. Also, forming passage A, Gui f4
As shown in FIG. 4, the s& is used by crushing its midway position to prevent the flow of fuel gas into the mother iso. Further, the bipolar separator 44 as described above is manufactured, for example, as follows.

That is, as shown in FIG. 5, a boron nitride layer 65 is provided on the separator main body 45, on the pipe installation groove 62, and on the edge member surface to prevent the respective holding plates from joining with the edge member and the mother tube. is formed. Approximately 1 kji'/crn from the top of the figure is combined in this way.
A vacuum furnace (vacuum degree I x 10
Torr or higher) for 1 hour at 1000° C., further heated at 1150° C. for 30 minutes, and then slowly cooled to obtain an integrated product as shown in FIG.

Therefore, in the molten carbonate fuel cell according to the present invention, the bipolar separator 44 configured as described above is interposed between a plurality of unit cells shown in FIG. The main part is composed of this laminate.

With this configuration, when a load is connected between both end faces of the laminate, the passage A formed in each bipolar separator 44 is
and in this case, bipolar separators 44 compared to those forming each bipolar separator 44.
The weight of each piece can be reduced. Furthermore, since each pipe 48a, 48b is independently fixed to the separator body 45, when a load is applied in the direction shown by arrow C as shown in FIG. ! la, (48b
) is 48 a' in the figure.

As shown at 48b', each bends independently into an oval shape.

Therefore, the electrolyte layer 1 and the gas diffusion electrode 2a.

Even if there is a locally thick part in 2b, it is
Since it can be absorbed by the deformation of tta and 4sb, damage to the electrolyte layer 1 and gas diffusion electrodes 2a and 2b, which tends to occur when locally thick parts exist as described above, can be prevented. I can do it. Also, pipe 41jg
, 48b are fixed to the separator body 45 by welding or the like, so that assembly is possible.

1--=== is a busy semi-cylindrical mother as shown in Figure 7! 7B may also be used. By using this narrow shape, the elasticity in the load direction is inferior to that of a cylindrical shape, but the distance T4Lt' between them when deformed by a load can be kept large, so the reaction gas Effective utilization can be achieved. The main body of the separator and the error are still present in each embodiment.
) members and pipes are made of stainless steel,
The material is not limited to this, and any metal material may be used as long as it has corrosion resistance and good electronic conductivity.

[Brief explanation of the drawing]

Fig. 1 is an exploded perspective view of the main part of a conventional molten carbonate fuel cell, Fig. 2 is a perspective view showing a different example of a bipolar separator incorporated in the main part, and Fig. 3 is a perspective view of the main part of a conventional molten carbonate fuel cell. A perspective view of a bipolar separator incorporated into the main part of a molten carbonate fuel cell, No. 4: A diagram showing an example of a bipolar separator incorporated into the separator. wco g construction I89! 69. FIG. 6 is a diagram for explaining the action of the separator, and FIG. 7 is a diagram for explaining a modification of the bipolar separator. , kuto... laminate, 1... electrolyte layer, 2a + 2
b...Gas diffusion electrode, mutual...unit battery, 44...
Bipolar separator, 'pl! ”: b...edge member, 4
8 a, 48 b, 7 B -=Applicant] Makoto Ishizaka, Director of the Second Industrial Technology Agency -s 1 Ro [Figure 12 Figure 8 Figure 3 Figure 4 Figure 6 rEi

Claims (1)

[Claims] A plurality of unit cells each having a molten carbonate electrolyte layer interposed between a fuel electrode and an oxidizer electrode are formed in grooves on both sides between each unit cell.