JPH11191419A - Fused carbonate fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the increase in contact resistance caused by unevenness on the surfaces of an electrode and an electrolyte plate. SOLUTION: A tape 7 is interposed between an electrolyte holding plate 1a and a cathode plate 2a and between the electrolyte holding plate 1a and an anode plate 3a, then they are integrated into a cell. The tape 7 is formed such that 0.1-10 wt.% ceramics powder is added to carbonate powder, then they are mixed with a binder, a plasticizer, and a dispersant in an organic solvent to prepare slurry, and the slurry is formed in a tape by a doctor blade process. After a cell has been assembled, the cell is heated before operation, when an electrolyte plate 1 is formed by applying degreasing and impregnation to the electrolyte holding plate, the carbonate in the tape is melted and impregnated in the electrolyte plate 1, the cathode plate 2, and the anode plate 3, and a ceramic porous layer 8 is formed between the electrolyte plate and the cathode plate and between the electrolyte plate and the anode plate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molten carbonate type fuel cell among fuel cells used in the energy sector which directly converts chemical energy of fuel into electric energy.

[0002]

2. Description of the Related Art As shown in an example in FIG. 4, a molten carbonate fuel cell comprises an electrolyte plate 1 in which a molten carbonate is impregnated into a porous electrolyte holding plate as an electrolyte, and a cathode (oxygen electrode) 2 By sandwiching the anode (fuel electrode) 3 between the two electrodes from both sides, supplying an oxidizing gas to the cathode 2 and supplying a fuel gas to the anode 3, the cathode 2 and the anode 3 react with each other. A cell in which power is generated by a potential difference generated between the cathode 2 side and the anode 3 side is defined as one cell C, and the cells C are stacked via a separator 4 to form a stack.
5 is a gas passage formed on the cathode 2 side of the separator 4,
Reference numeral 6 denotes a gas passage formed on the anode 3 side of the separator 4.

In the molten carbonate fuel cell constructed as described above, a raw material powder is mixed and dispersed with a dispersant and an organic solvent, and then a binder and a plasticizer are mixed to form a slurry. The cathode and anode electrodes are superimposed on the electrolyte holding plate formed into a tape shape by the doctor blade method so as to be in direct contact with each other, and then incorporated into the battery.
The battery is heated to perform a degreasing treatment for removing organic substances such as a binder and a plasticizer by heating to make the electrolyte holding plate porous, and impregnated with a molten carbonate as an electrolyte to impregnate the electrolyte holding plate to form an electrolyte plate 1. In addition, in general, the electrode body is also made into a porous electrode by firing, and both the cathode 2 and the anode 3 are directly laminated on the electrolyte plate 1 in general.

However, the electrolyte plate 1 and the cathode 2,
The electrodes of the anode 3 are not brought into a uniform contact state over the entire surface due to the unevenness of the respective surfaces, and a gap is formed between the two to increase the contact resistance, which causes a decrease in battery performance.

Therefore, conventionally, a binder, a plasticizer and a dispersant are dissolved in an organic solvent and added to a conductive powder such as Ni or a Ni alloy or a γ-lithium aluminate powder to form a slurry. In 40 ~
When a battery is assembled, a flexible green sheet formed into a sheet having a thickness of 100 μm is interposed between the electrolyte holding plate and the electrode body to assemble the battery, and the electrolyte holding plate and the electrode body are assembled. It has been proposed that the green sheet is deformed according to the unevenness of the surface of the electrolyte holding plate and the electrode body and brought into contact without any gap by pressure bonding to reduce the contact resistance. Kaihei 2-155
No. 72).

[0006]

However, in the case where the above-mentioned green sheet is interposed between the electrolyte holding plate and the electrode body, when the battery is heated to perform a degreasing treatment before the battery operation, the green sheet is not removed. However, since the metal powder is sintered, it is difficult to control the pores, and the thickness of the sheet is also as large as 40 to 100 μm.

Further, a ceramic slurry or paste can be applied to the concave portions of the electrodes or the electrolyte plate, but it is difficult to maintain the flatness and the work is troublesome.

Accordingly, the present invention is intended to increase the adhesion between members such as an electrolyte plate and an electrode, and between an electrolyte plate and an electrolyte plate so as to reduce the contact resistance.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention has a structure in which both cathode and anode electrodes are laminated on both surfaces of an electrolyte holding plate, or a structure in which electrolyte holding plates are laminated and cathodes are formed on both sides thereof. The two electrodes, the anode and the anode, are stacked and assembled into a battery, heated before battery operation to remove organic matter from the electrolyte holding plate to form a porous electrolyte holding plate, which is impregnated with molten carbonate to form an electrolyte plate. In the molten carbonate fuel cell, in which the oxidizing gas is supplied to the cathode side and the fuel gas is supplied to the anode side, between the electrolyte holding plate and the electrode or between the electrolyte holding plates,
A tape is prepared by adding 0.1 to 10% by weight of ceramic powder to carbonate powder, further adding a binder, a plasticizer, and a dispersant in an organic solvent and mixing to form a slurry to form a slurry. By interposing, heating after the battery is assembled, the carbonate in the tape is melted and impregnated into the electrolyte plate and the electrode, and a porous layer of ceramic is formed between the electrolyte plate and the electrode and between the electrolyte plates. Configuration.

[0010] The ceramic porous layer formed between the members such as the electrolyte plate and the electrode enhances the adhesion of the members, and the porous layer of the ceramics holds the carbonate so that the contact resistance is reduced. Is reduced.

[0011]

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. As in the case of the molten carbonate fuel cell shown in FIG. 4, a dispersant and an organic solvent are added to the raw material powder. After mixing and dispersing the mixture, a binder and a plasticizer are mixed into a slurry, and the slurry is formed into a tape shape by a doctor blade method. The bodies 2a and 3a are stacked so as to overlap each other, incorporated into a battery, and heated during battery operation to remove organic substances such as a binder and a plasticizer in the electrolyte holding plate 1a to form a porous electrolyte holding plate and an electrode. The bodies 2a and 3a are also made into porous bodies by firing, and the carbonate filled in the battery is melted and impregnated (impregnated) into the porous electrolyte holding plate to form the electrolyte plate 1. Oite, prior to incorporation into the battery by laminating the cathode electrode 2a and the cathode electrode 3a to the electrolyte retention plate 1a, electrolyte reservoir plate 1a and the cathode electrode member 2
a, and a tape 7 made by mixing a ceramic powder and a carbonate powder, which is a feature of the present invention, is interposed between the electrolyte holding plate 1a and the anode electrode body 3a. And heated during battery operation to convert the electrode from the electrode body, to degrease the electrolyte holding plate 1a, the tape 7, and to melt the carbonate filled in the battery to the porous electrolyte holding plate 1a. , The carbonate in the tape 7 melts and impregnates the electrolyte plate 1, the cathode 2, and the anode 3, and includes irregularities between members of the electrolyte plate 1, the cathode 2, and the anode 3. The structure is such that the ceramic porous layer 8 is formed on the interface layer.

More specifically, the tape 7 is manufactured as follows.

[0014] First, the carbonate powder is added with a particle size of 0.1 to 10 µm.
0.1 to 10% by weight of a ceramic powder is added and mixed, and the mixture is dissolved in an organic solvent together with a binder, a plasticizer, and a dispersant to form a slurry. And

As the above carbonate, Li / K carbonate, L
i / Na carbonate, Li / K / Na carbonate, etc. are used, and as the ceramic powder, α-lithium aluminate, β-lithium aluminate, γ-lithium aluminate, zirconia, alumina Use a stable one in isomelted carbonate.

Furthermore, the reason why the addition amount of the ceramic powder to be added to the carbonate powder is 0.1 to 10% by weight is that when the amount is more than 10% by weight, it is difficult to control the formation of pores in the interface layer, so that it is more difficult than when no addition is made. This is because the contact resistance also increases.

In the molten carbonate fuel cell of the present invention, the tape 7 produced as described above is interposed between the electrolyte holding plate 1a, the cathode electrode body 2a and the anode electrode body 3a before being incorporated into the cell. In this state, the battery is incorporated as a cell in the battery, and then heated before the battery is operated to form the porous cathode 2 and the anode 3 from the electrode bodies 2a and 3a. Then, the electrolyte retaining plate 1a is degreased and impregnated so as to function as the electrolyte body 1. Further, the tape 7 is degreased to remove and remove organic substances such as binders and to melt carbonates. By being impregnated into the electrolyte plate 1 and the electrodes of the porous cathode 2 and anode 3,
The tape 7 is a porous body of ceramics,
The structure is such that a ceramic porous layer 8 is formed between these members and remains between the electrodes 2 and 3.

Thus, as shown in FIG. 1 (a), even if the gap is formed between the electrolyte holding plate 1a, the electrode bodies 2a, 3a and the tape 7 due to the unevenness on the surface, the ceramic porous As shown in FIG. 1 (b), the electrolyte layer 8 is in close contact with the interface layer between the electrolyte plate 1 and the cathode 2 and the electrolyte layer 1 and the anode 3 having irregularities on the surface. The adhesion between the cathode 2 and the anode 3 can be enhanced, and the molten carbonate is retained in the ceramic porous layer 8 by capillary action, so that the contact resistance can be reduced.

In the above description, the binder used in the production of the tape 7 used in the present invention has a higher decomposition temperature than the binder used in the production of the electrolyte holding plate so that the tape 7 is interposed between the members and functions as a buffer. Higher is preferred.

Next, FIGS. 2A and 2B show another embodiment of the present invention, in which the electrolyte plates 1 are stacked so that the cathode 2 and the anode 3 are stacked vertically symmetrically. The tape 7 manufactured in the same manner as in the embodiment of FIGS. 1 and 2 is applied to the fuel cell having the configuration described above, and the electrolyte holding plate 1a and the electrode 7 are formed in the same manner as in the embodiment. In addition to being interposed between the bodies 2a and 3a,
FIG. 2 (b) is also provided between the electrolyte holding plates 1a, incorporated in the battery and heated to perform degreasing and impregnation.
As shown in FIG. 1, a porous layer 8 of ceramics is formed between the electrolyte plates 1 as well. Fig. 1 (a)
The same components as those in (b) are denoted by the same reference numerals.

Also in this embodiment, the adhesion between the electrolyte plates 1 can be increased and the contact resistance can be reduced by the ceramic porous layer 8 formed between the electrolyte plates 1 having irregularities on the surface. .

[0022]

EXAMPLES Next, the present inventors added carbonate powder to a particle size of 0.
A tape 7 obtained by adding 0.1 to 10% by weight of ceramic powder of 1 to 10 μm, adding a binder, a plasticizer, and a dispersant in an organic solvent to form a slurry, and forming the slurry into a tape by a doctor blade method. A description will be given of the result of a test in which the resistance is measured.

FIG. 3 shows the relationship between the amount (% by weight) of ceramic powder and the resistance (mΩ) at the time of tape production. The resistance increases when the amount of ceramic powder added is in the range of 0.1 to 10% by weight. And most preferably 2 to 6% by weight
It can be seen that it is.

[0024]

As described above, according to the molten carbonate fuel cell of the present invention, the carbonate powder has a particle size of 0.1 to 0.1 between the electrolyte holding plate and the electrode or between the electrolyte holding plates. 10 μm
0.1 to 10% by weight of ceramic powder is added, and a binder, a plasticizer, and a dispersant are mixed in an organic solvent to form a slurry. When the impregnation is performed to form an electrolyte plate, the carbonate in the tape is melted to melt the electrolyte plate,
By impregnating the electrodes, a porous layer of ceramic is formed between the electrolyte plate and the electrode or between the electrolyte plates. The porous layer can enhance the adhesion, and the porous layer of the ceramic retains the molten carbonate by capillary action, thereby reducing the contact resistance and improving the battery performance. This can provide an excellent effect.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention, in which (a) is a schematic cross-sectional view showing a state in which a tape is interposed between an electrolyte holding plate and an electrode, and (b) is assembled into a battery and heated. FIG. 3 is a schematic cross-sectional view showing a state in which the carbonate has been melted and the tape has become a porous layer of ceramics.

FIG. 2 shows another embodiment of the present invention.
Is a schematic cross-sectional view showing a state in which a tape is interposed between the electrolyte holding plates, and (b) shows a state in which the tape is incorporated into a battery and heated to melt the carbonate, thereby forming the tape into a porous layer of ceramics. It is an outline sectional view.

FIG. 3 is a diagram showing the results of a resistance measurement test of a tape.

FIG. 4 is a schematic sectional view showing an example of a molten carbonate fuel cell.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electrolyte plate 1a Electrolyte holding plate 2 Cathode 2a Cathode electrode body 3 Anode 3a Anode electrode body 7 Tape 8 Porous layer of ceramics

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Akira Suzuki 3-1-1-15 Toyosu, Koto-ku, Tokyo Ishikawajima Harima Heavy Industries, Ltd. (72) Yoshikazu Yamamasu 3-1-1, Toyosu, Koto-ku, Tokyo No. Ishikawajima Harima Heavy Industries, Ltd.

Claims (3)

[Claims] 1. A battery comprising a cathode and an anode which are laminated on an electrolyte holding plate and assembled into a battery, and heated before operation of the battery to remove organic matter from the electrolyte holding plate to form a porous electrolyte holding plate. In a molten carbonate fuel cell in which an electrolyte plate is impregnated with the carbonate thus obtained, an oxidizing gas is supplied to the cathode side, and a fuel gas is supplied to the anode side, the electrolyte plate is provided between the electrolyte holding plate and the electrode. A tape prepared by adding 0.1 to 10% by weight of ceramic powder to carbonate powder, further adding a binder, a plasticizer, and a dispersant in an organic solvent and mixing to form a slurry to form a tape; And then heating after assembling the battery to melt the carbonate in the tape, impregnate the electrolyte plate and electrode, and form a porous ceramic layer between the electrolyte plate and electrode. A molten carbonate fuel cell. 2. A porous electrolyte comprising: laminating electrolyte holding plates; symmetrically laminating both cathode and anode electrodes; incorporating the battery into a battery; removing the organic matter from the electrolyte holding plate by heating before operating the battery; In a molten carbonate fuel cell in which a holding plate and a molten carbonate are impregnated to form an electrolyte plate, and an oxidizing gas flows to a cathode side and a fuel gas flows to an anode side, respectively, Between the plate and the electrode and between the electrolyte holding plates, 0.1 to 10% by weight of ceramic powder is added to carbonate powder, and a binder, a plasticizer and a dispersant are added and mixed in an organic solvent to form a slurry. The tape is formed by forming the tape into a tape, and the tape is interposed, heated after the battery is assembled, and the carbonate in the tape is melted to impregnate the electrolyte plate and electrode. A molten carbonate fuel cell having a structure in which a porous layer of ceramics is formed between the fuel cell and the electrolyte plates. 3. A tape having a particle size of 0.
3. The molten carbonate fuel cell according to claim 1, wherein ceramic powder of 1 to 10 [mu] m is added.