JPS61224272A - Electrode for molten carbonate fuel cell - Google Patents

Abstract

PURPOSE:To acquire an electrode having a reinforcement wire net only on one side in a simple method, by dissolving an organic binder in a mixed solution including an organic solvent, mixing and kneading the resultant binder solution and a metallic powder to make into a slurry, spreading the slurry on one side of a reinforcement wire net to hold the slurry, and baking up the slurry on the wire net into a porous body in a plate form. CONSTITUTION:In a mixed solvent consisting of water, methyl alcohol, isopropyl alcohol, and a nonionic surface active agent, methyl cellulose is dissolved, and the resultant binder solution and nickel powder are mixed and stirred at a reduced pressure, to make the powder into a slurry. After the resultant slurry S is put into a holder hopper 5, the slurry S is spread on the upper side of a wire net 1. After the wire net 1 holding the slurry S is removed from the slurry holder hopper and dried up, a filter paper 6 is removed from the wire net 1, and then the wire net 1 is placed in an electric furnace. After the air in the furnace is replaced with hydrogen, the slurry S is maintained in a steam flow and baked up into a porous body.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a molten coal M using molten carbonate as an electrolyte.
The present invention relates to a salt fuel cell, and more particularly to a pair of positive and negative electrodes arranged on both sides of an electrolyte body in the same cell.

BACKGROUND OF THE INVENTION Electrodes in molten carbonate fuel cells are typically used in contact with molten carbonic acid 3B at operating temperatures around 650°C. As the electrode, an electrode made of a plate-shaped porous body manufactured by sintering nickel-based alloy powder is generally used in order to improve gas permeability. However, if this electrode is composed only of the above porous material, the strength of the electrode will be poor and the electrode may deform during power generation. In order to increase the strength, it is sufficient to increase the thickness, but since the thickness of the electrode is limited to 0.3 to 1.0IIIIIIVl, it is necessary to run a reinforcing material along the porous plate. come. A wire mesh made of stainless steel U4 is the best reinforcing material, but stainless steel generally corrodes when it comes into contact with molten carbonate. Therefore, in order to prevent corrosion, it is necessary to manufacture an electrode in which the wire mesh is placed only on one side of the porous plate, and to arrange the electrode so that the wire mesh is on the opposite side of the interface between the electrode and the electrolyte.

Prior art and its problems Conventionally, as a method for manufacturing a wire mesh reinforced porous plate, metal powder is kneaded with an organic binder solution by iIP to form a slurry, and 1
A method is known in which a stainless steel wire gauze is immersed in a slurry that has been quenched, and then the supported slurry is fired to form a plate-shaped porous body. A wire mesh is embedded in the porous plate, and it is not possible to obtain a porous plate with a wire mesh on one side only, which can meet the above requirements.

There is also a method of manufacturing porous plates by bonding metal mesh to metal powder that has been pre-formed by pressing and firing the bonded material, but in this case it is difficult to produce a product with a uniform thickness and a large area. .

The present invention was made in view of the above-mentioned circumstances, and an object of the present invention is to provide an electrode for a molten carbonate fuel cell made of a porous plate having a wire mesh on only one side.

Means for Solving the Problems In order to achieve the above object, the electrode according to the present invention is made by dissolving an organic binder in a mixed solvent containing an organic solvent, and kneading the obtained binder solution and metal powder to form a slurry.
A porous plate J having a wire mesh on only one side is manufactured by coating the obtained slurry on one side of a reinforcing wire mesh to support it, and firing the supported slurry to form a plate-shaped porous body.
It is characterized by becoming.

The reason for using the binder solution in this invention is as follows. Stably and uniformly disperse powder with a density similar to metal powder in binder solution 1! To do this,
It is sufficient to use a binder solution with a high viscosity, but if the viscosity is too high, the dispersibility will be poor, causing air bubbles to remain in the slurry, and conversely, if the viscosity is too low, the metal powder will dissolve in the binder solution. It is not stably and uniformly dispersed in the liquid. In addition, if the slurry applied to the metal powder binder solution remains fluid for a long time after being applied onto the wire mesh, there is a risk that it will flow out from the wire mesh. It must be able to solidify. From this point of view, in the method of the present invention, a binder solution prepared by dissolving an organic binder in a mixed solvent containing an organic solvent is used as the binder solution. When this solution is used, the slurry has appropriate fluidity when it is applied to the wire mesh, and after the slurry is applied and supported on the wire mesh, the solvent quickly evaporates and the slurry solidifies. There is no risk of deformation.

The drying rate of the slurry can also be adjusted by using a solvent obtained by mixing water and an organic solvent in a required ratio as a mixed solvent.

As the organic binder, methyllerulose is preferably used, but it is not limited thereto.

It is also possible to arrange Sea 1~ on the lower surface of the wire mesh and apply the slurry to the upper surface of the wire mesh. In this case, the slurry is prevented from flowing out from the underside of the wire mesh. If a sheet with good liquid absorbency, such as filter paper, is used as the sheet, the solvent in the slurry will be absorbed by the sheet, and the drying of the slurry will be further accelerated.

Calcining is preferably carried out in a reducing atmosphere.

In manufacturing the electrode according to the present invention, the slurry carrying device used directly in the slurry carrying step includes a wire mesh pulling means for moving the wire mesh in a desired direction along the base, and a slurry for applying slurry to the top surface of the moving wire mesh. It consists of a coating means.

The slurry application means preferably comprises a hopper having a width-adjustable slurry outlet slit 1 between the soil surface of the wire mesh.

On the downstream side of the slurry application means, a slurry shaping member is installed, if necessary, to form a coating film repairing sleeve 1 whose width can be adjusted freely between the slurry shaping member and the upper surface of the wire mesh. The same part is particularly useful when obtaining a platform where air bubbles are mixed in the slurry discharged from the small brim or when obtaining a porous plate with a large area.

According to the present invention, an electrode for a molten carbonate fuel cell made of a porous plate having a reinforcing wire mesh on only one side can be made by a simple operation. It is possible to build J. Therefore, by Md-ing the thus obtained electrode so that the wire mesh is on the opposite side of the interface between the electrode and the electrolyte, it is possible to prevent corrosion of the wire mesh by eliminating contact between the wire mesh and the molten carbon M salt. Thus, the melting 1:AM salt fuel F according to this invention
By using the No. 11 battery electrode, the life of the battery can be significantly extended.

EXAMPLES Next, examples of the present invention will be given to demonstrate the above effects.

Example 1 In FIG. 1, the slurry carrying device is made of stainless steel (
A 120-mesh wire mesh (1) made of SUS316) is placed on the base (2) along with filter paper (6) stacked on the underside of the wire mesh (1).
) consists of a wire mesh traction means that moves at a constant speed to the left by a traction motor (3), and a slurry application means that applies slurry (S) to the top surface of the moving wire mesh (1). The slurry application means consists of a hopper (5) equipped with a movable wall (4) for adjusting the slurry application thickness. Then, by setting the height of the movable wall (4), the height of the movable wall (4) is set.
) The width of the slurry outlet loss slit (7) is adjusted.

The following operations were performed on the slurry supporting device having the above configuration. 15 Q of water, 150 Q of methyl alcohol, 0.30 Q of isopropyl alcohol, and 0.0 Q of nonionic surfactant.
2 g of methylcellulose was dissolved in a mixed solvent consisting of 10, and the resulting binder solution and nickel powder (model 123, manufactured by Inco Inc.) 1000 were stirred and kneaded under reduced pressure to form a slurry.

The obtained slurry (S) is put into the popper (5) of the slurry supporting device, and the wire mesh (1) and filter paper (6) are placed on the base (2).
The traction motor (3) moves along the top at a speed of 15 cm/min, and the movable wall (4) is adjusted to move the popper (5
), the width of the slurry outlet slit (7) was Q, 4 mm, and the slurry (S) was applied to the top surface of the wire mesh (1).

After removing the wire mesh (1) supporting the slurry (S) from the slurry supporting device and drying the slurry, the filter paper (6) is peeled off from the wire mesh (1), and then the wire mesh (1) is placed in an electric furnace. After the air in the furnace was replaced with hydrogen, the slurry (S) was held at a temperature of 400° C. for 1 hour and at 950° C. for 1 hour in a hydrogen stream, and the slurry (S) was fired to make it porous.

The electrode made of the porous plate thus obtained has a porosity of 60%.
It had a thickness of 0.35 ml and had a reinforcing wire mesh on only one side, as shown in the micrograph shown in FIG.

Example 2 In FIG. 3, a slurry shaping member (8) consisting of a movable wall for coating is provided on the downstream side of the hopper (5) of the same slurry carrying device as used in Example 1, By setting the height, the width of the coating film repair slit (9) between -L and wire mesh (1) is adjusted.

The following operations were performed on the slurry supporting device having the above configuration. 14q1 of water, 120% of methylal]-al, 0.30% of isopropyl alcohol, and 0.0% of nonionic surfactant.
1.5 g of methyl cellulose was dissolved in a mixed solvent consisting of 10%, and the resulting binder solution and nickel-based alloy powder were mixed with 90% by weight of nickel - 10% of chromium, particle size 5 to 30%.
III) 100q was stirred and kneaded under reduced pressure to form the powder into a slurry.

The obtained slurry (S) is put into the hopper (5) of the slurry carrying device, and the wire mesh (1) and filter paper (6) are placed on the base (2).
i 5 cn+/mi with traction motor (3) along the top
Move at a speed of n, adjust the movable wall (4) by setting the width of the slurry output of the revolving tube (5) to Q,
9+++n+ binding, set the width of paint film repair slit 1-(9) to 0
．． 8n+m, and the slurry (S) was applied to the top surface of the wire mesh (1).

After removing the wire mesh (1) supporting the slurry (S) from the slurry supporting device to avoid drying the slurry, the filter paper (6) is peeled off from the wire mesh (1), and then the wire mesh (1) is placed in an electric furnace. After replacing the air in the furnace with hydrogen, the slurry (S) was held in a hydrogen stream at a temperature of 400°C for 1 hour and at 1000°C for 12 hours, and the slurry (S) was fired to make it porous.
.

The electrode made of the porous plate thus prepared has a porosity of 58
% rice thickness Q was 3 mm, and the cross-section observed through a microscopic photograph showed that it also had a reinforcing wire mesh on only one side.

[Brief explanation of the drawing]

Figures 1 and 3 are vertical cross-sectional views showing the slurry supporting devices used in Examples 1 and 2, respectively, and Figure 2 is a micrograph showing the particle structure of the porous plate obtained in Example 1. (Magnification: 60 times). (1)...wire mesh, (2)...base, (3)...traction motor, (4)...movable wall, (5)...hopper, (6)...filter paper , (7)...slit, (8)
...Slurry shaping member, (9)...Suritsu I~, (
S)...Slurry. ``2''

Claims (6)

[Claims] (1) Dissolve an organic binder in a mixed solvent containing an organic solvent, knead the obtained binder solution and metal powder to form a slurry, apply the obtained slurry to one side of a reinforcing wire mesh to support it, and make a supported slurry. 1. An electrode for a molten carbonate fuel cell, characterized in that the porous plate is manufactured by firing a porous body into a plate-like porous body, and has a wire mesh on only one side. (2) Adjusting the drying speed of the slurry by using a solvent made by mixing water and an organic solvent in a required ratio as a mixed solvent.
An electrode according to claim 1. (3) The electrode according to claim 1 or 2, wherein methylcellulose is used as the organic binder. (4) The electrode according to any one of claims 1 to 3, wherein sheets are stacked and arranged on the lower surface of the wire mesh, and the slurry is applied to the upper surface of the wire mesh. (5) The electrode according to claim 4, wherein a sheet having good liquid absorption properties is used. (6) Claim 1, in which the firing is performed in a reducing atmosphere.
The electrode according to any one of items 1 to 5.