Electrochemical Reaction Unit and Electrochemical Reaction Module

Abstract

To inhibit the scattering of Mn contained in an interconnector into a fuel chamber.SOLUTION: An electrochemical reaction unit includes: an electrochemical reaction single cell that includes an electrolyte layer containing a solid oxide, and an air electrode and a fuel electrode facing each other in a first direction with the electrolyte layer sandwiched therebetween; and a Mn-containing interconnector that is located on the opposite side of the air electrode in the first direction with respect to the fuel electrode and that defines a fuel chamber facing the fuel electrode. The fuel chamber has: a specific passage part located in a reaction area that is an area where the electrolyte layer, the air electrode and the fuel electrode are overlapped in a first directional view; and a non-reaction passage part located in a non-reaction area that is not included in the reaction area. The electrochemical reaction unit further includes a specific member that contains Si of a specific element and that is located on the upstream side of a flow of gas flowing in the fuel chamber with respect to the specific passage part in the non-reaction passage part, the specific member at least partially facing the fuel chamber.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The technology disclosed herein relates to an electrochemical reaction unit and an electrochemical reaction module. [Background technology]

[0002] Solid oxide fuel cells (hereinafter referred to as "SOFCs") are known as one type of fuel cell that generates electricity using an electrochemical reaction between hydrogen and oxygen. A fuel cell power generation unit (hereinafter referred to as "power generation unit"), which is a constituent unit of an SOFC, includes a fuel cell unit cell (hereinafter referred to as "unit cell") and an interconnector (see, for example, Patent Document 1). The unit cell includes an electrolyte layer containing a solid oxide, and an air electrode and an anode that face each other in a predetermined direction (hereinafter referred to as "first direction") with the electrolyte layer in between. The interconnector is located on the opposite side of the anode from the air electrode in the first direction. The interconnector defines (part of) a fuel chamber that faces the anode. The interconnector is made of ferritic stainless steel. Therefore, the interconnector contains Mn. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2021-086786 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-described conventional configuration, Mn contained in the interconnector is dispersed into the fuel chamber, which increases the Mn vapor pressure in the fuel chamber and may cause cracks in the electrolyte layer, adversely affecting the performance of the electrochemical reaction unit cell.

[0005] Such 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, a fuel cell unit and an electrolysis cell are collectively referred to as an electrochemical reaction unit, and a fuel cell power generation unit and an electrolysis cell unit are collectively referred to as an electrochemical reaction unit. Such issues are not limited to SOFCs and SOECs, but are also common to other types of electrochemical reaction units. Such issues are also common to electrochemical reaction modules that include electrochemical reaction units and have gas flow paths located inside and outside the electrochemical reaction units.

[0006] This specification discloses a technique that can solve the above-mentioned problems. [Means for solving the problem]

[0007] The technology disclosed in this specification can be realized, for example, in the following forms.

[0008] (1) 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 with the electrolyte layer sandwiched therebetween, and an interconnector located on the opposite side of the anode in the first direction from the air electrode, 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.

[0009] In this electrochemical reaction unit, since the specific component described above is provided, the specific element contained in the specific component 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 component 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 component. This in turn makes it particularly effective to prevent the Mn contained in the interconnector from dispersing into the fuel chamber. Therefore, according to 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 unit cell.

[0010] (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 with the electrolyte layer sandwiched therebetween, and an interconnector located on the opposite side of the anode in the first direction from the air electrode, 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 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 portion upstream of the flow of gas flowing in the fuel chamber with respect to the specific flow path portion and at least a portion of which faces the fuel chamber. For the same reasons as above, the electrochemical reaction unit of this invention, which includes a specific component, can more effectively suppress the increase in Mn vapor pressure in the fuel chamber than the conventional technology described above, thereby improving the performance of the single cell.

[0011] In this electrochemical reaction unit, since the specific component described above is provided, the specific element contained in the specific component 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 component is located upstream of the gas flow relative to the specific flow path section of the fuel chamber, so that the compound of Mn and the specific element described above can be particularly efficiently formed on the surface of the interconnector located downstream of the gas flow relative to the specific flow path section. This in turn particularly effectively prevents the Mn contained in the interconnector from dispersing into the fuel chamber. Therefore, according to 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 unit cell.

[0012] (3) In the electrochemical reaction unit, the content of the specific element in the specific component may be 10% by 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.

[0013] (4) In the 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.

[0014] (5) In the electrochemical reaction unit, at least a part of the specific member may be accommodated in a groove formed in a portion of the interconnector that defines the non-reaction flow path section. 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 the groove of the interconnector.

[0015] (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. This electrochemical reaction unit can more effectively prevent Mn contained in the interconnector from scattering into the fuel chamber compared to a configuration including only one specific component. 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 can relatively effectively prevent the specific components from obstructing the flow of gas.

[0016] (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.

[0017] (8) The electrochemical reaction module disclosed in the present specification has 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 with the electrolyte layer sandwiched therebetween, and an interconnector located on the opposite side of the anode in the first direction from the air electrode, the interconnector 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 that includes the fuel chamber; a second flow path portion that is a gas flow path located outside the electrochemical reaction unit and that 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 that is located in a reaction region where the electrolyte layer, the air electrode, and the fuel electrode 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 that is located upstream of the specific flow path portion in at least one of the first flow path portion and the second flow path portion and 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 Mn contained in the interconnector from scattering into the fuel chamber. By positioning the specific gas supply unit upstream of the specific flow path unit in the gas flow direction, the compound of Mn and the specific element described above can be particularly efficiently generated on the surface of the interconnector located downstream of the specific gas supply unit in the gas flow direction, and as a result, the Mn contained in the interconnector is particularly effectively prevented from scattering into the fuel chamber. Therefore, according to this electrochemical reaction module, an increase in Mn vapor pressure in the fuel chamber can be particularly effectively prevented compared to the above-mentioned conventional technology, thereby improving the performance of the single cell.

[0018] The technology disclosed in this specification can be realized in various forms, for example, in the form of an electrochemical reaction unit (fuel cell power generation unit or electrolysis cell unit), a manufacturing method thereof, etc. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a perspective view showing the external configuration of a fuel cell stack 100 according to a first embodiment; [Figure 2] 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. [Figure 3] 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. [Figure 4] FIG. 4 is an explanatory diagram showing the YZ cross-sectional configuration of the fuel cell stack 100 taken along the line IV-IV in FIG. 1. [Figure 5] 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. [Figure 6] 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. [Figure 7] 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. 4. [Figure 8] 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. [Figure 9] 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. [Figure 10] FIG. 8 is an explanatory diagram showing the XY cross-sectional configuration of the power generating unit 102 at the position XX in FIGS. 5 to 7. [Figure 11] FIG. 10 is an explanatory diagram illustrating a schematic configuration of a fuel cell module 10 according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0020] 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 in the first embodiment. FIG. 2 is an explanatory diagram showing the 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 the 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 the 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 will be referred to 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.

[0021] 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-end separator 189, and a pair of end plates 104, 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, 106 (hereinafter referred to as the "upper end plate 104") is arranged above an 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-end separator 189. The pair of end plates 104, 106 are arranged to sandwich the power generation block 103 from above and below. The arrangement direction (Z-axis direction, vertical direction) is an example of a first direction in the claims.

[0022] 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 the outer periphery around the Z axis. Corresponding holes formed in these layers communicate with each other in the vertical direction 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 the bolt holes 109 may also be referred to as bolt holes 109.

[0023] A bolt 22 is inserted into each bolt hole 109. The lower end of each bolt 22 is threaded 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 manner fasten the layers of the fuel cell stack 100 together. The insulating sheet 26 is made of, for example, a mica sheet, a ceramic fiber sheet, a pressed ceramic powder sheet, a glass sheet, a glass ceramic composite, or the like.

[0024] 1 to 3, four holes that vertically penetrate each layer are formed in the peripheral portion around the Z axis direction of each layer (each power generating 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 generating 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.

[0025] 1 and 2, one communication hole 108 located near one side (the side on the positive X-axis side of 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 that introduces an oxidant gas OG from outside the fuel cell stack 100 and supplies the oxidant gas OG to an air chamber 166 (described later) of each power generating unit 102, and one communication hole 108 located near the side opposite to the first side (the side on the negative X-axis side of two sides parallel to the Y-axis) functions as an oxidant gas discharge manifold 162, which is a gas flow path that discharges an oxidant off-gas OOG, which is a gas discharged from the air chamber 166 of each power generating unit 102, to the outside of the fuel cell stack 100. Note that, for example, air is used as the oxidant gas OG.

[0026] 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 discharge 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 fuel chambers 176 (described later) of each power generating unit 102, and another 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 discharge manifold 172, which is a gas flow path through which fuel off-gas FOG, which is gas discharged from the fuel chambers 176 of each power generating unit 102, is discharged to the outside of the fuel cell stack 100. Note that, for example, hydrogen-rich gas obtained by reforming city gas is used as the fuel gas FG.

[0027] 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 surface of the main body 28. The holes of the branch portion 29 are in communication with the holes of 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 of the main body 28 of the gas passage member 27 arranged at the position of the oxidant gas supply manifold 161 is in communication with the oxidant gas supply manifold 161, and the hole of the main body 28 of the gas passage member 27 arranged at the position of the oxidant gas discharge manifold 162 is in communication with the oxidant gas discharge manifold 162. 3, the holes in main body 28 of gas passage member 27 arranged at the position of fuel gas supply manifold 171 communicate with fuel gas supply manifold 171, and the holes in main body 28 of gas passage member 27 arranged at the position of fuel gas discharge manifold 172 communicate with fuel gas discharge manifold 172. Note that insulating sheet 26 is interposed between each gas passage member 27 and the surface of lower end plate 106.

[0028] (Configuration of end plates 104 and 106) The pair of end plates 104, 106 are flat, plate-shaped members with 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, 34 are formed near the centers of the pair of end plates 104, 106, respectively, penetrating in the Z-axis direction. When 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, which will be 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, which will be 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.

[0029] (Configuration of the lower 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.

[0030] (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 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 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 position XX in Figs. 5 to 7.

[0031] 5 to 7, the power generating 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 uppermost and lowermost layers of the power generating 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 in the peripheral portions around the Z axis 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, which will be described later).

[0032] 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 therebetween, and a reaction prevention layer 118 that is disposed between the electrolyte layer 112 and the air electrode 114. 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).

[0033] 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 fuel electrode 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 air electrode 114 from reacting with elements (e.g., Zr) contained in the electrolyte layer 112 to produce a highly resistive substance (e.g., SrZrO3).

[0034] The single cell separator 120 is a frame-shaped conductive member having a substantially rectangular through-hole 121 formed near the center in the vertical direction, and is made of, for example, metal. The plate thickness of the single cell separator 120 is relatively thin, for example, about 0.05 mm or more and 0.2 mm or less. A 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 of a brazing material (e.g., Ag brazing) placed in the facing portion. Therefore, it can be said that the single cell separator 120 is 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 suppressing gas leakage (cross leakage) from one electrode side to the other electrode side at the periphery of the single cell 110.

[0035] The single cell separator 120 includes an inner portion 126 including the through-hole periphery of the single cell separator 120, an outer portion 127 located outside the inner portion 126, and a connecting portion 128 connecting the inner portion 126 and the outer portion 127. In this embodiment, the inner portion 126 and the outer portion 127 are generally flat plate-shaped extending in a direction generally perpendicular to the Z-axis direction. The connecting portion 128 has a curved shape so as to protrude downward relative to both the inner portion 126 and the outer portion 127. A lower portion of the connecting portion 128 (on the fuel chamber 176 side) is a convex portion, and an upper portion of the connecting portion 128 (on the air chamber 166 side) is a concave portion. Therefore, the connecting portion 128 includes a portion whose position in the Z-axis direction differs from that of the inner portion 126 and the outer portion 127.

[0036] A glass seal portion 125 containing glass is disposed near the through-hole 121 in the unit 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 be in contact with both the surface of the unit cell separator 120 around the through-hole and the surface of the unit 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 unit cell 110.

[0037] The interconnector 190 is a conductive member having a substantially rectangular flat plate portion 150, a plurality of substantially columnar air electrode side current collecting portions 134 protruding from the flat plate portion 150 toward the air electrode 114 side, and an IC separator 180, and is formed of a metal (e.g., ferritic stainless steel) containing Mn (manganese) and Cr (chromium). The interconnector 190 defines (a part of) the fuel chamber 176 facing the anode 116. In this embodiment, a conductive coating layer 194 made of, for example, a spinel-type oxide is formed on the surfaces (surfaces facing the air chamber 166) of the flat plate portion 150 and the air electrode side current collecting portion 134 of the interconnector 190. Hereinafter, the interconnector 190 on which the coating layer 194 is formed 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 disposed above the single cell 110. The upper interconnector 190 (each of the air electrode-side current collectors 134) is bonded 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 generating unit 102, the lower interconnector 190 is disposed below the unit cell 110 with the fuel chamber 176 interposed therebetween, and is electrically connected to the anode 116 of the unit cell 110 via an anode-side current collector 144, which will be described later. The interconnector 190 ensures electrical conduction between the power generating units 102 and also suppresses mixing of reactant gases between the power generating units 102. In this embodiment, when two power generating units 102 are disposed adjacent to each other, one interconnector 190 is shared by the two adjacent power generating units 102. That is, the upper interconnector 190 of a certain power generating unit 102 is 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 is provided with a lower-end separator 189, the power generating unit 102 located at the bottom of the fuel cell stack 100 does not have a lower interconnector 190 (see Figures 2 to 4).

[0038] The IC separator 180 is a frame-shaped member having a substantially rectangular through-hole 181 formed near the center in the vertical direction, and is made of, for example, metal. The plate thickness of the IC separator 180 is relatively thin, for example, about 0.05 mm or more and 0.2 mm or less. The IC separator 180 faces the unit cell separator 120 in the Z-axis direction. A 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 the 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 manner, 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 uppermost position in the fuel cell stack 100 is electrically connected to the upper end plate 104.

[0039] The IC separator 180 includes an inner portion 186 including a 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 plate-shaped extending in a direction generally perpendicular to the Z-axis direction. The connecting portion 188 has a curved shape 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 (on the air chamber 166 side) is a convex portion, and the upper portion of the connecting portion 188 (on the fuel chamber 176 side) 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.

[0040] As shown in FIGS. 5 to 8 , the air electrode side frame 130 is a frame-shaped member with a substantially rectangular hole 131 formed near the center and penetrating in the Z-axis direction, and is formed of an insulator such as mica. The hole 131 in the air electrode side frame 130 forms (a 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 them (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 included in the power generating unit 102 (i.e., between a pair of interconnectors 190). In addition, the air electrode side frame 130 is formed with an oxidant gas supply communication passage 132 that connects the oxidant gas supply manifold 161 and the air chamber 166, and an oxidant gas discharge communication passage 133 that connects the air chamber 166 and the oxidant gas discharge manifold 162.

[0041] 5 to 7, 9, and 10, the fuel electrode side frame 140 is a frame-shaped member having 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.

[0042] 10, the fuel chamber 176 has a specific flow path portion 176A located in a region RA where the electrolyte layer 112, the air electrode 114, and the 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 a region UA ​​not included in the reaction region RA (hereinafter referred to as the "non-reaction region"). The reaction region RA is a region where the power generation reaction mainly occurs and has a relatively large contribution to power generation, whereas 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 at the center of the unit cell 110, and the non-reaction region UA ​​is located so as to surround the periphery of the reaction region RA.

[0043] In addition, the fuel electrode side frame 140 is formed with a fuel gas supply communication channel 142 that connects the fuel gas supply manifold 171 and the fuel chamber 176, and a fuel gas discharge communication channel 143 that connects the fuel chamber 176 and the fuel gas discharge manifold 172.

[0044] 5 to 7, the fuel electrode side current collector 144 is disposed in the fuel chamber 176. The fuel electrode side current collector 144 is located between the unit cell 110 and the interconnector 190.

[0045] 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 to the fuel electrode 116. The opposite side contact portion 146 contacts an 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 this 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 fuel electrode-side current collector 144 has such a configuration, and electrically connects the fuel electrode 116 to the interconnector 190 (or the bottom-end separator 189). A rod-shaped spacer 149 made of, for example, mica is disposed between the electrode-side contact portion 145 and the bottom-end contact portion 146 of the fuel electrode-side current collector 144. This allows the fuel electrode-side current collector 144 to follow deformation of the power generating unit 102 due to temperature cycles and fluctuations in reactant gas pressure, and maintains good electrical connection between the fuel electrode 116 and the interconnector 190 (or the bottom-end separator 189) via the fuel electrode-side current collector 144. 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.

[0046] Each power generating unit 102 has a plurality of 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 the Y-direction tip 148 of the fuel electrode side current collector 144 to the interconnector 190 (for example, by spot welding using a laser).

[0047] 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 and 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 and 148B. This prevents the spacer 149 from shifting position.

[0048] In this embodiment, the opposite side contact portion 146, the electrode side contact portion 145, the connecting portion 147, the Y-direction tip portion 148, the X-direction tip portion 148A, and the X-direction tip portion 148B of the fuel electrode side current collector 144 are formed as an integrated member.

[0049] In this embodiment, the fuel electrode side current collector 144 is formed from a metal foil (e.g., 10 to 800 μm thick) 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 fuel cell stack 100: 2 and 5, when oxidant gas OG is supplied through a gas pipe (not shown) connected to branch portion 29 of gas passage member 27 provided at the position of oxidant gas supply manifold 161, the oxidant gas OG is supplied to oxidant gas supply manifold 161 through branch portion 29 of gas passage member 27 and holes in main body 28, and then supplied from oxidant gas supply manifold 161 to air chamber 166 through oxidant gas supply communicating passages 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 branch portion 29 of gas passage member 27 provided at the position of fuel gas supply manifold 171, the fuel gas FG is supplied to fuel gas supply manifold 171 through branch portion 29 of gas passage member 27 and holes in main body 28, and then supplied from fuel gas supply manifold 171 to fuel chamber 176 through fuel gas supply communicating passages 142 of each power generating unit 102.

[0050] When an oxidant gas OG is supplied to the air chamber 166 of each power generating unit 102 and a fuel gas FG is supplied to the fuel chamber 176, power is generated in the unit cell 110 by an electrochemical reaction between the oxidant gas OG and the fuel gas FG. This power generation reaction is exothermic. In each power generating unit 102, the air electrode 114 of the unit cell 110 is electrically connected to an upper interconnector 190, and the anode 116 is electrically connected to a lower interconnector 190 (or a lower-end separator 189) via an anode-side current collector 144. That is, the multiple power generating units 102 included in the fuel cell stack 100 are electrically connected in series. The upper interconnector 190 of the uppermost power generating unit 102 is electrically connected to the upper end plate 104, and the lower-end separator 189 electrically connected to the anode-side current collector 144 of the lowermost power generating unit 102 is electrically connected to the lower end plate 106. Therefore, the electrical energy generated in each power generating unit 102 is extracted from the end plates 104, 106 which function as output terminals of the fuel cell stack 100. Since SOFCs generate electricity at relatively high temperatures (e.g., 700°C to 1000°C), the fuel cell stack 100 may be heated by a heater (not shown) after startup until the high temperature can be maintained using the heat generated by power generation.

[0051] 2 and 5, the oxidant off-gas OOG discharged from the air chamber 166 of each power generating unit 102 through the oxidant gas discharge communicating passage 133 to the oxidant gas discharge manifold 162 passes through holes in the main body 28 and branch portion 29 of the gas passage member 27 provided at the position of the oxidant gas discharge manifold 162, and is then discharged to the outside of the fuel cell stack 100 through 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 through the fuel gas discharge communicating passage 143 to the fuel gas discharge manifold 172 passes through holes in the main body 28 and branch portion 29 of the gas passage member 27 provided at the position of the fuel gas discharge manifold 172, and is then discharged to the outside of the fuel cell stack 100 through a gas pipe (not shown) connected to the branch portion 29.

[0052] 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 communicating passage 132 communicating with the oxidant gas supply manifold 161 and the fuel gas discharge communicating passage 143 communicating with the fuel gas discharge manifold 172 are arranged to face (in the same direction) one side of the single cell (the second side SI2 shown in Figures 8 and 10), and the oxidant gas discharge communicating passage 133 communicating with the oxidant gas discharge manifold 162 and the fuel gas supply communicating 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 single cell across the center point of the single 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 the oxidant gas OG in the air chamber 166 (direction from the positive direction of the X-axis to the negative direction of the X-axis) and the main flow direction of the fuel gas FG in the fuel chamber 176 (direction from the negative direction of the X-axis to the positive direction of the X-axis) are approximately opposite directions (opposing each other).

[0053] 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.

[0054] The specific member 50 is a rectangular parallelepiped member (for example, mica) containing Si (silicon). Si corresponds to an element (hereinafter referred to as "specific element") that bonds with Mn contained in the interconnector 190. Note that mica contains Si bonded to a hydroxyl group (OH). Furthermore, the presence of the specific element (Si) bonded to a hydroxyl group (OH) in the specific member 50 can be confirmed by a method of identifying a crystalline phase by X-ray diffraction (XRD) or by a method of identifying a hydroxyl group bond peak (for example, in the case of a Si-OH bond, a peak in the range of 3600 to 3800 cm) by Fourier transform infrared spectroscopy (FT-IR). -1 This can be confirmed by detecting the peak.

[0055] At least a portion of each specific member 50 faces the fuel chamber 176. Therefore, during operation of the fuel cell stack 100, the specific element (Si) contained in the specific member 50 is dispersed as a gas into the fuel chamber 176. Therefore, the specific member 50 corresponds to a member that generates a gas containing the specific element (Si).

[0056] 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 of each specific member 50 in the X-axis direction or Y-axis direction is, for example, 1 mm or more and 500 mm or less.

[0057] The content of the specific element (Si) in each specific component 50 is 10 mass % or more (for example, 21 mass % in the case of muscovite). The content of the specific element (Si) in the specific component 50 can be measured by performing ICP emission spectrometry on a sample obtained by dissolving the specific component 50 using nitric acid or the like.

[0058] 5 and 6, the specific member 50 is placed on an IC separator 180 of the interconnector 190 that 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 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 191 of the interconnector 190. Note that, although the entire specific member 50 may be accommodated in the groove 191 of the interconnector 190 as shown in FIGS. 5 and 6, only a portion of the specific member 50 may be accommodated in the groove 191 of the interconnector 190.

[0059] As shown in FIG. 10, the plurality of (six) specific members 50 provided in each power generating unit 102 are located in the non-reaction channel section 176B of the fuel chamber 176 on the upstream side of the flow of the fuel gas FG relative to the specific channel section 176A.

[0060] The multiple (six) specific members 50 provided in each power generating unit 102 are spaced apart from one another in a direction (Y-axis direction) intersecting 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) intersecting the flow of fuel gas FG, or may be arranged in a non-linear manner (for example, a curved line) so as to be spaced apart from one another in the direction (Y-axis direction) intersecting the flow of fuel gas FG.

[0061] 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 an air electrode 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 air electrode 114 in the Z-axis direction. The interconnector 190 defines a fuel chamber 176 that faces 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 air electrode 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 component 50 that contains 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.

[0062] In the power generating unit 102 of this embodiment, since the power generating unit 102 includes the above-mentioned specific component 50, the specific element (Si) contained in the specific component 50 scatters as a gas into the fuel chamber 176 and reacts with the Mn contained in the interconnector 190 to generate a compound of Mn and the specific element (Si) (such as Mn2SiO4 (manganese silicate)). As a result, the Mn contained in the interconnector 190 is prevented from scattering into the fuel chamber 176. This is because the 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 component 50 is located upstream of the flow of the gas (fuel gas FG) with respect to the specific flow path section 176A of the fuel chamber 176. This makes it possible to particularly efficiently generate the above-mentioned compound of Mn and the specific element (Si) 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 component 50. 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, the increase in Mn vapor pressure in the fuel chamber 176 can be suppressed particularly effectively compared to the above-mentioned conventional technology, thereby improving the performance of the single cell 110.

[0063] In the power generating unit of this embodiment, the content of the specific element (Si) in the specific member 50 is 10 mass % or more. Therefore, according to 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.

[0064] 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 is present 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.

[0065] In the power generation unit of this embodiment, at least a portion of the specific member 50 is accommodated in a groove 191 formed in a portion of the interconnector 190 that defines the non-reaction flow path section 176B. Therefore, according to the power generation unit 102 of this embodiment, the specific member 50 can be positioned, and compared to a configuration in which the specific member 50 is not accommodated in the groove 191 of the interconnector 190, obstruction of the flow of the fuel gas FG by the specific member 50 can be suppressed.

[0066] In this embodiment, the power generating unit 102 includes a plurality of specific components 50, and the multiple specific components 50 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 generating unit 102 of this embodiment, compared to a configuration including only one specific component 50, it is possible to more effectively prevent Mn contained in the interconnector 190 from scattering into the fuel chamber 176. Furthermore, even though the power generating unit 102 includes a plurality of specific components 50, because the multiple specific components 50 are spaced apart from one another in the above direction (the direction (Y-axis direction) intersecting the flow of fuel gas FG), it is possible to relatively prevent the specific components 50 from obstructing the flow of gas (fuel gas FG).

[0067] 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, which further suppresses 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 unit cell 110.

[0068] 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.

[0069] 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, a fuel cell module 10 (see, for example, JP 2018-181405 A) will be described as an example, which includes auxiliary devices such as an evaporator (evaporator 201, which will be 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, only the configuration unique to the fuel cell module 10 of this embodiment will be described, and a description of other basic configurations will be omitted.

[0070] 11, the fuel cell module 10 of 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 the fuel cell stack 100 including the specific member 50 as in the first embodiment may be used instead of the fuel cell stack 100A.

[0071] The specific gas supply unit 200 is a part that 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 corresponds to the specific element that is an 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.

[0072] 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 "Si-containing member") 2011 (for example, silica balls) is arranged in the internal space of the evaporator 201.

[0073] The raw fuel gas supply flow path 202 is a flow path for supplying raw fuel gas RFG to the evaporator 201 for generating 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 above-mentioned specific gas supply section 200 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 section 176A of the fuel chamber 176.

[0074] When water WA is supplied to the evaporator 201 through 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 introduced, for example, from the evaporator 201 to a reformer (not shown) and steam-reformed in the reformer, thereby generating a hydrogen-rich fuel gas FG. The generated fuel gas FG, 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 FIGS. 3 and 6). The fuel gas FG supplied to the fuel gas supply manifold 171, 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 channel section 176B of the fuel chamber 176, and further to the specific channel section 176A.

[0075] The fuel cell module 10 of this embodiment, by including the above-described specific gas supply unit 200, can obtain 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 section 176A of the fuel chamber 176, which reacts with Mn contained in the interconnector 190 to generate a compound of Mn and the specific element (Si) (e.g., MnSiO (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 section 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, the increase in Mn vapor pressure in the fuel chamber 176 can be suppressed particularly effectively compared to the above-mentioned conventional technology, thereby improving the performance of the single cell 110.

[0076] C. Variations: The technology disclosed in this specification is not limited to the above-described embodiments, and can be modified into various forms without departing from the spirit thereof, for example, the following modifications are also possible.

[0077] 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 has a rectangular parallelepiped shape, 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 included in each power generation unit 102 are spaced apart from each other in the direction intersecting the flow of the fuel gas FG (Y-axis direction), but the arrangement of the specific members 50 is not particularly limited. Furthermore, in the first embodiment, the power generation unit 102 includes multiple specific members 50, but may include only one specific member 50.

[0078] 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 (for example, Ti (titanium), Al (aluminum), or S (sulfur)) may be used as the specific element of the specific member 50 or the specific gas supply unit 200.

[0079] 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. In addition, in the above embodiment, the specific gas supply unit 200 may use a member containing Al, which is the specific element, (e.g., an alumina ball) instead of the Si-containing member 2011. In addition, in the above embodiment, the specific gas supply unit 200 may use a pipe (inner surface) constituting 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. In these configurations, the specific gas supply unit 200 may 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 those of the above embodiment.

[0080] 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, may be located outside the power generation unit 102 within the fuel cell stack 100A, or may be located within the power generation unit 102.

[0081] Furthermore, in the above embodiment, all of the power generation 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 generation units 102 included in the fuel cell stacks 100, 100A are equipped with the specific member 50; it is sufficient that at least one of the power generation units 102 is equipped with the specific member 50.

[0082] 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. Furthermore, in the above embodiment, the unit cell 110 has a reaction prevention layer 118, but the unit cell 110 may not have a reaction prevention layer 118. Furthermore, 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. Furthermore, the materials constituting each component in the above embodiment are merely examples, and each component may be made of other materials.

[0083] The interconnector 190 may not contain Cr.

[0084] The interconnector 190 may be configured such that each of the parts (the flat plate part 150, the air electrode side current collecting part 134, and the IC separator 180) is partly or entirely made of a single member.

[0085] Although the fuel cell stack 100 of the above embodiment is a counterflow type SOFC, the technology disclosed in this specification is equally applicable to coflow type SOFCs and crossflow type SOFCs.

[0086] The present invention may also be applied to a configuration including a metal-supported unit cell 110, as described in JP 2018-195414 A. In this configuration, the same effects as those of the above embodiment can be obtained.

[0087] Furthermore, while the above embodiment is directed to a fuel cell stack 100 that generates electricity by utilizing an electrochemical reaction between hydrogen contained in a fuel gas and oxygen contained in an oxidant gas, the technology disclosed in this specification is similarly applicable 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 by utilizing 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 "steam 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 "steam supply communicating channel".

[0088] 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 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, together with excess steam, via the hydrogen discharge communication channel to the hydrogen discharge manifold, and is then taken out of the electrolysis cell stack from the hydrogen discharge manifold via the gas passage member 27.

[0089] During operation of the electrolytic cell stack, air is supplied to the interior of the electrolytic cell stack as needed, for example to control the temperature of the electrolytic cell stack. In this case, air is supplied to the air supply manifold via the gas passage member 27, and then supplied from the air supply manifold to the air chamber 166 via the air supply communicating flow path of each electrolytic cell unit. The air supplied to the air chamber 166 is discharged together with oxygen generated at the air electrode 114 via the air discharge communicating flow path to the air discharge manifold, and then from the air discharge manifold to the outside of the electrolytic cell stack via the gas passage member 27.

[0090] In an electrolysis cell stack having such a configuration, by adopting the same configuration as 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 achieved.

[0091] Furthermore, although 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). [Explanation of symbols]

[0092] 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: fuel electrode 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: connecting 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 path 203: Water supply path 204: Fuel gas supply 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-reaction region WA: Water

Claims

1. 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 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:

2. An electrochemical reaction unit cell including an electrolyte layer including a solid oxide, and an air electrode and a fuel electrode 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 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. 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:

4. The electrochemical reaction unit according to any one of claims 1 to 3, The interconnector includes Cr. An electrochemical reaction unit characterized by:

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; 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; An electrochemical reaction module characterized by:

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