JP2980921B2 - Flat solid electrolyte fuel cell - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a structure of a solid oxide fuel cell, and more particularly to a flat solid electrolyte fuel cell in which a gas flow path is formed in an electrode.

[Conventional technology]

The plate-type solid electrolyte fuel cell is configured by connecting a plurality of unit cells each including three members of an air electrode, an electrolyte, and a fuel electrode in series by a layer called an interconnector. The output voltage of a cell is an open-circuit voltage of at most about 1 V, usually about 0.5 to 0.8 V.
A practical output voltage is obtained by connecting about several layers in series. Since the interconnectors are arranged between the unit cells and at both ends, when the unit cells are stacked in n layers, the interconnector requires n + 1 layers.

[Problems to be solved by the invention]

By the way, conventionally, a plate-like electrode is held by a plate electrolyte, and this is connected in series by a grooved interconnector. Currently, heat-resistant metals and lanthanum chromite-based ceramics are mainly used as the interconnector materials.The former is based on the fact that the difference in thermal expansion from other battery components is too large, and the chromium generated on the air electrode side surface is mainly chromium. There are drawbacks such as low electrical conductivity of the system oxide film, and extremely hard and extremely difficult to process, and the latter is difficult to obtain a dense body due to sinterability, It has the drawbacks that the electric conductivity is low in the whole, and there is a problem of breakage or strength deterioration due to processing due to brittleness.

Therefore, a structure capable of minimizing the processing of the interconnector is indispensable for practical use. Further, it is not preferable to make the interconnector thick enough to allow the groove processing, since this increases the internal resistance of the battery. In order to solve these problems, it is conceivable that the shape of the interconnector is made flat and the formation of the gas flow path currently performed in the interconnector is replaced by an electrode or an electrolyte member. Forming the flow path is not preferable because it increases the internal resistance of the battery similarly to the interconnector.

The present invention has been made in view of the above circumstances, and has a flat solid electrolyte fuel cell that can be easily manufactured and has a reduced internal resistance of a battery due to a structure in which a gas flow path is formed in an electrode member. The purpose is to provide.

[Means for solving the problem]

Considering the functional and structural characteristics required for electrodes and interconnectors in solid oxide fuel cells, the electrode members have functional properties as catalysts for gas reactions, and the interconnectors have structural properties that separate oxidizing and reducing gases. Is required. On the other hand, the functional characteristics for collecting current and the structural characteristics for forming the gas flow channel can be considered to be a method performed by the electrode or a method performed by the interconnector. Conventionally, these are performed on the interconnector side, but the present invention is characterized in that the role is assigned to the electrode side.

1 (a) and 1 (b) are diagrams for explaining the structure of the electrolyte plate or the interconnector of the present invention, and FIG. 2 is a diagram for explaining the structure of the unit battery. Electrolyte plate, 12 is air electrode green sheet, 13 is fuel electrode green sheet, 14 is interconnector plate, 15 is glass glass sheet for bonding, 16 is air electrode, 16a is air flow path, 17 is fuel electrode, 17a is fuel The channel 18 is an electrode protection member.

The fuel cell of the present invention is a method of assembling the electrolyte plate, the electrode, the interconnector, etc. in a state of an unfired molded body, crimping each other, and then integrally firing and joining each member to densify, or an electrolyte plate, Electrodes and interconnectors use sintered bodies, and any of them may be manufactured by a method of bonding them with slurry, green sheets, paste, etc. explain.

1 (a) and 1 (b), an air electrode green sheet 12 and a fuel electrode green sheet 13 are thermocompression bonded to both surfaces of an electrolyte plate 11 made of fired zirconia or an interconnector plate 14 made of lanthanum chromite ceramics. Then, an adhesive glass sheet 15 is thermocompression-bonded to both sides of each green sheet to form an electrolyte member and an interconnector member so that the green sheet does not come into contact with an oxidizing or reducing atmosphere. In this case, the electrode and the electrolyte, or the electrode and the interconnector, are bonded with a slurry or a green sheet of the electrode, the electrolyte, the same component as the interconnector, or a mixture thereof.

Next, as shown in FIG. 2, a green sheet is formed on both sides, and both sides of an electrolyte plate having a glass sheet adhered to both sides of the green sheet are sandwiched between an air electrode 16 and a fuel electrode 17. The protection member 18 is arranged and bonded. The cathode 16 is made of calcium or strontium doped lanthanum manganite or lanthanum cobaltite La
_1-x Ca _x MO ₃ , La _1-x Sr _x MO ₃ (M = Mn, Co,; x = 0.01-0.
6) The fuel electrode 17 is made of nickel or cobalt metal and cermet of zirconia-based or ceria-based ceramics (metal is 10 to 99% by volume), each sintered to a predetermined thickness, and parallel to the plane as shown in the figure. Are provided with a plurality of through holes 16a, 17a to form a gas flow path for air or fuel. The electrode protection member 18 is made of zirconia, and the two surfaces that are orthogonal to the surface of the plate electrode where the gas flow path is open have a reducing atmosphere in the air electrode if there is nothing to protect.
Since the fuel electrode is exposed to an oxidizing atmosphere,
It is provided to protect from the atmosphere. The electrode protection member and the electrolyte and the electrode protection member and the interconnector are joined with a sealant paste or a sealant green sheet. Between the unit cells thus formed, interconnectors having green sheets provided on both sides by the method shown in FIG.

In a battery having such a configuration, even if an electrode having a resistance smaller by about one digit than that of the interconnector is made thick enough to form a through hole, the resistance does not increase so much. Therefore, the resistance value can be reduced. Since the electrode, the electrolyte plate, and the interconnector are in surface contact over the entire surface, the contact resistance can be reduced, and as a result, the internal resistance of the battery can be reduced.

FIG. 3 is a diagram showing an example in which unit batteries are stacked in three stages and connected in series, 20 is a battery, 21a to 21c are unit cells, 22a to 22d are interconnectors, and the upper and lower interconnectors are: Although a green sheet is provided on the electrode side, it is not necessary to provide an electrode green sheet on the outer surface side. When enclosing in a container or the like, a glass sheet is adhered for sealing between the container and the container.

FIG. 4 is a view showing an example in which the laminated battery shown in FIG. 3 is housed in a cylindrical manifold. In the figure, 30 is a cylindrical manifold, 31 is a lid, 32 is a fuel supply pipe, 33 is a fuel exhaust pipe, 34
Is an air supply pipe, and 35 is an air exhaust pipe.

When the battery 20 is stored in the cylindrical manifold 30, four vertical corners of the rectangular battery are in contact with the manifold wall surface. Since the sealed space formed by the four sides and the wall forms a gas flow path, glass sealing is performed between the four sides and the wall. In addition, a glass sheet is adhered to the upper and lower interconnectors of the battery, and the manifold 30 and the lid are attached.
Seal between 31. Thus, by supplying air from the air inlet and supplying fuel from the fuel inlet, the fuel gas and the air react with each other, and an output can be taken out from an output lead wire (not shown).

FIG. 5 shows an example in which a plurality of grooves 41 are provided on one surface of the electrode 40 and this is used as a gas flow path. The surface on which the grooves are provided may be on either the electrolyte plate side or the interconnector side, or on both sides. It may be provided. However, in this case, the electrolyte plate,
Alternatively, since the contact between the interconnector and the electrode is lost on the entire surface, it is inevitable that the internal resistance increases as compared with the case where the through hole is used as a gas flow path.

[Action]

In the present invention, since the gas flow path is formed in the electrode plate and the interconnector is made flat without any particular processing, the thickness can be reduced and the resistance value can be reduced. Further, since the resistance of the electrode plate is about one digit lower than that of the interconnector, the resistance value does not increase even if the electrode plate is slightly thickened to form a gas flow path. Alternatively, since the contact area with the interconnector can be increased, the contact resistance can be reduced, and as a result, the internal resistance can be reduced. Further, the electrode plate, the electrolyte plate, and the interconnector are made of a sintered body, and are bonded to each other with a green sheet, a glass sheet, a slurry, or the like, thereby facilitating the production.

〔Example〕

 Hereinafter, examples will be described.

Example 1 A 50 mm × 50 mm × 0.2 mm thick yttria stabilized zirconia (hereinafter referred to as YSZ (Yttria Stabilized Zirco
nia)) 3 boards, 50m as interconnector board
calcia-added lanthanum chromite (hereinafter simply referred to as lanthanum chromite) plates of m × 50mm × 0.5mm thickness,
12 YSZ plates of 50mm × 5mm × 1mm as electrode protection members, 50mm × 40mm × 1mm thick as air electrode and fuel electrode respectively
Strontium-doped lanthanum manganite (hereinafter simply abbreviated as lanthanum manganite) plate and Ni / YSZ cermet plate each having 30 through-holes of 0.5 mmφ × 50 mm.
Prepared.

Further, a green sheet of lanthanum manganite, Ni / YSZ cermet, and sword-lime glass having a thickness of 0.1 mm was prepared by a doctor blade method.

First, as shown in FIG. 1, lanthanum manganite and Ni / YSZ green sheets each having a size of 50 mm × 40 mm × 0.1 mm were provided on both surfaces of the YSZ electrolyte plate 11 and the interconnector plate 14.
A glass green sheet having a size of 50 mm × 5 mm × 0.1 mm was thermocompression-bonded.

Next, after assembling the electrolyte plate, the interconnector, the electrode, and the electrode protection member as shown in FIGS. 2 and 3, they were assembled into a manifold as shown in FIG. 4 to produce a three-stage series connection type fuel cell. At the time of assembling, a glass sheet of 50 mm × 50 mm × 0.5 mm thickness was sandwiched on both upper and lower surfaces for sealing at a high temperature, and glass paste was applied to four corners.

The temperature was raised to 1000 ° C at 10 ° C / min., And pure oxygen was supplied to the air electrode and pure hydrogen was supplied to the fuel electrode. Obtained. The output voltage at a constant current of 5 A is 1.1 V, which indicates the effect of the present structure.

〔The invention's effect〕

As described above, according to the present invention, the gas flow path is formed on the electrode plate, and the interconnector is completely flat, so that the resistance can be reduced by making it thinner. Since it is about an order of magnitude lower than that, even if the electrode plate is slightly thickened to form the gas flow path, the resistance does not increase so much, and the contact area between the electrode and the electrolyte plate or the interconnector is also reduced. Since the contact resistance can be increased, the contact resistance can be reduced, and the internal resistance can be reduced as a whole. Further, the electrode plate, the electrolyte plate, and the interconnector use sintered bodies, and can be easily manufactured by bonding them with a green sheet, a glass sheet, a slurry, or the like.

[Brief description of the drawings]

FIG. 1 is a view for explaining the structure of an electrolyte plate or an interconnector of the present invention, FIG. 2 is a view for explaining the structure of a unit battery, FIG. 3 is a view showing a stacked battery, FIG. Is a view showing a state where the battery is incorporated in the manifold, and FIG.
The figure shows an example in which a groove is provided in the electrode. 11 ... electrolyte plate, 12 ... cathode green sheet, 13 ...
Fuel electrode green sheet, 14 ... interconnector plate, 15
... Glass sheet for bonding, 16 ... Air electrode, 16a ... Air flow path, 17 ... Fuel electrode, 17a ... Fuel flow path, 18 ... Electrode protection member.

Continued on the front page (72) Inventor Nobuaki Tagaya 1-3-1 Nishitsurugaoka, Oimachi, Iruma-gun, Saitama Prefecture Tonen Co., Ltd. (72) Toshihiko Yoshida 1-3- Nishitsurugaoka, Oimachi, Iruma-gun, Saitama 1. Inside the Tonen Research Laboratory (72) Atsushi Tsunoda 1-3-1 Nishitsurugaoka, Oi-machi, Iruma-gun, Saitama Prefecture (72) Inside the Tonen Research Laboratory (72) Takayuki Hoshina 1, Nishi-Tsurugaoka, Oi-machi, Iruma-gun, Saitama 3-1 Inside the Tonen Research Laboratory (56) References JP-A-63-259968 (JP, A) JP-A-60-195876 (JP, A) JP-A-60-107267 (JP, A) JP-A Sho 61-138464 (JP, A) JP-A-64-7475 (JP, A) JP-A-64-41172 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01M 8/00 -8/24

Claims (2)

(57) [Claims] A lanthanum manganite or lanthanum cobaltite doped with calcium or strontium across an electrolyte plate (La _1-x Ca _x MO ₃ , La _1-x Sr _x MO ₃ (M = Mn,
Co, x = 0.01-0.6)) and an anode electrode plate made of nickel or cobalt metal and a cermet of zirconia or ceria ceramics (metal volume ratio 10-99%) is laminated and unit cell A solid electrolyte fuel cell in which unit cells are stacked in a plurality of stages via an interconnector plate, wherein a through flow passage is formed in an electrode plate to form a gas flow passage, and each of an air electrode and a fuel electrode is formed. A flat electrolyte fuel cell, comprising: an electrode protection member made of zirconia that seals an electrode from an atmosphere on both sides parallel to a gas flow path. 2. The flat electrolyte fuel cell according to claim 1, wherein the electrode protection member and the electrolyte and the electrode protection member and the interconnector are joined by a joining layer made of a sealing paste or a sealing green sheet.