JPH065305A - Molten carbonate fuel cell - Google Patents

Abstract

PURPOSE:To provide a molten carbonate fuel cell in which deterioration of performance of a fuel cell can be prevented, and in which seal performance can be improved by improving a seal body itself for reducing electrolyte movement quantity in the seal body. CONSTITUTION:A molten carbonate fuel cell is composed of a fuel cell lamination body comprising unit cells and separators laminated on each other in order, and manifolds applied to side surfaces of it through seal bodies. The seal body 5 is composed of ceramic fiber 20 and hole-sealing material 21 carried by them. The hole-sealing material 21 is not good electric conductive material, but its volume is expanded by chemical reaction with molten carbonate electrolyte or material generated from the molten carbonate electrolyte, and its reaction product by chemical reaction with the molten carbonate electrolyte or material generated by the molten carbonate electrolyte is not good electric conductive material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molten carbonate fuel cell, and more particularly to a laminated structure of a molten carbonate fuel cell which delays an electrolyte migration speed and improves a gas sealing function.

[0002]

2. Description of the Related Art FIG. 5 is a partially cutaway perspective view of a laminated body of a conventional molten carbonate fuel cell, in which 1 is a single cell, 2 is a surface of the laminated body on the fuel inlet side, and 3 is an oxidant gas. The inlet side laminate surface, 5 is a porous seal body for mounting a manifold (not shown), 11 is an anode end plate,
12 is a cathode end plate.

Here, in the unit cell 1, an anode electrode made of porous sintered nickel-aluminum and a cathode electrode made of porous nickel oxide are arranged on the main surface of a porous electrolyte matrix. Lithium (L
A matrix of iAlO ₂ ) or other inert ceramic is filled with a molten alkali metal carbonate type electrolyte (eg Li ₂ CO ₃ / K ₂ CO ₃ ), and the anode reaction gas flow path is on the back of the anode electrode. A cathode reaction gas channel is provided on the back surface of the cathode electrode. Further, in the laminated body of the molten carbonate fuel cell, the unit cell 1 is laminated in several tens to several hundreds between the anode end plate 11 and the cathode end plate 12, and the surface of the laminated body on the fuel inlet and outlet sides, the oxidant gas A manifold is attached to each of the inlet-side and outlet-side surfaces of the laminate through a seal body 5.

Next, the operation of the above conventional molten carbonate fuel cell will be described. When the temperature of the fuel cell is raised to the operating temperature, the electrolyte charged in the unit cell 1 is melted and absorbed by the anode electrode, the cathode electrode and the matrix in the unit cell 1, and is in contact with the side surface of the cell.
Is also absorbed. At this time, gas sealing between the laminate surface and the manifold is performed by wet sealing with an electrolyte. When the fuel cell in this state is operated, the electrolyte in the seal body 5 causes an ionic short circuit from the cathode end plate 12 side to the anode end plate 11 side, and the cathode end plate 12 side to the anode end plate is caused by an electric force. 1
Moving toward the 1st side, the electrolyte is flooded in the anode end cell, while the electrolyte is depleted in the cathode end cell.

However, due to the electrolyte flooding and depletion caused by the migration of the electrolyte, the performance of the battery is significantly impaired and the operation of the laminate is also impaired.

[0006] As a remedy for this, a laminated structure for delaying the effect of electrolyte migration is provided by providing a porous storage layer for storing an electrolyte on the anode end plate 11 and the cathode end plate 12 (JP-A-63-279575). Alternatively, a laminated body structure that forms a complete gas seal body with low melting point crystallized glass and prevents the electrolyte migration through the seal body (JP-A-63-165).
No. 75) is proposed.

[0007]

Since the conventional molten carbonate fuel cell is constructed as described above, the electrolyte in the seal body 5 moves from the cathode end plate 12 side to the anode end during operation of the fuel cell. There was a problem that the performance of the battery was significantly impaired by the movement and the exhaustion of the electrolyte caused by the movement of the electrolyte toward the plate 11 side, and the operation of the laminate was also hindered.

Further, the anode end plate 11 and the cathode end plate 1
In the fuel cell stack as an improvement measure in which a porous storage layer for storing an electrolyte is provided in 2 and, since the allowable amount of electrolyte change of the end cells is increased, the amount of electrolyte change that occurs through the seal body 5 is constant. In some cases the effect of electrolyte migration can be delayed, but it is not a fundamental solution as electrolyte migration is still occurring. Moreover, the movement of the electrolyte through the sealing body 5 is caused by the electric force of the cathode end plate 1.
In addition to the movement from the 2 side to the anode end plate 11 side, there is a movement in the direction in which the electrolyte content is made uniform by the capillary force, and normally, the total movement amount works by acting in the opposite direction of the movement by the electric force. Although it is decreasing, when the storage capacity of the end cells is increased, the total transfer amount increases due to the balance of the capillary force between the cells with increased storage capacity and the cells that do not, and the effect of the transfer is not delayed. There was also the problem of shortening the service life.

Further, in the fuel cell stack as an improvement measure in which the sealing body 5 is a low melting point crystallized glass, the electrolyte is consumed even in the unit cell 1 due to corrosion, evaporation, etc., and the electrolyte in each cell is reduced. Therefore, there is also a problem that performance deterioration due to electrolyte depletion occurs in each cell as the operation is continued. Therefore, it is conceivable to replenish the electrolyte in each battery, but only the end cells can be replenished during operation, and in order to uniformly replenish all cells, it was necessary to stop the operation and lower it to room temperature. .

The present invention has been made to solve the above problems, and improves the seal body itself to reduce the amount of movement of electrolyte in the seal body and prevent the performance of the fuel cell from being deteriorated. Moreover, it is a first object to obtain a molten carbonate fuel cell with improved sealing performance.

Further, the sealing body itself is improved so that the electric conductivity of the sealing body is changed in the direction of the stack so that the electrolyte added to the end cells can be uniformly distributed in each cell of the stack without stopping the operation. A second object of the present invention is to obtain a molten carbonate fuel cell that prevents deterioration of the performance of the fuel cell and improves the operating rate.

[0012]

The molten carbonate fuel cell according to the first aspect of the present invention is not a good electric conductor, but a molten carbonate type electrolyte or a chemical reaction with a substance produced from the molten carbonate type electrolyte. Then, the sealing material whose volume expands and whose reaction product by the chemical reaction with the molten carbonate type electrolyte or the substance generated from the molten carbonate type electrolyte is not a good electric conductor is placed on the ceramic fiber cloth or felt. The carrier is carried to form a seal body.

Further, the molten carbonate fuel cell according to the second aspect of the present invention is not a good electric conductor, but a reaction produced by a chemical reaction with a molten carbonate electrolyte or a substance produced from the molten carbonate electrolyte. The material is not a good electric conductor, and the sealing material that reacts preferentially with one of the main metal ions of the molten carbonate type electrolyte is carried on the cloth or felt of ceramic fiber to form a sheet. It is composed.

In the molten carbonate fuel cell according to the third aspect of the present invention, a sealing material is formed by supporting a sealing material made of simple carbonate on a cloth or felt of ceramic fiber. is there.

Also, in the molten carbonate fuel cell according to the fourth aspect of the present invention, the cross-sectional area of the seal body in the direction perpendicular to the stacking direction of the fuel cell stack is large on the cathode end plate side and is large on the anode end plate side. It is configured to be smaller on the side.

The molten carbonate fuel cell according to the fifth aspect of the present invention is configured such that the porosity of the seal body is large on the cathode end plate side and small on the anode end plate side. is there.

[0017]

According to the first aspect of the present invention, the sealing material in the seal body melts into the seal body through the matrix when the temperature of the fuel cell stack is raised for operation. It reacts with the carbonate type electrolyte to produce a reaction product. This means that the volume of the sealing material has substantially expanded due to the reaction with the electrolyte, and the unreacted sealing material and the reaction product block the pores of the ceramic fiber cloth or felt of the seal body. , The gas seal function is enhanced. Also, the pore volume in the seal body is reduced by being blocked by the sealing material and the reaction product which are not good electrical conductors, and the ionic conductivity (electrical conductivity) of the electrolyte from the cathode end plate to the anode end plate is lowered, The amount of electrolyte migration from the cathode end plate to the anode end plate is reduced.

In the second invention of the present invention,
The sealing material in the seal body reacts preferentially with one of the main metal ions of the molten electrolyte that enters through the matrix, thereby changing the electrolyte composition in the seal body and increasing the melting point. As a result, the electrolyte is solidified in the seal body, the pores of the seal body are closed, the gas sealing function is enhanced, the electric conductivity is lowered, and the amount of movement of the electrolyte is reduced.

According to the third aspect of the present invention,
The sealing material in the sealing body does not chemically react with the molten electrolyte that enters through the matrix, but it dissolves in the electrolyte, or the electrolyte gradually dissolves into the sealing material, gradually melting the melting point of the electrolyte in the sealing body. Rises and solidifies to close the pores of the seal body, which enhances the gas sealing function, lowers the electrical conductivity, and reduces the amount of movement of the electrolyte.

In the fourth invention of the present invention,
Since the cross-sectional area of the seal body in the direction perpendicular to the stacking direction of the fuel cell stack is large on the cathode end plate side and small on the anode end plate side, the electrical conductivity of the seal body changes in the stacking direction. The electrolyte added to the end cells is evenly distributed to each cell of the stack without stopping the operation, which prevents the performance of the fuel cell from being deteriorated and improves the operating rate.

In the fifth aspect of the present invention,
Since the porosity of the seal body in the direction perpendicular to the stacking direction of the fuel cell stack is large on the cathode end plate side and small on the anode end plate side, the electrical conductivity of the seal body changes in the stacking direction. Then, without stopping the operation, the electrolyte added to the end cells is uniformly distributed in each cell of the stack, which prevents the performance of the fuel cell from being deteriorated and improves the operating rate.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. Example 1. The first embodiment is an embodiment according to the first invention of the present invention. 1 is an enlarged schematic cross-sectional view of a sealing body in a molten carbonate fuel cell showing a first embodiment of the present invention, and FIG. 2 is a sealing body and a laminated body in a molten carbonate fuel cell showing the first embodiment of the present invention. 6 is a partial cross-sectional view of the connecting portion of FIG. 5, in which the same or corresponding portions as those of the conventional molten carbonate fuel cell shown in FIG. In the figure, 20 is a ceramic fiber constituting the seal body 5, 21 is a sealing material, 22 is an anode electrode, 23 is a cathode electrode, and 24 is a matrix.

Here, the seal body 5 is the ceramic fiber 20.
The sealing material 21 is carried in the inside. In addition, there are various methods for impregnating the ceramic fibers 20, but in consideration of the ease of handling the seal body 5 after impregnation, the above powder is added to a solution containing an organic binder and a plasticizer. It is desirable that the above is turbid and impregnated.

Next, the operation of the first embodiment will be described. When the temperature is raised to operate the fuel cell stack using the seal body 5 in which the sealing material 21 is carried in the ceramic fiber 20, the electrolyte charged in each cell 1 is melted, and the inside of the cell 1 is melted. Anode electrode 22 and cathode electrode 23 of
And absorbed into the matrix 24. Here, since the matrix 24 and the seal body 5 are in contact with each other, the electrolyte also enters the seal body 5. The electrolyte that has entered the sealing body 5 comes into contact with the sealing material 21 and reacts to generate a product.

If, for example, ZrO ₂ is used as the sealing material 21, the following reaction will occur. ZrO ₂ + K ₂ CO ₃ → K ₂ ZrO ₃ + CO ₂ ↑ Therefore, K ₂ ZrO _{3 is} contained in the pores of the ceramic fiber 20.
Therefore, unreacted ZrO ₂ and the reaction product K ₂ ZrO ₃ exist so as to close the pores. This means that the sealing material 21 is substantially expanded, and the pore volume of the seal body 5 is reduced.

Further, Z that closes the holes in the seal body 5
Since rO ₂ and K ₂ ZrO ₃ are not good electrical conductors and have a reduced pore volume, the ionic conductivity of the electrolyte from the cathode end plate 12 to the anode end plate 11 is reduced, and the cathode end plate due to an electric force is reduced. The amount of movement of the electrolyte from the 12 side toward the anode end plate 11 side is reduced.

As described above, according to the first embodiment, since the sealing material 21 is carried in the ceramic fibers 20 of the seal body 5, when the molten electrolyte enters the seal body 5, the seal material is sealed. By reacting with 21, the sealing material is substantially expanded, the pore volume of the seal body 5 can be reduced, the gas permeability is lowered, and the gas sealability can be improved. Further, the sealing material 2
1 and the reaction products (ZrO ₂ and K ₂ ZrO ₃ ) are not good electric conductors, the electric conductivity in the seal body 5 is lowered, and the amount of movement of the electrolyte due to an electric force is reduced. Depletion can be suppressed and deterioration of battery performance can be prevented.

In the first embodiment, ZrO ₂ is used as the sealing material 21, but the sealing material 21
As for, as long as it is a substance that expands in volume by chemically reacting with an electrolyte or a substance generated from the electrolyte, is not a good electric conductor itself, and the reaction product generated by the reaction is also not a good electric conductor, for example, MoO ₃ ,
Use of oxides and nitride powders of group IV, group VA, group VI and group VIIA having an atomic number of 22 or more, such as WO ₃ , ZrO ₂ and GeO ₂ , or nitrides or silicon nitrides of group IIIB of the periodic table. You can

Example 2. The second embodiment is an embodiment according to the second invention of the present invention. In Example 2, using a eutectic salt molar ratio 62:38 with Li ₂ CO ₃ and K ₂ CO ₃ as a molten carbonate electrolyte, K ₂ as sealing material 21
A TiO ₂ powder that reacts preferentially with CO ₃ is used and is carried in the seal body 5 in the same manner as in Example 1 above.

Next, the operation of the second embodiment will be described. When the temperature is raised to operate the fuel cell stack, the electrolyte charged in each unit cell 1 is melted and absorbed in the anode electrode 22, the cathode electrode 23 and the matrix 24 in the unit cell 1. Further, the electrolyte enters the seal body 5 through the matrix 24. The electrolyte that has entered the sealing body 5 comes into contact with the sealing material 21 and produces a product by the following reaction. 2TiO ₂ + K ₂ CO ₃ → K ₂ Ti ₂ O ₅ + CO ₂ ↑

At this time, the TiO used as the sealing material 21
_{Since 2} reacts preferentially with K ₂ CO ₃ , which is one of the components in the electrolyte, the electrolyte in the seal body 5 has a high Li ₂ CO ₃ ratio. Assuming that all of the TiO _{2 of the} sealing material 21 has reacted, the composition of the electrolyte in the sealing body 5 is Li ₂ CO ₃
Exceeds 90% by molar ratio, and the melting point is 70
It becomes 0 ° C. or higher and solidifies at 650 ° C. which is a normal operating temperature. Therefore, the electrolyte solidifies in the pores of the ceramic fiber 20 and TiO ₂ and K ₂ Ti ₂ O ₅ are present, so that the pore volume of the seal body 5 is reduced.

Further, the T that closes the holes in the seal body 5
Since iO ₂ and K ₂ Ti ₂ O ₅ are not good electrical conductors and have a reduced void volume, the ionic conductivity of the electrolyte from the cathode end plate 12 to the anode end plate 11 is reduced, and the cathode due to electric force is used. The amount of movement of the electrolyte from the end plate 12 side toward the anode end plate 11 side is reduced.

As described above, according to the second embodiment, Li ₂
When a eutectic salt of CO ₃ and K ₂ CO ₃ is used as the electrolyte, the ceramic fiber 20 of the sealing body 5 is sealed with TiO ₂ which preferentially reacts with K ₂ CO ₃ which is one component of the electrolyte. Since it is used as the pore material 21, when the melted electrolyte enters the seal body 5, K ₂ CO ₃ reacts with TiO ₂ to make the electrolyte composition rich in Li ₂ CO ₃ and raise the melting point. The solidification of the electrolyte is caused in the seal body 5, the pore volume of the seal body 5 can be reduced, the gas permeability is lowered, and the gas sealability can be improved. Furthermore, the sealing material 21, the reaction products (TiO ₂ and K ₂ Ti ₂ O ₅ ), Li ₂ C
O ₃ and K ₂ CO ₃ are not good electric conductors, the electric conductivity in the sealing body 5 is lowered, the amount of movement of the electrolyte due to an electric force is reduced, and the electrolyte is prevented from being flooded and depleted due to the movement of the electrolyte. It is possible to prevent performance degradation.

In the second embodiment, as the sealing material 21, TiO ₂ powder which reacts preferentially with K ₂ CO ₃ which is one component of the electrolyte is used. However, in addition to TiO ₂ , MoO is also used. ₃ , WO ₃ , ZrO ₂ or a mixture of two or more thereof can be used.

When zirconia felt is used for the ceramic fibers 20 of the seal body 5, the normal seal body 5 is used.
Since about 10% of the electrolyte is contained with respect to the weight of TiO ₂ , in order to change the composition of this electrolyte, it is desirable that TiO ₂ is supported in a weight ratio of 3% or more with respect to the felt.

Example 3. The third embodiment is another embodiment according to the second invention of the present invention. In the second embodiment,
Although the TiO ₂ powder that preferentially reacts with the electrolyte component K ₂ CO ₃ is used as the sealing material 21, in this Example 3, the GeO ₂ powder that preferentially reacts with the electrolyte component Li ₂ CO ₃ is used. Is used as the sealing material 21,
Has the same effect.

Example 4. The fourth embodiment is an embodiment according to the third invention of the present invention. In Example 4, using eutectic salt molar ratio 62:38 with Li ₂ CO ₃ and K ₂ CO ₃ as a molten carbonate electrolyte, which is one component of the electrolyte component as a sealing material 21 K ₂ CO ₃ was used and carried in the seal body 5 in the same manner as in the above-mentioned Example 1.

Next, the operation of the fourth embodiment will be described. When the temperature is raised to operate the fuel cell stack, the electrolyte charged in each unit cell 1 is melted and absorbed in the anode electrode 22, the cathode electrode 23 and the matrix 24 in the unit cell 1. Further, the electrolyte enters the seal body 5 through the matrix 24. At this time, K ₂ CO ₃ that is the sealing material 21 is dissolved in the electrolyte that has entered the seal body 5, or the electrolyte is the sealing material 21.
The solid solution gradually dissolves in the pores, and the melting point of the electrolyte gradually rises to solidify in the pores.

Therefore, in the pores of the ceramic fiber 20, the electrolyte solidifies and the sealing material 21 exists,
The pore volume of the seal body 5 is reduced.

Further, L which closes the hole in the seal body 5
Since i ₂ CO ₃ and K ₂ CO ₃ are not good electrical conductors and have a reduced pore volume, the ionic conductivity of the electrolyte from the cathode end plate 12 to the anode end plate 11 is reduced, and the cathode due to electric force is used. Anode end plate 1 from the end plate 12 side
The amount of movement of the electrolyte toward the first side is reduced.

As described above, according to the fourth embodiment, Li ₂
When a eutectic salt of CO ₃ and K ₂ CO ₃ is used as an electrolyte, K ₂ CO ₃ (simple carbonate), which is one component of the electrolyte, is contained in the ceramic fiber 20 of the sealing body 5 as a sealing material 21. Therefore, when the molten electrolyte enters the seal body 5, K ₂ CO ₃ dissolves in the electrolyte, the electrolyte composition changes and the melting point rises, and the electrolyte solidifies in the seal body 5. It is possible to reduce the pore volume of the seal body 5,
The gas permeability is lowered and the gas sealing property can be improved. Furthermore, Li ₂ CO ₃ and K ₂ CO ₃ are not good electric conductors, and the electric conductivity in the seal body 5 is reduced, the amount of movement of the electrolyte due to electric force is reduced, and the flooding and depletion of the electrolyte due to the movement of the electrolyte are suppressed. Therefore, it is possible to prevent deterioration of battery performance.

In the fourth embodiment, K ₂ CO ₃ is used as the sealing material 21, but the sealing material 21
The same effect can be obtained by using a simple carbonate as a component of the composition of the molten carbonate type electrolyte or a carbonate of Group IA or IIA of the periodic table.

Example 5. The fifth embodiment is an embodiment according to the fourth invention of the present invention. Example 3 FIG. 3 is a schematic sectional view of a laminated body in a molten carbonate fuel cell showing Example 5 of the present invention.

In the fifth embodiment, the width of the seal body 5 in the stacking direction of the fuel cell stack is narrowed from the cathode end plate 12 side toward the anode end plate 11, that is, the stacking direction of the fuel cell stack is set. On the other hand, the cross-sectional area of the seal body 5 in the vertical direction is configured to decrease from the cathode end plate 12 side toward the anode end plate 11. Here, a stack of 20 cells of the effective area 5000 cm ^2, when the electrical conductivity in a laminate using a felt zirconia fibers of about 0.01~0.1S / cm · Ω, the cathode end plate 1
2 side is 0.07 cm ² , and the anode end plate 11 side is 0.
The effect is high when the difference in cross-sectional area of 02 cm ² is smoothly distributed in the stacking direction.

FIG. 4 is a schematic cross-sectional view for explaining the movement of the electrolyte between the sealing body and the unit cell in the molten carbonate fuel cell according to the fifth embodiment of the present invention, where i is an arbitrary cell number. , T represents the amount of electrolyte flowing from the seal body 5 into the cell, and G represents the electrolytic mass passing through the cross section of the seal body 5 at each cell boundary.

Next, the operation of the fifth embodiment will be described. When the temperature is raised to operate the fuel cell stack, the electrolyte charged in each unit cell 1 melts and enters the seal body 5 via the matrix. At this time, the electrolytic mass in the seal body 5 depends on the electrolytic mass in the adjacent cells, but in Example 5, the content rate is about 10 to 20% of the weight of the seal body 5. When the fuel cell is operated in such a state, the electrolyte in the seal body 5 moves from the cathode end plate 12 side to the anode end plate 11 side by the cell voltage as a driving force.

At this time, the amount of movement G of the electrolyte passing through the boundary of each unit cell 1 is determined by the movement due to the driving force and the backflow due to the capillary force, and is proportional to the sectional area of the seal body 5. Here, A is a cross-sectional area and k is a constant. G = kA (Equation 1) Cell numbers are numbered from the end cell 1 on the cathode end plate 12 side to the end cell 20 on the anode end plate 11 side, and the balance is obtained by the electrolyte transfer amount G and the electrolyte inflow amount from the sealing body 5 to each cell. Then, it is expressed by the following equation. T _i = G _i-1 −G _i (where G ₀ = 0, G ₂₀ = 0) (Equation 2)

Assuming that the cross-sectional area becomes narrower at a rate of ΔA per cell, the above equations (1) and (2) are expressed by the following equations. T _i = kΔA (Equation 3) That is, assuming that the rate of narrowing the cross-sectional area per cell is constant, the electrolyte is evenly distributed to each cell. However, since the electrolyte is only going out from the end cell on the cathode end plate 12 side, it is necessary to replenish the electrolyte at an appropriate time. The replenishment method may be replenishment directly to the cell using a tube or via the seal body 5.

When the change with time of the electrolyte distribution of the fuel cell of this constitution was calculated, it was 1000 in the fuel cell before improvement.
It was found that it was possible to operate for 100,000 hours or more, even though it did not last for 0 hours.

Example 6. The sixth embodiment is an embodiment according to the fifth invention of the present invention. In the fifth embodiment, the cross-sectional area of the seal body 5 in the direction perpendicular to the stacking direction is reduced from the cathode end plate 12 side toward the anode end plate 11 side by changing the width of the seal body 5. In the sixth embodiment, the amount of the sealing material 21 carried is set to the cathode end plate 12
Side to the anode end plate 11 side, the porosity of the seal body 5 is reduced from the cathode end plate 12 side to the anode end plate 11 side, and the same effect is achieved.

[0051]

Since the present invention is constituted as described above, it has the following effects.

The molten carbonate fuel cell according to the first aspect of the present invention expands in volume by chemically reacting with a molten carbonate type electrolyte or a substance produced from the molten carbonate type electrolyte, rather than being a good electric conductor. In addition, the sealing material is carried on the cloth or felt of the ceramic fiber by loading the sealing material whose reaction product by the chemical reaction with the molten carbonate type electrolyte or the substance generated from the molten carbonate type electrolyte is not a good electric conductor. Since it is configured, the sealing material reacts with the electrolyte to substantially expand the volume and close the pores of the seal body, which can enhance the gas sealing function, lower the electric conductivity, and reduce the movement amount of the electrolyte. It can be reduced.

The molten carbonate fuel cell according to the second aspect of the present invention is not a good electric conductor, but a reaction produced by a chemical reaction with a molten carbonate electrolyte or a substance produced from the molten carbonate electrolyte. The material is not a good electric conductor, and the sealing material that reacts preferentially with one of the main metal ions of the molten carbonate type electrolyte is carried on the ceramic fiber cloth or felt to form the seal body. Since it is composed, the sealing material reacts with the specific metal carbonate of the electrolyte component, changing the electrolyte composition, raising the melting point and solidifying, blocking the pores of the sealing body, and enhancing the gas sealing function. In addition, the electric conductivity is lowered and the amount of movement of the electrolyte can be reduced.

Further, in the molten carbonate fuel cell according to the third aspect of the present invention, the sealing material is constituted by supporting the sealing material made of simple carbonate on the cloth or felt of ceramic fiber. Therefore, the mixture of the high melting point that takes in the electrolyte is formed, and the pores are substantially closed in the seal body, so that the gas sealing function can be enhanced, and the electric conductivity is lowered and the movement amount of the electrolyte can be reduced.

Further, in the molten carbonate fuel cell according to the fourth aspect of the present invention, the cross-sectional area of the seal body in the direction perpendicular to the stacking direction of the fuel cell stack is large on the cathode end plate side and the anode end plate. Since it is configured to be small on the side, the electrical conductivity of the seal body changes in the stack direction, the electrolyte added to the end cells without stopping the operation is uniformly distributed in each cell of the stack, Prevents deterioration of fuel cell performance,
Occupancy rate goes up.

Further, the molten carbonate fuel cell according to the fifth aspect of the present invention is configured such that the porosity of the seal body is large on the cathode end plate side and small on the anode end plate side. Therefore, the electric conductivity of the seal changes in the direction of the stack, and the electrolyte added to the end cells is evenly distributed to each cell of the stack without stopping the operation, preventing the performance of the fuel cell from decreasing and operating. The rate goes up.

[Brief description of drawings]

FIG. 1 is an enlarged schematic sectional view of a sealing body in a molten carbonate fuel cell showing Example 1 of the present invention.

FIG. 2 is a partial cross-sectional view of a connecting portion between a seal body and a laminate in the molten carbonate fuel cell showing Example 1 of the present invention.

FIG. 3 is an enlarged schematic sectional view of a laminated body in a molten carbonate fuel cell showing Example 5 of the present invention.

FIG. 4 is a schematic sectional view illustrating movement of an electrolyte between a seal body and a unit cell in a molten carbonate fuel cell according to a fifth embodiment of the present invention.

FIG. 5 is a partially cutaway perspective view of a laminated body of a conventional molten carbonate fuel cell.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cell 5 Seal body 11 Anode end plate 12 Cathode end plate 20 Ceramics fiber 21 Sealing material 22 Anode electrode 23 Cathode electrode 24 Matrix

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] November 2, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0023

[Correction method] Change

[Correction content]

Here, the seal body 5 is the ceramic fiber 20.
The sealing material 21 is carried in the inside. In addition, there are various methods for impregnating the ceramic fibers 20, but in consideration of the ease of handling the seal body 5 after impregnation, the above powder is slurried in a solution containing an organic binder and a plasticizer. It is desirable to make it cloudy and impregnate.

Claims (5)

[Claims] 1. A fuel obtained by sequentially stacking a unit cell including an anode electrode, an anode gas flow path, a cathode electrode, a cathode reaction gas flow path, and a matrix and a separator between an anode end plate and a cathode end plate. A cell stack, a molten carbonate type electrolyte filled in the matrix, and a fuel cell stack are applied to each side of the fuel cell stack via a seal, and a reaction gas is circulated in a gas flow path of each unit cell. In a molten carbonate fuel cell equipped with a manifold,
The seal body is not a good electric conductor, and the volume thereof expands by chemically reacting with the molten carbonate type electrolyte or a substance generated from the molten carbonate type electrolyte, and the molten carbonate type electrolyte or the molten carbonate A molten carbonate fuel cell, characterized in that a sealing material whose reaction product by a chemical reaction with a substance generated from a salt-type electrolyte is not a good electric conductor is carried on a cloth or felt of ceramic fiber. 2. A fuel obtained by sequentially stacking a cell consisting of an anode electrode, an anode gas flow path, a cathode electrode, a cathode reaction gas flow path and a matrix and a separator between an anode end plate and a cathode end plate. A cell stack, a molten carbonate type electrolyte composed of two or more kinds of carbonates filled in the matrix, and a gas of each unit cell, which is applied to each side surface of the fuel cell stack via a seal. In a molten carbonate fuel cell provided with a manifold for circulating a reaction gas in a flow path, the sealing body is not a good electric conductor, and the molten carbonate electrolyte or a substance generated from the molten carbonate electrolyte. A sealing material which is not a good electric conductor and which preferentially reacts with one metal ion of the main metal ions of the molten carbonate type electrolyte. , A molten carbonate fuel cell, characterized in that the molten carbonate fuel cell is constituted by being supported on a cloth or felt of ceramic fiber. 3. A fuel obtained by sequentially stacking a cell consisting of an anode electrode, an anode gas flow path, a cathode electrode, a cathode reaction gas flow path and a matrix and a separator between an anode end plate and a cathode end plate. A cell stack, a molten carbonate type electrolyte filled in the matrix, and a fuel cell stack are applied to each side of the fuel cell stack via a seal, and a reaction gas is circulated in a gas flow path of each unit cell. In a molten carbonate fuel cell equipped with a manifold,
The molten carbonate fuel cell is characterized in that the sealing body is formed by supporting a sealing material made of simple carbonate on a ceramic fiber cloth or felt. 4. A fuel obtained by sequentially stacking a cell consisting of an anode electrode, an anode gas flow path, a cathode electrode, a cathode reaction gas flow path and a matrix and a separator between an anode end plate and a cathode end plate. A cell stack, a molten carbonate type electrolyte filled in the matrix, and a fuel cell stack are applied to each side of the fuel cell stack via a seal, and a reaction gas is circulated in a gas flow path of each unit cell. In a molten carbonate fuel cell equipped with a manifold,
A molten carbonate fuel characterized in that a cross-sectional area of the seal body in a direction perpendicular to the stacking direction of the fuel cell stack is large on the cathode end plate side and small on the anode end plate side. battery. 5. A fuel obtained by sequentially stacking a cell consisting of an anode electrode, an anode gas flow channel, a cathode electrode, a cathode reaction gas flow channel and a matrix and a separator between an anode end plate and a cathode end plate. A cell stack, a molten carbonate type electrolyte filled in the matrix, and a fuel cell stack are applied to each side of the fuel cell stack via a seal, and a reaction gas is circulated in a gas flow path of each unit cell. In a molten carbonate fuel cell equipped with a manifold,
A molten carbonate fuel cell characterized in that the porosity of the sealing body is configured to be large on the cathode end plate side and small on the anode end plate side.