JPH0412468A - High-temperature fuel cell - Google Patents

Abstract

PURPOSE:To prevent the breakage of a container due to the thermal expansion difference between a main body and the container and the deterioration of the gas sealing property by forming guide/discharge paths of fuel gas and oxidizer gas in a stack structure of electrolyte plates and separators. CONSTITUTION:A cathode 12 and an anode 13 are formed on both faces of the flat electrolyte plate 11 of each cell. The electrolyte plates 11 each formed with the cathode 12 and anode 13 on both faces of each cell are stacked via separators 14 concurrently serving as gas passages and electric connectors. Grooves 14a, 14b are formed on both faces of the separator 14 to constitute the gas passages. The grooves 14a, 14b are arranged in parallel on both faces of the separator 14, and ridges on the surface becomes grooves on the back face. A center corrugated sheet section is constituted of the parallel grooves 14a, 14b, a frame 14c with the same plane as that of the ridges 14b on the surface and grooves 14d with the same plane as that of the ridges on the back face along the inside of the frame 14c are formed on the outer periphery, and the grooves 14a, 14b are sealed from the outside by the frame 14c and grooves 14d on the outer periphery when the separators 14 and the electrolyte plates 11 are stacked.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to high temperature fuel cells, and more particularly to the structure of a manifold for fuel gas and oxidant gas passages in a planar fuel cell integrated structure.

[Conventional technology]

As for high-temperature fuel cells, a pilot plant of approximately 5J has already been manufactured and is in operation at Westinghouse Electric Company in the United States, but this type is of the cylindrical type, and its low power density makes it difficult to downsize. be.

On the other hand, the flat plate type has the characteristic that it is possible to increase the power density by reducing the thickness per stage, but there are few demonstration examples because gas sealing is difficult. The lithographic type has a structure in which electrolyte plates with anodes and cathodes formed on both sides and separators (current collectors) with grooves on both sides and serving as gas passages and electrical connectors are stacked alternately. For supplying and discharging the agent gas, the above-mentioned aggregate is housed in a cylindrical container, sealed with gas, and an opening formed between the container and the aggregate is used as a manifold.

Generally, stabilized or partially stabilized zirconia is used as the electrolyte, and La (Sr) M is used as the cathode.
nO3 or la (Sr) COO3, and Ni/ZrO2 as the anode. Moreover, as a separator (current collector), LaCr0. Or heat-resistant alloys are used.

[Problems to be Solved by the Invention] In the flat plate type integrated structure described above, the fuel gas and oxidant gas supply and discharge manifolds are formed using containers outside the integrated body (battery main body). There are problems in that stress is generated due to differences in thermal expansion of the containers, which may damage the manifold and make gas sealing difficult. Further, since the battery body is housed in the container, there is a vertical gas sealing portion, which makes it difficult to retain the sealant.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention provides a flat plate fuel which is formed by alternately integrating electrolyte plates with anodes and cathodes formed on both sides and separators having grooves on both sides and serving as gas passages and electrical connectors. In a battery, a separator having a corrugated central portion and a peripheral wall extending along the outer periphery from one of the top or bottom surfaces of the corrugated sheet to the other is assembled via a flat electrolyte plate to form a separator and a separator. A gas passage for fuel gas and oxidant gas is formed by a space formed between the electrolyte plates, and the gas passage is sealed inside the assembly by the peripheral wall of the separator, and further, the electrolyte plate and the separator are joined. The present invention provides a high-temperature fuel cell characterized in that holes are provided in the electrolyte plate and gas passages for fuel gas and oxidant gas located on both sides of the electrolyte plate are connected to each other.

[For production]

By providing a gas-tight frame around the outer periphery of the separator, an introduction/exhaust path for fuel gas and oxidizing gas is formed inside the battery body, which is an assembly of electrolyte plates and separators. That is, there is no need for an external container for forming an introduction/exhaust path for fuel gas and oxidant gas. Therefore, damage to the container due to the difference in thermal expansion between the main body and the container and poor gas sealing properties are eliminated, and the overall size is further reduced. In addition, the number of gas sealing points is reduced as a whole, and there are no vertical sealing points, so that the retention of the sealant and the gas sealing property are improved. Furthermore, since the separator of the present invention has a structure that allows press processing or embossing, processing costs are reduced. Furthermore, since the fuel gas and the oxidizing gas flow in parallel (counterflow), it is expected that the output will be improved compared to a cross flow.

〔Example〕

FIG. 1 shows the arrangement of three-stage series cells in an expanded manner. In each cell, a cathode 12 and an anode 13 are formed on both sides of the flat electrolyte plate 11, respectively.

The electrolyte plate 11 is made of a plate-like material made of a known electrolyte such as an oxygen-conducting electrolyte such as partially stabilized zirconia or stabilized zirconia, and has a thickness of 0.05 to 0.3 m.
A suitable length is about m, more preferably about 0.08 to 0.25 mm. If it is thinner than 0.05 ohm, there is a problem in terms of strength, and if it exceeds 0.3 ohm, the current path becomes long, which is not preferable. Since the cathode 12 is on the oxygen passage side, it is made of a conductive material that is resistant to oxygen corrosion at high temperatures, and is formed in a porous shape.

For example, a conductive composite oxide powder such as LaxSr+-JnO* is applied. Application methods include brushing and screen printing. Other possible methods for producing the porous film include a CVD method, a plasma CVD method, a sputtering method, and a radiation method. The cathode 12 is formed to be porous to the extent that it is gas permeable. The anode 13 is on the hydrogen passage side and is made of a conductive material (for example,
(Ni/2rO2 cermet, etc.) is formed into a porous shape.

The anode 13 is also formed to be gas permeable. Furthermore, if the cathode and anode can be made into porous plates, they can also be used by attaching them to an electrolyte.

Electrolyte plates 11, each having a cathode 12 and an anode 13 formed on both sides of each cell, are integrated via a separator 14 which serves as a gas passage and an electrical connector. The separator 14 is made of metal or conductive ceramics such as La, Sr+, TCR03, etc.

As shown in FIG. 2, grooves 14a are formed on both sides of the separator 14.
14b are formed to constitute gas passages, respectively. Grooves 14a and 14b are arranged in parallel on both sides of the separator,
The ridges on the surface (joint part with the electrode) are the grooves on the back (gas passage)
becomes. For the central corrugated plate part (separator body part) consisting of the parallel grooves 14a and 14b, a frame 14c on the outer periphery is flush with the peaks 14b on the front surface, and a frame 14c along the inside of the frame 14c is flush with the peaks on the back surface. A groove 14d forming a plane is formed, so that when the separator 14 is integrated with the electrolyte plate 11, the grooves 14a and 14b are sealed from the outside by the frame 14c on the outer periphery and the groove 14d.

Holes 14e and 14f are formed at both ends of each of the parallel grooves 14a and 14b of the separator 14, so that the upper and lower gas passages 14a and 14b communicate with each other during integration. Because of this structure, if the material is metal, it must be manufactured by pressing, or if the material is ceramic, it must be processed from a bulk body by stamping in a green state and then sintering. do not.

This makes it possible to reduce the processing cost of the separator. Furthermore, since the fuel gas and the oxidant gas flow in parallel, it is expected that a higher power density will be obtained than in the conventional cross flow.

When the electrolyte plate 11 and the separator 14 are integrated and assembled, it is necessary to seal the space between the electrolyte plate 11 (more precisely, the electrodes 12 and 13) and the separator 14 to prevent gas leakage. For example, this may be sealed with a glass paste having a softening point of about 800°C. This glass paste softens sufficiently at battery operating temperatures (900-1000°C) to seal in gas. Figure 3 shows a cross section of this integrated structure.
Electrolyte plates 11 having cathodes 12 and anodes 13 formed on both sides and corrugated plate portions of separators 14 are stacked alternately.

When the peaks of the upper and lower corrugated plates are aligned, the gas passages 14a (A in FIG. 3) and 14b (F in FIG. 3) formed between the separator 14 and the electrolyte plate 11 are also aligned vertically. Therefore, if holes 14e and 14f are provided at the junction between separator 14 and electrolyte plate 11 as shown in FIG. 4, upper and lower gas passages 14a and 14b (A and F, respectively) will communicate with each other. However, although shown schematically in FIG. 4, in reality the holes 14a, 14a'14b
, 14b' are formed, so holes 14a and 14b1 hole 1
4a' and 14b' are not lined up in a line.

Because of this structure, as shown in FIG.
5.16 will be installed to supply gas. However, since the gas passages are provided through the cells, there is no need to provide a structure to directly supply gas to each cell.
Cells of concern in the case of external manifold type cells where the battery is installed in a container (especially in the case of metal separators)
Problems such as destruction of the manifold due to the difference in thermal expansion between the manifold and the manifold do not occur. In addition, gas sealing 25 is required only between the electrolyte plate 11 and separator 14 as shown in FIG. The sealing material is easy to hold.

Figure 1 shows a three-stage series high-temperature fuel cell fabricated according to the assembly pattern.

For the electrolyte plate 11, partially stabilized zirconia, which is zirconia to which 3 mole percent of ittria was added, was used. Further, as the separator 14, a plate-shaped electrolyte plate made of a nickel-based alloy and having dimensions of 50 x 50 x O and 2 mm was used. And Lao, 5Sro, +M on the oxygen passage side
Apply nO3 powder (average particle size approximately 5#m) to a thickness of 0 using the brush coating method.
, 10 to 0.50 mm to form the cathode 12, and on the hydrogen passage side, apply a cermet mixed powder of N+/Zr0z (10/1 weight ratio) to a thickness of 0.10 to 0.5 mm by brushing.
Anode 13 was prepared by coating the film to a thickness of 0 mm. The dimensions of the separator 14 are 50 x 50 mm, height 5 mm, and groove depth 4.0
mm.

The electrolyte plate 11 and separator 14 are integrated as shown in FIG.
00°C glass paste was applied to seal the gas.

As mentioned above, this glass paste has a battery operating temperature of 10
It softens at 00°C and seals in gas.

Gas piping was connected to the batteries thus assembled.

A platinum lead wire was welded to the electricity outlet for electrical connection.

The high temperature fuel cell thus produced was heated. It was heated at a rate of 1° C./min from room temperature to 150° C. to evaporate the solvent of the glass paste and the applied electrode. 150℃
The temperature was raised at a rate of 5°C/min up to -350°C. 350
℃ or higher, nitrogen gas was flowed into the hydrogen passage side to prevent oxidation of the anode, and the temperature was raised to 1000°C at a rate of 5°C/rnin. Thereafter, the temperature was maintained at 1000°C, hydrogen was flowed to the anode side, and oxygen was flowed to the cathode side, and power generation was started. The open circuit voltage was 3.8v. The discharge characteristics are shown in the table below.

Gas cross leakage was less than 0.3% of hydrogen.

〔Effect of the invention〕

According to the present invention, in a flat plate type high-temperature fuel cell, an introduction/exhaust passage for fuel gas and oxidizing gas is formed inside the integrated structure of an electrolyte plate and a separator, and the difference in thermal expansion between the main body and the container can be easily accommodated. Breakage of the container and poor gas sealing properties are solved, and the overall size is reduced. Furthermore, the retention of the sealant and gas sealing properties are improved as a whole. Furthermore, since the separator of the present invention has a structure that allows press processing or embossing, processing costs are reduced. Furthermore, since the fuel gas and the oxidant gas flow in parallel (counterflow), it is expected that the output will be improved compared to cross-flow.

[Brief explanation of drawings]

FIG. 1 is a developed view showing the integrated structure of a flat plate type high temperature fuel cell according to an embodiment, FIG. 2 is a three-sided view and a perspective view of a separator,
3 and 4 are partial cross-sectional views showing the internal integrated structure of the high temperature fuel cell according to the embodiment. 11... Electrolyte plate, 12... Cathode, 1
3... Anode, 14... Separator, 14a =
14b... Groove (gas passage), 14c = 14d.
...Frame portion, 14e, 14f...hole.

Claims (1)

[Claims] 1. An electrolyte plate with an anode and a cathode formed on both sides;
In a flat plate fuel cell, which has grooves on both sides and is made up of alternating stacks of gas passages and separators that also serve as electrical connectors, the central part is shaped like a corrugated plate, and one of the top or bottom surfaces of the corrugated plate is formed along the outer periphery. A separator with a peripheral wall extending from one to the other,
The fuel gas and the oxidant gas are integrated through a flat electrolyte plate, and a space formed between the separator and the electrolyte plate forms a gas passage for the fuel gas and the oxidizing gas, and the gas passage is connected to the inside of the aggregate by the peripheral wall of the separator. A high-temperature fuel cell characterized by having a sealed structure and further having holes provided at the joints between the electrolyte plate and the separator to connect gas passages for fuel gas and oxidizing gas located on both sides of the electrolyte plate. . 2. The separator has a central portion shaped like a corrugated sheet, an outermost peripheral portion that coincides with either the top surface or the bottom surface of the corrugated sheet, and a bottom along the inside of the outermost peripheral portion that is the top surface or the bottom surface of the corrugated sheet. Therefore, when the separators are integrated via a flat electrolyte plate, the spaces formed between the separator and the electrolyte plate form gas passages for fuel gas and oxidant gas, respectively. 2. The high-temperature fuel cell according to claim 1, wherein the gas passage is sealed inside the assembly.