JP5501299B2 - Fuel cell structure - Google Patents

Description

  The present invention relates to a fuel cell structure.

  Conventionally, “a flat porous support substrate having a longitudinal direction in which a gas flow path is formed by integral firing” and “at least an inner electrode, a solid substrate disposed on the main surface of the flat support substrate” There is known a structure of a fuel cell including an electrolyte and one or a plurality of power generation element portions in which outer electrodes are stacked (see, for example, Patent Document 1).

  In recent years, regarding a fuel cell structure of this type, an inlet and an outlet of a gas channel are formed at one end in the longitudinal direction of the support substrate, and the gas channel extends from the inlet to the length of the support substrate. "Outward path part" extending to the other side of the direction, "return path part" extending from the other side in the longitudinal direction of the support substrate to the outlet, and the longitudinal direction of the other side end part of the forward path part and the return path part Has been developed (that is, a configuration in which the gas flow path is formed in a U shape) (for example, Patent Documents 2 and 3). See).

  As described above, the inlet and outlet of the gas flow path are formed at one end in the longitudinal direction of the support substrate, so that the gas supply pipe that supplies gas to the inlet and the exhaust gas are recovered from the outlet. Both gas exhaust pipes can be provided at one end in the longitudinal direction of the support substrate. In other words, the above-described gas exhaust pipe can be provided while adopting a structure (so-called cantilever structure) that supports the support substrate only at one end in the longitudinal direction. Therefore, the exhaust gas exhausted from the outlet can be collected by the gas exhaust pipe, and combustion of the exhaust gas due to the reaction with air (oxygen) in the vicinity of the outlet can be suppressed. As a result, it is possible to suppress the occurrence of a local temperature rise at the end of the support substrate due to the combustion of the exhaust gas. In addition, when a temperature difference (temperature distribution) occurs in the support substrate during operation of the fuel cell or the like, the support substrate is easily deformed freely due to the cantilever structure. As a result, the occurrence of cracks and the like in the support substrate due to thermal stress can be suppressed.

JP 2008-226789 A Japanese Patent No. 2802345 Japanese Patent No. 3447837

  By the way, in the structure of the fuel cell described in Patent Documents 2 and 3, the “outward path portion” and the “return path portion” of the U-shaped gas flow path are formed at the same position in the thickness direction of the support substrate. Yes. In other words, the U-shaped gas flow path is formed in a plane parallel to the main surface of the support substrate.

  On the other hand, the present inventor forms various new actions and effects by forming the “outward path part” and the “return path part” of the U-shaped gas flow path at different positions in the thickness direction of the support substrate. It has been found that a wide variety of fuel cell structures capable of achieving the above can be provided.

  That is, the fuel cell structure according to the present invention includes a flat plate-like porous support substrate having a gas flow path formed therein by integral firing and a main surface of the flat plate-like support substrate. And one or a plurality of power generation element units that are arranged and at least an inner electrode, a solid electrolyte, and an outer electrode are stacked. This structure has a configuration in which a plurality of power generation element portions are arranged at different positions on the main surface of the support substrate (so-called “horizontal stripe type”), but the plurality of power generation element portions are the main portions of the support substrate. You may have the structure (what is called a "vertical stripe type") laminated | stacked on a certain position on the surface.

  In the fuel cell structure according to the present invention, the inlet and outlet of the gas flow path are formed at one end of the support substrate in the longitudinal direction, and the gas flow path is formed of the inlet. A forward path portion extending from the other longitudinal side of the support substrate to the outflow port, and an end portion on the other longitudinal side of the forward path portion. And an intermediate portion connecting the end portion on the other side in the longitudinal direction of the return path portion. That is, a U-shaped gas flow path is formed. This gas flow path may be a flow path for fuel gas or a flow path for gas containing oxygen.

  The fuel cell structure according to the present invention is characterized in that the return path portion and the forward path portion are formed at different positions in the thickness direction of the support substrate. According to this, as explained below, a wide variety of fuel cell structures can be provided. As a result, various new actions and effects can be achieved.

  Specifically, firstly, “the power generation element portions are respectively disposed at a plurality of positions located apart from each other along the longitudinal direction of each of the pair of parallel main surfaces of the flat plate-like support substrate. In the case where one inner electrode and the other outer electrode of the adjacent power generation element portions are electrically connected to each other, that is, “a plurality of“ horizontal stripe type ”power generation on both sides of a pair of main surfaces of the support substrate”. The case where the element portion is arranged ”will be described.

  In this first case, the forward path portion of the gas flow path extends from the inflow port to the other side in the longitudinal direction of the support substrate at the center in the thickness direction of the support substrate, and the gas flow path An intermediate portion extends from a center portion in the thickness direction of the support substrate to one side and the other side in the thickness direction, respectively, and the return path portion of the gas flow path is one side and the other side in the thickness direction. The gas flow path may be configured to extend from the other side in the longitudinal direction of the support substrate to the outlet.

  2ndly, "The said power generation element is in several places located mutually apart along the said longitudinal direction only in the 1st main surface of the 1st, 2nd main surfaces parallel to each other of the said flat support substrate. Portions are arranged, and one inner electrode and the other outer electrode of the adjacent power generation element portions are electrically connected to each other ”, that is,“ the first main surfaces of the first and second main surfaces of the support substrate ”. A description will be given of a case where “a plurality of horizontal stripe-type power generation element portions are disposed only on the surface”.

  In this second case, the forward path portion of the gas flow path extends from the inflow port to the other side in the longitudinal direction of the support substrate on the side close to the second main surface in the thickness direction of the support substrate, The intermediate portion of the gas flow path extends from a side near the second main surface in the thickness direction of the support substrate to a side close to the first main surface, and the return path portion of the gas flow path is The gas flow path may be configured to extend from the other side in the longitudinal direction of the support substrate to the outflow port on a side near the first main surface in the thickness direction.

  Alternatively, in this case, the forward path portion of the gas flow path extends from the inflow port to the other side in the longitudinal direction of the support substrate on the side close to the first main surface in the thickness direction of the support substrate, The intermediate portion of the gas flow path extends from a side near the first main surface in the thickness direction of the support substrate to a side close to the second main surface, and the return path portion of the gas flow path is the thickness The gas flow path may be configured to extend from the other side in the longitudinal direction of the support substrate to the outflow port on a side close to the second main surface in the vertical direction. As described above, in the first and second cases, the inner electrode and the outer electrode may be a fuel electrode and an air electrode, respectively, or may be an air electrode and a fuel electrode.

Third, “the power generation element portion is arranged on the first main surface of the first and second main surfaces parallel to each other of the flat support substrate, and the second main surface is connected to the outside. In the case where an electrically connected interconnector is disposed, that is, “one power generation element portion or only“ vertical stripe type ”power generation elements for only the first main surfaces of the first and second main surfaces of the support substrate. Will be described. In the third case, the inner electrode and the outer electrode are a fuel electrode and an air electrode, respectively. Here, the interconnector (fuel electrode side of the terminal electrodes) has the formula _{La 1-x A x Cr 1} -y + z B y O 3 ( provided that, A: Ca least one element, Sr, is selected from Ba , B: at least one element selected from Co, Ni, Al, x range: 0.05 to 0.2, y range: 0.02 to 0.22, z range: 0.02 It is preferable that the lanthanum chromite represented by 0.05) is included.

  In the third case, the forward path portion of the gas flow path extends from the inlet to the other side in the longitudinal direction of the support substrate on the side close to the first main surface in the thickness direction of the support substrate. The intermediate portion of the gas flow path extends from a side near the first main surface in the thickness direction of the support substrate to a side close to the second main surface, and the return path portion of the gas flow path is The gas flow path may be configured to extend from the other side in the longitudinal direction of the support substrate to the outflow port on a side close to the second main surface in the thickness direction. Hereinafter, the operation and effect of this configuration will be described.

  In this configuration, the fuel gas flowing in the forward path portion disposed in the vicinity of the first main surface is consumed by the reaction at the fuel electrode of the power generation element portion disposed on the first main surface and generates water vapor. Proceed to the middle part. That is, it is considered that the concentration of the fuel gas in the forward path portion gradually decreases as the position moves from one side to the other side in the longitudinal direction. Therefore, the fuel gas is thin when the fuel gas enters the return path via the intermediate portion. In addition, since the power generation element portion is not arranged on the second main surface side, the fuel gas flowing through the return path portion arranged in the vicinity of the second main surface consumes fuel by the reaction in the power generation element portion. Proceed to the outlet without any problems. As described above, the inner side surface of the interconnector disposed on the second main surface is exposed to a thin and uniform fuel gas.

  On the other hand, lanthanum chromite is generally used as a material for the interconnector (terminal electrode on the fuel electrode side). This is based on the fact that the inner surface of the terminal electrode on the fuel electrode side is exposed to a reducing atmosphere and the outer surface is exposed to an oxidizing atmosphere. At present, lanthanum chromite is excellent as a conductive ceramic that is stable in both oxidizing and reducing atmospheres. Lanthanum chromite has the property of expanding when exposed to a strong reducing atmosphere. Therefore, when one surface of a plate-like object made of lanthanum chromite is exposed to a strong reducing atmosphere and the other surface is exposed to an oxidizing atmosphere, the object warps due to a difference in expansion between both surfaces. In this regard, according to the above configuration, the inner surface of the interconnector is exposed to a weak reducing atmosphere. Therefore, the interconnector is difficult to warp.

  In addition, the inner surface of the interconnector is exposed to a uniform reducing atmosphere. Accordingly, the distribution of stress that may be generated due to the expansion is suppressed in the interior of the interconnector or at the interface with other materials to be joined to the interconnector, and the interconnector is destroyed or peeled off due to the stress distribution. Can be suppressed. The above-described expansion of lanthanum chromite is described in detail in, for example, Electrochemistry_68, No. 2 (2000) _p526-530.

  Further, in the third case, the forward path portion of the gas flow path is from the inlet to the other side in the longitudinal direction of the support substrate on the side close to the second main surface in the thickness direction of the support substrate. The intermediate portion of the gas flow path extends from a side near the second main surface in the thickness direction of the support substrate to a side close to the first main surface, and the return path portion of the gas flow path The gas flow path may be configured to extend from the other side in the longitudinal direction of the support substrate to the outflow port on the side near the first main surface in the thickness direction.

  In the various fuel cell structures described above, the forward path portion of the gas flow path is disposed on the side closer to the “main surface of the support substrate on which the power generation element portion is disposed” in the thickness direction of the support substrate. If not, the inner wall of the forward path portion of the gas flow path may be made of a material having a lower porosity than the porous material constituting the support substrate. The film of the “material with low porosity” can be formed by, for example, coating. Hereinafter, the operation and effect of this configuration will be described.

  The support substrate is made of a porous material. Therefore, a part of the gas flowing in the forward path portion does not reach the intermediate portion, and shortcuts to the return path portion through a large number of pores in the porous material constituting the support substrate. The ratio of the gas to be short-cut in this way is likely to increase when the porosity of the porous material is large or when the pressure of the gas flowing in from the inlet is high. When the ratio of the gas to be short-cut increases, the gas that reaches the intermediate portion decreases, and the region that can contribute to power generation in the power generation element portion is narrowed. This leads to a decrease in the power generation output of the fuel cell. Therefore, when a large proportion of the shortcut gas is a problem, it is necessary to take measures to suppress the shortcut.

  This configuration is based on such knowledge. According to this structure, the shortcut of the gas which flows through an outward path part is suppressed. Accordingly, the ratio of the gas to be short-cut decreases, and the ratio of the gas that reaches the middle portion increases. As a result, it is possible to suppress a decrease in the power generation output of the fuel cell due to the gas shortcut.

  As described above, when the inner wall of the forward path portion of the gas flow path is composed of the “material having a low porosity”, the “material having a low porosity” is a catalyst component that promotes a reforming reaction of fuel gas. May be included. A fuel gas reforming reaction (for example, a reaction for generating hydrogen molecules from city gas) is an endothermic reaction. Therefore, according to this configuration, by supplying “gas before reforming” (for example, city gas) from the inlet of the gas flow path, a reforming reaction (= endothermic reaction) occurs in the gas flowing in the forward path portion. To do.

  As a result, “reformed gas” (for example, hydrogen molecules) that can be used in the power generation element section is obtained in the forward path section. The “modified gas” is subjected to a power generation reaction in the power generation element section. This power generation reaction is an exothermic reaction resulting from the internal resistance of the power generation element portion and the thermodynamic entropy term. Due to this exothermic reaction, the temperature of the power generation element portion increases. On the other hand, an endothermic reaction accompanying the reforming reaction occurs in the forward path portion. Due to this endothermic reaction, the temperature of the forward path portion decreases. That is, a temperature difference is generated between the power generation element portion and the forward path portion. Due to the temperature difference, a part of the heat of the power generation element portion moves to the forward path portion. For this reason, the structure which is easy to maintain a thermal balance is obtained. That is, the steady temperature of the entire fuel cell structure in operation can be maintained within an appropriate range.

  Further, the balance between the heat generation and the heat absorption described above is arbitrarily adjusted by changing the coating amount (film thickness, etc.) of the catalyst component that promotes the reforming reaction continuously or intermittently along the longitudinal direction in the forward path portion. It is possible. For example, by applying a large amount of a catalyst component that promotes the reforming reaction in the vicinity of the entrance (inlet) of the forward path, the temperature in the vicinity of the entrance (inlet) of the forward path, that is, the holding portion of the support substrate can be lowered. it can. As a result, it is possible to reduce thermal stress due to a difference in thermal expansion that acts on the joint portion between the support substrate and the ceramic material, glass material, metal material, or the like used for holding the support substrate.

1 is a perspective view showing a structure of a fuel cell according to the present invention. It is sectional drawing corresponding to the 2-2 line of the structure of the fuel cell shown in FIG. It is sectional drawing corresponding to the 3A-3A line | wire, 3B-3B line | wire, and 3C-3C line | wire of the structure of the fuel cell shown in FIG. It is a figure for demonstrating the operating state of the structure of the fuel cell shown in FIG. It is a figure for demonstrating the flow of the electric current in the operating state of the structure of the fuel cell shown in FIG. It is a perspective view which shows the support substrate shown in FIG. It is sectional drawing corresponding to the 7A-7A line | wire, 7B-7B line | wire, and 7C-7C line | wire of the support substrate shown in FIG. FIG. 3 is a cross-sectional view corresponding to FIG. 2 in a first stage in the manufacturing process of the fuel cell structure shown in FIG. 1. FIG. 3 is a cross-sectional view corresponding to FIG. 2 in a second stage in the manufacturing process of the fuel cell structure shown in FIG. 1. FIG. 3 is a cross-sectional view corresponding to FIG. 2 in a third stage in the manufacturing process of the fuel cell structure shown in FIG. 1. FIG. 4 is a cross-sectional view corresponding to FIG. 2 in a fourth stage in the manufacturing process of the fuel cell structure shown in FIG. 1. FIG. 6 is a cross-sectional view corresponding to FIG. 2 in a fifth stage in the manufacturing process of the fuel cell structure shown in FIG. 1. FIG. 7 is a cross-sectional view corresponding to FIG. 2 in a sixth stage in the manufacturing process of the fuel cell structure shown in FIG. 1. FIG. 8 is a cross-sectional view corresponding to FIG. 2 in a seventh stage in the manufacturing process of the fuel cell structure shown in FIG. 1. It is sectional drawing corresponding to FIG. 3 of the 1st modification of the structure of the fuel cell which concerns on this invention. It is sectional drawing corresponding to FIG. 3 of the 2nd modification of the structure of the fuel cell concerning this invention. It is sectional drawing corresponding to FIG. 3 of the 3rd modification of the structure of the fuel cell concerning this invention. It is sectional drawing corresponding to FIG. 3 of the 4th modification of the structure of the fuel cell concerning this invention. FIG. 10 is a cross-sectional view corresponding to FIG. 3 of a fifth modification of the fuel cell structure according to the present invention. FIG. 10 is a cross-sectional view corresponding to FIG. 3 of a sixth modification of the fuel cell structure according to the present invention. FIG. 10 is a cross-sectional view corresponding to FIG. 3 of a seventh modification of the fuel cell structure according to the present invention. It is the figure which showed an example of the shape for attaching the manifold in "the edge part of the one side of the longitudinal direction of a support substrate" in which the inflow port and the outflow port were formed. It is the figure which showed an example of the shape of the manifold attached to the edge part of the one side of the longitudinal direction of the support substrate shown in FIG. FIG. 24 is a main cross-sectional view showing a state in which the manifold shown in FIG. 23 is attached to one end in the longitudinal direction of the support substrate shown in FIG. 22. It is the figure which showed the other example of the shape for attaching the manifold in "the edge part of the one side of the longitudinal direction of a support substrate" in which the inflow port and the outflow port were formed. It is the figure which showed an example of the shape of the manifold attached to the edge part of the one side of the longitudinal direction of the support substrate shown in FIG. FIG. 27 is a main cross-sectional view showing a state in which the manifold shown in FIG. 26 is attached to one end portion in the longitudinal direction of the support substrate shown in FIG. 25. It is sectional drawing corresponding to FIG. 2 of the 8th modification of the structure of the fuel cell which concerns on this invention. It is the top view which showed the state of the fuel electrode and interconnector which were embed | buried under the recessed part of the support substrate shown in FIG. It is a perspective view corresponding to FIG. 6 of the support substrate shown in FIG.

(Constitution)
FIG. 1 shows a structure of a solid oxide fuel cell (SOFC) according to an embodiment of the present invention. This SOFC structure has a plurality (in this example, electrically connected in series to the upper and lower surfaces (main surfaces (planar surfaces) on both sides parallel to each other) of the flat support substrate 10 having a longitudinal direction. The four power generation element portions A having the same shape are arranged at predetermined intervals in the longitudinal direction and have a so-called “horizontal stripe type” configuration. The “main surface” of the support substrate 10 refers to a plane having a larger area than other planes among a plurality of planes constituting the outer surface of the support substrate.

  The shape of the entire SOFC structure viewed from above is, for example, a rectangle having a side length of 5 to 50 cm in the longitudinal direction and a length of 1 to 10 cm in the width direction perpendicular to the longitudinal direction. The total thickness of the SOFC structure is 1 to 10 mm. The entire SOFC structure has a vertically symmetrical shape with respect to a plane passing through the center in the thickness direction and parallel to the main surface of the support substrate 10. Hereinafter, in addition to FIG. 1, FIG. 2, which is a partial cross-sectional view corresponding to the line 2-2 shown in FIG. 1, and the 3A-3A line, 3B-3B line shown in FIG. Details of the SOFC structure will be described with reference to FIG. 3 which is a cross-sectional view corresponding to the line 3C-3C.

  FIG. 2 shows a configuration (part of) each of a typical pair of adjacent power generation element portions A and A, and a configuration between the power generation element portions A and A. The configuration between the other power generation element portions A and A in other sets is the same as the configuration shown in FIG. FIG. 3 shows that the support substrate 10 is parallel to the thickness direction at positions (three locations) including the “fuel gas flow path 11 passing through a plane parallel to the thickness direction of the support substrate” in the width direction of the support substrate 10. A cross section obtained by cutting on a flat surface is shown.

  The support substrate 10 is a flat plate-like fired body made of a porous material having no electronic conductivity. The support substrate 10 includes the fuel gas passage 11 and is integrally fired as a whole. As shown in FIG. 3, inside the support substrate 10, “in the plane parallel to the thickness direction of the support substrate 10” is passed at a plurality of locations (three locations in this example) in the width direction of the support substrate 10. Fuel gas passages 11 "are respectively formed. Both the inflow port 11in and the outflow port 11out of each fuel gas channel 11 are formed at one end (end surface) of the support substrate 10 in the longitudinal direction.

  Each fuel gas flow path 11 includes an outward path portion 11a extending from the inflow port 11in to the other side in the longitudinal direction, and a pair of return path portions 11b and 11b extending from the other longitudinal side of the support substrate 10 to the outflow port 11out, It is composed of a pair of intermediate portions 11c and 11c that connect the end portion on the other side in the longitudinal direction of the forward path portion 11a and the respective end portions on the other side in the longitudinal direction of the pair of return path portions 11b and 11b.

  More specifically, the forward path portion 11 a linearly extends from the inflow port 11 in to the other side in the longitudinal direction along the longitudinal direction of the support substrate 10 at the central portion in the thickness direction of the support substrate 10. The pair of intermediate portions 11c and 11c linearly extend from the center portion in the thickness direction of the support substrate 10 to one side and the other side in the thickness direction. The pair of return path portions 11b and 11b are linearly formed from the other side in the longitudinal direction of the support substrate 10 to the outflow port 11out along the longitudinal direction of the support substrate 10 on one side and the other side in the thickness direction of the support substrate 10. Each extends. That is, the return path portion 11 a and the forward path portion 11 b are formed at different positions in the thickness direction of the support substrate 10.

  The fuel gas in each fuel gas channel 11 travels through the central portion in the thickness direction from the inflow port 11in toward the other side in the longitudinal direction in the forward path portion 11a, and then thick in the pair of intermediate portions 11c and 11c. Proceed to one side and the other side in the vertical direction, and then proceed from the other side in the longitudinal direction toward the outflow port 11out through the pair of return passage portions 11b and 11b.

The support substrate 10 can be made of, for example, CSZ (calcia stabilized zirconia). Alternatively, it may be composed of NiO (nickel oxide) and YSZ (8YSZ) (yttria stabilized zirconia), NiO (nickel oxide) and Y ₂ O ₃ (yttria), or MgO. (Magnesium oxide) and MgAl ₂ O ₄ (magnesia alumina spinel) may be used. The thickness of the support substrate 10 is 1 to 10 mm. Hereinafter, only the configuration on the upper surface side of the support substrate 10 will be described in consideration of the fact that the shape of the structure is vertically symmetrical. The same applies to the configuration of the lower surface side of the support substrate 10.

  As shown in FIGS. 1 and 2, a plurality (four in this example) of rectangular parallelepiped fuel electrodes 20 on the upper surface (upper main surface) of the support substrate 10 have a predetermined interval in the longitudinal direction. Are provided so as to protrude from the upper surface (plane). The fuel electrode 20 is a fired body made of a porous material having electron conductivity. The fuel electrode 20 includes a fuel electrode active part 22 that contacts a solid electrolyte membrane 40 described later, and a fuel electrode current collector 21 that is the remaining part other than the fuel electrode active part 22.

The fuel electrode active part 22 may be composed of, for example, NiO (nickel oxide) and YSZ (8YSZ) (yttria stabilized zirconia). Or you may comprise from NiO (nickel oxide) and GDC (gadolinium dope ceria). The fuel electrode current collector 21 can be composed of, for example, NiO (nickel oxide) and YSZ (8YSZ) (yttria stabilized zirconia). Alternatively, it may be composed of NiO (nickel oxide) and Y ₂ O ₃ (yttria), or may be composed of NiO (nickel oxide) and CSZ (calcia stabilized zirconia). The thickness of the anode active portion 22 is 5 to 30 μm, and the thickness of the anode current collecting portion 21 (that is, the depth of the recess 12) is 50 to 500 μm.

A thin plate-like interconnector 30 is formed at a predetermined position on the upper surface of each fuel electrode 20 (more specifically, each fuel electrode current collector 21). The interconnector 30 is a fired body made of a dense material having electronic conductivity. The shape of the interconnector 30 as viewed from above is a rectangle extending in the width direction over the range where the fuel electrode 20 exists. The interconnector 30 can be composed of, for example, LaCrO ₃ (lanthanum chromite). Alternatively, it may be composed of (Sr, La) TiO ₃ (strontium titanate). The thickness of the interconnector 30 is 10 to 100 μm.

  The outer peripheral surface extending in the longitudinal direction of the support substrate 10 in a state in which the plurality of fuel electrodes 20 protrudes, excluding the portion where the plurality of interconnectors 30 are formed, and the other end surface in the longitudinal direction of the support substrate 10 are The solid electrolyte membrane 40 is covered. The solid electrolyte membrane 40 is a fired body made of a dense material having ionic conductivity and not electron conductivity. The solid electrolyte membrane 40 can be made of, for example, YSZ (8YSZ) (yttria stabilized zirconia). Or you may comprise from LSGM (lantern gallate). The thickness of the solid electrolyte membrane 40 is 3 to 50 μm.

  That is, the entire outer peripheral surface extending in the longitudinal direction of the support substrate 10 with the plurality of fuel electrodes 20 projecting, and the other end surface in the longitudinal direction of the support substrate 10 are formed from the interconnector 30 and the solid electrolyte membrane 40. It is covered with a dense layer. This dense layer exhibits a gas sealing function that prevents mixing of the fuel gas flowing in the space inside the dense layer and the air flowing in the space outside the dense layer.

  An air electrode 60 is formed on the upper surface of a portion in contact with each fuel electrode active part 22 in the solid electrolyte membrane 40 via a reaction preventing film 50. The reaction preventing film 50 is a fired body made of a dense material, and the air electrode 60 is a fired body made of a porous material having electron conductivity. The shape of the reaction preventing film 50 and the air electrode 60 viewed from above is substantially the same rectangle as the fuel electrode active part 22.

The reaction preventing film 50 can be made of, for example, GDC = (Ce, Gd) O ₂ (gadolinium-doped ceria). The thickness of the reaction preventing film 50 is 3 to 50 μm. The air electrode 60 can be made of, for example, LSCF = (La, Sr) (Co, Fe) O ₃ (lanthanum strontium cobalt ferrite). Alternatively, from LSF = (La, Sr) FeO ₃ (lanthanum strontium ferrite), LNF = La (Ni, Fe) O ₃ (lanthanum nickel ferrite), LSC = (La, Sr) CoO ₃ (lanthanum strontium cobaltite), etc. It may be configured. Further, the air electrode 60 may be configured by two layers of a first layer (inner layer) made of LSCF and a second layer (outer layer) made of LSC. The thickness of the air electrode 60 is 10 to 100 μm.

  The reaction preventing film 50 is interposed because the YSZ in the solid electrolyte film 40 and the Sr in the air electrode 60 react with each other in the SOFC during the production or operation of the SOFC, and the solid electrolyte film 40 and the air electrode. This is to suppress the occurrence of a phenomenon in which a reaction layer having a large electric resistance is formed at the interface with the substrate 60.

  Here, the laminated body formed by laminating the fuel electrode 20, the solid electrolyte membrane 40, the reaction preventing membrane 50, and the air electrode 60 corresponds to the “power generation element portion A” (see FIG. 2). In other words, a plurality (four in this example) of power generating element portions A are arranged on the upper surface of the support substrate 10 at a predetermined interval in the longitudinal direction.

  For each pair of adjacent power generation element portions A and A, the air electrode 60 of one power generation element portion A (on the left side in FIG. 2) and the interconnector of the other power generation element portion A (on the right side in FIG. 2). The air electrode current collecting film 70 is formed on the upper surfaces of the air electrode 60, the solid electrolyte film 40, and the interconnector 30. The air electrode current collector film 70 is a fired body made of a porous material having electron conductivity. The shape of the air electrode current collector film 70 as viewed from above is a rectangle.

The air electrode current collector film 70 can be made of, for example, LSCF = (La, Sr) (Co, Fe) O ₃ (lanthanum strontium cobalt ferrite). Alternatively, LSC = (La, Sr) CoO ₃ (lanthanum strontium cobaltite) may be used. Or you may comprise from Ag (silver) and Ag-Pd (silver palladium alloy). The thickness of the air electrode current collector film 70 is 50 to 500 μm.

  By forming each air electrode current collecting film 70 in this way, for each pair of adjacent power generation element portions A and A, the air electrode 60 of one power generation element portion A (on the left side in FIG. 2), The other fuel electrode 20 (particularly, the fuel electrode current collector 21) of the power generating element part A (on the right side in FIG. 2) passes through the “air electrode current collector film 70 and interconnector 30” having electronic conductivity. Are electrically connected. As a result, a plurality (four in this example) of power generation element portions A arranged on the upper surface of the support substrate 10 are electrically connected in series. Here, the “air electrode current collector film 70 and the interconnector 30” having electronic conductivity correspond to “electrical connection portions”.

When the “horizontal stripe type” SOFC structure described above is operated, one end in the longitudinal direction of the support substrate 10 (that is, the end where the inflow port 11in and the outflow port 11out are exposed). Further, a gas supply pipe (not shown) for supplying fuel gas to the inflow port 11in and a gas exhaust pipe (not shown) for recovering the fuel gas exhausted from the outflow port 11out are connected. . The gas supply pipe and the gas exhaust pipe may be integrated or separate. Then, as shown in FIG. 4, fuel gas (hydrogen gas or the like) flows through the fuel gas flow path 11 of the support substrate 10, and the upper and lower surfaces (particularly, each air electrode current collector film 70) are placed on An electromotive force is generated by an oxygen partial pressure difference generated between both side surfaces of the solid electrolyte membrane 40 by exposing to oxygen-containing gas (air or the like) (or flowing a gas containing oxygen along the upper and lower surfaces of the support substrate 10). Occur. Furthermore, when this structure is connected to an external load, chemical reactions shown in the following formulas (1) and (2) occur, and current flows (power generation state).
(1/2) · O ₂ + 2e ⁻ → O ²⁻ (where: air electrode 60) (1)
H ₂ + O ²⁻ → H ₂ O + 2e ⁻
(At: Fuel electrode 20) (2)

  In the power generation state, as shown in FIG. 5, a current flows as indicated by an arrow in each pair of adjacent power generation element portions A and A. As a result, as shown in FIG. 4, the SOFC structure as a whole (specifically, the interconnector 30 of the power generating element part A on the frontmost side in FIG. 4 and the air electrode of the power generating element part A on the innermost side in FIG. The power is extracted (via 60).

(Production method)
Next, an example of a manufacturing method of the “horizontal stripe type” SOFC structure shown in FIG. 1 will be briefly described with reference to FIGS. 6 to 14, “g” at the end of the reference numeral of each member represents that the member is “before firing”.

  First, FIG. 6 which is an overall perspective view, and a molded body of a support substrate having the shape shown in FIG. 7 which is a cross-sectional view corresponding to the lines 7A-7A, 7B-7B and 7C-7C shown in FIG. 10 g is produced. The molded body 10g of the support substrate is manufactured by using a method such as extrusion molding or cutting using a slurry obtained by adding a binder or the like to the material of the support substrate 10 (for example, CSZ). obtain. Hereinafter, the description will be continued with reference to FIGS. 8 to 14 showing partial cross sections corresponding to line 8-8 shown in FIG.

  As shown in FIG. 8, when the support substrate molded body 10g is manufactured, next, as shown in FIG. 9, the fuel electrode is formed in each of a plurality of predetermined locations on the upper and lower surfaces of the support substrate molded body 10g. A molded body (21 g + 22 g) is laminated and formed. Each fuel electrode molded body (21 g + 22 g) is laminated and formed using a slurry obtained by adding a binder to the powder of the material of the fuel electrode 20 (for example, Ni and YSZ), using a printing method or the like. Is done.

Next, as shown in FIG. 10, a molded film 30g of the interconnector is formed at a predetermined location on the outer surface of the molded body 21g of each fuel electrode. The molded film 30g of each interconnector is formed by using a printing method or the like using a slurry obtained by adding a binder or the like to the powder of the material of the interconnector 30 (for example, LaCrO ₃ ).

  Next, as shown in FIG. 11, a plurality of interconnector molded bodies 30g on the outer peripheral surface extending in the longitudinal direction of the molded body 10g of the support substrate in which a plurality of molded fuel electrode bodies (21g + 22g) are laminated and formed. A solid electrolyte membrane molded film 40g is formed on the entire surface excluding the portion where the is formed, and on the other end face of the support substrate molded body 10g. The molded membrane 40g of the solid electrolyte membrane is formed using, for example, a printing method, a dipping method, etc., using a slurry obtained by adding a binder or the like to the powder of the material of the solid electrolyte membrane 40 (for example, YSZ). The

  Next, as shown in FIG. 12, a reaction prevention film molding film 50g is formed on the outer surface of the solid electrolyte membrane molding body 40g in contact with the fuel electrode molding body 22g. The molded film 50g of each reaction preventing film is formed using a slurry obtained by adding a binder or the like to the powder of the material (for example, GDC) of the reaction preventing film 50, using a printing method or the like.

  Then, 10 g of the support substrate molded body in which various molded films are thus formed is fired in air at 1500 ° C. for 3 hours. As a result, a structure in which the air electrode 60 and the air electrode current collector film 70 are not formed in the SOFC structure shown in FIG. 1 is obtained.

  Next, as shown in FIG. 13, an air electrode forming film 60 g is formed on the outer surface of each reaction preventing film 50. The molded film 60g of each air electrode is formed using a slurry obtained by adding a binder or the like to the powder of the material of the air electrode 60 (for example, LSCF), using a printing method or the like.

  Next, as shown in FIG. 14, for each pair of adjacent power generation element portions, air is formed so as to straddle the air electrode molding film 60 g of one power generation element portion and the interconnector 30 of the other power generation element portion. On the outer surface of the electrode forming film 60 g, the solid electrolyte film 40, and the interconnector 30, the air electrode current collecting film forming film 70 g is formed. The forming film 70g of each air electrode current collector film is obtained by using a slurry obtained by adding a binder or the like to the powder of the material of the air electrode current collector film 70 (for example, LSCF), using a printing method or the like. It is formed.

  Then, the support substrate 10 in which the molded films 60g and 70g are thus formed is baked in air at 1050 ° C. for 3 hours. As a result, the SOFC structure shown in FIG. 1 is obtained. The example of the method for manufacturing the SOFC structure shown in FIG. 1 has been described above.

(Action / Effect)
As described above, in the “horizontal stripe type” SOFC structure according to the embodiment of the present invention, a plurality (three in this example) of fuel gas flow paths 11 are formed in the support substrate 10. Yes. Both the inflow port 11in and the outflow port 11out of each fuel gas channel 11 are formed at one end (end surface) of the support substrate 10 in the longitudinal direction. Each fuel gas flow path 11 includes an outward path portion 11a, a pair of return path portions 11b and 11b, and a pair of intermediate portions 11c and 11c.

  The forward path portion 11a linearly extends from the inflow port 11in to the other side in the longitudinal direction along the longitudinal direction of the support substrate 10 at the central portion in the thickness direction of the support substrate 10, and the pair of return path portions 11b and 11b are The one side and the other side in the thickness direction of the support substrate 10 linearly extend from the other side in the longitudinal direction of the support substrate 10 to the outlet 11out along the longitudinal direction of the support substrate 10, respectively, and a pair of intermediate portions 11c, 11c is the center in the thickness direction of the support substrate 10 to connect the end portion on the other side in the longitudinal direction of the forward path portion 11a and the respective end portion on the other side in the longitudinal direction of the pair of return path portions 11b and 11b. It extends from the portion to one side and the other side in the thickness direction. That is, the return path portion 11 a and the forward path portion 11 b are formed at different positions in the thickness direction of the support substrate 10.

  In addition, this invention is not limited to the said embodiment, A various modification can be employ | adopted within the scope of the present invention. For example, in the above embodiment, the entire inside of the support substrate 10 is made of a porous material. However, as shown in FIG. 15, the inner wall of the forward path portion 11 a of the fuel gas flow channel 11 defines the support substrate 10. You may be covered with the film | membrane 12 whose porosity is smaller than the porous material to comprise. The film 12 can be formed by, for example, coating. By providing this film 12, the following actions and effects can be exhibited.

  Since the support substrate 10 is made of a porous material, a part of the gas flowing in the forward path portion 11a does not reach the intermediate portions 11c and 11c, and passes through a large number of pores in the porous material to return the path portion. Shortcut to 11b and 11b. When the ratio of the gas to be short-cut increases, the gas that reaches the intermediate portions 11c and 11c decreases, and the region that can contribute to power generation in the power generation element portion A becomes narrower. This leads to a decrease in the power generation output of the fuel cell. Therefore, when a large proportion of the shortcut gas is a problem, it is necessary to take measures to suppress the shortcut.

  The configuration shown in FIG. 15 addresses this problem. According to this structure, the shortcut of the gas which flows through the outward path part 11a is suppressed. Therefore, the ratio of the gas to be short-cut decreases, and the ratio of the gas that reaches the intermediate portions 11c and 11c increases. As a result, it is possible to suppress a decrease in the power generation output of the fuel cell due to the gas shortcut.

  Here, the membrane 12 shown in FIG. 15 may contain a catalyst component that promotes the reforming reaction of the fuel gas. A fuel gas reforming reaction (for example, a reaction for generating hydrogen molecules from city gas) is an endothermic reaction. Therefore, according to this configuration, by supplying “the gas before reforming” (for example, city gas) from the inlet 11 in of the fuel gas channel 11, the reforming reaction (= endothermic reaction) is performed on the gas flowing in the forward path portion 11 a. Reaction) occurs.

  As a result, “reformed gas” (for example, hydrogen molecules) that can be used in the power generation element portion A is obtained in the forward path portion 11a. Here, the “reformed gas” is subjected to a power generation reaction in the power generation element portion A. Since this power generation reaction is an exothermic reaction, the temperature of the power generation element portion A rises due to this exothermic reaction. On the other hand, since an endothermic reaction accompanying the reforming reaction occurs in the forward path portion 11a, the temperature of the forward path portion 11a decreases due to this endothermic reaction. That is, a temperature difference occurs between the power generation element part A and the forward path part 11a. Due to the temperature difference, a part of the heat of the power generation element part A moves to the forward path part 11a. For this reason, the structure which is easy to maintain a thermal balance is obtained. That is, the steady temperature of the entire fuel cell structure in operation can be maintained within an appropriate range.

  In addition, the balance between the heat generation and the heat absorption described above is arbitrarily adjusted by continuously or intermittently changing the coating amount (film thickness, etc.) of the catalyst component that promotes the reforming reaction along the longitudinal direction in the forward path portion 11a. it can. For example, by applying a large amount of a catalyst component that promotes a reforming reaction in the vicinity of the inlet (inlet 11 in) of the forward path 11 a, the vicinity of the inlet (inlet 11 in) of the forward path 11 a, that is, the holding portion of the support substrate 10. The temperature can be lowered. As a result, thermal stress caused by a difference in thermal expansion acting on a joint portion between the support substrate 10 and a manifold made of a ceramic material, glass material, metal material, or the like used for holding the support substrate 10 is reduced. be able to.

  In the above-described embodiment, a plurality of “horizontal stripe type” power generation element portions A are provided on the upper and lower surfaces of the flat support substrate 10, but “horizontal stripe type” is provided only on one side of the support substrate 10. A plurality of power generating element portions A may be provided. Hereinafter, of the pair of main surfaces of the support substrate, the main surface on which the power generation element portion is provided is referred to as an “element formation main surface”, and the main surface on which the power generation element portion is not provided is referred to as an “element non-formation main surface”. Call it. The entire surface of the “element non-formation main surface” is covered with the solid electrolyte film 40.

  When a plurality of “horizontal stripe-type” power generation element portions A are provided on only one side surface of the support substrate 10 as described above, as shown in FIG. The intermediate portion 11c of the fuel gas channel 11 extends from the inlet 11in to the other side in the longitudinal direction of the support substrate 10 on the side closer to the “element non-formation main surface” than the center in the thickness direction. Extending from the side near the “element non-formation main surface” in the thickness direction to the side near the “element formation main surface”, and the return path portion 11b of the fuel gas flow path 11 is more “element formation” than the center in the thickness direction. The fuel gas channel 11 can be configured to extend from the other side in the longitudinal direction of the support substrate 10 to the outflow port 11out on the side close to the “main surface”.

  In the case of the configuration shown in FIG. 16, as shown in FIG. 17, the inner wall of the forward path portion 11 a of the fuel gas channel 11 may be covered with the film 12. According to this, the “suppressing effect of the shortcut of the gas in the forward path portion 11a” described above can be exhibited, and the decrease in the power generation output of the fuel cell due to the shortcut of the gas can be suppressed. When the membrane 12 contains a catalyst component that promotes the reforming reaction of the fuel gas, the balance between the heat generation and the heat absorption described above is arbitrarily adjusted, so that the entire structure of the fuel cell in operation The temperature can be maintained in an appropriate range.

  Further, when a plurality of “horizontal stripe-type” power generation element portions A are provided only on one side surface of the support substrate 10, the forward path portion 11 a of the fuel gas flow channel 11 is formed on the support substrate 10 as shown in FIG. 18. It extends from the inflow port 11 in to the other side in the longitudinal direction of the support substrate 10 on the side closer to the “element formation main surface” than the center in the thickness direction. It extends from the side close to the “element formation main surface” in the vertical direction to the side close to the “element non-formation main surface”, and the return path portion 11b of the fuel gas channel 11 is more “element non-formation main than the center in the thickness direction”. The fuel gas flow path 11 may be configured to extend from the other side in the longitudinal direction of the support substrate 10 to the outflow port 11out on the side close to the “surface”.

  As described above, in the above-described embodiment (see FIG. 3) and the configuration illustrated in FIGS. 15 to 18 described above, a plurality of “horizontal stripe-type” power generation element portions A are provided on both side surfaces or one side surface of the support substrate 10. However, as shown in FIG. 19, one power generation element portion A is provided on one main surface (“element formation main surface”) of the support substrate 10 and the other main surface (“element non-formation main surface”). ) May be provided with a thin plate-like interconnector 80 (terminal electrode on the fuel electrode side) made of a dense material. In the configuration shown in FIG. 19, a plurality of power generation element portions A may be stacked in the thickness direction. In this case, a plurality of “vertical stripe type” power generation element portions are formed.

  In the configuration shown in FIG. 19, the support substrate 10 also serves as the fuel electrode current collector 21 described above. Between the “element forming main surface” of the support substrate 10 and the solid electrolyte membrane 40, the fuel electrode active part 22 is interposed. An air electrode 60 is stacked on the solid electrolyte film 40 on the “element formation main surface”. Here, the laminated body formed by laminating the fuel electrode active part 22, the solid electrolyte membrane 40, and the air electrode 60 corresponds to the “power generation element part A”. The entire “element non-formation main surface” of the support substrate 10 is covered with an interconnector 80 made of a dense material.

Interconnector 80 has the formula _{La 1-x A x Cr 1} -y + z B y O 3 ( provided that, A: Ca, at least one element Sr, is selected from Ba, B: Co, Ni, selected from Al At least one element, x range: 0.05 to 0.2, y range: 0.02 to 0.22, z range: 0.02 to 0.05) Consists of. This is based on the fact that the inner surface of the terminal electrode on the fuel electrode side is exposed to a reducing atmosphere and the outer surface is exposed to an oxidizing atmosphere. At present, lanthanum chromite is excellent as a conductive ceramic that is stable in both oxidizing and reducing atmospheres.

  In the configuration shown in FIG. 19, the forward path portion 11 a of the fuel gas channel 11 is closer to the “element formation main surface” than the center in the thickness direction of the support substrate 10 in the longitudinal direction of the support substrate 10 from the inflow port 11 in. The intermediate portion 11c of the fuel gas passage 11 extends from the side close to the “element formation main surface” in the thickness direction of the support substrate 10 to the side close to the “element non-formation main surface”. The flow direction of the fuel gas is such that the return path portion 11b of the gas flow path 11 extends from the other side in the longitudinal direction of the support substrate 10 to the outlet 11out on the side closer to the “element non-formation main surface” than the center in the thickness direction. A path 11 is configured. With this configuration, the following actions and effects are exhibited.

  In the configuration shown in FIG. 19, the forward path portion 11 a is formed in the vicinity of the “element formation main surface”. Accordingly, the fuel gas flowing in the forward path portion 11a proceeds to the intermediate portion 11c while consuming fuel by the reaction in the fuel electrode active portion 22 of the power generating element portion A disposed on the “element formation main surface”. That is, the concentration of the fuel gas in the forward path portion 11a gradually decreases as the position moves from one side to the other side in the longitudinal direction. Therefore, when the fuel gas enters the return path portion 11b via the intermediate portion 11c, the fuel gas is thin.

  In addition, the return path portion 11 b is formed in the vicinity of the “element non-formation main surface”. Therefore, the fuel gas flowing through the return passage portion 11b proceeds to the outlet 11out without being consumed by the reaction in the power generation element portion. From the above, the inner side surface of the interconnector 80 arranged on the “element non-formation main surface” is exposed to a thin and uniform fuel gas.

  On the other hand, as described above, lanthanum chromite is adopted as the material of the interconnector 80. Lanthanum chromite has the property of expanding when exposed to a strong reducing atmosphere. Therefore, when one surface of a plate-like object made of lanthanum chromite is exposed to a strong reducing atmosphere and the other surface is exposed to an oxidizing atmosphere, the object warps due to a difference in expansion between both surfaces. In this regard, according to the configuration shown in FIG. 19, the inner surface of the interconnector 80 is exposed to a weak reducing atmosphere. Therefore, the interconnector 80 is difficult to warp.

  In addition, the inner surface of the interconnector 80 is exposed to a uniform reducing atmosphere. Therefore, the distribution of stress that can be generated due to the expansion can be suppressed in the interior of the interconnector 80, the interface with the support substrate 10 joined to the interconnector 80, or the like. Therefore, breakage and peeling of the interconnector 80 due to the stress distribution can be suppressed.

  Further, as shown in FIG. 19 described above, only one power generation element portion A (or a plurality of “vertical stripe type” power generation element portions A) is provided only on one side surface (“element formation main surface”) of the support substrate 10. When the interconnector 80 is provided on the other surface (“element non-formation main surface”) of the support substrate 10, as shown in FIG. It extends from the inflow port 11in to the other side in the longitudinal direction of the support substrate 10 on the side closer to the “element non-formation main surface” than the center in the thickness direction. It extends from the side close to the “element non-formation main surface” in the thickness direction to the side close to the “element formation main surface”, and the return path portion 11b of the fuel gas channel 11 is more “element formation main” than the center in the thickness direction. Outflow port 1 from the other side in the longitudinal direction of the support substrate 10 on the side close to the “surface” As extend into out, the fuel gas channel 11 may be configured.

  In the case of the configuration shown in FIG. 20, as shown in FIG. 21, the inner wall of the forward path portion 11 a of the fuel gas flow channel 11 may be covered with the film 12. According to this, the “suppressing effect of the shortcut of the gas in the forward path portion 11a” described above can be exhibited, and the decrease in the power generation output of the fuel cell due to the shortcut of the gas can be suppressed. When the membrane 12 contains a catalyst component that promotes the reforming reaction of the fuel gas, the balance between the heat generation and the heat absorption described above is arbitrarily adjusted, so that the entire structure of the fuel cell in operation The temperature can be maintained in an appropriate range.

  Further, in the above embodiment, the fuel electrode 20 is composed of two layers of the fuel electrode current collector 21 and the fuel electrode active portion 22, but the fuel electrode 20 is a single layer corresponding to the fuel electrode active portion 22. It may be configured. In addition, in the above embodiment, the “inner electrode” and the “outer electrode” are the fuel electrode and the air electrode, respectively, but they may be reversed.

  Hereinafter, the shape of one end in the longitudinal direction of the support substrate 10 (that is, the end where the inflow port 11in and the outflow port 11out are exposed) will be additionally described. In the above embodiment, as shown in FIGS. 1, 3, etc., the inflow port 11 in and the pair of outflow ports 11 out are arranged in the thickness direction of the support substrate 10 on the end surface constituted by one plane (no step). Are arranged along. In this configuration, in order to reduce the total thickness of the support substrate 10, it is necessary to arrange the adjacent inlet 11in and outlet 11out adjacent to each other on one plane. When the adjacent inlet 11in and outlet 11out are arranged close to each other on one plane, a gas seal for preventing mixing of the gas flowing in from the inlet 11in and the exhaust gas flowing out of the outlet 11out is provided. Processing for applying becomes difficult.

  In order to cope with such a problem, it is preferable to attach a manifold 90 shown in FIG. 23 to the end portion on one side in the longitudinal direction of the support substrate 10 having the end shape shown in FIG. The manifold 90 has a function of a gas supply pipe for supplying fuel gas to the inflow port 11in and a function of a gas exhaust pipe for recovering fuel gas exhausted from the outflow port 11out. 24 shows the 3A-3A line, 3B-3B line, and 3C-3C in FIG. 1 with the manifold 90 shown in FIG. 23 attached to one end in the longitudinal direction of the support substrate 10 shown in FIG. It is a fragmentary sectional view corresponding to a line.

  On the end surface on one side in the longitudinal direction of the support substrate 10 shown in FIG. 22, a long groove 13 extending in the width direction and penetrating at both ends in the center portion in the thickness direction within a range not interfering with the pair of upper and lower outlets 11out, 11out. Is formed. The cross section of the long groove 13 has a rectangular shape. An inflow port 11 in is formed on the bottom surface (plane) of the long groove 13. That is, the inflow port 11in is formed on a plane located on the inner side in the longitudinal direction from the plane on which the pair of upper and lower outflow ports 11out and 11out are formed.

  A mounting surface 91 of the manifold 90 shown in FIG. 23 has a recess 92 for inserting the entire end portion of the support substrate 10 and a gas supply path 93 for supplying fuel gas introduced from the outside to the inflow port 11in. And are formed. The recess 92 and the gas supply path 93 communicate with each other via a communication path 94 formed at one part of the side surface of the recess 92.

  Further, the manifold 90 is formed with a gas exhaust passage 95 for recovering the exhaust gas discharged from the outlet 11out. The recess 92 and the gas exhaust passage 95 communicate with each other via a plurality of communication passages 96 formed on the bottom surface (plane) of the recess 92. On the bottom surface of the recess 92, the plurality of communication passages 96 are positioned so that each communication passage 96 coaxially communicates with the corresponding outlet 11 out when the entire end portion of the support substrate 10 is inserted into the recess 92 of the manifold 90. Each is arranged.

  As shown in FIG. 24, the entire end portion of the support substrate 10 is formed so that the plane on which the pair of upper and lower outlets 11 out and 11 out is formed at the end portion is in contact with the bottom surface (plane) of the recess 92 of the manifold 90. It is inserted into the recess 92 of the manifold 90. As a result, each outflow port 11out communicates with the gas exhaust passage 95 by being coaxially connected to the corresponding communication passage 96. On the other hand, a space S <b> 1 is defined and formed by the groove 13 and the bottom surface of the recess 92. The space S1 communicates with the inflow port 11in formed in the bottom surface of the groove 13, and also communicates with the communication path 94 described above. As a result, the inflow port 11in communicates with the gas supply path 93. Note that, in a state where the manifold 90 is attached to the support substrate 10, a lid member 97 as shown in FIG. 23 is actually attached to partition the gas supply path 93 from the outside.

  Here, a gas seal function is provided at a portion (abutment surface) where the plane where the pair of upper and lower outlets 11out and 11out are formed at the end portion of the support substrate 10 and the bottom surface (plane) of the recess 92 of the manifold 90 abuts. Can be reliably achieved. As a result, mixing of the gas flowing in from the inlet 11in and the exhaust gas flowing out of the outlet 11out can be prevented. According to this configuration, even if the overall thickness of the support substrate 10 is small and the adjacent inlet 11in and outlet 11out are close to each other in the thickness direction, the above-described gas sealing function can be easily achieved. .

As described above, the connection structure shown in FIGS. 22 to 24 is “the end of one side in the longitudinal direction of the support substrate, and the inlet and outlet of the gas flow path formed inside the support substrate are formed. A connection structure between an end and a manifold having a function of supplying fuel gas to the inlet and a function of collecting fuel gas exhausted from the outlet and attached to the end;
In the end portion of the support substrate, the inflow port is formed in a plane located on the inner side in the longitudinal direction from the plane in which the outflow port is formed,
On the attachment surface of the manifold, a recess for inserting the end of the support substrate is formed,
The manifold is formed with a gas supply path for supplying fuel gas introduced from the outside to the inlet, and a gas exhaust path for recovering exhaust gas discharged from the outlet,
The recess and the gas supply path communicate with each other via a first communication path formed on a side surface of the recess, and the recess and the gas exhaust path are formed on a plane that is a bottom surface of the recess. It communicates through two communication paths,
In a state where the end and the manifold are connected by inserting the end of the support substrate into the recess of the manifold, the plane on which the outflow port is formed at the end of the support substrate is the manifold. A space that is in contact with a flat surface that is the bottom surface of the recess, the second communication path communicates with the outlet, and is defined and formed by an end portion of the support substrate and the recess, and the inlet and the first A connection structure that communicates with the communication path. ".

  Even if the manifold 90 shown in FIG. 26 is attached to one end in the longitudinal direction of the support substrate 10 having the end shape shown in FIG. 25, the same operation and effect can be obtained. That is, on the end surface on one side in the longitudinal direction of the support substrate 10 shown in FIG. 25, the protruding portion 14 that extends to both ends in the width direction at the central portion in the thickness direction within a range that does not interfere with the pair of upper and lower outlets 11out, 11out. Is formed. The cross section of the protrusion 14 has a rectangular shape. An inflow port 11 in is formed on the top surface (plane) of the protruding portion 14. That is, the inflow port 11in is formed on a plane located on the outer side in the longitudinal direction from the plane on which the upper and lower pair of outflow ports 11out and 11out are formed.

  26, a concave portion 92 for inserting the entire end portion of the support substrate 10 and a gas exhaust passage 95 for collecting the exhaust gas discharged from the outlet 11out are formed on the mounting surface 91 of the manifold 90 shown in FIG. ing. The recess 92 and the gas exhaust passage 95 communicate with each other through a communication path 96 formed in a part (two places) of the side surface of the recess 92.

  Further, the manifold 90 is formed with a gas supply path 93 for supplying the fuel gas introduced from the outside to the inflow port 11in. The recess 92 and the gas supply passage 93 communicate with each other via a plurality of communication passages 94 formed on the bottom surface (plane) of the recess 92. On the bottom surface of the recess 92, the plurality of communication passages 94 are positioned so that each communication passage 94 is coaxially connected to the corresponding inlet 11in when the entire end portion of the support substrate 10 is inserted into the recess 92 of the manifold 90. Each is arranged.

  As shown in FIG. 27, the entire end portion of the support substrate 10 has a concave portion 92 of the manifold 90 such that a plane on which the inflow port 11 in is formed contacts the bottom surface (plane) of the concave portion 92 of the manifold 90. Inserted into. As a result, each inflow port 11in is coaxially connected to the corresponding communication path 94, thereby communicating with the gas supply path 93. On the other hand, spaces S <b> 2 and S <b> 2 are defined and formed by the end surface of the support substrate 10 including the protrusion 14 and the recess 92. The spaces S2 and S2 communicate with the pair of upper and lower outlets 11out and 11out, respectively, and also communicate with the communication path 96 described above. As a result, the pair of upper and lower outlets 11out and 11out communicate with the gas exhaust path 95. In the state where the manifold 90 is attached to the support substrate 10, a lid member 97 as shown in FIG. 26 is actually attached to partition the gas exhaust path 95 from the outside.

  Here, the gas sealing function is reliably achieved at the portion (contact surface) where the plane where the inflow port 11in is formed at the end of the support substrate 10 and the bottom surface (plane) of the recess 92 of the manifold 90 abuts. obtain. As a result, mixing of the gas flowing in from the inlet 11in and the exhaust gas flowing out of the outlet 11out can be prevented. Even with this configuration, even if the total thickness of the support substrate 10 is small and the positions of the adjacent inflow port 11in and the outflow port 11out in the thickness direction are close to each other, the above-described gas sealing function can be easily achieved.

As described above, the connection structure shown in FIGS. 25 to 27 is “the end of one side in the longitudinal direction of the support substrate and the inlet and outlet of the gas channel formed inside the support substrate are formed. A connection structure between an end and a manifold having a function of supplying fuel gas to the inlet and a function of collecting fuel gas exhausted from the outlet and attached to the end;
In the end portion of the support substrate, the inflow port is formed in a plane located outside in a longitudinal direction from the plane in which the outflow port is formed,
On the attachment surface of the manifold, a recess for inserting the end of the support substrate is formed,
The manifold is formed with a gas supply path for supplying fuel gas introduced from the outside to the inlet, and a gas exhaust path for recovering exhaust gas discharged from the outlet,
The recess and the gas exhaust path communicate with each other via a first communication path formed on a side surface of the recess, and the recess and the gas supply path are formed on a plane that is a bottom surface of the recess. It communicates through two communication paths,
In a state where the end portion and the manifold are connected by inserting the end portion of the support substrate into the concave portion of the manifold, a plane on which the inflow port is formed at the end portion of the support substrate is a portion of the manifold. A space that is in contact with a flat surface that is a bottom surface of the recess, the second communication path communicates with the inflow port, and is defined and formed by an end portion of the support substrate and the recess, and the first and second outlets. A connection structure that communicates with the communication path. ".

  In the above embodiment, the fuel electrode 20 is formed (laminated) on the main surface of the support substrate 10, and the interconnector 30 is formed (laminated) on the outer surface of the fuel electrode 20. As shown, the fuel electrode 20 may be embedded in a recess formed on the main surface of the support substrate 10, and the interconnector 30 may be embedded in a recess formed on the outer surface of the fuel electrode 20. Hereinafter, the main differences of the form shown in FIGS. 28-30 with respect to the said embodiment are demonstrated easily.

  In the form shown in FIGS. 28 to 30, a plurality of recesses 12 are formed on the main surface (upper and lower surfaces) of the support substrate 10 at predetermined intervals in the longitudinal direction (see FIG. 30). Each recess 12 has a bottom wall made of the material of the support substrate 10 and side walls closed in the circumferential direction made of the material of the support substrate 10 (two side walls along the longitudinal direction and two side walls along the width direction). ) And a rectangular parallelepiped depression defined by The entire fuel electrode current collector 21 is embedded (filled) in each recess 12. Therefore, each fuel electrode current collector 21 has a rectangular parallelepiped shape.

  A recess 21 a is formed on the upper surface (outer surface) of each fuel electrode current collector 21. Each recess 21a has a rectangular parallelepiped shape defined by a bottom wall made of the material of the fuel electrode current collector 21 and side walls closed in the circumferential direction (two side walls along the longitudinal direction and two side walls along the width direction). It is a depression. Of the side walls closed in the circumferential direction, two side walls along the longitudinal direction are made of the material of the support substrate 10, and two side walls along the width direction are made of the material of the fuel electrode current collector 21.

  The entire anode active portion 22 is embedded (filled) in each recess 21a. Accordingly, each fuel electrode active portion 22 has a rectangular parallelepiped shape. A fuel electrode 20 is configured by the fuel electrode current collector 21 and the fuel electrode active unit 22. The fuel electrode 20 (fuel electrode current collector 21 + fuel electrode active part 22) is a fired body made of a porous material having electron conductivity. The two side surfaces and the bottom surface along the width direction of each anode active portion 22 are in contact with the anode current collecting portion 21 in the recess 21a.

  A recess 21b is formed in a portion of the upper surface (outer surface) of each fuel electrode current collector 21 excluding the recess 21a. Each recess 21b includes a bottom wall made of a material of the fuel electrode current collector 21 and a circumferentially closed side wall made of the material of the fuel electrode current collector 21 (two side walls along the longitudinal direction). And two side walls along the width direction).

  An interconnector 30 is embedded (filled) in each recess 21b. Accordingly, each interconnector 30 has a rectangular parallelepiped shape. The interconnector 30 is a fired body made of a dense material having electronic conductivity. The four side walls (two side walls along the longitudinal direction and two side walls along the width direction) and the bottom surface of each interconnector 30 are in contact with the fuel electrode current collector 21 in the recess 21b.

  The upper surface (outer surface) of the fuel electrode 20 (the fuel electrode current collector 21 and the fuel electrode active unit 22), the upper surface (outer surface) of the interconnector 30, and the main surface of the support substrate 10 form one plane (recessed portion). The same plane as the main surface of the support substrate 10 when 12 is not formed) is formed. That is, no step is formed between the upper surface of the fuel electrode 20, the upper surface of the interconnector 30, and the main surface of the support substrate 10.

The fuel electrode active part 22 may be composed of, for example, NiO (nickel oxide) and YSZ (8YSZ) (yttria stabilized zirconia). Or you may comprise from NiO (nickel oxide) and GDC (gadolinium dope ceria). The fuel electrode current collector 21 can be composed of, for example, NiO (nickel oxide) and YSZ (8YSZ) (yttria stabilized zirconia). Alternatively, it may be composed of NiO (nickel oxide) and Y ₂ O ₃ (yttria), or may be composed of NiO (nickel oxide) and CSZ (calcia stabilized zirconia). The thickness of the anode active portion 22 is 5 to 30 μm, and the thickness of the anode current collecting portion 21 (that is, the depth of the recess 12) is 50 to 500 μm.

  As described above, the fuel electrode current collector 21 includes a substance having electronic conductivity. The fuel electrode active part 22 includes a substance having electron conductivity and a substance having oxidative ion (oxygen ion) conductivity. The “volume ratio of the substance having oxidative ion conductivity relative to the total volume excluding the pore portion” in the anode active portion 22 is “the oxidative ion conductivity relative to the entire volume excluding the pore portion” in the anode current collecting portion 21. Greater than the volume fraction of the substance having

The interconnector 30 can be composed of, for example, LaCrO ₃ (lanthanum chromite). Alternatively, it may be composed of (Sr, La) TiO ₃ (strontium titanate). The thickness of the interconnector 30 is 10 to 100 μm.

  The entire surface excluding the central portion in the longitudinal direction of each portion where the plurality of interconnectors 30 are formed on the outer peripheral surface extending in the longitudinal direction of the support substrate 10 in a state where the fuel electrode 20 and the interconnector 30 are embedded in the respective recesses 12. Is covered with a solid electrolyte membrane 40. The solid electrolyte membrane 40 is a fired body made of a dense material having ionic conductivity and not electron conductivity. The solid electrolyte membrane 40 can be made of, for example, YSZ (8YSZ) (yttria stabilized zirconia). Or you may comprise from LSGM (lantern gallate). The thickness of the solid electrolyte membrane 40 is 3 to 50 μm.

  That is, the entire outer peripheral surface extending in the longitudinal direction of the support substrate 10 in a state where the fuel electrode 20 is embedded in each recess 12 is covered with a dense layer composed of the interconnector 30 and the solid electrolyte membrane 40. This dense layer exhibits a gas sealing function that prevents mixing of the fuel gas flowing in the space inside the dense layer and the air flowing in the space outside the dense layer.

  As shown in FIG. 28, in this example, the solid electrolyte membrane 40 covers the upper surface of the fuel electrode 20, both side ends in the longitudinal direction on the upper surface of the interconnector 30, and the main surface of the support substrate 10. Here, as described above, no step is formed between the upper surface of the fuel electrode 20, the upper surface of the interconnector 30, and the main surface of the support substrate 10. Therefore, the solid electrolyte membrane 40 is flattened. As a result, compared with the case where a step is formed in the solid electrolyte membrane 40, the generation of cracks in the solid electrolyte membrane 40 due to stress concentration can be suppressed, and the gas sealing function of the solid electrolyte membrane 40 is reduced. Can be suppressed.

  An air electrode 60 is formed on the upper surface of a portion in contact with each fuel electrode active part 22 in the solid electrolyte membrane 40 via a reaction preventing film 50. The reaction preventing film 50 is a fired body made of a dense material, and the air electrode 60 is a fired body made of a porous material having electron conductivity. The shape of the reaction preventing film 50 and the air electrode 60 viewed from above is substantially the same rectangle as the fuel electrode active part 22.

The reaction preventing film 50 can be made of, for example, GDC = (Ce, Gd) O ₂ (gadolinium-doped ceria). The thickness of the reaction preventing film 50 is 3 to 50 μm. The air electrode 60 can be made of, for example, LSCF = (La, Sr) (Co, Fe) O ₃ (lanthanum strontium cobalt ferrite). Alternatively, from LSF = (La, Sr) FeO ₃ (lanthanum strontium ferrite), LNF = La (Ni, Fe) O ₃ (lanthanum nickel ferrite), LSC = (La, Sr) CoO ₃ (lanthanum strontium cobaltite), etc. It may be configured. Further, the air electrode 60 may be configured by two layers of a first layer (inner layer) made of LSCF and a second layer (outer layer) made of LSC. The thickness of the air electrode 60 is 10 to 100 μm.

  The reaction preventing film 50 is interposed because the YSZ in the solid electrolyte film 40 and the Sr in the air electrode 60 react with each other in the SOFC during the production or operation of the SOFC, and the solid electrolyte film 40 and the air electrode. This is to suppress the occurrence of a phenomenon in which a reaction layer having a large electric resistance is formed at the interface with the substrate 60.

  Here, the laminated body formed by laminating the fuel electrode 20, the solid electrolyte membrane 40, the reaction preventing membrane 50, and the air electrode 60 corresponds to the “power generation element portion A” (see FIG. 28). In other words, a plurality (four in this example) of power generating element portions A are arranged on the upper surface of the support substrate 10 at a predetermined interval in the longitudinal direction.

  For each pair of adjacent power generation element portions A and A, the air electrode 60 of one power generation element portion A (on the left side in FIG. 28) and the interconnector of the other power generation element portion A (on the right side in FIG. 28). The air electrode current collecting film 70 is formed on the upper surfaces of the air electrode 60, the solid electrolyte film 40, and the interconnector 30. The air electrode current collector film 70 is a fired body made of a porous material having electron conductivity. The shape of the air electrode current collector film 70 as viewed from above is a rectangle.

The air electrode current collector film 70 can be made of, for example, LSCF = (La, Sr) (Co, Fe) O ₃ (lanthanum strontium cobalt ferrite). Alternatively, LSC = (La, Sr) CoO ₃ (lanthanum strontium cobaltite) may be used. Or you may comprise from Ag (silver) and Ag-Pd (silver palladium alloy). The thickness of the air electrode current collector film 70 is 50 to 500 μm.

  By forming each air electrode current collecting film 70 in this way, the air electrode 60 of one power generation element part A (on the left side in FIG. 28) of each pair of adjacent power generation element parts A and A, The other fuel electrode 20 (in particular, the fuel electrode current collector 21) of the power generating element part A (on the right side in FIG. 28) is connected via the “air electrode current collector film 70 and interconnector 30” having electronic conductivity. Are electrically connected. As a result, a plurality (four in this example) of power generation element portions A arranged on the upper surface of the support substrate 10 are electrically connected in series. Here, the “air electrode current collector film 70 and the interconnector 30” having electronic conductivity correspond to the “electrical connection part”.

  The interconnector 30 corresponds to the “first portion made of a dense material” in the “electrical connection portion” and has a porosity of 10% or less. The air electrode current collecting film 70 corresponds to the “second portion made of a porous material” in the “electrical connection portion”, and has a porosity of 20 to 60%.

  As described above, in the form shown in FIGS. 28 to 30, each of the plurality of recesses 12 for embedding the fuel electrode 20 has a side wall closed in the circumferential direction made of the material of the support substrate 10 over the entire circumference. Yes. In other words, the support body 10 is formed with a frame surrounding each recess 12. Therefore, this structure is not easily deformed when the support substrate 10 receives an external force.

  Further, the support substrate 10 and the embedded member are co-sintered in a state in which the members such as the fuel electrode 20 and the interconnector 30 are filled and embedded in the recesses 12 of the support substrate 10 without gaps. Therefore, a sintered body having high bondability between members and high reliability can be obtained.

  Further, the interconnector 30 is embedded in a recess 21b formed on the outer surface of the fuel electrode current collector 21, and as a result, the four sidewalls of the rectangular parallelepiped interconnector 30 (two sidewalls along the longitudinal direction, width) Two side walls along the direction) and the bottom face are in contact with the anode current collector 21 in the recess 21b. Therefore, the fuel electrode 20 (the current collector 21) and the interconnector 30 are compared to the case where a configuration in which the rectangular parallelepiped interconnector 30 is laminated (contacted) on the outer plane of the fuel electrode current collector 21 is employed. The area of the interface with can be increased. Therefore, the electronic conductivity between the fuel electrode 20 and the interconnector 30 can be increased, and as a result, the power generation output of the fuel cell can be increased.

  Further, in the above-described embodiment, a plurality of power generation element portions A are provided on each of the upper and lower surfaces of the flat support substrate 10. Thereby, compared with the case where a plurality of power generation element portions are provided only on one side surface of the support substrate, the number of power generation element portions in the structure can be increased, and the power generation output of the fuel cell can be increased.

  In the above embodiment, the solid electrolyte membrane 40 covers the outer surface of the fuel electrode 20, both end portions in the longitudinal direction of the outer surface of the interconnector 30, and the main surface of the support substrate 10. Here, no step is formed between the outer surface of the fuel electrode 20, the outer surface of the interconnector 30, and the main surface of the support substrate 10. Therefore, the solid electrolyte membrane 40 is flattened. As a result, compared with the case where a step is formed in the solid electrolyte membrane 40, the generation of cracks in the solid electrolyte membrane 40 due to stress concentration can be suppressed, and the gas sealing function of the solid electrolyte membrane 40 is reduced. Can be suppressed.

  DESCRIPTION OF SYMBOLS 10 ... Support substrate, 11 ... Fuel gas flow path, 11a ... Outbound part, 11b ... Return path part, 11c ... Intermediate part, 11in ... Inlet, 11out ... Outlet, 12 ... Recessed part, 20 ... Fuel electrode, 21 ... Fuel electrode Current collecting part, 21a, 21b ... concave part, 22 ... fuel electrode active part, 30 ... interconnector, 40 ... solid electrolyte membrane, 50 ... reaction preventing film, 60 ... air electrode, 70 ... air electrode current collecting film, A ... power generation Element part

Claims (5)

A flat plate-like porous support substrate having a longitudinal direction, in which a gas flow path is formed by integral firing; and
Disposed on the main surface of the plate-shaped support substrate, at least the inner electrode, the solid electrolyte, and the power generating element of the multiple outer electrodes ing are stacked,
In a fuel cell structure comprising:
An inlet and an outlet of the gas channel are formed at one end of the support substrate in the longitudinal direction, and the gas channel extends from the inlet to the other side of the support substrate in the longitudinal direction. An outward path, a return path extending from the other side in the longitudinal direction of the support substrate to the outlet, an end on the other side in the longitudinal direction of the forward path, and an end on the other side in the longitudinal direction of the return path An intermediate portion for connecting, the return path portion and the forward path portion are formed at different positions in the thickness direction of the support substrate,
The power generating element portions are respectively disposed at a plurality of locations that are located apart from each other along the longitudinal direction of only the first main surface of the first and second main surfaces parallel to each other of the flat support substrate. The one inner electrode and the other outer electrode of the adjacent power generation element portions are electrically connected,
The forward path portion of the gas flow path extends from the inflow port to the other side in the longitudinal direction of the support substrate on the side close to the second main surface in the thickness direction of the support substrate, An intermediate portion extends from a side close to the second main surface in the thickness direction of the support substrate to a side close to the first main surface, and the return path portion of the gas flow path extends in the thickness direction. A fuel cell structure extending from the other side in the longitudinal direction of the support substrate to the outflow port on a side close to one main surface. A flat plate-like porous support substrate having a longitudinal direction, in which a gas flow path is formed by integral firing; and
Disposed on the main surface of the plate-shaped support substrate, at least the inner electrode, the solid electrolyte, and the power generating element of the multiple outer electrodes ing are stacked,
In a fuel cell structure comprising:
An inlet and an outlet of the gas channel are formed at one end of the support substrate in the longitudinal direction, and the gas channel extends from the inlet to the other side of the support substrate in the longitudinal direction. An outward path, a return path extending from the other side in the longitudinal direction of the support substrate to the outlet, an end on the other side in the longitudinal direction of the forward path, and an end on the other side in the longitudinal direction of the return path An intermediate portion for connecting, the return path portion and the forward path portion are formed at different positions in the thickness direction of the support substrate,
The power generating element portions are respectively disposed at a plurality of locations that are located apart from each other along the longitudinal direction of only the first main surface of the first and second main surfaces parallel to each other of the flat support substrate. The one inner electrode and the other outer electrode of the adjacent power generation element portions are electrically connected,
The forward path portion of the gas flow path extends from the inlet to the other side in the longitudinal direction of the support substrate on the side close to the first main surface in the thickness direction of the support substrate, An intermediate portion extends from a side close to the first main surface in the thickness direction of the support substrate to a side close to the second main surface, and the return path portion of the gas flow path extends in the thickness direction. 2. A fuel cell structure extending from the other side in the longitudinal direction of the support substrate to the outflow port on the side close to the main surface. The fuel cell structure according to claim 1,
A fuel cell structure in which an inner wall of the forward path portion of the gas flow path is made of a material having a lower porosity than the porous material constituting the support substrate. The fuel cell structure according to claim 3, wherein
The fuel cell structure includes a catalyst component that promotes a reforming reaction of the fuel gas. A flat plate-like porous support substrate having a longitudinal direction, in which a gas flow path is formed by integral firing; and
A plurality of power generating element portions each provided at a plurality of positions separated from each other on the main surface of the flat support substrate, and a laminate of at least an inner electrode, a solid electrolyte, and an outer electrode;
One or a plurality of electrical connections that are respectively provided between one set or a plurality of sets of adjacent power generation element portions and electrically connect one inner electrode and the other outer electrode of the adjacent power generation element portions And
In a fuel cell structure comprising:
Each of the electrical connection portions includes a first portion made of a dense material, and a second portion made of a porous material connected to the first portion,
A first recess having a bottom wall made of the material of the support substrate and a side wall made of the material of the support substrate over the entire circumference at the plurality of locations on the main surface of the flat support substrate. Each formed,
In each of the first recesses, a corresponding inner electrode of the power generation element portion is embedded,
The first portion of the corresponding electrical connection portion is embedded in the second recess formed on the outer surface of each embedded inner electrode,
Each of the second recesses in which the corresponding first portion of the electrical connection portion is embedded is closed in the circumferential direction made of the material of the inner electrode and the bottom wall made of the material of the inner electrode. Having side walls,
An inlet and an outlet of the gas channel are formed at one end of the support substrate in the longitudinal direction, and the gas channel extends from the inlet to the other side of the support substrate in the longitudinal direction. An outward path, a return path extending from the other side in the longitudinal direction of the support substrate to the outlet, an end on the other side in the longitudinal direction of the forward path, and an end on the other side in the longitudinal direction of the return path A fuel cell structure in which the return path part and the forward path part are formed at different positions in the thickness direction of the support substrate.

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