JP6803437B2 - Cell, cell stack device, module and module storage device - Google Patents

Description

The present invention relates to cells, cell stack devices, modules and module storage devices.

In recent years, as next-generation energy, a cell stack device in which a plurality of solid oxide fuel cell cells (hereinafter, may be simply referred to as cells), which are one type of cells, are electrically connected in series is provided as a storage container. Various fuel cell devices housed inside have been proposed.

Such a cell has a structure in which a solid electrolyte layer is sandwiched between a fuel electrode and an oxygen electrode. The cell generates electricity by passing a fuel gas through the fuel electrode and an oxygen-containing gas through the oxygen electrode and heating the cell (see, for example, Patent Document 1).

Further, Patent Document 1 describes that a first layer having a strength higher than that of a solid electrolyte layer is provided in order to improve the strength of the cell.

International Publication No. 2014/208730

However, when the first layer as in Patent Document 1 is used, the long-term reliability may decrease as the power generation using the above-mentioned cell is repeated.

An object of the present invention is to provide cells, cell stacking devices, modules, and module accommodating devices with improved long-term reliability.

The cell of the present invention has an element portion in which the first electrode, the solid electrolyte layer, and the second electrode are laminated in this order, and the solid electrolyte layer has a first portion where the second electrode does not overlap. A first layer composed of a large number of particles and thicker than the solid electrolyte layer is provided in at least a part of the first site, and the particles are zirconia containing a rare earth element oxide. system oxide, ceria based oxide containing a rare earth element oxide, and are either of lanthanum gallate-based oxide, in the first layer, the average particle diameter of the surface layer portion, than the average particle diameter of the inner It's getting bigger.

The cell stack device of the present invention is characterized in that it includes a plurality of the above cells and electrically connects the plurality of cells.

The module of the present invention is characterized in that the cell stack device described above is housed in a storage container.

The module storage device of the present invention is characterized in that the above-mentioned module and an auxiliary machine for operating the module are stored in an outer case.

The cell of the present invention can be a cell with improved long-term reliability. Long-term reliability can also be improved in a cell stack device, a module, and a module accommodating device using such a cell.

An example of a cylindrical type and a horizontal stripe type cell is shown, in which (a) is a partially broken perspective view, (b) is a vertical sectional view, (c) is a perspective view, and (d) is a vertical sectional view on one end side. Is. A hollow flat plate type cell is shown, where (a) is a cross-sectional view, (b) is a cross-sectional view on one end side, and (c) is a side view seen from the oxygen electrode side. An example of the cell stack device is shown, (a) is a side view schematically showing the cell stack device, and (b) is a cross-sectional view showing a part of the part of the cell stack device (a) surrounded by a broken line in an enlarged manner. Is. It is a side view which shows the state which fixed the cell of FIG. 2 to a gas tank with a joining material. It is an external perspective view which shows an example of a module. It is a perspective view which shows by omitting a part of a module accommodating device.

A cell, a cell stack, a module, and a module accommodating device will be described with reference to FIGS. 1 to 6.

Hereinafter, an example of a solid oxide fuel cell will be described as a cell constituting the cell stack.

1A and 1B show an example of a cylindrical and horizontal striped cell, in which FIG. 1A is a partially broken perspective view, FIG. 1B is a vertical sectional view, FIG. 1C is a perspective view, and FIG. 1D is one end. It is a vertical sectional view of a side. Hereinafter, the same configuration will be described using the same reference numerals. First, the configuration of each cell will be described below.

The cell 100 shown in FIGS. 1 (a) and 1 (b) shows an example of a so-called cylindrical cell, which is dense on a porous fuel electrode (first electrode) 3 which also serves as a tubular support. Solid electrolyte layer 4 and porous oxygen electrode (second electrode) 6 are laminated in this order to form a cylindrical shape. The inside of the fuel electrode 3 is a fuel gas passage 2 through which the fuel gas flows, and is provided along the longitudinal direction L.

The solid electrolyte layer 4 is preferably made of a gas-blocking ceramic and has a thickness of 40 μm or less, and particularly preferably 20 μm or less, and further preferably 15 μm or less from the viewpoint of improving power generation performance.

In the cylindrical cell 100, the portion where the fuel electrode 3, the solid electrolyte layer 4, and the oxygen electrode 6 overlap functions as an element portion a for generating electricity. That is, oxygen-containing gas such as air is passed outside the oxygen electrode 6, and fuel gas (hydrogen-containing gas) is passed through the fuel gas passage 2 to heat the gas to a predetermined operating temperature to generate power.

Further, as shown in FIG. 1B, in the present embodiment, the solid electrolyte layer 4 has a portion where the oxygen poles 6 do not overlap. For example, one end (lower end) and the other end (upper end) of the cell 100. Further, in the example shown in FIG. 1 (b), a first layer 7 described later is provided at one end of a portion where the oxygen poles 6 do not overlap.

The cell 200 shown in FIGS. 1 (c) and 1 (d) shows an example of a so-called horizontal stripe type cell, which has a flat cross section and has an elliptical tubular body (in other words, an elliptical columnar shape) as a whole. It includes an insulating support 1. Inside the support 1, a plurality of fuel gas passages 2 are formed so as to penetrate the cell 300 in the longitudinal direction L at appropriate intervals.

As can be understood from the shape shown in FIG. 1C, the support 1 is formed by a pair of flat surfaces n parallel to each other and an arcuate surface (side surface) m connecting the pair of flat surfaces n. It is configured. Both sides of the flat surface n are formed substantially parallel to each other, and a plurality of porous fuel poles 3, a dense solid electrolyte layer 4, and a porous oxygen pole 6 are formed as a set on each flat surface n. The sets are provided so as to be adjacent to each other, and these are electrically connected by a dense interconnector layer 8. The portion where the fuel electrode 3, the solid electrolyte layer 4, and the oxygen electrode 6 overlap each other functions as an element portion a for generating electricity. That is, oxygen-containing gas such as air is passed outside the oxygen electrode 6, and fuel gas (hydrogen-containing gas) is passed through the fuel gas passage 2 in the support 1 to generate power by heating to a predetermined operating temperature. The thickness of the solid electrolyte layer 4 is preferably 40 μm or less, particularly preferably 20 μm or less, and further preferably 15 μm or less from the viewpoint of improving power generation performance.

Further, in the portion where each of these sets is not provided, a solid electrolyte layer 4 made of ceramics having a gas blocking property is provided in order to prevent the gas flowing through the fuel gas passage 2 from leaking to the outside. That is, the solid electrolyte layer 4 and the interconnector layer 8 are configured so that the fuel gas flowing inside does not leak to the outside.

Further, in FIG. 1D, an example in which the fuel pole 3 and the oxygen pole 6 are each formed into one layer on the insulating support 1 is shown, but each may be composed of two or more layers. The fuel electrode 3 may be in a form in which at least a part thereof is embedded in the support 1.

Even in this horizontal stripe type cell 200, as shown in FIG. 1D, the solid electrolyte layer 4 has a portion where the oxygen poles 6 do not overlap. For example, one end (lower end) of the cell 200. In the example shown in FIG. 1 (d), the first layer 7 described later is provided at one end of the portion where the oxygen poles 6 do not overlap.

2A and 2B show an example of a hollow flat plate type cell 300, in which FIG. 2A is a cross-sectional view thereof, FIG. 2B is a cross-sectional view on one end side, and FIG. 2C is a side view seen from the oxygen electrode side. It is a figure.

The cell 300 shown in FIG. 2 has a hollow flat plate type, a flat cross section, and a conductive support 1 having an elliptical tubular body (in other words, an elliptical columnar shape) as a whole. Inside the support 1, a plurality of fuel gas passages 2 are formed so as to penetrate in the longitudinal direction L of the cell 300 at appropriate intervals, and the cell 300 is provided with various members on the support 1. Has a structure.

In the cell 300 shown in FIG. 2, as can be understood from the shape shown in FIG. 2A, the support 1 connects a pair of flat surfaces n parallel to each other and a pair of flat surfaces n, respectively. It is composed of an arcuate surface (side surface) m. Both sides of the flat surface n are formed substantially parallel to each other, and a porous fuel electrode (first electrode) 3 covers one flat surface n (one side main surface: lower surface) and both arcuate surfaces m. The solid electrolyte layer 4 is arranged so as to cover the fuel electrode 3. The solid electrolyte layer 4 is made of a gas-blocking ceramic and has a thickness of 40 μm or less, particularly 20 μm or less, and more preferably 15 μm or less from the viewpoint of improving power generation performance.

Further, on the surface of the solid electrolyte layer 4, a porous oxygen electrode (second electrode) 6 is arranged so as to face the fuel electrode 3 via the intermediate layer 9. The intermediate layer 9 is formed on the solid electrolyte layer 4 on which the oxygen electrode 6 is formed. Although not shown, the intermediate layer 9 may be provided in the cylindrical cell 100 and the horizontal stripe cell 200 shown in FIG. 1 in the same manner.

An interconnector layer 8 made of conductive ceramics having a gas blocking property is formed on the other flat surface n (the other main surface: the upper surface) on which the oxygen poles 6 are not laminated.

That is, in the cell 300, the fuel electrode 3 and the solid electrolyte layer 4 are formed from one flat surface (one side main surface: lower surface) via the arcuate surfaces m at both ends and the other flat surface n (the other side main surface: lower surface). It is formed up to the upper surface), and both ends of the interconnector layer 8 are laminated and joined to both ends of the solid electrolyte layer 4. The solid electrolyte layer 4 is provided on the entire surface of the main surface on one side.

Further, the support 1 is surrounded by the solid electrolyte layer 4 having a gas blocking property and the interconnector layer 8, so that the fuel gas flowing inside does not leak to the outside. In other words, the solid electrolyte layer 4 and the interconnector layer 8 form an elliptical tubular body having a gas blocking property, and the inside of the elliptical tubular body serves as a fuel gas flow path and is supplied to the fuel electrode 3. The fuel gas and the oxygen-containing gas supplied to the oxygen electrode 6 are blocked by an elliptical tubular body.

More specifically, as shown in FIG. 2C, the oxygen pole 6 having a rectangular planar shape is formed except for the upper and lower ends of the support 1, while the interconnector layer 8 is formed. Although not shown, the support 1 is formed from the upper end to the lower end, and the left and right end portions thereof are joined to the surfaces of the left and right end portions of the solid electrolyte layer 4. As will be described later, the interconnector layer 8 may not be provided at the lower end portion.

Here, in the cell 300, the portion where the fuel electrode 3 and the oxygen electrode 6 face each other via the solid electrolyte layer 4 functions as the element portion a for power generation. That is, oxygen-containing gas such as air is passed outside the oxygen electrode 6, and fuel gas (hydrogen-containing gas) is passed through the fuel gas passage 2 in the support 1 to generate power by heating to a predetermined operating temperature. Then, the current generated by such power generation is collected via the interconnector layer 8 provided on the support 1.

Even in this hollow flat plate type cell 300, as shown in FIGS. 2 (b) and 2 (c), the solid electrolyte layer 4 has a portion where the oxygen poles 6 do not overlap. For example, one end (lower end) of the cell 300. In the examples shown in FIGS. 2 (b) and 2 (c), the first layer 7 described later is provided at one end of the portion where the oxygen poles 6 do not overlap.

Hereinafter, each member constituting the cell of the present embodiment will be described with reference to the cell 300. In cells 100 and 200, the same materials as below can be used unless otherwise specified.

Since the support 1 is required to be gas permeable in order to allow the fuel gas to permeate to the fuel electrode 3 and to be conductive in order to collect electricity through the interconnector layer 8, for example, It is preferably formed of Ni and / or NiO and an inorganic oxide, such as a particular rare earth element oxide.

The specific rare earth element oxide is used to bring the coefficient of thermal expansion of the support 1 close to the coefficient of thermal expansion of the solid electrolyte layer 4, and is used to bring the coefficient of thermal expansion of the support 1 close to that of Y, Lu, Yb, Tm, Er, Ho, Dy, and so on. Rare earth element oxides containing at least one element selected from the group consisting of Gd, Sm and Pr can be used in combination with Ni and / or NiO. Specific examples of such rare earth _{oxide, 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, Gd 2 O ₃ , Sm ₂ O ₃ , Pr ₂ O ₃ can be exemplified, and there is almost no solid dissolution or reaction with Ni and / or NiO, and the thermal expansion coefficient is about the same as that of the solid electrolyte layer 4. and from the point that it is _{inexpensive, Y 2 O 3, Yb 2} O 3 it is preferred.

Further, in the present embodiment, when the support 1 is made into the conductive support 1, Ni and / / Ni and / / are in that good conductivity is maintained and the coefficient of thermal expansion is approximated to that of the solid electrolyte layer 4. Alternatively, it is preferably present in a volume ratio of NiO: rare earth element oxide = 35: 65-65: 35.

Further, when the support 1 is used as the insulating support 1, it is preferably formed of, for example, Mg oxide (MgO), Ni and / or NiO, and a specific rare earth oxide. As the rare earth element oxide, the same one as described above can be used. Further, MgO is preferably 70 to 80% by volume, rare earth element oxide is 10 to 20% by volume, and Ni and / or NiO is 10 to 25% by volume, preferably having a resistivity of 10Ω · cm or more as a whole.

The support 1 may contain other metal components and oxide components as long as the required properties are not impaired.

Further, since the support 1 needs to have fuel gas permeability, it is porous, and the porosity is usually preferably in the range of 30% or more, particularly 35 to 50%. .. Further, the conductivity of the support 1 is preferably 300 S / cm or more, particularly preferably 440 S / cm or more.

The length of the flat surface n of the support 1 (the length of the support 1 in the width direction W) is, for example, 15 to 35 mm, and the length of the arcuate surface m (the length of the arc) is 2 to 8 mm. Yes, the thickness of the support 1 (thickness between flat surfaces n) is 1.5 to 5 mm. The length of the support 1 is, for example, 100 to 300 mm.

The fuel electrode 3 causes an electrode reaction and can be formed of a porous conductive ceramic known per se. For example, it can be formed from ZrO _{2 in which a} rare earth element oxide is dissolved or CeO _{2 in} which a rare earth element oxide is dissolved, and Ni and / or NiO. As the rare earth element, the rare earth element exemplified in the support 1 can be used, and for example, it can be formed from ZrO ₂ (YSZ) in which Y ₂ O ₃ is dissolved and Ni and / or NiO.

The content of ZrO _{2 in which the} rare earth element oxide is solid-dissolved or CeO ₂ in which the rare earth element oxide is solid-dissolved in the fuel electrode 3 is preferably in the range of 35 to 65% by volume, and Ni or NiO. The content of is preferably 65 to 35% by volume. Further, the porosity of the fuel electrode 3 is preferably in the range of 15% or more, particularly 20 to 40%, and the thickness thereof is preferably 1 to 30 μm.

Further, since the fuel pole 3 may be formed at a position facing the oxygen pole 6, for example, the fuel pole 3 is formed only on the flat surface n on the lower side of the support 1 on which the oxygen pole 6 is provided. May be. That is, the fuel pole 3 is provided only on the flat surface n on the lower side of the support 1, and the solid electrolyte layer 4 is the surface of the fuel pole 3, the bi-arc-shaped surface m of the support 1, and the support on which the fuel pole 3 is not formed. It may have a structure formed on the flat surface n on the upper side of the body 1.

As described above, the solid electrolyte layer 4 preferably contains 3 to 15 mol% of partially stabilized or stabilized ZrO _{2 in} which rare earth element oxides such as Y, Sc, and Yb are dissolved as a main component. Further, as a rare earth element, Y is preferable because it is inexpensive. The solid electrolyte layer 4, partially stabilized or is not limited to ceramics composed of stabilized ZrO _2, conventionally, known, for example, Gd, ceria or a rare earth element in solid solution, such as Sm, lanthanum gallate DOO Of course, it may be a solid electrolyte layer of the system.

Between the solid electrolyte layer 4 and the oxygen electrode 6 described later, the bond between the solid electrolyte layer 4 and the oxygen electrode 6 is strengthened, and the components of the solid electrolyte layer 4 and the components of the oxygen electrode 6 react with each other to generate electricity. The intermediate layer 9 is formed for the purpose of suppressing the formation of a reaction layer having high resistance.

The intermediate layer 9 is made of a CeO _2- based sintered body containing a rare earth element oxide other than Ce, and is, for example, (CeO ₂ ) _1-x (REO _1.5 ) _x (RE in the formula). Is at least one of Sm, Y, Yb, and Gd, and x preferably has a composition represented by 0 <x≤0.3). Furthermore, from the viewpoint of reducing electrical resistance, it is preferable to use Sm or Gd as RE, and for example, it is preferably composed of CeO ₂ in which 10 to 20 mol% of SmO _1.5 or GdO _1.5 is dissolved. .. The intermediate layer 9 may have a two-layer structure.

The oxygen electrode 6 is preferably formed of conductive ceramics made of so-called ABO ₃ type perovskite type oxide. The perovskite-type oxide is at least one of a transition metal perovskite-type oxide containing La, particularly a LaMnO _3- based oxide in which Sr and La coexist at the A site, a LaFeO _3- based oxide, and a LaCoO _3- based oxide. , and particularly preferably LaCoO ₃ type oxide from the viewpoint of high electrical conductivity at operating temperatures of about 600 to 1000 ° C.. In the above-mentioned perovskite-type oxide, Fe and Mn may be present together with Co at the B site.

Further, the oxygen electrode 6 needs to have gas permeability, and therefore, the conductive ceramics (perovskite type oxide) forming the oxygen electrode 6 has a porosity of 20% or more, particularly in the range of 30 to 50%. It is preferable to be in. Further, the thickness of the oxygen electrode 6 is preferably 30 to 100 μm from the viewpoint of current collecting property.

The interconnector layer 8 is formed of conductive ceramics. Since it comes into contact with fuel gas (hydrogen-containing gas) and oxygen-containing gas, it is necessary to have reduction resistance and oxidation resistance. Therefore, for example, a lanthanum chromite-based perovskite-type oxide (LaCrO _3- based oxide) is used as the conductive ceramics having reduction resistance and oxidation resistance, and in particular, the heat of the support 1 and the solid electrolyte layer 4 is used. for the purpose of close to expansion coefficient, LaCrMgO ₃ based oxide Mg is present in the B site is used. The material of the interconnector layer 8 may be any conductive ceramic, and is not particularly limited.

The thickness of the interconnector layer 8 is preferably 10 to 60 μm from the viewpoint of preventing gas leakage and electrical resistance. Within this range, gas leakage can be prevented and electrical resistance can be reduced.

Then, in the cells 100, 200, and 300 of the present embodiment shown in FIGS. 1 and 2, the first layer 7 composed of a large number of particles is provided on the portion of the solid electrolyte layer 4 where the oxygen electrodes do not overlap. ing.

As shown in the example shown in FIG. 2C, the first layer 7 is provided up to the lower end of the cell 300. The lower end of the cell 300 is a root portion joined to the gas tank, as will be described later. Therefore, the root portion of the cell 300 can be strengthened, and the occurrence of cracks and the like can be suppressed.

The material constituting the first layer 7 can be used, for example, zirconia oxide containing a rare earth element oxide, ceria based oxide containing a rare earth element oxide, lanthanum gallate bets based oxide and the like.

Here, for example, when the material constituting the solid electrolyte layer 4 contains ZrO ₂ containing a rare earth element oxide as a main component, the first layer 7 contains a rare earth element oxide more than the solid electrolyte layer 4. Is preferably small. On the other hand, for example, when the material constituting the solid electrolyte layer 4 contains CeO ₂ containing a rare earth element oxide as a main component, the first layer 7 contains a rare earth element oxide more than the solid electrolyte layer 4. Is preferable. With such a configuration, the strength of the first layer 7 can be made higher than that of the solid electrolyte layer 4, and the solid electrolyte layer 4 is prevented from being damaged by the impact applied to the solid electrolyte layer 4. In addition, since the components are similar to those of the solid electrolyte layer 4, the bonding strength between the solid electrolyte layer 7 and the first layer 7 can be increased. Here, the main component refers to a component that occupies 90% by volume or more of the elements constituting the solid electrolyte layer 4 and the first layer 7.

In particular, it is desirable that the solid electrolyte layer 4 contains partially stabilized zirconia, for example, ZrO _{2 in} which 7 to 9 mol% of Y ₂ O ₃ is solid-dissolved, as a main component in terms of improving power generation performance. Further, it is desirable that the first layer 7 contains ZrO ₂ as a main component, which is a solid solution of Y ₂ O ₃ having a rare earth element oxide content of, for example, 3 to 5 mol%.

Here, the width of the first layer 7 (the length of the cell 300 in the width direction W) can be appropriately set, but can be, for example, the same as the width of the flat surface n of the support 1. On the other hand, the length of the first layer 7 depends on the length of the cell 300, but from the viewpoint of improving the strength of the cell 300 while securing the power generation region, for example, 3 to 10 with respect to the length of the support 2. It can be about%.

Further, the thickness of the first layer 7 is preferably thicker than the thickness of the solid electrolyte layer 4 from the viewpoint of further improving the strength. Therefore, for example, the thickness of the first layer 7 can be 30 to 100 μm, whereas the thickness of the solid electrolyte layer 4 is 30 μm or less.

By the way, for example, the conductive support 1 containing a large amount of Ni expands and contracts to a large extent when exposed to a reducing atmosphere, and therefore, when the cell 300 is exposed to a reducing atmosphere, the cell 300 is large. Stress acts, and a large stress is also applied to the first layer 7. Further, when the lower end portion is fixed to the gas tank described later with a heat-resistant sealing material or the like, a large stress acts on the first layer 7 as the sealing material expands or contracts. As a result, in the first layer 7, cracks and the like may occur due to these stresses, and the protective function of the solid electrolyte layer 4 may be impaired.

Therefore, in the present embodiment, in the first layer 7, the average particle size of the surface layer portion is larger than that of the inside. With this configuration, the ductility can be improved by the structure having a large average particle size in the surface layer portion while maintaining the strength by the structure having a small average particle size inside. Therefore, even when the first layer 7 is deformed by the deformation of the cells 100, 200, and 300, the stress of deformation can be relaxed on the surface of the first layer 7 and the occurrence of cracks can be suppressed. Therefore, the long-term reliability of cells 100, 200, and 300 can be improved.

The surface layer portion means particles exposed on the surface of the first layer 7. Further, the inside means particles that are not exposed on the surface of the first layer 7. Although it is described as "exposed to the surface", the surface here may be the outermost surface of the first layer 7, and it is not always necessary to be exposed to the outside air. Therefore, for example, when another member is provided on the first layer 7, the surface layer portion exists at the boundary with the other member. Element mapping or the like can be used to specify the boundary with another member.

The particles exposed on the surface of the first layer 7 are referred to as the first particle group, and the particles that are in contact with the first particle group and are located on the inner side are referred to as the second particle group and are in contact with the second particle group. When the particles located on the inner side are defined as the third particle group, the particles having a particle size of 2 μm or more among the second particle group and the third particle group may be regarded as the above-mentioned surface layer particles. It shall be. Moreover, such particles may be interpreted by excluding them from the internal particles.

Further, the surface layer portion of the first layer 7 preferably has an average particle size of 2 to 6 μm. When it is 2 μm or more, the ductility is improved in the surface layer portion, so that the stress of deformation can be relaxed on the surface of the first layer 7 and the occurrence of cracks can be suppressed. When it is 6 μm or less, it is possible to prevent the average particle size from becoming too large in the surface layer portion, so that it is possible to suppress a decrease in strength.

In order to obtain the average particle size of the surface layer portion, first, an SEM image of a cross section in the thickness direction of the first layer 7 magnified by SEM at a magnification of 10000 times is acquired. Next, the measurement line of line profiling is drawn so as to cross the 10 particles of the surface layer portion on the cross-sectional photograph, and the average particle size is calculated.

Further, the average particle size inside the first layer 7 is preferably 0.2 to 1.5 μm. When it is 0.2 μm or more, the average particle size inside is not too small and the ductility is not too small. Therefore, it is possible to prevent the difference in ductility from the surface layer portion from becoming too large, and the difference between the surface layer portion and the inside can be suppressed. It is possible to suppress the occurrence of cracks at the boundary between the two. Further, when it is 1.5 μm or less, the average particle size inside is sufficiently small, so that the strength inside the first layer 7 can be improved. The average particle size inside may be obtained by the same method as the method for calculating the average particle size of the surface layer portion.

An example of the method for producing the cell 300 of the present embodiment described above will be described.

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 obtained by calcining the support molded body 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, an organic binder and a solvent are mixed with the mixed powder to prepare a slurry for fuel electrode.

Then, toluene, a binder powder (hereinafter, a polymer rather than the binder powder attached to the ZrO ₂ powder, for example, an acrylic resin), a commercially available dispersant, etc. are added to the ZrO ₂ powder in which the rare earth element oxide is solid-dissolved, and the slurry is added. A sheet-shaped solid electrolyte layer molded body is produced by molding the powdered product by a method such as a doctor blade.

A fuel electrode slurry is applied onto the obtained sheet-shaped solid electrolyte layer molded body and dried to form a fuel electrode molded body to form a sheet-shaped laminated molded body. The surface of the sheet-shaped laminated molded body in which the fuel electrode molded body and the solid electrolyte layer molded body are laminated is laminated on the conductive support molded body to form the molded body.

Next, the above-mentioned laminated molded product is calcined at 800 to 1200 ° C. for 2 to 6 hours. Thereafter, the solid electrolyte molded body (the calcined body), for the first layer with the dissolved amount is small ZrO ₂ powder and the binder powder, and the like of rare earth oxide than the slurry for solid electrolyte layer formed body above Slurry is prepared, and this slurry is applied in the shape shown in FIG. 2 and dried.

Here, as described above, in order to make the average particle size of the surface layer portion larger than that inside the first layer, after applying the slurry to be the first layer, a material different from that of the first layer is applied to the slurry. The first layer may be sintered by adding a small amount to the surface of the above.

Further, as another means, the first layer may be sintered as described later in a state where a substrate made of a material different from the first layer is brought into contact with the surface of the slurry to be the first layer. ..

The different material is zirconia-based oxide containing a rare earth element oxide, ceria based oxide containing a rare earth element oxide may be a lanthanum gallate preparative based oxide and the like. For example, when the material of the slurry to be the first layer is ZrO ₂ (YSZ) in which Y ₂ O ₃ is dissolved, the material to be added to the surface is CeO ₂ (GDC) in which Gd ₂ O ₃ is dissolved. All you need is.

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

Subsequently, an intermediate layer to be arranged between the solid electrolyte layer 4 and the oxygen electrode 6 is formed. For example, the CeO ₂ powder in which GdO _1.5 is dissolved is heat-treated at 800 to 900 ° C. for 2 to 6 hours to prepare a raw material powder for an intermediate layer molded product. Toluene is added as a solvent to this raw material powder to prepare a slurry for an intermediate layer, and this slurry is applied onto a solid electrolyte layer molded product to prepare an intermediate layer molded product.

After that, the slurry for the interconnector layer is applied so that both ends of the molded body for the interconnector layer are laminated on both ends of the solid electrolyte molded body (temporary baked body) to prepare the laminated molded body. A slurry for the interconnector layer is prepared, a sheet for the interconnector layer is prepared, and the sheet for the interconnector layer is laminated so that both ends of the sheet for the interconnector layer are laminated on both ends of the solid electrolyte molded body. Can also be laminated to produce a laminated molded body.

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. As described above, a small amount of a material different from the slurry is added to the surface of the slurry to be the first layer, or a substrate made of a material different from the first layer is brought into contact with the surface of the slurry to be the first layer. When co-fired in this state, the different materials diffuse into the particles on the surface layer of the slurry, and these particles cause grain growth. As a result, the average particle size of the surface layer portion of the first layer becomes large. In addition, in order to increase the average particle size of the surface layer portion by grain growth during firing, it is necessary to have a high temperature as in the case of this simultaneous firing.

Further, the oxygen electrode material (e.g., LaCoO ₃ based oxide powder), coated on the intermediate layer by dipping a slurry containing a solvent and Zoana agent, at 1000 to 1300 ° C., by baking for 2 to 6 hours , The cell 300 of the present embodiment having the structure shown in FIG. 2 can be manufactured.

FIG. 3 shows an example of a cell stack device configured by electrically connecting a plurality of the above-mentioned cells 300 in series via a conductive member 13, and FIG. 3A shows a cell stack device. A schematic side view, (b) is a partially enlarged cross-sectional view of the cell stack device of (a), and is an excerpt of a portion surrounded by a broken line shown in (a). In addition, in (b), the portion corresponding to the portion surrounded by the broken line indicated by (a) is indicated by an arrow, and in the cell 300 indicated by (b), the above-mentioned intermediate layer 9 and the like are shown. Some members of are omitted.

In the cell stack device, each cell 300 is arranged via a conductive member 13 to form a cell stack 12, and the lower end of each cell 300 is for supplying fuel gas to the cell 300. It is fixed to the gas tank 16 by an insulating joining material 17 such as a glass sealing material. Further, the cell stack 12 is sandwiched from both ends of the cell 300 in the arrangement direction by the elastically deformable end conductive member 14 whose lower end is fixed to the gas tank 16.

Further, in the end conductive member 14 shown in FIG. 3, a current drawing portion for drawing a current generated by power generation of the cell stack 12 (cell 300) in a shape extending outward along the arrangement direction of the cells 300. 15 is provided.

FIG. 4 shows a fixed structure of the cell 300 to the gas tank 16. The lower end of the cell 300 is inserted into an opening formed on the upper surface of the gas tank 10 and fixed by a joining material 17 such as a glass sealing material.

FIG. 4 shows an example in which the cell 300 of the type shown in FIG. 2 is fixed to the gas tank 16. In FIG. 4, the lower end portion of the first layer 7 is embedded in a joining material 17 such as a glass sealing material, whereby the portion joined by the joining material 17 of the cell 300 can be reinforced, and the lower end portion of the cell 300 can be reinforced. Here, in addition to the reduction expansion and contraction of the support 1, stress is generated at the lower end of the cell 300 due to the difference in the materials constituting the gas tank 16, the cell 300, and the bonding material 17 made of a heat-resistant alloy, and the first
Although cracks and the like may occur in the layer 7, since the average particle size of the surface layer portion of the first layer 7 is larger than that of the inside, the generation of cracks can be suppressed in the first layer 7. Therefore, the cell stack device with improved long-term reliability can be obtained.

FIG. 5 is an external perspective view showing an example of a fuel cell module 18 which is a module in which a cell stack device is stored in a storage container, and is a cell stack shown in FIG. 4 inside a rectangular parallelepiped storage container 19. It is configured to house the device.

In addition, in order to obtain the fuel gas used in the cell 300, a reformer 20 for reforming a raw fuel such as natural gas or kerosene to generate a fuel gas is arranged above the cell stack 12. .. 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 fuel gas passage 2 provided inside the cell 300 via the gas tank 16.

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 and the reformer 20 housed inside are taken out rearward. In the fuel cell module 18 shown in FIG. 5, the cell stack device can be slid and stored in the storage container 19. The cell stack device may include the reformer 20.

Further, the oxygen-containing gas introduction member 22 provided inside the storage container 19 is arranged between the pair of cell stacks 12 juxtaposed in the gas tank 16 in FIG. 5, and the oxygen-containing gas flows into the flow of the fuel gas. At the same time, the oxygen-containing gas is supplied to the lower end portion of the cell 300 so that the side of the cell 300 flows from the lower end portion to the upper end portion. Then, the temperature of the cell 300 can be raised by reacting the fuel gas discharged from the fuel gas passage 2 of the cell 300 with the oxygen-containing gas and burning it on the upper end side of the cell 300, and the cell stack device can be used. You can start up faster. Further, a reformer arranged above the cell 300 (cell stack 12) by burning the fuel gas and the oxygen-containing gas discharged from the gas passage 2 of the cell 300 on the upper end side of the cell 300. 20 can be warmed. As a result, the reformer 20 can efficiently carry out the reforming reaction.

Further, in the fuel cell module 18 of the present embodiment, since the cell stack device using the cell 300 described above is stored in the storage container 19, the fuel cell module 18 having improved long-term reliability can be obtained. ..

FIG. 6 is a perspective view showing an example of a fuel cell device which is a module storage device in which the fuel cell module 18 shown in FIG. 5 and an auxiliary machine for operating the cell stack device are housed in an outer case. is there. In FIG. 6, a part of the configuration is omitted.

In the fuel cell device 23 shown in FIG. 6, the inside of the exterior case composed of the support column 24 and the exterior plate 25 is vertically divided by a partition plate 26, and the upper side thereof is a module storage chamber for accommodating the fuel cell module 18 described above. 27, and the lower side is configured as an auxiliary equipment storage chamber 28 for accommodating auxiliary equipment for operating the fuel cell module 18. The auxiliary machines to be stored in the auxiliary machine storage chamber 28 are omitted.

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 fuel cell device 23, as described above, the fuel cell device 18 having improved reliability is configured by accommodating the fuel cell module 18 capable of improving reliability in the module storage chamber 27. It can be 23.

In addition to the above example, for example, a cell in which an oxygen electrode 6, a solid electrolyte layer 4, and a fuel electrode 3 are arranged on a support may be used.

Further, in the above embodiment, the fuel cell, the cell stack device, the fuel cell module, and the fuel cell device have been described, but the present invention is not limited to this, and water vapor (water) is applied to the cell by applying water vapor and voltage. ) Is electrolyzed to generate hydrogen and oxygen (O ₂ ), which can also be applied to cells (electrolytic cells, SOCC) and modules and module storage devices equipped with these cells.

First, mixed with NiO powder having an average particle diameter of 0.5 [mu] m, the _Y 2 _{O 3} powder having an average particle diameter of 0.9 .mu.m, and molding the kneaded material prepared with an organic binder and a solvent at an extrusion molding method, dried, A conductive support molded body was prepared by degreasing. Support compacts, volume ratio after reduction, NiO is 48 _vol%, Y 2 _{O 3} was 52 vol%.

Next, a slurry obtained by mixing a binder powder and a solvent with ZrO ₂ powder (solid electrolyte layer raw material powder) having a particle size of 0.8 μm by the microtrack method in which 8 mol% of Y ₂ O ₃ is solid-dissolved. Was used to prepare a sheet for the solid electrolyte layer by the doctor blade method.

The slurry for forming the intermediate layer molded product contains isopropyl alcohol (isopropyl alcohol) using a composite oxide containing 90 mol% of CeO ₂ and 10 mol% of rare earth element oxides (GdO _1.5 , SmO _1.5 ) as a solvent. It was crushed with a vibration mill or a ball mill using IPA), calcined at 900 ° C. for 4 hours, and then crushed again with a ball mill to adjust the degree of aggregation of ceramic particles. And a solvent were added and mixed to prepare the mixture.

Next, a fuel electrode slurry was prepared by mixing NiO powder having an average particle size of 0.5 μm, ZrO ₂ powder in which Y ₂ O ₃ was dissolved, an organic binder, and a solvent, and screen printing was performed on a sheet for a solid electrolyte layer. And dried to form a fuel electrode molded body.

A sheet-shaped laminated molded body in which a fuel electrode molded body was formed on a sheet for a solid electrolyte layer was laminated at a predetermined position of a support molded body with the surface on the fuel electrode molded body side inside.

Subsequently, the laminated molded body in which the above-mentioned molded bodies were laminated was calcined at 1000 ° C. for 3 hours. The slurry constituting the first layer was applied to the calcined body of the solid electrolyte in the shape shown in FIG. 2 and dried. The slurry constituting the first layer is, for example, a slurry containing ZrO ₂ powder in which 4 mol% of Y ₂ O ₃ is solid-solved. In addition, CeO in which Gd ₂ O ₃ is dissolved on the surface of this slurry.
₂ was added in a small amount.

After that, the slurry for forming the intermediate layer molded body was applied to the upper surface of the solid electrolyte calcined body by a screen printing method and dried to form the intermediate layer molded body.

Subsequently, a slurry for an interconnector layer was prepared by mixing La (Mg _0.3 Cr _0.7 ) _0.96 O ₃ having an average particle size of 0.7 μm with an organic binder and a solvent. The prepared slurry for the interconnector layer was applied to a portion of the support where the fuel electrode (and the solid electrolyte layer) was not formed (the portion where the support was exposed).

Next, the above-mentioned laminated molded product was debindered and simultaneously fired at 1450 ° C. for 2 hours in an oxygen-containing atmosphere.

Next, a mixed solution of La _0.6 Sr _0.4 Co _0.2 Fe _0.8 O ₃ powder having an average particle size of 2 μm and isopropyl alcohol was prepared and sprayed on the surface of the intermediate layer on the upper surface of the solid electrolyte. It was applied to form an oxygen electrode molded body and baked at 1100 ° C. for 4 hours to form an oxygen electrode to prepare a cell having the first layer 7 shown in FIG.

The size of the produced cell is 25 mm × 200 mm, the thickness of the support (thickness between flat surfaces n) is 2 mm, the open porosity is 35%, the thickness of the fuel electrode is 10 μm, the open porosity is 24%, and the solid electrolyte. The thickness of the layer was 20 μm, the thickness of the oxygen electrode was 50 μm, the open porosity was 40%, and the thickness of the interconnector layer was 40 μm. The thickness of the first layer 7 was 80 μm.

As shown in FIG. 4, the lower end of the cell stack, in which the seven cells 300 produced are electrically connected via a current collecting member, is inserted into the opening of the gas tank, and a bonding material made of crystallized glass is inserted. A cell stack device was manufactured by joining and fixing at 17. In this case, the upper end of the first layer 7 was exposed 5 mm upward from the end of the bonding material 17.

By the method as described above, the sample No. 1 to 10 cell stack devices were manufactured.

Here, the sample No. In the first layers 1 to 10, as shown in Table 1, the average particle size of the ZrO ₂ powder in which Y ₂ O ₃ was dissolved, the amount of CeO ₂ in which Gd ₂ O ₃ was dissolved, and the like were adjusted. The average particle size of the surface layer and the inside of the first layer was controlled.

Hydrogen gas was supplied into the gas tank of these cell stacking devices, hydrogen gas was allowed to flow inside the cell, and the support and fuel electrode were reduced and cooled at 850 ° C. for 10 hours.

In order to obtain the average particle size of the surface layer portion and the inside, after the reduction treatment, first, an SEM image of a cross section in the thickness direction of the first layer magnified by SEM at a magnification of 10000 times was obtained. Next, the measurement line of line profiling was drawn so as to cross 10 particles each on the surface layer portion and inside on the cross-sectional photograph, and the average particle size was calculated.

In addition, the presence or absence of cracks in the first layer after the reduction treatment was visually confirmed, and the number of cells in which cracks were generated in the first layer in the stack of each sample was counted. The results are shown in Table 1. ⊚, ◯, Δ, and × mean that the number of cells in which cracks have occurred in the first layer is 0, 1-2, 3-4, and 5-6, respectively.

As is clear from Table 1, the sample No. In No. 1, the number of cells in which cracks occurred in the first layer was large. This is because in the first layer, the average particle size of the surface layer portion was smaller than that of the inside.

In addition, sample No. In 2 and 10, sample No. Compared with 1, the number of cells in which cracks occurred in the first layer was smaller. This is because in the first layer, the average particle size of the surface layer portion was larger than that of the inside.

In addition, sample No. In 3 and 9, sample No. Compared with 2 and 10, the number of cells in which cracks occurred in the first layer was small. This is because the average particle size of the surface layer portion of the first layer was 2 to 6 μm.

In addition, sample No. In Nos. 4 to 8, sample No. Compared with 3 and 9, the number of cells in which cracks occurred in the first layer was small. This is because the average particle size inside the first layer was 0.2 to 1.5 μm.

1: Support 2: Fuel gas passage 3: First electrode (fuel electrode)
4: Solid electrolyte layer 6: Second electrode (oxygen electrode)
7: First layer 8: Interconnector layer 18: Fuel cell module 23: Fuel cell device a: Element unit

Claims (7)

The element portion in which the first electrode, the solid electrolyte layer, and the second electrode are laminated in this order is provided.
The solid electrolyte layer has a first portion where the second electrode does not overlap, and the solid electrolyte layer has a first portion.
A first layer composed of a large number of particles and thicker than the solid electrolyte layer is provided at least in a part of the first portion.
The particles are one of a zirconia-based oxide containing a rare earth element oxide, a ceria-based oxide containing a rare earth element oxide, and a lanthanum gallate-based oxide.
In the first layer, the average particle diameter of the surface layer portion is larger than the average particle diameter of the inner, cell. The average particle diameter of the surface layer portion is 2-6 [mu] m, the cell according to claim 1. The average particle diameter of the inner is 0.2 and 1.5 .mu.m, the cell according to claim 1 or claim 2. Together comprising a plurality including a cell according to any one of claims 1 to 3, formed by electrically connecting a plurality of cells, the cell stack device. At least a part of the first portion of the plurality of cells is fixed with a bonding material, and the plurality of cells further include a manifold for supplying a reaction gas to the plurality of cells.
At least a portion having the first layer, the surface layer portion exists at the boundary between the bonding material, the cell stack device according to claim 4 between the bonding material and the first portion. The storage container, formed by accommodating the cell stack device according to claim 4 or claim 5, module. In an outer casing, constituted by housing a module according to claim 6, the auxiliary machine for performing the operation of the module, the module accommodation device.

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