JPS61198568A - Solid electrolyte fuel cell - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel cell system incorporating an excellent solid electrolyte as a thin film.

[Conventional technology]

Fuel cells, invented by Lord Grove in the first half of the 19th century, have gone through many changes and are now at the stage of practical use.

A fuel cell is a device that directly converts chemical energy into electrical energy, and its main components are an anode, a cathode, and an electrolyte. □Of these, an aqueous solution, molten salt, etc. are usually used as the electrolyte, but solid electrolyte fuel cells (Sold
80FC) has also made rapid progress in recent years. 5 OF
C is also called a third generation fuel cell, and compared to the 9-acid type (first generation) and molten salt type (second generation), it has the following features: 1) It does not require a noble metal catalyst such as platinum.

2) High energy conversion efficiency.

3) Low quality fuels such as coal gasification gas can also be used.

On the other hand, when commonly used electrolytes such as Zr02-CaO system are used, the operating temperature is 1000℃.
This poses a major problem in terms of materials.

Solid electrolyte fuel cells convert chemical energy directly into direct current electrical energy. However, as mentioned above, the operating temperature is about 700 DEG C. or higher, and usually as high as about 1000 DEG C., in order to make the solid electrolyte highly conductive. For this reason, restrictions in terms of materials are extremely severe.

Many electrolytes have been developed in the past, but one is stabilized zirconia, which is commonly used for fuel cells.
The electrical conductivity at 000°C is (ZrO2) (Ca
b) 2.5 x 10-2 (5een-')
Therefore, o, as o, is is not necessarily a large value, and it is necessary to make the film thinner as a fuel cell. Furthermore, a cerium-based electrolyte with good conductivity has recently been developed, but it goes without saying that even with this, it is necessary to make the film thinner.

[Problem that the invention seeks to solve]

In a typical solid electrolyte fuel cell, the cathode side of the electrolyte is in contact with the moisture in the oxygen (or the moisture in the air if air is used), and the anode side is in contact with the generated moisture. Therefore, CeO2-CaO system or Z r02-
When a CaO-based electrolyte or the like is used, there is a problem in that the performance of the multi-fuel cell deteriorates due to the digestion of CaO accompanying the reaction CaO+H2O→Cm(OH)z.

[Means and effects for solving the problems] The solid electrolyte fuel cell of the present invention has an alkaline earth element other than calcium on both sides of the solid electrolyte made of cerium oxide or zirconium oxide in which calcium oxide is dissolved or on the anode side. A solid electrolyte made of cerium oxide or zirconium oxide in which a divalent or trivalent oxide such as a metal or rare earth element □ is dissolved is deposited and incorporated into a battery.

According to such a solid electrolyte fuel cell, the electrolyte surface that comes into contact with the water-containing gas is an electrolyte that does not contain calcium oxide (e.g., sCo02-MgO system), and the gas does not reach the inside through this dense electrolyte. Since it does not penetrate, the electrolyte containing calcium oxide inside can be endowed with water availability. Note that the reason why the electrolyte not containing calcium oxide may be attached only to the anode side is because the amount of water on the anode side is smaller than that on the cathode side. Further, even if the surface is coated as described above, the electrolyte will not cause a rise in raw material costs because most of the electrolyte is CeO2-CaO-based or Zr02-CaO-based.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. In addition, in the following explanation (in order to simplify the names of each part,
The terms are defined as follows.

, Internal electrolyte: C@02-CaO system or Zr02-C
aO-based electrolyte Surface electrolyte: C@02-based or ZrO2-based electrolyte in which divalent or trivalent oxides such as alkaline earth or rare earth elements other than calcium are solidly dissolved. Solid used in the fuel cell according to the present invention. For example, as shown in FIG. 1, the electrolyte is one in which surface electrolytes 2.3 are attached to both anode and cathode sides of an internal electrolyte 1, respectively.

According to a fuel cell using such a solid electrolyte, the surface electrolyte 2.3 does not contain calcium oxide, so no reaction with water occurs, and since the surface electrolyte 2.3 is dense, water permeates through the surface electrolyte 2.3. It never reaches internal electrolyte 1. Therefore, calcium oxide dissolved in the internal electrolyte 1 does not disappear, and in particular, as the internal electrolyte 1, Ce
When using the 02-CaO system, deterioration of the excellent performance can be prevented.

゛The structure of the solid electrolyte used in the fuel cell according to the present invention is not limited to that shown in FIG. 1, but may be one in which the surface electrolyte 5 is attached only to the anode side of the internal electrolyte 4 as shown in FIG. 2. But that's fine.

Normally, the amount of water on the cathode side is smaller than on the anode side, so even with the configuration shown in FIG. 2, substantially the same effect as in the case of using the solid electrolyte shown in FIG. J11 can be obtained.

〔Effect of the invention〕

As detailed above, according to the present invention, it is possible to provide a solid electrolyte fuel cell that does not suffer performance deterioration due to reaction with moisture.

61

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a solid electrolyte used in a solid electrolyte fuel cell according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of a solid electrolyte used in a solid electrolyte fuel cell according to another embodiment of the present invention. 1.4... Internal electrolyte, 2.3.5... Surface electrolyte. Applicant Sub-Agent Patent Attorney Takehiko Suzue Figure 1 Figure 2

Claims (1)

[Claims] On both sides or on the anode side of a solid electrolyte made of cerium oxide or zirconium oxide in which calcium oxide is dissolved,
A solid electrolyte made of cerium oxide or zirconium oxide in which a divalent or trivalent oxide such as an alkaline earth metal other than calcium or a rare earth element is dissolved is deposited,
A solid electrolyte fuel cell characterized by being incorporated into a battery.