JP2019061910A - Fuel battery cell and cell stack apparatus - Google Patents

Abstract

To provide a fuel battery cell which enables the increase in intensity, and a cell stack apparatus capable of suppressing gas leak.SOLUTION: A fuel battery cell (100) of the present invention is a fuel battery cell in which a bottom end part (101) is supported by a manifold (200). The fuel battery cell comprises: a support substrate (110) having an outer surface (112) configured of a porous material, and extending in an up-and-down direction, and a lower end face (116) connecting to a lower end of the outer surface (112); a power generation element part (120) provided on the outer surface (112); and a dense film (122) provided so that the outer surface (112) connecting to the lower end face (116) is partially exposed at the bottom end part (101) of the fuel battery cell (100). The support substrate (110) has a dense region resulting from impregnation from an exposed surface (112b) and at least portion of the lower face (116) with another material by 1.0 μm or more.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a fuel cell and a cell stack device.

  BACKGROUND Conventionally, there is known a cell stack device including a plurality of fuel cells, a manifold to which one end of the fuel cells is fixed, and a sealing material that fixes the fuel cells and the manifold. As such a cell stack device, for example, JP-A-2016-225035 (Patent Document 1) can be mentioned.

  The seal material of Patent Document 1 has an inner surface which is the inner space side of the manifold and an outer surface which is the other end side of the fuel cell, and the inner surface has a larger surface roughness than the outer surface. . Patent Document 1 discloses that cracking on the outer surface accompanied by gas leak is prevented by preferentially generating a crack on the inner surface having a large surface roughness.

JP, 2016-225035, A

  However, in the cell stack device of Patent Document 1, the inventor noted that there is a problem that the gas leak can not be sufficiently suppressed by the occurrence of the crack in the fuel cell. That is, the sealing material is a dense body for gas sealing, whereas the supporting substrate of the fuel cell is a porous body. For this reason, although the strength of the sealing material is high, since the supporting substrate is inferior in strength, the inventors have found that a crack is easily generated from the lower end portion of the fuel cell. When a crack is generated from the lower end of the fuel cell, there is a risk that a gas leak may occur.

  In view of the above problems, the present invention has an object to provide a fuel cell that improves the strength. Another object of the present invention is to provide a cell stack device that suppresses gas leakage.

  The inventor found that the problem that the gas leak can not be sufficiently suppressed in the cell stack device of Patent Document 1 is due to the fuel cell having lower strength than the sealing material. When the fuel cell has low strength, when the thermal stress is generated due to thermal expansion and thermal contraction, the lower end portion of the fuel cell is preferentially cracked rather than the sealing material. When this crack reaches the outer surface of the fuel cell, it becomes a passage connecting the inner space of the manifold and the outer space of the manifold. Therefore, the fuel gas introduced into the inner space leaks from the inner space to the outer space, and a gas leak occurs. Therefore, the inventor of the present invention completed the present invention by obtaining an idea of increasing the strength of a portion where a crack is likely to occur in the fuel cell due to thermal stress.

  That is, the fuel cell of the present invention is a fuel cell having a lower end supported by a manifold, which is made of a porous material and has an outer surface extending in the vertical direction and a lower end connected to the lower end of the outer surface. In the lower end portion of a fuel cell having a support substrate having an end face, an outer surface, a fuel electrode, an electrolyte, and an air electrode, a part of the outer surface connected to the lower end face is exposed. And the supporting substrate is a dense region impregnated with other material by 1.0 μm or more from the exposed surface exposed from the dense film on the outer surface, and at least a part of the lower end surface. Have.

  In the lower end portion supported by the manifold of the fuel cell, a crack is easily generated due to thermal stress in the region near the lower end surface. According to the fuel cell of the present invention, at least a portion of the lower end surface and the exposed surface located in the area near the lower end surface form a dense region of 1.0 μm or more higher in strength than the porous material constituting the support substrate It is done. Therefore, the strength of the region near the lower end surface can be improved. Therefore, the present invention can provide a fuel cell with improved strength.

  Preferably, in the fuel cell of the present invention, the other material is glass. Here, the glass is any of crystallized glass which is crystallized by heat treatment, amorphous glass, and partially crystallized glass which is partially crystallized.

  According to this configuration, it is possible to easily realize a fuel cell comprising a support substrate having a dense region in which glass is disposed in the pores of the porous material.

  Preferably, in the fuel cell of the present invention, the porosity of the porous material forming the support substrate is 20% or more and 60% or less.

  Since the supporting substrate made of the porous material having the porosity in the above range has low strength, it is easily cracked. For this reason, the effect by having a precise | minute area | region is remarkable.

  A cell stack device according to the present invention includes the fuel cell according to any one of the above, a manifold for supporting the lower end portion of the fuel cell, and a bonding material for bonding the manifold and the fuel cell.

  According to the cell stack device of the present invention, since the fuel cell in which the dense region is formed in the region near the lower end surface is provided, the strength of the region near the lower end surface can be improved. Thereby, even if thermal stress is applied, it is possible to suppress cracks originating from the region near the lower end surface of the support substrate. For this reason, since the crack of the fuel cell can be suppressed, the crack connecting the internal space of the manifold and the external space of the manifold can be suppressed. Therefore, the present invention can provide a cell stack device that suppresses gas leaks.

  Preferably, in the cell stack device of the present invention, the dense region is formed by arranging the same material as the material forming the bonding material in at least a part of the pores of the porous material forming the support substrate.

  The anchor effect is obtained by impregnating the region near the lower end face of the support substrate with the same material as the material constituting the bonding material. Thus, the bonding strength between the bonding material and the fuel cell can be improved.

  As described above, the present invention can provide a fuel cell with improved strength. Furthermore, the present invention can provide a cell stack device that suppresses gas leaks.

FIG. 1 is a perspective view showing a cell stack device of Embodiment 1; FIG. 1 is a cross-sectional view showing a cell stack device of Embodiment 1; FIG. 1 is a cross-sectional view showing a cell stack device of Embodiment 1; FIG. 1 is a perspective view showing a fuel cell of Embodiment 1; FIG. 1 is a cross-sectional view showing a fuel cell of Embodiment 1; FIG. 2 is an enlarged cross-sectional view showing a cell stack device of Embodiment 1; FIG. 2 is an enlarged cross-sectional view showing a fuel cell of Embodiment 1; FIG. 7 is a cross-sectional view showing the method of manufacturing the cell stack device of the first embodiment. FIG. 7 is a cross-sectional view showing the method of manufacturing the cell stack device of the first embodiment. FIG. 7 is a schematic view showing a fuel cell and a bonding material that constitute the cell stack device of Embodiment 2. FIG. 10 is an enlarged cross-sectional view showing a cell stack device of Embodiment 2; FIG. 6 is an enlarged cross-sectional view showing a fuel cell of Embodiment 2; It is a schematic diagram which shows the fuel cell which comprises the cell stack apparatus of Embodiment 3, and a joining material. FIG. 16 is a schematic view showing a fuel cell and a bonding material that constitute the cell stack device of the fourth embodiment. FIG. 18 is a schematic view showing a fuel cell and a bonding material that constitute the cell stack device of the fifth embodiment. FIG. 21 is a schematic view showing a fuel cell and a bonding material that constitute the cell stack device of the sixth embodiment. FIG. 21 is a schematic view showing a fuel cell and a bonding material that constitute the cell stack device of the seventh embodiment. It is a schematic diagram which shows the fuel cell which comprises the cell stack apparatus of a comparative example, and a joining material.

  Hereinafter, embodiments of the present invention will be described based on the drawings. Each of the x-axis direction, the y-axis direction, and the z-axis direction in each drawing corresponds to the height direction, the short direction (width direction), and the longitudinal direction of the manifold. Further, each of the x-axis direction, the y-axis direction, and the z-axis direction in each drawing corresponds to the longitudinal direction, the lateral direction (width direction), and the thickness direction of each fuel cell and the support substrate. Further, “upper” and “lower” in the present specification are based on the height direction (x-axis direction) of the manifold when the manifold and the cell stack device are mounted on a horizontal surface.

Embodiment 1
A cell stack device and a fuel cell according to an embodiment of the present invention will be described with reference to FIGS. 1 to 6. The cell stack device and the fuel cell of Embodiment 1 are used for a solid oxide fuel cell (SOFC).

[Cell stack device]
As shown in FIGS. 1 to 3, the cell stack device 1 includes a plurality of fuel cells 100, a manifold 200, and a first bonding material 300. Each fuel cell 100 is supported by a manifold 200. The first bonding material 300 bonds each fuel cell 100 with the manifold 200.

[Fuel cell]
As shown in FIGS. 1 to 3, the fuel cells 100 extend upward from the manifold 200. Specifically, each fuel cell 100 extends upward from the top wall 230 of the manifold 200. The lower end portion 101 of the fuel cell 100 is inserted into the insertion hole 231 of the manifold 200. When the lower end portion 101 of the fuel cell 100 is inserted into the insertion hole 231, a gap is formed between the outer peripheral surface of the lower end portion 101 of the fuel cell 100 and the inner wall surface of the insertion hole 231. There is. The first bonding material 300 is filled in the gap. For this reason, the lower end portion 101 of the fuel cell 100 is fixed to the manifold 200. On the other hand, the upper end portion 102 of the fuel cell 100 is a free end. The fuel cells 100 are supported in a cantilever state by the manifold 200 and are self-supporting.

  The fuel cells 100 are spaced apart from each other along the longitudinal direction of the manifold 200. As shown in FIG. 2, the fuel cells 100 are electrically connected to each other via the first current collecting member 4. The first current collecting member 4 is disposed between the fuel cells 100 and connects the adjacent fuel cells 100. The first current collecting member 4 is joined to each fuel cell 100 by the second joining material 5. The first current collecting member 4 is formed of a conductive material. For example, the first current collecting member 4 is formed of a sintered body or metal of oxide ceramic.

  As shown in FIGS. 2 to 6, the fuel cell 100 includes a support substrate 110, a plurality of power generation element units 120, and a dense film 122. Each power generation element unit 120 is supported on both sides of the support substrate 110. Each power generation element unit 120 may be supported only on one side of the support substrate 110. The respective power generation element units 120 are spaced apart from each other in the longitudinal direction of the fuel cell 100. That is, the fuel cell 100 according to the present embodiment is a so-called horizontal stripe type fuel cell.

  The respective power generation element units 120 are electrically connected to each other by the electrical connection unit 160 (see FIG. 5). Further, on the side of the upper end portion 102 of the fuel cell 100, the power generation element portion 120 formed on one surface of the support substrate 110 and the power generation element portion 120 formed on the other surface are the second current collecting members 6 (see FIG. 2). Electrically connected by The respective power generation element units 120 are connected in series.

<Power generation element part>
As shown in FIG. 5, each power generation element unit 120 includes a fuel electrode 130, an electrolyte 140, and an air electrode 150. Each power generation element unit 120 further includes a reaction prevention film 121.

  The fuel electrode 130 is a sintered body made of a porous material having electron conductivity. The fuel electrode 130 has a fuel electrode current collector 131 and a fuel electrode active part 132. The anode collecting portion 131 is disposed in a first recess 112 a formed in the outer surface 112 of the support substrate 110 described later. Each anode collecting portion 131 has a second recess 131a and a third recess 131b. The anode active portion 132 is disposed in the second recess 131a.

The fuel electrode current collecting portion 131 may be made of, for example, NiO and YSZ, may be made of NiO and Y ₂ O ₃ , or may be made of NiO and CSZ. The thickness of the anode collecting portion 131, that is, the depth of the first concave portion 112a is, for example, 50 to 500 μm.

The fuel electrode active portion 132 may be made of, for example, NiO and YSZ, or may be made of NiO and GDC = (Ce, Gd) O ₂ (gadolinium-doped ceria). The thickness of the fuel electrode active portion 132 is, for example, 5 to 30 μm.

  The electrolyte 140 is disposed to cover the fuel electrode 130. Specifically, the electrolyte 140 extends in the longitudinal direction of the fuel cell 100 from one interconnector 161 to another interconnector 161. That is, in the longitudinal direction of the fuel cell 100, the electrolytes 140 and the interconnectors 161 are alternately arranged.

  The electrolyte 140 is a sintered body composed of a dense material having ion conductivity and no electron conductivity. The electrolyte 140 may be made of, for example, YSZ or may be made of LSGM (lanthanum gallate). The thickness of the electrolyte 140 is, for example, 3 to 50 μm.

  The reaction preventing film 121 is a sintered body made of a dense material, and in a plan view, has substantially the same shape as the anode active portion 132 and is disposed at substantially the same position as the anode active portion 132. The reaction preventing film 121 causes the reaction layer YSZ in the electrolyte 140 and Sr (strontium) in the air electrode 150 to react to form a reaction layer having a large electric resistance at the interface between the electrolyte 140 and the air electrode 150. It is provided to suppress. The reaction prevention film 121 is made of, for example, GDC. The thickness of the reaction prevention film 121 is, for example, 3 to 50 μm.

The air electrode 150 is disposed on the reaction prevention film 121. The air electrode 150 is a sintered body made of a porous material having electron conductivity. The air electrode 150 is, for example, LSCF = (La, Sr) (Co, Fe) O ₃ (lanthanum strontium cobalt ferrite), LSF = (La, Sr) FeO ₃ (lanthanum strontium ferrite), LNF = La (Ni, Fe) ) _{O 3} (lanthanum nickel ferrite), LSC = (La, Sr ) CoO 3 ( may be composed of lanthanum strontium cobaltite) or the like. In addition, the air electrode 150 may be configured by two layers of a first layer (inner layer) composed of LSCF and a second layer (outer layer) composed of LSC. The thickness of the air electrode 150 is, for example, 10 to 100 μm.

The electrical connection unit 160 is configured to electrically connect adjacent power generation element units 120. The electrical connection portion 160 has an interconnector 161 and an air electrode current collecting film 162. The interconnector 161 is disposed in the third recess 131 b. The interconnector 161 is a fired body composed of a dense material having electron conductivity. The interconnector 161 may be made of, for example, LaCrO ₃ (lanthanum chromite) or (Sr, La) TiO ₃ (strontium titanate). The thickness of the interconnector 161 is, for example, 10 to 100 μm.

The cathode current collecting film 162 is disposed to extend between the interconnector 161 of the adjacent power generation element unit 120 and the cathode 150. The air electrode current collecting film 162 is a sintered body composed of a porous material having electron conductivity. Air electrode current film 162, for example, LSCF = (La, Sr) (Co, Fe) may be composed of _{O 3, LSC = (La,} Sr) may be composed of CoO _3, Ag You may be comprised from (silver), Ag-Pd (silver palladium alloy). The thickness of the air electrode current collecting film 162 is, for example, 50 to 500 μm.

<Dense membrane>
As shown in FIGS. 6 and 7, the dense film 122 is provided at the lower end portion 101 of the support substrate 110 so that a part of the outer surface 112 connected to the lower end surface 116 is exposed. That is, on the outer surface 112 of the lower end portion 101, the dense film 122 is provided at least at a portion separated from the lower end surface 116. Specifically, the lower end portion 101 of the support substrate 110 is covered by the dense film 122 except the region R near the lower end surface. As shown in FIG. 7, the lower end surface vicinity region R is a region extending upward from the lower end surface 116 by a predetermined distance L. The predetermined distance L is a maximum distance from the lower end surface 116, and for example, is more than 0 and 3.0 mm or less.

  The dense film 122 exerts a gas seal function to prevent mixing of the fuel gas flowing in the space inside the dense film 122 and the air flowing in the space outside the dense film 122. In order to exert the gas sealing function, the porosity of the dense film 122 is smaller than the porosity of the porous material constituting the support substrate 110, and is, for example, 10% or less. Also, the dense film 122 is made of insulating ceramic. The outer surface of the dense film 122 is a smooth surface.

  The dense film 122 is electrically connected to the power generation element portion 120 formed on the lower end portion 101 side. Specifically, as shown in FIG. 6, the dense film 122 is electrically connected to the electrical connection portion 160. The dense film 122 extends from the space between the air electrode current collecting film 162 and the support substrate 110 toward the proximal side.

  In detail, the dense film 122 can be configured by the electrolyte 140 and the reaction prevention film 121 described above. An electrolyte 140 constituting the dense film 122 covers the support substrate 110 and extends from the interconnector 161 to the vicinity of the lower end surface 116 of the support substrate 110. In addition, the reaction prevention film 121 constituting the dense film 122 is disposed between the electrolyte 140 and the air electrode current collection film 162. The reaction prevention film 121 extends from the interconnector 161 to the vicinity of the lower end surface 116 of the support substrate 110. In the present embodiment, the electrolyte 140 extends to a region R near the lower end surface below the reaction prevention film 121. The dense film 122 may be composed of only the electrolyte 140 or may be composed of materials other than the electrolyte 140 and the reaction preventing film 121.

<Support substrate>
The support substrate 110 internally includes a plurality of gas flow paths 111 extending in the longitudinal direction (vertical direction) of the fuel cell 100. The gas flow passage 111 communicates with the internal space of the manifold 200 through the insertion hole 231 of the manifold 200.

  The longitudinal direction of the support substrate 110 is the same as the longitudinal direction of the fuel cell 100. The respective gas channels 111 extend substantially parallel to one another. Each gas passage 111 is open at both ends in the longitudinal direction of the fuel cell 100.

  The support substrate 110 has an outer surface 112 extending in the vertical direction, a lower end surface 116 connected to the lower end of the outer surface 112, and an upper end surface 117 connected to the upper end of the outer surface 112. The outer surface 112 of the lower end portion 101 has an exposed surface 112 b exposed from the dense film 122.

  The support substrate 110 of the present embodiment is a flat cylindrical flat plate extending in the longitudinal direction. For this reason, as shown in FIG. 4, the support substrate 110 includes the first major surface 113, the second major surface 114 opposite to the first major surface 113, the first major surface 113, and the second major surface 114. And a pair of side end surfaces 115 connecting the two. The first major surface 113, the second major surface 114, and the pair of side end surfaces 115 constitute the outer surface of the support substrate 110. The first major surface 113 and the second major surface 114 face each other with the gas channel 111 interposed therebetween, and extend in parallel with each other. The distance between the first main surface 113 and the second main surface 114, that is, the thickness of the support substrate 110 is, for example, 1 to 10 mm. The pair of side end surfaces 115 are both ends in the width direction. The first main surface 113 and the second main surface 114 are flat surfaces, and the pair of side end surfaces 115 are curved surfaces.

  The lower end surface 116 is continuous with the lower end of the first main surface 113, the second main surface 114, and the pair of side end surfaces 115. The lower end surface 116 is a surface facing downward. Specifically, the lower end surface 116 is a surface located at the lower end of the support substrate 110 and extending in a direction intersecting with the vertical direction. The upper end surface 117 is continuous with the upper end of the first main surface 113, the second main surface 114, and the pair of side end surfaces 115. The upper end surface 117 is a surface facing upward. The lower end surface 116 located at the lower end and the upper end surface 117 located at the upper end face each other.

  As shown in FIG. 5, the outer surface 112 of the support substrate 110 has a plurality of first recesses 112a. Each first recess 112 a is formed on both surfaces (the first major surface 113 and the second major surface 114) of the support substrate 110. The first recesses 112 a are formed to be spaced apart from each other in the longitudinal direction of the support substrate 110.

  The support substrate 110 is made of a porous material. The porous material has a large number of pores. The porosity of the porous material is, for example, 20% or more and 60% or less, preferably 25% or more and 55% or less. In the present specification, “porosity” is a value measured by digitizing the pore portion by image analysis of a cross-sectional image of FE-SEM. Specifically, the image magnified 7500 times with FE-SEM is analyzed by the image analysis software HALCON made by MVTec. The area occupancy rates of the material portion and the pore portion are obtained on the cross-sectional image after analysis, and the area occupancy rate of the pore portion is defined as the porosity. The cross-sectional image is taken for each of the 10 fields of view to quantify the porosity, and the average value is taken as the porosity.

  The pore size is, for example, 0.3 μm to 10 μm, and preferably 0.5 μm to 5 μm. In the present specification, the "pore diameter" is the value of the circle equivalent diameter of the pore obtained by image analysis of the cross-sectional image of the FE-SEM. Here, the equivalent circle diameter is the diameter of a circle having an area value of a measurement target (particles or pores) obtained by image analysis of a cross section. Similar to the calculation of the porosity, the cross-sectional image is photographed for 10 views to quantify the pore diameter. The average pore diameter of each visual field is calculated, and the average pore diameter of 10 visual fields is further averaged to be defined as the pore diameter.

The porous material is insulating, and is formed of, for example, a ceramic. Specifically, the support substrate 110 may be made of CSZ (calcia stabilized zirconia), NiO (nickel oxide) and YSZ (8YSZ) (yttria stabilized zirconia). may be constituted from NiO and _Y 2 _{O 3} and (yttrium oxide), MgO may be configured from (magnesium oxide) and MgAl ₂ O ₄ and (magnesia alumina spinel).

  At least a part of the exposed surface 112 b and the lower end surface 116 exposed from the dense film 122 on the outer surface 112 forms a dense region 119 impregnated with another material. For this reason, the support substrate 110 has a porous region 118 and a dense region 119. The supporting substrate 110 of the present embodiment mainly includes the porous region 118 formed of the above-described porous material, and the remaining portion is formed of the dense region 119.

In the dense region 119, another material is disposed in at least a part of the pores of the porous material constituting the support substrate 110. The other material is not particularly limited, but it is preferably made of glass, ceramics, etc., for example. As the glass, for example, crystallized glass, amorphous glass, partially crystallized glass partially crystallized can be used, crystallized glass and amorphous glass are preferable, and crystallized glass is more preferable. The crystallized glass, for _example, SiO 2 _-B 2 _{O 3 system,} SiO 2 -CaO-based, or _SiO 2 -MgO system may be employed. In addition, in this specification, the ratio (the degree of crystallinity) of “volume occupied by the crystal phase” to the total volume is 60% or more, and “the volume occupied by the amorphous phase and the impurities to the total volume” Refers to glass with a percentage of less than 40%. In addition, as another material, amorphous glass, a brazing material, or ceramics may be employed. Specifically, the dense region 119 is selected from the group consisting of the SiO ₂ -MgO-B ₂ O ₅ -Al ₂ O ₃ system and the SiO ₂ -MgO-Al ₂ O ₃ -ZnO system in the pores of the porous material. At least one other material is disposed.

  The other material is particularly preferably the same as the first bonding material 300 described later. In this case, the dense region 119 is impregnated with the same material as the first bonding material 300 from at least one of the exposed surface 112 b and the lower end surface 116. That is, in the dense region 119, the same material as the material forming the first bonding material 300 is disposed in at least a part of the pores of the porous material forming the support substrate 110.

  The dense region 119 has a lower porosity than the porous material constituting the support substrate 110, ie, the porous region 118. The porosity of the dense region 119 is, for example, 10% or less, preferably 7% or less. The porosity of the dense region 119 may be 0%.

  The impregnation depth D of the other material from at least a part of the exposed surface 112b and the lower end face 116 (dense film non-formed portion) in the dense region 119 is 1.0 μm or more, preferably 1.5 μm to 1000 μm. is there. The impregnation depth D may or may not be constant at a distance from the impregnation surface. If not constant, the impregnation depth D is the maximum depth.

  Further, the dense region 119 extends inward from at least a portion of the exposed surface 112 b and the lower end surface 116. That is, the dense region 119 extends inward from at least a portion of the outer surface 112 and the lower end surface 116 located in the region R near the lower end surface. As shown in FIG. 6, the depth in the direction (z-axis direction in FIG. 7) orthogonal to the direction (x-axis direction in FIG. 7) in which the dense region 119 extends in the cross section (z-axis direction) of the fuel cell 100 Is the impregnation depth D.

  In the structure shown in FIG. 7, the dense region 119 is impregnated with the other material from the entire exposed surface 112b by 1.0 μm or more. That is, the dense region 119 extends 1.0 μm or more toward the inside from the entire exposed surface 112 b. The dense region 119 is an annular shape having a maximum depth D from the exposed surface 112 b of 1.0 μm or more.

  The impregnation depth D can be adjusted by the particle diameter of the other material disposed in the pores of the porous material, the reduced pressure at the time of the impregnation treatment in which the porous material is impregnated with the other material, and the like. Specifically, the depth D is increased by impregnating a material having a small particle diameter. In addition, the depth D is increased by lowering the pressure inside the porous material at the time of impregnation.

  Further, the position of the dense region 119 can be adjusted by performing the impregnation process in a state where the mask is formed in a region other than the position where the dense region 119 is to be formed.

[Manifold]
As shown in FIGS. 1 to 3, the manifold 200 supplies a reaction gas to the fuel cell 100. The manifold 200 is hollow and has an internal space. As shown in FIG. 1, a fuel gas is supplied to the internal space of the manifold 200 through the inlet pipe P. As shown in FIG. 2, the manifold 200 has a plurality of insertion holes 231 communicating the internal space with the outside.

  The manifold 200 is substantially rectangular. As shown in FIG. 3, the manifold 200 includes a bottom wall 210, a side wall 220, an upper wall 230, and a flange portion 240.

  The bottom wall 210, the side wall 220, and the flange portion 240 are integrally formed. The integrally formed bottom wall 210, the side wall 220 and the flange portion 240, and the top wall 230 are separate members and are joined. The bottom wall 210, the side wall 220, the top wall 230, and the flange portion 240 are made of, for example, a metal having heat resistance.

  The bottom wall 210 has a rectangular shape in plan view (x-axis direction). The side wall 220 extends upward from the outer peripheral portion of the bottom wall 210. The flange portion 240 extends outward from the upper end of the side wall 220. The flange portion 240 is annular.

  The upper wall 230 is configured to close the upper end of the side wall 220. Specifically, the outer peripheral portion of the upper wall 230 is disposed on the flange portion 240. In order to seal the inner space of the manifold 200, the upper wall 230 is joined to the flange portion 240 all around. The upper wall 230 is joined to the flange portion 240 by, for example, a joining material, welding or the like.

  As shown in FIG. 2, the upper wall 230 has a plurality of insertion holes 231 into which the fuel cells 100 are inserted. Each insertion hole 231 extends in the width direction (y-axis direction) of the manifold 200. Further, the insertion holes 231 are spaced apart from each other in the longitudinal direction of the manifold 200.

[First bonding material]
The first bonding material 300 fixes the fuel cell 100 to the manifold 200. Specifically, the first bonding material 300 bonds the lower end portion 101 of the fuel cell 100 and the upper wall 230 of the manifold 200. Specifically, the first bonding material 300 is in contact with the exposed surface 112 b and the dense film 122. The first bonding material 300 may be in contact with only the exposed surface 112 b without contacting the dense film 122. In the state where the fuel cell 100 is fixed to the manifold 200, the insertion hole 231 and the gas flow path 111 are in communication.

  The first bonding material 300 separates the inner space of the manifold 200 (the space exposed to the fuel gas) and the outside of the cell stack device 1 (the space exposed to the gas containing oxygen), thereby forming the fuel gas It has a function to prevent the mixture of oxygen and the gas containing oxygen. For this reason, as shown in FIG. 6, the first bonding material 300 has an exposed surface 301 which is a surface exposed to the fuel gas, and an outer surface 302 exposed to the gas containing oxygen. The exposed surface 301 is exposed to the internal space of the manifold 200. The outer surface 302 is exposed to the outside of the cell stack device 1.

The first bonding material 300 is, for example, crystallized glass. The crystallized glass, for _example, SiO 2 _-B 2 _{O 3 system,} SiO 2 -CaO-based, or _SiO 2 -MgO system may be employed. As a material of the first bonding material 300, amorphous glass, brazing material, or ceramic may be employed. Specifically, the first bonding material 300 is at least one selected from the group consisting of a SiO ₂ -MgO-B ₂ O ₅ -Al ₂ O ₃ system and a SiO ₂ -MgO-Al ₂ O ₃ -ZnO system. .

[Production method]
Subsequently, a method of manufacturing the cell stack device 1 according to the present embodiment will be described with reference to FIGS.

  First, as shown in FIG. 8, a plurality of cell bodies 103 in which the power generation element portion 120 and the dense film 122 are formed on a substrate made of a porous material are prepared. Also, the manifold 200 is prepared. Then, the cell bodies 103 are connected to each other by the materials to be the first current collecting member 4 and the second bonding material 5, and the cell assembly 104 is manufactured. At this stage, the second bonding material 5 is not fired, and the cell bodies 103 are temporarily fixed to each other.

  Next, as shown in FIG. 9, the lower end portion 101 of each cell body 103 of the cell assembly 104 is inserted into each insertion hole 231 of the manifold 200. In addition, you may use the jig for each cell body 103 to hold | maintain a predetermined space | interval along thickness direction.

  Next, as shown in FIG. 2, a material to be the first bonding material 300 is applied so as to bond the cell body 103 inserted into the insertion hole 231 and the upper wall 230 of the manifold 200.

  Further, a material to be the first bonding material 300 is applied to at least a part of the exposed surface 112 b and the lower end surface 116. In addition, the material used as the 1st bonding material 300 is a slurry form.

  In addition, in order to make only a predetermined | prescribed site | part into an impregnation surface, you may form a mask on surfaces other than a predetermined site | part prior to the process of apply | coating the material used as the 1st bonding material 300.

  Next, it is impregnated from the impregnation surface so that the impregnation depth of the material to be the first bonding material 300 is 1.0 μm or more. In this step, the inside of the porous material is depressurized after or before the material to be the first bonding material 300 is applied to the impregnated surface. For example, after removing air from the pores of the porous material by evacuation, the material to be the first bonding material 300 is applied to the impregnated surface.

  Next, heat treatment is applied to the materials to be the first bonding material 300 and the second bonding material 5. By this heat treatment, the first bonding material 300 and the second bonding material 5 are solidified. Specifically, the second bonding material 5 is fired by heat treatment. As a result, each fuel cell 100 and the first current collecting member 4 are fixed. Further, the material to be the first bonding material 300 is subjected to heat treatment so that the temperature of the amorphous material reaches the crystallization temperature. Then, a crystal phase is generated inside the material at the crystallization temperature, and crystallization proceeds. As a result, the amorphous material is solidified and ceramicized to form crystallized glass. As a result, the first bonding material 300 made of crystallized glass exhibits a function, and the lower end portion 101 of each fuel cell 100 is fixed to the upper wall 230 of the manifold 200. Moreover, while the other material comprised with crystallized glass is arrange | positioned to the pore of a porous material, the impregnation area | region D can form the dense area | region 119 of 1.0 micrometer or more.

  By carrying out the above steps, the fuel cell 100 and the cell stack device 1 shown in FIGS. 1 to 7 can be manufactured.

  In the above-described manufacturing method, the case where the material disposed in the pores of the dense region 119, the first bonding material 300, and the coating film 170 are formed of the same material has been described as an example. In the present invention, the material disposed in the pores of the dense region 119, the first bonding material 300, and the covering film 170 may be the same material or different materials.

  Further, in the above manufacturing method, the same material as the first bonding material 300 is applied to the impregnated surface in a reduced pressure atmosphere to form the dense region 119 having an impregnation depth D of 1.0 μm or more as an example. did. The dense region 119 may be formed in the step of preparing the cell body 103 instead of or in combination with the step of vacuuming. In this case, prior to the step of applying the first bonding material 300, a cell body 103 made of a porous material is prepared, and at least a part of the exposed surface 112b and the lower end surface 116 is impregnated with another material.

[Operation]
The operation of the cell stack device 1 according to the present embodiment will be described with reference to FIGS. The cell stack device 1 operates, for example, as follows.

By flowing fuel gas (such as hydrogen gas) into the gas flow path 111 of each fuel cell 100 via the manifold 200 and exposing both surfaces of the support substrate 110 to gas (such as air) containing oxygen, it is possible to The oxygen partial pressure difference generated between the two sides generates an electromotive force. When the cell stack device 1 is connected to an external load, an electrochemical reaction shown in the following equation 1 occurs in the air electrode 150, and an electrochemical reaction shown in the following equation 2 occurs in the fuel electrode 130.
(1/2) O ₂ + 2e ⁻ → O ^{2 −} (Equation 1)
^{_{H 2 + O 2- → H 2}} O + 2e - ··· ( Formula 2)
Further, surplus fuel gas not used for power generation among the fuel gas flowing through the gas flow channel 111 of the support substrate 110 is discharged to the outside from the discharge port located on the other end side of the gas flow channel 111. Then, the surplus fuel gas discharged from the discharge port and the gas containing oxygen are mixed and burned.

[Effect]
Subsequently, the operation of the fuel cell unit 100 and the cell stack device 1 of the present embodiment will be described in comparison with a comparative example shown in FIG. The fuel cell and the cell stack device of the comparative example shown in FIG. 18 are provided with the support substrate 110 which does not have the dense region 119.

  As shown in FIG. 18, when the fuel cell and cell stack device of the comparative example operate, thermal stress due to the temperature distribution of the thermal cycle is generated in the fuel cell and the manifold. This thermal stress generates a bending moment in the region R near the lower end face of the fuel cell as shown by the arrow in FIG. Since the supporting substrate 110 has a bending strength lower than that of the first bonding material 300, cracks are generated preferentially in the region R near the lower end surface of the supporting substrate 110 of the fuel cell. When the crack originating from the region R near the lower end face of the support substrate 110 further grows, the crack C becomes a passage connecting the internal space of the manifold and the external space of the manifold, and the fuel gas introduced into the internal space becomes the internal space Leak to the outside space. For this reason, in the cell stack device of the comparative example, the gas leak can not be sufficiently suppressed.

  On the other hand, the fuel cell 100 and the cell stack device 1 of the present embodiment shown in FIGS. 6 and 7 are the lower end portion 101 joined to the first bonding material 300 and exposed from the dense film 122 at the outer surface 112 And a support substrate 110 having a dense region 119 impregnated with another material by 1.0 μm or more from at least a part of the lower end surface 116. Even if thermal stress is applied to the fuel cell 100 and the manifold 200 when the cell stack device 1 of the present embodiment operates, the strength of the region R near the lower end face of the fuel cell 100 where the dense region 119 is formed is Since the height is high, it is possible to suppress the crack having the region R near the lower end surface of the fuel cell 100 as a base point. For this reason, the fuel cell 100 can suppress a crack that connects the internal space of the manifold 200 and the external space of the manifold 200. Therefore, the cell stack device 1 can suppress the gas leak.

  Further, the dense region 119 of the present embodiment is impregnated with the same material as the material constituting the first bonding material 300 from at least a part of the exposed surface 112 b and the lower end surface 116, and the impregnation depth D is 1. It is 0 μm or more. The penetration of the first bonding material 300 into the pores of the porous material constituting the support substrate 110 provides an anchor effect. The outer surface of the dense film 122 is a smooth surface, but the anchor effect can improve the bonding strength between the fuel cell 100 and the first bonding material 300. Therefore, peeling of the fuel cell 100 and the first bonding material 300 can be suppressed.

Second Embodiment
The fuel cell 105 and the cell stack device 2 of the second embodiment shown in FIGS. 10 to 12 basically have the same configuration as the fuel cell 100 and the cell stack device 1 of the first embodiment. , And in the shape of the dense region 119.

[Coating film]
As shown in FIGS. 10 and 11, a covering film 170 is formed to cover at least a part of the lower end surface 116 of the support substrate 110.

  The coating film 170 is formed of a material having a bending strength higher than that of the porous material forming the support substrate 110. The ratio of the bending strength of the covering film 170 to the bending strength of the porous region 118 of the support substrate 110 (the bending strength of the covering film 170 / the bending strength of the porous region 118) is preferably 1.1 or more. More preferably, it is 1 or more and 20 or less. The bending strength of the lower end part of the fuel cell 105 can be effectively improved as it is 1.1 or more.

  Here, "bending strength" is a value measured based on the room temperature four-point bending strength test method of fine ceramics specified in JIS R1601.

The coating film 170 is a dense film. The material constituting the coating film 170 is made of, for example, glass, ceramics or the like, and is preferably made of glass. For example, crystallized glass can be used as the glass. The crystallized glass, for _example, SiO 2 _-B 2 _{O 3 system,} SiO 2 -CaO-based, or _SiO 2 -MgO system may be employed. In addition, as a material of the coating film 170, amorphous glass, a brazing material, ceramics, etc. may be employ | adopted. Specifically, the coating film 170 is at least one selected from the group consisting of a SiO ₂ -MgO-B ₂ O ₅ -Al ₂ O ₃ system and a SiO ₂ -MgO-Al ₂ O ₃ -ZnO system.

  The material forming the covering film 170 may be the same as or different from the material forming the first bonding material 300. In the former case, the covering film 170 may be continuous with the first bonding material 300 or may be separated from the first bonding material 300.

  The coating film 170 covers at least a part of the lower end surface 116 of the support substrate 110, and in the present embodiment, covers the entire periphery of the outer peripheral portion of the lower end surface 116. The coating film 170 may cover the entire lower end surface 116. In addition, as shown in FIG. 11, the covering film 170 covers the entire lower end surface 116 in a cross-sectional view in the width direction (z-axis direction) including the gas flow path 111.

  The thickness of the covering film 170 may or may not be constant as shown in FIG. The maximum thickness of the coating film 170 is, for example, 10 μm to 1000 μm.

[Dense area]
As shown in FIG. 12, the dense region 119 has a first region 119a impregnated with another material from the exposed surface 112b and a second region 119b impregnated with another material from the lower end surface 116. ing. The impregnation depth of the dense region 119 means the maximum depth of the impregnation depth D1 from the exposed surface 112b and the impregnation depth D2 from the lower end surface 116. Specifically, among the impregnation depth D1 of the first region 119a and the impregnation depth D2 of the second region 119b, the maximum depth is 1.0 μm or more, preferably 1.5 μm to 1000 μm. That is, the dense region 119 is provided from at least a part of the exposed surface 112 b or the lower end surface 116 over an impregnation depth of 1.0 μm.

  The impregnation depth D1 of the first region 119a is orthogonal to the direction in which the first region 119a extends (the x-axis direction in FIG. 11) in the cross section (z-axis direction) of the fuel cell 105 (FIG. 11). maximum depth in the z-axis direction). The impregnation depth D2 of the second region 119b is orthogonal to the direction in which the second region 119b extends (z-axis direction in FIG. 12) in the cross section (z-axis direction) of the fuel cell 105 as shown in FIG. Maximum depth in the direction (x-axis direction in FIG. 11). The impregnation depth in the present embodiment is the depth in the direction orthogonal to the impregnation surface, and in detail, the impregnation depth D1 of the first region 119a is the depth in the direction orthogonal to the exposed surface 112b, The impregnation depth D2 of the second region 119b is a depth in a direction orthogonal to the lower end surface 116.

  The first region 119a extends inward from the exposed surface 112b by a predetermined depth D1 and is annular. Each of the second regions 119 b extending inward from the impregnated surface in the lower end surface 116 is in a downwardly concave shape, that is, in a downward arc shape.

  The porosity of the first region 119a and the second region 119b may be the same or different. For example, the overlapping region of the first region 119a and the second region 119b has a higher porosity than the other regions.

[First bonding material]
The first bonding material 300 is in contact with the dense film 122 and the exposed surface 112 b of the fuel cell 105 and the upper wall 230 of the manifold 200. The first bonding material 300 may be in contact with only the exposed surface 112 b without contacting the dense film 122. In addition, the first bonding material 300 may further contact the coating film 170.

  The coating film 170 of the support substrate 110 and the first bonding material 300 are the same material and are continuous. In FIGS. 10 and 11, the lower end surface 171 of the coating film 170 and the exposed surface 301 of the first bonding material 300 are at the same position in the vertical direction. That is, the exposed surface 301 and the lower end surface 171 are located on the same plane. In addition, in FIG. 6, although the exposed surface 301 and the lower end surface 171 are typically shown as a plane, an unevenness | corrugation is formed in fact.

[Production method]
The method of manufacturing the fuel cell 105 and the cell stack device 2 of the second embodiment basically has the same configuration as that of the first embodiment, but further includes the step of forming the coating film 170. The difference is in the process of forming a dense area 119 having a dot and a second area 119b.

  Specifically, a material to be the first bonding material 300 is applied to at least a part of the exposed surface 112 b of each cell body 103. Further, a material to be the first bonding material 300 is applied to at least a part of the lower end surface 116 of each cell body 103. The material to be applied to the lower end face 116 is disposed in the pores of the porous material and becomes the covering film 170.

  Next, the material to be the first bonding material 300 is impregnated from the impregnation surface so that the impregnation depth is 1.0 μm or more.

  Next, heat treatment is applied to the materials to be the first bonding material 300 and the second bonding material 5. By this heat treatment, the first bonding material 300 and the second bonding material 5 are solidified. Thereby, the dense region 119 having the first region 119a and the second region 119b in which the same material as the first bonding material 300 is disposed in the pores of the porous material can be formed. In addition, a coating film 170 made of crystallized glass is formed to cover at least a part of the lower end surface 116 of each support substrate 110.

  In addition, in the said manufacturing method, the case where the 1st bonding material 300 and the coating film 170 were integrally formed with the same material was mentioned as the example, and was demonstrated. Then, although the step of forming the first bonding material 300 and the step of forming the covering film 170 are performed simultaneously with the above-described manufacturing method, the steps may not be performed simultaneously. For example, after the covering film 170 is formed on the lower end surface 116 of the support substrate 110, the fuel cell 105 and the manifold 200 may be bonded by the first bonding material 300. Also, for example, after a material to be the covering film 170 is applied to the lower end surface 116 of the support substrate 110, a material to be the first bonding material 300 is applied to bond the cell body 103 and the manifold 200, and then heat treatment is performed. May be applied simultaneously.

  Further, the case where the material disposed in the pores of the dense region 119, the first bonding material 300, and the covering film 170 are formed of the same material has been described as an example. The material to be disposed in the pores of the dense region 119, the first bonding material 300, and the covering film 170 may be the same material or different materials.

[Effect]
The fuel cell 105 and the cell stack device 2 of the present embodiment shown in FIGS. 10 to 12 cover at least a part of the lower end face 116 and have higher bending strength than the material forming the porous region 118 of the support substrate 110. It further comprises a covering film 170 formed of a material. Even if thermal stress is applied to the fuel cell 105 and the manifold 200 when the cell stack device 2 of the second embodiment operates, the bending strength of the lower end of the fuel cell 105 with the covering film 170 formed is high. The crack originating from the lower end of the fuel cell 105 can be suppressed. In addition to the crack suppression due to the improvement of the strength of the region R near the lower end surface by the dense region 119 of the support substrate 110, the fuel cell 105 further includes the crack connecting the internal space of the manifold 200 and the external space of the manifold 200. It can be suppressed. Therefore, the cell stack device 2 can further suppress the gas leak.

Third Embodiment
The fuel cell and cell stack device 2a of the second embodiment shown in FIG. 13 basically has the same configuration as the fuel cell and cell stack device 2 of the second embodiment shown in FIG. The dense region 119 of the third embodiment is different in that it is impregnated with a plurality of other materials and in the material constituting the covering film 170.

Specifically, the material forming the covering film 170 is different from the material forming the first bonding material 300. The material constituting the first bonding material 300 is, for example, crystallized glass, and the material constituting the coating film 170 is, for example, YSZ (yttria stabilized zirconia), CSZ (calcia stabilized zirconia), NiO (oxidized) Nickel) and YSZ (8 YSZ) (yttria stabilized zirconia), NiO (nickel oxide) and Y ₂ O ₃ (yttrium oxide), MgO (magnesia) and MgAl ₂ O ₄ (magnesia alumina spinel), MgO (magnesia) and Y It is a composite material of ₂ O ₃ (yttrium oxide).

  The coating film 170 has a first film formed of the above material and a second film formed under at least a part of the first film, and the second film is The same material as the first bonding material 300 may be used. However, in the second and third embodiments, the exposed surface 301 of the first bonding material 300 and the lower end surface 171 of the covering film 170 are at the same position in the vertical direction. That is, the exposed surface 301 and the lower end surface 171 are located on the same plane. Since FIGS. 10 and 13 schematically show the coating film 170 and the first bonding material 300, the exposed surface 301 and the lower end surface 171 are schematically shown as a plane, In fact, unevenness is formed. The same applies to FIGS. 14 to 17 schematically showing the covering film 170 and the first bonding material 300 in the fuel cells and the cell stack devices of the fourth to seventh embodiments described later.

  In addition, the dense region 119 has a first region 119a impregnated with another material from the exposed surface 112b and a second region 119b impregnated with another material from the lower end surface 116. In the present embodiment, the first region 119a is impregnated with the same material as the first bonding material 300 from the exposed surface 112b. The second region 119 b is impregnated with the material constituting the coating film 170 from the lower end surface 116.

Embodiment 4
The fuel cell and cell stack device 2b of the fourth embodiment shown in FIG. 14 basically have the same configuration as the fuel cell and cell stack device 2 of the second embodiment shown in FIG. The lower end surface 171 of the coating film 170 of the fourth embodiment is different in that it is located below the exposed surface 301 of the first bonding material 300.

  Specifically, the exposed surface 301 of the first bonding material 300 is at the same position as the lower end surface 116 of the support substrate 110 in the vertical direction. The fuel cell unit of the third embodiment extends downward from the exposed surface 301 of the first bonding material 300 by the thickness of the covering film 170 formed on the lower end surface 116.

Fifth Embodiment
The fuel cell and cell stack device 2c of the fifth embodiment shown in FIG. 15 basically have the same configuration as the fuel cell and cell stack device 2 of the second embodiment shown in FIG. The lower end surface 116 of the support substrate 110 of the fifth embodiment includes a C surface 116 a and is different in that a covering film 170 is formed under the C surface 116 a.

  Specifically, the lower end surface 116 of the support substrate 110 is composed of a horizontal surface 116 b extending in the horizontal direction, and a C surface 116 a connected to the horizontal surface 116 b. The horizontal surface 116 b extends from the edge forming the gas channel 111 to the outer surface 112 side. The C surface 116 a is formed by C-chamfering a corner portion continuous with the outer surface 112. In addition, "C surface" is the surface which chamfered the ridgeline which a surface and a surface make in planar shape.

  The lower end surface 171 of the covering film 170 formed under the C surface 116 a is at the same position as the exposed surface 301 of the first bonding material 300 in the vertical direction. Therefore, the thickness of the covering film 170 increases in a tapered manner toward the outer surface 112.

  The covering film 170 may further cover at least a part of the horizontal surface 116 b. Further, the lower end surface of the support substrate of the present invention may include an R surface instead of the C surface. The “R-surface” is a surface (arc surface) obtained by chamfering a ridge line formed by a surface and a surface into an arc shape convex outward or inward.

  The dense region 119 in the present embodiment has a first region 119a formed by impregnating another material from the exposed surface 112b and a second region 119b formed by impregnating another material from the C surface 116a. . The second region 119 b has a shape in which a central portion is recessed along the C surface 116 a.

Sixth Embodiment
The fuel cell and cell stack device 2d of the sixth embodiment shown in FIG. 16 basically have the same configuration as the fuel cell and cell stack device 2 of the second embodiment, but the sixth embodiment The lower end surface 171 of the support substrate 110 is different in that it is curved upward. That is, the lower end surface 171 has an upward arc shape.

  A covering film 170 is formed under the curved lower end face 116. The lower end surface 171 of the covering film 170 is at the same position as the exposed surface 301 of the first bonding material 300 in the vertical direction. For this reason, the thickness of the covering film 170 increases from the corner to the center.

Seventh Embodiment
The fuel cell and cell stack device 2e of the seventh embodiment shown in FIG. 17 basically has the same configuration as the fuel cell and cell stack device 2 of the second embodiment, but the seventh embodiment The lower end surface 171 of the support substrate 110 differs in that it is curved downward. That is, the lower end surface 171 has a downward arc shape.

  A covering film 170 is formed under the curved lower end face 116. The lower end surface 171 of the covering film 170 is at the same position as the exposed surface 301 of the first bonding material 300 in the vertical direction. For this reason, the thickness of the covering film 170 decreases from the corner to the center.

  The fuel cells and cell stack devices 2d and 2e of the sixth and seventh embodiments have a manufacturing advantage in that the coating film 170 of the same material as the first bonding material 300 can be easily formed on the lower end surface 116 of the support substrate 110. have.

  Further, in the sixth and seventh embodiments, as in the second embodiment, the support substrate 110 is a dense region in which at least a portion of the exposed surface 112 b and the lower end surface 116 is impregnated with another material by 1.0 μm or more. It has 119.

(Modification)
Here, the cell stack device according to the first to seventh embodiments described above has been described by taking the horizontal stripe type in which the plurality of power generation element units 120 are disposed on one main surface of the support substrate 110 as an example. The cell stack device may be of a vertically-striped type in which one power generation element is disposed on one main surface of the support substrate. Moreover, although the cell stack apparatus of Embodiment 1-6 is provided with the cylindrical flat type support substrate 110, the cell stack apparatus of this invention may be provided with the cylindrical support substrate.

  The fuel cells of Embodiments 1 to 7 have been described by taking the structure including the insulating support substrate 110 as an example, but the support substrate of the present invention may be insulating or conductive. It may be.

  Further, in the first to seventh embodiments, the lower end portion of one fuel cell is inserted into one insertion hole 231 formed in the manifold 200, but in the present invention, a plurality of fuel cells are inserted into one insertion hole. Cells may be inserted.

  Moreover, although the manifold 200 of Embodiment 1-7 is a structure where the upper surface of the side wall 220 is open and the upper wall 230 obstruct | occludes the upper surface, the manifold of this invention is not limited to this. For example, the side wall and the upper wall may be integrated, and the lower end surface of the side wall may be open, and the lower end surface may be closed by the bottom wall.

  Further, in the manifold 200 of Embodiments 1 to 7, the side wall 220 extends upward substantially perpendicularly from the bottom wall 210, but the manifold of the present invention is not limited to this. For example, the side wall 220 may be sloped so as to extend outwardly upward, and may be inclined so as to outwardly flare downward.

  In this example, the effect of having a dense region in which another material is impregnated by 1.0 μm or more was examined from at least a part of the exposed surface and the lower end surface of the support substrate of the porous material.

(Examples 1, 2, 5 to 7)
The cell stack devices of Examples 1, 2, 5 to 7 were manufactured according to the manufacturing method of Embodiment 1 described above. Specifically, a material to be the support substrate 110 made of a porous material having a porosity of 40% was prepared. The power generation element portion 120 and the dense film 122 were formed on this material, and the plurality of cell bodies 103 were joined to one another to produce a cell assembly 104. The dense film 122 was formed such that the outer surface connected to the lower end face 116 was exposed by 500 μm. The cell body 103 was inserted into the insertion hole 231 of the manifold 200, and slurry-like glass was applied as a material to be the first bonding material 300 so as to bond the exposed surface of the cell body 103 and the upper wall 230 of the manifold 200. Next, vacuum drawing was performed, and the same glass as the material to be the first bonding material was applied on the exposed surface 1112 b exposed from the dense film 122, and the glass was impregnated from the exposed surface 112 b. Next, heat treatment was performed to form a first bonding material 300 made of crystallized glass, and a dense region 119 in which the crystallized glass was disposed in the pores of the porous material was formed. The impregnation depth D from the exposed surface 112b is described in Table 1 below.

(Examples 3 and 4)
The cell stack devices of Examples 3 and 4 are different from those of Examples 1 and 2 in that they have a dense region in which a material different from the material of the first bonding material 300 is impregnated.

  Specifically, the same material as the supporting substrate 110 as in Examples 1, 2 and 5 to 7 was prepared, and amorphous glass was impregnated from the exposed surface 112 b. Similar to Examples 1, 2 and 5 to 7, slurry-like glass was applied as a material to be the first bonding material 300, and heat treatment was performed. As a result, the first bonding material 300 made of crystallized glass is formed, and the dense region 119 in which the amorphous glass is disposed in the pores of the porous material is formed. The impregnation depth D from the exposed surface 112b is described in Table 1 below.

(Comparative example 1)
The cell stack device of Comparative Example 1 was different from Examples 1 to 7 in that the supporting substrate was not impregnated with another material. That is, the supporting substrate of Comparative Example 1 was only the porous region 118 and did not have the dense region 119.

(Comparative example 2)
The cell stack device of Comparative Example 2 was different from Examples 1, 2 and 5 to 7 in that a compact region with a small impregnation depth from the exposed surface was formed by shortening the vacuuming time.

(Comparative example 3)
The cell stack device of Comparative Example 3 was different from Examples 3 and 4 in that a dense region with a small impregnation depth from the exposed surface was formed by increasing the particle diameter of the other material to be impregnated.

(Evaluation method)
With respect to the cell stack devices of Examples 1 to 7 and Comparative Examples 1 to 3, the strength and bonding strength of the fuel cells were examined by a thermal cycle test. Specifically, each cell stack device is installed in an electric furnace, and after raising and lowering the temperature rising / falling speed 400 ° C./hr 10 times from room temperature to 800 ° C. repeatedly, it is taken out from the electric furnace and cracked in the fuel cell The presence or absence of occurrence, the amount of gas leak, and the presence or absence of a crack occurrence in the bonding material were examined. The results are listed in Table 1 below.

  In Table 1 below, with respect to the strength of the fuel cell, a penetrant was applied to the lower end face of the fuel cell, and the presence or absence of cracks was confirmed by observation with a microscope. In addition, after sealing the outlet end of the gas flow path 111 of the fuel cell 100, argon gas is supplied from the introduction pipe P of the manifold 200, and the inside of the manifold 200 is maintained at an applied pressure of 20 kPa. Was measured. In Table 1, "◎" means no cracks and no gas leak, "○" means fine cracks but no gas leak, "×" has cracks, It means that there was a gas leak.

  Regarding the bonding strength, a penetrant was applied to the lower end surface of the first bonding material, and the presence or absence of a crack was confirmed by observing with a microscope. The results are set forth in Table 1 below. In Table 1, "◎" means that there was no crack, "○" means that there was a minute crack, and "×" means that there was a crack.

(Evaluation results)
As shown in Table 1, Examples 1 to 7 in which the impregnation depth D from the exposed surface 112b was 1.0 μm or more were able to improve the strength of the fuel cell. In addition, in Examples 2 and 4 in which the impregnation depth D from the exposed surface 112b is 1.5 μm to 1000 μm, the strength of the fuel cell can be further improved.

  Moreover, Example 1, 2, 5-7 which impregnated the same material as the material which comprises a 1st joining material from an exposed surface improves joint strength compared with Example 3 and 4 in which a different material was impregnated. did it.

  On the other hand, in Comparative Example 1 having no dense region, the strength in the region near the lower end face of the fuel cell was very low. Further, in Comparative Examples 2 and 3 in which the impregnation depth was small although the dense region was present, the improvement in strength was insufficient.

  As described above, according to the present embodiment, the fuel cell 100 has a dense region in which at least a portion of the exposed surface 112b of the porous substrate supporting substrate is impregnated with another material by 1.0 μm or more. It has been confirmed that the strength can be improved. Moreover, it has been confirmed that the bonding strength is further enhanced by using the same material as the material to be impregnated into the support substrate and the first bonding material.

  The present inventor has found that even if the impregnation depth D exceeds 1000 μm, the strength of the fuel cell hardly improves. For this reason, the preferable upper limit of the impregnation depth D is 1000 μm from the viewpoint of easily impregnating glass, the viewpoint of reducing the glass material to be impregnated, and the like.

  Further, the strength of the fuel cell 100 can be made similar to that of the fuel cell 100 by having a dense region 119 impregnated with another material of 1.0 μm or more from at least a part of the lower end face 116 instead of or together with the exposed surface 112 b. The present inventors have obtained the finding that it can be improved. Further, the inventor has obtained the knowledge that, by improving the strength of the lower end surface vicinity region R, a crack originating from the lower end surface vicinity region R of the support substrate 110 can be suppressed even if thermal stress is applied. .

  As described above, the present inventor is characterized in that the gas leak can be suppressed by suppressing the cracks by enhancing the strength of the region R near the lower end face, which is a portion where the cracks of the fuel cell tend to occur due to thermal stress I found the effect of Subsequently, the inventor examined the porosity of the supporting substrate at which this effect can be remarkably exhibited. Specifically, the fuel cell was manufactured by variously changing the porosity of the support substrate as follows.

(Examples 8 to 11)
Each of the cell stack devices of Examples 8 to 11 was prepared in that the material to be the support substrate 110 made of the porous material having the porosity of 15%, 20%, 60% and 70% was prepared. It was different from Example 1.

  In Example 8 in which the porosity is less than 20%, it was difficult for the glass to be impregnated from the exposed surface 112b. Further, since the strength of the support substrate 110 itself is high, the effect of the dense region is small.

  In addition, in Example 11 in which the porosity exceeds 60%, the glass is easily impregnated from the exposed surface 112 b. However, since the strength of the support substrate 110 itself is low, the bonding portion with the first bonding material 300 is easily peeled off, and there are micro cracks.

  On the other hand, in Examples 1, 9 and 10 in which the material to be the support substrate 110 made of the porous material having the porosity of 20% or more and 60% or less was prepared, the effect by the dense region was largely exhibited. The strength could be improved. In addition, since it was easy to impregnate the glass from the exposed surface 112b, it was possible to easily form a dense region with an impregnation depth of 1 μm or more. Furthermore, no crack occurred in the joint portion with the first bonding material 300.

  From the above, it has been confirmed that the use of a support substrate made of a porous material having a porosity of 20% or more and 60% or less can significantly improve the bonding strength while the effect of the dense region is remarkable.

  Although the embodiments, modifications and examples of the present invention have been described above, it is also originally intended from the beginning to appropriately combine the features of the embodiments, modifications and examples. In addition, it should be understood that the embodiments, modifications, and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is indicated not by the embodiments, modifications and examples described above but by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims. Ru.

  1, 2, 2a, 2b, 2c, 2d, 2e cell stack device, 4 first current collecting member, 5 second bonding material, 6 second current collecting member, 100, 105 fuel cells, 101 lower end, 102 upper end Part, 103 cell body, 104 cell assembly, 110 support substrate, 111 gas flow path, 112, 302 outer surface, 112a first recess, 113 first main surface, 114 second main surface, 115 side end surface, 116 lower end surface , 116a C plane, 116b horizontal surface, 117 upper end surface, 119 dense region, 120 power generation element portion, 121 reaction preventing film, 122 dense film, 130 fuel electrode, 131 fuel electrode current collector portion, 131a second concave portion, 131b third concave portion , 132 fuel electrode active part, 140 electrolyte, 150 air electrode, 160 electrical connection part, 161 interconnector, 162 air electrode collecting film, 170 subject Coating, 171 lower end surface, 200 manifold, 210 bottom wall, 220 side wall, 230 upper wall, 231 insertion hole, 240 flange portion, 300 first bonding material, 301 exposed surface, C crack, D, D1, D2 depth, L Distance, P Introductory piping, R Lower end surface area.

Claims (5)

A fuel cell whose lower end is supported by a manifold, comprising:
A support substrate comprising a porous material and having an outer surface extending in the vertical direction, and a lower end surface connected to the lower end of the outer surface;
A power generation element portion provided on the outer surface and having a fuel electrode, an electrolyte, and an air electrode;
A dense membrane provided in the lower end portion of the fuel cell so that a part of the outer surface connected to the lower end face is exposed;
Equipped with
The fuel cell according to claim 1, wherein the supporting substrate has an exposed surface exposed from the dense film on the outer surface, and a dense region impregnated with another material by 1.0 μm or more from at least a part of the lower end surface.   The fuel cell according to claim 1, wherein the other material is glass.   The fuel cell according to claim 1, wherein the porosity of the porous material forming the support substrate is 20% or more and 60% or less. The fuel cell according to any one of claims 1 to 3;
A manifold supporting the lower end of the fuel cell;
A bonding material for bonding the manifold and the fuel cell;
A cell stack device comprising:   The cell stack device according to claim 4, wherein the dense region is impregnated with the same material as the material forming the bonding material.

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