JPS62278762A - Manufacture of electrolyte plate for molten carbonate fuel cell - Google Patents

Abstract

PURPOSE:To increase the uniformity and strength of an electrolyte plate by molding a paste-like mixture comprising electrolyte retaining material and binder with a roller, folding back the molding via a mat made of ceramic fibers, and molding several times with the roller. CONSTITUTION:A paste-like mixture obtained by kneading slurry comprising electrolyte retaining material powder and organic solvent together with an organic binder, is molded in a plate with a roller 6 to form a mother material 7. A short fiber mat 9 obtained by intertwining ceramic fibers in a felt shape is placed on the half of one side of the mother material 7, and the mother material 7 is folded back so that the mat 9 is interposed. The mather material 7 and the mat 9 are rolled several times to form an electrolyte plate for a molten carbonate fuel cell. Since the ceramic fibers serving as reinforcing material are uniformly distributed, the electrolyte plate having uniformity and large strength can be obtained.

Description

[Detailed description of the invention] 3. Detailed description of the invention [Technical field to which the invention pertains] This invention provides a molten carbonate fuel 1! This article relates to a farming method using electrolyte plates for the bottom of ponds.

[Prior art and its problems]

The general configuration of the group battery is shown in Figure 3. That is, a molten carbonate fuel cell includes an electrolyte plate 1 that holds an electrolyte, an anode electrode 2 and a cathode electrode 3 that sandwich the electrolyte plate 1 and face each other on both sides, and surround each electrode 2.3 from the outside. The cell frame 4 and the electrode support plate 5, which also serves as a current collector plate, are interposed between the cell frame 4 and each of the electrodes 2.3.

Here, the electrolyte plate 1 is lithium carbonate (LI) as an electrolyte.
2CO3) and potassium carbonate (K2CO3) are held inside an electrolyte holding material such as lithium aluminate or magnesia.

On the other hand, as a manufacturing method for the electrolyte plate described above, the hot press method in which a paste mixture of carbonate and an electrolyte holding material is kneaded is injected into an electrolyte plate mold of a predetermined shape, and the mold is deformed by applying heat. Although it is generally widely adopted, this hot pressing method has drawbacks such as a long production time, low production efficiency, and difficulty in making the electrolyte plate thinner. Instead, recently, a method for producing electrolyte plates using a roll forming method has been developed and put into practice in some areas. This roll-forming method involves kneading the electrolytic side holding material and a binder, rolling the paste-like mixture to a predetermined thickness using roll-forming l, cutting it to a predetermined size, shaping it, and baking it to form an electrolyte. This is a back-door method to obtain a plate, and the carbonate as an electrolyte is either kneaded in advance with an electrolyte holding material or a binder and impregnated into the plate, or it is rolled and baked to form a paste mixture to form a solid. After removing the adhesive, it is held on the electrolyte plate by melt impregnation.

By the way, as described above, the mixture of the electrolyte holding material and the binder is rolled and formed as it is by the roll forming method,
The mechanical strength of the electrolyte plate is very weak, and for this reason conventionally the electrolyte plate is made by mixing short ceramic fibers that are resistant to corrosion against molten carbonate into the paste-like mixture and then roll-forming the mixture. Attempts are being made to improve the strength. As is well-known, the reinforcing method by mixing short fibers of ceramic and porcelain mentioned above is effective at increasing electrical resistance due to the interfacial bonding force of the short fibers.
This is expected to have a reinforcing effect on the quality board. However, when carrying out the lever reinforcement method, if short fibers with an aspect ratio (fiber length/fiber diameter) of the ceramic fibers described above exceed 200 are used, the short fibers are mixed into the electrolyte holding material and kneaded. In the process, a phenomenon occurs in which the fibers become entangled with each other in the shape of a ball, making it extremely difficult to disperse the fibers over the entire surface of the electrolyte holding material. On the other hand, in order to further increase the strength of the electrolyte plate using the reinforcement method described above, it is necessary to increase the volume content of fibers mixed in the electrolyte holding material. When mixed in the electrolyte holding material, it becomes even more difficult to obtain uniform dispersion of fibers using conventional methods.
Due to the dense entanglement of the fibers, it becomes increasingly difficult to obtain a good interfacial bonding state at the fiber interface, and as a result, it is almost impossible to produce a homogeneous and strong electrolyte plate.

[Purpose of the invention]

This invention has been made in consideration of the above points, and uses a roll forming method (γ) to produce an electrolyte-retaining material and a binding material using corrosion-resistant short fibers pre-pressed with a square root. When mixing in the mixture to strengthen the electrolyte plate,
To provide a spreading method for obtaining an electrolyte plate with high mechanical strength, in which fibers are uniformly dispersed over the entire area within a layer of a base material, and a good interfacial bonding state of the fibers is obtained. With the goal.

[Key points of the invention]

In order to achieve the above object, the present invention uses a plate-shaped molded body obtained by roll-forming a paste mixture of an electrolyte holding material and a binder into a plate shape as a base material, and half of the base material is used as a base material. The roll rolling process of folding back and forming a Prt plate into a roll was repeated several times, and at each folding process of the base material, a mat of ceramic fiber was interposed as a reinforcing material between the folded parts of the base material. By doing this, the ceramic fibers are uniformly dispersed within the layer of the base material, and at the same time, the base material bites into the gaps between the fibers and binds together, resulting in a good interfacial bonding state. You'll be able to do it :) It's more than that.

[Embodiments of the invention]

FIG. 1 is a manufacturing process diagram of an electrolyte plate according to an embodiment of the present invention, and FIG. 2 is a diagram showing the shape of a felt-like ceramic fiber mat used in the process shown in FIG. In FIG. 1, steps (3) to 11 (hl represents the manufacturing process) are shown sequentially.

Among the above manufacturing steps, 8g1 in Figure 1al is made by slurrying the electrolyte retaining material powder as lithium aluminate with an organic solvent, further adding an organic binder, and kneading the resulting paste-like mixture to a thin layer using a rolling roller indicated by reference numeral 6. A base material 7 that has been rolled and formed into a plate shape is shown. Here, as shown in FIG. 2, an extremely thin fiber mat 9 made of ceramic short fibers 8 such as alumina and the short fibers 8 intertwined in a felt-like manner is separately prepared as a reinforcing material. A piece of base material 7 (Ill
Overlap in half the area. Next, as shown in the same figure (cl), the base material 7 is folded in half in the longitudinal direction as shown by arrow P, and the fiber mat 9 is sandwiched inside the base material 7.This folded state is shown in +dl in the same figure. As shown, in this state, the planar area of the base material 7 is the same as the original area.Next, the direction of the base material 7, which was folded in half in the previous step, is varied in the plane direction as shown by the arrow Q. After the conversion, as shown in tel in the same figure, it is rolled again with roller 6 and spread again thinly to the original area shown in 1al in the same figure.In this state, there is a gap between the base material 70 in the process in cl. As the interposed fiber mat 9 spreads the base material by roll rolling, the short fibers 8 (second [!82I) of the felt-like fiber mat 9 are spread as if unraveled and dispersed over the entire area within the layer of the base material. After that, a fiber mat 9 with an area of % is placed on one half of one side of the base material 7 as shown in the same figure (g+, (hl)), and
The sheets are folded in half and stacked one on top of the other, and then their orientation is changed (a) degree in the surface direction and rolled again using rollers 6.

Thereafter, the base material 7 is folded back in the same manner as for making a pie crust, and each time a new fiber mat 9 is inserted between the folded portions of the base material 7, and the operation of roll forming is repeated several times. In the layer 7, the alumina short fibers 8 are evenly dispersed and encapsulated in a two-dimensional direction, alternating each other in multiple J- shapes. Moreover, the base material bites into the gaps in the fiber mat 9 that have expanded due to the roll rolling in each of the above steps, and is bound together.
As a result, the interfacial bonding state of the fibers also becomes good. Finally, the base material 7 is cut, shaped into a predetermined electrolyte plate size, and the plate is fired to remove the binder, and then melted and impregnated with carbonate to obtain an electrolyte plate. The electrolyte plate manufactured in this way has a high fiber volume content, and the fibers are uniformly dispersed within the base material layer without sacrificing the degree of dispersion, and the interfacial bonding state of the fibers is also good. It has been confirmed from the results of the Inspection 1 strength test of the inventor's product that it is homogeneous throughout and exhibits high mechanical strength. In particular, as mentioned above, by changing the orientation of the base material (a) degree in the plane direction each time roll forming is performed, the fiber mat can be produced in two-dimensional directions without being biased to one side within the base material layer. It becomes possible to spread it evenly over the entire area. In addition, in the above example, the carbonate is held in the electrolyte plate by baking the roll-formed paste mixture to remove the binder and then melting and impregnating the carbonate as the electrolyte. However, the great invention is not limited to this, and the carbonate is kneaded in advance with an electrolyte holding material and a binder to form a paste-like mixture,
A similar effect can be obtained by impregnating the plate with an electrolyte before molding. In this case, the paste-like mixture is roll-formed while containing the electrolyte, and the plate is already impregnated by the time when the binder is burnt out and vaporized by firing.

〔Effect of the invention〕

As described above, according to the present invention, a plate-shaped molded body obtained by roll-forming a paste mixture of an electrolyte holding material and a binder into a plate shape is used as a base material, and half of the base material is The roll rolling process of folding back the base material and roll-forming it into a plate shape is repeated several times, and at each folding process of the base material, a matrix of ceramic fibers is used as a reinforcing material between the folded parts of the base material.

By performing roll forming with a reinforcing material, corrosion-resistant ceramic fibers can be easily dispersed and encapsulated in multiple layers of the base material evenly. As a result, it is possible to simultaneously obtain a high fiber content while maintaining a uniform dispersion of fibers, and a good interfacial bonding state of the fibers.As a result, the electrolyte plate can be used as a homogeneous and mechanically strong electrolyte plate for molten carbonate fuel cells. A board can be built.

[Brief explanation of the drawing]

Fig. 1 is a diagram of the manufacturing process of an electrolyte plate according to the present invention, and Fig. 2 shows the ceramic interposed in the base material in the process shown in Fig. wC1. FIG. 3 is a cross-sectional view of a unit cell of a molten carbonate fuel cell. In the figure, 1: Electrolyte plate, 6: Rolling roller, 7: Roll-bottomed base material, 8: Ceramic short fibers, 9: Felt-like fiber mat, P: Folding direction of base material, Q: Base material direction of change of direction. 72 illustrations, 3 prisoners

Claims (1)

[Scope of Claims] 1) An electrolyte plate manufacturing method in which an electrolyte plate is manufactured by roll-forming and sintering a paste-like mixture containing an electrolyte holding material and a binder, comprising: roll-forming the mixture into a plate shape; The obtained plate-shaped molded body is used as a base material, and the roll rolling process of folding the base material in half and roll-forming it into a plate shape is repeated several times, and at each folding process of the base material, between the folded parts of the base material 1. A method for manufacturing an electrolyte plate for a molten carbonate fuel cell, which comprises inserting a ceramic fiber mat as a reinforcing material and performing roll forming. 2) The method for producing an electrolyte plate according to claim 1, wherein the molten carbonate fuel is characterized in that carbonate as an electrolyte is kneaded in advance with an electrolyte holding material and a binder to form a paste mixture. A method for manufacturing electrolyte plates for batteries. 3) In the method for manufacturing an electrolyte plate according to claim 1, the roll-formed paste mixture is fired to remove the binder, and then a carbonate as an electrolyte is melted and impregnated. A method for manufacturing an electrolyte plate for a carbonate fuel cell. 4) The method for manufacturing an electrolyte plate according to claim 1, characterized in that each time the base material is folded back during the roll rolling process, its direction is changed by 90 degrees in the plane direction and roll forming is performed again. A method for manufacturing an electrolyte plate for a molten carbonate fuel cell. 5) An electrolyte plate manufacturing method for a molten carbonate fuel cell according to claim 1, wherein the ceramic fiber mat is a fiber mat in which short ceramic fibers are intertwined in a felt-like manner. Production method.