JP2603917B2 - Method for manufacturing electrolyte plate of molten carbonate fuel cell - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement in a method for manufacturing an electrolyte plate of a molten carbonate fuel cell.

[Technical Background of the Invention] A molten carbonate fuel cell is formed by disposing a pair of gas diffusion electrodes opposed to each other, that is, an electrolyte layer holding carbonate as an electrolyte between a fuel electrode and an air electrode. Battery and
Usually, a plurality of the unit batteries are stacked with an interconnector interposed therebetween. In a molten carbonate fuel cell having such a configuration, a fuel gas containing hydrogen and carbon monoxide is supplied to the fuel electrode of the laminate at a high temperature in which carbonate is melted, and a mixed gas containing oxygen and carbon dioxide is supplied to the air electrode. Is operated by flowing each of them.

Usually, an electrolyte plate called an electrolyte tile is used as an electrolyte layer in a molten carbonate fuel cell. Conventionally, this electrolyte tile is prepared by mixing an electrolyte-holding aggregate and a carbonate powder, injecting the mixture into a molding die,
It is manufactured by applying a pressure of 200 to 500 kg / cm ² at ~ 500 ° C.

[Problems of background technology]

However, as described above, the electrolyte tile manufactured using the molding die receives a deformation stress inside the molding die. Specifically, at the time of press molding, the electrolyte tile is subjected to stress and tends to spread in the lateral direction. However, since the electrolyte tile is restrained by the mold, it receives a reaction force from the mold. As described above, since the electrolyte tile receives a reaction force from the mold toward the center from the end face, the electrolyte tile is likely to be cracked during manufacturing. Especially,
As the size of the electrolyte tile increases, the occurrence of cracks becomes significant.
Further, even if no cracking is observed at the time of manufacturing, through cracking is likely to occur due to release of residual stress at the time of manufacturing during storage or power generation test. Furthermore, since the molding die is heavy, it is poor in operability, and it is difficult to mass-produce and enlarge it.

[Object of the invention]

The present invention has been made in order to solve the above-mentioned drawbacks, and it is an object of the present invention to provide a method for producing an electrolyte plate of a molten carbonate fuel cell, which does not crack during production or storage, and can be easily mass-produced and enlarged. It is assumed that.

[Summary of the Invention]

The method for producing an electrolyte plate of a molten carbonate fuel cell according to the present invention comprises forming a clay frame on a lower press plate of a pair of upper and lower carbon press plates, and filling electrolyte powder inside the frame. The hot pressing is directly performed by the pair of press plates.

According to such a method, the clay frame formed on the lower press plate at the time of hot press molding is plastically deformed, so that the force for the electrolyte plate to expand in the lateral direction under stress is made of clay. It can be absorbed by plastic deformation of the frame, and cracks in the electrolyte plate can be reduced.

As the clay constituting the frame having the above-described action, for example, a clay having a sintering temperature of 600 ° C. or more and containing no organic component is desirable.

Further, as the press plate, it is desirable to use a carbon plate having better thermal conductivity than metal. When the carbon plate is used in this manner, the temperature distribution and the applied pressure at the time of high-pressure molding at a high temperature become uniform, and a homogeneous electrolyte plate having less density fluctuation than when a mold is used can be manufactured. Also, since the carbon plate is lighter than the mold,
It is easy to operate and large.

Further, if a carbon plate is used, the heater capacity can be reduced as compared with the mold, and both the heating and cooling times can be shortened. In addition, a plurality of electrolyte plates can be simultaneously hot-pressed by stacking a plurality of press plates each having a clay frame, thereby improving mass productivity.

(Example of the invention)

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Example 1 First, as shown in the figure, a width of 10 mm and a thickness of 10 mm were applied so as to surround a square area of 20 cm square on a 36 cm square carbon plate 1.
A lower press plate 3 having a 9 mm clay frame 2 is prepared, and 200 g of electrolyte powder (LiAlO ₂ : 80 g, Li ₂ CO ₃ : 56 g, K) is placed on a carbon plate 1 surrounded by the clay frame 2. ₂ CO ₃ : 64 g). Next, an upper press plate 4 made of a carbon plate having the same shape as the carbon plate 1 constituting the lower press plate 3 is placed on the powder filling surface, and the powder is sandwiched between the upper and lower press plates 3 and 4 at a high temperature. It was set on the lower heater plate of the pressure device and press-formed at a temperature of 465 ° C. and a pressure of 300 kg / cm ² for 30 minutes.

In this step, the frame 2 made of the electrolyte powder and the clay receives molding stress from the upper and lower press plates 3 and 4. At this time, the electrolyte powder is compressed by receiving compressive stress from the press plate and tends to spread in the lateral direction. The clay frame 2 is also crushed at its upper part and tends to spread in the lateral direction, but also receives a force from the inside to spread the electrolyte powder in the lateral direction. Therefore, the force by which the electrolyte powder tries to spread in the lateral direction can be absorbed by the plastic deformation of the clay frame 2, and cracks in the electrolyte plate can be reduced. In addition, by the mechanism as described above, the force of the clay frame 2 itself trying to spread in the horizontal direction and the force of the electrolyte powder inside it trying to spread in the horizontal direction substantially oppose each other. The dimensions inside the frame 2 do not change much from the dimensions before molding. However, after processing the end face of the electrolyte plate,
Put it to practical use.

By this method, eight out of ten sheets of 20 cm square electrolyte plates without cracks and warpage could be obtained. When the density distribution of the obtained electrolyte plate was measured by an ultrasonic pulse echo method, the density variation within the same electrolyte plate was within 4%. Further, the manufactured electrolyte plate is placed in a vacuum desiccator for 2 minutes.
None of the items stored for weeks exhibited delayed cracking.

Example 2 In the same manner as in Example 1 above, two layers of the lower press plate 3 filled with 200 g of electrolyte powder were stacked, and further placed on the lower heater of the high-temperature pressurizing device with the upper press plate 4 placed thereon. Press molding was performed under the same conditions as in Example 1.

By this method, two electrolyte plates could be manufactured at a time, and 13 out of 16 electrolyte plates of 20 cm square without cracks and warpage could be obtained. When the density distribution of the obtained electrolyte plate was measured by the ultrasonic pulse echo method, the density variation within the same electrolyte plate was within 4.5%.
Furthermore, none of the manufactured electrolyte plates was stored in a vacuum desiccator for 2 weeks, and no delayed cracking occurred.

Comparative Example 200 g of an electrolyte powder was filled into a mold having an inner size of 20 cm, and after uniforming sufficiently, an upper punch was placed, and the mold was placed in the same apparatus as in the first embodiment. ℃,
Press molding was performed under a pressure of 300 kg / cm ² for 30 minutes.

According to such a conventional method, only six sheets out of ten sheets were broken, and a 20 cm square electrolyte plate without warpage could not be obtained. When the density distribution of the obtained electrolyte plate was measured by the ultrasonic pulse echo method, the density fluctuation in the same electrolyte plate was 6%, which was larger than that in the case of the method of the present invention. Further, when the manufactured electrolyte plate was stored in a vacuum desiccator for two weeks, cracks occurred in two of the six plates.

〔The invention's effect〕

As described above in detail, according to the method for producing an electrolyte plate of a molten carbonate fuel cell of the present invention, the occurrence of cracks in the electrolyte plate during production or storage can be reduced, the homogeneity can be improved, and mass production can be achieved. It has a remarkable effect, such as being able to exert its properties.

[Brief description of the drawings]

FIG. 1 is a perspective view of a press plate used in an embodiment of the present invention. 1 ... carbon plate, 2 ... clay frame, 3 ... lower press plate, 4 ... upper press plate.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Akihiko Tsuge 1 Toshiba-cho, Komukai, Sachi-ku, Kawasaki-shi Inside Toshiba Research Institute, Inc. (56) References JP-A-57-29407 (JP, A) JP-A-50 −9173 (JP, A) Jiko 29-16172 (JP, Y1)

Claims (2)

(57) [Claims] 1. A clay frame is formed on a lower press plate of a pair of upper and lower carbon press plates, and the inside of the frame is filled with an electrolyte powder, and directly hot-pressed by the pair of press plates. A method for producing an electrolyte plate of a molten carbonate fuel cell, characterized by comprising: 2. The molten carbonate fuel cell according to claim 1, wherein a plurality of electrolyte plates are simultaneously hot-pressed by stacking a plurality of press plates each having a clay frame formed thereon. A method for manufacturing an electrolyte plate.