JP2019215985A - Metal member for electrochemical cell, and electrochemical cell assembly using the same - Google Patents

Abstract

To suppress oxidation in a body.SOLUTION: A metal member 310 for an electrochemical cell includes a body 311. The body 311 has a first main surface Sa1, a second main surface Sa2, and a side surface Sa3. The first main surface Sa1 faces an electrochemical cell 300a side. The second main surface Sa2 is a main surface on a side opposite to the first main surface Sa1. The body 311 further has a projection 319 and a curved surface Sa4. The projection 319 projects, from a corner formed by the second main surface Sa2 and the side surface Sa3, in a direction where the second main surface Sa2 faces. The curved surface Sa4 connects the first main surface Sa1 and the side surface Sa3.SELECTED DRAWING: Figure 10

Description

  The present invention relates to a metal member for an electrochemical cell and an electrochemical cell assembly using the same.

  2. Description of the Related Art In recent years, attention has been focused on a cell stack using a fuel cell, which is a type of electrochemical cell, from the viewpoint of environmental issues and effective use of energy resources. A fuel cell generally has a fuel electrode, an air electrode, and a solid electrolyte layer. The cell stack has a plurality of fuel cells. In order to electrically connect adjacent fuel cells to each other, a current collecting member, which is a metal member, is joined to each fuel cell. In addition, a metal member may be joined to the fuel cell for other uses such as extracting current from the fuel cell.

JP 2014-127427 A

  The main body of the current collecting member may be oxidized by an oxidant gas or the like. When the main body of the current collecting member is oxidized, there is a problem that the electric resistance in the main body increases and the power taken out decreases. Therefore, an object of the present invention is to suppress oxidation in the main body.

  The metal member for an electrochemical cell according to the first aspect of the present invention is a metal member joined to the electrochemical cell. The metal member for an electrochemical cell has a main body. The main body has a first main surface, a second main surface, and side surfaces. The first main surface faces the electrochemical cell side. The second main surface is a main surface opposite to the first main surface. The main body further has a protrusion and a curved surface. The protrusion protrudes from a corner formed by the second main surface and the side surface in a direction in which the second main surface faces. The curved surface connects the first main surface and the side surface.

  According to this configuration, since the first main surface and the side surface are connected by the curved surface on the electrochemical cell side, the conventional main body portion that directly connects the first main surface and the side surface to form a corner portion It is possible to suppress the current from being concentrated as compared with the case of (1). As a result, oxidation in this portion can be suppressed. In addition, the protrusion protrudes from a corner formed by the second main surface and the side surface in a direction toward the second main surface. For this reason, this projection is preferentially oxidized, so that oxidation of other portions can be suppressed.

  Preferably, the metal member for an electrochemical cell further includes a coating layer. The coating layer covers the main body. The side surface has a first region on the first main surface side and a second region on the second main surface side. Then, the surface roughness in the second region is larger than the surface roughness in the first region.

  Preferably, the thickness of the coating layer in the second region is greater than the thickness of the coating layer in the first region.

  Preferably, the thickness of the covering layer in the first region is greater than the thickness of the covering layer in the second region.

  Preferably, the main body has a through hole. And the inner wall surface of this through-hole is constituted by the side surface described above.

  Preferably, the surface roughness in the second region is larger than the surface roughness in the first and second main surfaces.

  An electrochemical cell assembly according to a second aspect of the present invention includes an electrochemical cell, any one of the above-described metal members for an electrochemical cell, and a conductive bonding material. The metal member for an electrochemical cell is disposed with the first main surface facing the electrochemical cell side. The conductive bonding material bonds the metal member to the electrochemical cell.

  ADVANTAGE OF THE INVENTION According to this invention, oxidation in a main-body part can be suppressed.

FIG. 2 is a perspective view of a cell stack device. Sectional drawing of a cell stack apparatus. FIG. 3 is a perspective view of a fuel manifold. The perspective view of a fuel cell. Sectional drawing of a fuel cell. FIG. 3 is a cross-sectional view of the base end side of the fuel cell. FIG. 4 is a perspective view of a current collecting member. AA sectional drawing of FIG. Sectional drawing which shows an example of a manufacturing method. The enlarged view of the side of the 1st junction. The enlarged view of the 2nd main surface of the 1st junction.

  Hereinafter, an embodiment of a cell stack device using a current collecting member as an example of a metal member for an electrochemical cell according to the present invention will be described with reference to the drawings.

  As shown in FIGS. 1 and 2, the cell stack device 100 includes a fuel manifold 200 and a plurality of fuel cells 300.

[Fuel manifold]
As shown in FIG. 3, the fuel manifold 200 is configured to distribute a fuel gas (for example, hydrogen or the like) to each of the fuel cells 300. The fuel manifold 200 is hollow and has an internal space. Fuel gas is supplied to the internal space of the fuel manifold 200 via the introduction pipe 201. The fuel manifold 200 has a plurality of insertion holes 202 arranged at intervals. Each insertion hole 202 is formed in a top plate 203 of the fuel manifold 200. Each insertion hole 202 communicates with the internal space of the fuel manifold 200 and the outside.

[Fuel cell]
As shown in FIG. 2, each fuel cell 300 extends from the fuel manifold 200. Specifically, each fuel cell 300 extends upward (x-axis direction) from the top plate 203 of the fuel manifold 200. That is, the longitudinal direction (x-axis direction) of each fuel cell 300 extends upward. The length of each fuel cell 300 in the longitudinal direction (x-axis direction) can be about 100 to 300 mm.

The base end of each fuel cell 300 is inserted into the insertion hole 202 of the fuel manifold 200. Each fuel cell 300 is fixed to the insertion hole 202 by the bonding material 101. The fuel cell 300 is fixed to the fuel manifold 200 by the bonding material 101 while being inserted into the insertion hole 202. The bonding material 101 is filled in the gap between the fuel cell 300 and the insertion hole 202. Examples of the bonding material 101 include crystallized glass, amorphous glass, brazing material, and ceramics. The term “crystallized glass” means that the ratio (crystallinity) of “volume occupied by a crystalline phase” to the whole volume is 60% or more, and the ratio of “volume occupied by an amorphous phase and impurities” to the whole volume is less than 40%. Glass. Examples of such crystallized glass include, for example, SiO ₂ —B ₂ O ₃ , SiO ₂ —CaO, and SiO ₂ —MgO.

  Each fuel cell 300 is formed in a plate shape extending in the longitudinal direction (x-axis direction) and the width direction (y-axis direction). The fuel cells 300 are arranged at intervals in the arrangement direction (z-axis direction). The interval between two adjacent fuel cells 300 is not particularly limited, but may be about 1 to 5 mm. Two adjacent fuel cells 300 are electrically connected by a current collecting member 310. A cell stack is formed by connecting a plurality of fuel cells 300 with a current collecting member 310. The configuration of the current collecting member 310 will be described later.

  The fuel cell 300 includes a plurality of power generation elements 10 and a support substrate 20.

[Support substrate]
As shown in FIG. 4, the support substrate 20 has therein a plurality of gas channels 21 extending along the longitudinal direction (x-axis direction) of the support substrate 20. Each gas flow path 21 extends from the base end side of the support substrate 20 toward the front end side. Each gas passage 21 extends substantially parallel to each other. In addition, the base end side means the gas supply side of the gas flow path. Specifically, when the fuel cell 300 is attached to the fuel manifold 200, it means a side closer to the fuel manifold 200. Further, the front end side means the opposite side of the gas flow path from the gas supply side. Specifically, when the fuel cell 300 is attached to the fuel manifold 200, it means a side far from the fuel manifold 200. For example, in the example shown in FIG. 2, the lower side is the base end side and the upper side is the distal end side.

  As shown in FIG. 5, the support substrate 20 has a plurality of first concave portions 22. In the present embodiment, each of the first concave portions 22 is formed on both main surfaces of the support substrate 20, but may be formed on only one main surface. The first recesses 22 are arranged at intervals in the longitudinal direction of the support substrate 20.

The support substrate 20 is made of a porous material having no electron conductivity. The support substrate 20 can be composed 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, it may be composed of MgO (magnesium oxide) and MgAl ₂ O ₄ (magnesia alumina spinel). The porosity of the support substrate 20 is, for example, about 20 to 60%.

[Power generation element]
Each power generation element unit 10 is supported by a support substrate 20. In the present embodiment, each power generating element unit 10 is formed on both main surfaces of the support substrate 20, but may be formed on only one main surface. The power generating elements 10 are arranged at intervals in the longitudinal direction of the support substrate 20. That is, the fuel cell 300 according to the present embodiment is a so-called horizontal stripe fuel cell. The power generation element units 10 adjacent in the longitudinal direction are electrically connected to each other by an interconnector 31.

  The power generation element unit 10 has a fuel electrode 4, an electrolyte 5, and an air electrode 6. Further, the power generation element unit 10 further has a reaction prevention film 7.

[Fuel electrode]
The fuel electrode 4 is a fired body made of a porous material having electron conductivity. The anode 4 has an anode current collector 41 and an anode active section 42.

  The anode current collector 41 is disposed in the first recess 22. Specifically, the anode current collector 41 is filled in the first recess 22 and has the same outer shape as the first recess 22. The fuel electrode current collector 41 has a second recess 411 and a third recess 412. The fuel electrode active part 42 is arranged in the second recess 411. Further, the interconnector 31 is arranged in the third recess 412.

  The fuel electrode current collector 41 has electron conductivity. The anode current collector 41 preferably has higher electron conductivity than the anode active part 42. The fuel electrode current collector 41 may or may not have oxygen ion conductivity.

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

  The fuel electrode active part 42 has oxygen ion conductivity and electron conductivity. The anode active part 42 has a higher content of a substance having oxygen ion conductivity than the anode current collector 41. More specifically, the volume ratio of the substance having oxygen ion conductivity to the entire volume excluding the pore portion in the anode active portion 42 is determined by the ratio of the oxygen ion conductivity to the entire volume excluding the pore portion in the anode current collector 41. It is larger than the volume ratio of the substance having the property.

  The fuel electrode active portion 42 can be composed of, for example, NiO (nickel oxide) and YSZ (8YSZ) (yttria stabilized zirconia). Alternatively, the fuel electrode active portion 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.

[Electrolytes]
The electrolyte 5 is disposed so as to cover the fuel electrode 4. Specifically, the electrolyte 5 extends in a longitudinal direction from one interconnector 31 to an adjacent interconnector 31. That is, in the longitudinal direction (x-axis direction) of the support substrate 20, the electrolytes 5 and the interconnectors 31 are arranged alternately and continuously. The electrolyte 5 is configured to cover the first and second main surfaces of the support substrate 20.

  The electrolyte 5 is a fired body made of a dense material having ion conductivity and no electron conductivity. The electrolyte 5 can be composed of, for example, YSZ (8YSZ) (yttria-stabilized zirconia). Alternatively, the electrolyte 5 may be composed of LSGM (lanthanum gallate). The thickness of the electrolyte 5 is, for example, about 3 to 50 μm.

[Reaction prevention film]
The reaction prevention film 7 is a fired body made of a dense material. The reaction prevention film 7 is disposed between the electrolyte 5 and the cathode active portion 61. The reaction prevention film 7 suppresses the occurrence of a phenomenon in which YSZ in the electrolyte 5 reacts with Sr in the air electrode 6 to form a reaction layer having a large electric resistance at the interface between the electrolyte 5 and the air electrode 6. It is provided in.

The reaction prevention film 7 is made of a material containing ceria containing a rare earth element. The reaction prevention film 7 can be made of, for example, GDC = (Ce, Gd) O ₂ (gadolinium-doped ceria). The thickness of the reaction prevention film 7 is, for example, about 3 to 50 μm.

[Air electrode]
The air electrode 6 is a fired body made of a porous material having electron conductivity. The air electrode 6 is disposed on the side opposite to the fuel electrode 4 with respect to the electrolyte 5. The air electrode 6 has an air electrode active part 61 and an air electrode current collecting part 62.

  The cathode active part 61 is disposed on the reaction prevention film 7. The air electrode active portion 61 has oxygen ion conductivity and electron conductivity. The cathode active portion 61 has a higher content of a substance having oxygen ion conductivity than the cathode current collector 62. More specifically, the volume ratio of the substance having oxygen ion conductivity to the total volume excluding the pore portion in the cathode active portion 61 is determined by the oxygen ion conductivity in the cathode current collecting portion 62 relative to the entire volume excluding the pore portion. It is larger than the volume ratio of the substance having the property.

The cathode active portion 61 can be composed of, for example, LSCF = (La, Sr) (Co, Fe) O ₃ (lanthanum strontium cobalt ferrite). Alternatively, the air electrode active portion 61 is configured such that 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 active portion 61 may be configured by two layers of a first layer (inner layer) made of LSCF and a second layer (outer layer) made of LSC. The thickness of the air electrode active part 61 is, for example, 10 to 100 μm.

  The air electrode current collector 62 is arranged on the air electrode active unit 61. Further, the air electrode current collector 62 extends from the air electrode active part 61 toward an adjacent power generation element part. The fuel electrode current collector 41 and the air electrode current collector 62 extend from the power generation region to opposite sides. The power generation region is a region where the fuel electrode active portion 42, the electrolyte 5, and the air electrode active portion 61 overlap.

  The air electrode current collector 62 is a fired body made of a porous material having electron conductivity. The cathode current collector 62 preferably has higher electron conductivity than the cathode active unit 61. The air electrode current collector 62 may or may not have oxygen ion conductivity.

The air electrode current collector 62 can be composed of, for example, LSCF = (La, Sr) (Co, Fe) O ₃ (lanthanum strontium cobalt ferrite). Alternatively, the air electrode current collector 62 may be made of LSC = (La, Sr) CoO ₃ (lanthanum strontium cobaltite). Alternatively, the air electrode current collector 62 may be made of Ag (silver) or Ag-Pd (silver-palladium alloy). The thickness of the air electrode current collector 62 is, for example, about 50 to 500 μm.

[Interconnector]
The interconnector 31 is configured to electrically connect the power generating element units 10 adjacent in the longitudinal direction (x-axis direction) of the support substrate 20. In detail, the air electrode current collector 62 of one power generation element 10 extends toward the other power generation element 10. Further, the anode current collector 41 of the other power generation element 10 extends toward the one power generation element 10. Then, the interconnector 31 electrically connects the air electrode current collector 62 of the one power generation element unit 10 and the fuel electrode current collector 41 of the other power generation element unit 10. The interconnector 31 is arranged in the third recess 412 of the anode current collector 41. Specifically, the interconnector 31 is embedded in the third recess 412.

The interconnector 31 is a fired body made of a dense material having electron conductivity. The interconnector 31 can be made of, for example, LaCrO ₃ (lanthanum chromite). Alternatively, the interconnector 31 may be composed of (Sr, La) TiO ₃ (strontium titanate). The thickness of the interconnector 31 is, for example, 10 to 100 μm.

[Current collecting member]
As shown in FIG. 6, two adjacent fuel cells 300 (a first fuel cell 300a and a second fuel cell 300b) are electrically connected by a current collecting member 310. The current collecting member 310 is disposed between the first fuel cell 300a and the second fuel cell 300b. The current collecting member 310 is disposed closer to the base end side than the base end side power generation element section 10a arranged closest to the base end side among the plurality of power generation element sections 10 arranged on both main surfaces of the support substrate 20. I have.

  The current collecting member 310 is joined to a base end of each of the first fuel cell 300a and the second fuel cell 300b. Specifically, the current collecting member 310 includes an electric connection portion 110 extending from the base end power generation element portion 10a of the first fuel cell 300a and a base of the second fuel cell 300b via the conductive bonding material 102. It is joined to the air electrode current collector 62 extending from the end power generation element 10a. The first fuel cell 300a, the conductive bonding material 102, and the current collecting member 310 form an electrochemical cell assembly.

As the conductive bonding material 102, a known conductive ceramic or the like can be used. For example, the conductive bonding material 102 is made of at least one selected from (Mn, Co) ₃ O ₄ , (La, Sr) MnO ₃ , (La, Sr) (Co, Fe) O _{3, and the} like. Can be.

  FIG. 7 is a perspective view of the current collecting member 310. FIG. 7 shows a state where the current collecting member 310 is joined to the first fuel cell 300a. In FIG. 7, the second fuel cell 300b is omitted, but the second fuel cell 300b is actually arranged to face the first fuel cell 300a.

  The current collecting member 310 has a plate shape. For example, the current collecting member 310 can be configured by a bent metal plate (for example, a stainless plate). The current collecting member 310 includes a first joint 311, a second joint 312, a first connection 313, and a second connection 314.

  The first joint 311 is joined to the first fuel cell 300a. More specifically, the first joining portion 311 is joined by the conductive joining material 102 to the electric connection portion 110 extending from the base end power generation element portion 10a (see FIG. 6) of the first fuel cell 300a. The electrical connection unit 110 has a first connection unit 111 and a second connection unit 112. The first connecting portion 111 can have the same configuration and material as the interconnector 31 described above. In addition, the second connection portion 112 can be made of the same material as the above-described air electrode current collector 62. The second connecting portion 112 is electrically connected to the first connecting portion 111 and extends downward.

  The first joint 311 is formed in a flat plate shape. In the present embodiment, the first joint 311 is formed in a rectangular shape extending in the width direction, but the shape of the first joint 311 is not particularly limited, and may be a polygon having a triangle or more, a circle, an ellipse, or Other complicated shapes may be used.

  A plurality of first through holes 315 are formed in the first joint 311. Each first through hole 315 is filled with the conductive bonding material 102. Thereby, the joining force of the first joining portion 311 to the first fuel cell 300a can be improved. The conductive bonding material 102 may protrude outward from each of the first through holes 315, and may further spread on the outer surface of the first bonding portion 311.

  In the present embodiment, each of the first through holes 315 is formed in a rectangular shape extending along the width direction, but the shape of each of the first through holes 315 is not particularly limited, and may be a circle, an ellipse, a triangle or more. It may be a polygon or a complicated shape other than these. Further, in the present embodiment, three first through holes 315 are provided, but the number and positions of the first through holes 315 can be appropriately changed.

  The second joint 312 is electrically connected to the first joint 311. The second joint 312 is joined to the second fuel cell 300b. Specifically, the second bonding portion 312 is bonded to the air electrode current collecting portion 62 extending from the base power generation element portion 10a (see FIG. 6) of the second fuel cell 300b by the conductive bonding material 102. The second joint 312 faces the first joint 311 in the arrangement direction.

  The second joint 312 is formed in a flat plate shape. In the present embodiment, the second joint 312 has the same shape as the first joint 311, but may have a different shape from the first joint 311. The shape of the second joint 312 is not particularly limited, and may be a polygon having more than a triangle, a circle, an ellipse, or a complicated shape other than these.

  A plurality of second through holes 316 are formed in the second joint 312. Each second through hole 316 is filled with the conductive bonding material 102. Thereby, the joining force of the second joining portion 312 to the second fuel cell 300b can be improved. The conductive bonding material 102 may protrude outward from each of the second through holes 316, and may further spread on the outer surface of the second bonding portion 312.

  In the present embodiment, each second through-hole 316 is formed in a rectangular shape extending along the width direction, but the shape of each second through-hole 316 is not particularly limited, and may be a circle, an ellipse, a triangle or more. It may be a polygon or a complicated shape other than these. In the present embodiment, three second through holes 316 are provided, but the number and position of the second through holes 316 can be changed as appropriate.

  The first and second connecting portions 313 and 314 are connected to the first connecting portion 311 and the second connecting portion 312, respectively. In the present embodiment, the first and second connecting portions 313 and 314 are each curved, but are not limited thereto. Each of the first and second connecting portions 313 and 314 may have a flat plate shape, or may have a shape that is bent at at least one position.

  In the present embodiment, the first and second connecting portions 313 and 314 are arranged at both ends of the current collecting member 310, but the positions of the first and second connecting portions 313 and 314 are not particularly limited.

[Cross section of joint]
FIG. 8 is an enlarged view of an AA cross section of FIG. FIG. 8 is a cross-sectional view of a portion between the adjacent first through holes 315 in the first joint 311.

  The first joining portion 311 of the current collecting member 310 has a first main surface Sa1, a second main surface Sa2, and a plurality of side surfaces Sa3. The first joint 311 corresponds to the main body of the present invention. The thickness of the first joint 311 is, for example, about 0.1 to 2.0 mm.

  The first main surface Sa1 of the first joint 311 faces the first fuel cell 300a side. The first main surface Sa1 of the first joining portion 311 is joined to the first fuel cell 300a via the conductive joining material 102.

  The second main surface Sa2 faces the side opposite to the first main surface Sa1. That is, the second main surface Sa2 faces the space between the first fuel cell 300a and the second fuel cell 300b. When an oxidizing gas such as air flows on the outer surface of the fuel cell 300, such as between the first fuel cell 300a and the second fuel cell 300b, the oxidizing gas flows through the second main surface Sa2. It faces the flowing space.

  The side surface Sa3 is a surface that extends in the thickness direction (z-axis direction) of the first joint 311. The side surface Sa3 extends between the first main surface Sa1 and the second main surface Sa2. The side surface Sa3 illustrated in FIG. 8 is an inner wall surface that defines the first through hole 315. That is, a portion of the first joining portion 311 disposed between the pair of first through holes 315 has the pair of side surfaces Sa3.

  The side surface Sa3 has a first region R1 and a second region R2. The first region R1 is a region on the first main surface Sa1 side of the side surface Sa3. That is, the first region R1 is a region on the side of the first fuel cell 300a in the side surface Sa3. Although not particularly limited, for example, the first region R1 occupies a range of about 10 to 90% of the side surface Sa3.

  The second region R2 is a region on the second main surface Sa2 side of the side surface Sa3. That is, the second region R2 is a region on the side of the side surface Sa3 apart from the first fuel cell 300a. Although not particularly limited, for example, the second region R2 occupies a range of about 10 to 90% of the side surface Sa3.

  In the second region R2, a plurality of irregularities are formed on the side surface Sa3. For example, the plurality of irregularities are arranged along the direction in which the first and second main surfaces Sa1 and Sa2 extend (y-axis direction or x-axis direction).

  The surface roughness of the side surface Sa3 is different between the first region R1 and the second region R2. The surface roughness in the second region R2 is larger than the surface roughness in the first region R1. Specifically, the arithmetic average roughness in the second region R2 is larger than the arithmetic average roughness in the first region R1.

  For example, the arithmetic average roughness in the second region R2 can be made larger than the arithmetic average roughness in the first region R1 by blasting. More specifically, as shown in FIG. 9, the second main surface Sa2 of the first joint 311 is masked, and an abrasive is struck diagonally from above with the second main surface Sa2 side facing upward. Note that the arrows in FIG. 9 indicate the direction in which the abrasive is discharged. By this blasting, the arithmetic average roughness in the second region R2 can be made larger than the arithmetic average roughness in the first region R1. Note that, although not particularly limited, the surface roughness of the side surface Sa3 in the second region R2 is larger than the surface roughness of the first and second main surfaces Sa1 and Sa2.

  For example, the arithmetic average roughness in the second region R2 is approximately 0.12 to 10 μm, and the arithmetic average roughness in the first region R1 is approximately 0.10 to 2.0 μm. The ratio of the arithmetic average roughness in the second region R2 to the arithmetic average roughness in the first region R1 is 1.2 to 30.

  In addition, the surface roughness of the first region R1 can be measured as follows. First, after the first bonding portion 311 is filled with resin, mechanical polishing is performed in parallel with the first main surface Sa1. More specifically, the polishing is performed from the first main surface Sa1 side in three steps of 2.5% (T / 40) of the thickness T of the first bonding portion 311 in three steps. Then, the surface roughness (arithmetic mean roughness) in the first region R1 is measured by image processing from the cross-sectional shape obtained by SEM observation every three times of polishing. Then, a value obtained by averaging the three surface roughnesses (arithmetic average roughness) can be used as the surface roughness of the first region R1.

  Further, the surface roughness of the second region R2 can be measured as follows. First, after the first bonding portion 311 is filled with resin, mechanical polishing is performed in parallel with the second main surface Sa2. Specifically, the polishing is performed from the second main surface Sa2 side in three steps of 2.5% (T / 40) of the thickness T of the first bonding portion 311. Then, every three times of polishing, the surface roughness (arithmetic average roughness) in the second region R2 is measured by image processing from the cross-sectional shape obtained by SEM observation. Then, a value obtained by averaging the three surface roughnesses (arithmetic average roughness) can be used as the surface roughness of the second region R2.

  FIG. 10 is an enlarged view of the side surface Sa3 of the first joint 311. As shown in FIG. 10, the first joining portion 311 has a step portion 318 formed between the first region R1 and the second region R2. The step portion 318 has a step (dimension in the x-axis direction) of, for example, about 1 to 400 μm. The step portion 318 can be formed, for example, by press working with a mold having a desired step shape.

  The ratio (T2 / T1) of the thickness T2 of the second region R2 to the thickness T1 of the first region R1 is, for example, about 0.1 to 9.0.

  The first joint 311 has a protrusion 319. The protrusion 319 protrudes from a corner formed by the second main surface Sa2 and the side surface Sa3 in a direction in which the second main surface Sa2 faces (upward in FIG. 10). That is, a portion of the first joining portion 311 disposed between the pair of first through holes 315 has the pair of protrusions 319. The protrusion 319 is formed so as to become thinner toward the tip in the cross-sectional shape. The protrusion 319 can be formed by, for example, press working with a mold having a desired protrusion shape.

  The height H1 of the protrusion 319 is, for example, about 1 to 200 μm. The protrusion 319 is covered with the covering layer 317. The ratio (H1 / T3) of the height H1 of the projection 319 to the thickness T3 of the coating layer 317 in the portion covering the projection 319 is, for example, about 0.02 to 200. Note that the thickness T3 of the coating layer 317 is determined by the point at which the line extending from the tip of the projection 319 in the thickness direction (z-axis direction) of the first joint 311 intersects with the outer peripheral surface of the coating layer 317. The dimension is between the base of the part 319 and the base.

  The first joint 311 has a curved surface Sa4. The curved surface Sa4 connects the first main surface Sa1 and the side surface Sa3. That is, a portion of the first joining portion 311 disposed between the pair of first through holes 315 has the pair of curved surfaces Sa4. The curved surface Sa4 is curved so as to expand outward. The cross-sectional shape of the curved surface Sa4 is an arc shape. The curved surface Sa4 can be formed by chamfering a corner formed by the first main surface Sa1 and the side surface Sa3. Although not particularly limited, the radius of curvature of the curved surface Sa4 is, for example, about 30 to 1000 μm.

  As shown in FIG. 11, the ratio (L2 / L1) of the distance L2 between the pair of curved surfaces Sa4 to the distance L1 between the pair of side surfaces Sa3 is about 0.50 to 0.99.

  The first joint 311 is made of an alloy material containing Cr (chromium). As such a metal material, Fe—Cr alloy steel (such as stainless steel) and Ni—Cr alloy steel can be used. The content ratio of Cr in the first joint 311 is not particularly limited, but may be 4 to 30% by mass.

The first joint 311 may contain Ti (titanium) or Al (aluminum). Although the content ratio of Ti in the first joint 311 is not particularly limited, it is 0.01 to 1.0 at. %. The content ratio of Al in the first joining portion 311 is not particularly limited, but is 0.01 to 0.4 at. %. The first joining portion 311 may contain Ti as TiO ₂ (titania) or may contain Al as Al ₂ O ₃ (alumina).

  Note that the second joint 312, the first joint 313, and the second joint 314 can also be made of the same material as the first joint 311.

  The current collecting member 310 has a coating layer 317. The coating layer 317 covers the first joint 311, the second joint 312, the first connection 313, and the second connection 314. Since the coating layer 317 covers the first joint portion 311, the second joint portion 312, the first connection portion 313, and the second connection portion 314 in this manner, the volatilization of Cr from these can be suppressed. As a result, Cr poisoning in the air electrode 6 of each fuel cell 300 is suppressed.

  Specifically, the coating layer 317 is formed on the first main surface Sa1, the second main surface Sa2, and the side surface Sa3 of the first joint 311. The thickness of the coating layer 317 is not particularly limited, but can be, for example, about 1.0 to 200 μm.

  On the side surface Sa3, the thickness of the coating layer 317 in the first region R1 is different from the thickness of the coating layer 317 in the second region R2. The thickness of the coating layer 317 in the second region R2 is larger than the thickness of the coating layer 317 in the first region R1. In this case, the thickness of the covering layer 317 in the second region R2 can be about 1.1 to 200 μm, and the thickness of the covering layer 317 in the first region R1 can be about 1.0 to 100 μm. The ratio of the thickness of the coating layer 317 in the second region R2 to the thickness of the coating layer 317 in the first region R1 can be about 1.1 to 50. In addition, the thickness of the coating layer 317 may be adjusted to be greater than the thickness of the first region R1 by adjusting the thickness when the coating layer forming slurry is applied, for example. it can.

  The thickness of the coating layer 317 in the first region R1 can be measured from the cross-sectional shape used when measuring the surface roughness in the first region R1 described above. Specifically, the thickness of the coating layer 317 is measured at any 10 positions in each cross-sectional shape. Then, the average value of the thickness of the coating layer 317 at the total of 30 points is defined as the thickness of the coating layer 317 in the first region R1.

  Further, the thickness of the coating layer 317 in the second region R2 can be measured from the cross-sectional shape used when measuring the surface roughness in the second region R2 described above. Specifically, the thickness of the coating layer 317 is measured at any 10 positions in each cross-sectional shape. Then, the average value of the thickness of the coating layer 317 at the total of 30 points is defined as the thickness of the coating layer 317 in the second region R2.

  As a material for forming the coating layer 317, a ceramic material can be used. The specific type of the ceramic material can be appropriately selected according to the application location. In the present embodiment, since the current collecting member 310 is required to have conductivity, the ceramic material is made of a perovskite-type composite oxide containing La and Sr, or a transition metal such as Mn, Co, Ni, Fe, Cu, or the like. For example, a spinel-type composite oxide can be used. However, the coating layer 317 only needs to be able to suppress the volatilization of Cr, and its constituent material is not limited to a ceramic material.

  The conductive bonding material 102 covers the entire first main surface Sa1 of the first bonding portion 311 via the coating layer 317, and also covers the side surface Sa3. Note that the conductive bonding material 102 mainly covers the first region R1 of the side surface Sa3 via the coating layer 317. The conductive bonding material 102 covers only a part of the side surface Sa3 on the second region R2 side. Alternatively, the conductive bonding material 102 does not cover the second region R2.

  As described above, the configuration of the first joining portion 311 of the current collecting member 310 has been described. However, it is preferable that this configuration is also applied to the second joining portion 312 of the current collecting member 310.

(Modification of Embodiment)
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, the case where the current collecting member 310, which is an embodiment of the metal member for an electrochemical cell according to the present invention, is applied to a horizontal stripe fuel cell, but also to a so-called vertical stripe fuel cell and the like. Can be applied. The vertical stripe type fuel cell is composed of a conductive support substrate, a power generation unit (a fuel electrode, a solid electrolyte layer, and an air electrode) disposed on one main surface of the support substrate, and disposed on another main surface of the support substrate. And an interconnector. Further, the metal member for an electrochemical cell according to the present invention can be applied to a solid oxide electrochemical cell including a solid oxide electrolytic cell in addition to a fuel cell.

Modification 2
In the above embodiment, the first and second joining portions 311 and 312 are connected by the first and second connecting portions 313 and 314, but the present invention is not limited to this. The current collecting member 310 only needs to have the first and second joints 311 and 312 that are electrically connected, and the connecting means of the first and second joints 311 and 312 is not limited. For example, the first and second joints 311 and 312 may be connected by three or more connecting parts, or may be connected by one connecting part.

Modification 3
The first joining portion 311 may not have the first through hole 315. In this case, the side surface Sa3 of the first joining portion 311 is a side surface forming the outer edge of the first joining portion 311. Similarly, the second joint 312 may not have the second through-hole 316.

Modification 4
The current collecting member 310 may further include an oxide film. For example, it is preferable that the first bonding portion 311 is covered with an oxide film, and the covering layer covers the oxide film. For example, the first joint 311 is covered with a chromium oxide film. The chromium oxide film is composed of chromium oxide. The thickness of the chromium oxide film is not particularly limited, but may be, for example, 0.5 to 10 μm. In this case, the covering layer 317 is formed on the chromium oxide film.

Modification 5
The metal member for an electrochemical cell of the present invention is not limited to the current collector 310. For example, the metal member for an electrochemical cell of the present invention may be an end current collecting member for extracting a current from a fuel cell arranged at an end in the arrangement direction.

Modification 6
The configuration may be such that the thickness of the coating layer 317 in the first region R1 is greater than the thickness of the coating layer 317 in the second region R2. In this case, the thickness of the coating layer 317 in the first region R1 can be approximately 1.1 to 200 μm, and the thickness of the coating layer 317 in the second region R2 can be approximately 1.0 to 100 μm. The ratio of the thickness of the coating layer 317 in the first region R1 to the thickness of the coating layer 317 in the second region R2 can be about 1.1 to 50.

102: conductive bonding material 300: fuel cell 310: current collecting member 311: first bonding portion 317: coating layer 319: protrusion R1: first region R2: second region Sa1: first main surface Sa2: second Main surface Sa3: side surface Sa4: curved surface

Claims (6)

A metal member joined to the electrochemical cell,
A first main surface facing the electrochemical cell side, a second main surface opposite to the first main surface, and a main body having side surfaces;
With
The main body portion has a protrusion protruding from a corner formed by the second main surface and the side surface in a direction in which the second main surface faces, a curved surface connecting the first main surface and the side surface, Further having
Metal members for electrochemical cells.
Further comprising a coating layer covering the main body,
The side surface has a first region on the first main surface side and a second region on the second main surface side,
The surface roughness in the second region is larger than the surface roughness in the first region.
The metal member for an electrochemical cell according to claim 1.
A thickness of the coating layer in the second region is larger than a thickness of the coating layer in the first region;
The metal member for an electrochemical cell according to claim 1.
A thickness of the coating layer in the first region is larger than a thickness of the coating layer in the second region;
The metal member for an electrochemical cell according to claim 1.
The main body has a through hole,
The side surface constitutes an inner wall surface of the through hole,
The metal member for an electrochemical cell according to claim 1.
An electrochemical cell;
The metal member for an electrochemical cell according to any one of claims 1 to 5, wherein the first main surface is arranged to face the electrochemical cell.
A conductive bonding material for bonding the metal member to the electrochemical cell,
An electrochemical cell assembly comprising:

Images