JP6917182B2 - Conductive members, electrochemical reaction units, and electrochemical reaction cell stacks - Google Patents

Description

The techniques disclosed herein relate to conductive members.

A solid oxide fuel cell (hereinafter referred to as "SOFC") is known as one of the fuel cells that generate electricity by utilizing an electrochemical reaction between hydrogen and oxygen. The fuel cell power generation unit (hereinafter, referred to as “power generation unit”), which is a constituent unit of the SOFC, includes a fuel cell single cell (hereinafter, referred to as “single cell”) and a conductive current collecting member. The single cell includes an electrolyte layer and an air electrode and a fuel electrode that face each other in a predetermined direction (hereinafter, referred to as “first direction”) across the electrolyte layer. The current collector member is electrically connected to an air electrode or a fuel electrode constituting a single cell.

The current collecting member includes a metal member formed of a metal containing Fe and Cr (for example, ferritic stainless steel). When Cr contained in the metal member constituting the current collecting member reacts with oxygen in the air, an _{oxide film layer containing Cr oxide (for example, Cr 2} O ₃ (chromia)) is formed on the surface of the metal member. .. Since the oxide film layer containing Cr oxide has low oxygen permeability, it suppresses the oxidation of Fe, which is more unfavorable for metal members. On the other hand, since the oxide film layer containing Cr oxide has a high electric resistance, if the oxide film layer further grows, the electric resistance of the current collecting member may increase and the performance of the power generation unit may deteriorate.

Further, when Cr contained in the metal member constituting the current collecting member evaporates and adheres to the electrode of the single cell, a phenomenon called "Cr poisoning" in which the reaction rate at the electrode decreases occurs, and the single cell (power generation unit) ) Performance may deteriorate.

In order to suppress the deterioration of the performance of the power generation unit such as these, Co It is known that a coating layer containing an oxide (for example, MnCo ₂ O ₄ ) is formed (see, for example, Patent Document 1). In the current collector member having such a configuration, since the coating layer suppresses the permeation of oxygen, further growth of the oxide film layer is suppressed, and as a result, the electric resistance of the current collector member is increased (that is, the performance of the power generation unit is deteriorated). ) Can be suppressed. Further, in the current collecting member having such a configuration, since the coating layer suppresses the evaporation of Cr from the metal member, the generation of Cr poisoning of a single cell is suppressed, and as a result, the performance deterioration of the power generation unit is suppressed. be able to.

Japanese Unexamined Patent Publication No. 2011-99159

However, it is not possible to sufficiently suppress further growth of the oxide film layer only by forming a coating layer containing Co oxide on the surface of the metal member constituting the current collector member as in the above-mentioned conventional configuration. There is a problem that the increase in the electric resistance of the current collector member (that is, the decrease in the performance of the power generation unit) cannot be sufficiently suppressed.

It should be noted that such a problem is a collection of electrolytic cell units, which are constituent units of solid oxide-type electrolytic cells (hereinafter, also referred to as “SOEC”) that generate hydrogen by utilizing the electrolysis reaction of water. This is a common issue for electrical components. In this specification, the fuel cell power generation unit and the electrolytic cell unit are collectively referred to as an electrochemical reaction unit. Moreover, such a problem is common not only to SOFC and SOEC but also to other types of electrochemical reaction units. Further, such a problem is not limited to the current collecting member constituting the electrochemical reaction unit, but also a metal member containing Fe and Cr and an oxide film layer containing a Cr oxide arranged on the surface of the metal member. This is a common problem in general for conductive members including a coating layer containing Co oxide arranged on the surface of the oxide coating layer.

This specification discloses a technique capable of solving the above-mentioned problems.

The techniques disclosed herein can be realized, for example, in the following forms.

(1) The conductive member disclosed in the present specification is a conductive member, which contains a base containing Fe and Cr and Fe, Cr and Co, and has a Co concentration of 1.0 wt%. It is arranged on the surface composed of the metal member having the above and the alloy phase having a Co concentration higher than that of the base and the alloy phase in the metal member, and contains Cr oxide, and the Cr concentration is said. It includes an oxide film layer having a Cr concentration higher than that of the metal member, and a coating layer arranged on the surface of the oxide film layer opposite to the surface facing the metal member and containing Co oxide. According to the present conductive member, since the metal member has an alloy phase containing Co in a relatively high concentration, Cr from the metal member is compared with a configuration in which the metal member does not have such an alloy phase. Diffusion can be suppressed. Therefore, according to the present conductive member, further growth of the oxide film layer caused by Cr diffusion from the metal member can be effectively suppressed, and an increase in electrical resistance of the conductive member can be effectively suppressed. be able to.

(2) In the conductive member, when the strength of each element is specified by SEM-EDS in the alloy phase, the strength of Co may be lower than the strength of Cr. The higher the strength of Co in the alloy phase, the lower the Cr concentration tends to be. Further, when the Cr concentration is excessively low and the Co concentration is excessively high, the effect of suppressing Cr diffusion by Co becomes strong, the amount of Cr supplied relative to the amount of oxygen diffusion into the metal member becomes too small, and internal oxidation occurs in the metal member. There is a risk of According to this conductive member, since the strength of Co in the alloy phase is lower than the strength of Cr, it is possible to prevent the Cr concentration from being excessively low and the Co concentration from being excessively high in the alloy phase, and it is possible to prevent the metal member from becoming excessively high. The occurrence of internal oxidation can be suppressed.

(3) In the conductive member, the Co concentration of one portion in the alloy phase may be lower than the Co concentration of the portion away from the base portion than the one portion in the alloy phase. According to this conductive member, it is possible to prevent the Co concentration in the portion of the alloy phase close to the base from becoming excessive, and the difference in the coefficient of thermal expansion between the alloy phase and the base becomes excessive. As a result, it is possible to suppress the occurrence of defects (for example, peeling of the oxide film layer and the coating layer) caused by the distortion of the interface between the alloy phase and the base when the temperature changes.

(4) In the conductive member, the Co oxide contained in the coating layer may contain at least one element of Cr, Mn, Fe, Ni, Cu and Zn. According to the present conductive member, the coating layer can effectively suppress the growth of the oxide film layer and effectively suppress the evaporation of Cr from the metal member.

(5) In the conductive member, the conductive member may be a solid oxide type electrochemical reaction unit current collecting member. According to the present conductive member, an increase in the electric resistance of the conductive member can be effectively suppressed, and a decrease in the performance of the solid oxide-type electrochemical reaction unit can be suppressed.

The technique 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). It is realized in the form of an electrochemical reaction unit (fuel cell power generation unit or electrolytic cell unit) including, an electrochemical reaction cell stack (fuel cell stack or electrolytic cell stack) including a plurality of electrochemical reaction units, and a method for manufacturing them. It is possible.

It is a perspective view which shows the appearance structure of the fuel cell stack 100 in embodiment. It is explanatory drawing which shows the XZ cross-sectional structure of the fuel cell stack 100 at the position of II-II of FIG. It is explanatory drawing which shows the YZ cross-sectional structure of the fuel cell stack 100 at the position of III-III of FIG. It is explanatory drawing which shows the XZ cross section configuration of two power generation units 102 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 configuration of two power generation units 102 adjacent to each other at the same position as the cross section shown in FIG. It is explanatory drawing which shows the XY cross-sectional structure of the power generation unit 102 at the position of VI-VI of FIG. It is explanatory drawing which shows the XY cross-sectional structure of the power generation unit 102 at the position of VII-VII of FIG. It is explanatory drawing which shows the detailed structure of the current collector member 200 in this embodiment. It is explanatory drawing which shows an example of the specific result of the intensity of each element by SEM-EDS for the current collector member 200 in this embodiment. It is a flowchart which shows an example of the manufacturing method of the current collector member 200 in this embodiment. It is explanatory drawing which shows typically an example of the manufacturing method of the current collector member 200 in this embodiment. It is explanatory drawing which shows the performance evaluation result. It is explanatory drawing which shows the Co concentration in the metal member 190 of each sample. It is explanatory drawing which shows typically an example of the manufacturing method of the current collector member 200X of a comparative example.

A. Embodiment:
A-1. Constitution:
(Structure 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 the position II-II in FIG. 1 (and FIGS. 6 and 7 described later). It is explanatory drawing which shows the structure, and FIG. 3 is the explanatory view which shows the YZ cross section structure of the fuel cell stack 100 at the position of III-III of FIG. Each figure shows XYZ axes that are orthogonal to each other to identify the direction. In the present specification, for convenience, the Z-axis positive direction is referred to as an upward direction, and the Z-axis negative direction is referred to as a downward direction, but the fuel cell stack 100 is actually in a direction different from such an orientation. It may be installed. The same applies to FIGS. 4 and later.

The fuel cell stack 100 includes a plurality of (seven in this embodiment) 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 aggregate 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 holes (eight in this embodiment) penetrating in the vertical direction are formed on the peripheral edge of each layer (power generation unit 102, end plates 104, 106) constituting the fuel cell stack 100 in the Z direction. , 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 the communication holes 108.

A bolt 22 extending in the vertical direction is inserted into each communication hole 108, and the fuel cell stack 100 is fastened by the bolt 22 and the nuts 24 fitted on both sides of the bolt 22. As shown in FIGS. 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 forming 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 the 22 and the lower surface of the end plate 106 forming the lower end of the fuel cell stack 100. However, in the place where the gas passage member 27 described later is provided, the insulating sheets arranged on the upper side and the lower side of the gas passage member 27 and the gas passage member 27 between the nut 24 and the surface of the end plate 106, respectively. 26 is intervening. The insulating sheet 26 is made of, for example, a mica sheet, a ceramic fiber sheet, a ceramic dust 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 position is near the midpoint of one side (the side on the positive side of the X axis among the two sides parallel to the Y axis) on the outer circumference of the fuel cell stack 100 around the Z direction. In the space formed by the bolt 22 (bolt 22A) and the communication hole 108 through which the bolt 22A is inserted, the oxidant gas OG is introduced from the outside of the fuel cell stack 100, and the oxidant gas OG is generated for each power generation. It functions as an oxidizer gas introduction manifold 161 that is a gas flow path supplied to the unit 102, and is the midpoint of the side opposite to the side (the side on the negative side of the X axis among the two sides parallel to the Y axis). The space formed by the bolt 22 (bolt 22B) located in the vicinity and the communication hole 108 through which the bolt 22B is inserted provides the oxidant off-gas OOG, which is the gas discharged from the air chamber 166 of each power generation unit 102. It functions as an oxidizer gas discharge manifold 162 that discharges to the outside of the fuel cell stack 100. In this 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 positive side of the Y axis among the two sides parallel to the X axis) on the outer circumference of the fuel cell stack 100 around the Z direction. In the space formed by the bolt 22 (bolt 22D) located in the above and the communication hole 108 through which the bolt 22D is inserted, the fuel gas FG is introduced from the outside of the fuel cell stack 100, and the fuel gas FG is generated by each power generation. A bolt 22 that functions as a fuel gas introduction manifold 171 to be supplied to the unit 102 and is located near the midpoint of the opposite side (the side on the negative side of the Y axis of the two sides parallel to the X axis). The space formed by (bolt 22E) and the communication hole 108 through which the bolt 22E is inserted sends the fuel off-gas FOG, which is the gas discharged from the fuel chamber 176 of each power generation unit 102, to the outside of the fuel cell stack 100. It functions as a fuel gas discharge manifold 172 to be discharged. In the present embodiment, for example, a hydrogen-rich gas obtained by reforming city gas is used as the fuel gas FG.

The fuel cell stack 100 is provided with four gas passage members 27. Each gas passage member 27 has a hollow tubular main body 28 and a hollow tubular branch 29 branched from the side surface of the main body 28. The hole of the branch portion 29 communicates with the hole of the main body portion 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 28 of the gas passage member 27 arranged at the position of the bolt 22A forming the oxidant gas introduction manifold 161 communicates with the oxidant gas introduction manifold 161. The hole of the main body 28 of the gas passage member 27 arranged at the position of the bolt 22B forming 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 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 fuel gas. The hole of the main body 28 of the gas passage member 27 arranged at the position of the bolt 22E forming the discharge manifold 172 communicates with the fuel gas discharge manifold 172.

(Structure of end plates 104 and 106)
The pair of end plates 104 and 106 are substantially rectangular flat plate-shaped conductive members, and are made of, for example, stainless steel. One end plate 104 is arranged above the power generation unit 102 located at the top, and the other end plate 106 is arranged below the power generation unit 102 located at the bottom. A plurality of power generation units 102 are sandwiched by a pair of end plates 104 and 106 in a pressed state. 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.

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

As shown in FIGS. 4 and 5, the power generation unit 102 includes a single cell 110, a separator 120, an air pole side frame 130, an air pole side current collector 134, a fuel pole side frame 140, and a fuel pole side. It includes a current collector 144 and a pair of interconnectors 150 that form the uppermost layer and the lowermost layer of the power generation unit 102. Holes corresponding to the communication holes 108 through which the above-mentioned bolts 22 are inserted are formed in the peripheral portions of the separator 120, the air pole side frame 130, the fuel pole side frame 140, and the interconnector 150 in the Z direction.

The interconnector 150 is a substantially rectangular flat plate-shaped conductive member, and is made of, for example, ferritic stainless steel. The interconnector 150 ensures electrical continuity between the power generation units 102 and prevents mixing of reaction gases 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 certain 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 a pair of end plates 104 and 106, the power generation unit 102 located at the top of the fuel cell stack 100 does not have 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 has an electrolyte layer 112, a fuel electrode (anode) 116 arranged 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. It includes an air electrode (cathode) 114 arranged on the (upper side) and an intermediate layer 180 arranged between the electrolyte layer 112 and the air electrode 114. The single cell 110 of the present embodiment is a fuel pole support type single cell that supports other layers (electrolyte layer 112, air pole 114, intermediate layer 180) constituting the single cell 110 with the fuel pole 116.

The electrolyte layer 112 is a flat plate-shaped member that is substantially rectangular in the Z direction, and is a dense layer. The electrolyte layer 112 is formed of, for example, a solid oxide such as YSZ (yttria-stabilized zirconia), ScSZ (scandia-stabilized zirconia), SDC (samarium-doped ceria), GDC (gadrinium-doped ceria), and perovskite-type oxide. There is. 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 in the Z direction, and is a porous layer. The air electrode 114 is formed of, for example, a perovskite type oxide (for example, LSCF (lanternstrontium cobalt iron oxide), LSM (lanternstrontium manganese oxide), LNF (lantern nickel iron)).

The fuel electrode 116 is a substantially rectangular flat plate-shaped member having substantially the same size as the electrolyte layer 112 in the Z direction, and is a porous layer. The fuel electrode 116 is formed of, for example, a cermet composed 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). In the intermediate layer 180, 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 highly resistant substance (for example, SrZrO 3} ). Suppress.

The separator 120 is a frame-shaped member in which a substantially rectangular hole 121 penetrating in the vertical direction is formed near the center, and is formed of, for example, metal. The peripheral portion of the hole 121 in the separator 120 faces the peripheral edge of the surface of the electrolyte layer 112 on the side of the air electrode 114. 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 wax) arranged at the opposite portion thereof. The separator 120 partitions the air chamber 166 facing the air electrode 114 and the fuel chamber 176 facing the fuel electrode 116, and a gas leak from one electrode side to the other electrode side at the peripheral edge of the single cell 110. It is suppressed.

As shown in FIGS. 4 to 6, the air electrode side frame 130 is a frame-shaped member in which a substantially rectangular hole 131 penetrating in the vertical direction is formed near the center, and is formed of, for example, an insulator such as mica. ing. The hole 131 of the air electrode side frame 130 constitutes an air chamber 166 facing 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. .. Further, the air electrode side frame 130 electrically insulates between the pair of interconnectors 150 included in the power generation unit 102. Further, in the air electrode side frame 130, the oxidant gas supply communication hole 132 that communicates the oxidant gas introduction manifold 161 and the air chamber 166, and the oxidant gas that communicates 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 pole side frame 140 is a frame-shaped 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. .. Hole 141 of the fuel electrode side frame 140 constitutes a fuel chamber 176 facing the fuel electrode 116. The fuel electrode side frame 140 is in contact with the peripheral edge of the surface of the separator 120 facing the electrolyte layer 112 and the peripheral edge of the surface of the interconnector 150 facing the fuel electrode 116. Further, in the fuel electrode side frame 140, a fuel gas supply communication hole 142 that communicates the fuel gas introduction manifold 171 and the fuel chamber 176, and a fuel gas discharge communication hole 143 that communicates 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 arranged 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 connecting the electrode facing portion 145 and the interconnector facing portion 146. For example, nickel or nickel alloy. , Stainless steel, etc. The electrode facing portion 145 is in contact with the surface of the fuel pole 116 opposite to the side facing the electrolyte layer 112, and the interconnector facing portion 146 is on the surface of the interconnector 150 facing the fuel pole 116. Are in contact. However, as described above, since the power generation unit 102 located at the bottom of the fuel cell stack 100 does not have the lower interconnector 150, the interconnector facing portion 146 in the power generation unit 102 is the lower end plate. It is in contact with 106. Since the fuel pole side current collector 144 has such a configuration, the fuel pole 116 and the interconnector 150 (or the end plate 106) are electrically connected to each other. A spacer 149 formed of, for example, mica is arranged 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 follow. Good electrical connection with is maintained.

As shown in FIGS. 4 to 6, the air electrode side current collector 134 is arranged 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, for example, ferritic stainless steel. The air pole side current collector 134 is in contact with the surface of the air pole 114 on the side opposite to the side facing the electrolyte layer 112 and the surface of the interconnector 150 on the side facing the air pole 114. However, as described above, since the power generation unit 102 located at the top of the fuel cell stack 100 does not have the upper interconnector 150, the air electrode side current collector 134 in the power generation unit 102 has an upper end plate. It is in contact with 104. 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, in the integrated member (hereinafter referred to as "metal member 190"), the flat plate-shaped portion orthogonal to the vertical direction (Z-axis direction) functions as the interconnector 150, and the air electrode is formed from the flat plate-shaped portion. A plurality of current collector elements 135 formed so as to project toward 114 function as an air electrode side current collector 134.

As shown in FIG. 5, an _{oxide film layer 194 containing a Cr oxide (for example, Cr 2} O ₃ (chromia)) is formed on the surface of the metal member 190. Further, as shown in FIGS. 4 and 5, the surface of the metal member 190 (more specifically, the surface of the oxide film layer 194 formed on the surface of the metal member 190) is covered with the conductive coating layer 196. It has been passed. In the following description, unless otherwise specified, the metal member 190 (an integral member of the air electrode side current collector 134 and the interconnector 150) means "a metal member 190 covered with a coating layer 196".

As shown in FIGS. 4 and 5, the air electrode 114 and the air electrode side current collector 134 (current collector element 135) are bonded by a conductive bonding layer 138. The bonding layer 138 is, for example, an oxide having a spinel-type crystal structure (for example, Mn _1.5 Co _1.5 O ₄ or _{Mn Co 2} O ₄ , ZnCo ₂ O ₄ , ZnMn ₂ O ₄ , ZnMn CoO ₄ , CuMn ₂ O). It is formed by _4). The bonding layer 138 electrically connects the air electrode 114 and the air electrode side current collector 134. Earlier, it was explained that the air electrode side current collector 134 is in contact with the surface of the air electrode 114, but to be precise, a bonding layer 138 is formed between the air electrode side current collector 134 and the air electrode 114. It is intervening.

In the following description, the metal member 190 (an integral member of the interconnector 150 and the current collector 134 on the air electrode side), the oxide film layer 194 formed on the surface of the metal member 190, and the metal member in the oxide film layer 194. The coating layer 196 formed on the surface opposite to the surface facing 190 is collectively referred to as a current collector member 200. The current collector member 200 is electrically connected to the air electrode 114 via the junction layer 138, and is electrically connected to the fuel electrode 116 via the fuel electrode side current collector 144. The configuration of the current collector member 200 will be described in detail later. The current collecting member 200 corresponds to a conductive member within the scope of claims.

A-2. Operation of fuel cell stack 100:
As shown in FIGS. 2 and 4, the oxidant gas OG is supplied via 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 holes of the branch portion 29 and the main body portion 28 of the gas passage member 27, 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 via 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 holes of the branch portion 29 and the main body portion 28 of the gas passage member 27, and the fuel gas supply communication of each power generation unit 102 is performed from the fuel gas introduction manifold 171. It is supplied to the fuel chamber 176 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 the electrochemical reaction of the oxidant gas OG and the fuel gas FG in the single cell 110. Will be. 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 current collecting member 200 (aggregate of the metal member 190, the oxide film layer 194, and the coating layer 196) via the bonding layer 138, and is a fuel electrode. The 116 is electrically connected to the current collector 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, the electric energy generated in each power generation unit 102 is taken out from the end plates 104 and 106 that function as the output terminals of the fuel cell stack 100. Since the SOFC generates electricity at a relatively high temperature (for example, 700 ° C. to 1000 ° C.), the fuel cell stack 100 is a heater (for example, after the start-up, until the high temperature can be maintained by the heat generated by the power generation. It may be heated by (not shown).

As shown in FIGS. 2 and 4, 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 through the oxidant gas discharge communication hole 133, and further oxidized. The fuel cell stack 100 is passed through the holes of the main body 28 and the branch 29 of the gas passage member 27 provided at the position of the agent gas discharge manifold 162, and the gas pipe (not shown) connected to the branch 29. It is discharged to the outside of. 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 through the fuel gas discharge communication hole 143, and further, the fuel gas. To the outside of the fuel cell stack 100 via the holes of the main body 28 and the branch 29 of the gas passage member 27 provided at the position of the discharge manifold 172, and via a gas pipe (not shown) connected to the branch 29. It is discharged.

A-3. Detailed configuration of the current collector member 200:
FIG. 8 is an explanatory diagram showing a detailed configuration of the current collector member 200 according to the present embodiment. FIG. 8 shows an enlarged cross-sectional structure of the X1 portion of FIG. As described above, the current collector 200 includes a metal member 190 (an integral member of the air electrode side current collector 134 and the interconnector 150), an oxide film layer 194 arranged on the surface of the metal member 190, and oxidation. The coating layer 194 includes a coating layer 196 arranged on a surface opposite to the surface facing the metal member 190.

As shown in FIG. 8, the metal member 190 includes a base portion 191 and an alloy phase 192 forming a surface of the metal member 190 facing the oxide film layer 194. In the present embodiment, the base 191 of the metal member 190 contains Fe as a main component and Cr at a concentration of 16 wt% or more. In the present specification, the main component means the component having the highest concentration. Further, the base portion 191 may contain Co, but even in that case, the Co concentration in the base portion 191 is less than 1 wt%.

Further, the alloy phase 192 of the metal member 190 contains Fe as a main component, Cr at a concentration of 16 wt% or more, and Co at a concentration of 1 wt% or more. In the present embodiment, the Co concentration of the alloy phase 192 of the metal member 190 has a continuous or stepwise gradient so as to be lower as it is closer to the base 191 and higher as it is farther from the base 191. That is, the Co concentration of one portion of the alloy phase 192 is lower than the Co concentration of the portion of the alloy phase 192 that is farther from the base 191 than the above-mentioned one portion. Further, as described above, the base portion 191 may contain Co, but even in that case, the Co concentration of the alloy phase 192 is higher than the Co concentration of the base portion 191.

The oxide film layer 194 contains Cr oxide (for example, Cr ₂ O ₃ (chromia)). The Cr concentration of the oxide film layer 194 is higher than the Cr concentration of the metal member 190. The thickness of the oxide film layer 194 is preferably 0.5 μm or more, for example. Since the oxide film layer 194 has low oxygen permeability, it suppresses the oxidation of Fe, which is more unfavorable for the metal member 190. That is, the oxide film layer 194 functions as an oxidation resistant film. On the other hand, since the oxide film layer 194 has a relatively high electric resistance, it is not preferable that the oxide film layer 194 further grows with the use of, for example, the fuel cell stack 100.

The coating layer 196 is a conductive layer containing a Co oxide. In the present embodiment, the coating layer 196 has a spinel-type crystal structure and contains Co oxides containing at least one element of Cr, Mn, Fe, Ni, Cu, and Zn (for example, CrCo ₂ O ₄ , MnCo). ₂ O _4, is formed by _{FeCo 2 O 4, NiCo 2 O} 4, CuCo 2 O 4, ZnCo 2 O 4, ZnMnCoO 4 , etc.). The thickness of the coating layer 196 is preferably 5 μm or more, for example. Since the coating layer 196 suppresses the permeation of oxygen, the growth of the oxide film layer 194 having a high electric resistance can be suppressed, and as a result, the electric resistance of the current collecting member 200 increases (that is, the performance of the power generation unit 102). (Decrease) can be suppressed. Further, since the coating layer 196 suppresses the evaporation of Cr from the metal member 190, it is possible to suppress the generation of Cr poisoning of the electrode (for example, the air electrode 114) of the single cell 110, and as a result, the power generation unit 102. Performance degradation can be suppressed.

FIG. 9 is an explanatory diagram showing an example of a specific result of the intensity of each element by SEM-EDS for the current collector 200 in the present embodiment. FIG. 9 shows the relative intensities of each element (Fe, Cr, Co, Mn) on a line parallel to the Z axis of the cross section of the current collector member 200. As shown in FIG. 9, in the current collector 200 of the present embodiment, the strength of Co is lower than the strength of Cr at the base 191 of the metal member 190.

A-4. Manufacturing method of current collector member 200:
Next, a method of manufacturing the current collector member 200 will be described. FIG. 10 is a flowchart showing an example of a method of manufacturing the current collector 200 according to the present embodiment. Further, FIG. 11 is an explanatory diagram schematically showing an example of a method of manufacturing the current collector member 200 according to the present embodiment.

First, the metal base material 210 is prepared (S110, A in FIG. 11). The metal base material 210 is, for example, ferritic stainless steel, which contains Fe as a main component and Cr at a concentration of 16 wt% or more.

Next, a dense Co-containing layer 220 is formed on the surface of the metal base material 210 (S120, B in FIG. 11). The Co-containing layer 220 contains various elements depending on the composition of the coating layer 196 formed later. In the present embodiment, the Co-containing layer 220 contains Mn so that the coating layer 196 formed later contains Mn. Further, in the present embodiment, Co is mainly contained in the Co-containing layer 220 in the form of a metal or an alloy, and the Co-containing layer 220 is densely formed. Such formation of the Co-containing layer 220 can be realized by, for example, plating (electroplating or the like) or sputtering.

Next, the laminate of the metal base material 210 and the Co-containing layer 220 is heat-treated at a predetermined temperature for a predetermined time (S130, C in FIG. 11). By performing the heat treatment, Co contained in the Co-containing layer 220 diffuses into the metal base material 210. As a result, the portion of the metal base material 210 close to the Co-containing layer 220 becomes an alloy phase 192 containing Co in addition to Fe and Cr at a concentration of a certain level or higher (specifically, a concentration of 1 wt% or higher) (FIG. 11 D). The other portion of the metal base material 210 is the base portion 191 containing Fe and Cr but having a Co concentration of less than 1 wt%.

Further, by performing the heat treatment of S130, Cr contained in the metal base material 210 diffuses and reacts with oxygen in the atmosphere. As a result, an oxide film layer 194 containing a Cr oxide (for example, Cr ₂ O ₃ (chromia)) is formed on the surface of the metal member 190 (D in FIG. 11).

Further, by performing the heat treatment of S130, Co and other elements (Mn) contained in the Co-containing layer 220 diffuse and react with oxygen in the atmosphere. _{As a result, a coating layer 196 containing a Co oxide (for example, MnCo 2} O ₄ ) is formed on the surface of the oxide coating layer 194 (D in FIG. 11). The current collector 200 having the above-described configuration is manufactured by the manufacturing method described above.

A-5. Effect of this embodiment:
As described above, the current collecting member 200 in the present embodiment has an oxide film layer arranged on a surface composed of a metal member 190 having a base portion 191 and an alloy phase 192 and an alloy phase 192 in the metal member 190. 194 and a coating layer 196 arranged on a surface of the oxide film layer 194 opposite to the surface facing the metal member 190 are provided. The base 191 of the metal member 190 contains Fe and Cr. Further, the alloy phase 192 of the metal member 190 contains Fe, Cr, and Co. The Co concentration of the alloy phase 192 is 1.0 wt% or more and higher than the Co concentration of the base 191. The oxide film layer 194 contains Cr oxide, and the Cr concentration is higher than the Cr concentration of the metal member 190. The coating layer 196 contains a Co oxide. As described above, in the current collector 200 of the present embodiment, the coating layer 196 suppresses oxygen permeation, thereby suppressing the growth of the oxide film layer 194 having high electrical resistance. Therefore, the electrical resistance of the current collector 200 is reduced. The increase (that is, the decrease in the performance of the power generation unit 102) can be suppressed. Further, in the current collector 200 of the present embodiment, the coating layer 196 suppresses the evaporation of Cr from the metal member 190, thereby suppressing the generation of Cr poisoning of the electrode (for example, the air electrode 114) of the single cell 110. As a result, the performance deterioration of the power generation unit 102 can be suppressed. Further, in the current collecting member 200 of the present embodiment, since the metal member 190 has an alloy phase 192 containing Co in a relatively high concentration, the metal member 190 is compared with a configuration in which the metal member 190 does not have such an alloy phase 192. Therefore, Cr diffusion from the metal member 190 can be suppressed. Therefore, according to the current collector 200 of the present embodiment, further growth of the oxide film layer 194 caused by Cr diffusion from the metal member 190 can be effectively suppressed, and the electric resistance of the current collector 200 can be reduced. The increase can be effectively suppressed, and as a result, the performance deterioration of the power generation unit 102 can be effectively suppressed.

As the metal member 190 constituting the current collecting member 200, a metal material (for example, austenitic stainless steel) containing Co at a relatively high concentration (specifically, at a concentration of 1 wt% or more) is used. Similarly, it is considered that further growth of the oxide film layer 194 caused by Cr diffusion from the metal member 190 can be suppressed. However, a metal material containing Co in a relatively high concentration as a whole is often relatively expensive, and its coefficient of thermal expansion is large with the coefficient of thermal expansion of other members constituting the power generation unit 102. The use of such metallic materials is often undesirable because they may differ. According to the current collector 200 of the present embodiment, the oxide film layer 194 due to Cr diffusion from the metal member 190 can be further grown without using a metal material containing Co in a relatively high concentration as a whole. It can be said that it is very useful because it can be effectively suppressed.

Further, in the current collector 200 of the present embodiment, when the strength of each element is specified by SEM-EDS in the alloy phase 192 of the metal member 190, the strength of Co is lower than the strength of Cr. That is, the ratio of the strength of Co to the sum of the strength of Co and the strength of Cr in the alloy phase 192 is 50% or less. The higher the strength of Co in the alloy phase 192, the lower the Cr concentration tends to be. In a configuration in which the strength of Co is substantially the same as the strength of Cr, the Cr concentration is about 18 wt% and the Co concentration is about 20 wt%. In such a configuration, the effect of suppressing Cr diffusion by Co becomes stronger, the amount of Cr supplied relative to the amount of oxygen diffusion into the metal member 190 becomes excessive, and internal oxidation may occur in the metal member 190. In the current collecting member 200 of the present embodiment, since the strength of Co in the alloy phase 192 is lower than the strength of Cr, it is possible to prevent the Cr concentration from being excessively low and the Co concentration from being excessively high in the alloy phase 192. , Occurrence of internal oxidation in the metal member 190 can be suppressed. From the viewpoint of suppressing the occurrence of internal oxidation in the metal member 190, the ratio of the strength of Co to the total of the strength of Co and the strength of Cr in the alloy phase 192 is more preferably 40% or less, further preferably 30% or less. preferable.

Further, in the current collector 200 of the present embodiment, the Co concentration of one portion of the alloy phase 192 is lower than the Co concentration of the portion of the alloy phase 192 that is farther from the base portion 191 than the above-mentioned one portion. Therefore, according to the current collecting member 200 of the present embodiment, it is possible to prevent the Co concentration of the portion of the alloy phase 192 close to the base 191 from becoming excessive, and the heat between the alloy phase 192 and the base 191 can be suppressed. It is possible to prevent the difference in expansion coefficient from becoming excessive, and as a result, defects caused by distortion of the interface between the alloy phase 192 and the base 191 when the temperature changes (for example, the oxide film layer 194 and the coating layer 196). The occurrence of peeling) can be suppressed.

A-6. Performance evaluation:
A sample of the current collector member 200 was prepared, and the performance was evaluated using the sample. FIG. 12 is an explanatory diagram showing the performance evaluation result.

A-6-1. For each sample:
As shown in FIG. 12, two samples (samples S1 and S2) were used for this performance evaluation. Sample S1 is a sample of the current collector member 200 of the present embodiment described above. When preparing the sample S1 (see FIGS. 10 and 11), a ferrite stainless steel containing Fe as a main component and Cr at a concentration of 20 wt was used as the metal base material 210. Further, the Co-containing layer 220 containing Co and Mn was formed by electrolytic plating. The heat treatment conditions were 950 ° C. for 2 hours. When the surface (that is, the coating layer 196) of the current collector 200 of the sample S1 produced by such a production method was analyzed by XRD, it was confirmed that _{the crystal structure was MnCo 2} O _4. Further, when the cross section of the current collector member 200 of the sample S1 was observed by SEM-EDS, the thickness of the alloy phase 192 (that is, the portion where the Co concentration was 1 wt% or more) in the metal member 190 was 40 μm, and the oxide film layer. The thickness of 194 was 1.0 μm. Although not shown in FIG. 12, the thickness of the coating layer 196 was 10 μm. Further, as shown in FIG. 13, the Co concentration in the alloy phase 192 (the portion from the surface of the metal member 190 to 40 μm) constituting the current collecting member 200 of the sample S1 is closer to the surface of the metal member 190 (that is, that is). It was confirmed that there is a concentration gradient that is higher as the distance from the base 191 is higher and lower as the distance from the surface of the metal member 190 (that is, closer to the base 191).

On the other hand, sample S2 is a sample of the current collector member 200X of the comparative example. The current collecting member 200X of the comparative example is different from the current collecting member 200 of the present embodiment in its manufacturing method. FIG. 14 is an explanatory diagram schematically showing an example of a method of manufacturing the current collector member 200X of the comparative example. In the method for manufacturing the current collector member 200X of the comparative example, first, as in the present embodiment, the metal base material 210 (specifically, a ferrite stainless steel containing Fe as a main component and Cr at a concentration of 20 wt). ) Is prepared (A in FIG. 14). Next, a Co-containing layer 220 is formed on the surface of the metal base material 210 (B in FIG. 14). At this time, the Co-containing layer 220 is formed by a method other than plating or sputtering (for example, thermal spraying). As a result, the formed Co-containing layer 220 is in a state in which Co and Mn are mainly contained in the form of oxides.

Next, the laminate of the metal base material 210 and the Co-containing layer 220 is heat-treated under the same conditions as in the present embodiment (C in FIG. 14). By this heat treatment, Cr contained in the metal base material 210 reacts with oxygen in the atmosphere and Cr oxide (for example, Cr ₂ O ₃ (chromia)) is formed on the surface of the metal member 190 as in the present embodiment. The oxide film layer 194 containing the oxide film layer 194 is formed, and Co and other elements (Mn) contained in the Co-containing layer 220 react with oxygen in the atmosphere to form a Co oxide (for example, Co. , MnCo ₂ O ₄ ) is formed (D in FIG. 14). On the other hand, since Co is mainly contained in the Co-containing layer 220 in the form of an oxide, the amount of Co diffused from the Co-containing layer 220 into the metal substrate 210 during the heat treatment is higher than that in the present embodiment. Very few. Therefore, in the metal member 190, a portion (specifically, an alloy phase 192 in the present embodiment) containing Co at a concentration equal to or higher than a certain level (specifically, a concentration of 1 wt% or higher) is not formed, and the entire metal member 190 is formed with the base portion 191. Become.

When the surface (that is, the coating layer 196) of the current collector member 200X of the sample S2 produced by such a production method was analyzed by XRD, it was confirmed that _{the crystal structure was MnCo 2} O _4. Further, when the cross section of the current collector member 200X of the sample S2 was observed by SEM-EDS, the metal member 190 did not have a portion having a Co concentration of 1 wt% or more. The thickness of the oxide film layer 194 was 1.0 μm, and the thickness of the coating layer 196 was 10 μm.

A-6-2. Evaluation method and evaluation result:
In this performance evaluation, the current collector 200 (200X) of the sample S1 and the sample S2 is oxidized in an atmospheric atmosphere at 900 ° C. for 1000 hours, and then the cross section of each sample is subjected to SEM-EDS. The thickness of the oxide film layer 194 was measured by observing.

As shown in FIG. 12, in the current collector 200 of sample S1, the thickness of the oxide film layer 194 after the oxidation treatment is 3.8 μm, and the amount of increase in the thickness of the oxide film layer 194 from the initial state is 2. It was 0.8 μm. In the current collecting member 200 of the sample S1, since the metal member 190 has an alloy phase 192 containing Co at a certain concentration or more (specifically, a concentration of 1 wt% or more), the diffusion of Cr from the metal member 190 is prevented. It is considered that the suppression was achieved and the further growth of the oxide film layer 194 could be effectively suppressed.

On the other hand, in the current collector member 200X of sample S2, the thickness of the oxide film layer 194 after the oxidation treatment was 4.2 μm, and the amount of increase in heat of the oxide film layer 194 from the initial state was 3.2 μm. In the current collecting member 200X of the sample S2, since the metal member 190 does not have a portion (alloy phase 192) containing Co at a certain concentration or more (specifically, a concentration of 1 wt% or more), the metal member 190 starts from the metal member 190. It is probable that the diffusion of Cr was not suppressed and the further growth of the oxide film layer 194 could not be effectively suppressed.

According to the performance evaluation described above, when the metal member 190 has the alloy phase 192 containing Co at a relatively high concentration, Cr diffusion from the metal member 190 can be suppressed by the presence of the alloy phase 192, and the oxide film It was confirmed that further growth of layer 194 can be effectively suppressed.

B. Modification example:
The technique disclosed in the present specification is not limited to the above-described embodiment, and can be transformed into various forms without departing from the gist thereof, and for example, the following modifications are also 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 can be variously modified. For example, in the above embodiment, the alloy phase 192 of the metal member 190 constituting the current collecting member 200 has a Co concentration of 1.0 wt% or more, but the alloy phase 192 has a Co concentration of 1.5 wt%. It may be a portion of% or more, a portion having a Co concentration of 2.0 wt% or more, a portion having a Co concentration of 2.5 wt% or more, and a Co concentration of 3. It may be a portion of 0 wt% or more.

Further, in the above embodiment, when the strength of each element is specified by SEM-EDS in the alloy phase 192 of the metal member 190 constituting the current collector member 200, the strength of Co is lower than the strength of Cr, but that is not always the case. It does not have to be such a configuration. Further, in the above embodiment, the Co concentration of one portion of the metal member 190 constituting the current collecting member 200 in the alloy phase 192 is lower than the Co concentration of the portion of the alloy phase 192 that is farther from the base portion 191 than the above one portion. However, it does not necessarily have to be such a configuration.

Further, in the above embodiment, the interconnector 150 and the air electrode side current collector 134 (current collector element 135) are integrated members (metal member 190), but the interconnector 150 and the air electrode side current collector 134 may be a separate member. In that case, the present invention can also be applied to a current collector member composed of an interconnector 150 or an air electrode side current collector 134, an oxide coating layer 194, and a coating layer 196.

Further, in the above embodiment, the air electrode side current collector 134 (current collector element 135) is in contact with the air electrode 114 via the junction layer 138, but the air electrode side current collector 134 is interposed via the junction layer 138. It may be in contact with the air electrode 114 without being in contact with the air electrode 114.

Further, in the above embodiment, the SOFC that generates power by utilizing the electrochemical reaction between hydrogen contained in the fuel gas and oxygen contained in the oxidizing agent gas is targeted, but the present invention comprises an electrolysis reaction of water. It is also applicable to an electrolytic cell unit, which is a constituent unit of a solid oxide fuel cell (SOEC) that uses it to generate hydrogen, and an electrolytic cell stack having a plurality of electrolytic cell units. The configuration of the electrolytic cell stack is not described in detail here because it is known as described in, for example, Japanese Patent Application Laid-Open No. 2016-81813, but is generally the same as the fuel cell stack 100 in the above-described embodiment. It is the composition of. 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 cell. However, during the operation of the electrolytic cell stack, a voltage is applied between both electrodes so that the air electrode 114 is positive (anode) and the fuel electrode 116 is negative (cathode), and the voltage is applied through the communication hole 108. Water vapor as a raw material gas is supplied. As a result, an electrolysis reaction of water occurs in each electrolytic cell unit, hydrogen gas is generated in the fuel chamber 176, and hydrogen is taken out to the outside of the electrolytic cell stack through the communication hole 108. Even in the electrolytic cell unit and the electrolytic cell stack having such a configuration, by adopting the current collecting member 200 having the above-described configuration, further growth of the oxide film layer 194 caused by Cr diffusion from the metal member 190 is effective. It is possible to effectively suppress an increase in the electric resistance of the current collecting member 200, and as a result, it is possible to effectively suppress a decrease in the performance of each electrolytic cell.

Further, in the above embodiment, the solid oxide fuel cell (SOFC) has been described as an example, but the present invention also applies to other types of fuel cells (or electrolytic cells) such as a molten carbonate fuel cell (MCFC). Applicable. Further, the present invention is not limited to the current collecting member constituting the electrochemical reaction unit, but also includes a metal member containing Fe and Cr, an oxide film layer containing a Cr oxide arranged on the surface of the metal member, and the like. It is generally applicable to conductive members including a coating layer containing Co oxide arranged on the surface of the oxide film layer.

22: Bolt 24: Nut 26: Insulation sheet 27: Gas passage member 28: Main body 29: Branch 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 pole 116: Fuel pole 120: Separator 121: Hole 124: Joint 130: Air pole side frame 131: Hole 132: Oxidizing gas supply communication hole 133: Oxidizing gas discharge communication hole 134: Air Polar side current collector 135: Current collector element 138: Junction layer 140: Fuel pole side frame 141: Hole 142: Fuel gas supply communication hole 143: Fuel gas discharge communication hole 144: Fuel pole side current collector 145: Opposite electrode Part 146: Interconnector facing part 147: Connecting part 149: Spacer 150: Interconnector 161: Oxidizing gas introduction manifold 162: Oxidizing 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 191: Base 192: Alloy phase 194: Oxide film layer 196: Coating layer 200: Current collector 210: Metal substrate 220: Co-containing layer

Claims (7)

A conductive member used as a current collector for an electrochemical reaction unit.
Fe is contained as a main component which is the highest concentration component, and a base containing Cr at a concentration of 16 wt% or more and a base.
Fe is contained as a main component which is the highest concentration component, Cr is contained at a concentration of 16 wt% or more, Co is contained at a concentration of 1.0 wt% or more, and the Co concentration is that of the base. An alloy phase higher than the Co concentration and
With metal members
Oxidation that is arranged on the surface of the metal member composed of the alloy phase, formed of Cr oxide, has a Cr concentration higher than the Cr concentration of the metal member, and has a thickness of 0.5 μm or more and 3.8 μm or less. With the coating layer,
Co which is arranged on the surface of the oxide film layer opposite to the surface facing the metal member and has a spinel-type crystal structure containing at least one element of Cr, Mn, Fe, Ni, Cu and Zn. A coating layer formed of oxide and having a thickness of 5 μm or more and 10 μm or less,
A conductive member comprising. In the conductive member according to claim 1,
A conductive member, characterized in that the strength of Co is lower than the strength of Cr when the strength of each element is specified by SEM-EDS in the alloy phase. In the conductive member according to claim 1 or 2.
A conductive member, characterized in that the Co concentration in the alloy phase increases as the distance from the base portion increases. The conductive member according to any one of claims 1 to 3.
The conductive member is a solid oxide type electrochemical reaction unit current collecting member. It is an electrochemical reaction unit
An electrochemical reaction single cell containing an electrolyte layer containing a solid oxide and an air electrode and a fuel electrode facing each other in the first direction across the electrolyte layer.
The first to the third aspects of the electrochemical reaction single cell, which are arranged on one side in the first direction and function as a current collecting member electrically connected to the air electrode or the fuel electrode. The conductive member according to any one of the above,
An electrochemical reaction unit characterized by comprising. In the electrochemical reaction unit according to claim 5,
The electrochemical reaction unit is an electrochemical reaction unit, which is a fuel cell power generation unit. In an electrochemical reaction cell stack having a plurality of electrochemical reaction units arranged side by side in the first direction.
An electrochemical reaction cell stack, wherein at least one of the plurality of electrochemical reaction units is the electrochemical reaction unit according to claim 5 or 6.

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