JPH0782863B2 - Method for producing molten carbonate fuel cell laminate - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for manufacturing a molten carbonate fuel cell stack, particularly, easy stacking and assembling, and improving electrical contact between cell parts. The present invention relates to a method for producing a molten carbonate fuel cell laminate capable of being made uniform.

[Technical background of the invention and its problems]

In recent years, a molten carbonate fuel cell has been developed as a highly efficient energy conversion device. A molten carbonate fuel cell causes an electrode reaction by causing an electrolyte composed of an alkali carbonate to melt at high temperature, and causes an electrode reaction compared to other fuel cells such as phosphoric acid type and solid electrolyte type. It is easy and does not require an expensive noble metal catalyst, and has major features such as high power generation thermal efficiency.

By the way, in order to construct a high-output power plant with a molten carbonate fuel cell, since the output of the unit cell is weak, a plurality of unit cells are laminated in series to form a laminated body,
It is necessary to obtain the added output of each unit battery.

FIG. 4 shows a conventionally proposed laminated structure. Each unit cell 1 has a pair of porous electrodes, that is, an oxidant electrode (cathode) 2a and a fuel electrode (anode) 2b,
The electrolyte layer 3 made of carbonate is interposed between them. Each of these unit batteries 1 is laminated via a conductive separator 4 having both an electrical connection function between the unit batteries 1 and a function of forming a passage of a reaction gas to each electrode plate.

The separator 4 includes a conductive separator plate 5, a side wall member 6a made of stainless steel, for example, brazed and fixed to two opposing sides of one surface of the separator plate 5, and the other surface of the separator plate 5. Then, the side wall member 6b made of stainless steel, for example, is brazed and fixed to two opposite side portions in the direction orthogonal to the side wall member 6a, and the reaction gas passages 7a, 7b formed by these side wall members 6a, 6b are fitted. It is composed of corrugated plates 8a, 8b that are combined to divide the reaction gas.

A manifold (not shown) having a function of distributing and recovering the reaction gas is applied to the four side surfaces of the fuel cell stack X thus configured. Then, the oxidant gas P is supplied to one of the manifolds, and the fuel gas Q is supplied to the adjacent manifold so that both the gases contribute to the electrode reaction inside the fuel cell stack X, and the DC output is generated. After being obtained, the exhaust gas can be exhausted from each of the opposing manifolds.

However, in the fuel cell stack having the above structure, the electrolyte layer 3, the cathode 2a, and the
It is necessary to stack the separators 4 in order while confirming their mutual positions, which causes a problem that the stacking procedure is complicated and the assemblability is poor.

Further, in order to ensure good contact between cell parts such as electrodes and corrugated plates, there is also a problem that these require high thickness accuracy.

[Object of the Invention]

The present invention has been made in view of the above circumstances, and has a small number of laminated components, easy assembly, and a reliable molten carbonate fuel cell laminate capable of ensuring mutual contact between cell components. It is intended to provide a manufacturing method.

[Outline of Invention]

In order to achieve the above object, the present invention provides a unit cell comprising an oxidizer electrode on one surface of an electrolyte plate made of molten carbonate and a fuel electrode on the other surface, and a conductive separator. In a method for manufacturing a molten carbonate fuel cell laminate in which a plurality of layers are laminated with a gas splitting element disposed in an oxidant gas passage formed by engaging a separator plate and a perforated current collector plate. And forming the first combined body by disposing the oxidizer electrode so as to contact the perforated current collector plate, and the end of the member forming the fuel gas passage is formed with a gas shield plate. A step of forming a second combined body by arranging the fuel electrode so as to cover and contact a member forming the fuel gas passage, and the oxidant electrode and the fuel electrode respectively contact the electrolyte plate. Such that the first combination and the second combination It is characterized by a step of laminating.

〔The invention's effect〕

According to the present invention, a separator plate, a gas flow dividing element, a perforated current collector plate and an oxidizer electrode are integrally combined in advance as a first combined body, a member forming a fuel gas passage, a gas blocking plate and a fuel electrode. Since the fuel cell stack is assembled by sequentially stacking the three elements of the second combined body in which the above are integrally connected with each other and the electrolyte plate, the complexity of positioning between the cell parts is reduced, and the stacking is reduced. Easy to assemble.
Further, since the contact between the cell parts is also good, it is possible to contribute to the high output of the fuel cell.

Example of Invention

Hereinafter, a molten carbonate fuel cell laminate to which an embodiment of the manufacturing method according to the present invention is applied will be described with reference to FIGS. 1 and 2.

This fuel cell stack Y has a first electrode on one surface of the electrolyte plate 11.
The laminated body 12 is arranged, and the second laminated body 13 is arranged on the other surface of the laminated body 12 . In this case, the supply / discharge surfaces of the fuel gas Q in the fuel cell stack Y are A and A ′ surfaces, and the supply of the oxidant gas P is
The discharge surfaces will be referred to as the B and B ′ surfaces, respectively.

The electrolyte plate 11 is formed in a plate shape by hot pressing, for example, by mixing a carbonate electrolyte powder and a holding ceramic powder.

The first combined body 12 is the essential part of this embodiment, and FIG. 2 is an exploded perspective view thereof. That is, the first combined body 12 is one in which the separator plate 21, the corrugated plate 22, the perforated current collector plate 23, and the cathode 24 are laminated as shown in the figure and integrally combined. The separator plate 21 is a plate-shaped body A,
The opposite side portion located on the A ′ surface is bent downward by the thickness of the corrugated plate 22, and the perforated current collector plate 23 is a separator plate.
It is formed by providing rising portions at four corners that fit with the L-shaped end faces of the bent portions of 21. These separator plates 21, corrugated plates
The perforated current collector 22 and the perforated current collector 23 can be formed, for example, by plating a stainless steel plate having a thickness of 0.3 mm. And
The separator plate 21 and the perforated current collector plate 23 are welded to each other at the portions located on the A and A ′ surfaces and the L-shaped end surface portion (C end surface), and the corrugated sheet 22 is contacted with the separator plate 21 at a predetermined portion (point D). The three are integrated by spot welding. Also, the cathode 24
Is, for example, nickel oxide particles are mixed with an aqueous solution of lithium hydroxide (saturated) to form a slurry, which is then heat treated in air at 850 ° C. to form lithium nickel oxide,
The secondary particles having a diameter of about 10 μm are uniformly mixed with a polyethylene binder in a ratio of 95: 5 (weight ratio) in a pot mill, and a sheet having a thickness of about 1 mm is formed by a hot roll. The cathode 24 is pressure-bonded to the lower surface of the perforated current collector plate 23 at about 80 ° C. At this time, in the portion located on the A, A ′ surface between the perforated current collector plate 23 and the cathode 24, a sealing material 25 mainly composed of boric acid glass having a low melting point is used.
Is installed. The sealing material 25 melts when the temperature of the fuel cell rises and soaks into the end portion of the cathode 24 to form a wet seal.

In the second combined body 13 , an anode 32 is arranged on the upper surface of a high-porosity porous metal plate 31 for flowing a fuel gas, and further, this combined body is formed.
The end portions located on the B and B'sides are covered with a gas shielding plate 33 and integrated.

And these first combinations12And a second combination13
The cathode 24 and the anode 32 on the electrolyte plate 11, respectively.
So that they are in contact with each other and the gas flow paths are orthogonal to each other
When the fuel cell stack Y is arranged on both sides of the electrolyte plate 11,
To be done. As a result, the electrolyte plate 11 of the fuel cell stack Y is
Unit battery with cathode 24 and anode 3241Is formed,
Separator with other cell parts42Is formed.

The present inventors construct the above fuel cell stack Y, apply a conductive end plate (not shown) from above and below the fuel cell stack Y, and after tightening, include a low melting point glass on each side surface. A manifold (not shown) for guiding the reaction gas was attached via a sealing material. And this fuel cell 42
The temperature was raised to 0 ° C., and air was passed as the oxidant gas P at 420 ° C. to volatilize the polyethylene binder of the cathode 24. Thereafter, the temperature is further raised to 650 ° C., air / carbon dioxide gas as the oxidant gas P is allowed to flow from the B surface to the B ′ surface, and hydrogen / carbon dioxide gas as the fuel gas Q is transferred from the A surface to the A ′ surface. It was made to flow and it made it generate electricity. As a comparative example, a power generation experiment was similarly conducted using the conventional fuel cell stack X shown in FIG.

As a result, in the laminated body Y of the present example, the ohmic resistance per unit cell was reduced by 0.2 Ω · cm ² as compared with the laminated body X of the comparative example, and the voltage per unit cell of 0.15 A / cm ² was 30 mV. It became higher and the contact between cell parts was better.

According to this embodiment, the first part forming a part of the separator 42
Since the combined body 12 is made of a combination of thin metal plates, the manufacturability is of course good, and in this case, the seal made of stainless steel muku material as shown in FIG. Since the side wall members 6a and 6b for the fuel cell are not required, the weight of the fuel cell can be reduced.

Further, since the cathode 24 and the perforated current collector plate 23 are integrated, the number of parts at the time of assembly is small, the assembly process can be reduced, and the parts can be easily aligned with each other.

Further, as is apparent from the reduction of ohmic resistance during the power generation test, the contact resistance between the cathode 24 and the separator 42 is reduced by integrally forming the cathode 24 and the separator 42 , and the cathode 24 contains an organic binder to be flexible. Because I have
The contact between the cathode 24 and the electrolyte plate 11 was also good.

The present invention is not limited to the above embodiment.

For example, the first combined body 12 described above may be configured as shown in FIG. The first combined body 51 is formed by bending the end portion of the separator plate 52 downward, and further performing sheet metal processing so that the bent portion is bent inward so that the end faces of these bent portions are connected to each other. A flat plate-shaped perforated current collector plate 53 is fixed by welding.

Further, the surface of the perforated current collector plate on the side in contact with the cathode may be treated with electrochemical lithium oxide to form lithiated nickel oxide. Cathode, instead of those using nickel oxide powder, or in addition to _{LiFeO 2, Li 2 MnO 3,} L
aNiO _3, LaCoO ₃ may be used. Although an aqueous solution of LiOH was used for lithiation of nickel oxide, an aqueous solution of Li acetate may be used.

In addition, the present invention uses a corrugated plate similar to the cathode side instead of the metal porous plate for gas flow on the anode side,
Further, various modifications are conceivable without departing from the scope of the invention, such as welding and integrating the first combined body 12 and the second combined body 13 .

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing the configuration of a molten carbonate fuel cell stack to which an embodiment of the manufacturing method according to the present invention is applied,
FIG. 2 is an exploded perspective view of a first combined body in the same laminated body,
FIG. 3 is an exploded perspective view of a first combined body of a molten carbonate fuel cell stack to which another embodiment of the manufacturing method according to the present invention is applied, and FIG. 4 is a conventional molten carbonate fuel cell stack. It is an exploded perspective view showing composition of a body. 1 , 41 …… Unit battery, 2a, 24 …… Cathode, 2b, 32 …… Anode, 3 …… Electrolyte layer, 4 , 42 …… Separator, 5,2
1, 52 ...... separator plate, 8a, 8b, 22 ...... wave plate, 11 ...... electrolyte plate, 12, 51 ...... first conjugate, 13 ...... second conjugate,
23,53 …… Perforated current collector plate, 25 …… Seal material, 31 …… High porosity metal porous plate, 33 …… Gas shielding plate, P …… Oxidizer gas, Q …… Fuel gas.

Claims (2)

[Claims] 1. A plurality of unit batteries each having an oxidizer electrode arranged on one surface of a molten carbonate electrolyte plate and a fuel electrode arranged on the other surface thereof are laminated with a conductive separator interposed therebetween. In the method for producing a molten carbonate fuel cell laminate, the gas distribution element is disposed in an oxidant gas passage formed by engaging a separator plate and a perforated current collector plate, and the perforated current collector is provided. A step of forming the first combined body by disposing the oxidizer electrode so as to contact the electric plate; and a step of covering the fuel gas passage with an end portion of a member constituting the fuel gas passage covered with a gas shielding plate. A step of forming a second combined body by disposing the fuel electrode so as to be in contact with a constituent member; and the first oxidizer electrode and the fuel electrode being in contact with the electrolyte plate, respectively. Laminating a combined body and the second combined body. Method of manufacturing a molten carbonate fuel cell stack, characterized in that. 2. The oxidizer electrode is formed by a step of mixing a lithiated metal oxide and an organic binder into a sheet, and press-bonding the sheet to the perforated current collector plate. 2. A method for producing a molten carbonate fuel cell laminate according to claim 1.