JP2023081744A - Electrochemical reaction module and method for manufacturing electrochemical reaction module - Google Patents

Abstract

An object of the present invention is to suppress scattering of Mn contained in a specific member forming a gas flow path through which gas supplied to a fuel electrode flows into a fuel chamber. An electrochemical reaction module includes an electrochemical reaction device having 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, Further, a specific gas flow path is formed through which the gas supplied to the fuel electrode flows. At least part of the surface of the specific member, which is a member that defines the specific gas flow path and contains Mn, faces the specific gas flow path and is at least one selected from Mn and Si, Al, Ti and S An oxide film containing a specific element that is two elements and a specific compound that is a compound of two is formed. [Selection drawing] Fig. 8

Description

TECHNICAL FIELD The technology disclosed by this specification relates to an electrochemical reaction module and a method for manufacturing the electrochemical reaction module.

A solid oxide fuel cell (hereinafter referred to as "SOFC") is known as one type of fuel cell that generates power using an electrochemical reaction between hydrogen and oxygen. SOFCs are used, for example, in the form of fuel cell modules that include a fuel cell stack and other devices (see, for example, Patent Document 1). Other devices are, for example, combustors and reformers for generating gas (fuel gas) to be supplied to the fuel cell stack.

A fuel cell stack is a structure comprising multiple power generating units. Each power generation unit has a fuel cell single cell (hereinafter simply referred to as "single cell") including an electrolyte layer and an air electrode and a fuel electrode facing each other with the electrolyte layer interposed therebetween. Further, the fuel cell module is formed with a gas channel (hereinafter referred to as a "specific gas channel") through which gas supplied to the fuel electrode flows. A gas introduced into the fuel cell stack via the specific gas flow path and other devices described above is supplied to the anode.

JP 2019-091683 A

As a member that configures (defines) a specific gas flow path (for example, a fuel electrode-side gas supply flow path that connects a reformer and a fuel cell stack), which is a gas flow path through which gas supplied to the fuel electrode flows, A member containing Mn (manganese) may be used. In such a configuration in which the specific gas flow path contains Mn, the Mn contained in the specific gas flow path flows together with the gas in the gas flow path and eventually scatters into the fuel chamber, thereby creating a space facing the fuel electrode. The Mn vapor pressure in the fuel chamber increases, which can adversely affect the performance of the single cell (and thus the fuel cell stack), such as cracking of the electrolyte layer.

Note that such a problem is also common to an electrolytic module provided with an electrolytic cell stack, which is one form of an electrolytic cell (hereinafter referred to as "SOEC") that generates hydrogen using an electrolysis reaction of water. is. The electrolysis cell stack is a structure provided with an electrolysis block, which is a structure in which a plurality of electrolysis cell units each having a single electrolysis cell are arranged side by side in a predetermined direction. In this specification, a fuel cell single cell and an electrolysis single cell are collectively referred to as an electrochemical reaction single cell, a fuel cell power generation unit and an electrolysis cell unit are collectively referred to as an electrochemical reaction unit, and a fuel cell stack and an electrolysis cell are collectively referred to as an electrochemical reaction unit. The stack is collectively called an electrochemical reaction cell stack, and the fuel cell module and the electrolysis module are collectively called an electrochemical reaction module. Moreover, such problems are not limited to SOFCs and SOECs, but are common to other types of electrochemical reaction cell stacks and electrochemical reaction modules including such electrochemical reaction cell stacks.

This specification discloses a technology capable of solving the above-described problems.

The technology disclosed in this specification can be implemented, for example, in the following forms.

(1) The electrochemical reaction module disclosed in this specification has 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. A member that defines the specific gas flow path and contains Mn in an electrochemical reaction module that includes an electrochemical reaction device and in which a specific gas flow path through which a gas supplied to the fuel electrode flows is formed. A specific element that is a compound of Mn and at least one element selected from Si, Al, Ti and S, facing the specific gas flow path, on at least a part of the surface of the specific member An oxide film containing a compound is formed.

As described above, the present electrochemical reaction module has at least a portion of the surface of the specific member, which is a member that defines the specific gas flow path and contains Mn, facing the specific gas flow path, Mn and Si , Al, Ti, and S, and a specific compound, which is a compound of the specific element, is formed. Therefore, in this electrochemical reaction module, even though the specific member defining the specific gas flow path contains Mn, scattering of Mn contained in the specific member into the gas is suppressed. This is because Mn becomes a specific compound (a compound of Mn and a specific element) and is less likely to scatter in the gas. Therefore, according to the present electrochemical reaction module, it is possible to suppress an increase in the Mn vapor pressure in the fuel chamber as compared with the conventional technology, thereby improving the performance of the electrochemical reaction single cell.

(2) In the above electrochemical reaction module, the oxide film may have a structure in which MnO is not identified by X-ray diffraction. In this electrochemical reaction module, Mn contained in the specific member is less likely to scatter into the gas, compared to a configuration in which MnO is identified in the oxide film by X-ray diffraction. Therefore, according to this electrochemical reaction module, it is possible to more effectively suppress an increase in the Mn vapor pressure in the fuel chamber, thereby improving the performance of the electrochemical reaction single cell.

(3) In the above electrochemical reaction module, the specific member may contain Cr. In this electrochemical reaction module, Cr ₂ O ₃ is formed on the surface of the specific member. Therefore, a compound of Mn and a specific element formed on the surface of a specific member is used as a nucleus to form a compound of Mn and Cr ((Cr, Mn) ₃ O ₄ etc.) having a low vapor pressure of Mn. Scattering into the fuel chamber is further suppressed. Therefore, according to this electrochemical reaction module, it is possible to more effectively suppress an increase in the Mn vapor pressure in the fuel chamber, thereby improving the performance of the electrochemical reaction single cell.

(4) In the above electrochemical reaction module, the specific element is Si, and the specific compound is Mn ₂ SiO ₄ , or a part of at least one of Mn and Si contained in Mn ₂ SiO ₄ is another element. It is good also as a structure which is a compound substituted with. Since Si has particularly good reactivity with Mn, according to this electrochemical reaction module, compared with a configuration containing only specific elements other than Si (for example, Ti, Al, S), the fuel chamber can be more effectively can suppress an increase in the Mn vapor pressure in , thereby improving the performance of the electrochemical reaction single cell.

(5) In the above electrochemical reaction module, the electrochemical reaction single cell is a fuel cell single cell, and the electrochemical reaction module is a reformer having a space communicating with the specific gas flow path. , a reformer for reforming the gas supplied to the electrochemical reactor, wherein the Mn defining a portion between the reformer and the electrochemical reactor in the specific gas flow path is An oxide film containing the specific compound may be formed on at least part of the surface of the specific member containing the specific compound.

A reformer requires a high temperature (eg, 500 to 700° C.) for reforming. Therefore, the temperature of the gas passing through the high-temperature reformer and flowing through the portion between the reformer and the electrochemical reaction device in the specific gas flow path is high. Also, the higher the temperature of the gas, the easier it is for Mn to scatter from the specific surface of the specific member into the gas. Therefore, in the conventional configuration in which (all of) Mn contained in the specific surface of the specific member, which is the portion connecting the reformer and the electrochemical reaction device in the specific gas flow path, exists in a state where it is not a specific compound , Mn is particularly likely to scatter from the specific surface of the specific member into the gas.

In the present electrochemical reaction module, in such a configuration in which Mn is particularly likely to scatter in the gas, the specific compound is included on the specific surface of the specific member that defines the specific gas flow path and contains Mn as described above. The formation of the oxide film is particularly preferable because Mn contained in the specific member is suppressed from scattering into the gas.

(6) In the above method for manufacturing an electrochemical reaction module, a first material that is a material of a member that defines the specific gas flow path and contains Mn, and a second material that is a material containing the specific element are prepared. , a preparation step, and firing the first material and the second material in a state in which the first material and the second material are arranged in the same space in a firing furnace, thereby a firing step of forming the oxide film on a specific surface that is at least part of the surface defining the specific gas flow path, and subjecting a portion of the surface of the first material other than the specific surface to a heat treatment; , may be provided. According to this manufacturing method, compared to a manufacturing method in which the step of forming an oxide film on the specific surface of the first material and the step of heat-treating the portion other than the specific surface of the surface of the first material are performed separately. Therefore, the electrochemical reaction module can be manufactured efficiently.

(7) In the method for manufacturing an electrochemical reaction module, the firing step may be a step of performing firing in an air atmosphere. According to this manufacturing method, the electrochemical reaction module can be manufactured efficiently.

(8) In the above method for manufacturing an electrochemical reaction module, the firing step may be a step of performing firing in an inert atmosphere or in an atmosphere containing hydrogen. According to this manufacturing method, the electrochemical reaction module can be manufactured efficiently.

The technology disclosed in this specification can be implemented in various forms, for example, in the form of an electrochemical reaction module and its manufacturing method.

Explanatory drawing schematically showing the configuration of the fuel cell module 10 in the first embodiment. FIG. 2 is a perspective view showing the external configuration of the fuel cell stack 100 shown in FIG. 1; Explanatory drawing showing the XZ cross-sectional configuration of the fuel cell stack 100 at the position III-III in FIG. Explanatory diagram showing the XZ cross-sectional configuration of the fuel cell stack 100 at the position IV-IV in FIG. Explanatory drawing showing the YZ cross-sectional configuration of the fuel cell stack 100 at the position of VV in FIG. Explanatory diagram showing the 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. Explanatory diagram showing the 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. FIG. 2 is an explanatory diagram showing an enlarged XY cross-sectional configuration of a portion (X section in FIG. 1) of the fuel cell module 10; 4 is a flow chart showing a method for manufacturing the fuel cell module 10 according to the first embodiment; FIG. 8 is an explanatory diagram showing an enlarged XZ cross-sectional configuration of a portion of a fuel cell stack 100A provided in a fuel cell module 10A according to the second embodiment (portion corresponding to a portion of FIGS. 6 and 7).

A. First embodiment:
A-1. Configuration of fuel cell module 10:
FIG. 1 is an explanatory diagram schematically showing the configuration of a fuel cell module 10 according to the first embodiment. The fuel cell module 10 includes a fuel cell stack 100 and other devices (such as a reformer/heater 330, which will be described later). In the following, the configuration of the fuel cell stack 100 will be described first, and then the configuration of other devices that constitute the fuel cell module 10 will be described. The fuel cell module 10 is an example of an electrochemical reaction module in the claims, and the fuel cell stack 100 is an example of an electrochemical reaction device in the claims.

A-2. Configuration of fuel cell stack 100:
FIG. 2 is a perspective view showing the external configuration of the fuel cell stack 100 shown in FIG. FIG. 3 is an explanatory diagram showing the XZ cross-sectional configuration of the fuel cell stack 100 at the position III-III in FIG. FIG. 4 is an explanatory diagram showing the YZ cross-sectional configuration of the fuel cell stack 100 at the position IV-IV in FIG. FIG. 5 is an explanatory view showing the YZ cross-sectional configuration of the fuel cell stack 100 at the position of VV in FIG. Each figure shows mutually orthogonal XYZ axes for specifying the direction (the same applies to FIG. 6 and subsequent figures). In this specification, for the sake of convenience, the positive Z-axis direction is referred to as the upward direction, and the negative Z-axis direction is referred to as the downward direction. may be installed. Note that the installation orientation of the fuel cell stack 100 may be changed without changing the installation orientation of the fuel cell module 10 or the installation orientation of devices other than the fuel cell stack 100 (for example, the arrangement direction of the power generation units 102 may be the Y-axis direction). do).

As shown in FIGS. 2 to 5, the fuel cell stack 100 includes a plurality of (seven in this embodiment) fuel cells stacked in a predetermined arrangement direction (vertical direction (Z-axis direction) in this embodiment). It has a power generation unit (hereinafter simply referred to as “power generation unit”) 102 , a lower end separator 189 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 this embodiment). One of the pair of end plates 104 and 106 (hereinafter referred to as the "upper end plate 104") is located above the assembly composed of the power generation block 103 consisting of seven power generation units 102 and the lower end separator 189. The other of the pair of end plates 104 and 106 (hereinafter referred to as the “lower end plate 106”) is below the lower end separator 189 arranged below the power generation block 103. are placed. The pair of end plates 104 and 106 are arranged to sandwich the power generation block 103 and the lower end separator 189 from above and below. The arrangement direction (vertical direction) corresponds to the first direction in the scope of claims.

Holes penetrating vertically through each layer are formed near the four corners of the outer periphery around the Z-axis direction of each layer (upper end plate 104, each power generating unit 102, lower separator 189) that constitutes the fuel cell stack 100. Holes (screw holes) are formed in the upper surface of the lower end plate 106 in the vicinity of four corners of the outer periphery around the Z-axis direction. Corresponding holes formed in each layer communicate with each other in the vertical direction to form bolt holes 109 extending in the vertical direction. In the following description, the holes formed in each layer of the fuel cell stack 100 to constitute the bolt holes 109 may also be referred to as the bolt holes 109 .

A bolt 22 is inserted into each bolt hole 109 . The lower end of each bolt 22 is screwed into a screw hole formed in the lower end plate 106, and the upper end of each bolt 22 is fitted with a nut 24. As shown in FIG. The lower surface of nut 24 abuts the upper surface of end plate 104 via insulating sheet 26 . Each layer of the fuel cell stack 100 is integrally fastened by the bolts 22 and nuts 24 configured in this way. 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, or the like.

In addition, as shown in FIGS. 2 to 4, each layer (each power generation unit 102, lower end separator 189, lower end plate 106) constituting the fuel cell stack 100 has a peripheral portion around the Z-axis direction. Four vertically penetrating holes are formed, the corresponding holes formed in each layer are vertically communicated with each other, and the communicating hole extends vertically from the uppermost power generating unit 102 to the lower end plate 106. 108. In the following description, the holes formed in each layer of the fuel cell stack 100 to form the communication holes 108 may also be referred to as the communication holes 108 .

As shown in FIGS. 2 and 3, in the vicinity of one side (one of the two sides parallel to the Y-axis, the side on the positive side of the X-axis) that constitutes the outer circumference of the fuel cell stack 100 around the Z-axis direction. One communication hole 108 positioned is an air electrode, which is a gas flow path through which an oxidizing gas OG is introduced from the outside of the fuel cell stack 100 and which supplies the oxidizing gas OG to an air chamber 166 of each power generation unit 102, which will be described later. One communication hole 108 that functions as a side supply manifold 161 and is located near the side opposite to the side (the side on the negative side of the X-axis among the two sides parallel to the Y-axis) is connected to each power generation unit. It functions as an air electrode side discharge manifold 162 which is a gas flow path for discharging the oxidant offgas OOG, which is the gas discharged from the air chamber 166 of the fuel cell stack 102 , to the outside of the fuel cell stack 100 . Air, for example, is used as the oxidant gas OG.

2 and 4, among the sides forming the outer circumference of the fuel cell stack 100 around the Z-axis direction, the vicinity of the side closest to the communication hole 108 functioning as the air electrode side supply manifold 161 described above. Another communication hole 108 located in the fuel cell stack 100 is a gas flow path for introducing the fuel gas FG from the outside of the fuel cell stack 100 and supplying the fuel gas FG to a fuel chamber 176 of each power generation unit 102, which will be described later. Another communication hole 108 located near the side closest to the communication hole 108 functioning as the pole-side supply manifold 171 and functioning as the cathode-side exhaust manifold 162 described above is connected to the fuel chamber 176 of each power generation unit 102. It functions as the fuel electrode side discharge manifold 172 which is a gas flow path for discharging the fuel off-gas FOG, which is the discharged gas, to the outside of the fuel cell stack 100 . As the fuel gas FG, for example, hydrogen-rich gas obtained by reforming city gas is used.

As shown in FIGS. 3 and 4, the fuel cell stack 100 is provided with four gas passage members 27 . Each gas passage member 27 has a hollow tubular body portion 28 and a hollow tubular branch portion 29 branched from a side surface of the main body portion 28 . A hole in the branch portion 29 communicates with a hole in the main body portion 28 . A gas pipe (not shown) is connected to the branch portion 29 of each gas passage member 27 . 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 air electrode side supply manifold 161 communicates with the air electrode side supply manifold 161, and the air electrode side discharge manifold 162 is connected. The hole of the body portion 28 of the gas passage member 27 arranged at the position communicates with the air electrode side discharge manifold 162 . Further, as shown in FIG. 4, the hole of the main body portion 28 of the gas passage member 27 arranged at the position of the fuel electrode side supply manifold 171 communicates with the fuel electrode side supply manifold 171 and the fuel electrode side discharge manifold. A hole in the body portion 28 of the gas passage member 27 arranged at the position 172 communicates with the fuel electrode side discharge manifold 172 . An insulating sheet 26 is interposed between each gas passage member 27 and the surface of the lower end plate 106 .

(Configuration of end plates 104, 106)
As shown in FIGS. 3 to 5, the pair of end plates 104 and 106 are plate-like members having a substantially rectangular outer shape when viewed in the Z-axis direction, and are made of a conductive material such as stainless steel. Holes 32 and 34 penetrating in the Z-axis direction are formed near the center of the pair of end plates 104 and 106, respectively. As viewed in the Z-axis direction, the inner peripheral lines of the holes 32, 34 formed in the pair of end plates 104, 106 respectively include the unit cells 110, which will be described later. Therefore, the compressive force in the Z-axis direction generated by fastening with each bolt 22 and nut 24 acts mainly on the peripheral edge portion of each power generation unit 102 (portion on the outer peripheral side from each unit cell 110 described later). Further, in this embodiment, the upper end plate 104 functions as a positive output terminal of the fuel cell stack 100 , and the lower end plate 106 functions as a negative output terminal of the fuel cell stack 100 .

(Structure of Lower End Separator 189)
As shown in FIGS. 3 to 5, the bottom separator 189 is a plate-like member having a substantially rectangular outer shape when viewed in the Z-axis direction, and is made of metal, for example. The peripheral edge portion of the lower end separator 189 is sandwiched between the power generation block 103 and the lower end plate 106 and is joined to the lower end plate 106 by, for example, welding. It is connected to the.

(Configuration of power generation unit 102)
6 is an explanatory diagram showing the 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. 3, and FIG. FIG. 3 is an explanatory diagram showing an XZ cross-sectional configuration of two power generation units 102;

As shown in FIGS. 6 and 7, the power generation unit 102 includes a fuel cell single cell (hereinafter referred to as "single cell") 110, a single cell separator 120, and the top and bottom layers of the power generation unit 102. A pair of interconnectors 190 , an interconnector separator 191 , an air electrode-side frame 130 , a fuel electrode-side frame 140 , and a fuel electrode-side collector 144 are provided. Communicating holes 108 functioning as manifolds 161, 162, 171, 172 are formed in the periphery of the unit cell separator 120, the air electrode side frame 130, the fuel electrode side frame 140, and the interconnector separator 191 around the Z-axis direction. and holes forming each bolt hole 109 are formed.

The unit cell 110 includes an electrolyte layer 112, an air electrode 114 and a fuel electrode 116 facing each other in the Z-axis direction with the electrolyte layer 112 interposed therebetween, and a reaction prevention layer 118 disposed between the electrolyte layer 112 and the air electrode 114. and a single fuel cell. The single cell 110 of this embodiment is a fuel electrode supporting type single cell in which the fuel electrode 116 supports the other layers (electrolyte layer 112, air electrode 114, reaction prevention layer 118) that constitute the single cell 110. . The single cell 110 is an example of an electrochemical reaction single cell in the claims.

The electrolyte layer 112 is a substantially rectangular plate-shaped member when viewed in the Z-axis direction, and is configured to contain a solid oxide (for example, YSZ (yttria-stabilized zirconia)). That is, the single cell 110 of this embodiment is a solid oxide fuel cell (SOFC) using a solid oxide as an electrolyte. The air electrode 114 is a substantially rectangular plate-shaped member smaller than the electrolyte layer 112 when viewed in the Z-axis direction, and is configured to contain, for example, a perovskite oxide (for example, LSCF (lanthanum strontium cobalt iron oxide)). . The fuel electrode 116 is a substantially rectangular plate-shaped member having substantially the same size as the electrolyte layer 112 when viewed in the Z-axis direction, and is formed of, for example, Ni (nickel), a cermet made of Ni and ceramic particles, a Ni-based alloy, or the like. ing. The reaction prevention layer 118 is a substantially rectangular plate-shaped member having substantially the same size as the air electrode 114 when viewed in the Z-axis direction, and is configured to contain, for example, GDC (gadolinium-doped ceria) and YSZ. The reaction prevention layer 118 prevents an element (eg, Sr) diffused from the air electrode 114 from reacting with an element (eg, Zr) contained in the electrolyte layer 112 to produce a high-resistance substance (eg, SrZrO3). It has a suppressing function.

The single-cell separator 120 is a frame-shaped member having a substantially rectangular through-hole 121 penetrating vertically in the vicinity of the center thereof, and is made of metal, for example. A portion of the single-cell separator 120 surrounding the through-hole 121 (hereinafter referred to as a “through-hole surrounding portion”) faces the upper surface of the peripheral portion of the single-cell 110 (electrolyte layer 112 ). The unit cell separator 120 is joined (connected) to the unit cell 110 (electrolyte layer 112) by a joining portion 124 formed of a brazing material (for example, Ag brazing) arranged at the opposing portion. An air chamber 166 facing the air electrode 114 and a fuel chamber 176 facing the fuel electrode 116 are partitioned by the single cell separator 120, and gas flows from one electrode side to the other electrode side in the peripheral portion of the single cell 110. leak (cross leak) is suppressed.

A glass seal portion 125 containing glass is arranged near the through hole 121 in the single cell separator 120 . The glass seal portion 125 is positioned on the air chamber 166 side with respect to the joint portion 124, and the surface of the unit cell separator 120 around the through hole and the surface of the unit cell 110 (the electrolyte layer 112 in this embodiment) is formed to contact both the The glass seal portion 125 effectively suppresses gas leak (cross leak) from one electrode side to the other electrode side in the peripheral portion of the unit cell 110 .

The interconnector 190 is a conductive member having a substantially rectangular flat plate-shaped flat plate portion 150 and a plurality of substantially columnar air electrode side current collectors 134 projecting from the flat plate portion 150 toward the air electrode 114 side, It is made of a metal containing Mn and Cr (for example, ferritic stainless steel). In this embodiment, the surface of the interconnector 190 (the surface facing the air chamber 166) is formed with a conductive coating layer 194 made of, for example, spinel oxide. Below, the interconnector 190 covered with the covering layer 194 is simply referred to as the interconnector 190 . In each power generation unit 102, the upper interconnector 190 is arranged above the single cell 110 with the air chamber 166 interposed therebetween (on the opposite side of the air electrode 114 from the electrolyte layer 112 in the Z-axis direction). . The upper interconnector 190 (each air electrode side current collector 134) is joined to the air electrode 114 of the unit cell 110 via a conductive joint material 196 made of, for example, spinel oxide. is electrically connected to the air electrode 114 of the single cell 110 by . In addition, in each power generation unit 102, the lower interconnector 190 is arranged below the unit cell 110 with the fuel chamber 176 interposed therebetween. It is electrically connected to the anode 116 of the cell 110 . The interconnector 190 ensures electrical continuity between the power generation units 102 and suppresses mixing of reaction gases between the power generation units 102 . In addition, in this embodiment, when two power generation units 102 are arranged adjacently, one interconnector 190 is shared by the two adjacent power generation units 102 . That is, the upper interconnector 190 in one power generation unit 102 is the same member as the lower interconnector 190 in another power generation unit 102 adjacent to the upper side of the power generation unit 102 . In addition, since the fuel cell stack 100 includes the lower end separator 189, the lowermost power generation unit 102 in the fuel cell stack 100 does not include the lower interconnector 190 (see FIGS. 3 to 5). .

The interconnector separator 191 is a frame-like member in which a substantially rectangular through-hole 181 penetrating in the vertical direction is formed near the center, and is made of metal, for example. A portion of the interconnector separator 191 surrounding the through-hole 181 (hereinafter referred to as “through-hole surrounding portion”) is joined to the upper surface of the peripheral portion of the interconnector 190 by welding, for example. Of the pair of interconnector separators 191 included in a certain power generation unit 102, the upper interconnector separator 191 is connected to the air chamber 166 of the power generation unit 102 and the other power generation unit adjacent to the power generation unit 102 on the upper side. It separates the fuel chamber 176 of the unit 102 . Further, of the pair of interconnector separators 191 included in a given power generation unit 102, the lower interconnector separator 191 is adjacent to the fuel chamber 176 of the power generation unit 102 and the power generation unit 102 on the lower side. It separates the air chambers 166 of other power generating units 102 to which it fits. In this manner, the interconnector separator 191 suppresses gas leakage between the power generation units 102 at the periphery of the power generation units 102 . The interconnector separator 191 joined to the upper interconnector 190 of the power generating unit 102 located at the uppermost position in the fuel cell stack 100 is electrically connected to the upper end plate 104 .

The air electrode side frame 130 is a frame-shaped member having a substantially rectangular hole 131 penetrating vertically in the vicinity of the center thereof, and is made of an insulator such as mica, for example. A hole 131 in the cathode-side frame 130 constitutes an air chamber 166 facing the cathode 114 . The air electrode side frame 130 is in contact with the upper surface of the periphery of the single cell separator 120 and the lower surface of the periphery of the upper interconnector separator 191, and the gas sealing property between them is maintained. (that is, the gas sealing property of the air chamber 166). In addition, the air electrode side frame 130 electrically insulates between the pair of interconnector separators 191 included in the power generation unit 102 (that is, between the pair of interconnectors 190). The air electrode side frame 130 includes an air electrode side supply communication passage 132 that communicates the air electrode side supply manifold 161 and the air chamber 166, and an air electrode side discharge passage that communicates the air chamber 166 and the air electrode side discharge manifold 162. A communication channel 133 is formed.

The fuel electrode-side frame 140 is a frame-shaped member having a substantially rectangular hole 141 penetrating vertically in the vicinity of the center thereof, and is made of metal, for example. A hole 141 in the anode-side frame 140 constitutes a fuel chamber 176 facing the anode 116 . The fuel electrode-side frame 140 is in contact with the lower surface of the periphery of the single cell separator 120 and the upper surface of the periphery of the lower interconnector separator 191 . The fuel electrode side frame 140 has a fuel electrode side supply communication passage 142 that communicates the fuel electrode side supply manifold 171 and the fuel chamber 176, and a fuel electrode side discharge passage that communicates the fuel chamber 176 and the fuel electrode side discharge manifold 172. A communication channel 143 is formed.

The fuel electrode side collector 144 is arranged in the fuel chamber 176 . The fuel electrode-side 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 is used. , stainless steel or the like. The electrode facing portion 145 is in contact with the lower surface of the fuel electrode 116 , and the interconnector facing portion 146 is in contact with the upper surface of the interconnector 190 . However, as described above, since the power generation unit 102 located on the lowest side in the fuel cell stack 100 does not have the lower interconnector 190, the fuel electrode side current collector 144 in the power generation unit 102 faces the interconnector. The portion 146 is in contact with the bottom separator 189 . Since the fuel electrode side current collector 144 has such a configuration, it electrically connects the fuel electrode 116 and the interconnector 190 (or the lower end separator 189). A spacer 149 made of mica, for example, is arranged between the electrode-facing portion 145 and the interconnector-facing portion 146 of the fuel electrode-side collector portion 144 . Therefore, the fuel electrode side current collector 144 follows the deformation of the power generation unit 102 due to the temperature cycle and reaction gas pressure fluctuation, and the fuel electrode 116 and the interconnector 190 (or the lower end separator 189) through the fuel electrode side current collector 144. ) is well maintained.

A-3. Configuration of devices other than fuel cell stack 100 in fuel cell module 10:
Next, configurations of devices other than the fuel cell stack 100 in the fuel cell module 10 will be described. As shown in FIG. 1, the fuel cell module 10 includes an auxiliary device 300 including an evaporator 310 and a reformer/heater 330, and various flow paths connecting each device. Each device (fuel cell stack 100 , auxiliary device 300 ) is housed in a heat insulating space 351 surrounded by a heat insulating material 350 . In FIG. 1, the heat insulating material 350 is assumed to have a simple rectangular shape that covers the entire device for the sake of convenience. ing. In FIG. 1, the flow of the gas on the fuel electrode side (including raw fuel gas RFG, fuel gas FG, and fuel offgas FOG) is indicated by a dashed line, and the gas on the air electrode side (oxidant gas OG and oxidant offgas OOG) is indicated by a dashed line. ) are indicated by solid lines, the flow of exhaust gas EG is indicated by dashed lines, and the flow of water is indicated by chain double-dashed lines.

The evaporator 310 is a box-shaped member with a space formed therein, and is made of metal, for example. The evaporator 310 is a device for evaporating the water WA to generate steam. A pure water introduction passage 251 for introducing water WA is connected to the evaporator 310 . The pure water introduction channel 251 is mainly composed of a pipe, and on the pure water introduction channel 251, there are an ion exchange resin (not shown), a purified water tank float (not shown), and a flow rate control mechanism. (not shown) are provided. Water WA supplied from a water supply source (not shown) to the pure water introduction channel 251 is subjected to removal of calcium ions and the like in the ion exchange resin, purified and stored in the purified water tank/float, and controlled by the flow rate control mechanism. It is introduced into the evaporator 310 as pure water at the set flow rate.

A raw fuel gas introduction passage 261 for introducing the raw fuel gas RFG is connected to the evaporator 310 . The raw fuel gas introduction channel 261 is mainly composed of a pipe, and a flow rate control mechanism (not shown) and a hydrogen addition desulfurizer (not shown) are provided on the raw fuel gas introduction channel 261. It is The raw fuel gas RFG supplied from the gas source to the raw fuel gas introduction passage 261 is introduced into the evaporator 310 at a flow rate controlled by the flow rate control mechanism in a state where the sulfur component is removed in the hydrodesulfurizer. .

Further, the evaporator 310 includes an exhaust gas relay passage 226 for sending the exhaust gas EG from a housing 335 (described later) of the reformer/heater 330 to the evaporator 310, A mixed gas passage 228 for sending mixed gas to a qualityr 331 (described later) and an exhaust gas discharge passage (not shown) for discharging exhaust gas EG from the evaporator 310 are connected. These flow paths are mainly composed of pipes.

The reformer/heater 330 includes a reformer 331 , a combustor 333 and a housing 335 . The housing 335 is a closed container made of metal, for example, and accommodates the reformer 331 and the combustor 333 . The housing 335 has a double wall structure having an inner wall 336 and an outer wall 337, and heat transfer fins 339 are arranged in an air flow path 338 formed between the inner wall 336 and the outer wall 337. there is 1, illustration of a portion of the heat transfer fins 339 is omitted. An air introduction channel 271 for introducing an oxidant gas OG (air) is connected to the housing 335 . The air introduction channel 271 is mainly configured by piping, and a flow rate control mechanism (not shown) is provided on the air introduction channel 271 . The oxidant gas OG supplied to the air introduction channel 271 is introduced into the air channel 338 of the housing 335 at a flow rate controlled by the flow control mechanism. Further, the housing 335 is connected to an air electrode side gas supply passage 61 for sending out the oxidant gas OG toward an air electrode side supply manifold 161 (described later) of the fuel cell stack 100 . The cathode-side gas supply channel 61 is mainly configured by piping.

The reformer 331 is a box-shaped member having a space inside, and is made of metal, for example. The reformer 331 is a device for reforming (steam reforming) the raw fuel gas RFG to generate the fuel gas FG. A catalyst that accelerates the reforming reaction is arranged in the reformer 331 . As described above, the reformer 331 is connected to the mixed gas flow path 228 for sending the mixed gas from the evaporator 310 to the reformer 331 . Further, the reformer 331 is connected to a fuel electrode side gas supply passage 71 for delivering the fuel gas FG toward a fuel electrode side supply manifold 171 (described later) of the fuel cell stack 100 . The fuel electrode side gas supply channel 71 is mainly configured by a pipe.

The combustor 333 is a box-shaped member with a space formed therein, and is made of metal, for example. The combustor 333 is a device for burning the oxidant offgas OOG and the fuel offgas FOG. A catalyst may be placed in the combustor 333 to promote combustion of the oxidant off-gas OOG and the fuel off-gas FOG. The combustor 333 includes an air electrode side gas discharge passage 240 through which the oxidant offgas OOG is sent from the air electrode side discharge manifold 162 of the fuel cell stack 100 and a fuel offgas FOG from the fuel electrode side discharge manifold 172 of the fuel cell stack 100 . is connected to the fuel electrode side gas discharge channel 230 through which the gas is delivered. These flow paths are mainly composed of pipes.

A-4. Operation of fuel cell module 10:
Next, operation of the fuel cell module 10 will be described. As shown in FIG. 1 , the oxidant gas OG flows through the air introduction channel 271 and is introduced into the air channel 338 formed in the housing 335 of the reformer/heater 330 . The oxidant gas OG introduced into the air flow path 338 flows through the air flow path 338 while being heated by combustion heat (exhaust gas EG) generated by the combustor 333, and passes through the air electrode side gas supply flow path 61. and supplied to the air electrode side supply manifold 161 of the fuel cell stack 100 . As shown in FIGS. 3 and 5, the oxidant gas OG supplied to the air electrode side supply manifold 161 is supplied from the air electrode side supply manifold 161 through the air electrode side supply communication channel 132 of each power generation unit 102. Air chamber 166 is supplied. Further, as shown in FIG. 1, the raw fuel gas RFG is supplied to the evaporator 310 through the raw fuel gas introduction passage 261, and the water WA is supplied to the evaporator 310 through the pure water introduction passage 251. Then, in the evaporator 310, the heat of the exhaust gas EG introduced through the exhaust gas relay passage 226 is used to evaporate the water WA, thereby generating steam, which is combined with the raw fuel gas RFG. mixed. The raw fuel gas RFG mixed with steam is introduced from the evaporator 310 into the reformer 331 through the mixed gas flow path 228 and steam-reformed in the reformer 331, resulting in a hydrogen-rich fuel gas FG. is generated. The generated fuel gas FG is supplied to the fuel electrode side supply manifold 171 of the fuel cell stack 100 through the fuel electrode side gas supply channel 71 . As shown in FIGS. 4 and 6, the fuel gas FG supplied to the fuel electrode side supply manifold 171 flows from the fuel electrode side supply manifold 171 through the fuel electrode side supply communication channel 142 of each power generation unit 102. chamber 176 is supplied.

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, the oxygen contained in the oxidant gas OG and the fuel gas in the single cell 110 of each power generation unit 102 Electricity is generated by an electrochemical reaction with hydrogen contained in the FG. 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 190 through the air electrode side current collector 134, and the fuel electrode 116 is electrically connected through the fuel electrode side current collector 144. It is electrically connected to the other interconnector 190 . Also, the plurality of power generation units 102 included in the fuel cell stack 100 are electrically connected in series. Therefore, the 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 . Note that the SOFC generates power at a relatively high temperature (for example, 700° C. to 1000° C.).

As shown in FIGS. 1, 3 and 6, the oxidant offgas OOG discharged from the air chamber 166 of each power generation unit 102 to the air electrode side discharge manifold 162 through the air electrode side discharge communication passage 133 is It is introduced into the combustor 333 via the pole-side gas discharge channel 240 . Further, as shown in FIGS. 1, 4 and 7, the fuel off-gas FOG discharged from the fuel chamber 176 of each power generation unit 102 to the fuel electrode side discharge manifold 172 through the fuel electrode side discharge communication passage 143 is It is introduced into the combustor 333 via the fuel electrode side gas discharge channel 230 . The oxidant offgas OOG and the fuel offgas FOG introduced into the combustor 333 are mixed and burned in the combustor 333 and then discharged as exhaust gas EG to the evaporator 310 via the exhaust gas relay passage 226 . The heat generated in the combustor 333 accelerates the reforming reaction in the reformer 331 and heats the fuel cell stack 100 .

A-5. Detailed configuration of fuel electrode side gas supply channel 71 and its surroundings:
As described above, the fuel electrode side gas supply channel 71 is a channel for sending out the fuel gas FG from the reformer 331 toward the fuel electrode side supply manifold 171 of the fuel cell stack 100 (see FIG. 1). ), and as shown in FIG. Hereinafter, a member that configures (defines) the fuel electrode-side gas supply channel 71 is referred to as a specific piping member 71P. The specific piping member 71P is an example of a specific member in the claims.

FIG. 8 is an explanatory view showing an enlarged XY cross-sectional configuration of a portion (X section in FIG. 1) of the fuel cell module 10. As shown in FIG. FIG. 8 shows the XY cross-sectional configuration of the specific piping member 71P that configures (defines) the fuel electrode-side gas supply channel 71. As shown in FIG. In addition, in FIG. 8, only a part of the specific piping member 71P is shown, and illustration of other parts is omitted.

The raw fuel gas introduction channel 261 formed in the fuel cell module 10, the mixed gas channel 228, the fuel electrode side gas supply channel 71, and the channel through which the fuel gas FG passes in the fuel cell stack 100 ( A series of gas flow paths (hereinafter referred to as "specific gas ) 400 can be said to be a gas flow path through which the gas supplied to the fuel electrode 116 flows. At this time, the fuel electrode-side gas supply channel 71 can be said to be a part of the specific gas channel 400 , and the portion of the specific gas channel 400 that connects the reformer 331 and the fuel cell stack 100 . It can be said that

As shown in FIG. 8, the specific piping member 71P is a tubular member having a gas flow path formed therein. The specific piping member 71P is made of a member (for example, metal) containing Mn (manganese) and Cr (chromium).

At least a portion (hereinafter referred to as “specific surface”) 71S of the surface of the specific piping member 71P (the surface defining the flow path through which the gas flowing to the fuel electrode 116 passes) contains a compound of Mn and Si (silicon). An oxide film OC1 is formed. Si corresponds to at least one element (hereinafter referred to as "specific element") selected from Si, Al (aluminum), Ti (titanium) and S (sulfur). Also, the compound of Mn and Si is Mn ₂ SiO ₄ (manganese silicate) or a compound in which at least one of Mn and Si contained in Mn ₂ SiO ₄ is partly replaced with another element. Incidentally, Si is an example of a specific element in the scope of claims, and a compound of Mn and Si is an example of a specific compound in the scope of claims.

The oxide film OC1 of the present embodiment is a compound in which at least one of Mn and Si contained in M, n ₂ SiO ₄ , or Mn ₂ SiO ₄ is partially substituted with another element by an X-ray diffraction method. are identified, while MnO is not. The measurement conditions for this X-ray diffraction method are as follows. That is, the tube voltage is 40 kV, the tube current is 20 mA, and the wavelength is CuKα (1.541862 Å). Moreover, the above-mentioned "MnO is not identified" means that two or more peaks attributed to MnO are not observed in the measurement range of 10° to 80° (the same shall apply hereinafter).

The content of the specific element (Si) in the oxide film OC1 of this embodiment is 10% by mass or more (for example, 14% by mass in the case of Mn ₂ SiO ₄ ). The content of the specific element (Si) in the oxide film OC1 is measured by performing ICP emission spectrometry on a sample obtained by dissolving the oxide film OC1 (the specific piping member 71P having the oxide film OC1 formed thereon) using nitric acid or the like. be able to.

A-6. Manufacturing method of fuel cell module 10:
FIG. 9 is a flow chart showing a method for manufacturing the fuel cell module 10 according to the first embodiment. A method of manufacturing the fuel cell module 10 is, for example, as follows.

First, a first material M1, which is the material of the specific piping member 71P, and a second material M2, which is a material containing a specific element (Si), are prepared (preparation step S11). The first material M1 is a member (for example, metal) containing Mn and Cr. The second material M2 is mica, for example. Hereinafter, of the surface of the first material M1, the portion forming the oxide film OC1 containing the compound of Mn and Si (silicon) is referred to as "specific surface 71S".

Next, the first material M1 and the second material M2 are fired while the first material M1 and the second material M2 are placed in the same space in the firing furnace. As a result, an oxide film OC1 is formed on the specific surface 71S of the first material M1, and heat treatment is performed on the surface of the first material M1 other than the specific surface 71S. Specifically, in the same space in the firing furnace, the first material M1 and the second material M2 are arranged such that the second material M2 faces the specific surface 71S of the first material M1. As for the firing method, for example, in the case of a member that can allow dimensional change due to the formation of an oxide film, the firing is performed in an air atmosphere (the firing temperature is, for example, 1000° C.), and the dimensional change due to the formation of an oxide film is not allowed. In the case of members (for example, joints and bolts with screws), firing may be performed in an inert atmosphere or in an atmosphere containing hydrogen (at a firing temperature of 900° C., for example). Instead of such a treatment, the second material M2 (mica) is mixed with water, and the steam bubbling with hydrogen gas is placed inside the first material M1 maintained at a predetermined temperature (for example, about 850° C.) for a predetermined time ( For example, about 10 hours), Si may adhere to the specific surface 71S of the first material M1. By performing these treatments, an oxide film OC1 containing Mn ₂ SiO ₄ or the like, which is a compound of Mn and Si, is formed on the specific surface 71S of the first material M1.

Next, the remaining steps such as assembling the specific piping member 71P and assembling other devices, flow paths, etc. are performed (S13), thereby completing the manufacture of the fuel cell module 10 having the configuration described above.

A-7. Effect of the first embodiment:
As described above, the fuel cell module 10 of the present embodiment includes a single cell 110 including an electrolyte layer 112 containing a solid oxide, and an air electrode 114 and a fuel electrode 116 facing each other with the electrolyte layer 112 interposed therebetween. A fuel cell stack 100 is provided. The fuel cell module 10 is formed with a specific gas flow path 400 through which the gas supplied to the fuel electrode 116 flows. At least part of the surface (hereinafter referred to as “specific surface”) 71S of the specific piping member 71P, which is a member that defines the specific gas flow path 400 and contains Mn, faces the specific gas flow path 400 and contains Mn. and a specific element (Si), an oxide film OC1 containing a specific compound is formed.

As described above, in the fuel cell module 10 of the present embodiment, the specific surface 71S of the specific piping member 71P, which is a member that defines the specific gas flow path 400 and contains Mn, faces the specific gas flow path 400, and , Mn and a specific element (Si). Therefore, in the fuel cell module 10 of the present embodiment, although the specific piping member 71P defining the specific gas flow path 400 contains Mn, Mn contained in the specific piping member 71P may scatter in the gas. Suppressed. This is because Mn becomes a specific compound (a compound of Mn and a specific element (Si)) and is less likely to scatter in the gas. Therefore, according to the fuel cell module 10 of the present embodiment, it is possible to suppress an increase in the Mn vapor pressure in the fuel chamber 176 compared to the conventional technology, thereby improving the performance of the single cell 110. can.

In the fuel cell module 10 of this embodiment, MnO is not identified in the oxide film OC1 by the X-ray diffraction method. Therefore, in the fuel cell module 10 of the present embodiment, Mn contained in the specific piping member 71P is less likely to scatter in the gas, compared to the structure in which MnO is identified in the oxide film OC1 by the X-ray diffraction method. unlikely to occur. Therefore, according to the fuel cell module 10 of this embodiment, it is possible to more effectively suppress the increase in the Mn vapor pressure in the fuel chamber 176, thereby improving the performance of the single cell 110. FIG.

In the fuel cell module 10 of this embodiment, the specific piping member 71P, which is a member containing Mn, contains Cr. Therefore, in the fuel cell module 10 of this embodiment, Cr ₂ O ₃ is formed on the surface of the specific piping member 71P. Therefore, a compound of Mn and a specific element (Si) formed on the surface of the specific piping member 71P is used as a nucleus to form a compound of Mn and Cr ((Cr, Mn) ₃ O ₄ etc.) having a low Mn vapor pressure, This further suppresses scattering of Mn into the fuel chamber 176 . Therefore, according to the fuel cell module 10 of this embodiment, it is possible to more effectively suppress the increase in the Mn vapor pressure in the fuel chamber 176, thereby improving the performance of the single cell 110. FIG.

In the fuel cell module 10 of the present embodiment, the specific element (at least one element selected from Si, Al, Ti and S) is Si, and the specific compound (compound of Mn and Si) is Mn ₂ SiO. ₄ or Mn ₂ SiO ₄ is a compound in which at least one of Mn and Si contained in Mn 2 SiO 4 is partially substituted with another element. Since Si has particularly good reactivity with Mn, according to the fuel cell module 10 of the present embodiment, compared with a configuration containing only specific elements other than Si (for example, Ti, Al, S), , the increase in the Mn vapor pressure in the fuel chamber 176 can be suppressed, thereby improving the performance of the single cell 110 .

In the fuel cell module 10 of this embodiment, the single cell 110 is a single fuel cell. The fuel cell module 10 includes a reformer 331 having a space communicating with the specific gas flow path 400 and reforming the gas supplied to the fuel cell stack 100 . A specific compound (a compound of Mn and a specific element (Si)) is contained in a portion (anode-side gas supply channel 71) of the specific gas channel 400 that connects the reformer 331 and the fuel cell stack 100. An oxide film OC1 is formed.

The reformer 331 requires a high temperature (for example, 500 to 700° C.) for reforming. Therefore, the temperature of the gas that passes through the reformer 331, which has a high temperature, and flows through the portion of the specific gas flow path 400 between the reformer 331 and the fuel cell stack 100 becomes high. Also, the higher the temperature of the gas, the easier it is for Mn to scatter from the specific surface 71S of the specific piping member 71P into the gas. Therefore, (all of) Mn contained in the specific surface 71S of the specific piping member 71P, which is the portion connecting the reformer 331 and the fuel cell stack 100 in the specific gas flow path 400, exists in a state where it is not a specific compound. In the conventional configuration, Mn is particularly likely to scatter from the specific surface 71S into the gas.

In the fuel cell module 10 of the present embodiment, in such a configuration in which Mn is particularly likely to scatter in the gas, as described above, the specific piping member 71P, which is a member that defines the specific gas flow path 400 and contains Mn, is specified. Formation of the oxide film OC1 containing the specific compound on the surface 71S is particularly preferable because Mn contained in the specific piping member 71P is prevented from scattering into the gas.

The manufacturing method of the fuel cell module 10 of this embodiment includes the preparation step S11 and the firing step S12 described above. In the preparation step S11, the first material M1, which is the material of the specific piping member 71P, which defines the specific gas flow path 400 and contains Mn, and the second material M2, which is the material containing the specific element (Si), are prepared. This is the preparation process. In the firing step S12, the first material M1 and the second material M2 are placed in the same space in the firing furnace, and the first material M1 and the second material M2 are fired to specify the first material M1. In this step, an oxide film OC1 is formed on the surface 71S, and a heat treatment is applied to portions of the surface of the first material M1 other than the specific surface 71S. According to this manufacturing method, the step of forming the oxide film OC1 on the specific surface 71S of the first material M1 and the step of heat-treating the portion of the surface of the first material M1 other than the specific surface 71S are performed separately. The fuel cell module 10 can be manufactured more efficiently than the manufacturing method.

In the method for manufacturing the fuel cell module 10 of the present embodiment, the firing step S12 may be a step of performing firing in an air atmosphere. According to this manufacturing method, the fuel cell module 10 can be manufactured efficiently.

In the method of manufacturing the fuel cell module 10 of the present embodiment, the firing step S12 may be a step of performing firing in an inert atmosphere or in an atmosphere containing hydrogen. According to this manufacturing method, the fuel cell module 10 can be manufactured efficiently.

B. Second embodiment:
FIG. 10 is an explanatory diagram showing an enlarged XZ cross-sectional configuration of a portion of the fuel cell stack 100A provided in the fuel cell module 10A in the second embodiment (portion corresponding to a portion of FIGS. 6 and 7).

The configuration of the fuel cell module 10A of the second embodiment is basically the same as the configuration of the fuel cell module 10 of the first embodiment, except that the configuration of the interconnector 190A of the fuel cell stack 100A is different. In the following, among the configurations of the fuel cell module 10A of the second embodiment, the same configurations as those of the fuel cell module 10 of the first embodiment described above are denoted by the same reference numerals, and descriptions thereof will be omitted as appropriate.

As shown in FIG. 10, the surface of the interconnector 190A (more specifically, the portion corresponding to the flat plate portion 150) of the fuel cell stack 100A included in the fuel cell module 10A in the second embodiment (the gas flowing to the fuel electrode 116 is An oxide film OC2 containing a specific compound, which is a compound of Mn and a specific element (Si), is formed on at least a portion (hereinafter referred to as a “specific surface”) 190S of the surface defining the fuel chamber 176, which is a passage through which the fuel chamber 176 passes. formed. The interconnector 190A, which is a member that defines the fuel chamber 176, is a member that configures (defines) a part of the specific gas flow path 400A, which is a gas flow path through which the gas supplied to the fuel electrode 116 flows. It corresponds to a specific member in the scope of claims.

According to the fuel cell module 10A of the present embodiment, as described above, the oxide film OC2 containing the specific compound (the compound of Mn and the specific element (Si)) is formed on the specific surface 190S of the interconnector 190A. , the same effect as that of the oxide film OC1 in the first embodiment can be obtained. That is, according to the fuel cell module 10A of the present embodiment, it is possible to suppress an increase in the Mn vapor pressure in the fuel chamber 176 compared to the conventional technology, thereby improving the performance of the single cell 110. can.

MnO is not identified in the oxide film OC2 of this embodiment by the X-ray diffraction method. Moreover, the interconnector 190A of the present embodiment is formed of a member containing Mn and Cr (for example, ferritic stainless steel). Moreover, the content of the specific element (Si) in the oxide film OC2 of the present embodiment is 10% by mass or more (for example, 14% by mass in the case of Mn ₂ SiO ₄ ). The effects of these configurations are basically obtained in the same manner as in the first embodiment.

In this embodiment, an oxide film OC1 containing a compound of Mn and a specific element (Si) may be formed on the specific surface 71S of the specific piping member 71P as in the first embodiment. OC1 may not be formed.

The manufacturing method of the fuel cell module 10A of this embodiment is basically the same, but an oxide film OC2 is formed on the specific surface 190S of the first material M1 (material of the interconnector 190A in this embodiment), As the heat treatment performed on the surface of the first material M1 other than the specific surface 190S, for example, a paste material for forming the coating layer 194 may be baked on the surface of the interconnector 190A.

C. Variant:
The technology disclosed in this specification is not limited to the above-described embodiments, and can be modified in various forms without departing from the scope of the invention. For example, the following modifications are possible.

The configuration of the fuel cell module 10 and the configuration of each part constituting the fuel cell module 10 in the above-described embodiment are merely examples, and various modifications are possible. The configurations of the fuel cell stacks 100 and 100A in the above-described embodiments and the configurations of the parts that constitute the fuel cell stacks 100 and 100A are only examples, and various modifications are possible.

In the above embodiment, Mn and a specific element (Si is at least one selected from Si, Al, Ti and S) are added to the surface of the specific piping member 71P (specific surface 71S) and the surface of the interconnector 190A (specific surface 190S). The oxide films OC1 and OC2 containing specific compounds which are compounds with one element) are formed, but define the specific gas flow paths 400 and 400A through which the gas supplied to the fuel electrode 116 flows, and also contain Mn. A structure in which an oxide film containing a specific compound is formed on the surface of the member may also be used. In this configuration, the other member corresponds to a specific member in the claims, and the surface of the other member on which the oxide film is formed (the surface that defines the flow path through which the gas flowing to the fuel electrode 116 passes) corresponds to a specific surface.

In the above embodiment, the specific element (Si is at least one element selected from Si, Al, Ti and S) is Si, and Si is particularly preferred because it is easily volatilized when it comes into contact with water vapor, but instead of or in addition to Si , an element other than Si (eg, Al, Ti, S) may be employed as the specific element.

Although MnO is not identified in the oxide films OC1 and OC2 by the X-ray diffraction method in the above embodiment, MnO may be identified by the X-ray diffraction method.

In the second embodiment, the oxide film OC2 is formed on the interconnectors 190A of all the power generation units 102 included in the fuel cell stack 100A. It is not necessary to form the coating OC2, and it is sufficient that at least one power generation unit 102 is formed with the oxide coating OC2.

The members that define the specific gas flow paths 400 and 400A through which the gas supplied to the fuel electrode 116 flows and that contain Mn (the specific piping member 71P and the interconnector 190A) may not contain Cr.

Moreover, although the interconnector 190 includes the conductive coating layer 194 in the above embodiment, the interconnector 190 may not include the coating layer 194 . Further, although the unit cell 110 has the reaction prevention layer 118 in the above embodiment, the unit cell 110 may not have the reaction prevention layer 118 . In the above embodiment, the number of single cells 110 (the number of power generation units 102) included in the fuel cell stack 100 is merely an example, and the number of single cells 110 is the output voltage required for the fuel cell stack 100. can be determined as appropriate. In addition, the materials forming each member in the above-described embodiment are merely examples, and each member may be formed of another material.

Interconnectors 190 and 190A may not contain Cr.

In the interconnectors 190, 190A, each part (the flat plate part 150, the air electrode side current collector part 134, the coating layer 194, the oxide film OC2) may be partially or wholly composed of one member.

Further, the fuel cell stack 100 of the above embodiment is a co-flow type SOFC, but the technique disclosed in this specification is similarly applicable to a counter-type SOFC. Also, the technology disclosed in this specification can be similarly applied to a cross-flow type SOFC.

In addition, the present invention may be applied to a configuration including a metal-supported single cell 110 as described in Japanese Patent Application Laid-Open No. 2018-195414. Also in this configuration, the same effect as the above embodiment can be obtained.

Further, in the above-described embodiment, the target is the fuel cell stack 100 that generates power using the electrochemical reaction between hydrogen contained in the fuel gas and oxygen contained in the oxidant gas, but the present specification discloses The technology is equally applicable to electrolysis cell stacks comprising a plurality of electrolysis single cells, which are the building blocks of a solid oxide electrolysis cell (SOEC) that utilizes the electrolysis reaction of water to produce hydrogen. Note that the basic configuration of the electrolytic cell stack is publicly known as described, for example, in Japanese Patent Application Laid-Open No. 2016-81813, and is approximately as follows. That is, in the configuration of the fuel cell stack 100 of the embodiment described above, the configuration of the electrolysis cell stack is such that the “power generation unit” is replaced with the “electrolysis cell unit”, the “single cell” is replaced with the “electrolysis single cell”, and the “oxidation "oxygen gas supply manifold" should be read as "air discharge manifold", "oxidant gas discharge manifold" should be read as "air supply manifold", "fuel gas supply manifold" should be read as "hydrogen discharge manifold", and "fuel gas discharge manifold" should be read. ” should be read as “water vapor supply manifold”, “oxidant gas supply communication passage” should be read as “air discharge communication passage”, and “oxidant gas discharge communication passage” should be read as “air supply communication passage”. In this configuration, "fuel gas supply communication channel" is read as "hydrogen discharge communication channel", and "fuel gas discharge communication channel" is read as "steam supply communication channel".

During operation of the electrolytic cell stack, a voltage is applied to the electrolytic cell stack such that the air electrode 114 is positive (anode) and the fuel electrode (hydrogen electrode) 116 is negative (cathode). Also, steam as a raw material gas is supplied to the steam supply manifold through the gas passage member 27 . Hydrogen gas may be contained in the water vapor to be supplied. The steam supplied to the steam supply manifold is supplied from the steam supply manifold to the fuel chamber 176 through the steam supply communication channel of each electrolytic cell unit, and subjected to the water electrolysis reaction in each electrolytic single cell. Hydrogen gas generated in the fuel chamber 176 by the electrolysis reaction of water in each electrolysis single cell is discharged to the hydrogen discharge manifold through the hydrogen discharge communication channel together with the surplus water vapor, and is discharged from the hydrogen discharge manifold through the gas passage member 27. It is taken out of the electrolytic cell stack.

Further, during operation of the electrolytic cell stack, air is supplied to the inside of the electrolytic cell stack as necessary in order to control the temperature of the electrolytic cell stack. In this case, the air supplied to the air supply manifold through the gas passage member 27 is supplied to the air chamber 166 from the air supply manifold through the air supply communication channel of each electrolytic cell unit. The air supplied to the air chamber 166 is discharged to the air discharge manifold through the air discharge communication channel together with the oxygen generated at the air electrode 114, and is discharged from the air discharge manifold through the gas passage member 27 to the outside of the electrolytic cell stack. Ejected.

Even in the electrolytic cell stack having such a configuration, by adopting a configuration similar to that of the fuel cell stack 100 in the above embodiment, the same effects as those of the fuel cell stack 100 in the above embodiment can be obtained.

Further, in the above embodiments, a solid oxide fuel cell (SOFC) has been described as an example, but the technology disclosed in this specification can be applied to other types of fuel cells (such as a molten carbonate fuel cell (MCFC)). or electrolytic cell).

10, 10A: fuel cell module 22: bolt 24: nut 26: insulating sheet 27: gas passage member 28: body portion (of gas passage member) 29: branch portion (of gas passage member) 32, 34: hole 61: air Pole-side gas supply channel 71: fuel electrode-side gas supply channel 71P: specific member 71S: specific surface (of fuel electrode-side gas supply channel) 100, 100A: fuel cell stack 102: power generation unit 103: power generation block 104: Upper end plate 106: Lower end plate 108: Communication hole 109: Bolt hole 110: Single cell 112: Electrolyte layer 114: Air electrode 116: Fuel electrode 118: Reaction prevention layer 120: Single cell separator 121: Through hole 124: Joint 125: Glass seal portion 130: Air electrode side frame 131: Hole 132: Air electrode side supply communication channel 133: Air electrode side discharge communication channel 134: Air electrode side current collector 140: Fuel electrode side frame 141: Hole 142: Fuel electrode side supply communication channel 143: Fuel electrode side discharge communication channel 144: Fuel electrode side current collector 145: Electrode facing part (of fuel electrode side current collector) 146: (Fuel electrode side current collector ) Interconnector facing portion 147: Connection portion (of fuel electrode side current collector) 149: Spacer (of fuel electrode side current collector) 150: Flat plate portion (of interconnector) 161: Air electrode side supply manifold 162: Air Pole-side exhaust manifold 166: Air chamber 171: Fuel electrode-side supply manifold 172: Fuel electrode-side exhaust manifold 176: Fuel chamber 180: IC separator 181: Through hole 189: Lower end separator 190, 190A: Interconnector 190S: (inter Specific surface of connector 191: Interconnector separator 194: Coating layer 196: Conductive bonding material 226: Exhaust gas relay channel 228: Mixed gas channel 230: Fuel electrode side gas discharge channel 240: Air electrode side gas discharge flow Path 251: pure water introduction channel 261: raw fuel gas introduction channel 271: air introduction channel 300: auxiliary device 310: evaporator 330: reformer/heater 331: reformer 333: combustor 335: housing 336 : inner wall 337: outer wall 338: air flow path 339: heat transfer fins 350: heat insulating material 351: heat insulating space 400, 400A: specific gas flow path EG: exhaust gas FG: fuel gas FOG: fuel off-gas M1: first material M2: Second material OC1, OC2: Oxide film OG: Oxidant gas OOG: Oxidant off-gas RFG: Raw fuel gas WA: Water

Claims (8)

An electrochemical reactor having 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;
In an electrochemical reaction module in which a specific gas flow path through which a gas supplied to the fuel electrode flows is formed,
At least part of the surface of the specific member, which is a member that defines the specific gas flow path and contains Mn, faces the specific gas flow path and is selected from Mn, Si, Al, Ti and S An oxide film containing a specific element that is at least one element and a specific compound that is a compound of
An electrochemical reaction module characterized by: The electrochemical reaction module according to claim 1,
The oxide film has no MnO identified by X-ray diffraction,
An electrochemical reaction module characterized by: The electrochemical reaction module according to claim 1 or claim 2,
The specific member contains Cr,
An electrochemical reaction module characterized by: The electrochemical reaction module according to any one of claims 1 to 3,
The specific element is Si,
The specific compound is Mn ₂ SiO ₄ , or a compound in which at least one of Mn and Si contained in Mn ₂ SiO ₄ is partially substituted with another element.
An electrochemical reaction module characterized by: The electrochemical reaction module according to any one of claims 1 to 4,
The electrochemical reaction single cell is a fuel cell single cell,
The electrochemical reaction module is a reformer having a space communicating with the specific gas flow path, the reformer reforming the gas supplied to the electrochemical reaction device,
An oxide film containing the specific compound is formed on at least part of a surface of the specific member containing Mn defining a portion between the reformer and the electrochemical reaction device in the specific gas channel. ing,
An electrochemical reaction module characterized by: A method for manufacturing an electrochemical reaction module according to any one of claims 1 to 5,
a preparation step of preparing a first material that is a material of a member that defines the specific gas flow path and contains Mn, and a second material that is a material containing the specific element;
By firing the first material and the second material in a state where the first material and the second material are arranged in the same space in a firing furnace, the specific gas flow a baking step of forming the oxide film on a specific surface that is at least a part of the surface defining the path, and heat-treating a portion of the surface of the first material other than the specific surface;
A method for manufacturing an electrochemical reaction module, characterized by: A method for manufacturing the electrochemical reaction module according to claim 6,
The firing step is a step of performing firing in an air atmosphere.
A method for manufacturing an electrochemical reaction module, characterized by: A method for manufacturing the electrochemical reaction module according to claim 6,
The firing step is a step of firing in an inert atmosphere or in an atmosphere containing hydrogen.
A method for manufacturing an electrochemical reaction module, characterized by:

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