JP2018032578A - Method for manufacturing electrochemical reaction cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture an electrochemical reaction cell which is reduced in fluctuation (reduction) in electrochemical reactive performance during operation while suppressing the worsening of gas diffusibility of an air electrode.SOLUTION: A method for manufacturing an electrochemical reaction cell in which at least one of an electrolyte layer and a fuel electrode includes partially stabilized Zr comprises the steps of: preparing an electrolyte layer precursor 112X, a fuel electrode precursor 116X and an intermediate layer precursor 300X; performing a first thermal treatment on the electrolyte layer precursor, the fuel electrode precursor and the intermediate layer precursor at a temperature equal to or higher than a phase transition temperature of the partially stabilized Zr, thereby forming a laminate 410 of the electrolyte layer, the fuel electrode and an intermediate layer; performing a second thermal treatment on the laminate at a temperature lower than the phase transition temperature for 10 hours or longer time; and performing a third thermal treatment on the laminate 420 subjected to the second thermal treatment and an air electrode precursor 114X at a temperature lower than the phase transition temperature, thereby forming the electrochemical reaction cell 110.SELECTED DRAWING: Figure 7

Description

  The technology disclosed in this specification relates to a method for manufacturing an electrochemical reaction cell.

  A solid oxide fuel cell (hereinafter referred to as “SOFC”) is known as one type of fuel cell that generates electricity using an electrochemical reaction between hydrogen and oxygen. A fuel cell single cell (hereinafter referred to as “single cell”) constituting the SOFC includes an electrolyte layer containing a solid oxide and air facing each other in a predetermined direction (hereinafter referred to as “array direction”) across the electrolyte layer. And at least one of the electrolyte layer and the fuel electrode includes partially stabilized Zr.

  In a single cell, in order to suppress a decrease in power generation performance due to a reaction between a substance contained in the air electrode and a substance contained in the electrolyte layer to form a high resistance layer, the air electrode and the electrolyte layer A technique for arranging an intermediate layer between them is known (for example, see Patent Document 1). The intermediate layer suppresses the formation of the high resistance layer by suppressing the diffusion of the substance that is the generation source of the high resistance layer from the air electrode to the electrolyte layer.

  A conventional method for manufacturing a single cell having an intermediate layer as described above is as follows. That is, by subjecting the electrolyte layer precursor, the fuel electrode precursor, and the intermediate layer precursor to a heat treatment at a temperature higher than the phase transition temperature of the partially stabilized Zr, a laminate of the electrolyte layer, the fuel electrode, and the intermediate layer is obtained. Form. Here, the higher the heat treatment temperature, the higher the density of the intermediate layer in the laminate. The higher the density of the intermediate layer, the higher the ability to suppress the diffusion of the substance that is the source of the high resistance layer from the air electrode to the electrolyte layer. For this reason, in general, the heat treatment for forming the intermediate layer is performed at a temperature higher than the phase transition temperature of the partially stabilized Zr. Next, a single cell is manufactured by performing a heat treatment at a temperature lower than the phase transition temperature on the laminate and the air electrode precursor.

JP 2012-181928 A

The single cell manufactured by the above-described conventional manufacturing method has a problem that fluctuation (decrease) in power generation performance during operation is large. That is, in the conventional manufacturing method described above, when forming the intermediate layer, the crystal system of the partially stabilized Zr is changed from a tetragonal crystal having low oxygen ion conductivity by heat treatment at a temperature higher than the phase transition temperature of the partially stabilized Zr. Phase transition to cubic crystals with high oxygen ion conductivity. Thereafter, when the air electrode is formed, heat treatment at a temperature lower than the phase transition temperature is performed for about 4 hours. However, many partially stabilized Zr crystal systems contained in the electrolyte layer remain cubic and do not undergo phase transition. On the other hand, the operating temperature of the SOFC provided with the single cell is generally lower than the phase transition temperature. For this reason, when the SOFC is operated for a long time, the crystal system of many partially stabilized Zr contained in the electrolyte layer of the single cell changes from a cubic crystal having a high oxygen ion conductivity to a tetragonal crystal having a low oxygen ion conductivity. Metastasize. Thereby, the problem that the fluctuation | variation of the electric power generation performance of the single cell at the time of a driving | operation arises. In addition, if the fluctuation in the power generation performance of the single cell during operation is large, there arises a problem that the operation control of the SOFC becomes complicated, for example, the change of the operation condition of the SOFC according to the fluctuation in the power generation performance.

  Such a problem is also a problem common to a method of manufacturing a single cell including a fuel electrode including a partially stabilized Zr and an intermediate layer. Further, it is a common problem in a method of manufacturing a solid oxide electrolytic cell (hereinafter referred to as “SOEC”) that generates hydrogen using an electrolysis reaction of water. In this specification, the fuel cell unit cell and the electrolysis cell are collectively referred to as an electrochemical reaction unit cell.

  The present specification discloses a technique capable of solving at least a part of the problems described above.

  The technology disclosed in this specification can be implemented as the following forms.

(1) An electrochemical reaction cell manufacturing method disclosed in the present specification includes an electrolyte layer containing a solid oxide, an air electrode and a fuel electrode facing each other in a first direction across the electrolyte layer, In the method for producing an electrochemical reaction cell, an electrolyte layer precursor, comprising: an electrolyte layer; and an intermediate layer disposed between the air electrode, wherein at least one of the electrolyte layer and the fuel electrode includes partially stabilized Zr. Body, fuel electrode precursor, and intermediate layer precursor, and the electrolyte layer precursor, fuel electrode precursor, and intermediate layer precursor at a temperature equal to or higher than the phase transition temperature of the partially stabilized Zr. Performing the first heat treatment to form a laminate of the electrolyte layer, the fuel electrode, and the intermediate layer, and subjecting the laminate to a second heat treatment at a temperature lower than the phase transition temperature. A step of performing for more than an hour and the second heat In said stack and the air electrode precursor after physical, by performing the third heat treatment lower than the phase transition temperature, and a step of forming the electrochemical reaction cell. According to the method for manufacturing an electrochemical reaction cell, the first heat treatment at a temperature equal to or higher than the phase transition temperature of the partially stabilized Zr (zirconia) is performed on the electrolyte layer precursor, the fuel electrode precursor, and the intermediate layer precursor. The intermediate layer can be made dense. On the other hand, by the first heat treatment, the partially stabilized Zr crystal system undergoes a phase transition from a tetragonal crystal having a low oxygen ion conductivity to a cubic crystal having a high oxygen ion conductivity. However, after that, the laminated body is subjected to the second heat treatment at a temperature lower than the phase transition temperature for 10 hours or more, so that the crystal system of the partially stabilized Zr changes from cubic to tetragonal. The laminated body and the air electrode precursor after the second heat treatment are subjected to a third heat treatment at a temperature lower than the phase transition temperature, whereby the crystal system of the partially stabilized Zr sufficiently includes tetragonal crystals. A reaction cell is formed. And by performing 2nd heat processing before formation of an air electrode, the fall of the gas diffusibility of the air electrode by progress of sintering of an air electrode precursor can be suppressed. As a result, it is possible to manufacture an electrochemical reaction cell in which fluctuation (decrease) in electrochemical reaction performance during operation is reduced while suppressing a decrease in gas diffusibility of the air electrode.

(2) In the method for manufacturing an electrochemical reaction cell, the time for performing the third heat treatment may be shorter than the time for performing the second heat treatment. According to the manufacturing method of this electrochemical reaction cell, the fall of the gas diffusibility of an air electrode can be suppressed more reliably.

  The technology disclosed in the present specification can be realized in various forms, for example, a fuel cell single cell, a fuel cell stack including a plurality of fuel cell single cells, and a power generation module including a fuel cell stack. A fuel cell system including a power generation module, an electrolysis cell unit, an electrolysis cell stack including a plurality of electrolysis cell units, a hydrogen generation module including an electrolysis cell stack, a hydrogen generation system including a hydrogen generation module, a manufacturing method thereof, and the like It can be realized in the form.

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. 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. 5 is a flowchart showing an example of a method for manufacturing the fuel cell stack 100 in the present embodiment. It is explanatory drawing which shows the outline | summary of the manufacturing method of the single cell 110 in the manufacturing method of the fuel cell stack 100 in this embodiment. It is explanatory drawing which shows the result of the performance evaluation about each sample.

A. First 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. However, the fuel cell stack 100 is actually different from such an orientation. It may be installed. The same applies to FIG.

  The fuel cell stack 100 includes a plurality 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, for example, ferritic stainless steel. 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, an air electrode (cathode) 114 and a fuel electrode (anode) 116 facing each other in the vertical direction (an arrangement direction in which the power generation units 102 are arranged) across the electrolyte layer 112, and the electrolyte layer 112. And an intermediate layer 300 disposed between the air electrode 114 and the air electrode 114. The single cell 110 of this embodiment is a fuel cell-supported single cell in which the fuel electrode 116 supports the electrolyte layer 112, the intermediate layer 300, and the air electrode 114. The single cell 110 corresponds to the electrochemical reaction cell in the claims.

  The electrolyte layer 112 is a substantially rectangular flat plate-shaped member and includes at least partially stabilized Zr. For example, YSZ (yttria stabilized zirconia), ScSZ (scandia stabilized zirconia), CaSZ (calcia stabilized zirconia), and the like. The solid oxide is formed. By performing heat treatment above the phase transition temperature, the partially stabilized Zr crystal system undergoes a phase transition from tetragonal (tetra) with low oxygen ion conductivity to cubic (cubic) with high oxygen ion conductivity, By performing heat treatment below the transition temperature for a predetermined time or longer, the partially stabilized Zr crystal system undergoes a phase transition from a cubic crystal having a high oxygen ion conductivity to a tetragonal crystal having a low oxygen ion conductivity. For example, according to "Masatomo Yashima", two others, Solid State lonics, (Netherlands), Elsevier BV, 1996, volume 86-88, p. 1131, an 8YSZ solid electrolyte layer The phase transition temperature of the partially stabilized Zr contained is 1200 (° C.). 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 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 intermediate layer 300 is a substantially rectangular flat plate-shaped member, and is formed of, for example, a solid oxide such as GDC (gadolinium-doped ceria). The intermediate layer 300 is a metal element (for example, Sr or La, hereinafter also referred to as “diffusion element”) and electrolyte contained in the air electrode 114 under a high temperature condition such as during the operation of the fuel cell stack 100. It functions as a reaction preventing layer that suppresses formation of a high resistance layer (for example, SrZrO ₃ ) by reaction with a transition element (for example, Zr) included in the layer 112. Since the intermediate layer 300 has ion conductivity, the intermediate layer 300 also has a function of moving oxide ions generated by the ionization reaction of oxygen molecules contained in the oxidant gas OG to the electrolyte layer 112 in the air electrode 114.

  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 current collector elements 135 having a substantially quadrangular prism shape, and is formed of, for example, ferritic stainless steel. The air electrode side current collector 134 is in contact with the surface of the air electrode 114 opposite to the side facing the electrolyte layer 112 and the surface of the interconnector 150 facing the air electrode 114. However, as described above, since the power generation unit 102 located at the top in the fuel cell stack 100 does not include the upper interconnector 150, the air electrode side current collector 134 in the power generation unit 102 includes the upper end plate. 104 is in contact. Since the air electrode side current collector 134 has such a configuration, the air electrode 114 and the interconnector 150 (or the end plate 104) are electrically connected. The air electrode side current collector 134 and the interconnector 150 may be formed as an integral member.

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 via the air electrode side current collector 134, and the fuel electrode 116 is connected via the fuel electrode side current collector 144. The other interconnector 150 is electrically connected. 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 startup until the high temperature can be maintained by heat generated by 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 an example of a method for manufacturing the fuel cell stack 100 in the present embodiment. Moreover, FIG. 7 is explanatory drawing which shows the outline | summary of the manufacturing method of the single cell 110 in the manufacturing method of the fuel cell stack 100 in this embodiment.

  As shown in FIG. 6, first, a heat treatment A at a temperature equal to or higher than the phase transition temperature of the partially stabilized Zr contained in the electrolyte layer 112 (hereinafter sometimes simply referred to as “phase transition temperature T (0)”) is performed. The first laminated body of the electrolyte layer 112 and the fuel electrode 116 is formed by firing the electrolyte layer precursor and the fuel electrode precursor (S110). For example, a slurry is prepared by adding a butyral resin, dioctyl phthalate (DOP), which is a plasticizer, a dispersant, and a mixed solvent of toluene and ethanol to a YSZ powder, and mixing them with a ball mill. The obtained slurry is made into a thin film by a doctor blade method to prepare, for example, a green sheet 112X (electrolyte layer precursor) for an electrolyte layer having a thickness of about 10 (μm). Further, NiO powder is weighed so as to be 55 parts by mass in terms of Ni weight, and mixed with 45 parts by mass of YSZ powder to obtain a mixed powder. To this mixed powder, a butyral resin, DOP as a plasticizer, a dispersant, and a mixed solvent of toluene and ethanol are added and mixed in a ball mill to prepare a slurry. The obtained slurry is made into a thin film by a doctor blade method to prepare, for example, a fuel electrode green sheet 116X (fuel electrode precursor) having a thickness of 270 (μm). Then, as shown in <State 1> in FIG. 7, the electrolyte layer green sheet 112X and the fuel electrode green sheet 116X are attached and dried. Thereafter, as the heat treatment A, the electrolyte layer green sheet 112X and the fuel electrode green sheet 116X attached to each other are fired at a temperature T (1) (for example, 1200 (° C.) to 1400 (° C.)), whereby the electrolyte is obtained. A first stacked body 410 of the layer 112 and the fuel electrode 116 is obtained. Since the temperature T (1) is equal to or higher than the phase transition temperature T (0), the heat treatment A changes the crystal system of the partially stabilized Zr from a tetragonal crystal having a low oxygen ion conductivity to a cubic crystal having a high oxygen ion conductivity. Phase transition. The temperature T (1) in the heat treatment A means a temperature in a substantially constant temperature stage, not in the temperature raising stage and the temperature lowering stage. The same applies to the heat treatments B to D.

  Next, the intermediate layer 300 is formed in the first laminate 410 by firing the intermediate layer precursor by performing the heat treatment B at a temperature equal to or higher than the phase transition temperature T (0), and the electrolyte layer 112 and A second stacked body 420 of the fuel electrode 116 and the intermediate layer 300 is formed (S120). More specifically, for example, a solvent composed of an acrylic binder and isopropyl alcohol is added to and mixed with GDC powder to prepare an intermediate layer forming slurry 300X (intermediate layer precursor). Then, as shown in <State 2> in FIG. 7, the prepared intermediate layer forming slurry 300X is applied to the surface on the electrolyte layer 112 side of the first laminate by a screen printing method. Then, the laminated body after application is fired at a temperature T (2) (for example, 1200 (° C.) to 1400 (° C.)), and as shown in <State 3> in FIG. 7, the electrolyte layer 112 and the fuel electrode A second stacked body 420 of 116 and the intermediate layer 300 is obtained. Thus, the denseness of the intermediate layer 300 can be improved by firing the laminated body after application at a high temperature equal to or higher than the phase transition temperature T (0). Further, since the temperature T (2) is equal to or higher than the phase transition temperature T (0), even after the heat treatment B, the crystal system of the partially stabilized Zr remains a cubic crystal and does not undergo phase transition. Note that the temperature T (2) may be the same as the above-described temperature T (1), or may be a different temperature as long as the temperature is equal to or higher than the phase transition temperature T (0). The heat treatment A and the heat treatment B correspond to the first heat treatment in the claims, and the second stacked body 420 corresponds to the stacked body in the claims.

  Next, heat treatment C at a temperature lower than the phase transition temperature T (0) is performed on the second stacked body 420 for 10 hours or longer (S130). More specifically, the heat treatment C at a temperature T (3) (for example, 1000 (° C.) to 1100 (° C.)) is continuously performed on the second stacked body 420 for 10 (hours) or more. Thereby, the crystal system of at least a part (for example, about 10% or more) of the partially stabilized Zr included in the electrolyte layer 112 is changed from a cubic crystal having a high oxygen ion conductivity to a tetragonal crystal having a low oxygen ion conductivity. Can be transferred.

  Next, by performing the heat treatment D at a temperature lower than the phase transition temperature T (0), the air electrode precursor is fired to form the air electrode 114 in the second stacked body 420, and the single cell 110 is formed. Manufacture (S140). More specifically, for example, LSCF powder, alumina powder, polyvinyl alcohol as an organic binder, and butyl carbitol as an organic solvent are mixed, the viscosity is adjusted, and the air electrode paste 114X is prepared. Then, as shown in <State 4> of FIG. 7, the adjusted air electrode paste 114X is applied to the surface on the intermediate layer 300 side of the second stacked body 420 by, for example, screen printing and dried. In addition, as a coating method of the 2nd laminated body 420, other methods, such as spray coating, are also employable. Thereafter, as the heat treatment D, the applied air electrode paste 114X is fired at a temperature T (4) lower than the phase transition temperature T (0) (for example, 950 (° C.) to 980 (° C.)), thereby FIG. As shown in <State 5>, the air electrode 114 is formed on the electrolyte layer 112 side of the second stacked body 420, and the single cell 110 is manufactured. The heat treatment D corresponds to the third heat treatment in the claims.

  A plurality of single cells 110 are manufactured by the above-described manufacturing method, and an assembly process of assembling the manufactured single cells 110 and other members is performed (S150). Through the above steps, the fuel cell stack 100 having the above-described configuration is manufactured.

A-4. Performance evaluation of each sample:
Each performance evaluation performed using a plurality of samples 1 to 8 manufactured by each of a plurality of manufacturing methods having different manufacturing conditions and manufacturing processes will be described. In the performance evaluation for each sample, the fuel cell stack 100 having the above-described configuration was assembled for each of the plurality of samples 1 to 8, and the durability deterioration rate (power generation deterioration rate) was measured. FIG. 8 is an explanatory diagram showing the results of performance evaluation for each sample.

(About sample)
Samples 1 to 6 are manufactured by the manufacturing method shown in FIG. 6 described above, and Samples 7 and 8 are manufactured by a manufacturing method different from the manufacturing method shown in FIG. 6 mainly in that heat treatment C is not performed. It is a thing.
(Sample 1)
In the manufacturing method of Sample 1, the temperature T (1) of the heat treatment A and the temperature T (2) of the heat treatment B are 1205 (° C.), the temperature T (3) of the heat treatment C is 1100 (° C.), and the heat treatment C Execution time is 10 (hours).
(Sample 2)
In the manufacturing method of Sample 2, the temperature T (1) of the heat treatment A, the temperature T (2) of the heat treatment B, and the temperature T (3) of the heat treatment C are the same as those of the sample 1, but the execution time of the heat treatment C is 50 (Time), longer than sample 1.
(Sample 3)
In the manufacturing method of sample 3, the temperature T (1) of heat treatment A, the temperature T (2) of heat treatment B, and the temperature T (3) of heat treatment C are the same as in sample 1, but the execution time of heat treatment C is 100. (Time), which is longer than samples 1 and 2.

(Sample 4)
In the manufacturing method of Sample 4, the temperature T (1) of the heat treatment A and the temperature T (2) of the heat treatment B are the same as those of the sample 1, but the temperature T (3) of the heat treatment C is 1000 (° C.). It is lower than Samples 1 to 3, and the execution time of the heat treatment C is 25 (hours), which is longer than Sample 1.
(Sample 5)
In the manufacturing method of sample 5, the temperature T (1) of heat treatment A and the temperature T (2) of heat treatment B are the same as those of sample 1, and the temperature T (3) of heat treatment C is the same as that of sample 4. However, the execution time of the heat treatment C is 125 (hours), which is longer than the samples 1 to 4.
(Sample 6)
In the manufacturing method of sample 6, the temperature T (1) of heat treatment A and the temperature T (2) of heat treatment B are the same as those of sample 1, and the temperature T (3) of heat treatment C is the same as that of sample 4. However, the execution time of the heat treatment C is 240 (hours), which is longer than the samples 1 to 5.

(Sample 7)
In the manufacturing method of the sample 7, the temperature T (1) of the heat treatment A and the temperature T (2) of the heat treatment B are 1100 (° C.), which is lower than those of the samples 1 to 5, and after the heat treatments A and B are performed, The heat treatment D is performed without performing the heat treatment C.
(Sample 8)
In the manufacturing method of Sample 8, the temperature T (1) of the heat treatment A and the temperature T (2) of the heat treatment B are the same as those of the sample 1, but, similar to the sample 7, the heat treatment C is performed after the heat treatments A and B are performed. Heat treatment D is performed without executing.

(Performance evaluation method)
First, the density of the intermediate layer 300 was evaluated based on the porosity of the intermediate layer 300 (GDC) for the fuel cell stack 100 manufactured by the manufacturing method of each sample 1-8. The porosity of the intermediate layer 300 is specified as follows. Cross sections of the power generation unit 102 that are orthogonal to the oxidant gas flow direction are set at three positions along the oxidant gas flow direction (X-axis direction in the present embodiment as shown in FIG. 2). SEM images (500 times) showing the intermediate layer 300 are obtained at these three locations. That is, nine SEM images are obtained. In each obtained SEM image, a plurality of lines orthogonal to the direction in which the power generation units 102 are arranged (Z-axis direction in the present embodiment) are drawn at a predetermined interval (for example, 1 to 5 μm interval). The length of the portion corresponding to the pores on each straight line is measured, and the ratio of the total length of the portions corresponding to the pores to the total length of the straight line is defined as the porosity on the line. Let the average value of the porosity in the some straight line drawn by the intermediate | middle layer 300 be the porosity of the intermediate | middle layer 300 in the SEM image. For the intermediate layer 300, the final porosity is obtained by taking the average value of the porosity determined in the nine SEM images.

Moreover, the phase transition peak intensity ratio of the partially stabilized Zr in the electrolyte layer 112 was evaluated for the fuel cell stack 100 manufactured by the manufacturing method of each sample 1-8. The phase transition peak intensity ratio is, for example, “Taro Shimonosono”, five others, Solid State lonics, (Netherlands), Elsevier BV, 2012, volume 225, p. 69-72. As measured by Raman spectroscopy. The phase transition peak intensity ratio is such that the partially stabilized Zr crystal system is cubic to tetragonal with respect to the intensity peak attributed to the cubic (600 to 650 cm ⁻¹ ) partially stabilized Zr crystal system included in the electrolyte layer 112. It is the ratio of the intensity peak (250-300 cm < ^-1 >) at the time of phase transition. Therefore, the larger the phase transition peak intensity ratio, the higher the proportion of partially stabilized Zr in which the crystal system has undergone phase transition from cubic to tetragonal.

Moreover, about the fuel cell stack 100 manufactured with the manufacturing method of each sample 1-8, the voltage which performed the electric power generation operation by the current density of 0.55 (A / cm < ² >) after 1000 (hour) electric power generation at 700 (degreeC). (Post-test voltage) was measured, and the ratio of the difference between the initial voltage and the post-test voltage with respect to the initial voltage was calculated as the power generation deterioration rate (%) by the following formula 1.
<Formula 1>
Power generation deterioration rate (%) = (initial voltage−post-test voltage) / initial voltage) × 100
Note that the initial voltage is a current density of 0.55 (A / A) at 700 (° C.) for the fuel cell stack 100 in which rated power generation is performed for 1000 hours or less after shipment in a state where power generation is possible. cm ² ) is a voltage value when the power generation operation is performed.
Further, the post-test voltage refers to power generation at a current density of 0.55 (A / cm 2) at 700 (° C.) for the fuel cell stack 100 that has been rated for 1000 hours after the initial voltage was measured. This is the voltage value after operation.

(About performance evaluation results)
In Samples 1 to 3, the GDC porosity is 20% or less, and the intermediate layer 300 is highly dense. This is considered to be because the temperatures T (1) to T (3) of the heat treatments A to C are relatively high in the manufacturing methods of the samples 1 to 3. In Samples 1 to 3, the longer the execution time of the heat treatment C, the closer the phase transition peak intensity ratio is to 1 and the lower the power generation deterioration rate. That is, under the same temperature condition, the longer the execution time of the heat treatment C, the more the crystal system of partially stabilized Zr undergoes phase transition from cubic to tetragonal, thereby reducing the power generation deterioration rate.

  In samples 4 to 6, the GDC porosity is 22 to 23 (%), and the denseness of the intermediate layer 300 is slightly lower than in samples 1 to 3. This is presumably because the temperature T (3) of the heat treatment C is lower than those of the samples 1 to 3. Sample 4 has the same phase transition peak intensity ratio and power generation deterioration rate as Sample 1, although the execution time of heat treatment C is longer than that of Sample 1. This is because when the temperature T (3) of the heat treatment C is relatively low, in order to obtain the same performance evaluation result as when the temperature T (3) of the heat treatment C is relatively high, the execution time of the heat treatment C This means that it is preferable to make the length relatively long. Accordingly, the temperature T (3) of the heat treatment C is preferably lower than the phase transition temperature and 1000 (° C.) or higher, and further lower than the phase transition temperature and 1100 (° C.) or higher. More preferred. The same applies to the relationship between sample 5 and sample 2 and the relationship between sample 6 and sample 3.

  On the other hand, in the sample 7, the GDC porosity is 45 (%), and the density of the intermediate layer 300 is extremely low as compared with the samples 1 to 6. This is presumably because the temperatures T (1) and T (2) of the heat treatments A and B are lower than those of the samples 1 to 6. Thus, in the sample 7, since the denseness of the intermediate layer 300 is extremely low, the intermediate layer 300 cannot sufficiently exhibit the function as the reaction preventing layer. For this reason, it was difficult to specify the power generation deterioration rate by forming the high resistance layer. In Sample 7, the phase transition peak intensity ratio is 0.905, which is lower than Samples 1-6. This is because the heat treatments A and B were carried out at a temperature lower than the phase transition temperature from the tetragonal crystal to the cubic crystal in the partially stabilized Zr crystal system in the manufacturing method of Sample 7 instead of performing the heat treatment C. The proportion of partially stabilized Zr of crystals is relatively low. In other words, it is not possible to sufficiently obtain partially stabilized Zr whose crystal system is tetragonal, and furthermore, the porosity of the intermediate layer 300 cannot be sufficiently reduced only by firing at a temperature lower than the phase transition temperature. I understand. For this reason, it is considered that in Sample 7, the resistance value was too large to measure the power generation deterioration rate.

  In Sample 8, the GDC porosity is 26 (%), and the intermediate layer 300 is denser than Sample 7. This is presumably because the temperatures T (1) and T (2) of the heat treatments A and B are higher than those of the sample 7. However, in Sample 8, the phase transition peak intensity ratio is 0.900, which is even lower than Sample 7. This is because the proportion of the partially stabilized Zr in which the crystal system has undergone phase transition from tetragonal to cubic by heat treatments A and B by the temperature T (1) T (2) of heat treatments A and B is higher than that of sample 7. This is probably because the heat treatment C is not performed and the proportion of the partially stabilized Zr in which the crystal system remains cubic is high.

A-5. Effects of this embodiment:
According to the manufacturing method of the present embodiment, the electrolyte layer precursor, the fuel electrode precursor, and the intermediate layer precursor are subjected to the heat treatment B at a temperature equal to or higher than the phase transition temperature of the partially stabilized Zr, thereby causing the second lamination. A body 420 is formed, and the intermediate layer 300 of the second stacked body 420 can be made dense. On the other hand, the heat treatment B causes the partially stabilized Zr crystal system to undergo a phase transition from a tetragonal crystal having a low oxygen ion conductivity to a cubic crystal having a high oxygen ion conductivity. However, after that, the second stacked body 420 is subjected to heat treatment C at a temperature lower than the phase transition temperature for 10 hours or more, so that the crystal system of the partially stabilized Zr changes from cubic to tetragonal. The second stacked body 420 and the air electrode precursor after the heat treatment C are subjected to a heat treatment D at a temperature lower than the phase transition temperature, so that a single crystal in which tetragonal crystals are sufficiently contained in the partially stabilized Zr crystal system. A cell 110 is formed. In addition, by performing the heat treatment C before forming the air electrode 114, it is possible to suppress a decrease in gas diffusibility of the air electrode 114 due to the progress of sintering of the air electrode precursor. As a result, it is possible to manufacture the single cell 110 in which fluctuation (decrease) in power generation performance during operation is reduced while suppressing a decrease in gas diffusibility of the air electrode 114. Further, by performing the heat treatment C before the formation of the air electrode 114, the transition metal element (Sr or the like) contained in the air electrode 114 can be transferred to the electrolyte layer 112 side as compared with the case where the heat treatment C is performed simultaneously with the formation of the air electrode 114. Can be prevented from diffusing.

  The execution time of the heat treatment D is preferably shorter than the execution time of the heat treatment C. Thereby, the fall of the gas diffusibility of the air electrode 114 can be suppressed more reliably.

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-described embodiment, the single cell 110 including the electrolyte layer 112 including partially stabilized Zr is exemplified as the electrochemical reaction cell. However, the electrochemical reaction cell is not limited to this, and the fuel electrode including partially stabilized Zr. A single cell may be provided. Specifically, the fuel electrode may be formed of a solid oxide such as YSZ, ScSZ, or CaSZ.

  In the method for manufacturing the fuel cell stack 100 of the above embodiment, the first heat treatment is exemplified by the heat treatment A and the heat treatment B twice. However, the first heat treatment is not limited to this, and the partially stabilized Zr. The heat treatment at a temperature equal to or higher than the phase transition temperature may be performed only once, or may be performed three or more times. In short, the first heat treatment only needs to be performed one or more times at a temperature equal to or higher than the phase transition temperature of the partially stabilized Zr. For example, in the above embodiment, the electrolyte layer green sheet 112X, the fuel electrode green sheet 116X, and the intermediate layer forming slurry 300X may be fired simultaneously.

  In the above embodiment, the intermediate layer 300 composed of one layer is illustrated as the intermediate layer. However, the intermediate layer is not limited to this, and the intermediate layer is composed of a plurality of layers arranged in the vertical direction (Z direction). A layer is also good. Further, the intermediate layer is not limited to one that functions as a reaction preventing layer, and may not function as a reaction preventing layer. Further, the intermediate layer may contain another material in addition to the intermediate layer material having ion conductivity.

  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.

  In the above embodiment, the nuts 24 are fitted on both sides of the bolt 22, but the bolt 22 has a head, and the nut 24 is fitted only on the opposite side of the head of the bolt 22. Also good. Moreover, in the said embodiment, although the volt | bolt 22 is used as a fastening member, the fuel cell stack 100 may be fastened by other fastening members other than the bolt 22.

  In the above embodiment, the end plates 104 and 106 function as output terminals. However, instead of the end plates 104 and 106, separate members (for example, the end plate 104) connected to the end plates 104 and 106, respectively. , 106 and the power generation unit 102) may function as output terminals.

  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. In addition, each manifold may be provided separately from the 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.

  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.

  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 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. 2006-81813, and thus will not be described in detail here. However, it is schematically the same as the fuel cell stack 100 in the above-described embodiment. 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 variation in the electrochemical reaction performance during operation is reduced while suppressing the decrease in the gas diffusibility of the air electrode from the manufacturing method similar to the above embodiment. Electrolytic cell units and the like can be manufactured.

  22: Bolt 24: Nut 26: Insulating sheet 27: Gas passage member 28: Main body 29: Branch 45: Powder 100: Fuel cell stack 102: Power generation unit 104, 106: End plate 108: Communication hole 110: Single cell 112 : Electrolyte layer 112X: Green sheet for electrolyte layer 114: Air electrode 114X: Paste for air electrode 116: Fuel electrode 116X: Green sheet for 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 140: Fuel electrode side frame 141: Hole 142: Fuel gas supply communication hole 143: Fuel gas Discharge communication hole 144: Fuel electrode side current collector 145: Electrode facing portion 146: interconnector facing portion 147: connecting portion 149: spacer 150: interconnector 161: oxidant gas introduction manifold 162: oxidant gas discharge manifold 166: air chamber 171: fuel gas introduction manifold 172: fuel gas discharge manifold 176: fuel Chamber 270: Thickness 300: Intermediate layer 300X: Intermediate layer forming slurry 410: Laminate 420: Laminate FG: Fuel gas FOG: Fuel off gas OG: Oxidant gas OOG: Oxidant off gas

Claims (2)

An electrolyte layer comprising a solid oxide;
An air electrode and a fuel electrode facing each other in a first direction across the electrolyte layer;
In the method for producing an electrochemical reaction cell, comprising: an intermediate layer disposed between the electrolyte layer and the air electrode, wherein at least one of the electrolyte layer and the fuel electrode includes partially stabilized Zr.
Preparing an electrolyte layer precursor, a fuel electrode precursor, and an intermediate layer precursor;
The electrolyte layer precursor, the fuel electrode precursor, and the intermediate layer precursor are subjected to a first heat treatment at a temperature equal to or higher than the phase transition temperature of the partially stabilized Zr, so that the electrolyte layer, the fuel electrode, Forming a laminate with the intermediate layer;
Performing a second heat treatment at a temperature lower than the phase transition temperature on the laminate for 10 hours or more;
Forming the electrochemical reaction cell by performing a third heat treatment at a temperature lower than the phase transition temperature on the laminated body and the air electrode precursor after the second heat treatment. A method for producing an electrochemical reaction cell. In the manufacturing method of the electrochemical reaction cell of Claim 1,
The method for producing an electrochemical reaction cell, wherein a time for performing the third heat treatment is shorter than a time for performing the second heat treatment.

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