JP7791697B2 - Electrochemical Reaction Unit and Electrochemical Reaction Module - Google Patents

Description

The technology disclosed in this specification relates to electrochemical reaction units and electrochemical reaction modules.

Solid oxide fuel cells (SOFCs) are known as one type of fuel cell that generates electricity using the electrochemical reaction between hydrogen and oxygen. A fuel cell power generation unit (power generation unit), which is a constituent element of an SOFC, includes a single fuel cell cell (single cell) and an interconnector (see, for example, Patent Document 1). The single cell includes an electrolyte layer containing solid oxide, and an air electrode and an anode that face each other in a specific direction (the first direction) across the electrolyte layer. The interconnector is located on the opposite side of the anode from the air electrode in the first direction. The interconnector defines (part of) the fuel chamber that faces the anode. The interconnector is made of ferritic stainless steel. Therefore, the interconnector contains Mn.

JP 2021-086786 A

In the above-mentioned conventional configuration, Mn contained in the interconnector is dispersed into the fuel chamber, increasing the Mn vapor pressure in the fuel chamber, which can adversely affect the performance of the electrochemical reaction unit cell, such as causing cracks in the electrolyte layer.

Note that these issues are also common to electrolysis cell units, which are constituent units of solid oxide electrolysis cells (hereinafter referred to as "SOECs") that generate hydrogen using the electrolysis reaction of water. In this specification, fuel cell units and electrolysis cells are collectively referred to as electrochemical reaction units, and fuel cell power generation units and electrolysis cell units are collectively referred to as electrochemical reaction units. These issues are not limited to SOFCs and SOECs, but are also common to other types of electrochemical reaction units. These issues are also common to electrochemical reaction modules that have electrochemical reaction units and gas flow paths located inside and outside the electrochemical reaction units.

This specification discloses technology that can solve the above-mentioned problems.

The technology disclosed in this specification can be realized, for example, in the following forms:

(1) The electrochemical reaction unit disclosed in this specification comprises an electrochemical reaction unit cell including an electrolyte layer containing a solid oxide, an air electrode and an anode facing each other in a first direction with the electrolyte layer sandwiched therebetween, and an interconnector located on the opposite side of the anode from the air electrode in the first direction, defining a fuel chamber facing the anode and containing Mn, wherein the fuel chamber has a specific flow path portion located in a reaction region where the electrolyte layer, the air electrode, and the anode overlap when viewed in the first direction, and a non-reaction flow path portion located in a non-reaction region not included in the reaction region, and further comprises a specific member containing Si, which is a specific element, and which is located in the non-reaction flow path portion upstream of the flow of gas flowing through the fuel chamber with respect to the specific flow path portion, and at least a portion of which faces the fuel chamber.

In this electrochemical reaction unit, the specific element contained in the specific element is dispersed as a gas into the fuel chamber and reacts with the Mn contained in the interconnector to form a compound of Mn and the specific element. As a result, the Mn contained in the interconnector is prevented from dispersing into the fuel chamber. This is because the Mn becomes a compound with the specific element, making it less likely to disperse into the fuel chamber. In this electrochemical reaction unit, the specific element is located upstream of the gas flow relative to the specific flow path section of the fuel chamber. This makes it possible to particularly efficiently generate the compound of Mn and the specific element on the surface of the interconnector, which is located downstream of the gas flow relative to the specific element. This in turn makes it particularly effective to prevent the Mn contained in the interconnector from dispersing into the fuel chamber. Therefore, with this electrochemical reaction unit, the increase in Mn vapor pressure in the fuel chamber can be particularly effectively suppressed compared to the prior art, thereby improving the performance of the single cell.

(2) The electrochemical reaction unit disclosed in this specification comprises an electrochemical reaction unit cell including an electrolyte layer containing a solid oxide, and an air electrode and an anode facing each other in a first direction across the electrolyte layer, and an interconnector located on the opposite side of the anode from the air electrode in the first direction, defining a fuel chamber facing the anode and containing Mn, wherein the fuel chamber has a specific flow path portion located in a reaction region, which is a region where the electrolyte layer, the air electrode, and the anode overlap when viewed in the first direction, and a non-reaction flow path portion located in a non-reaction region not included in the reaction region, and further comprises a specific component that generates a gas containing a specific element that bonds with Mn contained in the interconnector, and which is located in the non-reaction flow path portion upstream of the flow of gas flowing in the fuel chamber relative to the specific flow path portion, and at least a portion of which faces the fuel chamber. For the same reasons as above, this electrochemical reaction unit, by including a specific component, can more effectively suppress the rise in Mn vapor pressure in the fuel chamber than the conventional technology described above, thereby improving the performance of the single cell.

In this electrochemical reaction unit, the specific element contained in the specific element is dispersed as a gas into the fuel chamber and reacts with the Mn contained in the interconnector to form a compound of Mn and the specific element. As a result, the Mn contained in the interconnector is prevented from dispersing into the fuel chamber. This is because the Mn becomes a compound with the specific element, making it less likely to disperse into the fuel chamber. In this electrochemical reaction unit, the specific element is located upstream of the gas flow relative to the specific flow path section of the fuel chamber. This makes it possible to particularly efficiently generate the compound of Mn and the specific element on the surface of the interconnector, which is located downstream of the gas flow relative to the specific flow path section. This in turn makes it particularly effective to prevent the Mn contained in the interconnector from dispersing into the fuel chamber. Therefore, with this electrochemical reaction unit, the increase in Mn vapor pressure in the fuel chamber can be particularly effectively suppressed compared to the prior art, thereby improving the performance of the single cell.

(3) In the above electrochemical reaction unit, the content of the specific element in the specific component may be 10 mass% or more. This electrochemical reaction unit can more effectively suppress an increase in Mn vapor pressure in the fuel chamber, thereby improving the performance of the single cell.

(4) In the above electrochemical reaction unit, the specific component may have the specific element bonded to a hydroxyl group. This electrochemical reaction unit can more effectively suppress an increase in Mn vapor pressure in the fuel chamber, thereby improving the performance of the single cell.

(5) In the above electrochemical reaction unit, at least a portion of the specific member may be accommodated in a groove formed in a portion of the interconnector that defines the non-reaction flow path portion. This electrochemical reaction unit allows the specific member to be positioned, and also prevents the specific member from interfering with the flow of gas in the fuel chamber, compared to a configuration in which the specific member is not accommodated in a groove of the interconnector.

(6) In the above electrochemical reaction unit, the electrochemical reaction unit may be configured to include a plurality of the specific components, and the multiple specific components may be spaced apart from each other in a direction intersecting the flow of gas through the fuel chamber. In this electrochemical reaction unit, compared to a configuration including only one specific component, the Mn contained in the interconnector can be more effectively prevented from scattering into the fuel chamber. Furthermore, even though the electrochemical reaction unit includes multiple specific components, the multiple specific components are spaced apart from each other in the above direction (the direction intersecting the flow of gas through the fuel chamber), which makes it possible to relatively effectively prevent the specific components from obstructing the flow of gas.

(7) In the above electrochemical reaction unit, the interconnector may contain Cr. In this electrochemical reaction unit, a compound containing Cr is formed on the surface of the interconnector. Furthermore, a compound of Mn and a specific element formed on the surface of the interconnector serves as a nucleus to form a compound of Mn and Cr with a low Mn vapor pressure, thereby further suppressing Mn from scattering into the fuel chamber. Therefore, this electrochemical reaction unit can more effectively suppress an increase in Mn vapor pressure in the fuel chamber, thereby improving the performance of the single cell.

(8) The electrochemical reaction module disclosed in this specification is an electrochemical reaction module having an electrochemical reaction unit including an electrochemical reaction unit cell including an electrolyte layer containing a solid oxide, an air electrode and an anode facing each other in a first direction across the electrolyte layer, and an interconnector located on the opposite side of the anode from the air electrode in the first direction, defining a fuel chamber facing the anode and containing Mn, the electrochemical reaction module including a first flow path portion that is a gas flow path located inside the electrochemical reaction unit and including the fuel chamber, and a second flow path portion, which is a gas flow path located outside the electrochemical reaction unit and is in communication with the first flow path portion on the upstream side of the gas flow relative to the first flow path portion, and when a portion of the fuel chamber located in a reaction region where the electrolyte layer, the air electrode, and the anode overlap as viewed in the first direction is defined as a specific flow path portion, the electrochemical reaction module further comprises a specific gas supply portion located upstream of the specific flow path portion in at least one of the first flow path portion and the second flow path portion, which supplies a gas containing Si, a specific element, to the specific flow path portion. In this electrochemical reaction module, the gas containing the specific element is supplied to the specific flow path portion of the fuel chamber by the specific gas supply portion, and reacts with Mn contained in the interconnector to generate a compound of Mn and the specific element, thereby suppressing scattering of Mn contained in the interconnector into the fuel chamber. By positioning the specific gas supply unit upstream of the specific flow path unit in the gas flow direction, the above-mentioned compound of Mn and the specific element can be particularly efficiently produced on the surface of the interconnector, which is located downstream of the specific gas supply unit in the gas flow direction, and therefore, the Mn contained in the interconnector is particularly effectively prevented from scattering into the fuel chamber. Therefore, with this electrochemical reaction module, the increase in Mn vapor pressure in the fuel chamber can be particularly effectively suppressed compared to the above-mentioned conventional technology, thereby improving the performance of the single cell.

The technology disclosed in this specification can be realized in various forms, such as an electrochemical reaction unit (fuel cell power generation unit or electrolysis cell unit), its manufacturing method, etc.

FIG. 1 is a perspective view showing the external configuration of a fuel cell stack 100 according to a first embodiment; FIG. 2 is an explanatory diagram showing the XZ cross-sectional configuration of the fuel cell stack 100 taken along the line II-II in FIG. 1. FIG. 2 is an explanatory diagram showing the XZ cross-sectional configuration of the fuel cell stack 100 taken along the line III-III in FIG. 1. FIG. 4 is an explanatory diagram showing the YZ cross-sectional structure of the fuel cell stack 100 taken along the line IV-IV in FIG. FIG. 3 is an explanatory diagram showing the XZ cross-sectional configuration of two adjacent power generating units 102 at the same position as the cross-section shown in FIG. 2 . FIG. 4 is an explanatory diagram showing the XZ cross-sectional configuration of two adjacent power generating units 102 at the same position as the cross-section shown in FIG. 3 . FIG. 5 is an explanatory diagram showing the YZ cross-sectional configuration of two adjacent power generating units 102 at the same position as the cross-section shown in FIG. FIG. 8 is an explanatory diagram showing the XY cross-sectional structure of the power generating unit 102 at the position VIII-VIII in FIGS. 5 to 7. FIG. 8 is an explanatory diagram showing the XY cross-sectional configuration of the power generating unit 102 at the position IX-IX in FIGS. 5 to 7. FIG. 8 is an explanatory diagram showing the XY cross-sectional structure of the power generating unit 102 taken along the line XX in FIGS. 5 to 7. FIG. 10 is an explanatory diagram illustrating a schematic configuration of a fuel cell module 10 according to a second embodiment.

A. First embodiment:
A-1. Configuration of fuel cell stack 100:
FIG. 1 is a perspective view showing the external configuration of a fuel cell stack 100 according to a first embodiment. FIG. 2 is an explanatory diagram showing an XZ cross-sectional configuration of the fuel cell stack 100 taken along line II-II in FIG. 1 (and FIGS. 8 to 10). FIG. 3 is an explanatory diagram showing an XZ cross-sectional configuration of the fuel cell stack 100 taken along line III-III in FIG. 1 (and FIGS. 8 to 10). FIG. 4 is an explanatory diagram showing a YZ cross-sectional configuration of the fuel cell stack 100 taken along line IV-IV in FIG. 1. Each figure shows orthogonal X, Y, and Z axes for specifying directions. For convenience, the positive Z-axis direction will be referred to as the upward direction and the negative Z-axis direction as the downward direction in this specification. However, the fuel cell stack 100 may actually be installed in an orientation different from these orientations. The same applies to FIG. 5 and subsequent figures.

The fuel cell stack 100 includes a plurality (seven in this embodiment) of fuel cell power generation units (hereinafter simply referred to as "power generation units") 102, a lower separator 189, and a pair of end plates 104, 106. The seven power generation units 102 are arranged in a predetermined arrangement direction (vertical direction in this embodiment). One of the pair of end plates 104, 106 (hereinafter referred to as the "upper end plate 104") is arranged above the assembly (hereinafter referred to as the "power generation block 103") made up of the seven power generation units 102, and the other of the pair of end plates 104, 106 (hereinafter referred to as the "lower end plate 106") is arranged below the lower separator 189. The pair of end plates 104, 106 are arranged to sandwich the power generation block 103 from above and below. Note that the arrangement direction (Z-axis direction, vertical direction) is an example of the first direction in the claims.

As shown in Figures 1 and 4, holes that penetrate each layer in the vertical direction are formed near the four corners of the outer periphery around the Z-axis of each layer (upper end plate 104, each power generating unit 102, and lower end separator 189) that make up the fuel cell stack 100, and holes (screw holes) are formed in the upper surface of the lower end plate 106 near the four corners of its outer periphery around the Z-axis. Corresponding holes formed in these layers are vertically connected to form bolt holes 109 that extend in the vertical direction. In the following description, the holes formed in each layer of the fuel cell stack 100 to form bolt holes 109 may also be referred to as bolt holes 109.

A bolt 22 is inserted into each bolt hole 109. The lower end of each bolt 22 threads into a threaded hole formed in the lower end plate 106, and a nut 24 is fitted onto the upper end of each bolt 22. The lower surface of the nut 24 abuts against the upper surface of the end plate 104 via an insulating sheet 26. The bolts 22 and nuts 24 configured in this way fasten the layers of the fuel cell stack 100 together. The insulating sheet 26 is made of, for example, a mica sheet, ceramic fiber sheet, ceramic powder sheet, glass sheet, glass ceramic composite, etc.

As shown in Figures 1 to 3, four holes that penetrate each layer in the vertical direction are formed in the peripheral portion around the Z axis direction of each layer (each power generation unit 102, lower-end separator 189, lower end plate 106) that make up the fuel cell stack 100, and corresponding holes formed in each layer are vertically connected to each other to form communication holes 108 that extend vertically from the uppermost power generation unit 102 to the lower 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.

1 and 2, one communication hole 108 located near one side (the side on the positive X-axis of the two sides parallel to the Y-axis) that constitutes the outer periphery of the fuel cell stack 100 around the Z-axis functions as an oxidant gas supply manifold 161, which is a gas flow path through which oxidant gas OG is introduced from outside the fuel cell stack 100 and supplied to the air chamber 166 (described later) of each power generation unit 102. Another communication hole 108 located near the opposite side (the side on the negative X-axis of the two sides parallel to the Y-axis) functions as an oxidant gas discharge manifold 162, which is a gas flow path through which oxidant off-gas OOG, which is gas discharged from the air chamber 166 of each power generation unit 102, is discharged to the outside of the fuel cell stack 100. Note that air, for example, is used as the oxidant gas OG.

1 and 3, among the sides constituting the outer periphery of the fuel cell stack 100 around the Z axis, another communication hole 108 located near the side closest to the communication hole 108 functioning as the oxidant gas exhaust manifold 162 described above functions as a fuel gas supply manifold 171, which is a gas flow path through which fuel gas FG is introduced from outside the fuel cell stack 100 and supplied to the fuel chamber 176 (described later) of each power generation unit 102. The other communication hole 108 located near the side closest to the communication hole 108 functioning as the oxidant gas supply manifold 161 described above functions as a fuel gas exhaust manifold 172, which is a gas flow path through which fuel off-gas FOG, which is gas exhausted from the fuel chamber 176 of each power generation unit 102, is exhausted to the outside of the fuel cell stack 100. The fuel gas FG may be, for example, a hydrogen-rich gas obtained by reforming city gas.

2 and 3, the fuel cell stack 100 is provided with four gas passage members 27. Each gas passage member 27 has a hollow cylindrical main body 28 and a hollow cylindrical branch portion 29 branching off from the side of the main body 28. The holes in the branch portion 29 are connected to the holes in the main body 28. A gas pipe (not shown) is connected to the branch portion 29 of each gas passage member 27. As shown in FIG. 2, the hole in the main body 28 of the gas passage member 27 positioned at the position of the oxidant gas supply manifold 161 is connected to the oxidant gas supply manifold 161, and the hole in the main body 28 of the gas passage member 27 positioned at the position of the oxidant gas discharge manifold 162 is connected to the oxidant gas discharge manifold 162. As shown in FIG. 3 , the holes in the main body 28 of the gas passage member 27 positioned at the position of the fuel gas supply manifold 171 are connected to the fuel gas supply manifold 171, and the holes in the main body 28 of the gas passage member 27 positioned at the position of the fuel gas exhaust manifold 172 are connected to the fuel gas exhaust 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)
The pair of end plates 104, 106 are flat, plate-shaped members with a substantially rectangular outer shape as viewed in the Z-axis direction, and are made of a conductive material such as stainless steel. Holes 32, 34 are formed near the centers of the pair of end plates 104, 106, respectively, penetrating in the Z-axis direction. As viewed in the Z-axis direction, the outlines of the holes 32, 34 formed in each of the pair of end plates 104, 106 encompass each of the unit cells 110 (described later). Therefore, the fastening force (compressive force in the Z-axis direction) of each bolt 22 and nut 24 acts primarily on the periphery of each power generating unit 102 (the portion outside the unit cells 110 (described later)). 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.

(Configuration of the lower end separator 189)
The lower-end separator 189 is a flat member having a substantially rectangular outer shape when viewed in the Z-axis direction, and is made of, for example, metal. The peripheral edge 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 welding, for example, and is electrically connected to the lower end plate 106.

(Configuration of power generation unit 102)
Fig. 5 is an explanatory diagram showing the XZ cross-sectional configuration of two adjacent power generating units 102 at the same position as the cross-section shown in Fig. 2, Fig. 6 is an explanatory diagram showing the XZ cross-sectional configuration of two adjacent power generating units 102 at the same position as the cross-section shown in Fig. 3, and Fig. 7 is an explanatory diagram showing the YZ cross-sectional configuration of two adjacent power generating units 102 at the same position as the cross-section shown in Fig. 4. Also, Fig. 8 is an explanatory diagram showing the XY cross-sectional configuration of the power generating unit 102 at the position VIII-VIII in Figs. 5 to 7, Fig. 9 is an explanatory diagram showing the XY cross-sectional configuration of the power generating unit 102 at the position IX-IX in Figs. 5 to 7, and Fig. 10 is an explanatory diagram showing the XY cross-sectional configuration of the power generating unit 102 at the position X-X in Figs. 5 to 7.

As shown in Figures 5 to 7, the power generation unit 102 includes a single fuel cell (hereinafter referred to as a "single cell") 110, a single cell separator 120, an air electrode side frame 130, an anode side frame 140, an anode side current collector 144, a spacer 149, and a pair of interconnectors 190 that form the top and bottom layers of the power generation unit 102. Holes that form the communication holes 108 that function as the manifolds 161, 162, 171, and 172, and holes that form the bolt holes 109, are formed around the peripheral edges of the single cell separator 120, the air electrode side frame 130, the anode side frame 140, and the interconnector 190 (more specifically, the IC separator 180, described later) around the Z axis direction.

The unit cell 110 includes an electrolyte layer 112, an air electrode 114 and an anode 116 that face each other in the Z-axis direction with the electrolyte layer 112 sandwiched between them, and a reaction prevention layer 118 disposed between the electrolyte layer 112 and the air electrode 114. Note that the unit cell 110 of this embodiment is an anode-supported unit cell in which the anode 116 supports the other layers that make up the unit cell 110 (electrolyte layer 112, air electrode 114, and reaction prevention layer 118).

The electrolyte layer 112 is a substantially rectangular, flat-plate member when viewed in the Z-axis direction and is configured to contain a solid oxide (e.g., YSZ (yttria-stabilized zirconia)). That is, the unit cell 110 of this embodiment is a solid oxide fuel cell (SOFC) that uses a solid oxide as an electrolyte. The air electrode 114 is a substantially rectangular, flat-plate member that is smaller than the electrolyte layer 112 when viewed in the Z-axis direction and is configured to contain, for example, a perovskite-type oxide (e.g., LSCF (lanthanum strontium cobalt iron oxide)). The anode 116 is a substantially rectangular, flat-plate member that is 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. The reaction prevention layer 118 is a substantially rectangular, flat-plate member that is 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 has the function of preventing elements (e.g., Sr) diffused from the cathode 114 from reacting with elements (e.g., Zr) contained in the electrolyte layer 112 to produce a highly resistive substance (e.g., SrZrO ₃ ).

The single cell separator 120 is a frame-shaped conductive member formed with a substantially rectangular through-hole 121 penetrating vertically near the center, and is made of, for example, metal. The plate thickness of the single cell separator 120 is relatively thin, for example, between 0.05 mm and 0.2 mm. The portion of the single cell separator 120 surrounding the through-hole 121 (hereinafter referred to as the "through-hole surrounding portion") faces the upper surface of the peripheral portion of the single cell 110 (electrolyte layer 112). The single cell separator 120 is joined to the single cell 110 (electrolyte layer 112) by a joint 124 formed with brazing material (e.g., Ag brazing) placed in the facing portion. Therefore, the single cell separator 120 can be said to be connected to the single cell 110 via the joint 124. The single cell separator 120 separates the air chamber 166 facing the air electrode 114 from the fuel chamber 176 facing the fuel electrode 116, thereby preventing gas leakage (cross leakage) from one electrode side to the other around the periphery of the single cell 110.

The single-cell separator 120 includes an inner portion 126 that includes the area surrounding the through-holes in the single-cell separator 120, an outer portion 127 that is located outside the inner portion 126, and a connecting portion 128 that connects the inner portion 126 and the outer portion 127. In this embodiment, the inner portion 126 and the outer portion 127 are generally flat plates that extend in a direction generally perpendicular to the Z-axis direction. The connecting portion 128 is curved so that it protrudes downward relative to both the inner portion 126 and the outer portion 127. The lower portion of the connecting portion 128 (facing the fuel chamber 176) is a convex portion, and the upper portion of the connecting portion 128 (facing the air chamber 166) is a concave portion. Therefore, the connecting portion 128 includes portions whose positions in the Z-axis direction differ from those of the inner portion 126 and the outer portion 127.

A glass seal portion 125 containing glass is disposed near the through-hole 121 in the single-cell separator 120. The glass seal portion 125 is located on the air chamber 166 side of the joint portion 124 and is formed so as to contact both the surface surrounding the through-hole in the single-cell separator 120 and the surface of the single cell 110 (electrolyte layer 112 in this embodiment). The glass seal portion 125 effectively prevents gas leakage (cross leakage) from one electrode side to the other electrode side at the periphery of the single cell 110.

The interconnector 190 is a conductive member having a substantially rectangular flat plate portion 150, multiple substantially columnar air electrode-side current collectors 134 protruding from the flat plate portion 150 toward the air electrode 114, and an IC separator 180. It is formed of a metal (e.g., ferritic stainless steel) containing Mn (manganese) and Cr (chromium). The interconnector 190 defines (a portion of) the fuel chamber 176 facing the fuel electrode 116. In this embodiment, a conductive coating layer 194, composed of, for example, a spinel-type oxide, is formed on the surfaces of the flat plate portion 150 and the air electrode-side current collectors 134 of the interconnector 190 (the surfaces facing the air chamber 166). Hereinafter, the interconnector 190 with the coating layer 194 formed thereon will be simply referred to as the "interconnector 190." In each power generation unit 102, the upper interconnector 190 (the flat plate portion 150 thereof) is positioned above the single cell 110. The upper interconnector 190 (each of its air electrode-side current collectors 134) is joined to the air electrode 114 of the unit cell 110 via a conductive bonding material 196 made of, for example, a spinel-type oxide, and is thereby electrically connected to the air electrode 114 of the unit cell 110. In each power generation unit 102, the lower interconnector 190 is disposed below the unit cell 110, with the fuel chamber 176 sandwiched between them, and is electrically connected to the anode 116 of the unit cell 110 via an anode-side current collector 144 (described later). The interconnector 190 ensures electrical conduction between the power generation units 102 and suppresses mixing of reactant gases between the power generation units 102. In this embodiment, when two power generation units 102 are disposed adjacent to each other, one interconnector 190 is shared by the two adjacent power generation units 102. That is, the upper interconnector 190 of one power generating unit 102 is made of the same material as the lower interconnector 190 of another power generating unit 102 adjacent to the upper side of that power generating unit 102. Each interconnector 190 constituting a power generating unit 102 is located on the opposite side of the fuel electrode 116 from the air electrode 114 in the Z-axis direction. In addition, because the fuel cell stack 100 includes a lower-end separator 189, the power generating unit 102 located at the bottom of the fuel cell stack 100 does not include a lower interconnector 190 (see Figures 2 to 4).

The IC separator 180 is a frame-shaped member formed of, for example, metal, with a substantially rectangular through-hole 181 penetrating vertically near the center. The plate thickness of the IC separator 180 is relatively thin, for example, between 0.05 mm and 0.2 mm. The IC separator 180 faces the single cell separator 120 in the Z-axis direction. The portion of the IC separator 180 surrounding the through-hole 181 (hereinafter referred to as the "through-hole surrounding portion") is joined, for example, by welding, to the upper surface of the peripheral portion of the flat portion 150 of the interconnector 190. Of a pair of IC separators 180 included in a certain power generating unit 102, the upper IC separator 180 separates the air chamber 166 of that power generating unit 102 from the fuel chamber 176 of the other power generating unit 102 adjacent to the power generating unit 102 on the upper side. Furthermore, of the pair of IC separators 180 included in a certain power generating unit 102, the lower IC separator 180 separates the fuel chamber 176 of that power generating unit 102 from the air chamber 166 of the other power generating unit 102 adjacent to that power generating unit 102 on the lower side. In this way, the IC separator 180 suppresses gas leakage between the power generating units 102 at the periphery of the power generating units 102. The IC separator 180 of the upper interconnector 190 of the power generating unit 102 located at the topmost position in the fuel cell stack 100 is electrically connected to the upper end plate 104.

The IC separator 180 comprises an inner portion 186 including the through-hole periphery, an outer portion 187 located outside the inner portion 186, and a connecting portion 188 connecting the inner portion 186 and the outer portion 187. In this embodiment, the inner portion 186 and the outer portion 187 are generally flat plates extending in a direction generally perpendicular to the Z-axis direction. The connecting portion 188 is curved so as to protrude downward relative to both the inner portion 186 and the outer portion 187. The lower portion of the connecting portion 188 (toward the air chamber 166) is a convex portion, and the upper portion of the connecting portion 188 (toward the fuel chamber 176) is a concave portion. Therefore, the connecting portion 188 includes a portion whose position in the Z-axis direction differs from that of the inner portion 186 and the outer portion 187.

As shown in Figures 5 to 8, the air electrode side frame 130 is a frame-shaped member with a substantially rectangular hole 131 formed near the center that penetrates in the Z-axis direction, and is formed from an insulating material such as mica. The hole 131 in the air electrode side frame 130 forms (part of) the air chamber 166 facing the air electrode 114. The air electrode side frame 130 is in contact with the upper surface of the peripheral portion of the single cell separator 120 and the lower surface of the peripheral portion of the upper IC separator 180, and functions as a sealing member that ensures gas sealing between the two (i.e., gas sealing of the air chamber 166). The air electrode side frame 130 also provides electrical insulation between a pair of IC separators 180 (i.e., between a pair of interconnectors 190) included in the power generation unit 102. The air electrode side frame 130 is also formed with an oxidant gas supply communication channel 132 that connects the oxidant gas supply manifold 161 to the air chamber 166, and an oxidant gas discharge communication channel 133 that connects the air chamber 166 to the oxidant gas discharge manifold 162.

As shown in Figures 5 to 7, 9, and 10, the fuel electrode side frame 140 is a frame-shaped member with a substantially rectangular hole 141 formed near the center that penetrates in the Z-axis direction, and is made of, for example, metal. The hole 141 in 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 lower surface of the peripheral portion of the single cell separator 120 and the upper surface of the peripheral portion of the lower IC separator 180.

As shown in FIG. 10 , the fuel chamber 176 has a specific flow path portion 176A located in the region RA where the electrolyte layer 112, air electrode 114, and fuel electrode 116 overlap when viewed in the Z-axis direction (hereinafter referred to as the "reaction region"), and a non-reaction flow path portion 176B located in the region UA not included in the reaction region RA (hereinafter referred to as the "non-reaction region"). The reaction region RA is the region where the power generation reaction mainly occurs and has a relatively large contribution to power generation, while the non-reaction region UA is a region where the power generation reaction is less likely to occur and has a relatively small contribution to power generation. In this embodiment, when viewed in the Z-axis direction, the reaction region RA is located in the center of the single cell 110, and the non-reaction region UA is located so as to surround the periphery of the reaction region RA.

The fuel electrode side frame 140 also has a fuel gas supply communication channel 142 that connects the fuel gas supply manifold 171 to the fuel chamber 176, and a fuel gas discharge communication channel 143 that connects the fuel chamber 176 to the fuel gas discharge manifold 172.

As shown in Figures 5 to 7, the fuel electrode side current collector 144 is disposed within the fuel chamber 176. The fuel electrode side current collector 144 is located between the unit cell 110 and the interconnector 190.

As shown in FIG. 7 , the fuel electrode side current collector 144 has an electrode side contact portion 145, an opposite side contact portion 146, a connecting portion 147, and a Y-direction tip portion 148. The electrode side contact portion 145 contacts the fuel electrode 116 and contacts a spacer 149 on the side opposite the fuel electrode 116. The opposite side contact portion 146 contacts the interconnector 190 (more precisely, the lower interconnector 190 of the pair of interconnectors 190). However, as described above, the power generating unit 102 located at the bottom of the fuel cell stack 100 does not have a lower interconnector 190, and therefore the opposite side contact portion 146 of that power generating unit 102 contacts the lower end separator 189. The connecting portion 147 connects the electrode side contact portion 145 and the opposite side contact portion 146. The Y-direction tip portion 148 is connected to the electrode-side contact portion 145 on the side opposite to the side connected to the connecting portion 147 (the negative Y-axis side). The anode-side current collector 144 has such a configuration, and electrically connects the anode 116 and the interconnector 190 (or the lower-end separator 189). A rod-shaped spacer 149 made of, for example, mica is disposed between the electrode-side contact portion 145 and the lower-end contact portion 146 of the anode-side current collector 144. This allows the anode-side current collector 144 to follow deformation of the power generating unit 102 due to temperature cycles and fluctuations in reactant gas pressure, and good electrical connection between the anode 116 and the interconnector 190 (or the lower-end separator 189) via the anode-side current collector 144 is maintained. The spacer 149 is covered by the Y-direction tip 148 of the fuel electrode side current collector 144, the electrode side contact portion 145, the connecting portion 147, and the opposite side contact portion 146. This prevents the spacer 149 from shifting out of position.

Each power generating unit 102 has multiple joints 151 that join the Y-direction tip 148 of the fuel electrode side current collector 144 to the interconnector 190. The joints 151 are weld marks formed by welding (e.g., spot welding using a laser) the Y-direction tip 148 of the fuel electrode side current collector 144 to the interconnector 190.

As shown in Figures 5 and 6, the fuel electrode side current collector 144 further includes an X-direction tip portion 148A and an X-direction tip portion 148B. The two X-direction tips 148A, 148B are connected to one end (negative X-axis direction) and the other end (positive X-axis direction) of the electrode side contact portion 145, respectively. The spacer 149 is covered by the Y-direction tip portion 148 of the fuel electrode side current collector 144, the electrode side contact portion 145, the opposite side contact portion 146, and the two X-direction tips 148A, 148B. This prevents the spacer 149 from shifting out of position.

In this embodiment, the opposite side contact portion 146, electrode side contact portion 145, connecting portion 147, Y-direction tip portion 148, X-direction tip portion 148A, and X-direction tip portion 148B of the fuel electrode side current collector 144 are formed as a single member.

In this embodiment, the fuel electrode-side current collector 144 is formed from a metal foil (e.g., having a thickness of 10 to 800 μm) made of, for example, nickel, a nickel alloy, stainless steel, etc. As shown in the partially enlarged view of FIG. 9 , the fuel electrode-side current collector 144 is manufactured by cutting a substantially rectangular metal foil and bending and raising a plurality of rectangular portions.
A-2. Operation of the fuel cell stack 100:
2 and 5, when 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 supply manifold 161, the oxidant gas OG is supplied to the oxidant gas supply manifold 161 through the branch portion 29 of the gas passage member 27 and a hole in the main body 28, and then supplied from the oxidant gas supply manifold 161 to the air chamber 166 through the oxidant gas supply communicating passage 132 of each power generating unit 102. Also, as shown in FIGS. 3 and 6, when 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 supply manifold 171, the fuel gas FG is supplied to the fuel gas supply manifold 171 through the branch portion 29 of the gas passage member 27 and a hole in the main body 28, and then supplied from the fuel gas supply manifold 171 to the fuel chamber 176 through the fuel gas supply communicating passage 142 of each power generating unit 102.

When oxidant gas OG is supplied to the air chamber 166 of each power generation unit 102 and fuel gas FG is supplied to the fuel chamber 176, power is generated in the single cell 110 through an electrochemical reaction between the oxidant gas OG and the fuel gas FG. This power generation reaction is exothermic. In each power generation unit 102, the air electrode 114 of the single cell 110 is electrically connected to the upper interconnector 190, and the anode 116 is electrically connected to the lower interconnector 190 (or the lower separator 189) via the anode-side current collector 144. In other words, the multiple power generation units 102 included in the fuel cell stack 100 are electrically connected in series. The upper interconnector 190 of the uppermost power generation unit 102 is electrically connected to the upper end plate 104, and the lower separator 189 electrically connected to the anode-side current collector 144 of the lowermost power generation unit 102 is electrically connected to the lower end plate 106. Therefore, electrical energy generated in each power generation unit 102 is extracted from end plates 104, 106, which function as output terminals of the fuel cell stack 100. Note that, because SOFCs generate electricity at relatively high temperatures (e.g., 700°C to 1000°C), after startup, the fuel cell stack 100 may be heated by a heater (not shown) until the heat generated by power generation can maintain the high temperature.

As shown in FIGS. 2 and 5, the oxidant off-gas OOG discharged from the air chamber 166 of each power generating unit 102 to the oxidant gas discharge manifold 162 via the oxidant gas discharge communicating channel 133 passes through holes in the main body 28 and branch portion 29 of the gas passage member 27 located at the position of the oxidant gas discharge manifold 162, and is then discharged to the outside of the fuel cell stack 100 via a gas pipe (not shown) connected to the branch portion 29. Also, as shown in FIGS. 3 and 6, the fuel off-gas FOG discharged from the fuel chamber 176 of each power generating unit 102 to the fuel gas discharge manifold 172 via the fuel gas discharge communicating channel 143 passes through holes in the main body 28 and branch portion 29 of the gas passage member 27 located at the position of the fuel gas discharge manifold 172, and is then discharged to the outside of the fuel cell stack 100 via a gas pipe (not shown) connected to the branch portion 29.

In the fuel cell stack 100 of this embodiment, as shown in Figures 8 and 10, when viewed in the Z-axis direction, the oxidant gas supply communication passage 132 communicating with the oxidant gas supply manifold 161 and the fuel gas discharge communication passage 143 communicating with the fuel gas discharge manifold 172 are arranged to face (in the same direction) one side of the unit cell (the second side SI2 shown in Figures 8 and 10), and the oxidant gas discharge communication passage 133 communicating with the oxidant gas discharge manifold 162 and the fuel gas supply communication passage 142 communicating with the fuel gas supply manifold 171 are arranged to face (in the same direction) another side (the first side SI1 shown in Figures 8 and 10) opposite the second side SI2 of the unit cell across the center point of the unit cell 110. That is, the power generation unit 102 (fuel cell stack 100) of this embodiment is a counterflow type SOFC in which the main flow direction of oxidant gas OG in the air chamber 166 (direction from the positive X-axis to the negative X-axis) and the main flow direction of fuel gas FG in the fuel chamber 176 (direction from the negative X-axis to the positive X-axis) are substantially opposite (facing each other).

A-3. Configuration of specific member 50:
5, 6 and 10, the power generating unit 102 further includes a plurality of (six in this embodiment) specific members 50. The configuration of the specific members 50 will be described below.

The specific member 50 is a rectangular parallelepiped member (for example, mica) containing Si (silicon). Si corresponds to an element (hereinafter referred to as the "specific element") that bonds with Mn contained in the interconnector 190. Note that mica contains Si bonded to a hydroxyl group (OH). Furthermore, the fact that the specific member 50 contains the specific element (Si) bonded to a hydroxyl group (OH) can be confirmed by a method of identifying a crystalline phase using X-ray diffraction (XRD) or by detecting a hydroxyl group bond peak (for example, a peak at 3600 to 3800 cm ^-1 in the case of a Si-OH bond) using Fourier transform infrared spectroscopy (FT-IR).

At least a portion of each specific member 50 faces the fuel chamber 176. Therefore, when the fuel cell stack 100 is in operation, the specific element (Si) contained in the specific member 50 disperses as a gas into the fuel chamber 176. Therefore, the specific member 50 is a member that generates a gas containing the specific element (Si).

The height (width in the Z-axis direction) of each specific member 50 is, for example, 10 μm or more and 5 mm or less. The width in the X-axis or Y-axis direction of each specific member 50 is, for example, 1 mm or more and 500 mm or less.

The content of the specific element (Si) in each specific component 50 is 10% by mass or more (for example, 21% by mass in the case of muscovite). The content of the specific element (Si) in the specific component 50 can be measured by performing ICP optical emission analysis on a sample obtained by dissolving the specific component 50 using nitric acid or the like.

As shown in Figures 5 and 6, the specific member 50 is placed on the IC separator 180 of the interconnector 190, which defines the non-reaction flow path portion 176B of the fuel chamber 176. The specific member 50 is joined to the IC separator 180 of the interconnector 190 by welding or the like. A groove portion 191 is formed in the IC separator 180 of the interconnector 190, and at least a portion of the specific member 50 is accommodated in the groove portion 191 of the interconnector 190. Note that, although the entire specific member 50 may be accommodated in the groove portion 191 of the interconnector 190 as shown in Figures 5 and 6, only a portion of the specific member 50 may be accommodated in the groove portion 191 of the interconnector 190.

As shown in FIG. 10, the multiple (six) specific members 50 provided in each power generation unit 102 are located upstream of the specific flow path section 176A in the non-reaction flow path section 176B of the fuel chamber 176 in the flow of fuel gas FG.

The multiple (six) specific members 50 provided in each power generation unit 102 are spaced apart from one another in a direction (Y-axis direction) that intersects the flow of fuel gas FG. As shown in FIG. 10, the multiple (six) specific members 50 may be arranged linearly in the direction (Y-axis direction) that intersects the flow of fuel gas FG, or they may be arranged in a non-linear manner (e.g., curved) and spaced apart from one another in the direction (Y-axis direction) that intersects the flow of fuel gas FG.

A-4. Advantages of the first embodiment:
As described above, the fuel cell stack 100 of this embodiment includes a power generation unit 102. The power generation unit 102 includes a single cell 110 and an interconnector 190. The single cell 110 includes an electrolyte layer 112 containing a solid oxide, and a cathode 114 and an anode 116 that face each other in the Z-axis direction with the electrolyte layer 112 sandwiched therebetween. The interconnector 190 is located on the opposite side of the anode 116 from the cathode 114 in the Z-axis direction. The interconnector 190 defines a fuel chamber 176 facing the anode 116 and contains Mn. The fuel chamber 176 has a specific flow path portion 176A located in a reaction region RA, which is a region where the electrolyte layer 112, the cathode 114, and the anode 116 overlap when viewed in the Z-axis direction, and a non-reaction flow path portion 176B located in a non-reaction region UA that is not included in the reaction region RA. The power generation unit 102 includes a specific member 50 containing a specific element (Si). The specific member 50 corresponds to a member that generates a gas containing a specific element (Si). The specific member 50 is located in the non-reaction flow path section 176B upstream of the flow of fuel gas FG (gas flowing in the fuel chamber 176) relative to the specific flow path section 176A. At least a portion of the specific member 50 faces the fuel chamber 176.

In the power generating unit 102 of this embodiment, since it is provided with the above-mentioned specific component 50, the specific element (Si) contained in the specific component 50 is dispersed as a gas into the fuel chamber 176 and reacts with the Mn contained in the interconnector 190 to produce a compound of Mn and the specific element (Si) (such as Mn ₂ SiO ₄ (manganese silicate)), and as a result, the Mn contained in the interconnector 190 is prevented from scattering into the fuel chamber 176. This is because Mn becomes a compound with the specific element (Si), making it less likely to scatter into the fuel chamber 176. In the power generating unit 102 of this embodiment, the specific member 50 is located upstream of the flow of gas (fuel gas FG) with respect to the specific flow path section 176A of the fuel chamber 176, and this makes it possible to particularly efficiently produce the compound of Mn and the specific element (Si) described above on the surface of the interconnector 190 located downstream of the flow of gas (fuel gas FG) with respect to the specific member 50, and thus particularly effectively suppresses the Mn contained in the interconnector 190 from scattering into the fuel chamber 176. Therefore, according to the power generating unit 102 of this embodiment, an increase in Mn vapor pressure in the fuel chamber 176 can be particularly effectively suppressed compared to the conventional technology, thereby enabling the performance of the unit cell 110 to be improved.

In the power generating unit of this embodiment, the content of the specific element (Si) in the specific component 50 is 10 mass% or more. Therefore, with the power generating unit 102 of this embodiment, the increase in Mn vapor pressure in the fuel chamber 176 can be more effectively suppressed, thereby improving the performance of the unit cell 110.

In the power generation unit of this embodiment, the specific component 50 has a specific element (Si) bonded to a hydroxyl group (OH group). The specific element is more likely to generate a gas containing the specific element when it is bonded to a hydroxyl group than when it exists as an oxide. Therefore, the power generation unit 102 of this embodiment can more effectively suppress an increase in Mn vapor pressure in the fuel chamber 176, thereby improving the performance of the unit cell 110.

In the power generation unit of this embodiment, at least a portion of the specific member 50 is housed in a groove 191 formed in the portion of the interconnector 190 that defines the non-reaction flow path section 176B. Therefore, with the power generation unit 102 of this embodiment, the specific member 50 can be positioned, and obstruction of the flow of fuel gas FG by the specific member 50 can be suppressed compared to a configuration in which the specific member 50 is not housed in the groove 191 of the interconnector 190.

In this embodiment, the power generation unit 102 includes multiple specific components 50, which are spaced apart from one another in a direction (Y-axis direction) intersecting the flow of fuel gas FG (gas flowing through the fuel chamber 176). Therefore, in the power generation unit 102 of this embodiment, compared to a configuration including only one specific component 50, the Mn contained in the interconnector 190 can be more effectively prevented from scattering into the fuel chamber 176. Furthermore, even though the power generation unit 102 includes multiple specific components 50, the multiple specific components 50 are spaced apart from one another in the above-mentioned direction (the direction (Y-axis direction) intersecting the flow of fuel gas FG), which relatively effectively prevents the specific components 50 from obstructing the flow of gas (fuel gas FG).

In the power generating unit of this embodiment, the interconnector 190 contains Cr. Therefore, in the power generating unit 102 of this embodiment, _Cr2O3 is formed on the surface of the interconnector 190. Furthermore, a compound of Mn and _Cr (such as (Cr, Mn) _3O4 ) with a low Mn vapor pressure is formed using the compound of Mn and Si formed on the surface of the interconnector 190 as a _nucleus , thereby further suppressing Mn from scattering into the fuel chamber 176. Therefore, according to the power generating unit 102 of this embodiment, it is possible to more effectively suppress an increase in Mn vapor pressure in the fuel chamber 176, thereby improving the performance of the single cell 110.

B. Second embodiment:
FIG. 11 is an explanatory diagram that schematically shows the configuration of a fuel cell module 10 according to the second embodiment.

The fuel cell module 10 can basically employ various conventional configurations, except that it includes a fuel cell stack 100A and a specific gas supply unit 200, which will be described later. In this embodiment, we will use as an example a fuel cell module 10 (see, for example, JP 2018-181405 A) that includes auxiliary devices such as an evaporator (evaporator 201, described later) that generates water vapor to be mixed with raw fuel gas RFG to generate fuel gas FG, and a combustor and reformer (neither of which are shown) that reform the raw fuel gas RFG. Below, we will basically only describe the configuration unique to the fuel cell module 10 of this embodiment, and will omit a description of other basic configurations.

As shown in FIG. 11, the fuel cell module 10 in this embodiment includes a fuel cell stack 100A and a specific gas supply unit 200. The fuel cell stack 100A is the fuel cell stack 100 of the first embodiment without the specific member 50. Note that a fuel cell stack 100 including the specific member 50 as in the first embodiment may be used instead of the fuel cell stack 100A.

The specific gas supply unit 200 supplies gas containing Si to the specific flow path unit 176A of the fuel chamber 176 of the fuel cell stack 100A. As described above, Si is a specific element that bonds with Mn contained in the interconnector 190. The specific gas supply unit 200 includes an evaporator 201, a raw fuel gas supply flow path 202, a water supply flow path 203, and a fuel gas supply flow path 204.

The evaporator 201 is a box-shaped member with an internal space, and is made of, for example, metal. The evaporator 201 is a device for evaporating water WA to generate water vapor. A member containing Si (hereinafter referred to as the "Si-containing member") 2011 (e.g., silica balls) is placed in the internal space of the evaporator 201.

The raw fuel gas supply flow path 202 is a flow path for supplying raw fuel gas RFG to the evaporator 201 to generate fuel gas FG, and is mainly composed of piping. The water supply flow path 203 is a flow path for supplying water WA to the evaporator 201, and is mainly composed of piping. The raw fuel gas supply flow path 202 and the water supply flow path 203 are each connected to the internal space of the evaporator 201. The fuel gas supply flow path 204 is a flow path for supplying fuel gas FG generated from raw fuel gas RFG (and water vapor) discharged from the evaporator 201 to the fuel cell stack 100A, and is mainly composed of piping. The fuel gas supply flow path 204 is connected to a gas passage member 27 of the fuel cell stack 100A (more precisely, a gas passage member 27 arranged at the position of the fuel gas supply manifold 171). The specific gas supply unit 200 described above is located outside the fuel cell stack 100A (and therefore outside the power generation unit 102), and can be said to be located upstream of the flow of gas (fuel gas FG) relative to the specific flow path unit 176A of the fuel chamber 176.

When water WA is supplied to the evaporator 201 via the water supply passage 203, the water WA is evaporated in the evaporator 201 to generate water vapor, which is then mixed with the raw fuel gas RFG. At this time, the specific element (Si) in the Si-containing member 2011 is dissolved by the water WA and dispersed as a gas. The raw fuel gas RFG mixed with the water vapor is then introduced, for example, from the evaporator 201 to a reformer (not shown) where it is steam reformed, resulting in the generation of a hydrogen-rich fuel gas FG. The generated fuel gas FG, still containing the specific element (Si), is supplied to the fuel gas supply manifold 171 of the fuel cell stack 100 via the gas passage member 27 (see Figures 3 and 6). The fuel gas FG supplied to the fuel gas supply manifold 171, still containing the specific element (Si), is then supplied to the fuel chamber 176 from the fuel gas supply manifold 171 via the fuel gas supply communication passage 142 of each power generation unit 102. The fuel gas FG supplied to the fuel chamber 176 is supplied to the non-reaction flow path section 176B of the fuel chamber 176 and ultimately to the specific flow path section 176A.

The fuel cell module 10 of this embodiment, by including the above-described specific gas supply unit 200, can achieve the same effects as those of the first embodiment. That is, the specific gas supply unit 200 supplies a gas (fuel gas FG) containing a specific element (Si) to the specific flow path portion 176A of the fuel chamber 176, which reacts with the Mn contained in the interconnector 190 to generate a compound of Mn and the specific element (Si) (e.g., Mn ₂ SiO ₄ (manganese silicate)). As a result, the Mn contained in the interconnector 190 is prevented from scattering into the fuel chamber 176. By positioning the specific gas supply unit 200 upstream of the flow of the gas (fuel gas FG) with respect to the specific flow path portion 176A, the compound of Mn and the specific element (Si) can be particularly efficiently generated on the surface of the interconnector 190, which is located downstream of the flow of the gas (fuel gas FG) with respect to the specific gas supply unit 200. Consequently, the Mn contained in the interconnector 190 is particularly effectively prevented from scattering into the fuel chamber 176. Therefore, according to the power generating unit 102 of this embodiment, compared to the above-mentioned conventional technology, the increase in Mn vapor pressure in the fuel chamber 176 can be particularly effectively suppressed, thereby improving the performance of the single cell 110.

C. Variations:
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 spirit thereof, for example, the following modifications are also possible.

The configurations of the fuel cell stacks 100, 100A and the components constituting the fuel cell stacks 100, 100A in the above embodiments are merely examples and can be modified in various ways. The configurations of the fuel cell module 10 and the components constituting the fuel cell module 10 in the above embodiments are also merely examples and can be modified in various ways. For example, in the first embodiment, the specific member 50 is rectangular, but the shape and size of the specific member 50 are not particularly limited and may be spherical, for example. Furthermore, the multiple specific members 50 provided in each power generation unit 102 are spaced apart from each other in the direction intersecting the flow of fuel gas FG (Y-axis direction), but the arrangement of each specific member 50 is not particularly limited. Furthermore, in the first embodiment, the power generation unit 102 includes multiple specific members 50, but it may include only one specific member 50.

In the above embodiment, the specific element (the element that bonds with Mn contained in the interconnector 190) of the specific member 50 and the specific gas supply unit 200 is Si, which is particularly suitable because it easily volatilizes when it comes into contact with water vapor. However, instead of or in addition to Si, an element other than Si (e.g., Ti (titanium), Al (aluminum), S (sulfur)) may be used as the specific element of the specific member 50 and the specific gas supply unit 200.

The specific gas supply unit 200 is not limited to the configuration described in the above embodiment and may have any configuration as long as it supplies a gas containing a specific element (an element that bonds with Mn contained in the interconnector 190) to the specific flow path portion 176A of the fuel chamber 176 of the fuel cell stack 100A. For example, in the above embodiment, the specific gas supply unit 200 may supply water WA containing a specific element (e.g., Si) via the water supply flow path 203. Also, in the above embodiment, the specific gas supply unit 200 may use a member containing the specific element Al (e.g., an alumina ball) instead of the Si-containing member 2011. Also, in the above embodiment, the specific gas supply unit 200 may use a pipe (or its inner surface) that constitutes any one of the raw fuel gas supply flow path 202, the water supply flow path 203, and the fuel gas supply flow path 204, which contains the specific element. Even in these configurations, the specific gas supply unit 200 can supply a gas containing the specific element to the specific flow path portion 176A of the fuel chamber 176 of the fuel cell stack 100A, thereby achieving the same effects as the above embodiment.

In the above embodiment, the specific gas supply unit 200 is located outside the fuel cell stack 100A (and therefore outside the power generation unit 102), but the specific gas supply unit 200 may be located within the fuel cell stack 100A, outside the power generation unit 102 within the fuel cell stack 100A, or within the power generation unit 102.

Furthermore, in the above embodiment, all of the power generating units 102 included in the fuel cell stacks 100, 100A are equipped with the specific member 50, but it is not necessary that all of the power generating units 102 included in the fuel cell stacks 100, 100A be equipped with the specific member 50; it is sufficient that at least one power generating unit 102 be equipped with the specific member 50.

Furthermore, in the above embodiment, the interconnector 190 includes a conductive coating layer 194, but the interconnector 190 may not include the coating layer 194. Further, in the above embodiment, the unit cell 110 includes a reaction prevention layer 118, but the unit cell 110 may not include the reaction prevention layer 118. Further, in the above embodiment, the number of unit cells 110 (the number of power generation units 102) included in the fuel cell stack 100 is merely an example, and the number of unit cells 110 is determined appropriately depending on the output voltage required for the fuel cell stack 100, etc. Further, the materials constituting each component in the above embodiment are merely examples, and each component may be made of other materials.

The interconnector 190 does not have to contain Cr.

The interconnector 190 may be configured such that each part (flat plate portion 150, air electrode side current collecting portion 134, IC separator 180) is partially or entirely made from a single member.

Furthermore, while the fuel cell stack 100 in the above embodiment is a counterflow type SOFC, the technology disclosed in this specification is equally applicable to coflow type SOFCs. Furthermore, the technology disclosed in this specification is equally applicable to crossflow type SOFCs.

The present invention may also be applied to a configuration including a metal-supported unit cell 110, as described in JP 2018-195414 A. This configuration also provides the same effects as the above embodiment.

In addition, while the above embodiment focuses on a fuel cell stack 100 that generates electricity using an electrochemical reaction between hydrogen contained in fuel gas and oxygen contained in oxidant gas, the technology disclosed in this specification can also be applied to an electrolysis cell stack that includes multiple electrolysis unit cells, which are constituent units of a solid oxide electrolysis cell (SOEC) that generates hydrogen using the electrolysis reaction of water. The basic configuration of an electrolysis cell stack is publicly known, as described in, for example, JP 2016-81813 A, and is roughly as follows: That is, the configuration of the electrolysis cell stack is the same as the configuration of the fuel cell stack 100 of the above-described embodiment, except that "power generation unit" is replaced with "electrolysis cell unit", "single cell" is replaced with "electrolysis single cell", "oxidant gas supply manifold" is replaced with "air discharge manifold", "oxidant gas discharge manifold" is replaced with "air supply manifold", "fuel gas supply manifold" is replaced with "hydrogen discharge manifold", "fuel gas discharge manifold" is replaced with "water vapor supply manifold", "oxidant gas supply communicating channel" is replaced with "air discharge communicating channel", "oxidant gas discharge communicating channel" is replaced with "air supply communicating channel", "fuel gas supply communicating channel" is replaced with "hydrogen discharge communicating channel", and "fuel gas discharge communicating channel" is replaced with "water vapor supply communicating channel".

During operation of the electrolysis cell stack, a voltage is applied to the electrolysis cell stack so that the air electrode 114 is positive (anode) and the fuel electrode (hydrogen electrode) 116 is negative (cathode). Steam is supplied as a raw material gas to the steam supply manifold via the gas passage member 27. The supplied steam may also contain hydrogen gas. The steam supplied to the steam supply manifold is then supplied to the fuel chamber 176 from the steam supply manifold via the steam supply communication channel of each electrolysis cell unit, and is used for the water electrolysis reaction in each electrolysis unit cell. The hydrogen gas generated in the fuel chamber 176 by the water electrolysis reaction in each electrolysis unit cell is discharged, along with any excess steam, via the hydrogen discharge communication channel to the hydrogen discharge manifold, and is then removed from the hydrogen discharge manifold via the gas passage member 27 to the outside of the electrolysis cell stack.

In addition, during operation of the electrolytic cell stack, air is supplied to the interior of the electrolytic cell stack as needed to control the temperature of the electrolytic cell stack, etc. In this case, air is supplied to the air supply manifold via the gas passage member 27, and then from the air supply manifold to the air chamber 166 via the air supply communication flow path of each electrolytic cell unit. The air supplied to the air chamber 166 is discharged to the air discharge manifold via the air discharge communication flow path together with oxygen generated at the air electrode 114, and then from the air discharge manifold to the outside of the electrolytic cell stack via the gas passage member 27.

By adopting a configuration similar to that of the fuel cell stack 100 in the above embodiment, an electrolysis cell stack with this configuration also achieves the same effects as those of the fuel cell stack 100 in the above embodiment.

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

10: Fuel cell module 22: Bolt 24: Nut 26: Insulating sheet 27: Gas passage member 28: Main body (of gas passage member) 29: Branch portion (of gas passage member) 32, 34: Hole 50: Specific member 100, 100A: Fuel cell stack 102: Power generation unit 103: Power generation block 104, 106: End plate 108: Communication hole 109: Bolt hole 110: Single cell 112: Electrolyte layer 114: Air electrode 116: Anode 118: Reaction prevention layer 120: Single cell separator 121: Through hole 124: Joint portion 125: Glass seal portion 126: Inner portion (of single cell separator) 127: Outer portion (of single cell separator) 128: Connection portion (of single cell separator) 130: Air electrode side frame 131: Hole 132: Oxidant gas supply communicating channel 133: Oxidant gas discharge communicating channel 134: Air electrode side current collecting portion (of interconnector) 140: Fuel electrode side frame 141: Hole 142: Fuel gas supply communicating channel 143: Fuel gas discharge communicating channel 144: Fuel electrode side current collector 145: Electrode side contact portion (of fuel electrode side current collector) 146: Opposite side contact portion (of fuel electrode side current collector) 147: Connection portion (of fuel electrode side current collector) 148: Y-direction tip portion 148A, 148B: X-direction tip portions 149: Spacer 150: Flat portion (of interconnector) 151: Joint portion 161: Oxidant gas supply manifold 162: Oxidant gas discharge manifold 166: Air chamber 171: Fuel gas supply manifold 172: Fuel gas discharge manifold 176: Fuel chamber 176A: Specific flow path portion (of fuel chamber) 176B: Non-reaction flow path portion (of fuel chamber) 180: IC separator (of interconnector) 181: Through hole 186: Inner portion (of IC separator) 187: Outer portion (of IC separator) 188: Connection portion (of IC separator) 189: Lower end separator 190: Interconnector 191: Groove portion 194: Coating layer (of interconnector) 196: Conductive bonding material 200: Specific gas supply portion 201: Evaporator 202: Raw fuel gas supply flow path 203: Water supply flow path 204: Fuel gas supply flow path 2011: Si-containing member FG: Fuel gas FOG: Fuel off-gas OG: Oxidant gas OOG: Oxidant off-gas RA: Reaction region RFG: Raw fuel gas UA: Non-reactive area WA: Water

Claims (5)

an electrochemical reaction unit cell including an electrolyte layer containing a solid oxide, and an air electrode and an anode facing each other in a first direction with the electrolyte layer sandwiched therebetween;
an interconnector located on the opposite side of the anode from the air electrode in the first direction, the interconnector defining a fuel chamber facing the anode and containing Mn;
The fuel chamber has a specific flow path portion located in a reaction region, which is a region where the electrolyte layer, the air electrode, and the fuel electrode overlap when viewed in the first direction, and a non-reaction flow path portion located in a non-reaction region not included in the reaction region, in the electrochemical reaction unit, further comprising:
a specific member that generates a gas containing a specific element that bonds with Mn contained in the interconnector, the specific member being located in the non-reaction flow path section on an upstream side of the flow of gas flowing in the fuel chamber with respect to the specific flow path section, and at least a portion of the specific member facing the fuel chamber;
the specific element is any one of Ti, Al, and S,
The content of the specific element in the specific component is 10% by mass or more,
At least a part of the specific member is accommodated in a groove formed in a portion of the interconnector that defines the non-reaction channel section.
An electrochemical reaction unit characterized by: an electrochemical reaction unit cell including an electrolyte layer containing a solid oxide, and an air electrode and an anode facing each other in a first direction with the electrolyte layer sandwiched therebetween;
an interconnector located on the opposite side of the anode from the air electrode in the first direction, the interconnector defining a fuel chamber facing the anode and containing Mn;
The fuel chamber has a specific flow path portion located in a reaction region, which is a region where the electrolyte layer, the air electrode, and the fuel electrode overlap when viewed in the first direction, and a non-reaction flow path portion located in a non-reaction region not included in the reaction region, in the electrochemical reaction unit, further comprising:
a specific member that generates a gas containing a specific element that bonds with Mn contained in the interconnector, the specific member being located in the non-reaction flow path section on an upstream side of the flow of gas flowing in the fuel chamber with respect to the specific flow path section, and at least a portion of the specific member facing the fuel chamber;
the specific element is any one of Ti, Al, and S,
The content of the specific element in the specific component is 10% by mass or more,
The electrochemical reaction unit includes a plurality of the specific members,
The plurality of specific members are spaced apart from one another in a direction intersecting the flow of gas flowing through the fuel chamber.
An electrochemical reaction unit characterized by: 3. The electrochemical reaction unit according to claim 1 or 2 ,
The specific component has the specific element bonded to a hydroxyl group.
An electrochemical reaction unit characterized by: The electrochemical reaction unit according to any one of claims 1 to 3 ,
The interconnector includes Cr.
An electrochemical reaction unit characterized by: an electrochemical reaction unit cell including an electrolyte layer containing a solid oxide, and an air electrode and an anode facing each other in a first direction with the electrolyte layer sandwiched therebetween;
an interconnector located on the opposite side of the anode from the air electrode in the first direction, the interconnector defining a fuel chamber facing the anode and containing Mn;
An electrochemical reaction module having an electrochemical reaction unit comprising:
When a portion of the fuel chamber that is located in a reaction region where the electrolyte layer, the air electrode, and the fuel electrode overlap when viewed in the first direction is defined as a specific flow path portion,
a specific gas supply unit that is located outside the electrochemical reaction unit and upstream of the specific flow path unit in the gas flow that flows through the fuel chamber, and that supplies a gas containing Si, which is a specific element, to the specific flow path unit;
Electrochemical reaction module characterized by: