JPH08222244A - Cell structure - Google Patents

Abstract

PURPOSE: To enhance strength of a sealing part or the like of an electrolytic film (an ion exchange membrane). CONSTITUTION: An anode electrode and a cathode electrode are respectively layered on both surfaces of an electrolytic film together with a sealing material, and separators having a fluid supply groove to supply fluid to these electrodes are respectively arranged on surfaces of these electrodes. A part coming into contact with a seal of the electrolytic film 11 and a part except a part corresponding to a clearance between the electrodes and the sealing material according to its necessity, are covered with a shielding plate 21, and plasma processing P is performed for a constant time, and polymerization is advanced on the basis of a functional group of a high polymer of electrolyte, and a chain network of the high polymer is developed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to high temperature steam electrolysis (SOE) using a solid electrolyte and a solid oxide fuel cell (SOFC).
cell structure in which the strength of the seal portion of the electrolyte membrane (ion exchange membrane) suitable for use in the ell) is improved.

[0002]

2. Description of the Related Art In an electrolyzer and a fuel cell using an ion exchange membrane as an electrolyte membrane, in order to increase the capacity (that is, the amount of an electrolyte substance in the electrolyzer, and the output power in the fuel cell),
The electrodes and the electrolyte membrane are laminated to form an electrolytic cell or a fuel cell stack.

The electrolyte membrane is sandwiched so that the liquid or gas in the electrolytic cell or the fuel cell stack does not leak outside (FIGS. 3 and 4). That is, for example, as an example of a cell structure of a flat-plate fuel cell, as shown in FIGS. 3 and 4, the fuel electrode is provided on both sides of the solid electrolyte membrane 11 with sealing materials 12 and 12 sealing the outer peripheral portions thereof. 13 and the air electrode 1
4 is bonded to form a cell plate, and further, outside the fuel electrode 13 and the air electrode 14, separators 15 and 15 each having a groove for supplying fuel and air are sandwiched to form a bonded body 16. There is.

[0004]

By the way, as shown in FIG. 4, the electrolyte membrane 11 is sandwiched by the sealing material 12 and the like, and the compressive stress exerted by the sealing portion and the electrode 1 are applied.
The portion corresponding to the gap S between the sealing material 12 and 3, 14 is
There was a risk of breakage due to the pressure difference between the fluid flowing between the anode and the cathode.

That is, in a fuel cell or electrolysis device using a polymer ion exchange membrane as an electrolyte membrane, a fuel cell stack or an electrolytic cell is formed by stacking electrodes and electrolyte membranes in multiple layers in order to increase the capacity. However, there is a possibility of damage due to excessive stress caused by the electrolyte membrane being sandwiched between the sealing materials and the like or due to the differential pressure of the flowing fluid.

In view of the above problems, it is an object of the present invention to provide a cell structure in which the strength of the seal portion of the electrolyte membrane (ion exchange membrane) is improved.

[0007]

An ion exchange membrane according to the present invention which achieves the above object is obtained by laminating an anode electrode and a cathode electrode together with a sealant on both surfaces of an electrolyte membrane and supplying a fluid to these electrodes. In a cell structure in which separators each having a fluid supply groove are provided on the surface of the electrode, a portion of the electrode contacting the electrolyte seal and, if necessary, a portion corresponding to the gap between the electrode and the sealing material are subjected to plasma treatment for a certain period of time. However, the polymerization is advanced based on the functional group of the polymer, and the chain network of the polymer is developed.

[0008]

In the above structure, as shown in FIG. 1, except the portion of the electrolyte membrane 11 that abuts on the seal and, if necessary, the portion corresponding to the gap between the electrode and the sealing material, is covered with the shield plate 21, and plasma treatment is performed for a certain period of time. Then, the polymerization proceeds based on the functional group of the polymer of the electrolyte to develop a network of polymer chains. That is, in the present invention, since the electrolyte membrane in the portion sandwiched by the sealing material or the like by lamination does not contribute to the electrochemical reaction as the electrolyte membrane, it is noted that a functional group involved in ion exchange is not required, and strength is enhanced. For this reason, this functional group is used to increase the degree of polymerization of the polymer by plasma treatment. As a result, based on the functional groups of the polymer, the polymerization by plasma treatment proceeds for a certain period of time,
The strength of the electrolyte membrane can be improved by developing a network of polymer chains.

FIG. 2 shows the relationship between the plasma treatment time for the polymer ion-exchange membrane and the accompanying membrane strength. As shown in FIG. 2, the polymer electrolyte membrane strength increases with the plasma treatment time. Then, it was found that the film strength decreased conversely after a certain period of time.

As a result, the portion of the electrolyte membrane that comes into contact with the sealing material for a predetermined period of time, and if necessary, the portion corresponding to the gap between the electrode and the sealing material is subjected to optimum plasma treatment to increase its strength and cause damage. It is possible to withstand the compressive stress and the differential pressure.

[0011]

EXAMPLES A preferred example of the present invention will be described below, but the present invention is not limited thereto.

FIG. 1 is a conceptual diagram of plasma treatment of an electrolyte. As shown in the figure, "Nafion 117" (trade name: DuPont) is used as an electrolyte membrane (ion exchange membrane) 11 cut into a square having a side of 250 mm, and a shielding plate 21 made of a Teflon material having a side of 200 mm is provided at the center thereof. Was placed in a vacuum chamber with a 250 mm square outer peripheral width of 25 mm exposed, and plasma treatment P was performed.

The plasma treatment P was carried out in an oxygen (O ₂ ) atmosphere at 0.5 Torr with an RF output of about 10 W. As a result of chemical analysis of the electrolyte membrane 11 after the plasma treatment, a decrease in sulfur (S) content was observed in the composition analysis, and an increase in the strength of the membrane 11 was observed. Therefore, there is a correlation between the strength of the electrolyte membrane 11 and the plasma treatment time as shown in FIG. 2, and it is possible to obtain sufficient strength by setting a predetermined time to obtain the desired membrane strength.

In the present embodiment, the atmosphere species (O ₂
Or a N _2), pressure, and plasma treatment was carried out based on such RF output, the present invention is not limited thereto, as long as to enhance the sealing portion by broad plasma treatment Any one will do.

The laminated state of the film and the electrode of the present invention will be shown and described with reference to FIGS. 3 and 4. By applying the plasma treatment method described above to the strength of the end portion of the electrolyte membrane 11, it becomes possible to withstand the tightening stress that causes breakage.

That is, since the electrolyte membrane 11 in the portion sandwiched by the sealing material 12 and the portion corresponding to the gap S does not contribute to the electrochemical reaction at all, a functional group due to ion exchange is not required, and therefore plasma treatment is performed for this purpose. By carrying out the polymerization, the polymer is advanced based on the functional group of the polymer, and the chain network of the polymer is developed to enhance the strength of a desired portion such as the outer peripheral portion of the electrolyte membrane of the electrolyte membrane 11. You can Therefore, by arranging the sealing materials 12 and 12 above and below the electrolyte membrane 11 after the plasma treatment, and further stacking the separators 15 and 15 above and below it, the stacking strength of the cell structure can be improved and the pressure of the fluid can be improved. There is no longer the risk of damage due to the difference.

[0017]

As described above, according to the present invention, since the strength of the outer peripheral portion of the electrolyte membrane can be increased, the sealing performance is improved and the gas difference is maintained with the same cell manufacturing method and laminated structure as the conventional one. The ability to withstand pressure is improved. Further, it is considered that the use of this film makes it possible to obtain a higher sealing property due to the new laminated structure.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a plasma processing situation according to a first embodiment of the present invention.

FIG. 2 is a correlation diagram between plasma processing time and film strength.

FIG. 3 is an exploded perspective view showing a laminated state of a film and an electrode according to the related art and the present invention.

FIG. 4 is a cross-sectional view showing a laminated state of a film and an electrode according to the related art and the present invention.

[Explanation of symbols]

 11 Electrolyte Membrane 12 Sealing Material 13, 14 Electrode 15 Separator 16 Bonded Body 21 Shielding Plate S Gap P Plasma Treatment

Claims (3)

[Claims] 1. An anode electrode and a cathode electrode are laminated on both surfaces of an electrolyte membrane together with a sealing material, and separators having fluid supply grooves for supplying a fluid to these electrodes are respectively disposed on the surface of the electrode. In the cell structure, a portion of the cell that contacts the electrolyte seal and, if necessary, a portion corresponding to the gap between the electrode and the sealing material are subjected to plasma treatment for a certain period of time, and the polymerization is advanced based on the functional group of the polymer. A cell structure characterized by developing a chain network. 2. The cell structure according to claim 1, wherein the electrolyte is used in a flat plate type high temperature steam electrolysis cell. 3. The cell structure according to claim 1, wherein the electrolyte is used in a fuel cell.