JP2017154968A - Joint material precursor, electrochemical reaction cell stack, and their production methods - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the conductivity of a joint material obtainable by the firing of a joint material precursor.SOLUTION: A conductive joint material joining the first conductive member and the second conductive member being a fired compact containing spinel type transition metal composite oxide including the first metallic element and the second metallic element. The joint material precursor in a state before the firing of the joint material includes: organic matter; and a plurality of the respective first particles having a metallic oxide part composed of the oxide of the first metallic element and a metallic part composed of the second metallic element.SELECTED DRAWING: Figure 7

Description

  The technology disclosed by the present specification relates to a bonding material precursor.

  A solid oxide fuel cell (hereinafter also 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 also simply referred to as “power generation unit”), which is the minimum unit of SOFC power generation, is a fuel including an electrolyte layer containing a solid oxide and an air electrode and a fuel electrode facing each other across the electrolyte layer. A single battery cell (hereinafter, also simply referred to as “single cell”) and a conductive current collecting member disposed on the air electrode side of the single cell in order to collect electric power generated in the single cell. The air electrode and the current collecting member are joined together by a conductive joining material, whereby the air electrode and the current collecting member are electrically connected.

As a bonding material for bonding the air electrode and the current collecting member, for example, a spinel-type transition metal composite oxide (for example, MnCo) having a first metal element (for example, Mn) and a second metal element (for example, Co) is used. A fired body containing ₂ O ₄ ) is used (see, for example, Patent Document 1). The bonding material is formed by firing the bonding material precursor in a state before firing of the bonding material in a state of being disposed between the air electrode and the current collecting member. Since the spinel-type transition metal composite oxide has high conductivity, the formed bonding material also has high conductivity.

  Conventionally, as a raw material for a bonding material precursor, in addition to an organic substance as a binder, for example, a metal oxide particle (for example, MnO particle) composed of an oxide of a first metal element and a second metal element are used. A mixed powder with metal particles (for example, Co particles) or a powder of a spinel type transition metal composite oxide itself is used.

JP 2007-141842 A

A spinel-type transition metal composite oxide having a first metal element and a second metal element is formed by mutual diffusion of the first metal element and the second metal element contained in the raw material. When a mixed powder of metal oxide particles composed of an oxide of a first metal element and metal particles composed of a second metal element is used as a raw material for a bonding material precursor as in the above-described conventional technology In the bonding material precursor, there are places where the first metal elements are arranged unevenly and places where the second metal elements are arranged unevenly. For this reason, during firing, mutual diffusion between the first metal element and the second metal element is less likely to occur at locations where such a disposition in the bonding material precursor is large, and the single conductivity is relatively low. An oxide of one metal element (for example, Mn ₃ O ₄ or Co ₃ O ₄ ) is easily generated. Therefore, the conductivity of the bonding material obtained by firing is lowered.

  In addition, when the powder of the spinel-type transition metal composite oxide itself is used as a raw material for the bonding material precursor as in the above-described prior art, the spinel-type transition metal composite oxide exists stably even at high temperatures. Since it is an oxide, interdiffusion between the first metal element and the second metal element hardly occurs during firing. As a result, the area of the contact portion between the particles that become a conductive path in the bonding material is reduced, and the conductivity of the bonding material obtained by firing is also lowered.

  Note that such a problem is that air contained in an electrolytic cell unit, which is the minimum unit of a solid oxide electrolytic cell (hereinafter also referred to as “SOEC”) that generates hydrogen using an electrolysis reaction of water. This is also a common problem for the bonding material precursor that is in a state before firing of the bonding material for bonding the electrode and the current collecting member. In this specification, the power generation unit and the electrolysis cell unit are collectively referred to as an electrochemical reaction unit. Furthermore, such a problem is not limited to the two members constituting the electrochemical reaction unit, but is a bonding material in a state before firing of the bonding material for bonding the first conductive member and the second conductive member. This is a problem common to precursors.

  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 bonding material precursor disclosed in this specification is a fired body including a spinel-type transition metal composite oxide having a first metal element and a second metal element, and has a first conductivity. A metal precursor composed of an organic substance and an oxide of the first metal element, which is a pre-baking state of a conductive bonding material for bonding a member and a second conductive member A plurality of first particles each having a physical part and a metal part composed of the second metal element. According to the present bonding material precursor, the deviation of the arrangement of the metal oxide portion and the metal portion in the bonding material precursor is reduced, and the number of places where the metal oxide portion and the metal portion are in contact increases, In addition, the first metal element contained in the metal oxide portion and the second metal element contained in the metal portion are likely to be interdiffused, and the interdiffusion is completed in a short time. A bonding material containing a large number of oxides is formed, and the conductivity of the bonding material can be increased.

(2) In the bonding material precursor, each of the first particles may include a plurality of the metal oxide portions and a plurality of the metal portions. According to the present bonding material precursor, there are more portions where the metal oxide portion and the metal portion are in contact with each other in the bonding material precursor, and the first metal element and the metal contained in the metal oxide portion during firing. Interdiffusion with the second metal element contained in the portion is more likely to occur, and a bonding material containing more uniform spinel-type transition metal composite oxide is formed, so that the conductivity of the bonding material is made higher. Can do.

(3) In the bonding material precursor, the number of the first particles is at least one of metal oxide particles composed only of the metal oxide portion and metal particles composed only of the metal portion. It is good also as a structure larger than the number of other particle | grains. According to the present bonding material precursor, since the number of the first particles in the bonding material precursor is larger than the number of the other particles, the number of the first particles in the bonding material precursor is larger than the number of the other particles. Compared to a small configuration, there are more portions where the metal oxide portion and the metal portion are in contact with each other, and during the firing, mutual diffusion between the first metal element and the second metal element is more likely to occur, and uniform. Since a bonding material containing more spinel-type transition metal composite oxide is formed, the conductivity of the bonding material can be further increased.

(4) In the bonding material precursor, the first metal element may be Mn, and the second metal element may be any one of Co, Cu, and Zn. Since such a spinel type transition metal composite oxide having the first metal element and the second metal element has a relatively high conductivity, the bonding material precursor is fired according to this bonding material precursor. Thus, the conductivity of the bonding material obtained can be made extremely high.

(5) In the bonding material precursor, the first conductive member includes an electrolyte layer including a solid oxide, and an air electrode and a fuel electrode facing each other with the electrolyte layer interposed therebetween. It is good also as a structure which is the said air electrode in a cell. According to the present bonding material precursor, the conductivity between the air electrode and the second conductive member in the electrochemical reaction unit cell can be improved by increasing the conductivity of the bonding material.

(6) In the bonding material precursor, the second conductive member includes the electrochemical reaction single cell and a current collecting member disposed on the air electrode side of the electrochemical reaction single cell. It is good also as a structure which is the said current collection member in an electrochemical reaction unit. According to the present bonding material precursor, the conductivity between the air electrode and the current collecting member in the electrochemical reaction unit can be improved by increasing the conductivity of the bonding material.

(7) The method for manufacturing a bonding material precursor disclosed in the present specification is a fired body including a spinel-type transition metal composite oxide having a first metal element and a second metal element. A method for producing a bonding material precursor in a state before firing of a conductive bonding material for bonding the conductive member and the second conductive member, wherein the first metal element and the second metal A step of producing a raw material powder by reducing a spinel-type transition metal composite oxide containing an element, and a step of producing the bonding material precursor by mixing the raw material powder and an organic substance. According to the manufacturing method of the present bonding material precursor, most of the plurality of particles contained in the raw material powder are composed of the metal oxide portion composed of the oxide of the first metal element and the second metal element. Since it can be set as the 1st particle | grains which have a metal part, the electroconductivity of the joining material obtained by baking of the manufactured joining material precursor can be made high.

(8) In the manufacturing method of the bonding material precursor, the first metal element may be Mn, and the second metal element may be any one of Co, Cu, and Zn. Since such a spinel type transition metal composite oxide having the first metal element and the second metal element has a relatively high conductivity, it is manufactured according to the method for manufacturing the bonding material precursor. The conductivity of the bonding material obtained by firing the bonding material precursor can be made extremely high.

  The technology disclosed in the present specification can be realized in various forms, for example, a bonding material precursor, an air electrode bonded by a bonding material formed by the bonding material precursor, and a current collector. Realized in the form of an electrochemical reaction unit (fuel cell power generation unit or electrolytic cell unit) including members, an electrochemical reaction cell stack (fuel cell stack or electrolytic cell stack) including a plurality of electrochemical reaction units, and a manufacturing method thereof Is possible.

1 is a perspective view showing an external configuration of a fuel cell stack 100 in the present 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. 4 is a flowchart showing a method for manufacturing the fuel cell stack 100 in the present embodiment. It is explanatory drawing which shows the manufacturing method of the joining layer 138 in this embodiment. It is explanatory drawing which shows the result of the performance evaluation of the joining layer 138. It is explanatory drawing which shows the manufacturing method of the joining layer 138 in a comparative example.

A. Embodiment:
A-1. Constitution:
(Configuration of fuel cell stack 100)
FIG. 1 is a perspective view showing an external configuration of a fuel cell stack 100 in the present embodiment, and FIG. 2 is an explanatory diagram showing an XZ cross-sectional configuration of the fuel cell stack 100 at a position II-II in FIG. 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. 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. It may be installed. The same applies to FIG.

  The fuel cell stack 100 includes a plurality of (seven in this embodiment) 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.

  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 into 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 into which the bolts 22B are inserted has an oxidant off-gas OOG that is a 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) located at the position and the communication hole 108 into 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 for 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 into 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.

  As shown in FIGS. 4 and 5, the power generation unit 102 that is the minimum unit of power generation includes a single cell 110, a separator 120, an air electrode side frame 130, an air electrode side current collector 134, and a fuel electrode side frame. 140, a fuel electrode side current collector 144, and a pair of interconnectors 150 constituting the uppermost layer and the lowermost layer of the power generation unit 102. A hole corresponding to the above-described communication hole 108 into which the bolt 22 is inserted is formed in the peripheral portion around the Z direction in the separator 120, the air electrode side frame 130, the fuel electrode side frame 140, and the interconnector 150.

  The interconnector 150 is a substantially rectangular flat plate-shaped conductive member, and is formed of a metal containing Cr (chromium) such as ferritic stainless steel, for example. 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 unit cell 110 includes an electrolyte layer 112, and an air electrode (cathode) 114 and a fuel electrode (anode) 116 that face each other in the vertical direction (the arrangement direction in which the power generation units 102 are arranged) with the electrolyte layer 112 interposed therebetween. The single cell 110 of the present embodiment is a fuel electrode-supported single cell that supports the electrolyte layer 112 and the air electrode 114 with the fuel electrode 116.

  The electrolyte layer 112 is a substantially rectangular flat plate-shaped member. For example, YSZ (yttria stabilized zirconia), ScSZ (scandia stabilized zirconia), SDC (samarium doped ceria), GDC (gadolinium doped ceria), perovskite oxide It is formed with solid oxides such as. The air electrode 114 is a substantially rectangular flat plate-shaped member, and is formed of, for example, a perovskite oxide (for example, LSCF (lanthanum strontium cobalt iron oxide), LSM (lanthanum strontium manganese oxide), LNF (lanthanum nickel iron)). Has been. The fuel electrode 116 is a substantially rectangular flat plate-like member, and is formed of, for example, Ni (nickel), cermet made of Ni and ceramic particles, Ni-based alloy, or the like. Thus, 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 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. The single cell 110 to which the separator 120 is bonded is also referred to as a single cell with a separator.

  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. 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 portion of the surface of the separator 120 opposite to the side facing the electrolyte layer 112 and the peripheral edge portion of the surface of the interconnector 150 facing the air electrode 114. . 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.

  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 made 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.

  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.

  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, for example, a metal containing Cr (chromium) such as 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. In the present embodiment, the air electrode side current collector 134 and the interconnector 150 are formed as an integral member. That is, a flat plate-shaped portion perpendicular to the vertical direction (Z-axis direction) of the integral member functions as the interconnector 150 and is formed so as to protrude toward the air electrode 114 from the flat plate-shaped portion. The plurality of current collector elements 135 function as the air electrode side current collector 134. The air electrode side current collector 134 or the integrated member of the air electrode side current collector 134 and the interconnector 150 corresponds to the current collection member in the claims.

As shown in FIGS. 4 and 5, the surface of the air electrode side current collector 134 is covered with a conductive coat 136. The coat 136 is made of, for example, a spinel oxide (for example, MnCo ₂ O ₄ , ZnMn ₂ O ₄ , CuMn ₂ O _4, etc.). The coating 136 is formed on the surface of the air electrode side current collector 134 by a known method such as spray coating, ink jet printing, spin coating, dip coating, plating, sputtering, or thermal spraying. As described above, in the present embodiment, the air electrode side current collector 134 and the interconnector 150 are formed as an integral member. While the interface with the interconnector 150 is not covered with the coat 136, the surface of the interconnector 150 facing at least the flow path of the oxidant gas (that is, the surface on the air electrode 114 side of the interconnector 150) And the surface facing the communication hole 108 constituting the oxidant gas introduction manifold 161 and the oxidant gas discharge manifold 162) are covered with a coat 136. In addition, a chromium oxide film may be formed by heat treatment on the air electrode side current collector 134. In this case, the coat 136 is not the film but the air electrode side current collector 134 on which the film is formed. It is the layer formed so that it might cover. In the following description, unless otherwise specified, the air electrode side current collector 134 (or current collector element 135) means “the air electrode side current collector 134 (or current collector element 135) covered with the coat 136”. To do.

The air electrode 114 and the air electrode side current collector 134 are joined by a conductive joining layer 138. The bonding layer 138 is a fired body containing a spinel-type transition metal composite oxide (eg, MnCo ₂ O ₄ , ZnMn ₂ O ₄ , CuMn ₂ O _4, etc.) having a first metal element and a second metal element. It is. A method for manufacturing the bonding layer 138 will be described in detail later. 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 that the air electrode side current collector 134 is in contact with the surface of the air electrode 114, in the present embodiment, the air electrode side current collector 134 and the air electrode 114 covered with the coat 136. A bonding layer 138 is interposed therebetween. The bonding layer 138 corresponds to the bonding material in the claims.

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 one interconnector 150 through the air electrode side current collector 134 (and the coat 136, the bonding layer 138), and the fuel electrode 116 is a fuel. It is electrically connected to the other interconnector 150 via the pole side current collector 144. 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. Manufacturing method of fuel cell stack 100:
FIG. 6 is a flowchart showing a method for manufacturing the fuel cell stack 100 in the present embodiment. First, a predetermined amount of a spinel-type transition metal composite oxide powder is weighed, and a reduction treatment is performed on the powder, thereby producing a raw material powder for the bonding layer 138 (S110). The reduction treatment refers to heat treatment at 700 ° C. to 900 ° C. in a non-oxidant gas atmosphere or in a vacuum state. As the non-oxidant gas, hydrogen, argon or nitrogen is preferable.

FIG. 7 is an explanatory diagram showing a method for manufacturing the bonding layer 138 in the present embodiment. The structure of the raw material powder of the bonding layer 138 produced in S110 is schematically shown on the left side of FIG. 7, and the structure of the bonding layer 138 formed by firing is schematically shown on the right side of FIG. It is shown. As described above, the bonding layer 138 is a fired body including a spinel-type transition metal composite oxide having a first metal element and a second metal element. In S110, such a spinel-type transition metal is used. Reduction treatment is performed on the composite oxide powder. As shown in FIG. 7, the raw material powder produced by this reduction treatment includes a plurality of first particles P1. Each first particle P1 has a plurality of metal oxide portions Amo made of an oxide of a first metal element and a plurality of metal portions Am made of a second metal element. That is, the first particle P1 includes the second metal element contained in the spinel-type transition metal composite oxide particles before the reduction treatment and the first metal P1 contained in the spinel-type transition metal composite oxide particles. 2 is a secondary particle in which an oxide of one metal element is bonded. For example, when the bonding layer 138 includes MnCo ₂ O ₄ that is a spinel transition metal composite oxide, the metal oxide portion Amo is made of MnO, and the metal portion Am is made of Co.

The raw material powder produced by this reduction treatment includes metal oxide particles (for example, Co ₃ O ₄ particles) composed only of metal element oxides or metal particles composed only of metal elements. There is. However, the number of first particles P1 contained in the raw material powder is larger than the total number of metal oxide particles and metal particles. The metal oxide particles and metal particles correspond to “other particles” in the claims. In this specification, the term “oxide of a metal element” means a compound composed of the metal element and an oxygen element, and a compound containing another metal element different from the metal element (that is, (Metal composite oxide) is not included.

  Next, the raw material powder produced in S110 and the organic substance as the binder are mixed at a predetermined ratio to produce a bonding paste for forming the bonding layer 138 (S120). The relationship that the number of the first particles P1 described above is larger than the total number of metal oxide particles and metal particles is also maintained in the created bonding paste.

  Next, the bonding paste is disposed between the air electrode 114 and the air electrode side current collector 134 constituting each power generation unit 102 of the fuel cell stack 100 by screen printing or the like (S130). The application thickness of the bonding paste is, for example, 20 μm to 50 μm. At this time, the air electrode 114 and the air electrode side current collector 134 may be joined to other members constituting each power generation unit 102.

  In a state where the bonding paste is disposed between the air electrode 114 and the air electrode side current collector 134, a drying process of about 100 ° C. to 200 ° C. is performed, and a heat treatment of about 700 ° C. to 900 ° C. is performed in the atmosphere. (Baking) is performed (S140). Accordingly, the bonding paste becomes a bonding layer 138 that is a fired body that bonds the air electrode 114 and the air electrode side current collector 134. That is, as shown in FIG. 7, the first metal element contained in the metal oxide portion Amo and the second metal contained in the metal portion Am within each first particle P1 and between each first particle P1. Interdiffusion with the element occurs, and a bonding layer 138 that is a fired body including a spinel-type transition metal composite oxide CMO having a first metal element and a second metal element is formed. The state before firing of the bonding layer 138, that is, the bonding paste or the bonding paste dried is also referred to as a “bonding material precursor”.

  Thereafter, the remaining assembly process (for example, fastening of the fuel cell stack 100 with the bolt 22) is performed (S150), and the manufacture of the fuel cell stack 100 having the above-described configuration is completed.

A-4. Performance evaluation of bonding layer 138:
Performance evaluation was performed on the conductivity of the bonding layer 138 that bonds the air electrode 114 and the air electrode side current collector 134 (or an integrated member of the air electrode side current collector 134 and the interconnector 150, the same applies hereinafter). FIG. 8 is an explanatory diagram showing the results of performance evaluation of the bonding layer 138. The performance evaluation was performed using seven types of bonding material precursors manufactured by mixing each of the seven types of raw material powders shown in FIG. 8 with an organic substance. Each bonding material precursor is printed on the surface of the air electrode side current collector 134 with a thickness of 20 μm, a platinum foil is placed on the printed bonding material precursor, and heat treatment (firing) is performed at 850 ° C. for 3 hours. By performing, 7 types of samples (sample 1-7) in which the air electrode side current collector 134 and the platinum foil were joined by the joining layer 138 were manufactured. The bonding layer 138 in any sample is also a fired body including a spinel-type transition metal composite oxide having a first metal element and a second metal element. Conductivity tests were performed on each sample.

In the conductivity test, the conductivity of each sample was measured by the 4-terminal method in an air atmosphere at 850 ° C., and when the measured value was less than 1.6 Ωcm ² , it was determined that the conductivity was high (◯), and the measured value was 1 The electrical conductivity was judged to be low (Δ) when it was 0.6 Ωcm ² or more and less than 2.5 Ωcm ² , and the electrical conductivity was judged to be extremely low (x) when the measured value was 2.5 Ωcm ² or more.

In Sample 1-4 (Example), the raw material powder included in the bonding material precursor is prepared by reducing a spinel-type transition metal composite oxide having a first metal element and a second metal element. It has been done. Specifically, the raw material powder used in Sample 1 is a spinel-type transition metal composite oxide (MnCo ₂ O ₄ ) having Mn (first metal element) and Co (second metal element). It was produced by reduction treatment. Therefore, this raw material powder includes a plurality of metal oxide portions Amo composed of MnO (first metal element oxide) and a plurality of metal portions Am composed of Co (second metal element). A plurality of first particles P1 are provided (see FIG. 7). The particle size of the spinel-type transition metal composite oxide powder, which is the subject of reduction treatment in Sample 1, is 0.1 μm to 2 μm, and the median diameter of the powder is 0.5 μm to 2 μm. surface area of ^{3m 2} / ^g~8m 2 / g, the amount of the powder was 50 g. The same applies to other samples.

In sample 1, when the raw material powder produced by the reduction treatment was crushed with an agate mortar, the powder particle diameter was 0.1 μm to 3 μm, the median diameter was 1 μm to 4 μm, and the specific surface area was 1 m ² / g to 5 m ² / g. When the structure of the powder after pulverization was analyzed using XRD, it was confirmed that most of the powder was reduced to two phases of MnO and Co. However, it was confirmed that trace amounts of metal oxide particles (CoO particles) were also included. The same applies to other samples.

Similarly, the raw material powder used in Sample 2 is a spinel-type transition metal composite oxide (Mn _1.5 Co _1.5 ) having Mn (first metal element) and Co (second metal element). O ₄ ) produced by reduction treatment, and composed of a plurality of metal oxide portions Amo composed of MnO (first metal element oxide) and Co (second metal element). And a plurality of first particles P1 having a plurality of metal portions Am. The raw material powder used in Sample 3 is obtained by reducing spinel-type transition metal composite oxide (CuMn ₂ O ₄ ) having Mn (first metal element) and Cu (second metal element). A plurality of metal oxide portions Amo made of MnO (first metal element oxide) and a plurality of metal portions Am made of Cu (second metal element). A plurality of first particles P1 are provided. The raw material powder used in sample 4 is obtained by reducing spinel-type transition metal composite oxide (ZnMn ₂ O ₄ ) having Mn (first metal element) and Zn (second metal element). A plurality of metal oxide portions Amo made of MnO (first metal element oxide) and a plurality of metal portions Am made of Zn (second metal element). A plurality of first particles P1 are provided.

On the other hand, in Sample 5-7 (Comparative Example), the raw material powder contained in the bonding material precursor is not produced by reducing spinel-type transition metal composite oxide unlike the above embodiment. . Specifically, the raw material powder used in Sample 5 is composed of metal oxide particles composed of MnO (first metal element oxide) and metal particles composed of Co (second metal element). It is a mixed powder. The raw material powder used in Sample 6 is a mixed powder of metal particles composed of Mn (first metal element) and metal particles composed of Co (second metal element). The raw material powder used in Sample 7 is a powder of a spinel type transition metal composite oxide (MnCo ₂ O ₄ ) itself.

  As shown in FIG. 8, Sample 1-4 (Example) was determined to have high conductivity (◯). The bonding material precursor of Sample 1-4 has a plurality of metal oxide portions Amo composed of oxides of the first metal elements and a plurality of metal portions Am composed of the second metal elements. The first particle P1 is included (see FIG. 7). Therefore, in the bonding material precursor, there is little deviation in the arrangement of the metal oxide portion Amo and the metal portion Am, and there are many places where the metal oxide portion Amo and the metal portion Am are in contact. Therefore, during the firing, the first metal element contained in the metal oxide portion Amo and the second metal element contained in the metal portion Am are likely to be interdiffused, and the interdiffusion is completed in a short time and uniform. A bonding layer 138 containing a large number of spinel-type transition metal composite oxides is formed. Since the spinel-type transition metal composite oxide has high conductivity, the formed bonding layer 138 also has high conductivity.

In contrast, Sample 5 (Comparative Example) was determined to have low conductivity (Δ). FIG. 9 is an explanatory view showing a method of manufacturing the bonding layer 138 in the comparative example. In sample 5, as shown in FIG. 9, the bonding material precursor is composed of metal oxide particles P2 composed of MnO (oxide of the first metal element) and Co (second metal element). Metal particles P3. Therefore, in the bonding material precursor, there are many places where the metal oxide particles P2 containing the first metal element are arranged unevenly and places where the metal particles P3 containing the second metal element are arranged unevenly. In other words, in addition to the location B1 where the metal oxide particles P2 and the metal particles P3 are in contact, there are also a number of locations B2 where the metal oxide particles P2 are in contact with each other and locations B3 where the metal particles P3 are in contact with each other. Therefore, at the location B1 where the metal oxide particles P2 and the metal particles P3 are in contact with each other during firing, Mn (first metal element) contained in the metal oxide particles P2 and Co (second metal) contained in the metal particles P3. Although the spinel-type transition metal composite oxide CMO is generated due to mutual diffusion with the metal element), at the location B2 where the metal oxide particles P2 contact each other and the location B3 where the metal particles P3 contact each other, Interdiffusion between the first metal element and the second metal element is less likely to occur, and oxides of single metal elements (for example, Mn ₃ O ₄ and Co ₃ O ₄ ) are mainly generated. Since the oxide of a single metal element has lower conductivity than the spinel type transition metal composite oxide, the conductivity of the formed bonding layer 138 is relatively low. In particular, the tendency is remarkable immediately after firing.

Similarly, Sample 6 (Comparative Example) was also determined to have low conductivity (Δ). The bonding material precursor of the sample 6 has a configuration in which the metal oxide particles P2 are replaced with the metal particles P2 in FIG. 9 described above. That is, the bonding material precursor of sample 6 includes metal particles P2 made of Mn (first metal element) and metal particles P3 made of Co (second metal element). Therefore, in the bonding material precursor, there are a large number of locations where the metal particles P2 containing the first metal element are arranged unevenly and locations where the metal particles P3 containing the second metal element are arranged unevenly. In addition to the location B1 where the metal particles P2 and the metal particles P3 are in contact, there are many locations B2 where the metal particles P2 are in contact with each other, and there are many locations B3 where the metal particles P3 are in contact. Accordingly, at the location B1 where the metal particles P2 and the metal particles P3 are in contact with each other during firing, Mn (first metal element) contained in the metal particles P2 and Co (second metal element) contained in the metal particles P3. Although the spinel-type transition metal composite oxide is generated by the mutual diffusion of the first metal element and the second metal in the portion B2 where the metal particles P2 are in contact with each other and the location B3 where the metal particles P3 are in contact with each other, Interdiffusion with the metal element is less likely to occur, oxides of single metal elements (for example, Mn ₃ O ₄ and Co ₃ O ₄ ) are mainly generated, and the conductivity of the formed bonding layer 138 is relatively low. .

Sample 7 (Comparative Example) was determined to have very low conductivity (x). The bonding material precursor of sample 7 includes a powder of a spinel type transition metal composite oxide (MnCo ₂ O ₄ ) itself. Since the spinel-type transition metal composite oxide is an oxide that exists stably even at a high temperature, sample 7 contains Mn (first metal element) and Co (second metal element) during firing. Interdiffusion hardly occurs. As a result, the area of the contact portion between the particles serving as a conductive path in the formed bonding layer 138 becomes small, and the conductivity of the bonding layer 138 becomes extremely low.

A-5. Effects of this embodiment:
As described above, in this embodiment, the bonding layer 138 that bonds the air electrode 114 and the air electrode side current collector 134 is a spinel transition metal having a first metal element and a second metal element. A bonding material precursor that is a fired body including a composite oxide and is in a state before firing of the bonding layer 138 includes an organic substance, a metal oxide portion Amo composed of an oxide of a first metal element, and a second oxide. And a plurality of first particles P1 each having a metal portion Am made of a metal element. Therefore, in the bonding material precursor, the deviation of the arrangement of the metal oxide portion Amo and the metal portion Am is small, and there are many places where the metal oxide portion Amo and the metal portion Am are in contact with each other. The first metal element contained in the material portion Amo and the second metal element contained in the metal portion Am are likely to be interdiffused, and the interdiffusion is completed in a short time, and a uniform spinel type transition metal composite oxide Is formed. Therefore, according to the bonding material precursor of this embodiment, the conductivity of the bonding layer 138 obtained by firing the bonding material precursor can be increased.

  In particular, in the present embodiment, each first particle P1 included in the bonding material precursor has a plurality of metal oxide portions Amo and a plurality of metal portions Am. There are more places where Amo and the metal portion Am are in contact, and during firing, the first metal element contained in the metal oxide portion Amo and the second metal element contained in the metal portion Am are more interdiffused. Since the bonding layer 138 which is likely to occur and contains a larger amount of the uniform spinel transition metal composite oxide is formed, the conductivity of the bonding layer 138 can be further increased.

  In the present embodiment, the first metal element is Mn, and the second metal element is any one of Co, Cu, and Zn. Such a spinel-type transition metal composite oxide having the first metal element and the second metal element has a relatively high conductivity. Therefore, according to this configuration, the conductivity of the bonding layer 138 obtained by firing the bonding material precursor can be extremely increased.

  In this embodiment, the raw material powder of the bonding material precursor is produced by reducing the spinel type transition metal composite oxide having the first metal element and the second metal element. In this way, the majority of the plurality of particles contained in the raw material powder has a metal oxide portion constituted by the oxide of the first metal element and a metal portion constituted by the second metal element. Therefore, the conductivity of the bonding layer 138 obtained by firing the bonding material precursor can be increased.

A-6. Analysis method of bonding material precursor:
The analysis method of the bonding material precursor is, for example, as follows. The bonding material precursor containing the raw material powder and the organic substance is subjected to ultrasonic cleaning (38 kHz, 5 min) in ethanol, and then dried (100 ° C., 30 min). After mirror fabrication and mirror polishing, an element map is created by EDS. In this case, the field of view is set to 5000 times, and the observation is made with the aim of a position where the powder particles do not overlap vertically. For example, when the bonding material precursor used in Sample 1 for performance evaluation was analyzed by this method, MnO (first metal element) was formed using a metal portion Am composed of Co (second metal element) as a nucleus. It was confirmed that the metal oxide portion Amo composed of the oxide was disposed around.

B. Variations:
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.

  In the above embodiment, the first metal element contained in the spinel-type transition metal composite oxide is Mn, and the second metal element is any one of Co, Cu, and Zn. The first and second metal elements contained in the transition metal composite oxide may be metal elements other than those described above. However, as described above, if the first metal element is Mn and the second metal element is any one of Co, Cu, and Zn, the conductivity of the bonding layer 138 formed by firing the bonding material precursor. Can be increased, which is preferable. Further, the spinel-type transition metal composite oxide may contain other metal elements in addition to the first and second metal elements.

  Moreover, in the said embodiment, the 1st particle | grains P1 contained in a joining material precursor were comprised with the some metal oxide part Amo comprised by the oxide of the 1st metal element, and the 2nd metal element. Although it has the plurality of metal portions Am, the first particles P1 may have one metal oxide portion Amo and one metal portion Am.

  In the above embodiment, the number of the first particles P1 included in the bonding material precursor is greater than the total number of metal oxide particles and metal particles included in the bonding material precursor, but this is not necessarily the case. There is no need. The bonding material precursor may not include at least one of metal oxide particles and metal particles.

  In the above embodiment, the spinel-type transition metal composite oxide is reduced to produce the raw material powder containing the first particles P1, but the production method of the raw material powder is limited to this. Absent. For example, the raw material powder containing the first particles P1 may be produced by depositing particles of the second metal element on the oxide of the first metal element by CVD or PVD.

  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.

  Moreover, in the said embodiment, although the space between the outer peripheral surface of the axial part of each bolt 22 and the inner peripheral surface of each communicating hole 108 is utilized as each manifold, it replaces with this and the axis | shaft of each bolt 22 is used. An axial hole may be formed in the part, and the hole may be used as each manifold. Further, each manifold may be provided separately from each communication hole 108 into which each bolt 22 is inserted.

  In the above 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. Two power generation units 102 may be provided with respective interconnectors 150. In the above embodiment, the upper interconnector 150 of the uppermost power generation unit 102 in the fuel cell stack 100 and the lower interconnector 150 of the lowermost power generation unit 102 are omitted. These interconnectors 150 may be provided without being omitted.

  In the above embodiment, the air electrode side current collector 134 and the interconnector 150 adjacent thereto may be separate members. Further, in the above embodiment, the fuel electrode side current collector 144 may have the same configuration as the air electrode side current collector 134, and the fuel electrode side current collector 144 and the adjacent interconnector 150 are an integral member. It may be. Further, the fuel electrode side frame 140 instead of the air electrode side frame 130 may be an insulator. The air electrode side frame 130 and the fuel electrode side frame 140 may have a multilayer structure.

  Moreover, the material which forms each member in the said embodiment is an illustration to the last, and each member may be formed with another material. For example, in the above embodiment, the air electrode side current collector 134 is formed of a metal containing Cr, but the air electrode side current collector 134 may be formed of other materials. In addition, the shape of each current collector element 135 constituting the air electrode side current collector 134 is not limited to a rectangular column shape, and may be another shape. Further, the air electrode side current collector 134 may not be covered with the coat 136.

  In the above embodiment, the city gas is reformed to obtain the hydrogen-rich fuel gas FG, but the fuel gas FG may be obtained from other raw materials such as LP gas, kerosene, methanol, gasoline, Pure hydrogen may be used as the fuel gas FG.

  In the present specification, the fact that the member B and the member C are opposed to each other across the member (or a part having the member, the same applies hereinafter) A is not limited to the form in which the member A and the member B or the member C are adjacent to each other. It includes a form in which another component is interposed between member A and member B or member C. For example, even in a configuration in which another layer is provided between the electrolyte layer 112 and the air electrode 114, it can be said that the air electrode 114 and the fuel electrode 116 face each other with the electrolyte layer 112 interposed therebetween.

  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 minimum 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 electrolytic cell stack is well known as described in, for example, Japanese Patent Application Laid-Open No. 2014-207120, and thus will not be described in detail here. It is a configuration. That is, the fuel cell stack 100 in the above-described embodiment may be read as an electrolytic cell stack, and the power generation unit 102 may be read as an electrolytic cell unit. 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, the bonding layer 138 for bonding the air electrode 114 and the air electrode side current collector 134 is formed of the first metal element and the second electrode, as in the above embodiment. And a bonding material precursor, which is a state before the bonding layer 138 is fired, is composed of an organic substance and an oxide of the first metal element. If a configuration including a plurality of first particles each having a formed metal oxide portion and a metal portion composed of a second metal element is employed, bonding formed by firing the bonding material precursor The conductivity of the layer 138 can be increased.

In the above embodiment, the solid oxide fuel cell (SOFC) has been described as an example. However, the present invention relates to a solid polymer fuel cell (PEFC), a phosphoric acid fuel cell (PAFC), a molten carbonate type. It can also be applied to other types of fuel cells (or electrolysis cells) such as fuel cells (MCFC).

  Moreover, although the said embodiment demonstrated the joining material precursor which is the state before baking of the joining layer 138 which joins the air electrode 114 and the air electrode side collector 134 in a fuel cell (or electrolysis cell) as an example. The present invention is not limited to the bonding of the air electrode 114 and the air electrode side current collector 134, but is a bonding state before firing the bonding material for bonding the first conductive member and the second conductive member. Applicable to general material precursors. For example, the invention of the present application is a bonding material precursor in a state before firing of a bonding material for bonding the fuel electrode 116 as the first conductive member and the fuel electrode side current collector 144 as the second conductive member. It is applicable to.

22: Bolt 24: Nut 26: Insulating sheet 27: Gas passage member 28: Body portion 29: Branch portion 100: Fuel cell stack 102: 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 electrode side Current collector 135: Current collector element 136: Coat 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 Opposing part 146: Interconnector facing part 147: Connecting part 149: Spare Sir 150: interconnector 161: oxidizing gas inlet manifold 162: oxidizing gas discharging manifold 166: an air chamber 171: fuel gas inlet manifold 172: fuel gas discharging manifold 176: fuel chamber

Claims (10)

A conductive joint comprising a spinel-type transition metal composite oxide having a first metal element and a second metal element, and joining the first conductive member and the second conductive member A bonding material precursor in a state before firing the material,
Organic matter,
A plurality of first particles each having a metal oxide portion constituted by an oxide of the first metal element and a metal portion constituted by the second metal element, Bonding material precursor. In the bonding material precursor according to claim 1,
Each said 1st particle | grain has a some said metal oxide part and a some said metal part, The joining material precursor characterized by the above-mentioned. In the bonding material precursor according to claim 1 or 2,
The number of the first particles is larger than the number of other particles which are at least one of the metal oxide particles composed only of the metal oxide portion and the metal particles composed only of the metal portion. And a bonding material precursor. In the bonding material precursor according to any one of claims 1 to 3,
The bonding material precursor, wherein the first metal element is Mn, and the second metal element is any one of Co, Cu, and Zn. In the bonding material precursor according to any one of claims 1 to 4,
The first conductive member is the air electrode in an electrochemical reaction unit cell including an electrolyte layer containing a solid oxide, and an air electrode and a fuel electrode facing each other with the electrolyte layer interposed therebetween. And a bonding material precursor. In the bonding material precursor according to claim 5,
The second conductive member is the current collecting member in an electrochemical reaction unit comprising the electrochemical reaction single cell and a current collecting member disposed on the air electrode side of the electrochemical reaction single cell. A bonding material precursor characterized by comprising: An electrochemical reaction cell stack comprising a plurality of electrochemical reaction units,
Each of the electrochemical reaction units is
An electrochemical reaction unit cell including an electrolyte layer containing a solid oxide, and an air electrode and a fuel electrode facing each other across the electrolyte layer;
A current collecting member disposed on the air electrode side of the electrochemical reaction unit cell,
The said cathode and said current collection member as said 2nd electroconductive member as said 1st electroconductive member are based on the joining material precursor as described in any one of Claim 1- Claim 6. An electrochemical reaction cell stack characterized by being bonded by the formed bonding material. A conductive joint comprising a spinel-type transition metal composite oxide having a first metal element and a second metal element, and joining the first conductive member and the second conductive member A method for producing a bonding material precursor in a state before firing the material,
Producing a raw material powder by reducing a spinel-type transition metal composite oxide having the first metal element and the second metal element;
Mixing the raw material powder and an organic material to produce the bonding material precursor;
A method for producing a bonding material precursor. In the manufacturing method of the joining material precursor according to claim 8,
The method for producing a bonding material precursor, wherein the first metal element is Mn, and the second metal element is any one of Co, Cu, and Zn. An electrochemical reaction unit cell including an electrolyte layer containing a solid oxide and an air electrode and a fuel electrode facing each other across the electrolyte layer, and a current collector disposed on the air electrode side of the electrochemical reaction unit cell A method for producing an electrochemical reaction cell stack comprising a plurality of electrochemical reaction units comprising:
Preparing the bonding material precursor manufactured by the method for manufacturing a bonding material precursor according to claim 8 or 9,
Disposing the bonding material precursor between the air electrode as the first conductive member and the current collecting member as the second conductive member;
Forming the bonding material for bonding the air electrode and the current collecting member by firing the bonding material precursor;
A method for producing an electrochemical reaction cell stack, comprising:

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