JPH056772A - Method for manufacturing molten salt fuel cell - Google Patents

Abstract

(57) [Abstract] [Purpose] To obtain a manufacturing method capable of easily obtaining a molten salt fuel cell having high adhesion without a gap between an electrode and an electrolyte holder. A step of forming an anode electrode 2 in which a metal sintered body is impregnated with an electrolyte made of molten carbonate, a step of forming a cathode electrode 3 in which the metal sintered body is impregnated with the electrolyte, and an organic substance A step of forming an electrolyte holder 1 containing a binder and having a softening temperature lower than that of the anode electrode 2 and the cathode electrode 3 by a doctor blade method; and the electrolyte holder 1 between the anode electrode 2 and the cathode electrode 3. And a step of constructing a unit cell by sandwiching the cell and a step of performing hot compression bonding on the unit cell under predetermined conditions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a molten salt fuel cell using a molten salt as an electrolyte, and more particularly to a method for manufacturing a molten salt fuel cell in which an electrode and an electrolyte holder are integrally formed.

[0002]

2. Description of the Related Art FIG. 3 is a side sectional view of a unit cell constituting a conventional molten salt fuel cell. In the figure, 1 is an electrolyte holder, 2 is an anode electrode impregnated with a molten salt as an electrolyte, and 3 is a cathode electrode impregnated with the same electrolyte as the anode electrode 2.

In manufacturing such a conventional molten salt fuel cell, the electrolyte holder 1, the anode electrode 2 and the cathode electrode 3 are individually manufactured as follows. For example, the electrolyte holder 1 is obtained by suspending the ceramic powder, which is an aggregate, in a mixed solution of an organic solvent, an organic binder and a plasticizer, and molding the slurry into a sheet having a certain thickness by the doctor blade method. dry. Then, several sheets of this dried sheet were overlapped and pressed to have a predetermined thickness, and then cut out to produce a predetermined size. The anode electrode 2 and the cathode electrode 3 are
The slurry obtained by suspending the metal powder was formed into a sheet shape in the same manner as the electrolyte holder 1, the sheet was sintered at high temperature in a furnace, and then the electrolyte was sprayed on the electrodes 2 and 3. The temperature is raised again in the furnace to melt the electrolyte and impregnate the electrodes 2 and 3 to manufacture. As shown in FIG. 3, each member produced in this manner was laminated with the electrolyte holder 1 on the cathode electrode 3 and then the anode electrode 2 thereon to form a unit cell of a fuel cell. . In order to stack the unit cells configured as described above in series to produce a laminated body as a fuel cell, it is necessary to allow hydrogen gas to flow through the anode electrode 2 and air and carbon dioxide through the cathode electrode 3. Therefore, a separator plate (not shown) is sandwiched between each unit cell.

[0004]

As described above, each member is first manufactured individually to form a unit cell, and then the unit cell is stacked to manufacture a fuel cell. Manufacturing of a conventional molten salt fuel cell In the method, it was very inefficient because it was necessary to stack the separator plate, the electrolyte holder, the anode electrode, and the cathode electrode, which were individually prepared, one by one. In addition, the flatness of individual electrolyte holders, electrodes, separator plates, etc. is limited to a few tens of μm, so that a gap is often generated between the members after the laminated body is formed due to the unevenness of the flatness. It was This gap was in an insulating state when the produced fuel cell was operated to generate electric power, and as a result, only part of the electrode was operated and the power generation efficiency was greatly reduced. Further, when a laminated body having a large number of laminated layers is operated as a battery, the gap is contracted during the operation of the battery, and the dimensions of the laminated body are largely changed. Therefore, a method of integrally manufacturing the electrolyte holder and the electrodes has been proposed. For example, Japanese Unexamined Patent Publication No. 58-87774 discloses a method of heating and pressure-bonding an electrolyte holder and an electrode. In this method, the electrolyte is melted and pressure-bonded. There is a device
It requires a fairly complicated process. Further, there is a problem that when the pressing is performed at such a high temperature and high pressure, the electrodes shrink and it becomes impossible to obtain a fuel cell having an optimal pore structure. Furthermore, in the method of forming an electrode by the doctor blade method on the electrolyte holder formed by the doctor blade method disclosed in JP-A-62-15768, the shape of the electrode formed on the electrolyte holder is independent. It is difficult to control with high precision, and since sintering of the electrode is performed with the electrode and electrolyte holder laminated, if several hundred laminates are constructed, the surface pressure at the top and bottom will be several kg / cm2.
However, it is virtually impossible to control the optimum pore structure of the electrode. In addition, the thickness of the electrode greatly shrinks with the operation time of the fuel cell, so that a gap is likely to be formed between the electrode and the electrolyte holder, and the characteristics of the fuel cell are significantly deteriorated. In this case, the dimensions of the laminated body change greatly, and there are problems such as a great obstacle in terms of connection with the gas supply manifold and holding the surface pressure of the laminated body.

The present invention has been made to solve the above problems, and can easily obtain an integrated molten salt fuel cell unit cell in which no gap is formed between an electrode and an electrolyte holder. It is intended to provide a manufacturing method.

[0006]

A method for manufacturing a molten salt fuel cell according to the present invention comprises a step of forming an anode electrode in which a metal sintered body is impregnated with a molten carbonate electrolyte, and the electrolyte. A step of forming a cathode electrode in which a metal sintered body is impregnated with a metal sintered body, a step of forming an electrolyte holder containing an organic binder and having a lower softening temperature than the anode electrode and the cathode electrode by a doctor blade method; The method comprises a step of forming a unit cell by sandwiching the electrolyte holder between an electrode and a cathode electrode, and a step of performing hot compression bonding on the unit cell so as to satisfy a predetermined condition.

A method of manufacturing a molten salt fuel cell according to a second aspect of the present invention comprises a step of forming an electrolyte holder made of ceramics, and an anode electrode obtained by impregnating a metal sintered body with an electrolyte made of molten carbonate. And a step of forming a cathode electrode in which the metal sintered body is impregnated with the electrolyte, and an adhesive sheet containing an organic binder and having a lower softening temperature than the anode electrode, the cathode electrode and the electrolyte holder. A step of forming a unit cell by sandwiching the pressure-sensitive adhesive sheet between the anode electrode and the cathode electrode and the electrolyte holder, and a step of performing hot pressure bonding satisfying a predetermined condition on the unit cell. Be prepared.

[0008]

In the method for producing a molten salt fuel cell according to the present invention, after the unit cell of the fuel cell is constructed as described above,
By carrying out hot pressure bonding, the organic binder contained in the electrolyte holder is softened so as to enter the gap between the electrode and the electrolyte holder and fill the gap.

In the method for producing a molten salt fuel cell according to the second aspect of the present invention, the unit cell of the fuel cell is formed as described above, and then hot pressure bonding is performed to soften the organic binder contained in the pressure-sensitive adhesive sheet and thereby the electrode.・ Move into the gap between the electrolyte holders to fill this gap.

[0010]

EXAMPLES Example 1. FIG. 1 is a side sectional view of a unit cell of a molten salt fuel cell showing one embodiment of the present invention. In the figure, 1 is 64% by weight of LiAlO2 as an aggregate, 21% by weight of polyvinyl butyral as an organic binder,
An electrolyte holder prepared by the doctor blade method with a composition ratio of polyethylene glycol of 15% by weight as a plasticizer, 2 is a carbonate which is an electrolyte in 90% of the pore volume of a sintered Ni.Al alloy porous body. (Li2CO3 +
K2CO3, molar ratio 62:38) was impregnated at 650 ° C. to prepare an anode electrode, and 3 was a carbonate (Li 2) which was an electrolyte in 60% of the pore volume of a sintered Ni porous body.
This is a cathode electrode prepared by impregnating CO3 + K2CO3, molar ratio 62:38) at 650 ° C.

First, the electrolyte holder 1, the anode electrode 2 and the cathode electrode 3 are individually formed into a predetermined shape in the same manner as in the conventional example, and then the cathode electrode 3 and the electrolyte holder are held on a press machine. The body 1 and the anode electrode 2 are positioned and stacked in this order to form a unit cell of a fuel cell. Next, this unit cell is heated to 100 ° C. to 13 ° C. which exceeds the softening point of the organic binder contained in the electrolyte holder 1.
Raise the temperature to 0 ° C. In addition, the electrodes 2 and 3 and the electrolyte holder 1 are integrated by applying pressure at the same time as the temperature is raised. In determining the pressurizing pressure, a hot compression test was previously performed using a unit cell of the same specifications. , The surface pressure is 50
When it is set to kg / cm2, the amount of thickness deformation of the electrolyte holder 1 is 30 to
When the pressure is 60 μm or more, the electrolyte holder 1 is crushed too much and deformed. When the pressure is less than 60 μm, the amount of deformation of the electrolyte holder 1 is too small and the electrodes 2, 3
Since the electrolyte holder 1 and the electrolyte holder 1 did not adhere to each other,
It was pressed for several minutes at a surface pressure of 0 kg / cm 2. With this pressurizing pressure, the amount of deformation of the electrodes 2 and 3 is 10 μm or less for the anode electrode 2 and 30 μm or less for the cathode electrode 3, and the thickness of the unit cell including the electrolyte holder 1, the anode electrode 2 and the cathode electrode 3 is The thickness was 70 μm thinner than the sum of the thickness of each member before hot press bonding. Further, when the cross section of the integrated product was observed, it was confirmed that the electrolyte holder 1 entered the gap between the electrodes 2 and 3 and the electrolyte holder 1 and was bonded uniformly without a gap. When a battery was operated using this unit cell, the resistance could be reduced by 50 mΩcm 2 as compared with the case of using the unit cell manufactured by the method of the conventional example.

Example 2. FIG. 2 is a side sectional view of a unit cell of a molten salt fuel cell according to the second invention. In the figure, 1 is 65% by weight of LiAlO2 as an aggregate, 20% by weight of polyvinyl butyral as an organic binder, and 15% by weight of polyethylene glycol as a plasticizer.
The electrolyte holder was prepared as a composition ratio of 2 and 2 is a carbonate (Li2CO3 + K2CO3, molar ratio 6%) as an electrolyte in 90% of the pore volume of the sintered Ni.Al alloy porous body.
2:38) was impregnated at 650 ° C. to prepare an anode electrode, and 3 is a sintered porous body of Ni having a pore volume of 6
A cathode electrode prepared by impregnating 0% with a carbonate (Li2CO3 + K2CO3, molar ratio 62:38) as an electrolyte,
Reference numeral 4 is a pressure-sensitive adhesive sheet produced by using 63% by weight of LiAlO2 as an aggregate, 22% by weight of polyvinyl butyral as an organic binder, and 15% by weight of polyethylene glycol as a plasticizer.

First, the electrolyte holder 1, the anode electrode 2,
The cathode electrode 3 and the adhesive sheet 4 are individually formed into a predetermined shape in the same manner as in the conventional example, and then the cathode electrode 3, the adhesive sheet 4, the electrolyte holder 1,
The pressure-sensitive adhesive sheet 4 and the anode electrode 2 are positioned and stacked in this order to form a unit cell of a fuel cell. Next, this unit cell is heated to 100 ° C. to 130 ° C., which is higher than the softening point of the organic binder contained in the adhesive sheet 4.
Further, the same hot-pressing test as in Example 1 was conducted, the pressurizing pressure was determined to be 50 kg / cm 2, and the unit cell was pressed for several minutes. Electrodes 2, 3 at this pressure
The amount of deformation of the anode electrode 2 is 10 μm or less, the cathode electrode 3 is 30 μm or less, and the electrolyte holder 1 is 10 μm or less. The unit cell including the electrolyte holder 1, the anode electrode 2, the cathode electrode 3 and the adhesive sheet 4 Was 9 μm thinner than the sum of the thicknesses of the respective members before hot press bonding. Further, when the cross section of this integrated product was observed, it was confirmed that the pressure-sensitive adhesive sheet 4 entered between the electrodes 2 and 3 and the electrolyte holding body 1 without a gap and was integrated. Further, when a battery was operated using this unit cell, the resistance was 50 compared to the case where the unit cell manufactured by the method of the conventional example was used.
mΩcm ² could be reduced.

In the examples described above, polyvinyl butyral is used as the organic binder and polyethylene glycol is used as the plasticizer in the preparation of the slurry of the electrolyte holder 1 and the adhesive sheet 4, but these are the molten salts used as the electrolyte. Other materials may be used as long as they soften below the melting point. In addition, the electrolyte holder 1,
Although LiAlO2 is used as the aggregate of the adhesive sheet 4, these may be other ceramic powders. Furthermore, in the pressure-sensitive adhesive sheet 4, metal powder may be mixed into the aggregate as a reinforcing body. Further, a reinforcing body for preventing cracks such as a metal mesh or ceramic fiber may be embedded in the electrolyte holder 1 or the adhesive sheet 4. Further, the cathode electrode may be an oxide of a metal sintered body. In short, according to the present invention, the organic substance contained in the electrolyte holder 1 or the pressure-sensitive adhesive sheet 4 is heated to be softened so as to enter the gap between the electrodes 2 and 3 and the electrolyte holder 1 to fill the gap. This is to manufacture an integrated product of the electrodes 2 and 3 which are the unit cells of the fuel cell and the electrolyte holding body, and the combination of materials, compositions and devices to be used may be any combination as long as the above-mentioned conditions are satisfied. May be.

[0015]

As described above, according to the present invention, there is provided a unit cell of a fuel cell which is an integrated body of an electrode and an electrolyte holding body having a predetermined shape having a high adhesiveness with no gap between the electrode and the electrolyte holding body. There is an effect that it can be easily manufactured.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a unit cell of a molten salt fuel cell which is an embodiment of the present invention.

FIG. 2 is a side sectional view showing a unit cell of a molten salt fuel cell which is an embodiment of the second invention.

FIG. 3 is a side sectional view showing a unit cell of a conventional molten salt fuel cell.

[Explanation of symbols]

1 Electrolyte support 2 Anode electrode 3 cathode electrode 4 Adhesive sheet

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shoji Yoshioka             8-1-1 Tsukaguchihonmachi, Amagasaki-shi Mitsubishi Electric             Central Research Institute Co., Ltd.

Claims (2)

[Claims] 1. A step of forming an anode electrode by impregnating a metal sintered body with an electrolyte made of molten carbonate, a step of forming a cathode electrode in which the metal sintered body is impregnated with the electrolyte, and an organic material. A step of forming an electrolyte holder containing a binder and having a lower softening temperature than the anode electrode and the cathode electrode by a doctor blade method, and sandwiching the electrolyte holder between the anode electrode and the cathode electrode to form a unit cell And a step of hot-pressing the unit cell to satisfy the following conditions. (A) A temperature above the temperature at which the electrolyte holder softens and below the temperature at which the organic binder contained in the electrolyte holder decomposes or burns, or below the temperature at which the electrolyte impregnated into the anode electrode and the cathode electrode melts. To be. (B) Press-bonding under a pressure at which the anode electrode and the cathode electrode are deformed. 2. A step of forming an electrolyte holder made of ceramics, a step of forming an anode electrode in which a metal sintered body is impregnated with an electrolyte made of molten carbonate, and the electrolyte being made into a metal sintered body. Forming an impregnated cathode electrode; forming an adhesive sheet containing an organic binder and having a softening temperature lower than that of the anode electrode, the cathode electrode and the electrolyte holder, and holding the anode electrode, the cathode electrode and the electrolyte A method for producing a molten salt fuel cell, comprising: a step of sandwiching the pressure-sensitive adhesive sheet with a body to form a unit cell; and a step of hot-pressing the unit cell to satisfy the following conditions. (A) is at or above the temperature at which the pressure-sensitive adhesive sheet softens,
Further, the temperature is not higher than the temperature at which the organic binder contained in the pressure-sensitive adhesive sheet decomposes or burns, or the temperature at which the electrolyte impregnated in the anode electrode and the cathode electrode melts. (B) Press-bonding under a pressure at which the anode electrode, the cathode electrode and the electrolyte holder are deformed.