JP7507738B2 - Electrochemical reaction unit and electrochemical reaction cell stack - Google Patents

Description

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

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 the constituent unit of an SOFC, has a single fuel cell cell (hereinafter referred to as "single cell"). The single cell includes an electrolyte layer containing solid oxide, and an air electrode and a fuel electrode that face each other in a specific direction (hereinafter referred to as "first direction") across the electrolyte layer.

The power generation unit also has a single cell separator and an interconnector. The single cell separator is a conductive member that is joined to the single cell and separates a gas chamber facing the air electrode from a gas chamber facing the fuel electrode. The interconnector is a conductive member that is disposed to face one of the fuel electrode and the air electrode (hereinafter referred to as the "specific electrode") in the first direction and is electrically connected to the specific electrode.

The interconnector has a corner in a cross section along the first direction. The corner of the interconnector is a portion that is substantially perpendicular to the first direction in the cross section and connects a surface that at least a portion of which faces the specific electrode with a surface facing the outer periphery. The corner of the interconnector exists, for example, on the outer periphery of the interconnector. Furthermore, if there is a step on the surface of the interconnector that faces the specific electrode, the outer periphery of the interconnector also exists on the outer periphery of the step. Conventionally, the corner of an interconnector has a portion that is bent at an angle of 90 degrees (or less) (see, for example, Patent Document 1).

JP 2021-22460 A

In the power generation unit, deformation such as warping occurs in each component due to changes in temperature and gas pressure, and as a result, the distance between the corner of the interconnector and the single cell separator may become smaller. As described above, in conventional power generation units, the corner of the interconnector has a portion that is bent at an angle of 90 degrees (or less), and an electric field is likely to concentrate in this portion. Therefore, if the distance between the corner of the interconnector and the single cell separator becomes small, there is a risk of a short circuit occurring between the two. If such a short circuit occurs, there is a risk of the single cell being damaged.

Note that these issues are also common to electrolysis cell units, including electrolysis unit cells, which are constituent units of solid oxide electrolysis cells (hereinafter referred to as "SOECs") that generate hydrogen using the electrolysis reaction of water. Note that in this specification, a fuel cell unit cell and an electrolysis unit cell are collectively referred to as an electrochemical reaction unit, a fuel cell power generation unit and an electrolysis cell unit are collectively referred to as an electrochemical reaction unit, and a fuel cell stack having multiple fuel cell power generation units and an electrolysis cell stack having multiple electrolysis cell units are collectively referred to as an electrochemical reaction cell stack. Furthermore, these issues are not limited to SOFCs and SOECs, but are also common to other types of fuel cells and electrolysis cells.

This specification discloses a 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 single cell, a single cell separator, and an interconnector. The electrochemical reaction single cell includes an electrolyte layer, and an air electrode and a fuel electrode that face each other in a first direction with the electrolyte layer in between. The single cell separator is a conductive member that is joined to the electrochemical reaction single cell and partitions a gas chamber facing the air electrode and a gas chamber facing the fuel electrode. The interconnector is a conductive member that is arranged to face a specific electrode, which is one of the fuel electrode and the air electrode, in the first direction and is electrically connected to the specific electrode. In at least one specific cross section along the first direction, the interconnector has a corner that is approximately perpendicular to the first direction and connects a surface that at least a portion of which faces the specific electrode with a surface facing the outer periphery, and that satisfies the following conditions: (1) the corner faces the single cell separator in the first direction, and (2) the corner does not include a portion that is bent at an angle of 90 degrees or less.

In this electrochemical reaction unit, in at least one specific cross section along the first direction, the interconnector has a specific corner that satisfies the following conditions: (1) it faces the single cell separator in the first direction, and (2) it does not include a portion that is bent at an angle of 90 degrees or less. This makes it possible to suppress electric field concentration at the specific corner. Therefore, according to this electrochemical reaction unit, even if the distance between the specific corner of the interconnector and the single cell separator becomes small, it is possible to suppress the occurrence of a short circuit between the two, and to suppress damage to the electrochemical reaction single cell due to the short circuit.

(2) The electrochemical reaction unit may further include an insulating member disposed between the corner of the interconnector and the single cell separator in the gas chamber facing the specific electrode, and the specific corner may be configured to face the single cell separator in the first direction without the insulating member. According to this electrochemical reaction unit, in a position where a short circuit is likely to occur between the corner of the interconnector and the single cell separator because no insulating member is disposed, the corner at the position is made a specific corner that can suppress electric field concentration, thereby suppressing the occurrence of the short circuit and suppressing damage to the electrochemical reaction single cell due to the short circuit.

(3) The electrochemical reaction unit may further include a conductive interconnector separator that is joined to the interconnector and partitions a gas chamber facing the specific electrode, and the specific corner may be a corner located on the outer periphery of the interconnector when viewed in the first direction. According to this electrochemical reaction unit, by making a corner located on the outer periphery of the interconnector, where electric field concentration is likely to occur, into a specific corner that can suppress electric field concentration, it is possible to suppress the occurrence of a short circuit between the interconnector and the single cell separator at the corner, and to suppress damage to the electrochemical reaction single cell due to the short circuit.

(4) In the electrochemical reaction unit, when viewed in the first direction, the contour line of the corner of the interconnector may be configured not to include a portion that is bent at an angle of 90 degrees or less. According to this electrochemical reaction unit, it is possible to suppress electric field concentration at the position of the contour line of the corner of the interconnector, and as a result, it is possible to effectively suppress the occurrence of a short circuit between the interconnector and the single cell separator.

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), an electrochemical reaction cell stack (fuel cell stack or electrolysis cell stack) having multiple electrochemical reaction units, or a manufacturing method thereof.

FIG. 1 is a perspective view showing an external configuration of a fuel cell stack 100 according to an embodiment of the present invention; 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. FIG. 2 is an explanatory diagram showing a YZ cross-sectional configuration of the fuel cell stack 100 taken along the line III-III 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 YZ cross-sectional configuration of two adjacent power generating units 102 at the same position as the cross-section shown in FIG. 3 . FIG. 6 is an explanatory diagram showing the XY cross-sectional configuration of the power generating unit 102 at the position VI-VI in FIG. FIG. 7 is an explanatory diagram showing the XY cross-sectional configuration of the power generating unit 102 taken along the line VII-VII in FIG. 4. FIG. 5 is an explanatory diagram showing an enlarged XZ cross-sectional configuration of a part (part X1 in FIG. 4) of the power generation unit 102. FIG. 7 is an explanatory diagram showing an enlarged YZ cross-sectional configuration of another part (part X2 in FIG. 5) of the power generating unit 102. FIG. 13 is an explanatory diagram showing the configuration of a power generation unit 102Z in a comparative example. FIG. 13 is an explanatory diagram showing the configuration of a power generation unit 102 in a modified example. FIG. 13 is an explanatory diagram showing the configuration of a power generation unit 102 in another modified example. FIG. 13 is an explanatory diagram showing the configuration of a power generation unit 102 in another modified example.

A. Embodiments:
A-1. Configuration:
(Configuration of fuel cell stack 100)
FIG. 1 is a perspective view showing the external configuration of a fuel cell stack 100 in this embodiment, FIG. 2 is an explanatory diagram showing the XZ cross-sectional configuration of the fuel cell stack 100 at the position II-II in FIG. 1 (and FIG. 6 and FIG. 7 described later), and FIG. 3 is an explanatory diagram showing the YZ cross-sectional configuration of the fuel cell stack 100 at the position III-III in FIG. 1 (and FIG. 6 and FIG. 7 described later). Each figure shows mutually orthogonal XYZ axes for specifying directions. In this specification, for convenience, the positive direction of the Z axis is called the upward direction, and the negative direction of the Z axis is called the downward direction, but the fuel cell stack 100 may actually be installed in a direction different from these directions. The same applies to FIG. 4 and subsequent figures.

The fuel cell stack 100 comprises a plurality (seven in this embodiment) of fuel cell power generation units (hereinafter simply referred to as "power generation units") 102, a pair of terminal plates 70, 80, 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). The arrangement direction (Z-axis direction) is an example of the first direction in the claims.

One of the pair of terminal plates 70, 80 (hereinafter referred to as the "upper terminal plate 70") is disposed on the upper side of an assembly (hereinafter referred to as the "power generation block 103") consisting of seven power generation units 102, and one of the pair of end plates 104, 106 (hereinafter referred to as the "upper end plate 104") is disposed on the upper side of the upper terminal plate 70. The other of the pair of terminal plates 70, 80 (hereinafter referred to as the "lower terminal plate 80") is disposed on the lower side of the power generation block 103, and the other of the pair of end plates 104, 106 (hereinafter referred to as the "lower end plate 106") is disposed on the lower side of the lower terminal plate 80. An insulating sheet 92 is interposed between the upper terminal plate 70 and the upper end plate 104, and between the lower terminal plate 80 and the lower end plate 106. The insulating sheet 92 is made of, for example, a mica sheet, a ceramic fiber sheet, a ceramic powder sheet, a glass sheet, a glass ceramic composite, etc. More specifically, a cover separator 60 (described later) is interposed between the upper terminal plate 70 and the insulating sheet 92.

A plurality of holes (eight in this embodiment) that penetrate in the vertical direction are formed in the peripheral portion around the Z axis direction of each layer (power generation unit 102, terminal plates 70, 80, end plates 104, 106) that constitutes the fuel cell stack 100, and corresponding holes formed in each layer communicate with each other in the vertical direction to form communication holes 108 that extend in the vertical direction from the upper end plate 104 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.

A bolt 22 extending in the vertical direction is inserted into each communication hole 108, and the fuel cell stack 100 is fastened by the vertical compressive force of the bolt 22 and the nuts 24 fitted on both sides of the bolt 22. As shown in Figs. 2 and 3, an insulating sheet 26 is interposed between the nut 24 fitted on one side (upper side) of the bolt 22 and the upper surface of the upper end plate 104, and between the nut 24 fitted on the other side (lower side) of the bolt 22 and the lower surface of the lower end plate 106. However, at the location where the gas passage member 27 described later is provided, the gas passage member 27 and the insulating sheets 26 arranged on the upper and lower sides of the gas passage member 27 are interposed between the nut 24 and the surface of the lower end plate 106. The insulating sheet 26 is made of, for example, a mica sheet, a ceramic fiber sheet, a ceramic powder sheet, a glass sheet, a glass ceramic composite, etc.

The outer diameter of the shaft of each bolt 22 is smaller than the inner diameter of each communication hole 108. Therefore, a space is provided between the outer peripheral surface of the shaft of each bolt 22 and the inner peripheral surface of each communication hole 108. As shown in Figures 1 and 2, a space formed by a bolt 22 (bolt 22A) located near the midpoint of one side (the side on the positive X-axis side of two sides parallel to the Y-axis) on the outer periphery of the fuel cell stack 100 around the Z-axis direction and the communication hole 108 through which the bolt 22A is inserted 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 the oxidant gas OG is supplied to each power generating unit 102, and a space formed by a bolt 22 (bolt 22B) located near the midpoint of the side opposite to the side (the side on the negative X-axis side of two sides parallel to the Y-axis) and the communication hole 108 through which the bolt 22B is inserted functions as an oxidant gas discharge manifold 162 that discharges oxidant off-gas OOG, which is gas discharged from an air chamber 166 of each power generating unit 102, to the outside of the fuel cell stack 100. In this embodiment, air, for example, is used as the oxidant gas OG.

As shown in Figures 1 and 3, the space formed by the bolt 22 (bolt 22D) located near the midpoint of one side (the side on the positive Y-axis side of the two sides parallel to the X-axis) on the outer periphery of the fuel cell stack 100 around the Z-axis direction and the communication hole 108 through which the bolt 22D is inserted functions as a fuel gas supply manifold 171 through which fuel gas FG is introduced from outside the fuel cell stack 100 and the fuel gas FG is supplied to each power generation unit 102, and the space formed by the bolt 22 (bolt 22E) located near the midpoint of the opposite side (the side on the negative Y-axis side of the two sides parallel to the X-axis) and the communication hole 108 through which the bolt 22E is inserted functions as a fuel gas exhaust manifold 172 that exhausts fuel off-gas FOG, which is gas exhausted from the fuel chamber 176 of each power generation unit 102, to the outside of the fuel cell stack 100. In this embodiment, the fuel gas FG is, for example, hydrogen-rich gas obtained by reforming city gas.

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 branched from the side of the main body 28. The hole of the branch portion 29 is connected to the hole 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 bolt 22A forming the oxidizing gas supply manifold 161 is connected to the oxidizing gas supply manifold 161, and the hole of the main body 28 of the gas passage member 27 arranged at the position of the bolt 22B forming the oxidizing gas exhaust manifold 162 is connected to the oxidizing gas exhaust manifold 162. Also, as shown in FIG. 3, the hole in the body 28 of the gas passage member 27 located at the position of the bolt 22D that forms the fuel gas supply manifold 171 is connected to the fuel gas supply manifold 171, and the hole in the body 28 of the gas passage member 27 located at the position of the bolt 22E that forms the fuel gas exhaust manifold 172 is connected to the fuel gas exhaust manifold 172.

(Configuration of end plates 104, 106)
The pair of end plates 104, 106 are flat members having an approximately rectangular outer shape as viewed in the Z-axis direction, and are made of, for example, stainless steel. Holes 32, 34 penetrating in the Z-axis direction are formed near the centers of the pair of end plates 104, 106, respectively. As viewed in the Z-axis direction, the inner circumferential lines of the holes 32, 34 formed in each of the pair of end plates 104, 106 encompass each of the unit cells 110 described below. Therefore, the compressive force in the Z-axis direction by each bolt 22 and nut 24 acts mainly on the peripheral portion of each power generating unit 102 (the portion on the outer periphery of each of the unit cells 110 described below).

(Configuration of Terminal Plates 70, 80)
The pair of terminal plates 70, 80 are flat members having an approximately rectangular outer shape as viewed in the Z-axis direction, and are made of, for example, stainless steel. A hole 71 is formed near the center of the upper terminal plate 70, penetrating in the Z-axis direction. As viewed in the Z-axis direction, the inner circumferential line of the hole 71 formed in the upper terminal plate 70 includes each of the unit cells 110 described later. In this embodiment, as viewed in the Z-axis direction, the inner circumferential line of the hole 71 formed in the upper terminal plate 70 approximately coincides with the inner circumferential line of the hole 32 formed in the upper end plate 104. As viewed in the Z-axis direction, the upper terminal plate 70 has a protruding portion 78 that protrudes outward from the outer circumferential line of the upper end plate 104, and the protruding portion 78 functions as a positive output terminal of the fuel cell stack 100. In addition, the lower terminal plate 80 has a protrusion 88 that protrudes outward from the outer periphery of the lower end plate 106 when viewed in the Z-axis direction, and the protrusion 88 functions as the negative output terminal of the fuel cell stack 100.

(Configuration of power generation unit 102)
Fig. 4 is an explanatory diagram showing the XZ cross-sectional configuration of two adjacent power generating units 102 (the two power generating units 102 located at the top) at the same position as the cross section shown in Fig. 2, and Fig. 5 is an explanatory diagram showing the YZ cross-sectional configuration of two adjacent power generating units 102 (the two power generating units 102 located at the top) at the same position as the cross section shown in Fig. 3. Fig. 6 is an explanatory diagram showing the XY cross-sectional configuration of the power generating unit 102 at the position VI-VI in Fig. 4, and Fig. 7 is an explanatory diagram showing the XY cross-sectional configuration of the power generating unit 102 at the position VII-VII in Fig. 4.

As shown in Figures 4 and 5, the power generation unit 102 includes a fuel cell unit (hereinafter referred to as a "unit cell") 110, a unit cell separator 120, an air electrode side frame 130, a fuel electrode side frame 140, a fuel electrode side current collecting member 148, and a pair of interconnectors 190 and a pair of interconnector separators (hereinafter referred to as "IC separators") 180 that constitute the uppermost and lowermost layers of the power generation unit 102. Holes corresponding to the communication holes 108 through which the bolts 22 described above are inserted are formed in the peripheral portions around the Z-axis direction of the unit cell separator 120, the air electrode side frame 130, the fuel electrode side frame 140, and the IC separator 180.

The single cell 110 includes an electrolyte layer 112, an air electrode 114 arranged on one side (upper side) of the electrolyte layer 112 in the Z-axis direction, a fuel electrode 116 arranged on the other side (lower side) of the electrolyte layer 112 in the Z-axis direction, and an intermediate layer 118 arranged between the electrolyte layer 112 and the air electrode 114. Note that the single cell 110 of this embodiment is an anode-supported single cell in which the fuel electrode 116 supports the other layers (electrolyte layer 112, air electrode 114, intermediate layer 118) that constitute the single cell 110.

The electrolyte layer 112 is a substantially rectangular flat-plate member as viewed in the Z-axis direction, and is configured to include a solid oxide (e.g., YSZ (yttria-stabilized zirconia)). That is, the single 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 smaller than the electrolyte layer 112 as viewed in the Z-axis direction, and is configured to include, 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 having substantially the same size as the electrolyte layer 112 as 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 intermediate layer 118 is a substantially rectangular flat-plate member having substantially the same size as the air electrode 114 as viewed in the Z-axis direction, and is configured to include, for example, GDC (gadolinium-doped ceria) and YSZ. The intermediate layer 118 has the function of suppressing the reaction of an element (e.g., Sr) diffused from the cathode 114 with an element (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 with a substantially rectangular hole 121 formed near the center in the Z-axis direction, and is made of, for example, metal. The portion surrounding the hole 121 in the single cell separator 120 (hereinafter referred to as the "through hole surrounding portion") faces the peripheral portion of the surface of the electrolyte layer 112 on the side of the air electrode 114 (upper side). The single cell separator 120 is joined to the electrolyte layer 112 (single cell 110) by a joint portion 124 formed of a brazing material (e.g., Ag brazing) arranged in the facing portion. The single cell separator 120 divides an air chamber 166 facing the air electrode 114 and a fuel chamber 176 facing the fuel electrode 116, and gas leakage (cross leakage) from one electrode side to the other electrode side at the peripheral portion of the single cell 110 is suppressed.

The single cell separator 120 includes an inner portion 126 including the through-hole periphery (the portion surrounding the hole 121) of the single cell separator 120, an outer portion 127 located on the outer periphery side of 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 substantially flat plates extending in a direction substantially perpendicular to the Z-axis direction. The connecting portion 128 is curved so as to protrude downward from both the inner portion 126 and the outer portion 127. The lower portion (fuel chamber 176 side) of the connecting portion 128 is a convex portion, and the upper portion (air chamber 166 side) of the connecting portion 128 is a concave portion. Therefore, the connecting portion 128 includes a portion whose position in the Z-axis direction is different from that of the inner portion 126 and the outer portion 127.

A glass seal portion 125 containing glass is disposed near the 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 around the through hole of 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.

4 to 6, the interconnector 190 is a conductive member having a flat plate portion 150 having a substantially rectangular flat plate shape and 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 is formed of a metal (e.g., ferritic stainless steel). As shown in FIG. 4, the outer periphery of the interconnector 190 as viewed in the Z-axis direction faces the single cell separator 120 in the Z-axis direction. In this embodiment, a conductive coating layer 194 made of, for example, a spinel-type oxide is formed on the surface of the interconnector 190 (the surface facing the air chamber 166). Hereinafter, the interconnector 190 covered with the coating layer 194 is simply referred to as the interconnector 190. The interconnector 190 (more specifically, each air electrode side current collecting portion 134 of the interconnector 190) is electrically connected to the air electrode 114 of the single cell 110 by being joined to the air electrode 114 via a conductive bonding material 196 made of, for example, a spinel-type oxide. The interconnector 190 ensures electrical conduction between the power generating units 102 and prevents the reaction gases from mixing between the power generating units 102. In this embodiment, when two power generating units 102 are arranged adjacent to each other, one interconnector 190 is shared by the two adjacent power generating units 102. That is, the upper interconnector 190 in a certain power generating unit 102 is made of the same material as the lower interconnector 190 in another power generating unit 102 adjacent to the upper side of the power generating unit 102. In addition, the lower interconnector 190 of the power generating unit 102 located at the lowermost position in the fuel cell stack 100 is electrically connected to the lower terminal plate 80 via a conductive bonding material 196. In addition, 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 terminal plate 70 via an IC separator 180 and/or other members (connecting member 48, cover member 50, cover separator 60) described later. The air electrode 114 is an example of a specific electrode within the scope of the claims.

The IC separator 180 is a frame-shaped conductive member with a substantially rectangular hole 181 formed near the center that penetrates in the Z-axis direction, and is made of, for example, metal. The portion of the IC separator 180 that surrounds the 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 interconnector 190 (the flat portion 150 thereof). Of a pair of IC separators 180 included in a certain generating unit 102, the upper IC separator 180 partitions the air chamber 166 of the generating unit 102 and the fuel chamber 176 of the other generating unit 102 adjacent to the generating unit 102 on the upper side. In addition, of the pair of IC separators 180 included in a certain generating unit 102, the lower IC separator 180 separates the fuel chamber 176 of the generating unit 102 from the air chamber 166 of the other generating unit 102 adjacent to the generating unit 102 on the lower side. In this way, the IC separator 180 suppresses gas leakage between the generating units 102 at the periphery of the generating units 102.

The IC separator 180 includes an inner portion 186 including the through-hole periphery (the portion surrounding the hole 181) of the IC separator 180, an outer portion 187 located on the outer periphery side of 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 substantially flat plates extending in a direction substantially perpendicular to the Z-axis direction. The connecting portion 188 is curved so as to protrude downward from both the inner portion 186 and the outer portion 187. The lower portion (air chamber 166 side) of the connecting portion 188 is a convex portion, and the upper portion (fuel chamber 176 side) of the connecting portion 188 is a concave portion. Therefore, the connecting portion 188 includes a portion whose position in the Z-axis direction is different from that of the inner portion 186 and the outer portion 187.

6, the air electrode side frame 130 is a frame-shaped member with a substantially rectangular hole 131 formed near the center penetrating in the Z-axis direction, and is formed of an insulator such as mica. The hole 131 of the air electrode side frame 130 constitutes an air chamber 166 facing the air electrode 114. The air electrode side frame 130 is in contact with the peripheral portion of the surface of the single cell separator 120 opposite the side facing the electrolyte layer 112 (upper side) and the peripheral portion of the surface of the upper IC separator 180 facing the air chamber 166 (lower side), and functions as a sealing member that ensures gas sealing between the two (i.e., gas sealing of the air chamber 166). In addition, the air electrode side frame 130 electrically insulates a pair of IC separators 180 included in the power generation unit 102 (i.e., a pair of interconnectors 190). In addition, the air electrode side frame 130 is formed with an oxidant gas supply communication hole 132 that connects the oxidant gas supply manifold 161 to the air chamber 166, and an oxidant gas discharge communication hole 133 that connects the air chamber 166 to the oxidant gas discharge manifold 162.

7, the fuel electrode side frame 140 is a frame-shaped conductive 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 of the fuel electrode side frame 140 constitutes a fuel chamber 176 facing the fuel electrode 116. The fuel electrode side frame 140 is in contact with the peripheral portion of the surface of the side (lower side) of the single cell separator 120 that faces the electrolyte layer 112, and the peripheral portion of the surface of the side (upper side) of the lower IC separator 180 that faces the fuel chamber 176. In addition, the fuel electrode side frame 140 is formed with a fuel gas supply communication hole 142 that communicates the fuel gas supply manifold 171 and the fuel chamber 176, and a fuel gas discharge communication hole 143 that communicates the fuel chamber 176 and the fuel gas discharge manifold 172.

The fuel electrode side current collecting member 148 is disposed in the fuel chamber 176. The fuel electrode side current collecting member 148 has a conductive portion 144 and an elastic portion 149. The conductive portion 144 is a portion that electrically connects the fuel electrode 116 and the interconnector 190, and is formed of, for example, nickel, a nickel alloy, stainless steel, or the like. The conductive portion 144 has an electrode facing portion 145 that contacts the lower surface of the fuel electrode 116, an interconnector facing portion 146 that contacts the upper surface of the interconnector 190, and a connecting portion 147 that connects the electrode facing portion 145 and the interconnector facing portion 146. The elastic portion 149 is a portion for ensuring the elasticity of the fuel electrode side current collecting member 148, and is formed of, for example, mica, or the like. The interconnector facing portion 146 of the conductive portion 144 is disposed between the interconnector 190 and the elastic portion 149 in the Z-axis direction, and the electrode facing portion 145 of the conductive portion 144 is disposed between the fuel electrode 116 and the elastic portion 149 in the Z-axis direction. This allows the fuel electrode side current collecting member 148 to follow the deformation of the power generating unit 102 due to temperature cycles and reactant gas pressure fluctuations, and the electrical connection between the fuel electrode 116 and the interconnector 190 via the fuel electrode side current collecting member 148 is well maintained. The fuel electrode side current collecting member 148 is produced, for example, by making cuts in a flat plate-shaped material (for example, nickel foil having a thickness of 10 to 200 μm), disposing a sheet-shaped elastic portion 149 having a plurality of holes formed therein on the material, and bending and raising the plurality of rectangular portions to sandwich the elastic portion 149. Each bent rectangular portion becomes the electrode facing portion 145, the flat portion with holes other than the bent portions becomes the interconnector facing portion 146, and the portion connecting the electrode facing portion 145 and the interconnector facing portion 146 becomes the connection portion 147.

As shown in Figures 4 to 7, each generating unit 102 of this embodiment further includes a felt member 41 arranged in the air chamber 166 and the fuel chamber 176. The felt member 41 is an insulating member made of an alumina-silica (silicon dioxide) felt material. That is, the felt member 41 contains alumina, which is a ceramic, and a silica component. The inclusion of alumina in the felt member 41 can improve the heat resistance and flexibility of the felt member 41. The felt member 41 is an example of an insulating member in the claims.

5 and 6, in the air chamber 166, the felt members 41 are filled at both ends in the direction (Y-axis direction) perpendicular to the main flow direction (X-axis direction) of the oxidizer gas OG (positions that do not overlap with the air electrode 114 of the single cell 110 in the Z-axis direction). A part of the felt member 41 (a part closer to the center of the single cell 110) is disposed between the outer periphery of the interconnector 190 (including the corner portion CP described later) and the single cell separator 120. Therefore, at the location where the felt member 41 is disposed, the outer periphery of the interconnector 190 faces the single cell separator 120 via the felt member 41 in the Z-axis direction. Also, as shown in FIGS. 4 and 7, in the fuel chamber 176, the felt members 41 are filled at both ends in the direction (X-axis direction) perpendicular to the main flow direction (Y-axis direction) of the fuel gas FG (positions that do not overlap with the air electrode 114 of the single cell 110 in the Z-axis direction). The presence of the felt member 41 can prevent the oxidant gas OG supplied to the air chamber 166 or the fuel gas FG supplied to the fuel chamber 176 from passing through areas that do not contribute much to power generation and being discharged from the air chamber 166 or the fuel chamber 176, improving power generation efficiency.

As shown in FIG. 4 and FIG. 5, the fuel cell stack 100 of this embodiment includes a cover member 50 and a cover separator 60 arranged above the uppermost generating unit 102 (hereinafter also referred to as the "specific generating unit 102X"). The cover member 50 is a flat plate-shaped member that is approximately rectangular when viewed in the Z-axis direction, and is made of a conductive material (e.g., metal). The cover member 50 is arranged in a hole 71 formed in the upper terminal plate 70, and is adjacent to the upper interconnector 190 included in the specific generating unit 102X while being spaced apart in the Z-axis direction. That is, a space (a space formed by the hole 71 of the upper terminal plate 70, hereinafter referred to as the "specific space 58") is formed between the cover member 50 and the upper interconnector 190 included in the specific generating unit 102X. The specific space 58 is located above the multiple single cells 110 (all the single cells 110) included in the fuel cell stack 100.

The cover separator 60 is a frame-like member with a substantially rectangular hole 61 formed near the center that penetrates in the Z-axis direction, and is made of, for example, metal. The portion of the cover separator 60 that surrounds the hole 61 (hereinafter referred to as the "through hole surrounding portion") is joined to the upper surface of the peripheral portion of the cover member 50, for example, by welding. The peripheral portion of the cover separator 60 is joined to the upper surface of the terminal plate 70, for example, by brazing. The specific space 58 is defined by the cover separator 60 (and the IC separator 180 joined to the upper interconnector 190 included in the specific power generation unit 102X).

The cover separator 60 includes an inner portion 66 including the through-hole periphery (the portion surrounding the hole 61) of the cover separator 60, an outer portion 67 located on the outer periphery side of the inner portion 66, and a connecting portion 68 connecting the inner portion 66 and the outer portion 67. In this embodiment, the inner portion 66 and the outer portion 67 are substantially flat plates extending in a direction substantially perpendicular to the Z-axis direction. The connecting portion 68 is curved so as to protrude downward from both the inner portion 66 and the outer portion 67. The lower portion (the specific space 58 side) of the connecting portion 68 is a convex portion, and the upper portion (the external space side) of the connecting portion 68 is a concave portion. Therefore, the connecting portion 68 includes a portion whose position in the Z-axis direction is different from that of the inner portion 66 and the outer portion 67.

The fuel cell stack 100 of this embodiment further includes a connection member 48 disposed in the specific space 58. In this embodiment, the connection member 48 has the same configuration as the fuel electrode side current collecting member 148. That is, the connection member 48 has a conductive portion 44 and an elastic portion 49. The conductive portion 44 is a portion that electrically connects the cover member 50 and the upper interconnector 190 included in the specific power generating unit 102X, and is formed of, for example, nickel, a nickel alloy, stainless steel, or the like. The conductive portion 44 has a cover member facing portion 45 that contacts the lower surface of the cover member 50, an interconnector facing portion 46 that contacts the upper surface of the interconnector 190, and a connecting portion 47 that connects the cover member facing portion 45 and the interconnector facing portion 46. The elastic portion 49 is a portion for ensuring the elasticity of the connection member 48, and is formed of, for example, mica, or the like. The interconnector facing portion 46 of the conductive portion 44 is disposed between the interconnector 190 and the elastic portion 49 in the Z-axis direction, and the cover member facing portion 45 of the conductive portion 44 is disposed between the cover member 50 and the elastic portion 49 in the Z-axis direction. The connection member 48 can be manufactured, for example, by a method similar to the manufacturing method of the fuel electrode side current collecting member 148 described above.

A-2. Operation of the fuel cell stack 100:
2 and 4, when the oxidant gas OG is supplied through a gas pipe (not shown) connected to the branch portion 29 of the gas passage member 27 provided at the position of the oxidant gas 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 is supplied from the oxidant gas supply manifold 161 to the air chamber 166 through the oxidant gas supply passage hole 132 of each power generating unit 102. Also, as shown in Figs. 3 and 5, when the fuel gas FG is supplied through a gas pipe (not shown) connected to the branch portion 29 of the gas passage member 27 provided at the position of the fuel gas 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 is supplied to the fuel chamber 176 from the fuel gas supply manifold 171 through the fuel gas supply passage hole 142 of each power generating unit 102.

When the oxidant gas OG is supplied to the air chamber 166 of each power generation unit 102 and the fuel gas FG is supplied to the fuel chamber 176, power is generated in the single cell 110 by an electrochemical reaction of the oxidant gas OG and the fuel gas FG. This power generation reaction is an exothermic reaction. In each power generation unit 102, the air electrode 114 of the single cell 110 is electrically connected to the interconnector 190 via a conductive bonding material 196, and the fuel electrode 116 is electrically connected to the interconnector 190 via the fuel electrode side current collecting member 148. That is, the multiple power generation units 102 included in the fuel cell stack 100 are electrically connected in series. In addition, in the fuel cell stack 100, the upper interconnector 190 of the power generation unit 102 located at the top is electrically connected to the upper terminal plate 70, and the lower interconnector 190 of the power generation unit 102 located at the bottom is electrically connected to the lower terminal plate 80. Therefore, the electrical energy generated in each power generating unit 102 is extracted from a pair of terminal plates 70, 80 that 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 by the heat generated by power generation.

As shown in Figs. 2 and 4, the oxidant off-gas OOG discharged from the air chamber 166 of each power generation unit 102 is discharged to the oxidant gas discharge manifold 162 through the oxidant gas discharge communication hole 133, and then through the holes in the main body 28 and the branching part 29 of the gas passage member 27 provided at the position of the oxidant gas discharge manifold 162, and is discharged to the outside of the fuel cell stack 100 through the gas pipe (not shown) connected to the branching part 29. Also, as shown in Figs. 3 and 5, the fuel off-gas FOG discharged from the fuel chamber 176 of each power generation unit 102 is discharged to the fuel gas discharge manifold 172 through the fuel gas discharge communication hole 143, and then through the holes in the main body 28 and the branching part 29 of the gas passage member 27 provided at the position of the fuel gas discharge manifold 172, and is discharged to the outside of the fuel cell stack 100 through the gas pipe (not shown) connected to the branching part 29.

A-3. Detailed configuration of the interconnector 190:
Next, a detailed configuration of the interconnector 190 in the power generating unit 102 of this embodiment will be described. Fig. 8 is an explanatory diagram showing an enlarged XZ cross-sectional configuration of a part (part X1 in Fig. 4) of the power generating unit 102, and Fig. 9 is an explanatory diagram showing an enlarged YZ cross-sectional configuration of another part (part X2 in Fig. 5) of the power generating unit 102. In this embodiment, the detailed configuration of the interconnector 190 described below is adopted in all the power generating units 102 included in the fuel cell stack 100.

8 and 9, in a cross section along the Z-axis direction (e.g., an XZ cross section and a YZ cross section), the interconnector 190 has a corner CP. The corner CP is a portion that connects a surface S1 that is approximately perpendicular to the Z-axis direction and at least a portion of which faces the air electrode 114, and a surface S2 that faces the outer periphery. Note that a direction that is approximately perpendicular to the Z-axis direction means that the inclination of the direction relative to a direction strictly perpendicular to the Z-axis direction is within ±10 degrees. In this embodiment, at least a portion of the corner CP of the interconnector 190 is present on the outer periphery of the interconnector 190 when viewed in the Z-axis direction. The corner CP of the interconnector 190 may be present at a position other than the outer periphery of the interconnector 190 when viewed in the Z-axis direction.

As shown in FIG. 9, some of the corners CP of the interconnector 190 (hereinafter referred to as "general corners GCP") have portions bent at an angle of 90 degrees (or less). In this embodiment, all of the corners CP that face the single cell separator 120 in the Z-axis direction via the felt member 41 are general corners GCP.

On the other hand, as shown in FIG. 8, another part of the corners CP of the interconnector 190 (hereinafter referred to as the "special corners SCP") has a chamfered shape. That is, the special corners SCP do not include any parts bent at an angle of 90 degrees or less. In this embodiment, all corners CP that face the single cell separator 120 in the Z-axis direction without the felt member 41 in between are special corners SCP. In this embodiment, the special corners SCP have an R shape (a shape like an R chamfer). Also, in this embodiment, only a part of the surface S2 facing the outer periphery of the interconnector 190 described above has an approximately arc shape, and the remaining part is approximately parallel to the Z-axis direction. The special corners SCP can be formed, for example, by polishing, cutting, etc.

Thus, in the power generation unit 102 of this embodiment, in at least one cross section along the Z-axis direction (hereinafter referred to as the "specific cross section"), the interconnector 190 has a corner portion CP that connects a surface S1 that is approximately perpendicular to the Z-axis direction and at least a portion of which faces the air electrode 114, with a surface S2 facing the outer periphery, and that satisfies the following conditions: (1) it faces the single cell separator 120 in the Z-axis direction, and (2) it does not include a portion that is bent at an angle of 90 degrees or less.

Also, as shown in FIG. 6, in the power generation unit 102 of this embodiment, when viewed in the Z-axis direction, the contour line of the corner CP of the interconnector 190 is approximately rectangular, and has a shape with four chamfered corners. In other words, when viewed in the Z-axis direction, the contour line of the corner CP of the interconnector 190 does not include a portion bent at an angle of 90 degrees or less. Such a shape of the interconnector 190 can be achieved, for example, by polishing, cutting, shearing, etc.

A-4. Advantages of this embodiment:
As described above, the power generation unit 102 of this embodiment includes a single cell 110, a single cell separator 120, and an interconnector 190. The single cell 110 includes an electrolyte layer 112, 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 single cell separator 120 is a conductive member that is joined to the single cell 110 and partitions an air chamber 166 facing the air electrode 114 and a fuel chamber 176 facing the anode 116. The interconnector 190 is a conductive member that is disposed to face the air electrode 114 in the Z-axis direction and is electrically connected to the air electrode 114. Furthermore, in the power generation unit 102 of this embodiment, in a specific cross section (for example, the cross section shown in Figure 8), which is at least one cross section along the Z-axis direction, the interconnector 190 has a corner portion CP that connects a surface S1 that is approximately perpendicular to the Z-axis direction and at least a portion of which faces the air electrode 114, to a surface S2 facing the outer periphery, and that satisfies the following conditions: (1) it faces the single cell separator 120 in the Z-axis direction, and (2) it does not include a portion that is bent at an angle of 90 degrees or less.

In this way, in the power generating unit 102 of this embodiment, the interconnector 190 has a specific corner portion SCP in a specific cross section, so that, as described below, it is possible to suppress the occurrence of a short circuit between the corner portion CP of the interconnector 190 and the single cell separator 120, and to suppress damage to the single cell 110 due to the short circuit.

Figure 10 is an explanatory diagram showing the configuration of a power generation unit 102Z in a comparative example. In the power generation unit 102Z in the comparative example, all of the corners CP of the interconnector 190 are general corners GCP, which have a portion bent at an angle of 90 degrees (or less). That is, as shown in Figure 10, among the corners CP of the interconnector 190, the corners CP that face the single cell separator 120 in the Z-axis direction without the felt member 41 in between are also general corners GCP. Since the general corners GCP have a portion bent at an angle of 90 degrees (or less), the electric field is likely to concentrate in that portion.

Here, in the generating unit 102, deformation such as warping occurs in each component due to changes in temperature and gas pressure, and as a result, the distance between the corner CP of the interconnector 190 and the single cell separator 120 may become smaller. In the generating unit 102Z in the comparative example, among the corners CP of the interconnector 190, the corner CP that faces the single cell separator 120 in the Z-axis direction without the felt member 41 is a general corner GCP where electric field concentration is likely to occur. Therefore, if the distance between the corner CP of the interconnector 190 and the single cell separator 120 becomes small, a short circuit may occur between them, and if such a short circuit occurs, the single cell 110 may be damaged. In addition, damage to the single cell 110 due to the short circuit can occur, for example, when a current continues to flow through the electrical path via the short circuit, causing a shortage of fuel gas FG on the fuel electrode 116 side, and the Ni contained in the fuel electrode 116 oxidizes abnormally and expands due to the shortage of fuel gas FG, resulting in cracks and breaks in the electrolyte layer 112.

In contrast, in the power generating unit 102 of this embodiment, the interconnector 190 has a specific corner SCP that satisfies the following conditions: (1) it faces the single cell separator 120 in the Z-axis direction, and (2) it does not include a portion that is bent at an angle of 90 degrees or less. This makes it possible to suppress electric field concentration at the specific corner SCP. Therefore, according to the power generating unit 102 of this embodiment, even if the distance between the specific corner SCP of the interconnector 190 and the single cell separator 120 becomes small, it is possible to suppress the occurrence of a short circuit between the two, and to suppress damage to the single cell 110 due to the short circuit.

The power generating unit 102 of this embodiment further includes a felt member 41. The felt member 41 is an insulating member disposed between the corner CP of the interconnector 190 and the single cell separator 120 in the air chamber 166 facing the air electrode 114. The specific corner SCP of the interconnector 190 faces the single cell separator 120 in the Z-axis direction without the felt member 41 in between. Therefore, according to the power generating unit 102 of this embodiment, in a position where a short circuit is likely to occur between the corner CP of the interconnector 190 and the single cell separator 120 because the felt member 41 is not disposed, the occurrence of the short circuit can be suppressed by making the corner CP at the position the specific corner SCP.

The power generating unit 102 of this embodiment further includes an IC separator 180. The IC separator 180 is a conductive member that is joined to the interconnector 190 and divides the air chamber 166 facing the air electrode 114. In the power generating unit 102 of this embodiment, the specific corner SCP of the interconnector 190 is a corner CP located on the outer periphery of the interconnector 190 when viewed in the Z-axis direction. Therefore, according to the power generating unit 102 of this embodiment, in the corner CP located on the outer periphery of the interconnector 190 where electric field concentration is likely to occur, the corner CP is made the specific corner SCP, thereby suppressing the occurrence of a short circuit between the interconnector 190 and the single cell separator 120 at the corner CP.

In addition, in the power generating unit 102 of this embodiment, when viewed in the Z-axis direction, the contour line of the corner CP of the interconnector 190 does not include a portion that is bent at an angle of 90 degrees or less. Therefore, according to the power generating unit 102 of this embodiment, it is possible to suppress electric field concentration at the position of the contour line of the corner CP of the interconnector 190, and as a result, it is possible to effectively suppress the occurrence of a short circuit between the interconnector 190 and the single cell separator 120.

B. 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 of the invention. For example, the following modifications are also possible.

The configurations of the fuel cell stack 100 and the power generating unit 102 in the above embodiment are merely examples and can be modified in various ways. FIG. 11 is an explanatory diagram showing the configuration of the power generating unit 102 in a modified example. In the power generating unit 102 of the modified example shown in FIG. 11, the specific corner SCP of the interconnector 190 has an R-shape (a shape similar to a chamfered R-shape), similar to the power generating unit 102 in the above embodiment. However, in the power generating unit 102 of the modified example shown in FIG. 11, substantially the entire surface S2 facing the outer periphery of the interconnector 190 is substantially arc-shaped, and the surface S2 does not have any portion parallel to the Z-axis direction.

Figure 12 is an explanatory diagram showing the configuration of a power generation unit 102 in another modified example. In the power generation unit 102 of the modified example shown in Figure 12, the specific corner SCP of the interconnector 190 has a shape similar to C-chamfering. In addition, only a part of the surface S2 facing the outer periphery of the interconnector 190 is inclined with respect to the Z-axis direction, and the remaining part is approximately parallel to the Z-axis direction. Note that in the power generation unit 102 of the modified example shown in Figure 12, the configuration may be such that approximately the entire surface S2 facing the outer periphery is inclined with respect to the Z-axis direction, and the surface S2 does not have a part parallel to the Z-axis direction.

Figure 13 is an explanatory diagram showing the configuration of a power generation unit 102 in another modified example. In the power generation unit 102 of the modified example shown in Figure 13, the IC separator 180 is not provided, and the interconnector 190 is configured to extend to the outer periphery of the fuel cell stack 100. In other words, in the power generation unit 102 of the modified example shown in Figure 13, the interconnector 190 and the IC separator 180 in the power generation unit 102 of the above-mentioned embodiment are configured as an integrated member. On the surface of the side (lower side) of the interconnector 190 that faces the air electrode 114 in the integrated member, a step is provided at the boundary between the center and the outer periphery, such that the outer periphery is concave. In the power generation unit 102 of the modified example shown in Figure 13, this step corresponds to the corner CP of the interconnector 190. In the modified power generating unit 102 shown in FIG. 13, among the corners CP present in the step portion of the interconnector 190, all of the corners CP that face the single cell separator 120 in the Z-axis direction without the felt member 41 in between are specific corners SCP. Therefore, according to the modified power generating unit 102 shown in FIG. 13, like the power generating unit 102 of the above-mentioned embodiment, it is possible to suppress the occurrence of a short circuit between the corners CP of the interconnector 190 and the single cell separator 120, and to suppress damage to the single cell 110 due to the short circuit.

The shape of the specific corner portion SCP on the cross section of the power generating unit 102 along the Z-axis direction in the above embodiment (or modified example (similar below)) is merely an example and can be modified in various ways. For example, in the above embodiment, the shape of the specific corner portion SCP is substantially arc-shaped, but it may be a curved shape other than an arc.

In the above embodiment, all corners CP that face the single cell separator 120 in the Z-axis direction without the felt member 41 are specific corners SCP, but only a portion of the corners CP may be specific corners SCP and the remaining portion may be general corners GCP. Also, in the above embodiment, all corners CP that face the single cell separator 120 in the Z-axis direction without the felt member 41 are general corners GCP, but at least a portion of the corners CP may be specific corners SCP.

In the above embodiment, a felt member 41 is used as the insulating member placed in the air chamber 166 and/or the fuel chamber 176, but a member made of another insulating material may be used as the insulating member. Also, it is not necessarily necessary to place an insulating member in the air chamber 166 and/or the fuel chamber 176, and the insulating member may be omitted.

In the above embodiment, when viewed in the Z-axis direction, the contour line of the corner portion CP of the interconnector 190 does not include a portion bent at an angle of 90 degrees or less, but the contour line may include a portion bent at an angle of 90 degrees or less.

In the above embodiment, in the cross section of the power generating unit 102 along the Z-axis direction, the corner CP of the interconnector 190 is a portion that connects the surface S1 facing the air electrode 114 to the surface S2 facing the outer periphery, but the corner CP of the interconnector 190 may instead be a portion that connects the surface of the interconnector 190 that faces the fuel electrode 116 to the surface facing the outer periphery. In this case, the fuel electrode 116 corresponds to the specific electrode in the claims.

In the above embodiment, the detailed configuration of the interconnector 190 described above (the interconnector 190 has a specific corner portion SCP) is adopted in all of the power generation units 102 included in the fuel cell stack 100, but it is sufficient that the configuration is adopted in at least one of the power generation units 102 included in the fuel cell stack 100.

In the above embodiment, the holes 32, 34 are formed in the pair of end plates 104, 106, but the holes 32, 34 do not have to be formed in at least one of the pair of end plates 104, 106. Also, in the above embodiment, the fuel cell stack 100 includes a pair of terminal plates 70, 80, but other members (e.g., the pair of end plates 104, 106) may also function as terminal plates, and the terminal plates 70, 80 as dedicated members may be omitted.

In the above embodiment, the single cell separator 120 has a curved connecting portion 128 that protrudes downward from both the inner portion 126 and the outer portion 127, but the shape of the connecting portion 128 may be other shapes. Also, the single cell separator 120 does not have to have the connecting portion 128. The same applies to the connecting portion 188 in the IC separator 180.

In the above embodiment, the glass seal portion 125 is disposed near the hole 121 in the single cell separator 120, but the glass seal portion 125 may be omitted.

In the above embodiment, the interconnector 190 includes a conductive coating layer 194, but the interconnector 190 does not necessarily have to include the coating layer 194. Also, in the above embodiment, the single cell 110 includes an intermediate layer 118, but the single cell 110 does not necessarily have to include the intermediate layer 118.

In the above embodiment, the unit cell 110 is an anode-supported unit cell, but it may be another type of unit cell, such as an electrolyte-supported or metal-supported unit cell. In an embodiment in which a metal-supported unit cell is used, the metal support corresponds to the unit cell separator in the claims, and the other layers supported by the metal support correspond to the unit cell in the claims.

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. In addition, the materials constituting each member in the above embodiment are merely examples, and each member may be composed of other materials.

In the above embodiment, the SOFC generates electricity by utilizing an electrochemical reaction between hydrogen contained in a fuel gas and oxygen contained in an oxidant gas. However, the technology disclosed in this specification can be applied to an electrolysis cell unit, which is a constituent unit of a solid oxide electrolysis cell (SOEC) that generates hydrogen by utilizing an electrolysis reaction of water, and an electrolysis cell stack having a plurality of electrolysis cell units. The configurations of the electrolysis cell unit and the electrolysis cell stack are publicly known, for example, as described in JP 2016-81813 A, and will not be described in detail here, but are generally similar to the configurations of the power generation unit 102 and the fuel cell stack 100 in the above embodiment. That is, the fuel cell stack 100 in the above embodiment may be read as an electrolysis cell stack, the power generation unit 102 as an electrolysis cell unit, and the single cell 110 as an electrolysis single cell. However, when the electrolysis cell stack is operated, a voltage is applied between the electrodes so that the air electrode 114 is positive (anode) and the fuel electrode 116 is negative (cathode), and water vapor is supplied as a raw material gas through a manifold. As a result, an electrolysis reaction of water occurs in each electrolysis cell unit, hydrogen gas is generated in the fuel chamber 176, and hydrogen is extracted to the outside of the electrolysis cell stack via the manifold. Even in an electrolysis cell stack of this configuration, if a configuration similar to that of the above embodiment is adopted, it is possible to suppress the occurrence of short circuits between the corners of the interconnector and the single cell separator, and to suppress damage to the electrolysis single cell due to the short circuit.

In the above embodiment, a solid oxide fuel cell (SOFC) has been described as an example, but the technology disclosed in this specification can also be applied to other types of fuel cells (or electrolytic cells), such as a polymer electrolyte fuel cell (PEFC), a phosphoric acid fuel cell (PAFC), and a molten carbonate fuel cell (MCFC).

22: Bolt 24: Nut 26: Insulating sheet 27: Gas passage member 28: Main body 29: Branching portion 32, 34: Hole 41: Felt member 44: Conductive portion 45: Cover member facing portion 46: Interconnector facing portion 47: Connection portion 48: Connection member 49: Elastic portion 50: Cover member 58: Specific space 60: Cover separator 61: Hole 66: Inner portion 67: Outer portion 68: Connection portion 70: Upper terminal plate 71: Hole 78: Protrusion 80: Lower terminal plate 88: Protrusion 92: Insulating sheet 100: Fuel cell stack 102: Fuel cell power generation unit 103: Power generation block 104: Upper end plate 106: Lower end plate 108: Communication hole 110: Fuel cell unit cell 112: Electrolyte layer 114: Air electrode 116: Fuel electrode 118: Intermediate layer 120: Single cell separator 121: Hole 124: Joint portion 125: Glass seal portion 126: Inner portion 127: Outer portion 128: Connection portion 130: Air electrode side frame 131: Hole 132: Oxidant gas supply passage 133: Oxidant gas discharge passage 134: Air electrode side current collecting portion 140: Fuel electrode side frame 141: Hole 142: Fuel gas supply passage 143: Fuel gas discharge passage 144: Conductive portion 145: Electrode opposing portion 146: Interconnector opposing portion 147: Connection portion 148: Fuel electrode side current collecting member 149: Elastic portion 150: Flat plate portion 161: Oxidant gas supply manifold 162: Oxidant gas discharge manifold 166: Air chamber 171: Fuel gas supply manifold 172: Fuel gas exhaust manifold 176: Fuel chamber 180: Interconnector separator 181: Hole 186: Inner part 187: Outer part 188: Connection part 190: Interconnector 194: Coating layer 196: Conductive bonding material CP: Corner FG: Fuel gas FOG: Fuel off-gas GCP: General corner OG: Oxidizer gas OOG: Oxidizer off-gas SCP: Specific corner

Claims (5)

an electrochemical reaction unit cell including an electrolyte layer, and an air electrode and a fuel electrode facing each other in a first direction with the electrolyte layer interposed therebetween;
a conductive single cell separator that is joined to the electrochemical reaction single cell and divides a gas chamber facing the air electrode from a gas chamber facing the fuel electrode;
a conductive interconnector that is disposed so as to face a specific electrode, which is one of the fuel electrode and the air electrode, in the first direction and is electrically connected to the specific electrode;
In an electrochemical reaction unit comprising:
In at least one specific cross section along the first direction, the interconnector has a corner portion that is substantially perpendicular to the first direction and connects a surface at least a portion of which faces the specific electrode with a surface facing an outer periphery, the corner portion satisfying the following conditions: (1) the corner portion faces the single cell separator in the first direction; and (2) the corner portion does not include a portion that is bent at an angle of 90 degrees or less.
An electrochemical reaction unit characterized by: The electrochemical reaction unit according to claim 1, further comprising:
an insulating member disposed between the unit cell separator and a part of a corner portion connecting a surface of the interconnector facing the specific electrode and a surface facing an outer periphery in a gas chamber facing the specific electrode,
the specific corner portion, which is another part of the corner portion , faces the unit cell separator in the first direction without the insulating member therebetween.
An electrochemical reaction unit characterized by: The electrochemical reaction unit according to claim 1 or 2, further comprising:
a conductive separator for the interconnector that is joined to the interconnector and that defines a gas chamber facing the specific electrode;
The specific corner portion is a corner portion located on an outer periphery of the interconnector when viewed in the first direction.
An electrochemical reaction unit characterized by: In the electrochemical reaction unit according to any one of claims 1 to 3,
When viewed in the first direction, a contour line of the corner portion of the interconnector does not include a portion that is bent at an angle of 90 degrees or less.
An electrochemical reaction unit characterized by: In an electrochemical reaction cell stack including a plurality of electrochemical reaction units arranged in the first direction,
At least one of the plurality of electrochemical reaction units is the electrochemical reaction unit according to any one of claims 1 to 4.
Electrochemical reaction cell stack comprising:

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