JP2018206693A - Conductive member, electrochemical reaction unit and electrochemical reaction cell stack - Google Patents

Abstract

To suppress the warpage in the surface of a conductive member.SOLUTION: A conductive member comprises: a metal member containing Fe and Cr; an oxide coating layer disposed on a surface of the metal member and containing Cr oxide; and a coating layer disposed on a surface of the oxide coating layer on a side opposite to its surface opposed to the metal member and including Co oxide. The coating layer has a thickness of 10 μm or more and a porosity of 6.0% or more. In a section of the coating layer, the number of pores per unit area is 20/1000 μmor more.SELECTED DRAWING: Figure 8

Description

  The technique disclosed by this specification is related with an electroconductive member.

  A solid oxide fuel cell (hereinafter referred to as “SOFC”) is known as one type of fuel cell that generates electricity using an electrochemical reaction between hydrogen and oxygen. A fuel cell power generation unit (hereinafter referred to as “power generation unit”), which is a constituent unit of SOFC, includes a fuel cell single cell (hereinafter referred to as “single cell”). The single cell includes an electrolyte layer and an air electrode and a fuel electrode facing each other in a predetermined direction (hereinafter referred to as “first direction”) with the electrolyte layer interposed therebetween.

The power generation unit also includes a conductive interconnector disposed on one side of the first direction with respect to the single cell and formed of a metal (for example, ferritic stainless steel) containing Fe and Cr. The interconnector constitutes (compartments) a gas chamber facing the air electrode or the fuel electrode. On the surface of the interconnector, Cr contained in the interconnector reacts with oxygen in the air to form an oxide film layer containing Cr oxide (for example, Cr ₂ O ₃ (chromia)).

When Cr contained in the interconnector evaporates and adheres to the electrode of the single cell, a phenomenon called “Cr poisoning” in which the reaction rate at the electrode is reduced may occur, and the performance of the single cell may be reduced. In order to suppress such performance degradation of the single cell, a conductive coating containing Co oxide (for example, MnCo ₂ O ₄ ) on the surface of the interconnector (an oxide film layer formed on the surface of the interconnector) A structure in which a layer is formed is known (see, for example, Patent Document 1). In such a configuration, since the coating layer suppresses the transpiration of Cr from the interconnector, it is possible to suppress the deterioration of the performance of the single cell due to the Cr poisoning of the electrode. Hereinafter, the laminated body of an interconnector, an oxide film layer, and a coating layer is referred to as a conductive member.

JP 2011-99159 A

  Since the power generation unit becomes a high temperature during the power generation operation, undulation may occur in the oxide film layer in the conductive member with the operation of the power generation unit. When waviness occurs in the oxide film layer, the influence may cause waviness on the surface of the coating layer formed on the surface of the oxide film layer opposite to the surface facing the oxide film layer. When waviness occurs on the surface of the coating layer, for example, the adhesion between the conductive member and the sealing member disposed on the surface constituted by the coating layer is lowered, and as a result, the gas sealing property of the gas chamber is reduced. May decrease and the performance of the power generation unit may decrease.

 Note that such a problem is that the conductivity of the electrolytic cell unit, which is a constituent unit of a solid oxide electrolytic cell (hereinafter also referred to as “SOEC”), which generates hydrogen using an electrolysis reaction of water. This is a problem common to sex members. In the present specification, the fuel cell power generation unit and the electrolysis cell unit are collectively referred to as an electrochemical reaction unit. Such a problem is not limited to SOFC and SOEC, but is common to other types of electrochemical reaction units. Furthermore, such a problem is not limited to the conductive member constituting the electrochemical reaction unit, but a metal member containing Fe and Cr, and an oxide film layer disposed on the surface of the metal member and containing Cr oxide And a conductive member that is disposed on the surface of the oxide coating layer and includes a coating layer containing a Co oxide.

  In this specification, the technique which can solve the subject mentioned above is disclosed.

  The technology disclosed in the present specification can be realized as, for example, the following forms.

(1) A conductive member disclosed in the present specification includes a metal member containing Fe and Cr, an oxide film layer that is disposed on a surface of the metal member and includes Cr oxide, and the oxide film layer The conductive member is provided on a surface opposite to the surface facing the metal member, and includes a coating layer containing Co oxide, wherein the coating layer has a thickness of 10 μm or more, and the coating The porosity of the layer is 6.0% or more, and the number of pores per unit area in the cross section of the coating layer is 20/1000 μm ² or more. In this conductive member, the thickness of the coating layer is relatively large, the porosity of the coating layer is relatively high, and the number of pores per unit area in the cross section of the coating layer is relatively large. Therefore, according to the present conductive member, even when the oxide film layer is swelled by being heated during use, the influence causes the swell on the surface of the coating layer opposite to the surface facing the oxide film layer. Occurrence can be suppressed. Therefore, according to the present conductive member, for example, it is possible to suppress a decrease in adhesion between the conductive member and the sealing member disposed on the surface constituted by the coating layer, and a decrease in gas sealing performance. Can be suppressed.

(2) In the conductive member, the Co oxide included in the coating layer may have a spinel crystal structure. According to this conductive member, according to this conductive member, further growth of the oxide film layer can be effectively suppressed by the coating layer, and diffusion of Cr contained in the metal member can be effectively suppressed. Can be suppressed.

(3) In the conductive member, the covering layer may have a porosity of 40% or less. According to this conductive member, while ensuring the growth suppression function of the oxide film layer by the coating layer and the Cr diffusion suppression function from the metal member, the oxide film layer in the coating layer is affected by the swell generated in the oxide film layer. It is possible to suppress the occurrence of waviness on the surface opposite to the facing surface.

(4) The electrochemical reaction unit disclosed in this specification includes an electrochemical reaction unit cell including an electrolyte layer and an air electrode and a fuel electrode facing each other in a first direction with the electrolyte layer interposed therebetween, and the electric reaction unit cell. The said electroconductive member arrange | positioned with respect to a chemical reaction single cell at the one side of the said 1st direction, and the sealing member arrange | positioned on the surface comprised by the said coating layer in the said electroconductive member are provided. According to the present electrochemical reaction unit, it is possible to suppress a decrease in adhesion between the conductive member and the sealing member disposed on the surface constituted by the coating layer, resulting from a decrease in gas sealing performance. Performance degradation can be suppressed.

(5) In the electrochemical reaction unit, the electrochemical reaction single cell may be a fuel cell single cell. According to the present electrochemical reaction unit, it is possible to suppress a decrease in adhesion between the conductive member and the sealing member disposed on the surface constituted by the coating layer, resulting from a decrease in gas sealing performance. A decrease in power generation performance can be suppressed.

  The technology disclosed in the present specification can be realized in various forms. For example, a conductive member, a conductive member, and an electrochemical reaction single cell (fuel cell single cell or electrolytic single cell) Reaction unit (fuel cell power generation unit or electrolysis cell unit), electrochemical reaction cell stack (fuel cell stack or electrolysis cell stack) comprising a plurality of electrochemical reaction units, a manufacturing method thereof, etc. It is possible.

1 is a perspective view showing an external configuration of a fuel cell stack 100 in an embodiment. It is explanatory drawing which shows the XZ cross-section structure of the fuel cell stack 100 in the position of II-II of FIG. FIG. 3 is an explanatory diagram showing a YZ cross-sectional configuration of a fuel cell stack 100 at a position of III-III in FIG. 1. It is explanatory drawing which shows XZ cross-section structure of the two electric power generation units 102 adjacent to each other in the same position as the cross section shown in FIG. It is explanatory drawing which shows the YZ cross-section structure of the two electric power generation units 102 adjacent to each other in the same position as the cross section shown in FIG. FIG. 5 is an explanatory diagram showing an XY cross-sectional configuration of a power generation unit at a position of VI-VI in FIG. 4. It is explanatory drawing which shows XY cross-section structure of the electric power generation unit 102 in the position of VII-VII of FIG. It is explanatory drawing which shows notionally the detailed structure of the coating layer 196 which comprises the electric power generation unit 102 of this embodiment. It is explanatory drawing which shows notionally the detailed structure of the coating layer 196 which comprises the power generation unit 102X of a comparative example. It is explanatory drawing which shows a performance evaluation result.

A. Embodiment:
A-1. Constitution:
(Configuration of fuel cell stack 100)
FIG. 1 is a perspective view showing an external configuration of the fuel cell stack 100 in the embodiment, and FIG. 2 is an XZ cross section of the fuel cell stack 100 at a position II-II in FIG. 1 (and FIGS. 6 and 7 described later). FIG. 3 is an explanatory diagram showing a YZ cross-sectional configuration of the fuel cell stack 100 at the position of III-III in FIG. 1 (and FIGS. 6 and 7 described later). In each figure, XYZ axes orthogonal to each other for specifying the direction are shown. In this specification, for the sake of convenience, the positive direction of the Z axis is referred to as the upward direction, and the negative direction of the Z axis is referred to as the downward direction. However, the fuel cell stack 100 is actually different from such an orientation. It may be installed. The same applies to FIG.

  The fuel cell stack 100 includes a plurality (seven in this embodiment) of fuel cell power generation units (hereinafter simply referred to as “power generation units”) 102 and a pair of end plates 104 and 106. The seven power generation units 102 are arranged side by side in a predetermined arrangement direction (vertical direction in the present embodiment). The pair of end plates 104 and 106 are arranged so as to sandwich an assembly composed of seven power generation units 102 from above and below. The arrangement direction (vertical direction) corresponds to the first direction in the claims.

  A plurality of (eight in the present embodiment) holes penetrating in the vertical direction are formed in the peripheral portion around the Z direction of each layer (power generation unit 102, end plates 104, 106) constituting the fuel cell stack 100. The holes formed in each layer and corresponding to each other communicate with each other in the vertical direction to form a communication hole 108 extending in the vertical direction from one end plate 104 to the other end plate 106. In the following description, the holes formed in each layer of the fuel cell stack 100 to form the communication holes 108 may also be referred to as communication holes 108.

  Bolts 22 extending in the vertical direction are inserted into the communication holes 108, and the fuel cell stack 100 is fastened by the bolts 22 and nuts 24 fitted on both sides of the bolts 22. 2 and 3, between the nut 24 fitted on one side (upper side) of the bolt 22 and the upper surface of the end plate 104 constituting the upper end of the fuel cell stack 100, and the bolt An insulating sheet 26 is interposed between the nut 24 fitted on the other side (lower side) of 22 and the lower surface of the end plate 106 constituting the lower end of the fuel cell stack 100. However, in a place where a gas passage member 27 described later is provided, an insulating sheet disposed between the nut 24 and the surface of the end plate 106 on the upper and lower sides of the gas passage member 27 and the gas passage member 27, respectively. 26 is interposed. The insulating sheet 26 is made of, for example, a mica sheet, a ceramic fiber sheet, a ceramic powder sheet, a glass sheet, a glass ceramic composite agent, or the like.

  The outer diameter of the shaft portion of each bolt 22 is smaller than the inner diameter of each communication hole 108. Therefore, a space is secured between the outer peripheral surface of the shaft portion of each bolt 22 and the inner peripheral surface of each communication hole 108. As shown in FIGS. 1 and 2, the fuel cell stack 100 is located near the midpoint of one side (the X-axis positive direction side of two sides parallel to the Y-axis) on the outer periphery around the Z-direction. The space formed by the bolt 22 (bolt 22A) and the communication hole 108 through which the bolt 22A is inserted is introduced with the oxidant gas OG from the outside of the fuel cell stack 100, and the oxidant gas OG is generated by each power generation. It functions as an oxidant gas introduction manifold 161 that is a gas flow path to be supplied to the unit 102, and is the midpoint of the side opposite to the side (X-axis negative direction side of two sides parallel to the Y-axis) The space formed by the bolts 22 (bolts 22B) located in the vicinity and the communication holes 108 through which the bolts 22B are inserted contains the oxidant off-gas OOG that is the gas discharged from the air chamber 166 of each power generation unit 102. Burning Functions as the oxidizing gas discharging manifold 162 for discharging to the outside of the cell stack 100. In the present embodiment, for example, air is used as the oxidant gas OG.

  Further, as shown in FIGS. 1 and 3, the vicinity of the midpoint of one side (the side on the Y axis positive direction side of two sides parallel to the X axis) on the outer periphery of the fuel cell stack 100 around the Z direction The space formed by the bolt 22 (bolt 22D) positioned at the position and the communication hole 108 through which the bolt 22D is inserted is introduced with the fuel gas FG from the outside of the fuel cell stack 100, and the fuel gas FG is generated by each power generation. Bolt 22 that functions as a fuel gas introduction manifold 171 to be supplied to the unit 102 and is located in the vicinity of the midpoint of the opposite side (the side on the Y axis negative direction side of the two sides parallel to the X axis). The space formed by the (bolt 22E) and the communication hole 108 through which the bolt 22E is inserted is a fuel cell stack 1 that uses the fuel off-gas FOG that is a gas discharged from the fuel chamber 176 of each power generation unit 102 as the fuel cell stack 1 Functions as a fuel gas exhaust manifold 172 for discharging to the outside of the 0. In the present embodiment, as the fuel gas FG, for example, hydrogen-rich gas obtained by reforming city gas is used.

  The fuel cell stack 100 is provided with four gas passage members 27. Each gas passage member 27 has a hollow cylindrical main body portion 28 and a hollow cylindrical branch portion 29 branched from the side surface of the main body portion 28. The hole of the branch part 29 communicates with the hole of the main body part 28. A gas pipe (not shown) is connected to the branch portion 29 of each gas passage member 27. Further, as shown in FIG. 2, the hole of the main body portion 28 of the gas passage member 27 disposed at the position of the bolt 22 </ b> A forming the oxidant gas introduction manifold 161 communicates with the oxidant gas introduction manifold 161. The hole of the main body portion 28 of the gas passage member 27 disposed at the position of the bolt 22 </ b> B that forms the oxidant gas discharge manifold 162 communicates with the oxidant gas discharge manifold 162. Further, as shown in FIG. 3, the hole of the main body portion 28 of the gas passage member 27 arranged at the position of the bolt 22D forming the fuel gas introduction manifold 171 communicates with the fuel gas introduction manifold 171 and the fuel gas The hole of the main body portion 28 of the gas passage member 27 disposed at the position of the bolt 22 </ b> E forming the discharge manifold 172 communicates with the fuel gas discharge manifold 172.

(Configuration of end plates 104 and 106)
The pair of end plates 104 and 106 are substantially rectangular flat plate-shaped conductive members, and are formed of, for example, stainless steel. One end plate 104 is disposed on the upper side of the power generation unit 102 located on the uppermost side, and the other end plate 106 is disposed on the lower side of the power generation unit 102 located on the lowermost side. A plurality of power generation units 102 are held in a pressed state by a pair of end plates 104 and 106. The upper end plate 104 functions as a positive output terminal of the fuel cell stack 100, and the lower end plate 106 functions as a negative output terminal of the fuel cell stack 100.

(Configuration of power generation unit 102)
4 is an explanatory diagram showing an XZ cross-sectional configuration of two power generation units 102 adjacent to each other at the same position as the cross section shown in FIG. 2, and FIG. 5 is adjacent to each other at the same position as the cross section shown in FIG. It is explanatory drawing which shows the YZ cross-section structure of the two electric power generation units. In the upper part of FIG. 5, an enlarged YZ cross-sectional configuration of a part of the power generation unit 102 is shown. 6 is an explanatory diagram showing the XY cross-sectional configuration of the power generation unit 102 at the position VI-VI in FIG. 4, and FIG. 7 shows the XY cross-sectional configuration of the power generation unit 102 at the position VII-VII in FIG. It is explanatory drawing shown.

  As shown in FIGS. 4 and 5, the power generation unit 102 includes a single cell 110, a separator 120, an air electrode side frame 130, an air electrode side current collector 134, a fuel electrode side frame 140, and a fuel electrode side. A current collector 144 and a pair of interconnectors 150 constituting the uppermost layer and the lowermost layer of the power generation unit 102 are provided. The separator 120, the air electrode side frame 130, the fuel electrode side frame 140, and the periphery of the interconnector 150 around the Z direction are formed with holes corresponding to the communication holes 108 through which the bolts 22 are inserted.

  The interconnector 150 is a substantially rectangular flat plate-shaped conductive member, and is formed of a metal (for example, ferritic stainless steel) containing Fe and Cr. The interconnector 150 ensures electrical continuity between the power generation units 102 and prevents reaction gas from being mixed between the power generation units 102. In the present embodiment, when two power generation units 102 are arranged adjacent to each other, one interconnector 150 is shared by two adjacent power generation units 102. That is, the upper interconnector 150 in a power generation unit 102 is the same member as the lower interconnector 150 in another power generation unit 102 adjacent to the upper side of the power generation unit 102. Further, since the fuel cell stack 100 includes the pair of end plates 104 and 106, the power generation unit 102 located at the top in the fuel cell stack 100 does not include the upper interconnector 150 and is located at the bottom. The power generation unit 102 does not include the lower interconnector 150 (see FIGS. 2 and 3).

  The single cell 110 includes an electrolyte layer 112, a fuel electrode (anode) 116 disposed on one side (lower side) of the electrolyte layer 112 in the vertical direction (first direction), and the other side of the electrolyte layer 112 in the vertical direction. An air electrode (cathode) 114 disposed on the (upper side) and an intermediate layer 180 disposed between the electrolyte layer 112 and the air electrode 114 are provided. The single cell 110 of this embodiment is a fuel electrode-supported single cell that supports the other layers (the electrolyte layer 112, the air electrode 114, and the intermediate layer 180) constituting the single cell 110 with the fuel electrode 116.

  The electrolyte layer 112 is a substantially rectangular flat plate member as viewed in the Z direction, and is a dense layer. The electrolyte layer 112 is formed of a solid oxide such as YSZ (yttria stabilized zirconia), ScSZ (scandia stabilized zirconia), SDC (samarium doped ceria), GDC (gadolinium doped ceria), perovskite oxide, and the like. Yes. That is, the single cell 110 (power generation unit 102) of the present embodiment is a solid oxide fuel cell (SOFC) that uses a solid oxide as an electrolyte.

  The air electrode 114 is a substantially rectangular flat plate-shaped member smaller than the electrolyte layer 112 when viewed in the Z direction, and is a porous layer. The air electrode 114 is made of, for example, a perovskite oxide (for example, LSCF (lanthanum strontium cobalt iron oxide), LSM (lanthanum strontium manganese oxide), LNF (lanthanum nickel iron)).

  The fuel electrode 116 is a substantially rectangular flat plate member having substantially the same size as the electrolyte layer 112 when viewed in the Z direction, and is a porous layer. The fuel electrode 116 is formed of, for example, a cermet made of Ni and oxide ion conductive ceramic particles (for example, YSZ).

The intermediate layer 180 is a substantially rectangular flat plate-shaped member, and is formed so as to include GDC (gadolinium-doped ceria). The intermediate layer 180 indicates that an element (for example, Sr) diffused from the air electrode 114 reacts with an element (for example, Zr) contained in the electrolyte layer 112 to generate a high-resistance material (for example, SrZrO ₃ ). Suppress.

  The separator 120 is a frame-like member in which a substantially rectangular hole 121 penetrating in the vertical direction is formed near the center, and is made of, for example, metal. The peripheral part of the hole 121 in the separator 120 is opposed to the peripheral part of the surface of the electrolyte layer 112 on the air electrode 114 side. The separator 120 is bonded to the electrolyte layer 112 (single cell 110) by a bonding portion 124 formed of a brazing material (for example, Ag brazing) disposed in the facing portion. The separator 120 divides the air chamber 166 facing the air electrode 114 and the fuel chamber 176 facing the fuel electrode 116, and gas leaks from one electrode side to the other electrode side in the peripheral portion of the single cell 110. It is suppressed.

 As shown in FIGS. 4 to 6, the air electrode side frame 130 is a frame-like member in which a substantially rectangular hole 131 penetrating in the vertical direction is formed near the center, and is formed of an insulator such as mica, for example. ing. The hole 131 of the air electrode side frame 130 forms an air chamber 166 that faces the air electrode 114. The air electrode side frame 130 is in contact with the peripheral edge of the surface of the separator 120 opposite to the side facing the electrolyte layer 112 and the peripheral edge of the surface of the interconnector 150 facing the air electrode 114. , It functions as a seal member that ensures gas sealability between them (that is, gas sealability of the air chamber 166). The pair of interconnectors 150 included in the power generation unit 102 is electrically insulated by the air electrode side frame 130. The air electrode side frame 130 has an oxidant gas supply communication hole 132 communicating the oxidant gas introduction manifold 161 and the air chamber 166, and an oxidant gas communicating the air chamber 166 and the oxidant gas discharge manifold 162. A discharge communication hole 133 is formed.

  As shown in FIGS. 4, 5, and 7, the fuel electrode side frame 140 is a frame-like member in which a substantially rectangular hole 141 penetrating in the vertical direction is formed near the center, and is formed of, for example, metal. . The hole 141 of the fuel electrode side frame 140 forms a fuel chamber 176 that faces the fuel electrode 116. The fuel electrode side frame 140 is in contact with the peripheral portion of the surface of the separator 120 facing the electrolyte layer 112 and the peripheral portion of the surface of the interconnector 150 facing the fuel electrode 116. Further, the fuel electrode side frame 140 has a fuel gas supply communication hole 142 that connects the fuel gas introduction manifold 171 and the fuel chamber 176, and a fuel gas discharge communication hole 143 that connects the fuel chamber 176 and the fuel gas discharge manifold 172. And are formed.

  As shown in FIGS. 4, 5 and 7, the fuel electrode side current collector 144 is disposed in the fuel chamber 176. The fuel electrode side current collector 144 includes an interconnector facing portion 146, an electrode facing portion 145, and a connecting portion 147 that connects the electrode facing portion 145 and the interconnector facing portion 146. For example, nickel or a nickel alloy It is made of stainless steel or the like. The electrode facing portion 145 is in contact with the surface of the fuel electrode 116 on the side opposite to the side facing the electrolyte layer 112, and the interconnector facing portion 146 is on the surface of the interconnector 150 on the side facing the fuel electrode 116. In contact. However, as described above, since the lowermost power generation unit 102 in the fuel cell stack 100 does not include the lower interconnector 150, the interconnector facing portion 146 in the power generation unit 102 has a lower end plate. 106 is in contact. Since the fuel electrode side current collector 144 has such a configuration, the fuel electrode 116 and the interconnector 150 (or the end plate 106) are electrically connected. Note that a spacer 149 made of, for example, mica is disposed between the electrode facing portion 145 and the interconnector facing portion 146. Therefore, the fuel electrode side current collector 144 follows the deformation of the power generation unit 102 due to the temperature cycle and the reaction gas pressure fluctuation, and the fuel electrode 116 and the interconnector 150 (or the end plate 106) via the fuel electrode side current collector 144. The electrical connection with is maintained well.

  As shown in FIGS. 4 to 6, the air electrode side current collector 134 is disposed in the air chamber 166. The air electrode side current collector 134 is composed of a plurality of substantially square columnar current collector elements 135, and is formed of a metal containing Fe and Cr (for example, ferritic stainless steel). The air electrode side current collector 134 is in contact with the surface of the air electrode 114 opposite to the side facing the electrolyte layer 112 and the surface of the interconnector 150 facing the air electrode 114. However, as described above, since the power generation unit 102 located at the top in the fuel cell stack 100 does not include the upper interconnector 150, the air electrode side current collector 134 in the power generation unit 102 includes the upper end plate. 104 is in contact. Since the air electrode side current collector 134 has such a configuration, the air electrode 114 and the interconnector 150 (or the end plate 104) are electrically connected.

  As shown in FIGS. 4 and 5, in the present embodiment, the air electrode side current collector 134 (current collector element 135) and the interconnector 150 are formed as an integral member. That is, of the integrated member (hereinafter referred to as “metal member 190”), a flat plate-shaped portion orthogonal to the vertical direction (Z-axis direction) functions as the interconnector 150, and the flat electrode portion extends from the flat electrode portion to the air electrode. A plurality of current collector elements 135 formed so as to project toward 114 function as the air electrode side current collector 134.

As shown in FIG. 5, an oxide film layer 194 containing Cr oxide (for example, Cr ₂ O ₃ (chromia)) is formed on the surface of the metal member 190. The oxide film layer 194 is formed by the reaction of Cr contained in the metal member 190 with oxygen in the atmosphere.

Further, as shown in FIGS. 4 and 5, a conductive coating layer 196 containing Co oxide is disposed on the surface of the oxide film layer 194 opposite to the surface facing the metal member 190. . The coating layer 196 has a spinel crystal structure and is, for example, a Co oxide containing at least one element of Cr, Mn, Fe, Ni, Cu, and Zn (for example, CrCo ₂ O ₄ , MnCo ₂ O _4). FeCo ₂ O ₄ , NiCo ₂ O ₄ , CuCo ₂ O ₄ , ZnCo ₂ O ₄ , ZnMnCoO _4, etc.). Since the coating layer 196 suppresses the permeation of oxygen, the growth of the oxide film layer 194 having a high electrical resistance can be suppressed. As a result, the electrical resistance of the conductive member 200 increases (that is, the performance of the power generation unit 102). Reduction) can be suppressed. Moreover, since the coating layer 196 suppresses the transpiration of Cr from the metal member 190, the generation of Cr poisoning of the electrode (for example, the air electrode 114) of the single cell 110 can be suppressed. The performance degradation can be suppressed.

As shown in FIGS. 4 and 5, the air electrode 114 and the air electrode side current collector 134 (current collector element 135) (covered by the oxide film layer 194 and the coating layer 196) are electrically connected to each other. 138 to be joined. The bonding layer 138 includes, for example, an oxide having a spinel crystal structure (for example, Mn _1.5 Co _1.5 O ₄ , MnCo ₂ O ₄ , ZnCo ₂ O ₄ , ZnMn ₂ O ₄ , ZnMnCoO ₄ , CuMn ₂ O). ₄ ). The air electrode 114 and the air electrode side current collector 134 are electrically connected by the bonding layer 138. Although it has been described above that the air electrode side current collector 134 is in contact with the surface of the air electrode 114, the bonding layer 138 is precisely between the air electrode side current collector 134 and the air electrode 114. Intervene.

  In the following description, metal member 190 (integrated member of interconnector 150 and air electrode side current collector 134), oxide film layer 194 formed on the surface of metal member 190, and metal member in oxide film layer 194 The covering layer 196 formed on the surface opposite to the surface facing 190 is collectively referred to as the conductive member 200. The conductive member 200 is electrically connected to the air electrode 114 via the bonding layer 138, and is electrically connected to the fuel electrode 116 via the fuel electrode side current collector 144.

A-2. Operation of the fuel cell stack 100:
As shown in FIGS. 2 and 4, the oxidant gas OG is supplied through a gas pipe (not shown) connected to the branch portion 29 of the gas passage member 27 provided at the position of the oxidant gas introduction manifold 161. Then, the oxidant gas OG is supplied to the oxidant gas introduction manifold 161 through the branch portion 29 of the gas passage member 27 and the hole of the main body portion 28, and the oxidant gas introduction manifold 161 oxidizes each power generation unit 102. It is supplied to the air chamber 166 through the agent gas supply communication hole 132. Further, as shown in FIGS. 3 and 5, the fuel gas FG is supplied through a gas pipe (not shown) connected to the branch portion 29 of the gas passage member 27 provided at the position of the fuel gas introduction manifold 171. Then, the fuel gas FG is supplied to the fuel gas introduction manifold 171 through the branch portion 29 of the gas passage member 27 and the hole of the main body portion 28, and the fuel gas supply communication of each power generation unit 102 from the fuel gas introduction manifold 171. The fuel chamber 176 is supplied through the hole 142.

  When the oxidant gas OG is supplied to the air chamber 166 of each power generation unit 102 and the fuel gas FG is supplied to the fuel chamber 176, power is generated by an electrochemical reaction between the oxidant gas OG and the fuel gas FG in the single cell 110. Is called. This power generation reaction is an exothermic reaction. In each power generation unit 102, the air electrode 114 of the single cell 110 is electrically connected to the conductive member 200 (an assembly of the metal member 190, the oxide film layer 194, and the coating layer 196) via the bonding layer 138, and the fuel electrode. 116 is electrically connected to the conductive member 200 via the fuel electrode side current collector 144. That is, the plurality of power generation units 102 included in the fuel cell stack 100 are electrically connected in series. Therefore, electrical energy generated in each power generation unit 102 is taken out from the end plates 104 and 106 that function as output terminals of the fuel cell stack 100. Since SOFC generates power at a relatively high temperature (for example, 700 ° C. to 1000 ° C.), the fuel cell stack 100 is heated by a heater (after the start-up until the high temperature can be maintained by the heat generated by the power generation. (Not shown).

  The oxidant off-gas OOG discharged from the air chamber 166 of each power generation unit 102 is discharged to the oxidant gas discharge manifold 162 via the oxidant gas discharge communication hole 133 as shown in FIGS. The fuel cell stack 100 is connected to the branch portion 29 via a gas pipe (not shown) through the holes of the main body portion 28 and the branch portion 29 of the gas passage member 27 provided at the position of the agent gas discharge manifold 162. Is discharged outside. Further, as shown in FIGS. 3 and 5, the fuel off-gas FOG discharged from the fuel chamber 176 of each power generation unit 102 is discharged to the fuel gas discharge manifold 172 via the fuel gas discharge communication hole 143, and further to the fuel gas. The gas passage member 27 provided at the position of the discharge manifold 172 passes through the body portion 28 and the branch portion 29 and passes through a gas pipe (not shown) connected to the branch portion 29 to the outside of the fuel cell stack 100. Discharged.

A-3. Detailed configuration of coating layer 196:
FIG. 8 is an explanatory diagram conceptually showing the detailed structure of the covering layer 196 that constitutes the power generation unit 102 of the present embodiment. A column A in FIG. 8 shows a YZ cross-sectional configuration of a part of the power generation unit 102 in the initial state (X1 portion in FIG. 5), and a column B in FIG. 8 shows after long-term durability (after power generation operation). A YZ cross-sectional configuration of the same portion of the power generation unit 102 is shown.

In the power generation unit 102 of the present embodiment, the thickness T1 of the coating layer 196 is 10 μm or more and is relatively thick. Moreover, the porosity of the coating layer 196 is 6.0% or more, and there are relatively many pores VO in the coating layer 196. Further, the number of pores per unit area in the cross section of the coating layer 196 is 20/1000 μm ² or more, and the deviation of the pores VO in the coating layer 196 is relatively small (that is, the dispersibility of the pores VO in the coating layer 196 is small). Relatively high). The coating layer 196 having such a configuration is manufactured, for example, by controlling the rate of temperature increase when the coating layer 196 is formed on the metal member 190 by heat treatment in a range of 1 ° C./min to 6 ° C./min. be able to.

  In the power generation unit 102 of the present embodiment, since the coating layer 196 has the above-described configuration, as described below, the surface of the coating layer 196 opposite to the surface facing the oxide coating layer 194 (hereinafter, It is possible to suppress the occurrence of undulation in the “first surface F1”), and as a result, it is possible to suppress the performance deterioration of the power generation unit 102 due to the deterioration of the gas sealability of the air chamber 166.

FIG. 9 is an explanatory diagram conceptually showing the detailed structure of the coating layer 196 constituting the power generation unit 102X of the comparative example. A column A in FIG. 9 shows a YZ cross-sectional configuration of a part of the power generation unit 102X in an initial state (a portion corresponding to the portion shown in the column A in FIG. 8), and a column B in FIG. A YZ cross-sectional configuration of the same portion of the power generation unit 102X after long-term durability (after power generation operation) is shown. As shown in the column A of FIG. 9, in the power generation unit 102X of the comparative example, the thickness T1 of the coating layer 196 is relatively thin (for example, less than 10 μm), and the porosity of the coating layer 196 is relatively low (for example, , Less than 6.0%), and the number of pores per unit area in the cross section of the coating layer 196 is relatively small (for example, less than 20/1000 μm ² ).

  Here, the power generation unit 102 (102X) becomes high temperature during the power generation operation. Therefore, as shown in the B column of FIG. 9, undulation may occur in the oxide film layer 194 in the conductive member 200 as the power generation unit 102 (102X) is used (power generation operation). As described above, in the power generation unit 102X of the comparative example, the thickness T1 of the covering layer 196 is relatively thin, the porosity of the covering layer 196 is relatively low, and the number of pores per unit area in the cross section of the covering layer 196 is compared. Less. Therefore, when waviness occurs in the oxide film layer 194, the waviness cannot be effectively absorbed by the coating layer 196, and the surface of the coating layer 196 opposite to the surface facing the oxide film layer 194 (first surface) The surface F1) of the substrate is further warped. Therefore, the adhesion between the surface (first surface F1) constituted by the covering layer 196 in the conductive member 200 and the air electrode side frame 130 as a seal member disposed on the first surface F1. Decreases, and the gas sealing performance of the air chamber 166 decreases. As a result, leakage of the oxidant gas OG from the air chamber 166 to the outside may occur between the first surface F1 of the coating layer 196 and the air electrode side frame 130, and the performance of the power generation unit 102X may be deteriorated. is there.

  On the other hand, in the power generation unit 102 of the present embodiment, the thickness T1 of the coating layer 196 is relatively thick, the porosity of the coating layer 196 is relatively high, and the number of pores per unit area in the cross section of the coating layer 196 is compared. Many. Therefore, as shown in the B column of FIG. 8, even if undulation occurs in the oxide film layer 194 with use of the power generation unit 102 (power generation operation), the undulation can be effectively absorbed by the coating layer 196, It is possible to suppress the occurrence of waviness on the surface of the coating layer 196 opposite to the surface facing the oxide film layer 194 (first surface F1). Therefore, the adhesion between the surface (first surface F1) constituted by the covering layer 196 in the conductive member 200 and the air electrode side frame 130 as a seal member disposed on the first surface F1. Is ensured, and the deterioration of the gas sealing property of the air chamber 166 can be suppressed. As a result, leakage of the oxidant gas OG from the air chamber 166 to the outside can be suppressed between the first surface F1 of the coating layer 196 and the air electrode side frame 130, and the performance of the power generation unit 102 can be suppressed. Can be suppressed.

As described above, the conductive member 200 constituting the power generation unit 102 of the present embodiment is disposed on the surface of the metal member 190 containing Fe and Cr, and the oxidation containing Cr oxide. The coating layer 194 includes a coating layer 196 that is disposed on the surface of the oxide coating layer 194 opposite to the surface facing the metal member 190, and includes a Co oxide. The coating layer 196 has a thickness of 10 μm or more. The porosity of the coating layer 196 is 6.0% or more, and the number of pores per unit area in the cross section of the coating layer 196 is 20/1000 μm ² or more. Therefore, according to the conductive member 200 constituting the power generation unit 102 of the present embodiment, even if the oxide film layer 194 swells due to the use of the power generation unit 102 (power generation operation), the oxidation in the coating layer 196 is caused by the influence thereof. Waviness can be suppressed from occurring on the surface opposite to the surface facing the coating layer 194 (first surface F1). Therefore, according to the conductive member 200 constituting the power generation unit 102 of the present embodiment, the seal member (air electrode) disposed on the surface (first surface F1) formed by the coating layer 196 in the conductive member 200. The lowering of the adhesiveness with the side frame 130) can be suppressed, and the performance deterioration of the power generation unit 102 due to the lowering of the gas sealing property of the air chamber 166 can be suppressed.

  Note that the Co oxide included in the coating layer 196 preferably has a spinel crystal structure. According to such a configuration, the coating layer 196 can effectively suppress further growth of the oxide film layer 194 and can also effectively suppress diffusion of Cr contained in the metal member 190. . In order to suppress the growth of the oxide film layer 194 by the coating layer 196, the Co oxide contained in the coating layer 196 further preferably contains at least one element of Cr, Mn, Fe, Ni, Cu, and Zn. .

  Further, the porosity of the covering layer 196 is preferably 40% or less. According to such a configuration, the coating layer 196 is affected by the undulation generated in the oxide coating layer 194 while ensuring the growth suppression function of the oxide coating layer 194 by the coating layer 196 and the Cr diffusion suppression function from the metal member 190. It is possible to suppress the occurrence of waviness on the surface opposite to the surface facing the oxide film layer 194 (first surface F1). Further, the porosity of the coating layer 196 is more preferably 20% or less. According to such a configuration, the function of suppressing the growth of the oxide film layer 194 by the coating layer 196 and the function of suppressing the Cr diffusion from the metal member 190 are more effectively secured, while the first surface F1 of the coating layer 196 is formed on the first surface F1. Swelling can be suppressed.

In order to suppress an increase in the resistance of the coating layer 196, the thickness of the coating layer 196 is preferably 20 μm or less (more preferably 15 μm or less), and the thickness per unit area in the cross section of the coating layer 196 is pore number, (and more preferably an average at 55/1000 .mu.m ² or less) and an average of 60 pieces / 1000 .mu.m ² or less.

A-4. Performance evaluation:
As described above, each power generation unit 102 constituting the fuel cell stack 100 of the present embodiment is characterized by the configuration of the coating layer 196. Hereinafter, the performance evaluation performed regarding the structure of the coating layer 196 is demonstrated. FIG. 10 is an explanatory diagram showing the performance evaluation results.

As shown in FIG. 10, three samples (samples S1 to S3) of the power generation unit 102 were used for this performance evaluation. Each sample has a different configuration (thickness, porosity, number of pores per unit area in cross section) of the coating layer 196. Note that the number of pores per unit area in a cross section, determine the number of pores per cross-sectional area of 1 [mu] m ^2, in terms of number of pores per cross-sectional area of 1000 .mu.m ² it 1000 times to.

Further, as shown in FIG. 10, regarding the porosity and the number of pores, the covering layer 196 has an upper layer portion (portion closest to the oxide coating layer 194), a middle layer portion, a lower layer portion (on the air electrode side frame 130) in the thickness direction. The value of each part was calculated. In each sample, the number of pores was less varied in each part (upper layer part, middle layer part, lower layer part). That is, in sample S1, the standard deviation of the number of pores of each part (upper layer part, middle layer part, lower layer part) was 12.9 (the average value was 50.8 / 1000 μm ² ). Similarly, in sample S2, the standard deviation was 7.1 (average value was 35.5 / 1000 μm ² ), and in sample S3, the standard deviation was 5.7 (average value was 30.0). Piece / 1000 μm ² ). Therefore, it can be said that each sample in the present invention is evenly distributed in each part (upper layer part, middle layer part, lower layer part) without uneven pores.

  In this performance evaluation, each sample was heat-treated at 1000 ° C. for 200 hours, and then the height difference Δh of the first surface F1 (see FIG. 8) of the coating layer 196 was measured. This height difference Δh is specified as follows. That is, a cross-sectional image (field of view 100 μm) of the coating layer 196 is obtained, a boundary point between the coating layer 196 and the oxide film layer 194 at both ends of the field of view is specified, and a straight line connecting the two boundary points is used as a reference line . On the line representing the first surface F1 of the coating layer 196, the highest point is the point farthest from the reference line, the lowest point is the point closest to the reference line, and the distance from the reference line at the highest point The difference between the distance from the reference line at the lowest point and the height difference Δh. When the height difference Δh was 3.5 μm or more, the first surface F1 of the coating layer 196 was greatly swelled, and the gas sealability was likely to be deteriorated. Moreover, when the height difference Δh was less than 3.5 μm, the undulation of the first surface F1 of the coating layer 196 was small, and it was determined as acceptable (◯) because the gas sealing property was ensured.

  In this performance evaluation, in addition, in the cross-sectional image, the length L1 of the first surface F1 of the coating layer 196 and the length L2 of the surface of the oxide coating layer 194 on the side facing the coating layer 196 are set. The ratio of the length L1 to the length L2 (L1 / L2) was calculated as the surface length ratio C. The relatively large surface length ratio C means that the length L1 of the first surface F1 of the coating layer 196 is relatively long, that is, the degree of undulation of the first surface F1 of the coating layer 196 is relatively large. Means. On the other hand, the relatively small surface length ratio C indicates that the length L1 of the first surface F1 of the coating layer 196 is relatively short, that is, the degree of undulation of the first surface F1 of the coating layer 196 is compared. Means small.

As shown in FIG. 10, in the sample S3, the height difference Δh of the first surface F1 of the coating layer 196 was 3.75 μm, so it was determined to be rejected (x). In sample S3, the coating layer 196 has a relatively thin thickness T1 (less than 10 μm), a relatively low porosity (less than 6.0%), and a small number of pores per unit area ( (Average 30/1000 μm ² or less). Therefore, in the sample S3, it is considered that the undulation generated in the oxide film layer 194 due to the heat treatment cannot be effectively absorbed by the coating layer 196, and the undulation is generated in the first surface F1 of the coating layer 196. .

On the other hand, in samples S1 and S2, the height difference Δh of the first surface F1 of the coating layer 196 was 1.20 μm and 2.58 μm, respectively. In the samples S1 and S2, the configuration of the coating layer 196 is such that the thickness T1 is relatively thick (10 μm or more), the porosity is relatively high (6.0% or more), and the number of pores per unit area is often (and 20 or / 1000 .mu.m ² or more, the average is 30/1000 .mu.m ² greater) is configured. Therefore, in the samples S1 and S2, the undulation generated in the oxide film layer 194 by the heat treatment can be effectively absorbed by the coating layer 196, and the generation of the undulation on the first surface F1 of the coating layer 196 is suppressed. It is thought that it was made.

According to the performance evaluation described above, the thickness T1 of the coating layer 196 is 10 μm or more, the porosity of the coating layer 196 is 6.0% or more, and the number of pores per unit area in the cross section of the coating layer 196 is 20 / 1000 μm ² or more, even if waviness occurs in the oxide film layer 194, waviness occurs on the surface of the coating layer 196 opposite to the surface facing the oxide film layer 194 (first surface F 1). Occurrence can be suppressed, and deterioration in gas sealing performance can be suppressed by suppressing deterioration in adhesion between the sealing member (air electrode side frame 130) disposed on the first surface F1. It was confirmed that Note that the number of pores per unit area in the cross section of the coating layer 196 is more preferably an average of more than 30/1000 μm ² .

  As shown in FIG. 10, in the samples S1 and S2, the ratio of the length L1 of the first surface F1 of the coating layer 196 to the length L2 of the surface of the oxide coating layer 194 facing the coating layer 196 ( L1 / L2), the surface length ratio C was less than 89%. Therefore, if the surface length ratio C is less than 89%, it can be said that the occurrence of undulation on the first surface F1 of the coating layer 196 can be suppressed.

A-5. Method for analyzing coating layer 196:
A method for specifying the thickness T1 of the coating layer 196 is as follows. First, obtain an SEM image at a magnification of 1000 so that the boundary between the steel material (interconnector 150) and the coating layer 196 and the surface of the coating layer 196 (the surface on the air electrode side frame 130 side) fit within the same image. To do. Next, a virtual boundary line connecting both ends of the steel material in the SEM image is set, and a plurality of (for example, 10) virtual straight lines orthogonal to the virtual boundary line are set. On each virtual line, the distance between the intersection with the virtual boundary line and the intersection with the surface of the coating layer 196 is defined as the thickness of the coating layer 196 on the virtual line. The average value of the thickness of the coating layer 196 on each virtual straight line is defined as the final thickness T1 of the coating layer 196.

  Moreover, the specific method of the porosity of the coating layer 196 is as follows. First, an SEM image is acquired at a magnification of 1000 to 3000 so that the entire cross section of the coating layer 196 fits in the image, and the SEM image is binarized. When binarizing the SEM image, the binarization threshold value is adjusted so that the pore sizes match before and after binarization. Next, in the image after binarization, the total area of the covering layer 196 and the total area of the pores are calculated, and the total area of the pores / the total area of the covering layer 196 × 100 is calculated as the porosity of the covering layer 196. To do. As described above, in the present embodiment, the coating layer 196 is divided into the upper layer portion, the middle layer portion, and the lower layer portion in the thickness direction, and the porosity of each portion is calculated.

The method for specifying the number of pores per unit area in the cross section of the coating layer 196 is as follows. First, similarly to the method for specifying the porosity, an SEM image is acquired, and the SEM image is binarized. Next, in the binarized image, the area of the coating layer 196 is calculated and the number of pores is counted. The number of pores / the area of the coating layer 196 is defined as the number of pores per unit area in the cross section of the coating layer 196. Note that, as described above, in the present embodiment, the coating layer 196 is divided into three parts in the thickness direction: an upper layer part, a middle layer part, and a lower layer part, and the number of pores per unit area of each part is calculated. Moreover, in this embodiment, the number of pores per cross-sectional area of 1 μm ² was obtained and multiplied by 1000 to convert the number of pores per cross-sectional area of 1000 μm ² .

B. Variation:
The technology disclosed in the present specification is not limited to the above-described embodiment, and can be modified into various forms without departing from the gist thereof. For example, the following modifications are possible.

  The configuration of the single cell 110, the power generation unit 102, or the fuel cell stack 100 in the above embodiment is merely an example, and various modifications can be made. For example, in the above embodiment, the interconnector 150 and the air electrode side current collector 134 (current collector element 135) are an integral member (metal member 190). 134 may be a separate member. In that case, the present invention is also applicable to a conductive member composed of an interconnector 150 as a metal member, an oxide film layer 194, and a coating layer 196.

  In the above embodiment, the surface on the air electrode 114 side of the interconnector 150 is covered with the coating layer 196. However, the surface of the interconnector 150 is replaced with the surface on the air electrode 114 side or together with the surface on the air electrode 114 side. The surface of the connector 150 on the fuel electrode 116 side may be covered with the coating layer 196. In this case, if the configuration of the coating layer 196 is the same as that of the above-described embodiment, it is possible to suppress a decrease in gas sealability of the fuel chamber 176.

  In the above embodiment, the single cell 110 includes the intermediate layer 180, but the single cell 110 may not include the intermediate layer 180. In the above embodiment, the number of power generation units 102 included in the fuel cell stack 100 is merely an example, and the number of power generation units 102 is appropriately determined according to the output voltage required for the fuel cell stack 100 or the like.

  Further, the configuration of the coating layer 196 described in the above embodiment may be adopted in all the power generation units 102 included in the fuel cell stack 100, or only a part of the power generation units 102 included in the fuel cell stack 100. May be employed.

  In the above embodiment, the SOFC that generates electricity using the electrochemical reaction between hydrogen contained in the fuel gas and oxygen contained in the oxidant gas is targeted. The present invention can be similarly applied to an electrolytic cell unit that is a constituent unit of a solid oxide electrolytic cell (SOEC) that generates hydrogen by using hydrogen, and an electrolytic cell stack including a plurality of electrolytic cell units. The configuration of the electrolysis cell stack is well known as described in, for example, Japanese Patent Application Laid-Open No. 2006-81813, and therefore will not be described in detail here, but is roughly the same as the fuel cell stack 100 in the above-described embodiment. It is the composition. That is, the fuel cell stack 100 in the above-described embodiment may be read as an electrolytic cell stack, the power generation unit 102 may be read as an electrolytic cell unit, and the single cell 110 may be read as an electrolytic single cell. However, when the electrolysis cell stack is operated, a voltage is applied between the two electrodes so that the air electrode 114 is positive (anode) and the fuel electrode 116 is negative (cathode). Water vapor as a source gas is supplied. As a result, an electrolysis reaction of water occurs in each electrolysis cell unit, hydrogen gas is generated in the fuel chamber 176, and hydrogen is taken out of the electrolysis cell stack through the communication hole. Also in the electrolytic cell unit and the electrolytic cell stack having such a configuration, by employing the coating layer 196 having the above-described configuration, the surface of the coating layer 196 opposite to the surface facing the oxide film layer 194 (first surface) It is possible to suppress the occurrence of undulation on the surface F1), and it is possible to suppress the performance deterioration due to the deterioration of the gas sealing performance in the air chamber 166 and / or the fuel chamber 176.

 In the above embodiment, the solid oxide fuel cell (SOFC) has been described as an example. However, the present invention is applicable to other types of fuel cells (or electrolytic cells) such as a molten carbonate fuel cell (MCFC). Applicable. In addition, the present invention is not limited to a conductive member constituting an electrochemical reaction unit, but a metal member containing Fe and Cr, an oxide film layer disposed on the surface of the metal member and containing a Cr oxide, It is generally applicable to a conductive member that is disposed on the surface of an oxide film layer and includes a coating layer containing Co oxide.

22: Bolt 24: Nut 26: Insulating sheet 27: Gas passage member 28: Body portion 29: Branch portion 100: Fuel cell stack 102: Fuel cell power generation unit 104: End plate 106: End plate 108: Communication hole 110: Single cell 112: Electrolyte layer 114: Air electrode 116: Fuel electrode 120: Separator 121: Hole 124: Joint part 130: Air electrode side frame 131: Hole 132: Oxidant gas supply communication hole 133: Oxidant gas discharge communication hole 134: Air Polar side current collector 135: Current collector element 138: Bonding layer 140: Fuel electrode side frame 141: Hole 142: Fuel gas supply communication hole 143: Fuel gas discharge communication hole 144: Fuel electrode side current collector 145: Electrode facing Part 146: Interconnector facing part 147: Connection part 149: Spacer 50: Interconnector 161: Oxidant gas introduction manifold 162: Oxidant gas discharge manifold 166: Air chamber 171: Fuel gas introduction manifold 172: Fuel gas discharge manifold 176: Fuel chamber 180: Intermediate layer 190: Metal member 194: Oxide film Layer 196: Covering layer 200: Conductive member

Claims (6)

A metal member containing Fe and Cr;
An oxide film layer disposed on the surface of the metal member and containing Cr oxide;
A coating layer that is disposed on a surface opposite to the surface facing the metal member in the oxide coating layer and includes a Co oxide;
In a conductive member comprising:
The coating layer has a thickness of 10 μm or more,
The porosity of the coating layer is 6.0% or more,
The conductive member characterized in that the number of pores per unit area in the cross-section of the coating layer is 20/1000 μm ² or more. The conductive member according to claim 1,
The conductive member, wherein the Co oxide contained in the coating layer has a spinel crystal structure. In the conductive member according to claim 1 or 2,
The conductive member according to claim 1, wherein a porosity of the covering layer is 40% or less. An electrochemical reaction unit,
An electrochemical reaction unit cell including an electrolyte layer and an air electrode and a fuel electrode facing each other in a first direction across the electrolyte layer;
The conductive member according to any one of claims 1 to 3, which is disposed on one side of the first direction with respect to the electrochemical reaction single cell;
A sealing member disposed on a surface constituted by the coating layer in the conductive member;
An electrochemical reaction unit comprising: The electrochemical reaction unit according to claim 4,
The electrochemical reaction unit cell is a fuel cell unit cell, an electrochemical reaction unit. In an electrochemical reaction cell stack comprising a plurality of electrochemical reaction units arranged side by side in the first direction,
The electrochemical reaction cell stack according to claim 4, wherein at least one of the plurality of electrochemical reaction units is the electrochemical reaction unit according to claim 4.

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