JP6335267B2 - Fuel cell stack - Google Patents

Description

  The present invention relates to a fuel cell stack.

  The fuel cell stack includes a manifold and a plurality of fuel cells extending from the manifold (Patent Document 1). Specifically, the manifold has a plurality of insertion holes, and each fuel cell is inserted into the insertion hole. Each fuel cell is electrically connected to each other through a current collecting member. The current collecting member is joined to each fuel cell through a joining material. The current collecting member and the bonding material are collectively referred to as a current collecting joint.

Japanese Patent No. 5551803

  However, the output performance varies depending on the fuel cell stack, and there is a problem in long-term reliability. As a result of intensive studies by the present inventors on this cause, there has been a problem that the reliability of the current collecting junction for performing electrical connection between cells is low. The present application provides a fuel cell stack that improves the reliability of current collecting junctions.

  The fuel cell stack according to the first aspect of the present invention includes a pair of fuel cells, a current collecting member, and a pair of bonding materials. The pair of fuel cells face each other. The current collecting member is disposed between the fuel cells. The current collecting member electrically connects the fuel cells. Each joining material is electroconductive, and joins a current collection member and each fuel cell. The pair of bonding materials includes a first bonding material and a second bonding material that is thicker than the first bonding material.

According to this configuration, the reliability of the current collecting joint can be improved. Specifically, in the conventional fuel cell stack, the thickness of the first bonding material and the thickness of the second bonding material are substantially the same. However, the inventor has found that such a configuration may reduce the reliability of the current collecting joint. That is, the fuel cell may be warped when exposed to a high temperature by a firing process or the like. Due to the warpage of the fuel cell, the distance between the current collecting member and one fuel cell increases, and the distance between the current collecting member and the other fuel cell decreases. For this reason, when the thickness of the 1st joining material and the thickness of the 2nd joining material are the same like the conventional fuel cell stack, there is a possibility that each joining material cannot fully join a current collection member and a fuel cell. There is.

  On the other hand, in the fuel cell stack according to the present invention, the thickness of the first bonding material is different from the thickness of the second bonding material. Specifically, the second bonding material is thicker than the first bonding material. For this reason, even if the distance between the current collecting member and the fuel cell increases due to warpage of the fuel cell, the current collecting member is joined by joining the current collecting member and the fuel cell with the second bonding material. And the fuel battery cell can be sufficiently joined. As a result, the reliability of the current collecting joint can be improved.

  The fuel cell stack according to the second aspect of the present invention includes a fuel cell, a separator, a current collecting member, and a pair of joining materials. The separator is disposed so as to face the fuel battery cell. The current collecting member is disposed between the fuel battery cell and the separator. The current collecting member electrically connects the fuel battery cell and the separator. Of the pair of bonding materials, one bonding material connects the current collecting member and the fuel cell. The other bonding material connects the current collecting member and the separator. The pair of bonding materials includes a first bonding material and a second bonding material that is thicker than the first bonding material.

  Preferably, the first and second bonding materials are formed of conductive ceramics (perovskite type, spinel type, etc.).

  Preferably, the current collecting member has a block shape.

  Preferably, the current collecting member is formed of a fired body of oxide ceramics.

  Preferably, the fuel cell stack further includes a manifold that supplies gas to each fuel cell. Each fuel cell extends upward from the top plate of the manifold.

  According to the present invention, the reliability of the current collecting joint can be improved.

The perspective view of a fuel cell stack. Sectional drawing of a fuel cell stack. The perspective view of a fuel manifold. The perspective view of a fuel cell. Sectional drawing of a fuel cell. Sectional drawing of a fuel cell. Sectional drawing which shows a current collection member and the 1st and 2nd joining material. The figure which shows the junction part of a fuel cell and a fuel manifold. The figure which shows the gas supply method to a fuel cell stack. The figure which shows the manufacturing method of a fuel cell stack. The figure which shows the manufacturing method of a fuel cell stack. Sectional drawing of the fuel cell stack which concerns on a modification. Sectional drawing of the fuel cell stack which concerns on a modification. Sectional drawing of the fuel cell stack which concerns on a modification. Sectional drawing of the fuel cell stack which concerns on a modification. The expanded sectional view of the fuel cell stack concerning a modification. The expanded sectional view of the fuel cell stack concerning a modification.

  Hereinafter, an embodiment of a fuel cell stack according to the present invention will be described with reference to the drawings.

[Fuel cell stack]
As shown in FIGS. 1 and 2, the fuel cell stack 100 includes a manifold 200, a plurality of fuel cells 301, and a plurality of current collecting members 302. The fuel cell 301 is configured as a solid oxide fuel cell.

[Manifold]
As shown in FIG. 3, the manifold 200 is configured to supply fuel gas to each fuel cell 301. The manifold 200 is hollow and has an internal space. Fuel gas is supplied to the internal space of the manifold 200 through the introduction pipe 201. The manifold 200 has a plurality of through-holes 202 arranged along the thickness direction (z-axis direction) of the fuel cell 301. In the present embodiment, the longitudinal direction of the manifold 200 extends along the thickness direction of the fuel cell 301. Each through hole 202 is formed in the top plate 203 of the manifold 200. Each through hole 202 communicates the internal space of the manifold 200 with the outside.

[Fuel battery cell]
As shown in FIG. 2, each fuel cell 301 extends from the manifold 200. Specifically, each fuel cell 301 extends upward (in the x-axis direction) from the top plate 203 of the manifold 200. That is, the longitudinal direction of each fuel cell 301 extends upward. The fuel cells 301 are arranged at intervals from each other in the thickness direction (z-axis direction). That is, each fuel cell 301 is disposed so as to face each other in the thickness direction.

  As shown in FIG. 4, the fuel battery cell 301 includes a plurality of power generation element units 10 and a support substrate 20. Each power generating element unit 10 is supported on both surfaces of the support substrate 20. Each power generation element unit 10 may be supported only on one side of the support substrate 20. The power generation element units 10 are arranged at intervals in the longitudinal direction of the fuel cell 301. That is, the fuel cell 301 according to the present embodiment is a so-called horizontal stripe fuel cell. The power generating element units 10 are electrically connected to each other by an electrical connection unit 30 (see FIG. 5).

  The support substrate 20 has a plurality of gas passages 21 extending in the longitudinal direction of the support substrate 20 inside. Each gas channel 21 extends substantially parallel to each other. As shown in FIG. 5, the support substrate 20 has a plurality of first recesses 22. Each first recess 22 is formed on both surfaces of the support substrate 20. The first recesses 22 are arranged at intervals in the longitudinal direction of the support substrate 20. Each first recess 22 is not formed at both ends of the support substrate 20 in the width direction (y-axis direction).

The support substrate 20 is made of a porous material that does not have electronic conductivity. The support substrate 20 can be made of, for example, CSZ (calcia stabilized zirconia). Alternatively, the support substrate 20 may be composed of NiO (nickel oxide) and YSZ (8YSZ) (yttria-stabilized zirconia), or composed of NiO (nickel oxide) and Y ₂ O ₃ (yttria). Alternatively, MgO (magnesium oxide) and MgAl ₂ O ₄ (magnesia alumina spinel) may be used. The porosity of the support substrate 20 is, for example, about 20 to 60%.

  Each power generation element unit 10 includes a fuel electrode 4, an electrolyte 5, and an air electrode 6. Each power generation element unit 10 further includes a reaction preventing film 7. The fuel electrode 4 is a fired body made of a porous material having electron conductivity. The fuel electrode 4 includes a fuel electrode current collector 41 and a fuel electrode active part 42.

  The fuel electrode current collector 41 is disposed in the first recess 22. Specifically, the fuel electrode current collector 41 is filled in the first recess 22 and has the same outer shape as the first recess 22. Each fuel electrode current collector 41 has a second recess 41a and a third recess 41b. The anode active part 42 is disposed in the second recess 41a. Specifically, the fuel electrode active part 42 is filled in the second recess 41a.

The fuel electrode current collector 41 can be composed of, for example, NiO (nickel oxide) and YSZ (8YSZ) (yttria stabilized zirconia). Alternatively, the fuel electrode current collector 41 may be composed of NiO (nickel oxide) and Y ₂ O ₃ (yttria), or composed of NiO (nickel oxide) and CSZ (calcia stabilized zirconia). Also good. The thickness of the fuel electrode current collector 41 and the depth of the first recess 22 are about 50 to 500 μm.

  The fuel electrode active part 42 may be composed of, for example, NiO (nickel oxide) and YSZ (8YSZ) (yttria stabilized zirconia). Alternatively, the fuel electrode active part 42 may be composed of NiO (nickel oxide) and GDC (gadolinium-doped ceria). The thickness of the fuel electrode active part 42 is 5 to 30 μm.

  The electrolyte 5 is disposed so as to cover the fuel electrode 4. Specifically, the electrolyte 5 extends in the longitudinal direction from one interconnector 31 to another interconnector 31. That is, the electrolyte 5 and the interconnector 31 are alternately arranged in the longitudinal direction of the fuel battery cell 301.

  The electrolyte 5 is a fired body made of a dense material having ionic conductivity and no electronic conductivity. The electrolyte 5 can be made of, for example, YSZ (8YSZ) (yttria stabilized zirconia). Or the electrolyte 5 may be comprised from LSGM (lanthanum gallate). The thickness of the electrolyte 5 is, for example, about 3 to 50 μm.

The reaction preventing film 7 is a fired body made of a dense material and has substantially the same shape as the fuel electrode active portion 42 in a plan view. The reaction preventing film 7 is disposed at a position corresponding to the fuel electrode active part 42 through the electrolyte 5. The reaction preventing film 7 suppresses occurrence of a phenomenon in which YSZ in the electrolyte 5 and Sr in the air electrode 6 react to form a reaction layer having a large electric resistance at the interface between the electrolyte 5 and the air electrode 6. Is provided. The reaction preventing film 7 is, for example, GDC = (Ce, Gd)
It can be composed of O ₂ (gadolinium-doped ceria). The thickness of the reaction preventing film 7 is, for example, about 3 to 50 μm.

The air electrode 6 is disposed on the reaction preventing film 7. The air electrode 6 is a fired body made of a porous material having electron conductivity. The air electrode 6 can be made of, for example, LSCF = (La, Sr) (Co, Fe) O ₃ (lanthanum strontium cobalt ferrite). Alternatively, the air electrode 6 has LSF = (La, Sr) FeO ₃ (lanthanum strontium ferrite), LNF = La (Ni, Fe) O ₃ (lanthanum nickel ferrite), or LSC = (La, Sr) CoO ₃ ( Lanthanum strontium cobaltite) or the like. The air electrode 6 may be composed of 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 6 is, for example, 10 to 100 μm.

The electrical connection unit 30 is configured to electrically connect adjacent power generation element units 10. The electrical connection unit 30 includes an interconnector 31 and an air electrode current collector film 32. The interconnector 31 is disposed in the third recess 41b. Specifically, the interconnector 31 is embedded (filled) in the third recess 41b. The interconnector 31 is a fired body made of a dense material having electronic conductivity. The interconnector 31 can be made of, for example, LaCrO ₃ (lanthanum chromite). Alternatively, the interconnector 31 may be made of (Sr, La) TiO ₃ (strontium titanate). The thickness of the interconnector 31 is, for example, 10 to 100 μm.

  The air electrode current collector film 32 is disposed so as to extend between the interconnector 31 and the air electrode 6 of the adjacent power generation element units 10. For example, the air electrode current collector is configured to electrically connect the air electrode 6 of the power generation element unit 10 disposed on the left side of FIG. 5 and the interconnector 31 of the power generation element unit 10 disposed on the right side of FIG. A membrane 32 is disposed. The air electrode current collector film 32 is a fired body made of a porous material having electron conductivity.

The air electrode current collector film 32 can be made of, for example, LSCF = (La, Sr) (Co, Fe) O ₃ (lanthanum strontium cobalt ferrite). Alternatively, the air electrode current collector film 32 may be made of LSC = (La, Sr) CoO ₃ (lanthanum strontium cobaltite). Or the air electrode current collection film | membrane 32 may be comprised from Ag (silver) and Ag-Pd (silver palladium alloy). The thickness of the air electrode current collector film 32 is, for example, about 50 to 500 μm.

[Current collecting member]
As shown in FIG. 2, the current collecting member 302 is disposed between the fuel battery cells 301. The current collector 302 electrically connects adjacent fuel cells 301 to each other in the thickness direction (z-axis direction) of the fuel cells 301. The current collecting member 302 is disposed on the proximal end portion 303 side.

  The current collecting member 302 is disposed on the proximal side of the power generation element portion 10 </ b> A located on the most proximal side (manifold 200 side) among the plurality of power generation element portions 10. Specifically, as shown in FIG. 6, the current collecting member 302 is disposed on the air electrode current collecting film 32 extending from the power generating element portion 10 </ b> A located on the most proximal side. “Proximal” and “distal” indicate the positional relationship in the longitudinal direction of the fuel cell 301 with respect to the manifold 200.

  As shown in FIG. 7, the current collecting member 302 has a block shape, for example, a rectangular parallelepiped shape or a columnar shape. The thickness t3 of the current collecting member 302 is preferably about 0.5 to 5 mm, for example. The thickness t3 of the current collecting member 302 refers to the dimension in the thickness direction (z-axis direction).

The current collecting member 302 is conductive, and is made of, for example, a sintered body of oxide ceramics. Examples of such oxide ceramics include perovskite oxide and spinel oxide. Examples of the perovskite oxide include (La, Sr) MnO ₃ , (La, Sr) (Co, Fe) O _{3, and the} like. Examples of the spinel oxide include (Mn, Co) ₃ O ₄ , (Mn, Fe) ₃ O _{4, and the} like. The current collecting member may be SOFC special steel (Fe—Cr alloy). For example, the current collecting member 302 does not have flexibility.

[Bonding material]
A pair of joining materials joins the pair of fuel cells 301 and the current collecting member 302. The pair of bonding materials includes a first bonding material 101a and a second bonding material 101b. Of the pair of bonding materials, the thinner bonding material is referred to as a first bonding material 101a, and the thicker bonding material is referred to as a second bonding material 101b. That is, the thickness (t2) of the second bonding material 101b is larger than the thickness (t1) of the first bonding material 101a.

  The thickness t1 of the first bonding material 101a is preferably about 0.05 to 1 mm. The thickness t2 of the second bonding material 101b is preferably about 0.1 to 2 mm. Here, the thickness t1 of the first bonding material 101a and the thickness t2 of the second bonding material 101b refer to dimensions in the thickness direction (z-axis direction). Further, the thickness of each of the bonding materials 101a and 101b refers to the distance between the current collecting member 302 and the fuel cell 301. That is, the thickness of the portion of each bonding material 101a, 101b that protrudes to the outer peripheral side of the current collecting member 302 is not considered.

  The ratio (t2 / t1) of the thickness t2 of the second bonding material 101b to the thickness t1 of the first bonding material 101a is preferably about 1.5 to 20, for example.

The first bonding material 101 a and the second bonding material 101 b are in contact with the entire end surfaces in the thickness direction of the current collecting member 302. The bonding area of each bonding material 101a, 101b and current collecting member 302 is preferably about 1 to 500 mm ² .

The first bonding material 101 and the second bonding material 101b are conductive, and are a sintered body of oxide ceramics, noble metal (Pt, Au, Ag), base metal (Ni, Ni-based alloy, composite of Ni and ceramics). It is formed by the material. Specifically, examples of the first bonding material 101 and the second bonding material 101b include perovskite oxide and spinel oxide. Examples of the perovskite oxide include (La, Sr) MnO ₃ , (La, Sr) (Co, Fe) O _{3, and the} like. The spinel oxide is formed of at least one selected from the group consisting of (Mn, Co) ₃ O ₄ , (Mn, Fe) ₃ O _{4, and the} like.

  As shown in FIG. 2, each fuel cell 301 is supported by the manifold 200. Specifically, each fuel cell 301 is fixed to the top plate 203 of the manifold 200 by the third bonding material 102. More specifically, as shown in FIG. 8, each fuel cell 301 is inserted into the through hole 202 of the manifold 200. The fuel battery cell 301 is fixed to the manifold 200 by the third bonding material 102 while being inserted into the through hole 202.

The third bonding material 102 is filled in the through hole 202 in a state where the fuel battery cell 301 is inserted. That is, the third bonding material 102 is filled in a gap between the outer peripheral surface of the fuel cell 301 and the wall surface that defines the through hole 202. The third bonding material 102 is, for example, crystallized glass. As the crystallized glass, for example, a SiO ₂ —B ₂ O ₃ system, a SiO ₂ —CaO system, or a SiO ₂ —MgO system may be employed. In this specification, crystallized glass means that the ratio (crystallinity) of “volume occupied by crystal phase” to the total volume is 60% or more, and “volume occupied by amorphous phase and impurities relative to the total volume”. "Indicates a glass having a ratio of less than 40%. As the material of the third bonding material 102, amorphous glass, brazing material, ceramics, or the like may be employed. Specifically, the third bonding material 102 is at least one selected from the group consisting of SiO ₂ —MgO—B ₂ O ₅ —Al ₂ O ₃ and SiO ₂ —MgO—Al ₂ O ₃ —ZnO. .

  The length of each fuel cell 301 protruding from the manifold 200 in the longitudinal direction (x-axis direction) can be about 100 to 300 mm. The fuel cells 301 are arranged at intervals in the thickness direction.

[Power generation method]
The fuel cell stack 100 configured as described above generates power as follows. By flowing fuel gas (hydrogen gas or the like) into the fuel gas flow path 21 of each fuel cell 301 through the manifold 200 and exposing both surfaces of the support substrate 20 to oxygen-containing gas (air or the like), the electrolyte 5 An electromotive force is generated by a difference in oxygen partial pressure generated between the two side surfaces. When this fuel cell stack 100 is connected to an external load, an electrochemical reaction represented by the following formula (1) occurs in the air electrode 6, and an electrochemical reaction represented by the following formula (2) occurs in the fuel electrode 4, causing a current to flow. .
(1/2) · O ₂ + 2e ⁻ → O ²⁻ (1)
H ₂ + O ²⁻ → H ₂ O + 2e ⁻ (2)

  For example, as shown in FIG. 9, the gas containing oxygen is supplied to the space between the current collecting member 302 and the manifold 200 so as to flow along the width direction. Specifically, the fuel cell stack 100 further includes a gas supply member 400. The gas supply member 400 is configured to supply a gas such as air between the current collecting members 302 and the top plate 203 of the manifold 200 between the fuel cells 301. Note that the guide plate 401 may be installed on the opposite side of the gas supply member 400 so that the gas supplied from the gas supply member 400 efficiently flows upward. The guide plate 401 has a flat plate shape and extends in the longitudinal direction of the fuel cell 301 and also extends in the thickness direction of the fuel cell 301.

[Production method]
Next, a method for manufacturing the fuel cell stack configured as described above will be described.

  First, a manifold 200 and a plurality of fuel cells 301 are prepared. Then, as shown in FIG. 10, the fuel cell cells 301 are connected to each other by the current collecting member 302, the first bonding material 101a, and the second bonding material 101b, and the cell assembly 300 is produced. At this stage, the first bonding material 101a and the second bonding material 101b are not fired, and the fuel cells 301 are temporarily fixed to each other.

  Next, as shown in FIG. 11, the lower end portion of each fuel cell 301 of the cell assembly 300 is inserted into each through hole 202 of the manifold 200. In addition, you may use the jig | tool for hold | maintaining a predetermined space | interval for each fuel cell 301 along the thickness direction.

  Next, as shown in FIG. 2, the third bonding material 102 is filled into the through hole 202 in a state where the fuel cell 301 is inserted. The third bonding material 102 is preferably filled to the extent that it protrudes upward from the surface of the support plate.

  Next, heat treatment is applied to the first bonding material 101a, the second bonding material 101b, and the third bonding material 102. By this heat treatment, the first bonding material 101a, the second bonding material 101b, and the third bonding material 102 are solidified, and the fuel cell stack 100 is completed. Specifically, the first bonding material 101a and the second bonding material 101b are fired by being subjected to heat treatment. As a result, each fuel cell 301 and the current collecting member 302 are fixed. In addition, the third bonding material 102 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 become crystallized glass. As a result, the third bonding material 102 made of crystallized glass functions, and the proximal end portion of each fuel cell 301 is fixed to the manifold 200. Thereafter, a predetermined jig is removed from the fuel cell stack 100. Various dimensions such as the thicknesses of the first bonding material 101a and the second bonding material 101b are dimensions after the heat treatment.

[Modification]
As mentioned above, although embodiment of this invention was described, this invention is not limited to these, A various change is possible unless it deviates from the meaning of this invention.

Modification 1
In the above embodiment, one current collecting member 302 is disposed between the pair of fuel cells 301, but the configuration of the fuel cell stack 100 is not limited to this. For example, as shown in FIG. 12, a plurality of current collecting members 302 may be disposed between a pair of fuel cells 301. The current collecting members 302 are arranged at intervals in the width direction (y-axis direction) of the fuel cell 301.

  As shown in FIG. 13, all the current collecting members 302 are close to one fuel cell 301 (the left fuel cell in FIG. 13). That is, in the thickness direction (z-axis direction) of the fuel cell 301, all of the bonding materials disposed on the first side (the left side in FIG. 13) of the current collecting member 302 are the first bonding material 101a, and the current collecting member All the bonding materials arranged on the second side 302 (the right side in FIG. 13) are the second bonding materials 101b. The arrangement of the first and second bonding materials 101a and 101b is not particularly limited to this. For example, as shown in FIG. 14, a current collecting member 302 close to one fuel battery cell 301 and a current collecting member 302 close to the other fuel battery cell 301 may be mixed. That is, in the thickness direction (z-axis direction) of the fuel cell 301, the first bonding material 101a disposed on the first side (the left side in FIG. 14) of the current collecting member 302 and the second side of the current collecting member 302 The 1st joining material 101a arrange | positioned (right side of FIG. 14) may be mixed.

Modification 2
In the said embodiment, although each current collection member 302 has connected the adjacent fuel battery cells 301 in the proximal end part 303 side of each fuel battery cell 301, a connection location is not limited to this. For example, as shown in FIG. 15, each current collecting member 302 may connect adjacent fuel cells 301 at the distal end 304 of each fuel cell 301.

Modification 3
In the above embodiment, the present invention is applied to a cylindrical flat plate type fuel cell stack, but the present invention can also be applied to other types of fuel cell stacks. For example, as shown in FIG. 16, the present invention can be applied to a flat plate fuel cell stack 100. In this case, a separator may be employed as the current collecting member 302. That is, the separator 302 having a function as a current collecting member is disposed between the fuel battery cells 301. The separator 302 electrically connects adjacent fuel cells 301 to each other. Each fuel cell 301 and the separator 302 are joined by the first joining material 101a or the second joining material 101b.

Modification 4
In addition, when the present invention is applied to the flat plate fuel cell stack 100, the fuel cell stack 100 may be configured as shown in FIG. That is, one of the first bonding material 101 a and the second bonding material 101 b bonds the current collector 302 and the separator 305. Then, the other of the first bonding material 101 a and the second bonding material 101 b bonds the current collecting member 302 and the fuel cell 301. The separator 103 is disposed so as to face the fuel battery cell 301.

  The present invention will be described more specifically with reference to the following examples and comparative examples. In addition, this invention is not limited to the following Example.

Fuel cell stacks according to Examples 1 to 10 and Comparative Examples 1 to 2 were produced as follows.

  First, the current collecting member 302 was disposed between the pair of fuel cells 301 configured as described above. And each fuel cell 301 and the current collection member 302 were joined by the 1st joining material 101a and the 2nd joining material 101b. The pair of fuel cells 301 joined by the first joining material 101a, the second joining material 101b, and the current collecting member 302 are inserted into the through holes 202 of the manifold 200 and joined by the third joining material 102. . Then, the first bonding material 101a, the second bonding material 101b, and the third bonding material 102 were solidified by heat treatment.

  The materials constituting the current collecting member 302, the first bonding material 101a, and the second bonding material 101b in each sample manufactured as described above are as shown in Table 1. The thickness t1 of the first bonding material 101a and the thickness t2 of the second bonding material 101b are as shown in Table 1. The thickness t1 of the first bonding material 101a and the thickness t2 of the second bonding material 101b control the organic component ratio, viscosity, and coating amount of the bonding material paste to be applied, and the current collecting member 302 is installed. The subsequent pressing was controlled and adjusted.

  The thicknesses t1 and t2 of the bonding materials 101a and 101b were measured in the following manner after evaluation described later. First, the fuel cell stack 100 was cut along a horizontal plane passing through the first bonding material 101a, the second bonding material 101b, and the current collecting member 302. On this cut surface, the thickness t1 of the first bonding material 101a and the thickness t2 of the second bonding material 101b were measured at arbitrary five points with a dimension measuring instrument with a microscope. Each thickness shown in Table 1 is an average value of each.

(Evaluation method)
As a result of the following evaluation of the bondability of each sample produced as described above, the results shown in Table 1 were obtained.

  As shown in Table 1, in the fuel cell stack according to Comparative Example 1, poor bonding properties due to the first or second bonding materials 101a and 101b occurred. That is, the first or second bonding material 101a, 101b could not follow the warp of the fuel cell 301, and peeling was observed between the current collecting member 302 and the fuel cell 301.

In the fuel cell stack according to Comparative Example 2 , cracks occurred in the second bonding material 101b. This is presumably because the ratio (t2 / t1) of the fuel cell stack according to Comparative Example 2 is larger than 20, so that the shrinkage associated with the drying of the paste for the second bonding material 101b increases. On the other hand, in the fuel cell stacks according to Examples 1 to 10, since the ratio (t2 / t1) was set to 1.5 to 20, the above-described problem did not occur and good results were obtained.

100: Fuel cell stack 101a: First bonding material 101b: Second bonding material 200: Manifold 203: Top plate 301a: First fuel cell 301b: Second fuel cell 302: Current collecting member

Claims (7)

A corresponding pair of fuel cells;
A current collecting member disposed between the fuel cells and electrically connecting the fuel cells to each other;
A pair of conductive bonding materials for bonding the current collecting member and the fuel cells, and
With
The pair of bonding material, possess a first bonding material, and a thick second joining material than the first bonding material,
The ratio of the thickness of the second bonding material to the thickness of the first bonding material is 1.5 to 2.0.
Fuel cell stack. A fuel cell;
A separator disposed to face the fuel battery cell;
A current collecting member disposed between the fuel battery cell and the separator, and electrically connecting the fuel battery cell and the separator;
A pair of bonding materials for connecting the current collecting member and the fuel cell, and for connecting the current collecting member and the separator;
With
The pair of bonding material, possess a first bonding material, and a thick second joining material than the first bonding material,
The ratio of the thickness of the second bonding material to the thickness of the first bonding material is 1.5 to 2.0.
Fuel cell stack. The first and second bonding materials are formed of conductive ceramics.
The fuel cell stack according to claim 1 or 2. The current collecting member has a block shape,
The fuel cell stack according to any one of claims 1 to 3. The current collecting member is composed of a fired body of conductive oxide ceramics,
The fuel cell stack according to any one of claims 1 to 4. Further comprising a manifold for supplying gas to each fuel cell,
Each of the fuel cells extends upward from the top plate of the manifold.
The fuel cell stack according to any one of claims 1 and 3 to 5. The first bonding material and the second bonding material are made of the same material.
The fuel cell stack according to any one of claims 1 to 6.

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