JP6861252B2 - Cells, cell stacking devices, modules, and module containment devices - Google Patents

Description

The present invention relates to cells, cell stacking devices, modules, and module housing devices.

In recent years, as next-generation energy, a fuel cell that can obtain electric power by using a fuel gas (hydrogen-containing gas) and an oxygen-containing gas (usually air) has been developed. A fuel cell (hereinafter referred to as a cell) has a structure in which a solid electrolyte layer is sandwiched between a fuel electrode layer and an air electrode layer. The cell generates electricity by heating the cell by flowing a fuel gas through the fuel electrode layer and an oxygen-containing gas through the air electrode layer (see, for example, Patent Document 1).

As an example of the cell, in the cell described in Patent Document 1, a power generation element portion in which a solid electrolyte layer is sandwiched between a fuel electrode layer and an air electrode layer is provided on a support. The support has a pair of faces and a pair of sides, contains Ni, and has a flat plate shape. A gas flow path is provided inside the support, and fuel gas flows through this gas flow path. The fuel electrode layer is provided on the support so as to cover the first surface and the side surfaces on both sides of the support. The solid electrolyte layer covers the fuel electrode layer and is provided from the first surface to the pair of side surfaces of the support. The air electrode layer is provided on the solid electrolyte layer so as to face the fuel electrode layer. Further, the interconnector layer is provided on the second surface, and has a function of taking out the current generated by the power generation element unit. The interconnector layer is preferably dense in order to suppress leakage of the fuel gas flowing through the gas flow path provided in the support and the oxygen-containing gas flowing outside the support. Further, Patent Document 1 discloses a solid oxide fuel cell capable of suppressing deformation when the interconnector layer is exposed to a reducing atmosphere.

Japanese Unexamined Patent Publication No. 2013-97978

However, when the oxygen-containing gas flowing outside the cell flows into the gas flow path inside the support, Ni contained in the support oxidatively expands, so that stress is applied to the interconnector layer in contact with the support, and this stress is applied. A crack will occur in the portion.

Therefore, an object of the present invention is to provide a cell, a cell stack device, a module, and a module accommodating device capable of suppressing the occurrence of cracks in the interconnector layer.

Cell of the present invention, a fuel electrode layer containing N i, and a solid electrolyte layer provided on the fuel electrode layer, an air electrode layer formed on the solid electrolyte layer, the solid electrolyte on the anode layer comprising interconnector layer a layer is provided at a site not provided, the. The interconnector layer is located closest to the fuel electrode layer , and is characterized by having a first layer having a higher porosity than other parts of the interconnector layer.

Further, the cell stack device of the present invention is characterized by including a cell stack in which a plurality of the above cells are arranged.

Further, the module of the present invention is characterized in that the cell stack device is housed in a storage container.

Further, the module accommodating device of the present invention is characterized in that the module is provided in an outer case and an auxiliary machine for operating the module.

According to the cell of the present invention, it is possible to suppress the occurrence of cracks in the interconnector layer. Even in a cell stack device, a module, and a module storage device using such a cell, it is possible to suppress the occurrence of cracks in the interconnector layer.

The cells are shown, (a) is a cross-sectional view, and (b) is a side view seen from the interconnector layer side. It is sectional drawing in the thickness direction of a part of an interconnector layer. It is an enlarged view of the vicinity of the pore in the cross-sectional view of FIG. A cell stack device is shown, where (a) is a side view and (b) is a cross-sectional view showing a part of (a) extracted. It is an external perspective view which shows an example of a fuel cell module. It is a perspective view which shows by omitting a part of the fuel cell apparatus.

A cell, a cell stack device, a module, and a module accommodating device will be described with reference to FIGS. 1 to 6. The same reference numerals shall be used for the same configuration. Hereinafter, an example of a solid oxide type hollow flat plate type cell as a cell will be described.

(Cell configuration)
1A and 1B show a form of a cell, in which FIG. 1A is a cross-sectional view thereof, and FIG. 1B is a side view taken from the side of the interconnector layer 6 in FIG. In both drawings, each configuration of cell 1 is partially enlarged and shown. FIG. 2 is a cross-sectional view of a part of the interconnector layer 6 in the thickness direction T. Let L be the longitudinal direction, W be the lateral direction, and T be the thickness direction.

The cell 1 includes a support 2, a fuel electrode layer 3, a solid electrolyte layer 4, an air electrode layer 5, and an interconnector layer 6.

The support 2 has an elliptical shape with a flat cross section, and has an elliptical columnar shape as a whole. Further, the support 2 is a porous body. As shown in FIG. 1, the support 2 has a flat plate shape having a pair of first surface n1 and second surface n2 and a pair of side surfaces m. In the example shown in FIG. 1, the pair of first surface n1 and second surface n2 face each other. In the example shown in FIG. 1, each pair of side surfaces m has an arcuate surface. The pair of side surfaces m may be flat surfaces.

Further, inside the support 2, a plurality of gas flow paths 2a penetrate in the longitudinal direction L at appropriate intervals. Various members, which will be described later, surround the outer circumference of the support 2.

As shown in FIG. 1, the fuel electrode layer 3 is provided on the first surface n1 of the support 2. In the example shown in FIG. 1, the fuel electrode layer 3 is provided on the support 2 so as to cover the first surface n1 of the support 2 and the side surfaces m on both sides. Further, since the fuel electrode layer 3 may be provided at a position facing the air electrode layer 5 via the solid electrolyte layer 4, for example, the fuel electrode layer 3 does not extend to the second surface n2 and the side surface m. It may be provided only on the first surface n1. Further, the fuel electrode layer 3 is a porous body.

As shown in FIG. 1, the solid electrolyte layer 4 covers the fuel electrode layer 3 and is provided from the first surface n1 of the support 2 to the pair of side surfaces m.

As shown in FIG. 1, the air electrode layer 5 is provided on the solid electrolyte layer 4 so as to face the fuel electrode layer 3. In the example shown in FIG. 1, it is the first surface n1 of the support 2 and is arranged outside the solid electrolyte layer 4. Further, the air electrode layer 5 is a porous body.

The interconnector layer 6 is provided on the second surface n2 of the support 2.

In the cell 1 described above, a portion in which the fuel electrode layer 3, the solid electrolyte layer 4, and the air electrode layer 5 are laminated functions as a power generation element portion. In order to generate power, an oxygen-containing gas such as air is flowed to the outside of the air electrode layer 5, and a fuel gas (hydrogen-containing gas) is flowed to the gas flow path 2a in the support 2, so that the fuel electrode layer 3 is fueled. Gas is supplied to heat the fuel electrode layer 3 to a predetermined operating temperature. Then, the current generated by such power generation is collected by the interconnector layer 6.

In the example shown in FIG. 1, the fuel electrode layer 3 and the solid electrolyte layer 4 extend from the first surface n1 to a part of the second surface n2 via the side surfaces m at both ends, and both ends of the solid electrolyte layer 4 Both ends of the interconnector layer 6 are laminated and joined to each other. As a result, the support 2 is surrounded by the solid electrolyte layer 4 and the interconnector layer 6, and the fuel gas flowing inside can be suppressed from leaking to the outside.

In the example shown in FIG. 1, the interconnector layer 6 having a rectangular planar shape is arranged so as to cover the support 2 from the upper end to the lower end in the longitudinal direction L, and the left and right side ends of the interconnector layer 6 are solid. It is superposed and bonded on both ends of the electrolyte layer 4.

(Explanation of each member of the cell)
The support 2 is required to be gas permeable in order to allow fuel gas to permeate to the fuel electrode layer 3, and to be conductive in order to be connected to the interconnector layer 6 to collect current. Therefore, as the support 2, conductive ceramics, cermet, or the like can be used. The conductivity is preferably 300 S / cm or more, particularly 440 S / cm or more, and the open porosity is preferably 25% or more in order to provide gas permeability.

The support 2 contains Ni. Ni here means metallic nickel. That is, Ni is distinguished from NiO (nickel oxide) described later.

In this example, the support 2 has Ni, NiO, and a specific rare earth oxide. Certain rare earth oxides are used to bring the coefficient of thermal expansion of the support 2 closer to the coefficient of thermal expansion of the solid electrolyte layer 4, Y, Lu, Yb, Tm, Er, Ho, Dy, Gd, A rare earth oxide containing at least one element selected from the group consisting of Sm and Pr is used. Specific examples of such rare earth oxides include Y ₂ O ₃ , Lu ₂ O ₃ , Yb ₂ O ₃ , Tm ₂ O ₃ , Er ₂ O ₃ , Ho ₂ O ₃ , Dy ₂ O ₃ , and Gd ₂ O. ₃ , Sm ₂ O ₃ , Pr ₂ O ₃ can be exemplified. Moreover, almost no solid solution or reaction with the Ni and NiO, about the same as the thermal expansion coefficient of the solid electrolyte layer 4, and from the viewpoint that it is inexpensive, of at least one of Y ₂ O ₃ and Yb ₂ O ₃ It should be. Further, in the present embodiment, Ni and NiO: rare earth oxides = 35: 65-65: in that the good conductivity of the support 2 is maintained and the coefficient of thermal expansion is approximated to that of the solid electrolyte layer 4. It exists in a volume ratio of 35. Further, when the support 2 contains both Ni and NiO, the ratio of Ni and NiO is not particularly limited, but Ni is always present. The support 2 may contain other metal components and oxide components as long as the required properties are not impaired.

Further, according to the present embodiment, the length of the first surface n1 and the second surface n2 of the support 2 in the lateral direction W is 15 to 60 mm, and the length of the side surface m (the length of the arc) is 2 to 2. It is 8 mm, the thickness between the first surface n1 and the second surface n2 of the support 2 is 1.5 to 5 mm, and the length of the support 2 in the longitudinal direction L is 10 to 50 cm.

The fuel electrode layer 3 causes an electrode reaction, and in this embodiment, it is made of porous conductive ceramics. For example, _{a material composed of ZrO 2} and Ni and / or NiO in which a rare earth oxide is solid-solved, or a material composed of CeO ₂ and Ni and / or NiO in which another rare earth oxide is solid-solved can be mentioned. As the rare earth oxide, those exemplified in the support 2 can be used, and examples thereof include a material composed of _{ZrO 2 (YSZ) in which Y 2} O ₃ is dissolved and Ni and / or NiO. _{In this embodiment, the content of ZrO 2 in which the rare earth oxide is solid-dissolved or CeO 2} in which the rare earth oxide is solid-dissolved in the fuel electrode layer 3 is in the range of 35 to 65% by volume, and Ni and / Alternatively, the content of NiO is 65 to 35% by volume. Further, the porosity of the fuel electrode layer 3 is, for example, 15% or more, particularly in the range of 20 to 40%, and the thickness thereof is 1 to 30 μm.

The solid electrolyte layer 4 has a function as a solid electrolyte layer 4 that bridges ions between the fuel electrode layer 3 and the air electrode layer 5, and at the same time, in order to prevent leakage between the fuel gas and the oxygen-containing gas. Is required to have a gas barrier property. In the present embodiment, 3 to 15 mol% of Y, Sc, portions containing an oxide of a rare earth element such as Yb stabilized or stabilized ceramic consisting ZrO ₂ (solid oxide) is used. Further, as a rare earth element, Y is used because it is inexpensive. The solid electrolyte layer 4, for example, may be a material of LaGaO ₃ type, as long as having the above characteristics, it is a matter of course may be other materials. In this embodiment, the thickness of the solid electrolyte layer 4 is 10 to 40 μm.

The air electrode layer 5 is not particularly limited as long as it is generally used, and can be formed of, for example, _{conductive ceramics made of a so-called ABO 3} type perovskite type oxide. Specifically, LaSrCoFeO ₃ , LaSrMnO ₃ , LaSrCoO _{3, and the} like can be used. The air electrode layer 5 needs to have gas permeability, and the open porosity is preferably in the range of 20% or more, particularly 30 to 50%.

For the interconnector layer 6, a lanthanum chromite-based perovskite-type oxide (LaCrO _3- based oxide) or a lanthanum strontium titanium-based perovskite-type oxide (LaSrTIO _3- based oxide) is preferably used. These materials have conductivity and are not easily reduced or oxidized even when they come into contact with fuel gas (hydrogen-containing gas) and oxygen-containing gas (air or the like).

Further, the interconnector layer 6 is preferably dense in order to suppress leakage of the fuel gas flowing through the gas flow path 2a provided in the support 2 and the oxygen-containing gas flowing outside the support 2.

By the way, the oxygen-containing gas flowing outside the cell 1 may flow into the gas flow path 2a inside the support 2. For example, when the supply amount of fuel gas decreases or when the supply of fuel gas is stopped. In these cases, since Ni contained in the support 2 oxidatively expands, stress is applied to the interconnector layer 6 in contact with the support 2, and cracks occur in this portion.

Therefore, as shown in FIG. 2, the interconnector layer 6 has the first layer 6a, and the first layer 6a is located closest to the support 2 side and has a higher porosity than the other portions. ing. The "other portion" here means a portion of the interconnector layer 6 other than the first layer 6a. With this configuration, since the first layer 6a has a relatively large number of pores, it is possible to relax the stress concentration on the interconnector layer 6 due to the oxidative expansion of Ni contained in the support 2. Therefore, it is possible to prevent cracks from occurring in the interconnector layer 6.

Further, the interconnector layer 6 contains Ni, and as shown in the example shown in FIG. 2, the interconnector layer 6 has a second layer 6b at a position farther from the support 2 than the first layer 6a. It is preferable that the second layer 6b has a lower porosity than the other portions. The "other portion" here means a portion of the interconnector layer 6 other than the second layer 6b. When lanthanum chromite is used as the material of the interconnector layer 6, the volume of the interconnector layer 6 expands in a reducing atmosphere. Further, by incorporating Ni in the interconnector layer 6, NiO exists as NiO in an oxidizing atmosphere, and NiO is reduced and exists as Ni in a reducing atmosphere. Therefore, in the reducing atmosphere, the lanthanum chromite is reduced and expanded, while NiO is reduced and contracted, so that the volume expansion of the entire interconnector layer 6 can be suppressed. Therefore, damage to the interconnector layer 6 can be suppressed. On the other hand, when the oxygen-containing gas flowing on the outer surface invades the inside of the interconnector layer 6, Ni in the interconnector layer 6 is oxidized and the volume expands, so that the volume of the entire interconnector layer 6 easily expands. Therefore, since the second layer 6b having a lower porosity than the other portions exists at a position farther from the support 2 than the first layer 6a, the invasion of oxygen-containing gas can be suppressed by the second layer 6b. .. Therefore, in the interconnector layer 6, the volume expansion of Ni can be suppressed in the region from the second layer 6b to the support 2 side, so that the damage of the interconnector layer 6 can be suppressed.

The content of Ni in the interconnector layer 6 is, for example, 5 to 15% by volume.

Further, the porosity of the first layer 6a may be 2 to 10%. When the porosity of the first layer 6a is 2% or more, the stress concentration on the first layer 6a can be further relaxed. On the other hand, when the porosity is 10% or less, the probability that open pores exist at the interface between the interconnector layer 6 and the support 2 can be suppressed, so that the area where the support 2 and the interconnector layer 6 are joined is Can be increased. Therefore, the bonding strength can be sufficiently maintained, and the peeling of the interconnector layer 6 can be suppressed. More preferably, the porosity of the first layer 6a is 3 to 9%.

Further, the porosity of the second layer 6b is preferably 0.2% or less. In this case, it is possible to further suppress the intrusion of oxygen-containing gas toward the inside of the interconnector layer 6.

Further, the interconnector layer 6 further has a third layer 6c between the first layer 6a and the second layer 6b, and the porosity of the third layer 6c is lower than that of the first layer 6a, and the second layer 6a. It should be higher than layer 6b. According to this configuration, the third layer 6c, which has a lower porosity than the first layer 6a, can further prevent the oxygen-containing gas flowing on the outer surface of the interconnector layer 6 from entering the inside of the interconnector layer 6. Further, since the porosity of the third layer 6c is between the first layer 6a and the second layer 6b, when the first layer 6a is deformed by the stress from the support 2, the porosity is low and it is difficult to be deformed. It is possible to suppress the transmission of stress to the two layers 6b. Therefore, it is possible to prevent damage from occurring inside the interconnector layer 6.

Further, as in the example shown in FIG. 3, the thickness (Tc) of the third layer 6c is preferably thicker than the thickness (Ta) of the first layer 6a and the thickness (Tb) of the second layer 6b. With this configuration, the above-mentioned effect of preventing the oxygen-containing gas from entering the connector layer 6 can be improved. Further, the effect of suppressing damage inside the interconnector layer 6 described above can be further improved.

Further, as shown in FIG. 3, it is preferable that the interconnector layer 6 contains Ni, and at least a part of the inner wall of the pores in the interconnector layer 6 is made of Ni. According to this configuration, when oxygen-containing gas enters the inside of the interconnector layer 6 or oxygen ions enter the inside of the interconnector layer 6 through the grain boundaries, Ni inside the interconnector layer 6 is oxidatively expanded. Also, the pores can absorb the volume expansion of Ni. Therefore, it is possible to prevent the volume of the interconnector layer 6 as a whole from rapidly expanding. Therefore, damage inside the interconnector layer 6 can be suppressed.

(Measuring method)
First, a method for measuring the porosity of the first layer 6a will be described. The area occupancy of the pores in the cross section of the first layer 6a is calculated, and this is used as the porosity. Specifically, SEM (Scanning Electron M) having a cross-sectional magnification of 1000 times in the thickness direction T of the interconnector layer 6
icroscopy (scanning electron microscope) images are acquired. The cross-sectional area of the entire first layer 6a in the SEM image is calculated, the total area of the pores of the first layer 6a is calculated, and "the total area of the pores / the total cross-sectional area of the first layer 6a" is calculated. This value is taken as the area occupancy of the pores. The same applies to the method of calculating the porosity of the second layer 6b and the third layer 6c.

Image analysis software can also be used to calculate the area of the pores. Further, the porosity calculated in one visual field may be regarded as the porosity of the first layer 6a, or the porosity is calculated by the same procedure in a plurality of visual fields, and the average value thereof is the porosity of the first layer 6a. May be regarded as.

The determination of the boundary between the first layer 6a and the other portion will be described. First, in the same SEM image as described above, a first line is drawn from the boundary line between the support 2 and the interconnector layer 6 toward the inside of the interconnector layer 6 at a distance of 1 μm. Then, the porosity in the region between the boundary line and the first line is measured. Next, a second line is drawn with an interval of 1 μm from the first line. Then, the porosity in the region between the first line and the second line is measured. If the porosity is less than 1%, the first line is the boundary between the first layer 6a and other portions. That is, the area from the first line to the boundary between the support 2 and the interconnector layer 6 is regarded as the first layer 6a. If the porosity in the region between the first line and the second line is 1% or more, a third line is drawn with an interval of 1 μm from the second line. Similarly, the porosity in the region between the second line and the third line is obtained, and if it is less than 1%, the second line is used as the boundary between the first layer 6a and the other portion. That is, the area from the second line to the boundary between the support 2 and the interconnector layer 6 is regarded as the first layer 6a. If it is 1% or more, the porosity is obtained by drawing a fourth line in the same manner. In this way, the porosity of the region having a width of 1 μm is measured and repeated until the porosity becomes less than 1%. Then, when it becomes less than 1%, the line immediately before it may be set as the boundary between the first layer 6a and the other portion.

Further, the determination of the boundary between the second layer 6b and other parts will be described. First, in the same SEM image as described above, a first line is drawn from the surface of the interconnector layer 6 far from the support 2 toward the inside of the interconnector layer 6 at an interval of 1 μm. Then, the porosity in the region between the surface and the first line is measured. Next, a second line is drawn with an interval of 1 μm from the first line. Then, the porosity in the region between the first line and the second line is measured. If this porosity is greater than 0.5%, the first line is the boundary between the second layer 6b and the other portion. That is, the area from the first line to the surface of the interconnector layer 6 is regarded as the second layer 6b. If the porosity in the region between the first line and the second line is 0.5% or less, a third line is drawn with an interval of 1 μm from the second line. Similarly, the porosity in the region between the second line and the third line is obtained, and if it is larger than 0.5%, the second line is used as the boundary between the second layer 6b and the other part. That is, the area from the second wire to the surface of the interconnector layer 6 is regarded as the second layer 6b. If it is 0.5% or less, the porosity is obtained by drawing a fourth line in the same manner. In this way, the porosity of the region having a width of 1 μm is measured and repeated until the porosity becomes larger than 0.5%. Then, when it becomes larger than 0.5%, the line immediately before it may be set as the boundary between the second layer 6b and the other portion.

The boundary of the third layer 6c is defined by the boundary between the first layer 6a and the other portion and the boundary between the second layer 6b and the other portion. That is, the area from the boundary of the first layer 6a to the boundary of the second layer 6b is regarded as the third layer 6b.

Next, a method for confirming the "first layer having a higher porosity than the other parts" will be described. As described above, after defining the boundary between the first layer 6a and the other portion, the porosity of the first layer 6a and the other portion is calculated, respectively. Then, it may be confirmed that the porosity of the first layer 6a is higher than that of the other portions.

In addition, a method for confirming that "the second layer has a lower porosity than the other parts" will be described. As described above, after defining the boundary between the second layer 6b and the other portion, the porosity of the second layer 6b and the other portion is calculated, respectively. Then, it may be confirmed that the porosity of the second layer 6b is lower than that of the other portions.

Further, a method for confirming that "the porosity of the third layer is lower than that of the first layer and higher than that of the second layer" will be described. This may be confirmed by identifying the first layer, the second layer, and the third layer, calculating the porosity of each layer, and comparing the numerical values.

Further, a method for confirming that "the third layer is thicker than the first layer and the second layer" will be described. This may be confirmed by identifying the first layer, the second layer, and the third layer, measuring the thickness of each layer, and comparing the numerical values.

(Production method)
An example of the method for producing the cell 1 of the present embodiment described above will be described. However, various conditions such as the material, particle size, temperature, and coating method described below can be changed as appropriate. Hereinafter, the "molded article" refers to a state before firing.

First, for example, a Ni and / or NiO powder, a powder of a rare earth oxide such as Y ₂ O _3, an organic binder, a mixture of a solvent to prepare a kneaded clay by extrusion molding using the clay A support molded body is prepared and dried.

As the support molded body, a calcined body that has been calcined at 900 to 1000 ° C. for 2 to 6 hours may be used.

Next, for example, according to a predetermined compounding composition, _{the raw materials of NiO and ZrO 2} (YSZ) in which _{Y 2} O ₃ is dissolved are weighed and mixed. After that, the organic binder and the solvent are mixed with the mixed powder to prepare a slurry for the fuel electrode layer.

Further, _{a sheet-like solid electrolyte layer is formed by forming a slurry of ZrO 2 powder in which Y 2} O ₃ is dissolved by adding toluene, a binder powder, a commercially available dispersant, etc. by a method such as a doctor blade. Make a body.

Then, the slurry for the fuel electrode layer is applied onto the obtained sheet-shaped solid electrolyte layer molded body and dried to form the fuel electrode layer molded body to form the sheet-shaped laminated molded body. The surface of the sheet-shaped laminated molded body of the fuel electrode layer molded body and the solid electrolyte layer molded body on the fuel electrode layer molded body side is laminated on the support molded body to form the molded body.

Subsequently, the interconnector layer material (for example, LaCrMgO ₃ type oxide powder), NiO
The powder, organic binder and solvent are mixed to prepare a slurry.

In order to prepare the slurries for the first layer, the second layer and the third layer, the amount of the pore-forming material is adjusted so that each layer has a desired porosity. The pore-forming material is formed of a resin that scatters during firing, for example, a cellulosic resin.

The pore diameter can be changed by the size of the pore-forming material, and the porosity can be changed by the amount of the pore-forming material.

Then, in the case of producing the interconnector layer 6 of the example shown in FIG. 2, the slurry for the first layer is applied onto the conductive support molded body and dried to prepare the first layer molded body, and then the first layer molded body is produced. A third-layer molded product is applied onto the one-layer molded product and dried to prepare a third-layer molded product, and a second-layer molded product is applied and dried to prepare a second-layer molded product, which is then laminated. Make a body.

Further, when the interconnector layer 6 of the example shown in FIG. 3 is produced, for example, the following method is used. First, a slurry is prepared from NiO powder and a pore-forming material. Next, the prepared slurry is made into granules by a spray dryer. The prepared granules, interconnector layer material (for example, LaCrMgO ₃ type oxide powder), organic binder and solvent are mixed to prepare a slurry. This slurry may be used to produce a laminated molded product as described above. As a result, the pore-forming material becomes pores in the interconnector layer, and the NiO powder becomes Ni that constitutes the inner wall of the pores.

Next, the above-mentioned laminated molded product is debindered and co-sintered (co-fired) at 1400 to 1450 ° C. for 2 to 6 hours in an oxygen-containing atmosphere.

Then, for _{example, La x Sr 1-x Co} y Fe 1-y O 3 having a predetermined particle size (hereinafter, simply referred to as LSCF) powders, an organic binder, a pore former, and a mixture of solvent cathode layer Prepare a slurry for use. This slurry is applied on the solid electrolyte layer by screen printing to form a molded product for an air electrode layer. This slurry is applied on the solid electrolyte layer by screen printing to form a molded product for an air electrode layer.

Next, the laminate in which the molded body for the air electrode layer is formed on the solid electrolyte layer is fired at 1100 to 1200 ° C. for 1 to 3 hours. In this way, the cell 1 of the present embodiment having the structure shown in FIG. 1 can be manufactured.

After that, it is preferable that the cell 1 is subjected to the reduction treatment of the support and the fuel electrode layer 3 by flowing hydrogen gas through the gas flow path. At that time, for example, it is preferable to carry out the reduction treatment at 750 to 1000 ° C. for 5 to 20 hours.

(Cell stack device)
FIG. 4 shows an example of a cell stack device configured by electrically connecting a plurality of the above-mentioned cells in series via a conductive member 13, and FIG. 4A shows a cell stack device 11. A schematic side view, (b) is a cross-sectional view of the broken line portion of the cell stack device 11 (a), and is an excerpt of the portion surrounded by the broken line shown in (a). In addition, in order to clarify the part corresponding to the part surrounded by the broken line shown by (a) in (b), it is shown by an arrow.

The cell stack device 11 includes a cell stack 12 in which a plurality of cells 1 are arranged side by side and each cell 1 is connected by a conductive member 13. Further, elastically deformable end conductive members 14 are provided at both ends of the plurality of cells 1 in the juxtaposed direction to sandwich the plurality of juxtaposed cells 1. Further, a current drawing portion 15 for drawing a current generated by power generation of the cell stack 12 (cell 1) is connected to the end conductive member 14. Further, the lower end of each cell 1 and the lower end of the end conductive member 14 are fixed to the gas tank 16 with an adhesive such as a glass sealing material.

Since the cell stack device 11 of the present embodiment also includes the cell 1 described above, the cell stack device 11 with improved durability can be obtained.

(module)
Next, the module 18 in which the above-mentioned cell stack device 11 is stored in the storage container 19 will be described with reference to FIG.

In the module 18 shown in FIG. 5, in order to obtain the fuel gas used in the cell 1, the reformer 20 for reforming the raw fuel such as natural gas or kerosene to generate the fuel gas is provided in the cell stack 12. It is placed above. Then, the fuel gas generated by the reformer 20 is supplied to the gas tank 16 via the gas flow pipe 21, and is supplied to the gas flow path (not shown) provided inside the cell 1 via the gas tank 16. Will be done.

Note that FIG. 5 shows a state in which a part (front and rear surfaces) of the storage container 19 is removed, and the cell stack device 1 and the reformer 20 housed inside are taken out rearward.

In such a module 18, since the cell stack device 11 with improved durability is housed, the module 18 with improved durability can be obtained.

(Module storage device)
Next, a module accommodating device 23 in which the above-mentioned module 18 and an auxiliary machine (not shown) for operating the module 18 are housed in an outer case will be described with reference to FIG.

In the module accommodating device 23 shown in FIG. 6, the inside of the exterior case composed of the columns 24 and the exterior plate 25 is vertically partitioned by the partition plate 26, and the upper side thereof is the module storage chamber 27 for accommodating the above-mentioned module 18. The lower side is configured as an auxiliary equipment storage chamber 28 for accommodating auxiliary equipment for operating the module 18.

Further, the partition plate 26 is provided with an air flow port 29 for flowing the air of the auxiliary machine storage chamber 28 to the module storage chamber 27 side, and a part of the exterior plate 25 constituting the module storage chamber 27 is provided. An exhaust port 30 for exhausting the air in the module storage chamber 27 is provided.

In such a module accommodating device, since the module 18 including the cell stack 11 with improved durability is accommodated, the module accommodating device 23 with improved durability can be obtained.

As described above, the present invention is not limited to the above-described embodiment, and various modifications and improvements can be made without departing from the gist of the present invention. For example, the fuel cell may be a fuel cell in which the air electrode layer, the solid electrolyte layer, and the fuel electrode layer are arranged in this order on the support. Further, for example, it may be a support that also serves as a fuel electrode layer.

Further, in the above embodiment, the fuel cell, the cell stack device using the fuel cell, the fuel cell module, and the fuel cell device have been described, but the present invention is not limited to this, and water vapor and voltage are applied to the cell. _{It can also be applied to an electrolytic cell (SOEC) that generates hydrogen and oxygen (O 2} ) by electrolyzing water vapor (water), and an electrolytic cell stacking device, an electrolytic module, and an electrolytic device including the electrolytic cell (SOEC).

(Preparation of sample)
A plurality of cells having different porosities in the first layer, the second layer, and the third layer were prepared. Specifically, as shown in Table 1, 10 samples (N = 10) were prepared.

The shape of the cell used in each sample was the same plate shape as in FIG. The length of the cell in the longitudinal direction was 20 cm, the length of the cell in the lateral direction was 26 mm, and the thickness was 2 mm.

The manufacturing method was the same as that described above. Incidentally, NiO powder used in Preparation of Support compacts is the average particle diameter of _0.5μm, Y 2 _{O 3} powder had an average particle diameter of 0.9 .mu.m. Support compacts, sintering - volume ratio after reduction, NiO is 48 _vol%, Y 2 _{O 3} was 52 vol%. As the raw material powder for the electrolyte layer _{, ZrO 2} powder having a particle size of 0.8 μm by the microtrack method in which _{8 mol% of Y 2} O ₃ was dissolved was used. The NiO powder used to prepare the fuel electrode molded product had an average particle size of 0.5 μm, and the ZrO _{2 powder in which Y 2} O ₃ was dissolved had an average particle size of 0.8 μm. The laminated molded body of the support molded body, the electrolyte layer sheet and the fuel electrode molded body was calcined at 1000 ° C. for 3 hours. As the material of the interconnector layer, La (Mg _0.3 Cr _0.7 ) _0.96 O ₃ was used. As the interconnector layer, a slurry for the first layer, a slurry for the third layer, and a slurry for the second layer were sequentially applied onto the support molded body and dried to prepare an interconnector layer molded body. The laminated molded product prepared as described above was co-fired at 1450 ° C. for 2 hours in an oxygen-containing atmosphere.

As the material of the air electrode, La _0.6 Sr _0.4 Co _0.2 Fe _0.8 O ₃ was used. The air electrode was formed by baking at 1100 ° C. for 4 hours. In the reduction treatment, hydrogen gas was passed through the inside of the cell, the support and the fuel electrode were reduced at 850 ° C. for 10 hours, and the mixture was cooled. The porosities of each layer of the obtained cells are as shown in Table 1.

With respect to the obtained cells, the first layer, the second layer and the third layer were specified by the method described above, and the porosity of each layer was calculated. The porosity of each layer was determined from an SEM photograph of 1000 times in an arbitrary cross section using an image analyzer.

(Crack test and peeling test)
Further, a cell stack device having the configuration shown in FIG. 4 is assembled from 10 cells manufactured under the same conditions, fuel gas is supplied in a temperature environment of 750 ° C., and the supply of fuel gas is stopped after a certain period of time. did. This fuel gas supply and stop cycle was repeated 360 times. After that, the cross section of the interconnector layer was observed with an SEM image for each of the 10 cells, and it was confirmed whether or not the interconnector layer had cracks. Table 1 shows the number of cells in which cracks occurred. Those having reached a length of 1 μm were recognized as cracks. In addition, after this cycle test, it was also confirmed that peeling occurred between the interconnector layer and the support for each of the 10 cells. Table 1 shows the number of cells in which peeling occurred. A part where the length of the portion where the interconnector layer and the support are not in contact reaches 1 μm is recognized as peeling.

(Crack test result)
Sample No. In 1, the number of cells in which the interconnector layer was cracked was six. This is because the porosity of the first layer was lower than that of the other parts.

Sample No. In 2 and 3, sample No. Compared with 1, the number of cells in which the interconnector layer was cracked was small. This is because the porosity of the first layer was higher than that of the other parts.

Sample No. In No. 4, the sample No. Compared with a few, the number of cells with cracks in the interconnector layer was small. This is because the porosity of the first layer was 2% or more.

Sample No. In 5 to 13, sample No. Compared with 4, the number of cells in which the interconnector layer was cracked was small. This is because the porosity of the first layer was 3% or more.

(Peeling test result)
Sample No. In 9 and 10, the number of cells in which peeling occurred between the interconnector layer and the support was three. This is because the porosity of the first layer was higher than 10%.

Sample No. In No. 8, the sample No. Compared with 9 and 10, the number of cells in which peeling occurred between the interconnector layer and the support was small. This is because the porosity of the first layer was 10% or less.

Sample No. In Nos. 2 to 7, the sample No. Compared with 8, the number of cells in which peeling occurred between the interconnector layer and the support was small. This is because the porosity of the first layer was 9% or less.

1: Cell 2: Support 2a: Gas flow path 3: First electrode layer (fuel electrode layer)
4: Solid electrolyte layer 5: Second electrode layer (air electrode layer)
6: Interconnector layer 6a: First layer 6b: Second layer 6c: Third layer

Claims (9)

The fuel electrode layer containing Ni and
A solid electrolyte layer provided on the fuel electrode layer and
An air electrode layer provided on the solid electrolyte layer and
An interconnector layer provided on the fuel electrode layer at a portion where the solid electrolyte layer is not provided is provided.
The cell is characterized in that the interconnector layer is located closest to the fuel electrode layer and has a first layer having a higher porosity than other portions. The interconnector layer contains Ni and contains Ni.
The interconnector layer has a second layer at a position farther from the fuel electrode layer than the first layer.
The cell according to claim 1, wherein the second layer has a lower porosity than other portions. The interconnector layer further has a third layer between the first layer and the second layer, and the porosity of the third layer is lower than that of the first layer and more than that of the second layer. The cell according to claim 2 , wherein the cell is also high. The cell according to claim 3, wherein the third layer is thicker than the first layer and the second layer. The cell according to any one of claims 1 to 4, wherein the porosity of the first layer is 2 to 10%. The interconnector layer contains Ni and contains Ni.
The cell according to any one of claims 1 to 5, wherein at least a part of the inner wall of the pores in the interconnector layer is made of Ni. A cell stack device comprising a cell stack in which a plurality of cells according to any one of claims 1 to 6 are arranged. A module characterized in that the cell stack device according to claim 7 is housed in a storage container. A module accommodating device comprising the module according to claim 8 and an auxiliary machine for operating the module in an outer case.

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