JP5198108B2 - Horizontally-striped solid oxide fuel cell stack and fuel cell - Google Patents

Description

  The present invention relates to a horizontally-striped solid oxide fuel cell stack and a fuel cell in which a plurality of them are accommodated in a storage container.

  In recent years, as next-generation energy, various fuel cells have been proposed in which a horizontal stripe type fuel cell stack in which a plurality of fuel cells are electrically connected to the surface of an electrically insulating support is accommodated in a storage container. . As such fuel cells, various types such as solid polymer fuel cells, phosphoric acid fuel cells, molten carbonate fuel cells, solid oxide fuel cells are known. In particular, solid oxide fuel cells have high power generation efficiency and high operating temperatures of 700 ° C. to 1000 ° C., so that the power generation efficiency can be increased by effectively using the exhaust heat. Have research and development.

  FIG. 10 is an enlarged longitudinal sectional view showing a part of a solid oxide fuel cell stack including a plurality of conventionally known solid oxide fuel cells. This solid oxide fuel cell stack has a fuel electrode layer 23a as an inner electrode layer, a solid electrolyte layer 23b, and an air electrode layer 23c as an outer electrode layer on the surface of a cylindrical support 21 that is an electrical insulator. Are stacked in this order with a predetermined interval in the longitudinal direction G (up and down direction on the paper surface) of the support 21 of the solid oxide fuel cell 23 having a multilayer structure (hereinafter sometimes abbreviated as fuel cell). A plurality are formed and electrically connected (for example, see Patent Document 1). The fuel cell stack having such a shape is called a so-called “horizontal stripe type”.

  Adjacent fuel cells 23 are electrically connected in series by interconnectors 24 as inter-cell connecting members. That is, the fuel electrode layer 23 a of one fuel battery cell 23 and the air electrode layer 23 c of the other fuel battery cell 23 are electrically connected by the interconnector 24. Further, one or more gas flow paths 27 are formed along the longitudinal direction G of the support 21 inside the support 21.

  In the solid oxide fuel cell stack in which the fuel electrode layer 23a, the solid electrolyte layer 23b, and the air electrode layer 23c are laminated in this order on the support 21, the oxygen ion conductivity of the solid electrolyte layer 23b is 600 ° C. or higher. Therefore, at such a temperature, a gas (air) containing oxygen is caused to flow around the fuel battery cell 23, and a gas (fuel gas) containing hydrogen is caused to flow through the gas flow path 27. The difference in oxygen concentration between the fuel electrode layer 23a and the fuel electrode layer 23a increases, and a potential difference is generated between the air electrode layer 23c and the fuel electrode layer 23a.

  Due to this potential difference, oxygen ions move from the air electrode layer 23c to the fuel electrode layer 23a through the solid electrolyte layer 23b. The moved oxygen ions combine with hydrogen in the fuel electrode layer 23a to become water, and at the same time, electrons are generated in the fuel electrode layer 23a. That is, the electrode reaction of the following formula (1) occurs in the air electrode layer 23c, and the electrode reaction of the following formula (2) occurs in the fuel electrode layer 23a.

  Then, by electrically connecting the fuel electrode layer 23a and the air electrode layer 23c, electrons move from the fuel electrode layer 23a to the air electrode layer 23c, and an electromotive force is generated between the electrode layers. In this way, in the solid oxide fuel cell 23, by supplying oxygen (air) and hydrogen (fuel gas), the above reaction is continuously caused to generate an electromotive force to generate electric power.

In such a horizontal stripe type solid oxide fuel cell stack, an insulator is used as the support 21 to prevent electrical shorts between the fuel cells 23. As the support 21, for example, a solid solution of Ni and MgAl ₂ O ₄ (spinel) or a solid solution of Ni and MgO is used (for example, see Patent Documents 2 to 6). Further, the support 21 is required to efficiently supply the fuel gas flowing through the gas flow path 27 to the fuel electrode layer 23a and generate power efficiently.

  However, when the support 21 is configured to include Ni and MgO, an electrically insulating support molded body that becomes the support 21 by firing in the manufacturing process of the horizontal stripe solid oxide fuel cell stack is formed. When calcined at about 900 ° C. to 1200 ° C., the strength of the obtained support calcined body may be low. The support calcined body having low strength is difficult to handle, and the strength of the support 21 obtained by firing the support calcined body is also low. As a result, there is a problem that the horizontal stripe solid oxide fuel cell stack is damaged and the yield is lowered.

JP-A-10-3932 JP-A-5-82146 JP-A-6-203855 JP-A-8-222246 JP-A-9-73906 JP-A-9-139220

  An object of the present invention is to provide a horizontally striped solid oxide fuel cell stack and a fuel cell including a support having high strength and capable of generating power efficiently.

As a result of intensive studies to solve the above problems, the present inventors have found the following findings. That is, when the electrically insulating support is configured to include Ni, MgO, and Fe ₂ O _3, and the Fe ₂ O ₃ content is 0.2 mol% or less, The strength of the support is improved, the handling becomes good, the damage of the electrically insulating support can be suppressed, and the yield can be improved. Further, when the open porosity of the electrically insulating support is 30% or more, the gas flowing through the gas flow path can be efficiently supplied to the inner electrode layer, and power can be generated efficiently.

That is, the horizontally-striped solid oxide fuel cell stack of the present invention has a fuel cell formed by laminating an inner electrode layer, a solid electrolyte layer, and an outer electrode layer in this order. The inner electrode layer of one of the fuel battery cells is electrically connected to the outer electrode layer of the other fuel battery cell adjacent to the one fuel battery cell. The plurality of fuel cells are connected in series, and the support is configured to include Ni, MgO, and Fe ₂ O _3, and the content of Fe ₂ O ₃ Is 0.2 mol% or less with respect to the total amount of the support, and the open porosity is 30% or more.

  Further, in the horizontally-striped solid oxide fuel cell stack according to the present invention, the molar ratio of Ni to MgO constituting the support (Ni / MgO) is in the range of 0.15 to 0.25. Preferably, it can suppress that the front-end | tip part of a support body is damaged by this at the time of electric power generation.

  In the horizontally-striped solid oxide fuel cell stack of the present invention, the content of Ni constituting the electrically insulating support is preferably 10 to 20 mol% based on the total amount of the support. Reforming gas such as gas and methane gas can be sufficiently reformed.

  In the horizontally-striped solid oxide fuel cell stack of the present invention, the support is preferably formed into a hollow flat plate shape, which can increase the area of the fuel cell stacked on the support. Therefore, the number of cell stacks can be reduced.

  Since the fuel cell according to the present invention includes a plurality of the above-described fuel cell stacks in a storage container, the fuel cell can be improved in reliability.

According to the present invention, the electrically insulating support includes Ni, MgO, and Fe ₂ O _3, and the content of Fe ₂ O ₃ is 0.2 mol% or less. The strength of the body can be improved. Moreover, since the open porosity of the support is 30% or more, power can be generated by efficiently supplying the gas flowing in the gas flow path to the inner electrode layer.

  Hereinafter, an embodiment of a horizontal stripe type solid oxide fuel cell stack (hereinafter sometimes abbreviated as a cell stack) of the present invention will be described in detail with reference to the drawings. FIG. 1 is an enlarged longitudinal sectional view showing a part of a cell stack according to the present embodiment, and FIG. 2 is a lateral sectional view thereof.

  As shown in FIG. 1 and FIG. 2, a horizontally-striped solid oxide fuel cell stack (hereinafter sometimes abbreviated as “cell stack”) according to the present embodiment has a gas flow path 12 therein and an electric circuit. A plurality of fuel cells 13 are arranged in parallel at a predetermined interval on the surface of the insulating support 11.

  The fuel battery cell 13 is configured by sequentially laminating a fuel electrode layer 13a as an inner electrode layer, a solid electrolyte layer 13b, and an air electrode layer 13c as an outer electrode layer on the surface of the support 11 in this order. Adjacent fuel cells 13 are electrically connected by an interconnector 14 as an inter-cell connecting member. That is, the fuel electrode layer 13 a of one fuel cell 13 and the air electrode layer 13 c of the other fuel cell 13 are connected in series in the longitudinal direction of the support 11 by the interconnector 14. .

  In such a cell stack, a fuel gas containing hydrogen is caused to flow into the gas flow path 12 to expose the support 11 to a reducing atmosphere, and an oxygen-containing gas such as air is caused to flow on the surface of the air electrode layer 13c. By exposing the layer 13c to an oxidizing atmosphere, the electrode reaction represented by the above-described formulas (1) and (2) occurs in the fuel electrode layer 13a and the air electrode layer 13c, and a potential difference is generated between the two electrodes to generate power. Can do.

  The support 11 is formed in a hollow flat plate shape, and a plurality (six in FIG. 2) of gas flow paths 12 separated by a partition wall 11a are provided therein. By making the support 11 have a hollow plate shape, the area of the fuel cell 13 per volume of the support 11 can be increased, and the amount of power generation per volume of the cell stack can be increased. Therefore, the number and volume of cell stacks for obtaining the required power generation amount can be reduced. As a result, the structure is simplified, the assembly is simplified, and the reliability of the fuel cell (horizontal stripe solid oxide fuel cell stack) can be improved. Further, since the plurality of gas flow paths 12 are provided inside the support 11, the structural strength of the support 11 can be improved, and the mechanical strength of the cell stack can be increased.

  From the viewpoint of preventing an electrical short circuit with the fuel cell 13, the support 11 is usually preferably set in a range of an electric resistance value of 10 Ω · cm or more. The electric resistance value can be measured by a four-terminal method in which both terminals of voltage and current are connected to both ends of a prismatic sample piece.

  The support 11 has a pair of flat portions n and arc-shaped portions m connecting both ends thereof, and the major axis dimension in the cross section (corresponding to the distance between the arc-shaped portions m at both ends) is, for example, 15 mm to 50 mm, The minor axis dimension (corresponding to the distance between the pair of flat portions n) can be set in the range of 2 mm to 4 mm, for example.

Here, the support 11 in the present embodiment is configured to include Ni, MgO, and Fe ₂ O _3, and the content of Fe ₂ O ₃ is 0.2 mol% with respect to the total amount of the support 11. It is as follows. Ni can also be contained as NiO (NiO is usually reduced by hydrogen gas and present as Ni during power generation). Thereby, in the manufacturing process of a cell stack, when the support molded body is calcined at about 900 ° C. to 1200 ° C., the strength of the support 11 can be improved and the handling can be improved. Thereby, it can suppress that the support body 11 breaks, and can improve a yield.

On the other hand, if the support 11 does not contain Fe ₂ O ₃ , it is difficult to improve the strength of the support 11. Further, when the content of Fe ₂ O ₃ is more than 0.2 mol%, the strength of the support 11 is improved, but the open porosity of the support 11 described below is less than 30%, which is efficient. It cannot generate electricity.

  The open porosity of the support 11 in this embodiment is 30% or more. Thereby, the fuel gas which flows through the gas flow path 12 can be efficiently circulated to the surface of the fuel electrode layer 13a, the fuel utilization rate can be improved, and the power generation amount in the cell stack can be improved. Thereby, the number of cell stacks can be reduced in obtaining a predetermined power generation amount. In order to further improve the fuel utilization rate, the open porosity of the support 11 is more preferably 32% or more. The open porosity of the support 11 is preferably 45% or less. When the porosity of the support 11 is greater than 45%, the strength of the support 11 may decrease, and further, a cell stack in which the fuel cells 13 are arranged on the surface of the support 11 is used as a gas flow path. 12 is fixed to a manifold for supplying fuel gas or the like, cracks may occur on the lower end side (manifold side) of the cell stack (support 11). In particular, the open porosity of the support 11 is preferably 30 to 37%, more preferably 32 to 37%.

  The open porosity can be calculated according to the Archimedes method. The open porosity can be arbitrarily set, for example, by adjusting the amount of burned material added when producing the support molded body 51 described later.

  By the way, when a power generation test is performed using a fuel cell containing the cell stack as described above, the tip of the support 11 may be broken. This is because the strength of the support 11 is sufficient, but the oxygen-containing gas supplied to the outer peripheral portion of the cell stack tends to back-diffusion at the tip, so that the support 11 once exposed to the reducing atmosphere is reoxidized. It can be inferred that this causes the expansion of the volume due to the composition change between Ni and NiO constituting the support 11 and leads to the destruction of the tip.

  Therefore, in the cell stack of this embodiment, it is preferable that the ratio (Ni / MgO) of Ni to MgO constituting the support 11 is in the range of 0.15 to 0.25. Thereby, it is possible to suppress the destruction of the support 11 due to the volume change in the state of the environmental change from the reduction to the re-oxidation while maintaining the reforming ability of the support 11.

Moreover, it is preferable that the ratio of Ni constituting the support 11 is 10 to 20 mol% with respect to the total amount of the support 11. Thereby, reforming | reforming gas, such as city gas and methane gas, can fully be performed. The support 11 preferably further contains Y ₂ O ₃ for the purpose of matching the thermal expansion coefficient with members such as a fuel electrode layer 13a and a solid electrolyte layer 13b described later.

  The fuel cell 13 formed on the surface of the support 11 has a fuel electrode layer 13a as an inner electrode layer, a solid electrolyte layer 13b, and an air electrode layer 13c as an outer electrode layer on the surface of the support 11. The layers are sequentially stacked in this order. Adjacent fuel cells 13 are electrically connected by an interconnector 14. That is, the fuel electrode layer 13 a of one fuel cell 13 and the air electrode layer 13 c of the other fuel cell 13 are connected in series in the longitudinal direction of the support 11 by the interconnector 14. . Thereby, the power generation voltage per cell stack can be increased, and a high voltage can be obtained with a small number of fuel cells.

The fuel electrode layer 13a can be formed of, for example, a porous conductive cermet made of ZrO ₂ (stabilized zirconia) in which a rare earth element is dissolved and Ni. Moreover, the material of the solid electrolyte layer 13b described later can also be used. In the fuel electrode layer 13a, the blending ratio of the stabilized zirconia is preferably in the range of 35% by volume to 65% by volume with respect to the total amount of the fuel electrode layer 13a, and the blending ratio of Ni is calculated in terms of NiO in the fuel electrode layer 13a. The range of 35 volume%-65 volume% is preferable with respect to the total amount. In addition, the fuel electrode layer 13a preferably has an open porosity of, for example, 15% or more, more preferably in the range of 20% to 40%. It is preferable to be in a range of ˜100 μm.

The solid electrolyte layer 13b may be composed of a dense ceramic made of stabilized ZrO ₂ composed of ZrO ₂ which was a solid solution of a rare earth element or its oxide. Here, examples of the rare earth element to be dissolved include Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. From the viewpoint of being inexpensive, it is preferable to use Y, Yb, or Y ₂ O ₃ or Yb ₂ O ₃ which is an oxide thereof. More specifically, the solid electrolyte layer 13b includes stabilized ZrO ₂ (8 mol% Yttria Stabilized Zirconia, hereinafter referred to as “8YSZ”) in which 8 mol% Y is dissolved. Alternatively, a lanthanum gallate system (LaGaO ₃ system) having a shrinkage rate substantially equal to 8YSZ can be used.

  The thickness of the solid electrolyte layer 13b is preferably 10 μm to 100 μm, and the relative density (according to Archimedes method) is preferably set to 93% or more, more preferably 95% or more. Such a solid electrolyte layer 13b has a function as an electrolyte for bridging electrons between electrodes, and at the same time has a gas barrier property to prevent leakage of fuel gas or oxygen-containing gas (gas permeation). Yes.

The air electrode layer 13c is formed from conductive ceramics. Examples of the conductive ceramic include ABO ₃ type perovskite oxide. Examples of such perovskite oxides include transition metal perovskite oxides, preferably LaMnO ₃ -based oxides, LaFeO ₃ -based oxides, LaCoO ₃ -based oxides, etc., particularly transition metals having La at the A site. A type perovskite oxide can be used. From the viewpoint of high electrical conductivity at a relatively low temperature of about 600 ° C. to 1000 ° C., it is preferable to use a LaCoO ₃ -based oxide. In the perovskite oxide described above, La and Sr may coexist at the A site, and Fe, Co, and Mn may coexist at the B site.

  Such an air electrode layer 13c can cause the electrode reaction of the above-described formula (1). Moreover, it is preferable that the open porosity of the air electrode layer 13c is set in a range of, for example, 20% or more, and further 30% to 50%. By setting the open porosity of the air electrode layer 13c within this range, the air electrode layer 13c can have good gas permeability. Furthermore, by setting the thickness of the air electrode layer 13c to, for example, a range of 30 μm to 100 μm, the air electrode layer 13c can have good current collecting properties.

The interconnector 14 electrically connects the fuel electrode layer 13a of one fuel battery cell 13 and the air electrode layer 13c of the other fuel battery cell 13, and can be formed from conductive ceramics. Examples of such conductive ceramics include lanthanum chromite-based perovskite oxides (LaCrO ₃ -based oxides). Since the LaCrO ₃ oxide has good reduction resistance and oxidation resistance, corrosion and deterioration of the interconnector 14 can be effectively suppressed.

Further, the conductive ceramic forming the interconnector 14 is preferably set to have a relative density (Archimedes method) in a range of, for example, 93% or more, and more preferably 95% or more. By setting the relative density within this range, the conductive ceramic can be made dense, and the leakage of the fuel gas passing through the gas flow path 12 in the support 11 and the oxygen-containing gas passing through the outside of the air electrode layer 13c. Can be effectively suppressed. Further, by appropriately interposing a bonding layer such as Y ₂ O _{3 in} the connecting portion between the interconnector 14 and the solid electrolyte layer 13b, the sealing performance can be improved.

  In the embodiment described above, the fuel cell 13 formed on the surface of the support 11 has an example of a multilayer structure in which the inner electrode layer is the fuel electrode layer 13a and the outer electrode layer is the air electrode layer 13c. Although shown, the positional relationship between both electrode layers may be reversed. That is, the fuel cell 13 in which the air electrode layer 13c, the solid electrolyte layer 13b, and the fuel electrode layer 13a are sequentially laminated in this order can be disposed on the surface of the support 11. In this case, an oxygen-containing gas such as air is circulated in the gas flow path 12 of the support 11, and a fuel gas such as a hydrogen-containing gas is circulated on the surface of the fuel electrode layer 13a as the outer electrode layer.

  Next, a structure in which a plurality of horizontal stripe solid oxide fuel cell stacks described above are connected (hereinafter referred to as a bundle in the present specification) will be described with reference to FIG.

  FIG. 3 is an enlarged longitudinal sectional view showing an end portion (end portion of the cell stack) in a bundle in which a plurality (two) of the cell stacks described above are combined. As shown in FIG. 3, the cell stacks are electrically connected to each other via a current collecting member 19.

  That is, at the end portion of the cell stack, the inter-cell stack connecting member 15 is provided at the end portion of one cell stack and is electrically connected to the fuel electrode layer 13a of the fuel cell 13 constituting the one cell stack. . In addition, the inter-cell stack connecting member 15 is electrically connected to the air electrode layer 13 c of the other fuel cell 13 through the current collecting member 19 at the end of the other cell stack.

  As described above, since the cell stacks can be arranged densely by electrically connecting the plurality of cell stacks via the current collecting member 19, the volume of the cell stack per power generation amount can be reduced. Can do. Therefore, a small and highly efficient cell stack can be provided.

  The inter-cell stack connecting member 15 is not particularly limited as long as it electrically connects the fuel electrode layer 13a of one cell stack and the air electrode layer 13c of the other cell stack. For example, the interconnector 14 It can be formed from the same material.

  The current collecting member 19 is particularly limited as long as it is electrically connected to the air electrode layer 13c of the fuel cell constituting the other cell stack and electrically connects the interconnector 14 and the air electrode layer 13c. For example, it can be formed from a heat-resistant metal, conductive ceramics, or the like. Specifically, for example, a metal felt and / or a heat-resistant metal plate, an inorganic material, and the like are mentioned. From the viewpoint of heat resistance, oxidation resistance, and electrical conductivity, Pt, Ag, Ni alloy, and Fe—Cr steel alloy are used. It is preferable to use at least one kind.

  Further, by applying a conductive adhesive such as a paste containing a noble metal such as Ag or Pt to the connecting portion between the current collecting member 19, the inter-cell stack connecting member 15 and the air electrode layer 13c, the current collecting member The connection reliability of 19 can also be improved. When the fuel electrode layer 13a is formed as an external electrode layer, the current collecting member 19 can be formed from, for example, Ni felt. Moreover, as a conductive adhesive, the paste containing Ni metal can be illustrated.

  FIG. 4 is a longitudinal sectional view showing a bundle in which a plurality (three) of the cell stacks described above are combined. In FIG. 4, the fuel cell 13, the interconnector 14, and the inter-cell stack connecting member 15 are shown in a simplified manner.

  A current collecting member 19 is interposed between the inter-cell stack connecting member 15 at the end of one cell stack and the air electrode layer 13c at the end of the other cell stack, thereby supporting the support 11 of one cell stack. The fuel electrode layer 13a formed on the surface is electrically connected to the air electrode layer 13c of the other fuel battery cell via the inter-cell stack connecting member 15 and the current collecting member 19. In FIG. 4, the conductive member 20 is a member for taking out the electric power generated in the cell stack, whereby the electric power generated in the plurality of cell stacks can be easily drawn out.

  The fuel cell of the present invention is configured by storing a plurality of the above-described cell stacks in a storage container. Accordingly, since the cell stack can be densely arranged in the storage container, the volume of the fuel cell per power generation amount can be reduced, and a small and highly efficient fuel cell can be provided.

  The storage container is provided with an introduction pipe for introducing a fuel gas such as a hydrogen-containing gas and an oxygen-containing gas such as air from the outside into the storage container, and the fuel after being used by the power generation of the cell stack. It is preferable to have an exhaust part for exhausting gas or oxygen-containing gas (excess gas).

Next, a method of manufacturing the cell stack according to the above-described embodiment will be described with reference to FIGS.
First, a support molded body 51 as shown in FIG. 5 is produced. An example in which NiO is used as Ni as a constituent component of the support molded body 51 is shown. Examples of the material of the support molded body 51 include 10 to 20 mol% of NiO powder having an average particle diameter (D50) (hereinafter simply referred to as “average particle diameter”) of 0.1 to 10.0 μm, and an average particle diameter. 0.2 to 0.1 mol% Fe ₂ O ₃ having a diameter of 0.1 to 5 μm, 10 to 15 mol% of Y ₂ O ₃ powder having an average particle diameter of 0.5 to 5 μm, and MgO having an average particle diameter of 0.5 to 5 μm The powder is blended at a ratio of 65 to 80 mol% and mixed. The said ratio is a ratio with respect to the total amount of the support body molded body 51 (namely, the support body 11). The average particle diameter is a value obtained by measurement of particle size distribution using a laser diffraction scattering method.

  The mixed powder is mixed with a burned material, a cellulose organic binder, and a solvent composed of water and extruded to form a hollow flat plate having a gas flow passage 52 therein, as shown in FIG. The support body molded body 51 was prepared, and this was dried and calcined at 900 ° C. to 1200 ° C.

  Here, in order to set the open porosity of the support 11 to 30% or more, the burnout material is added at a ratio of 10 to 20% by weight with respect to the total amount of the support molded body 51 (that is, the support 11). Is preferred. The average particle size of the burned material is preferably 5 to 30 μm. An organic resin (for example, an acrylic resin, a polyethylene resin, or the like) can be used as the burnout material.

Next, a fuel electrode layer material and a solid electrolyte layer material are produced. For example, a NiO powder and a ZrO ₂ powder in which a rare earth element oxide such as Y ₂ O ₃ is dissolved are mixed, a burned-out material is added thereto, and an acrylic binder and toluene are mixed to form a slurry. The slurry is applied by a blade method and dried to produce a fuel electrode layer tape 53a having a thickness of 80 μm to 120 μm, as shown in FIG.

  Separately, 8YSZ is mixed with an acrylic binder and toluene to form a slurry, and the slurry is applied by a doctor blade method and dried. As shown in FIG. 6A, a solid electrolyte layer tape having a thickness of 10 μm to 50 μm. 53b is produced.

  Next, as shown in FIG. 6 (b), the fuel electrode layer tape 53a and the solid electrolyte layer tape 53b are overlapped so that the portions where they do not overlap each other have a width of 1 mm to 5 mm. And bonding as shown in FIG.

  Thereafter, as shown in FIG. 7A, the fuel electrode layer tape 53a and the solid electrolyte layer tape 53b bonded in FIG. 6C are calcined with the fuel electrode layer tape 53a side down. Affixed to the calcined body 51 in a horizontal stripe pattern. This is repeated, and a laminate of a plurality of fuel electrode layer tapes 53a and solid electrolyte layer tape 53b is attached to the surface of the support calcined body 51. At this time, the laminate of one fuel electrode layer tape 53a and the solid electrolyte layer tape 53b and the laminate of the other fuel electrode layer tape 53a and the solid electrolyte layer tape 53b are spaced from each other by a width of 3 mm to 20 mm. Deploy. Next, the support body molded body 51 is dried in a state where these laminates are adhered, and then calcined in a temperature range of 900 ° C. to 1300 ° C.

  Next, the interconnector molded body 54 and the inter-cell stack connecting member molded body 59 are formed. In addition, since the same material can be used for the interconnector 14 and the connection member 15 between cell stacks, both are formed in the same process here.

First, a dip slurry is prepared with lanthanum chromite (LaCrO ₃ ) and a polyvinyl alcohol (PVA) binder. Next, as shown in FIG. 7A, the portion (width 2 mm to 5 mm) excluding both ends of the solid electrolyte layer tape 53b is masked with a masking tape 61, and then as shown in FIG. 7B. Then, dip in the slurry for dip to form the interconnector molded body 54 and the inter-cell stack connecting member molded body 59. Thereafter, drying is performed, and then the masking tape 61 is removed as shown in FIG. Thereafter, firing is performed at 1450 ° C. to 1550 ° C. so that the interconnector 14 and the inter-cell stack connection member 15 cover the fuel electrode layer 13a and overlap the end portion of the solid electrolyte layer 13b with a width of about 2 mm to 5 mm. To do.

  Next, as shown in FIG. 8A, the entire surface of the inter-cell stack connecting member 15 and the entire surface of the interconnector 14 (however, one side opposite to the side where the interconnector 14 is connected to the fuel electrode layer 13a). Are masked with a masking tape 63.

Next, as shown in FIG. 8B, a slurry obtained by mixing lanthanum cobaltite (LaCoO ₃ ) and isopropyl alcohol is sprayed onto the masked laminate to form an air electrode layer molded body 53c having a thickness of 10 μm to 100 μm. . Thereafter, as shown in FIG. 8C, the masking tape 63 is removed, and heat treatment is performed at 1000 ° C. to 1200 ° C., whereby a horizontal stripe solid oxide fuel cell stack can be obtained.

  In the above description, each layer is laminated using tape lamination, dip and spray spraying, but the present invention may use only any lamination method. In particular, the drying process at the time of lamination is short, and it is preferable to laminate each layer by dipping from the viewpoint of shortening the process.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further in detail, this invention is not limited to a following example.

(Preparation of support molded body)
NiO powder having an average particle size of 0.5 to 1.0 μm, MgO powder having an average particle size of 0.8 to 3.0 μm, Fe ₂ O ₃ having an average particle size of 0.3 to ₂ μm, 8 to 1.5 μm of Y ₂ O ₃ powder was mixed and mixed so as to have the composition shown in Table 1 (Sample No. 1 to Sample No. 7).

  Each mixture was blended with a burned material (acrylic resin) having an average particle size of 20 μm, an organic binder made of cellulose, and a solvent made of water and mixed to obtain a support material. The burned-out material was added at a ratio of 15% by weight with respect to the total amount of the support material.

  As shown in FIG. 5, the obtained support material is extruded to form a support molded body 51 having a gas channel 52 inside having a major axis dimension of 35 mm, a minor axis dimension of 4.2 mm, and a flat cross section. After producing and drying, it degreased and calcined at 1200 degreeC.

  The calcined strength of the calcined support molded body 51 was measured by a three-point bending strength [MPa] (JIS R1601). Then, it baked on 1485 degreeC conditions, and the open porosity of the support body after baking was measured by the Archimedes method. The results are shown in Table 1. The calcining strength is the same as that of Sample No. Measurement was carried out using six of the support molded bodies 51 of 1 to 7 (N = 6), and the maximum value and the minimum value thereof were shown. The open porosity is measured according to Sample No. The measurement was performed using 5 supports 1 to 7 (N = 5), and the average value was shown.

As apparent from Table 1, the sample No. of the present invention containing Fe ₂ O ₃ at 0.2 mol% or less is used. 1-No. In the support body 51 of No. 5, all the minimum values of the calcining strength were larger than 2 MPa, and it was confirmed that sufficient strength was maintained. In addition, all of the open porosity values were 30% or more.

On the other hand, sample No. which does not contain Fe ₂ O ₃ . 6 shows that the minimum value of the calcining strength of the support 51 is less than 2 MPa, and it can be confirmed that sufficient strength cannot be obtained. In the subsequent manufacturing process, the support 51 may be damaged. It was. Furthermore, Sample No. containing Fe ₂ O ₃ in an amount of more than 0.2 mol%. In No. 7, the calcining strength of the support 51 was sufficient, but the open porosity was less than 30%.

(Preparation of support molded body)
A support material was obtained in the same manner as in Example 1 except that the composition shown in Table 2 (Sample No. 8 to Sample No. 13) was used instead of the composition shown in Table 1. This support material was extruded in the same manner as in Example 1, and as shown in FIG. 5, a support having a major axis dimension of 35 mm, a minor axis dimension of 4.2 mm, and a transverse cross section having a flat shape as shown in FIG. A compact 51 was produced.

(Production of fuel electrode layer tape and solid electrolyte layer tape)
As shown in FIG. 6 (a), a slurry obtained by mixing an acrylic binder and toluene with 8YSZ powder having an average particle size of 0.5 μm is applied by a doctor blade method and dried to obtain a solid electrolyte having a thickness of 40 μm. A layer tape 53b was produced.

  Next, Ni powder having an average particle size of 0.5 μm and 8YSZ powder having an average particle size of 0.5 μm were blended and mixed so that the volume ratio of Ni powder to 8YSZ powder was 48:52. A slurry obtained by mixing a burned material, an acrylic binder, and toluene into this mixture was applied by a doctor blade method and dried to prepare a fuel electrode layer tape 53a having a thickness of about 80 μm.

Next, as shown in FIG. 6B, the fuel electrode layer tape 53a and the solid electrolyte layer tape 53b are such that the portions where they do not overlap each other have a width of 3 mm. As shown in FIG. 6 (c), the layers were bonded together at a pressure of 2000 kg / cm ² . A laminated tape obtained by bonding these fuel electrode layer tape 53a and solid electrolyte layer tape 53b to the sample No. shown in Table 2 was used. 8-No. It was affixed in the shape of a horizontal stripe on each support body molded body 51 having a composition of 13. Further, one laminated tape and another laminated tape adjacent thereto were arranged with an interval of 10 mm. Then, this support body molded body 51 was dried and calcined at 1250 ° C.

(Production of interconnector molded body and cell stack connecting member molded body)
Next, a slurry for dip is prepared with lanthanum chromite (LaCrO ₃ ) and a PVA-based binder, and then, as shown in FIG. 7 (a), the portions excluding both ends of the previously prepared laminated tape are masked tape. Covered with 61. Thereafter, it was dipped with a slurry for dipping, then dried, the masking tape was removed to form the interconnector 14 and the inter-cell stack connection member 15, and then baked at 1485 ° C. for 2 hours.

(Preparation of air electrode layer compact)
Next, as shown in FIG. 8 (a), the entire surface of the inter-cell stack connecting member 15 and a part of the interconnector 14 on the opposite side of the interconnector 14 to the fuel electrode layer tape 13a are excluded. The surface was masked with a masking tape 63. Next, as shown in FIG. 8B, a slurry obtained by mixing lanthanum cobaltite (LaCoO ₃ ) having an average particle diameter of 0.7 μm and isopropyl alcohol was sprayed on the masked laminate, and an air electrode layer having a thickness of 20 μm. A molded body 53c was formed.

(Production of horizontal stripe type solid oxide fuel cell stack)
Next, the masking tape 63 of the laminated body on which the air electrode layer molded body 53c was formed was removed, and thereafter, the treatment was performed at 1100 ° C. to produce the horizontal stripe solid oxide fuel cell stack shown in FIG.

(Evaluation of cracking of cell stack tip)
Sample No. obtained above. 8-No. The reducing gas (N ₂ / H ₂ ) is introduced into the gas flow path of the support constituting each of the cell stacks 13 and the oxygen-containing gas (air) is introduced into the outer peripheral portion. The temperature was raised so that the vicinity was 800 to 850 ° C., and the temperature was maintained for 200 hours. Thereafter, the cell stack was taken out from the furnace, and the presence or absence of cracks at the tip was observed with a microscope. The results are shown in Table 2.

  As is apparent from Table 2, the sample No. having a Ni / MgO ratio in the range of 0.15 to 0.25. 8 to Sample No. In 13 cell stacks, no cracks at the tip were observed. Thereby, it turned out that the crack of a front-end | tip part can be suppressed by making Ni / MgO ratio into the range of 0.15-0.25.

  FIG. 9 is a graph showing the relationship between the open porosity of the support body from which all of the fuel battery cells have been peeled and the limit fuel utilization ratio in the fuel battery cell after the fuel battery cells are stacked on the support body and fired. . That is, the open porosity in this example means the open porosity of the support from which all the fuel cells have been peeled. A test was conducted by preparing a support having each open porosity shown in FIG. 9 by adding a predetermined amount of a burned material having an average particle diameter of 20 μm to the composition No. 11. The limit fuel utilization rate indicates that the amount of power generation rapidly decreases when the fuel utilization rate in the fuel cell falls below the value.

The critical fuel utilization was measured in a state where the fuel cells were stacked on the support and fired, that is, in a state of the cell stack before peeling the fuel cells. The cell stack was produced in the same manner as in Example 2 except that the support having each open porosity shown in FIG. 9 was produced. The critical fuel utilization rate is measured by first introducing reducing gas (N ₂ / H ₂ ) into the gas flow path of the support, and oxidizing gas (air) into the outer periphery, and 750 ° C. at the center of the cell stack (front end The temperature was raised so that the vicinity of the part was 800 to 850 ° C., and the temperature was maintained for 200 hours. Thereafter, the fuel utilization was changed by adjusting the flow rate of the reducing gas (N ₂ / H ₂ ), and at the same time, the cell voltage of the cell stack was measured and evaluated.

  As is apparent from FIG. 9, when the open porosity of the support is less than 30%, the limit fuel utilization rate is less than 65%, and power can be generated efficiently in the fuel cell (cell stack). I find it difficult. On the other hand, when the open porosity of the support is 30% or more, the limit fuel utilization rate exceeds 65%, and when the open porosity is 32% or more, the limit fuel utilization rate is 70%. The power generation can be efficiently performed in the fuel cell (cell stack). Therefore, the open porosity of the support constituting the cell stack needs to be 30% or more, preferably 32% or more.

It is a longitudinal cross-sectional view which expands and shows a part of horizontal stripe type solid oxide fuel cell stack concerning one Embodiment of this invention. It is a cross-sectional view which expands and shows a part of horizontal stripe type solid oxide fuel cell stack concerning one embodiment of the present invention. It is a longitudinal cross-sectional view which expands and shows the edge part connection structure of the horizontal stripe type solid oxide fuel cell stack concerning one Embodiment of this invention. It is a longitudinal cross-sectional view which shows the bundle comprised by arranging three horizontally striped solid oxide fuel cell stacks concerning one Embodiment of this invention. It is a longitudinal cross-sectional view which shows the support body of the horizontal stripe type solid oxide fuel cell stack concerning one Embodiment of this invention. (A)-(c) is a longitudinal cross-sectional view which shows the manufacturing process of the fuel cell of the horizontal stripe type solid oxide fuel cell stack concerning one Embodiment of this invention. (A)-(c) is a longitudinal cross-sectional view which shows the formation process of the interconnector which electrically connects between the fuel cells of the horizontal stripe type solid oxide fuel cell stack concerning one embodiment of the present invention. . (A)-(c) is a longitudinal cross-sectional view which shows the preparation process of the air electrode layer of the horizontal stripe type solid oxide fuel cell stack concerning one Embodiment of this invention. It is a graph which shows the relationship between the open porosity of a support body in an Example, and a fuel utilization factor. It is a longitudinal cross-sectional view which expands and shows a part of conventional horizontal stripe type solid oxide fuel cell stack.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Support body 12 Gas flow path 13 Fuel cell 13a Fuel electrode layer 13b Solid electrolyte layer 13c Air electrode layer 14 Interconnector 15 Inter-cell stack connection member 20 Conductive member

Claims (3)

A plurality of fuel cells, each of which is formed by laminating an inner electrode layer, a solid electrolyte layer, and an outer electrode layer in this order, are arranged side by side on the surface of an electrically insulating support provided with a gas flow path. A horizontal stripe type in which an inner electrode layer of a cell and an outer electrode layer of the other fuel cell adjacent to the one fuel cell are electrically connected, and the plurality of fuel cells are connected in series A solid oxide fuel cell stack,
The support includes Ni having a content of 11.3 to 17.62 mol% in terms of NiO with respect to the total amount of the support, and MgO having a content of 70.48 to 75.54 mol% with respect to the total amount of the support. When a Fe ₂ O ₃ of 0.20 mol% or less of the content, comprise Do Rutotomoni and Y ₂ O ₃ of from 10.285 to 13.32 mole% of the content with respect to the support amount, open A horizontally-striped solid oxide fuel cell stack having a porosity of 30% or more. The horizontal stripe solid oxide fuel cell stack according to claim 1, wherein the support has a hollow plate shape. A fuel cell comprising a plurality of horizontally-striped solid oxide fuel cell stacks according to claim 1 or 2 in a storage container.