JP7159249B2 - Electrochemical reaction cell stack and IC-single cell composite - Google Patents

Description

The technology disclosed by this specification relates to an electrochemical reaction cell stack.

A solid oxide fuel cell (hereinafter referred to as “SOFC”) is known as one of fuel cells that generate power using an electrochemical reaction between hydrogen and oxygen. A fuel cell power generation unit (hereinafter referred to as "power generation unit"), which is a structural unit of SOFC, includes a fuel cell single cell (hereinafter referred to as "single cell"), a cell-side separator, and a frame member. A single cell includes an electrolyte layer, and an air electrode and a fuel electrode facing each other in a first direction with the electrolyte layer interposed therebetween. SOFCs are used in the form of fuel cell stacks arranged side by side in a predetermined direction (hereinafter referred to as "first direction").

The cell-side separator is formed with a separator through-hole that is a through-hole penetrating in the first direction. A portion of the cell-side separator surrounding the separator through-hole when viewed in the first direction is connected to the peripheral portion of the single cell. A frame through-hole is formed in the frame member so as to penetrate in the first direction. The frame through-hole constitutes an air chamber facing the air electrode and a fuel chamber facing the fuel electrode. A portion of the frame member surrounding the frame through-hole when viewed in the first direction is connected to the outer peripheral portion of the cell-side separator. The cell-side separator separates the air chamber and the fuel chamber.

As a conventional fuel cell stack, in a cross section parallel to the first direction in the fuel cell stack (hereinafter referred to as "specific cross section"), the cell-side separator has a first portion connected to the unit cell and a frame a second portion connected to the member; and a second portion connecting the first portion and the second portion and projecting in the first direction relative to both the first portion and the second portion. There is known a device in which the entire connecting portion has a curved shape (for example, Patent Literature 1). In this fuel cell stack, since the cell-side separators are provided with the connecting portions, the connecting portions of the cell-side separators will not move when a load is applied to the single cells due to the thermal cycle or the like during the power generation operation of the fuel cell stack. By bending in the direction of the load, the stress generated in the single cell can be relieved, and in turn, deformation and cracking of the single cell due to the stress generated in the single cell can be suppressed.

JP 2020-9744 A

In the conventional fuel cell stack described above, in a specific cross section (a cross section parallel to the first direction), the connecting portion of the cell-side separator has a curved shape as a whole. Therefore, in this fuel cell stack, for example, when the fuel cell stack is exposed to a thermal cycle, strain is likely to accumulate in the connecting portions of the cell-side separators, which may cause fatigue failure in the cell-side separators.

It should be noted that such a problem is solved by electrolysis having a plurality of electrolytic cell units, which are structural units of a solid oxide type electrolytic cell (hereinafter referred to as "SOEC") that generates hydrogen using the electrolysis reaction of water. This is also a common problem with cell stacks. In this specification, the fuel cell single cell and the electrolytic single cell are collectively referred to as the electrochemical reaction single cell, the power generation unit and the electrolytic cell unit are collectively referred to as the electrochemical reaction unit, and the fuel cell stack and the electrolytic cell are collectively referred to as the electrochemical reaction unit. The stack is collectively called an electrochemical reaction cell stack. Moreover, such a problem is not limited to SOFCs and SOECs, but is common to other types of electrochemical reaction stacks.

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

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

(1) The electrochemical reaction cell stack disclosed in this specification comprises a plurality of electrochemical reaction units arranged side by side in the first direction. The electrochemical reaction unit includes a single cell including an electrolyte layer, an air electrode and a fuel electrode facing each other in a first direction with the electrolyte layer interposed therebetween, and a first separator penetrating unit penetrating in the first direction. A hole is formed, and a portion surrounding the first separator through-hole when viewed in the first direction is connected to a peripheral edge portion of the single cell, and an air chamber facing the air electrode and the fuel electrode and a frame through-hole penetrating in the first direction to form the fuel chamber or the air chamber. a frame member having a portion surrounding the frame through-hole connected to the outer peripheral portion of the cell-side separator. In a first specific cross section, which is at least one cross section parallel to the first direction, in the electrochemical reaction cell stack, the cell-side separator is arranged in a second direction orthogonal to the first direction. a first straight portion located between the cell and the frame member and extending in the second direction; and a first straight portion located between the first straight portion and the frame member in the second direction. , a second straight portion extending in the second direction, and connecting the first straight portion and the second straight portion, wherein the first straight portion and the second straight portion and a first connecting portion that protrudes in the first direction with respect to both and has a first bottom, and satisfies the following formula (1).
L1/L2≤4.3 (1)
L1: length between the single cell and the frame member in the second direction L2: length of the first bottom in the second direction

In this electrochemical reaction cell stack, since the formula: L1/L2≦4.3 is satisfied, compared with the configuration that does not satisfy the formula: L1/L2≦4.3, the electrochemical reaction cell stack is Strain build-up in the first connection is reduced when exposed to thermal cycling. Therefore, according to the present electrochemical reaction cell stack, it is possible to suppress the occurrence of fatigue fracture in the cell-side separator due to the accumulation of strain in the first connecting portion.

(2) In the electrochemical reaction cell stack, in the first specific cross section, the boundary portion between the first linear portion and the first connecting portion and the first connecting portion of the cell-side separator A boundary portion between the portion and the second straight portion may be curved with a radius of curvature of 0.8 mm or more. According to the present electrochemical reaction cell stack, with such a configuration, each boundary portion (the boundary portion between the first linear portion and the first connecting portion, and the first connecting portion and the second straight portion) is bent, the strain is suppressed from accumulating at each of the above boundary portions, and strain is accumulated at the first connecting portion. It is possible to more effectively suppress the occurrence of fatigue fracture in the cell-side separator due to the above.

(3) In the electrochemical reaction cell stack according to claim 1 or claim 2, the electrochemical reaction unit is an interconnect member facing the single cell in the first direction. and a second separator through-hole penetrating in the first direction is formed, and a portion surrounding the second separator through-hole as viewed in the first direction is connected to the peripheral edge portion of the interconnector member. and an IC-side separator that separates an air chamber facing the air electrode and a fuel chamber facing the fuel electrode. In a second specific cross section that is at least one cross section parallel to the first direction in the electrochemical reaction cell stack, the IC-side separator is positioned between the single cell and the frame member in the second direction. a third linear portion positioned between and extending in the second direction; and a third linear portion positioned between the third linear portion and the frame member in the second direction and extending in the second direction. an extending fourth linear portion connecting the third linear portion and the fourth linear portion; and for both the third linear portion and the fourth linear portion, the and a second connecting portion that protrudes in the first direction and has a second bottom, and satisfies the following formula (2).
L3/L4≤4.3 (2)
L3: length between the single cell and the frame member in the second direction L4: length of the second bottom in the second direction

In this electrochemical reaction cell stack, since the formula: L3/L4≦4.3 is satisfied, compared with the configuration that does not satisfy the formula: L3/L4≦4.3, the electrochemical reaction cell stack is Strain build-up in the second link is reduced when subjected to thermal cycling. Therefore, according to the present electrochemical reaction cell stack, it is possible to suppress the occurrence of fatigue fracture in the IC-side separator due to the accumulation of strain in the second connecting portion.

(4) In the above electrochemical reaction cell stack, in the second specific cross section, in the IC side separator, a boundary portion between the third linear portion and the second connecting portion, and the second connecting portion A boundary portion between the portion and the fourth linear portion may be curved with a radius of curvature of 0.8 mm or more. According to the present electrochemical reaction cell stack, with such a configuration, each boundary portion (a boundary portion between the third linear portion and the second connecting portion, and the second connecting portion and the fourth straight portion) is bent, the strain is suppressed from accumulating at each of the above boundary portions, and strain is accumulated at the second connecting portion. It is possible to more effectively suppress the occurrence of fatigue fracture in the IC side separator due to the above.

(5) The IC-single cell composite disclosed in the present specification includes a single 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 cell side in which a first separator through hole penetrating in a first direction is formed, and a portion surrounding the first separator through hole as viewed in the first direction is connected to a peripheral edge portion of the unit cell a separator; and a frame member having a frame through-hole formed therethrough that penetrates in the first direction, and a portion surrounding the frame through-hole as viewed in the first direction is connected to an outer peripheral portion of the cell-side separator. , in a first specific cross section that is at least one cross section parallel to the first direction, the cell-side separator extends in a second direction orthogonal to the first direction a first straight portion located between the single cell and the frame member and extending in the second direction, and between the first straight portion and the frame member in the second direction a second linear portion extending in the second direction, connecting the first linear portion and the second linear portion, wherein the first linear portion and the second linear portion are connected to each other; and a first connecting portion projecting in the first direction with respect to both the linear portion of and having a first bottom, satisfying the following formula (1).
L1/L2≤4.3 (1)
L1: length between the single cell and the frame member in the second direction L2: length of the first bottom in the second direction

According to the present IC-single cell composite, effects similar to those obtained by the electrochemical reaction cell stack described in (1) above can be obtained.

(6) In the above IC-single cell composite, in the first specific cross section, in the cell-side separator, a boundary portion between the first linear portion and the first connecting portion, and the first A boundary portion between the connecting portion and the second straight portion may be curved with a radius of curvature of 0.8 mm or more. According to the present IC-single cell composite, the same effects as those obtained by the electrochemical reaction cell stack described in (2) above can be obtained.

(7) The above IC-single cell composite further includes an interconnector member facing the single cell in the first direction, and a second separator through-hole penetrating in the first direction. , an IC side separator having a portion surrounding the second separator through-hole as viewed in the first direction and connected to a peripheral edge portion of the interconnector member, and at least one separator parallel to the first direction. In a second specific cross section which is a cross section, the IC side separator is positioned between the single cell and the frame member in the second direction and has a third straight portion extending in the second direction. a fourth linear portion positioned between the third linear portion and the frame member in the second direction and extending in the second direction; the third linear portion and the third linear portion; 4, projecting in the first direction with respect to both the third straight portion and the fourth straight portion, and having a second bottom portion; , and satisfies the following formula (2).
L3/L4≤4.3 (2)
L3: length between the single cell and the frame member in the second direction L4: length of the second bottom in the second direction

According to the present IC-single cell composite, the same effects as those obtained by the electrochemical reaction cell stack described in (3) above can be obtained.

(8) In the above IC-single cell composite, in the second specific cross section, in the IC side separator, the boundary portion between the third linear portion and the second connecting portion and the second connecting portion A boundary portion between the connecting portion and the fourth linear portion may be curved with a radius of curvature of 0.8 mm or more. According to this IC-single cell composite, the same effects as those obtained by the electrochemical reaction cell stack described in (4) above can be obtained.

The technology disclosed in this specification can be implemented in various forms. For example, an electrochemical reaction cell stack ( fuel cell stack or electrolysis cell stack), manufacturing methods thereof, and the like.

1 is a perspective view showing an external configuration of a fuel cell stack 100 according to this embodiment; FIG. FIG. 2 is an explanatory view showing the XZ cross-sectional configuration of the fuel cell stack 100 at the position II-II in FIG. 1; FIG. 2 is an explanatory view showing the YZ cross-sectional configuration of the fuel cell stack 100 at the position III-III in FIG. 1; FIG. 3 is an explanatory diagram showing an XZ cross-sectional configuration of two power generation units 102 adjacent to each other at the same position as the cross section shown in FIG. 2 ; FIG. 4 is an explanatory diagram showing the YZ cross-sectional configuration of two power generation units 102 adjacent to each other at the same position as the cross section shown in FIG. 3 ; FIG. 5 is an explanatory view showing the XY cross-sectional configuration of the power generation unit 102 at the position VI-VI in FIG. 4; FIG. 5 is an explanatory view showing the XY cross-sectional configuration of the power generation unit 102 at the position of VII-VII in FIG. 4; 3 is an XZ sectional view showing detailed configurations of a cell-side separator 120 and an IC-side separator 180; FIG. FIG. 5 is an explanatory diagram showing performance evaluation results; FIG. 5 is an explanatory diagram showing performance evaluation results;

A. This embodiment:
A-1. Device 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, and FIG. 2 is a view of the fuel cell stack 100 at the position II-II in FIG. 1 (and FIGS. 6 and 7 described later). FIG. 3 is an explanatory diagram showing the XZ cross-sectional structure, and FIG. 3 is an explanatory diagram showing the YZ cross-sectional structure of the fuel cell stack 100 at the position III-III in FIG. 1 (and FIGS. 6 and 7 described later). Each figure shows mutually orthogonal XYZ axes for specifying directions. In this specification, for the sake of convenience, the positive Z-axis direction is referred to as the upward direction, and the negative Z-axis direction is referred to as the downward direction. may be installed. The same applies to FIG. 4 and subsequent figures. The vertical direction (Z-axis direction) corresponds to the first direction in the claims.

The fuel cell stack 100 includes a plurality of (seven in this embodiment) fuel cell power generation units (hereinafter referred to as “power generation units”) 102 and a pair of end plates 104 and 106 . The seven power generation units 102 are arranged side by side in a predetermined arrangement direction (vertical direction in this embodiment). A pair of end plates 104 and 106 are arranged so as to sandwich an aggregate composed of seven power generation units 102 from above and below.

A plurality of holes (eight in this embodiment) penetrating in the vertical direction are formed in the peripheral edge portion around the Z-axis of each layer (the power generating unit 102, the end plates 104 and 106) constituting the fuel cell stack 100. Corresponding holes formed in each layer vertically communicate with each other to form communicating holes 108 extending vertically from one end plate 104 to the other end plate 106 . In the following description, the holes formed in each layer of the fuel cell stack 100 to form the communication holes 108 may also be referred to as the communication holes 108 .

A bolt 22 extending in the vertical direction is inserted through each communication hole 108 , and the fuel cell stack 100 is fastened by the bolt 22 and nuts 24 fitted on both sides of the bolt 22 . 2 and 3, between the nut 24 fitted on one side (upper side) of the bolt 22 and the upper surface of the end plate 104 constituting the upper end of the fuel cell stack 100, and between the bolt An insulating sheet 26 is interposed between the nut 24 fitted to the other side (lower side) of the fuel cell stack 22 and the lower surface of the end plate 106 forming the lower end of the fuel cell stack 100 . However, at a location where a gas passage member 27, which will be described later, is provided, between the nut 24 and the surface of the end plate 106, the insulating sheets disposed above and below the gas passage member 27 and the gas passage member 27, respectively. 26 intervenes. The insulating sheet 26 is composed of, for example, a mica sheet, a ceramic fiber sheet, a ceramic powder sheet, a glass sheet, a glass-ceramic composite, or the like.

The outer diameter of the shaft portion of each bolt 22 is smaller than the inner diameter of each communication hole 108 . Therefore, a space is secured between the outer peripheral surface of the shaft portion of each bolt 22 and the inner peripheral surface of each communication hole 108 . As shown in FIGS. 1 and 2, the fuel cell stack 100 is located near the midpoint of one side of the outer circumference of the fuel cell stack 100 around the Z-axis (the side on the positive side of the X-axis among the two sides parallel to the Y-axis). The space formed by the bolt 22 (bolt 22A) and the communication hole 108 through which the bolt 22A is inserted is supplied with the oxidant gas OG from the outside of the fuel cell stack 100, and the oxidant gas OG is used for each power generation. Functioning as an oxidant gas introduction manifold 161, which is a gas flow path for supplying to the unit 102, and the midpoint of the side opposite to the side (the side on the negative side of the X-axis among the two sides parallel to the Y-axis) A space formed by the bolt 22 (bolt 22B) located nearby and the communication hole 108 through which the bolt 22B is inserted is the oxidant offgas OOG, which is the gas discharged from the air chamber 166 of each power generation unit 102. It functions as an oxidant gas discharge manifold 162 that discharges to the outside of the fuel cell stack 100 . Incidentally, in the present embodiment, air is used as the oxidant gas OG. Further, in this embodiment, a blower (not shown) is used to introduce the oxidizing gas OG to the oxidizing gas introduction manifold 161 . In addition, before the oxidant gas OG is introduced into the oxidant gas introduction manifold 161, heat exchange occurs (for example, when the oxidant offgas OOG and the fuel offgas FOG discharged from the fuel cell stack 100 are burned). The oxidant gas OG may be preheated using heat exchange with heat.

As shown in FIGS. 1 and 3, the fuel cell stack 100 is positioned near the midpoint of one side of the outer circumference of the fuel cell stack 100 around the Z-axis (the side on the Y-axis positive direction side of the two sides parallel to the X-axis). Fuel gas FG is introduced from outside the fuel cell stack 100 into a space formed by the bolt 22 (bolt 22D) and the communication hole 108 through which the bolt 22D is inserted. The bolt 22 (the bolt 22E) and the communication hole 108 through which the bolt 22E is inserted discharges the fuel offgas FOG, which is the gas discharged from the fuel chamber 176 of each power generation unit 102, to the outside of the fuel cell stack 100. It functions as a fuel gas discharge manifold 172 that In this embodiment, hydrogen-rich gas obtained by reforming city gas, for example, is used as the fuel gas FG.

Four gas passage members 27 are provided in the fuel cell stack 100 . Each gas passage member 27 has a hollow tubular body portion 28 and a hollow tubular branch portion 29 branched from a side surface of the main body portion 28 . A hole in the branch portion 29 communicates with a hole in the main body portion 28 . A gas pipe (not shown) is connected to the branch portion 29 of each gas passage member 27 . Further, as shown in FIG. 2, the hole of the body portion 28 of the gas passage member 27 arranged at the position of the bolt 22A forming the oxidant gas introduction manifold 161 communicates with the oxidant gas introduction manifold 161. A hole in the body portion 28 of the gas passage member 27 arranged at the position of the bolt 22B forming the oxidant gas discharge manifold 162 communicates with the oxidant gas discharge manifold 162 . Further, as shown in FIG. 3, the hole of the body portion 28 of the gas passage member 27 arranged at the position of the bolt 22D forming the fuel gas introduction manifold 171 communicates with the fuel gas introduction manifold 171, and the fuel gas A hole in the body portion 28 of the gas passage member 27 arranged at the position of the bolt 22E forming the discharge manifold 172 communicates with the fuel gas discharge manifold 172 .

(Configuration of end plates 104, 106)
The pair of end plates 104 and 106 are substantially rectangular plate-shaped conductive members, and are made of, for example, stainless steel. One end plate 104 is arranged above the uppermost power generating unit 102 and the other end plate 106 is arranged below the lowermost power generating unit 102 . A pair of end plates 104 and 106 sandwich a plurality of power generation units 102 in a pressed state. The upper end plate 104 functions as the positive side output terminal of the fuel cell stack 100 , and the lower end plate 106 functions as the negative side output terminal of the fuel cell stack 100 .

(Configuration of power generation unit 102)
4 is an explanatory diagram showing the XZ cross-sectional configuration of two power generation units 102 adjacent to each other at the same position as the cross section shown in FIG. 2, and FIG. FIG. 3 is an explanatory diagram showing a YZ cross-sectional configuration of two power generation units 102; 6 is an explanatory diagram showing the XY cross-sectional configuration of the power generation unit 102 at the position VI-VI in FIG. 4, and FIG. 7 is the XY cross-sectional configuration of the power generation unit 102 at the position VII-VII in FIG. It is an explanatory diagram showing.

As shown in FIGS. 4 and 5, the power generation unit 102 includes a single cell 110, a cell-side separator 120, an IC-side separator 180, an air electrode-side frame member 130, an air electrode-side current collector 134, a fuel It comprises a pole-side frame member 140 , an anode-side current collector 144 , and a pair of interconnector members 150 . The cell-side separator 120, the IC-side separator 180, the air electrode-side frame member 130, and the fuel electrode-side frame member 140 have peripheral edges around the Z-axis formed with holes corresponding to the communication holes 108 through which the bolts 22 are inserted. It is Note that the single cell 110, the cell-side separator 120, the IC-side separator 180, the air electrode-side current collector 134, the fuel electrode-side frame member 140, the fuel electrode-side current collector 144, and the interface in the present embodiment. The composite including the connector member 150 corresponds to the IC-single cell composite in the scope of claims, and the fuel electrode side frame member 140 corresponds to the frame member in the scope of claims.

The interconnector member 150 is a substantially rectangular plate-shaped conductive member, and is made of, for example, ferritic stainless steel. The interconnector member 150 ensures electrical continuity between the power generating units 102 and prevents mixing of reaction gases between the power generating units 102 . In this embodiment, when two power generation units 102 are arranged adjacent to each other, one interconnector member 150 is shared by the two adjacent power generation units 102 . That is, the upper interconnector member 150 in one power generation unit 102 is the same member as the lower interconnector member 150 in another power generation unit 102 adjacent to the upper side of the power generation unit 102 . In addition, since the fuel cell stack 100 has a pair of end plates 104 and 106, the power generation unit 102 located at the top in the fuel cell stack 100 does not have the upper interconnector member 150, and the bottom The generating unit 102 does not have a lower interconnect member 150 (see FIGS. 2 and 3). The interconnector member 150 forming the power generation unit 102 vertically faces the single cell 110 forming the power generation unit 102 .

The single cell 110 includes an electrolyte layer 112, and an air electrode (cathode) 114 and a fuel electrode (anode) 116 facing each other in the vertical direction (the direction in which the power generating units 102 are arranged) with the electrolyte layer 112 interposed therebetween. The unit cell 110 of this embodiment is a flat plate type unit cell, and is a fuel electrode supporting type unit cell in which the electrolyte layer 112 and the air electrode 114 are supported by the fuel electrode 116 .

The electrolyte layer 112 is a substantially rectangular plate-shaped member when viewed from the top and bottom, and is a dense layer. The electrolyte layer 112 is formed of a solid oxide such as YSZ (yttria-stabilized zirconia), ScSZ (scandia-stabilized zirconia), SDC (samarium-doped ceria), GDC (gadolinium-doped ceria), perovskite-type oxide, or the like. there is Thus, the single cell 110 of this embodiment is a solid oxide fuel cell (SOFC) using a solid oxide as an electrolyte. The air electrode 114 is a substantially rectangular plate-shaped member smaller than the electrolyte layer 112 when viewed from the top and bottom, and is a porous layer. The air electrode 114 is made of, for example, a perovskite oxide (eg, LSCF (lanthanum strontium cobalt iron oxide), LSM (lanthanum strontium manganese oxide), LNF (lanthanum nickel iron)). The fuel electrode 116 is a substantially rectangular plate-shaped member having substantially the same size as the electrolyte layer 112 when viewed from above, and is a porous layer. The fuel electrode 116 is made of, for example, a cermet made of Ni and oxide ion conductive ceramic particles (eg, YSZ).

The cell-side separator 120 is a frame-shaped member in which a substantially rectangular first separator through-hole 121 penetrating in the vertical direction is formed near the center, and is made of a metal material such as stainless steel, for example. The cell-side separator 120 has a first through-hole surrounding portion 122 (see FIG. 8) that surrounds the first separator through-hole 121 in the cell-side separator 120 . Of the surfaces of the first through-hole surrounding portion 122, the surface on the downward side faces the peripheral portion of the surface of the electrolyte layer 112 constituting the unit cell 110 on the side (upper side) facing the air electrode 114. . The cell-side separator 120 is joined to the unit cell 110 (electrolyte layer 112) by a first joining portion 124 containing brazing material (for example, Ag brazing) arranged around the first through hole 122. FIG. Therefore, the first through-hole peripheral portion 122 is connected to the peripheral portion of the unit cell 110 . An air chamber 166 facing the air electrode 114 and a fuel chamber 176 facing the fuel electrode 116 are separated by the cell-side separator 120, and gas leakage from the air chamber 166 to the fuel chamber 176 at the periphery of the unit cell 110 is prevented. Suppressed.

A first glass seal portion 125 containing glass is arranged on the side of the air chamber 166 with respect to the first joint portion 124 . The first glass seal portion 125 is provided on both the surface of the first through-hole surrounding portion 122 of the cell-side separator 120 and the surface of the unit cell 110 (the electrolyte layer 112 constituting the unit cell 110 in this embodiment). formed to make contact. Gas leak (cross leak) between air chamber 166 and fuel chamber 176 is effectively suppressed by first glass seal portion 125 .

The IC side separator 180 is a frame-shaped member having a substantially rectangular second separator through-hole 181 penetrating in the vertical direction near the center, and is made of a metal material such as stainless steel, for example. The IC side separator 180 separates the fuel chamber 176 from the air chamber 166 facing the air electrode 114 of the other adjacent unit cell 110, and the air chamber 166 at the peripheral edge of the interconnector member 150 to the fuel chamber 176 is separated. Gas leakage is suppressed.

The IC-side separator 180 has a second through-hole surrounding portion 182 (see FIG. 8) that surrounds the second separator through-hole 181 in the IC-side separator 180 . The IC side separator 180 is welded to the upper surface of the peripheral portion of the interconnector member 150 on the lower surface of the second through-hole peripheral portion 182 . Therefore, of the IC-side separator 180 , a second through-hole peripheral portion 182 surrounding the second separator through-hole 181 in the vertical direction is connected to the peripheral portion of the interconnector member 150 . In this embodiment, the IC side separator 180 is joined by welding as described above, so that gas leak (cross leak) between the air chamber 166 and the fuel chamber 176 is more effectively suppressed.

As shown in FIGS. 4 to 6, the air electrode side frame member 130 is a frame-shaped member having a substantially rectangular air chamber hole 131 extending vertically through the vicinity of the center thereof. It is made of an insulator. The portion of the air electrode-side frame member 130 surrounding the air chamber hole 131 when viewed in the vertical direction is the outer peripheral portion of the surface of the cell-side separator 120 on the side (upper side) facing the air chamber 166 . , and the outer periphery of the surface of the IC side separator 180 facing the air chamber 166 (lower side). An air chamber 166 facing the air electrode 114 is configured by the air chamber hole 131 formed in the air electrode side frame member 130 . Also, the air electrode side frame member 130 electrically insulates between the pair of IC side separators 180 included in the power generation unit 102 . As a result, the pair of interconnector members 150 are electrically insulated. The air electrode side frame member 130 also includes an oxidizing gas supply communication channel 132 that communicates between the oxidizing gas introduction manifold 161 and the air chamber 166, and an oxidizing gas supply channel that communicates between the air chamber 166 and the oxidizing gas discharge manifold 162. A chemical gas discharge communication channel 133 is formed.

As shown in FIGS. 4, 5, and 7, the fuel electrode side frame member 140 is a frame-shaped member having a substantially rectangular fuel chamber hole 141 extending vertically through the vicinity of the center thereof. It is made of metal. The portion of the fuel electrode-side frame member 140 that surrounds the fuel chamber hole 141 in a vertical view is the outer peripheral portion of the surface of the cell-side separator 120 facing the fuel chamber 176 (lower side). and the outer peripheral portion of the surface of the IC side separator 180 on the side (upper side) facing the fuel chamber 176 . A fuel chamber 176 facing the fuel electrode 116 is configured by the fuel chamber hole 141 formed in the fuel electrode-side frame member 140 . The fuel electrode-side frame member 140 also includes a fuel gas supply communication passage 142 that communicates the fuel gas introduction manifold 171 and the fuel chamber 176, and a fuel gas discharge communication passage that communicates the fuel chamber 176 and the fuel gas discharge manifold 172. A flow path 143 is formed.

As shown in FIGS. 4 and 5, the cathode-side current collector 134 is arranged within the air chamber 166 . The air electrode-side current collector 134 is composed of a plurality of substantially quadrangular prism-shaped current collector elements 135, and is made of, for example, ferritic stainless steel. The air electrode-side current collector 134 is in contact with the surface of the air electrode 114 opposite to the electrolyte layer 112 and the surface of the interconnect member 150 facing the air electrode 114 . However, as described above, the uppermost power generation unit 102 in the fuel cell stack 100 does not have the upper interconnector member 150, so the air electrode side current collector 134 in the power generation unit 102 is located at the upper end. It is in contact with plate 104 . Since the air electrode side current collector 134 has such a configuration, it electrically connects the air electrode 114 and the interconnector member 150 (or the end plate 104). The air electrode side current collector 134 may be covered with a conductive coating, and a conductive bonding layer is provided between the air electrode 114 and the air electrode side current collector 134 to bond the two. may intervene. Also, the air electrode side current collector 134 may be configured as a member integrated with the interconnector member 150 .

As shown in FIGS. 4 and 5, the fuel electrode side current collector 144 is arranged within the fuel chamber 176 . The fuel electrode-side current collector 144 includes an interconnector-facing portion 146, an electrode-facing portion 145, and a connecting portion 147 that connects the electrode-facing portion 145 and the interconnector-facing portion 146. For example, nickel or a nickel alloy is used. , stainless steel or the like. The electrode facing portion 145 is in contact with the surface of the fuel electrode 116 opposite to the side facing the electrolyte layer 112 , and the interconnector facing portion 146 is in contact with the surface of the interconnect member 150 facing the fuel electrode 116 . are in contact with However, as described above, since the lowermost power generation unit 102 in the fuel cell stack 100 does not have the lower interconnector member 150, the interconnector facing portion 146 of the power generation unit 102 is the lower end. It is in contact with plate 106 . Fuel electrode-side current collector 144 having such a configuration electrically connects fuel electrode 116 and interconnector member 150 (or end plate 106). A spacer 149 made of mica, for example, is arranged between the electrode facing portion 145 and the interconnector facing portion 146 . Therefore, the fuel electrode side current collector 144 follows the deformation of the power generation unit 102 due to temperature cycles and reaction gas pressure fluctuations, and the fuel electrode 116 and the interconnector member 150 (or the end plate 106 ) through the fuel electrode side current collector 144. ) is well maintained.

A-2. Operation of fuel cell stack 100:
As shown in FIGS. 2 and 4, the oxidant gas OG is supplied through a gas pipe (not shown) connected to the branch portion 29 of the gas passage member 27 provided at the position of the oxidant gas introduction manifold 161. Then, the oxidizing gas OG is supplied to the oxidizing gas introduction manifold 161 through the branch portion 29 of the gas passage member 27 and the hole of the main body portion 28 , and the oxidizing gas OG is supplied from the oxidizing gas introduction manifold 161 to each power generation unit 102 . The agent gas is supplied to the air chamber 166 via the agent gas supply communication channel 132 . 3 and 5, the fuel gas FG is supplied through a gas pipe (not shown) connected to the branch portion 29 of the gas passage member 27 provided at the position of the fuel gas introduction manifold 171. Then, the fuel gas FG is supplied to the fuel gas introduction manifold 171 via the branch portion 29 of the gas passage member 27 and the hole of the main body portion 28, and the fuel gas supply communication of each power generation unit 102 from the fuel gas introduction manifold 171. It is supplied to the fuel chamber 176 via the flow path 142 .

When the oxidant gas OG is supplied to the air chamber 166 of each power generation unit 102 and the fuel gas FG is supplied to the fuel chamber 176, the oxygen contained in the oxidant gas OG and the hydrogen contained in the fuel gas FG in the single cell 110 Electricity is generated by an electrochemical reaction with This power generation reaction is an exothermic reaction. In each power generation unit 102, the air electrode 114 of the single cell 110 is electrically connected to one interconnector member 150 through the air electrode side current collector 134, and the fuel electrode 116 is electrically connected through the fuel electrode side current collector 144. are electrically connected to the other interconnector member 150 . Also, the plurality of power generation units 102 included in the fuel cell stack 100 are electrically connected in series. Therefore, the electrical energy generated in each power generation unit 102 is taken out from the end plates 104 and 106 that function as output terminals of the fuel cell stack 100 . Since the SOFC generates power at a relatively high temperature (for example, 700° C. to 1000° C.), the fuel cell stack 100 is heated by the heater ( (not shown).

The oxidant off-gas OOG discharged from the air chamber 166 of each power generation unit 102 is discharged to the oxidant gas discharge manifold 162 through the oxidant gas discharge communication channel 133 as shown in FIGS. A gas pipe (not shown) connected to the branch portion 29 through holes in the body portion 28 and the branch portion 29 of the gas passage member 27 provided at the position of the oxidizing gas discharge manifold 162 leads to the fuel cell stack. 100 is discharged to the outside. Further, as shown in FIGS. 3 and 5, the fuel offgas 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 passage 143, and further fuel The fuel cell stack 100 is exposed to the outside of the fuel cell stack 100 via a gas pipe (not shown) connected to the branch portion 29 through the holes of the main body portion 28 and the branch portion 29 of the gas passage member 27 provided at the position of the gas discharge manifold 172 . discharged to

In the following description, the combination of the air electrode side frame member 130 and the fuel electrode side frame member 140 is referred to as the "frame member 200", and the combination of the air chamber hole 131 and the fuel chamber hole 141 is referred to as the "frame through hole". A portion of the frame member 200 that surrounds the frame through-hole 201 in a vertical view is called a “frame through-hole surrounding portion 202” (see FIG. 8). Note that the frame member 200 corresponds to the frame member in the claims.

As described above, the portion of the air electrode-side frame member 130 that surrounds the air chamber hole 131 in a vertical view is the outer circumference of the surface of the cell-side separator 120 that faces the air chamber 166 . and the outer peripheral portion of the surface of the surface of the IC side separator 180 facing the air chamber 166 . In addition, the portion of the fuel electrode-side frame member 140 surrounding the fuel chamber hole 141 in the vertical direction is the outer peripheral portion of the surface of the surface of the cell-side separator 120 facing the fuel chamber 176, It is in contact with the outer peripheral portion of the surface of the IC side separator 180 facing the fuel chamber 176 . As is clear from the above, of the frame member 200 , the frame through-hole peripheral portion 202 that surrounds the frame through-hole 201 in a vertical view is connected to the outer peripheral portion of the cell-side separator 120 .

A-3. Detailed Configuration of Cell Side Separator 120 and IC Side Separator 180:
FIG. 8 is an explanatory diagram showing detailed configurations of the cell-side separator 120 and the IC-side separator 180. As shown in FIG. FIG. 8 shows an enlarged view of the configuration of the Px portion of FIG. The cross section of the fuel cell stack 100 shown in FIGS. 4 and 8 is a cross section parallel to the vertical direction and passing through the center point PO (see FIG. 6 or 7) of the single cell 110 when viewed from the vertical direction. The cross section of the fuel cell stack 100 shown in FIG. 4 corresponds to the first specific cross section and the second specific cross section in the claims.

In the fuel cell stack 100 of the present embodiment, the cell-side separator 120 and the IC-side separator 180 have the following configurations in any cross section passing through the center point PO of the unit cell 110 in a vertical view and parallel to the vertical direction. is adopted. The cross-sections shown in FIGS. 4 and 8 are examples of arbitrary cross-sections passing through the center point PO of the unit cell 110 in a vertical view and parallel to the vertical direction.

A-3-1. Detailed configuration of the cell-side separator 120:

As shown in FIG. 8 , the cell-side separator 120 has a first linear portion 126 , a second linear portion 127 and a first connecting portion 128 . A thickness (plate thickness, hereinafter the same) T1 of the cell-side separator 120 is 0.3 mm or less, for example, about 0.1 mm. Note that the first linear portion 126 includes the first through-hole peripheral portion 122 .

The first linear portion 126 is positioned between the unit cell 110 and the frame member 200 in the X-axis direction, which is a direction orthogonal to the vertical direction, and extends linearly in the X-axis direction. The X-axis direction of the first linear portion 126 corresponds to the second direction in the claims.

The second straight portion 127 is positioned between the first straight portion 126 and the frame member 200 in the X-axis direction and extends linearly in the X-axis direction.

The first connecting portion 128 connects the first straight portion 126 and the second straight portion 127 and protrudes downward from both the first straight portion 126 and the second straight portion 127. ing. The first connecting portion 128 has a curved shape protruding downward from the positions of the first straight portion 126 and the second straight portion 127 . That is, the upper side of the first connecting portion 128 is a recess. Note that the length by which the first connecting portion 128 protrudes with respect to the first straight portion 126 or the second straight portion 127 (hereinafter referred to as "first connecting portion depth") H1 is 0.5 mm. It is 2 mm or more, for example 1 mm. The first connecting portion 128 is formed by, for example, press working.

By providing the cell-side separator 120 with the first connecting portion 128 projecting downward from both the first straight portion 126 and the second straight portion 127 as described above, the power generation of the fuel cell stack 100 is When a load is applied to the single cell 110 due to a thermal cycle or the like during operation, the first connecting portion 128 bends in the direction of the load, thereby relieving the stress generated in the single cell 110. Deformation and cracking of the single cell 110 due to stress generated in the cell 110 can be suppressed.

The detailed configuration of the first connecting portion 128 is as follows.

The first connecting portion 128 includes a first bottom portion 128a located at an end of the first connecting portion 128 in the projecting direction (downward in this embodiment), the first bottom portion 128a, and the first straight portion 126. It has a first connecting portion 128 b that connects, and a second connecting portion 128 c that connects the first bottom portion 128 a and the second linear portion 127 . The first bottom portion 128 a is located below both the first straight portion 126 and the second straight portion 127 .

Regarding the first bottom portion 128a, the fuel cell stack 100 satisfies the following equation (1).
L1/L2≤4.3 (1)
L1: Length between single cell 110 and frame member 200 in X-axis direction L2: Length of first bottom portion 128a in X-axis direction

The "length of the first bottom portion 128a in the X-axis direction (the direction perpendicular to the vertical direction)" mentioned above refers to a boundary portion B11 (first A boundary portion B11 between the bottom portion 128a and the first connection portion 128b) and a portion connecting the boundary portion B12 (a boundary portion B12 between the first bottom portion 128a and the second connection portion 128c) (see R in FIG. 8) means the length in the X-axis direction (see L2 in FIG. 8).

The value of L1 is 10 (mm) or more and 15 (mm) or less. The value of L2 is 3 (mm) or more and 8 (mm) mm. For example, the value of L1 is 13 (mm) and the value of L2 is 6 (mm), in which case the value of L1/L2 is 2.2.

Further, in the cell-side separator 120, the boundary portion B1 between the first linear portion 126 and the first connecting portion 128 becomes lower as it is positioned in the negative direction of the X-axis when viewed in the Y-axis direction, and has a radius of curvature. It is curved to be 0.8 mm or more. Here, in the cell-side separator 120, “a boundary portion γ between a certain portion α and a certain portion β is curved with a radius of curvature of 0.8 mm or more” means that the surface of the cell-side separator 120 (At least one of the surface facing the air chamber 166 and the surface facing the fuel chamber 176), the boundary point γ0 between the portion α and the portion β The portion between the point γ1 is a curve with a radius of curvature of 0.8 mm or more, and is between the boundary point γ0 and the point γ2 which is 0.29 mm away from the boundary point γ0 on the opposite side of the point γ1. The part in between means a curve with a radius of curvature of 0.8 mm or more (the same applies hereinafter). Bp10 in FIG. 8 indicates a boundary point between the first linear portion 126 and the first connecting portion 128 on the surface of the cell-side separator 120, and Bp11 extends from the boundary point Bp10 to the unit cell 110 side. Bp12 indicates a point 0.29 mm apart, and Bp12 indicates a point 0.29 mm away from the boundary point Bp10 on the opposite side of the point Bp11.

Further, in the cell-side separator 120, the boundary portion B2 between the first connecting portion 128 and the second straight portion 127 becomes lower as it is positioned in the positive direction of the X-axis when viewed in the Y-axis direction, and has a radius of curvature. It is curved to be 0.8 mm or more.

In addition, in the first connecting portion 128 of the cell-side separator 120, the boundary portion B11 between the first bottom portion 128a and the first connecting portion 128b becomes higher as it is positioned in the positive direction of the X-axis when viewed in the Y-axis direction. and is curved so that the radius of curvature is 0.8 mm or more.

In addition, in the first connecting portion 128 of the cell-side separator 120, the boundary portion B12 between the first bottom portion 128a and the second connecting portion 128c becomes higher as it is positioned in the negative direction of the X-axis when viewed in the Y-axis direction. and is curved so that the radius of curvature is 0.8 mm or more.

In addition, the first straight portion 126, the second straight portion 127, and the first connecting portion 128 are formed so as to surround the first separator through-hole 121 when viewed from above (FIG. 6). reference). The second linear portion 127 is located closer to the outer periphery of the cell-side separator 120 than the first linear portion 126 when viewed in the vertical direction.

A-3-2. Detailed configuration of the IC side separator 180:
As shown in FIG. 8, the IC side separator 180 includes a third linear portion 186, a fourth linear portion 187, and a second connecting portion 188. As shown in FIG. The detailed configuration of the IC-side separator 180 is basically the same as the detailed configuration of the cell-side separator 120 described above. Therefore, basically, the "cell-side separator 120" in the detailed configuration of the cell-side separator 120 described above should be replaced with the "IC-side separator 180", and the "first straight line portion 126" should be replaced with the "third straight line portion 186". , "the second straight portion 127" should be replaced with "the fourth straight portion 187", and "the first connecting portion 128" should be replaced with the "second connecting portion 188". Further, "first through-hole surrounding portion 122" is read as "second through-hole surrounding portion 182", "first connecting portion depth H1" is read as "second connecting portion depth H2", The “first bottom portion 128a” should be read as “second bottom portion 188a”. Therefore, the detailed configuration of the IC side separator 180 will basically be omitted, and only the characteristic configuration will be described below.

The second connecting portion 188 connects the third linear portion 186 and the fourth linear portion 187 and protrudes downward from both the third linear portion 186 and the fourth linear portion 187. ing. The second connecting portion 188 has a curved shape protruding downward from the positions of the third straight portion 186 and the fourth straight portion 187 . That is, the upper side of the second connecting portion 188 is a recess.

The third straight portion 186 includes a second bottom portion 188a located at the end of the second connecting portion 188 in the projecting direction (downward in this embodiment), the second bottom portion 188a, and the third straight portion 186. It has a third connection portion 188 b for connection and a fourth connection portion 188 c for connection between the second bottom portion 188 a and the fourth linear portion 187 . The second bottom portion 188a is located below both the third straight portion 186 and the fourth straight portion 187. As shown in FIG.

Regarding the second bottom portion 188a, the fuel cell stack 100 satisfies the following equation (2).
L3/L4≤4.3 (2)
L3: Length between single cell 110 and frame member 200 in X-axis direction L4: Length of second bottom portion 188a in X-axis direction

The above-mentioned "length of the second bottom portion 188a in the X-axis direction" is defined by the same concept as the above-mentioned "length of the first bottom portion 128a in the X-axis direction". That is, of the second connecting portion 188 of the IC side separator 180, a boundary portion B13 (boundary portion B13 between the second bottom portion 188a and the third connecting portion 188b) and a boundary portion B14 (second bottom portion It means the length in the X-axis direction of the portion connecting the boundary portion B14) between 188a and the fourth connection portion 188c.

A boundary portion B3 between the third linear portion 186 and the second connecting portion 188 of the IC-side separator 180 is located downward in the negative direction of the X-axis when viewed in the Y-axis direction, and has a radius of curvature of 0.5. It is curved to be 8 mm or more.

In the IC side separator 180, the boundary portion B4 between the second connecting portion 188 and the fourth linear portion 187 becomes lower as it is positioned in the positive direction of the X-axis when viewed in the Y-axis direction, and has a radius of curvature of 0.5. It is curved to be 8 mm or more.

In addition, in the second connecting portion 188 of the IC side separator 180, the boundary portion B13 between the second bottom portion 188a and the third connecting portion 188b becomes higher as it is positioned in the positive direction of the X-axis when viewed in the Y-axis direction. and is curved so that the radius of curvature is 0.8 mm or more.

Also, in the second connecting portion 188 of the IC side separator 180, the boundary portion B14 between the second bottom portion 188a and the fourth connecting portion 188c becomes higher as it is positioned in the negative direction of the X axis when viewed in the Y axis direction. and is curved so that the radius of curvature is 0.8 mm or more.

A-4. Effect of this embodiment:
As described above, the fuel cell stack 100 of this embodiment includes a plurality of power generation units 102 arranged side by side in the vertical direction (Z-axis direction). The power generation unit 102 includes a single cell 110, a cell-side separator 120, and a frame member 200 (an air electrode-side frame member 130 and a fuel electrode-side frame member 140). The single cell 110 includes an electrolyte layer 112, and an air electrode 114 and a fuel electrode 116 that vertically face each other with the electrolyte layer 112 interposed therebetween. The cell-side separator 120 is formed with a first separator through-hole 121 penetrating vertically. In the cell-side separator 120 , a first through-hole surrounding portion 122 surrounding the first separator through-hole 121 in a vertical view is connected to the peripheral portion of the unit cell 110 . The cell-side separator 120 separates an air chamber 166 facing the air electrode 114 and a fuel chamber 176 facing the fuel electrode 116 . A frame through-hole 201 is formed through the frame member 200 in the vertical direction to define the fuel chamber 176 and the air chamber 166 . A frame through-hole peripheral portion 202 of the frame member 200 surrounding the frame through-hole 201 in a vertical view is connected to the outer peripheral portion of the cell-side separator 120 . In a cross-section parallel to the vertical direction of the fuel cell stack 100 (for example, the cross-sections shown in FIGS. 4 and 8; hereinafter referred to as “first specific cross-section”), the cell-side separator 120 has a first linear portion 126 and a , a second linear portion 127 and a first connecting portion 128 . The first straight portion 126 is positioned between the single cell 110 and the frame member 200 in a direction orthogonal to the vertical direction (hereinafter, the direction in the first specific cross section is referred to as the “first orthogonal direction”). , extending in a first orthogonal direction. The second straight portion 127 is located between the first straight portion 126 and the frame member 200 in the first orthogonal direction and extends in the first orthogonal direction. The first connecting portion 128 connects the first straight portion 126 and the second straight portion 127 and protrudes downward from both the first straight portion 126 and the second straight portion 127. ing. The first connecting portion 128 has a second bottom portion 188a. The fuel cell stack 100 satisfies the formula: L1/L2≤4.3. L1 is the length between the unit cell 110 and the frame member 200 in the first orthogonal direction, and L2 is the length of the second bottom portion 188a of the first connecting portion 128 in the first orthogonal direction. be.

In the fuel cell stack 100 of the present embodiment, the formula: L1/L2 ≤ 4.3 is satisfied. Strain buildup in the first link 128 is reduced when exposed to thermal cycling. Therefore, according to the fuel cell stack 100 of the present embodiment, it is possible to suppress the fatigue failure of the cell-side separator 120 due to the accumulation of strain in the first connecting portion 128 .

Note that the greater the thickness T1 of the cell-side separator 120 (the first linear portion 126, the second linear portion 127, and the first connecting portion 128), the greater the strain accumulated in the first connecting portion 128. There is Therefore, from the viewpoint of suppressing the fatigue fracture of the cell side separator 120 due to the accumulation of strain in the first connecting portion 128, the thickness T1 of the cell side separator 120 is set to 0.5 mm as described above. It is preferably 3 mm or less, more preferably 0.1 mm or less.

In addition, if the value of L1/L2 is greater than 4.3, the cell-side separator 120 undergoes inelastic deformation (plastic deformation or creep deformation) when the fuel cell stack 100 is exposed to thermal cycles. As a result, the gas flow path in the air chamber 166 or the fuel chamber 176 is obstructed or narrowed, so that the flow of gas may be obstructed and the pressure loss in the air chamber 166 or the fuel chamber 176 may increase. Therefore, in this configuration, the gas flow path in the air chamber 166 or the fuel chamber 176 is blocked or narrowed, which may cause problems such as deterioration of the power generation performance of the fuel cell stack 100 . On the other hand, in the fuel cell stack 100 of the present embodiment, as described above, the expression: L1/L2≦4.3 is satisfied, so that the cell-side separator 120 is suppressed from being inelasticly deformed. It is possible to suppress the occurrence of problems such as deterioration of the power generation performance of the battery stack 100 . Therefore, according to the fuel cell stack 100 of the present embodiment, good power generation performance can be achieved. Although the reason why the effect is obtained by the above configuration is not necessarily clear, by satisfying L1/L2≦4.3, the first connection is maintained when the fuel cell stack 100 is exposed to the thermal cycle as described above. It is presumed that this is because the accumulation of strain in the portion 128 is suppressed.

Further, in the fuel cell stack 100 of the present embodiment, in the first specific cross section, the boundary portion B1 between the first linear portion 126 and the first connecting portion 128 and the first connecting portion 128 of the cell-side separator 120 A boundary portion B2 between the portion 128 and the second straight portion 127 is curved with a curvature radius of 0.8 mm or more.

According to the fuel cell stack 100 of the present embodiment, the boundary portions B1 and B2 are curved with a radius of curvature of 0.8 mm or more. As compared with the configuration in which the strain is accumulated in the boundary portions B1 and B2, the accumulation of strain in the first connecting portion 128 causes fatigue failure in the cell-side separator 120. can be suppressed more effectively.

In addition, in the fuel cell stack 100 of the present embodiment, the power generation unit 102 includes an interconnector member 150 vertically opposed to the single cell 110 and an IC side separator 180 . The IC side separator 180 is formed with a second separator through-hole 181 penetrating vertically. A second through-hole peripheral portion 182 of the IC-side separator 180 surrounding the second separator through-hole 181 in a vertical view is connected to the peripheral portion of the interconnector member 150 . The IC side separator 180 separates the air chamber 166 facing the air electrode 114 and the fuel chamber 176 facing the fuel electrode 116 . In a cross section parallel to the vertical direction of the fuel cell stack 100 (for example, cross sections shown in FIGS. 4 and 8; hereinafter referred to as “second specific cross section”), the IC side separator 180 has a third linear portion 186 and a , a fourth linear portion 187 and a second connecting portion 188 . The third straight portion 186 is located between the single cell 110 and the frame member 200 in a cross section parallel to the up-down direction in the second specific cross section (hereinafter referred to as "second orthogonal direction"). extending in the direction perpendicular to the The fourth straight portion 187 is positioned between the third straight portion 186 and the frame member 200 in the second orthogonal direction and extends in the second orthogonal direction. The second connecting portion 188 connects the third linear portion 186 and the fourth linear portion 187, and extends vertically with respect to both the third linear portion 186 and the fourth linear portion 187. Protruding. The second connecting portion 188 has a second bottom portion 188a. The fuel cell stack 100 satisfies the formula: L3/L4≤4.3. L3 is the length between the unit cell 110 and the frame member 200 in the second orthogonal direction, and L4 is the length of the second bottom portion 188a of the second connecting portion 188 in the second orthogonal direction. be.

In the fuel cell stack 100 of the present embodiment, the formula: L3/L4≦4.3 is satisfied, so compared with the configuration that does not satisfy the formula: L3/L4≦4.3, the fuel cell stack 100 is Strain buildup in the second link 188 is reduced when exposed to thermal cycling. Therefore, according to the fuel cell stack 100 of the present embodiment, it is possible to prevent the IC-side separator 180 from fatigue failure due to strain accumulation in the second connecting portion 188 .

As with the thickness T1 of the cell-side separator 120 described above, the larger the thickness T2 of the IC-side separator 180 (the third linear portion 186, the fourth linear portion 187, and the second connecting portion 188), the greater the thickness. The strain that accumulates in the second connecting portion 188 tends to increase. Therefore, from the viewpoint of suppressing the fatigue fracture of the IC side separator 180 due to the accumulation of strain in the second connecting portion 188, the thickness T2 of the IC side separator 180 is set to 0.5 mm as described above. It is preferably 3 mm or less, more preferably 0.1 mm or less.

Similar to the cell-side separator 120 inelastic deformation as described above, if the value of L3/L4 is greater than 4.3, when the fuel cell stack 100 is exposed to thermal cycling, the IC-side Inelastic deformation of the separator 180 blocks the gas flow path in the air chamber 166 or the fuel chamber 176, obstructing the flow of gas, thereby reducing the power generation performance of the fuel cell stack 100. may occur. On the other hand, in the fuel cell stack 100 of the present embodiment, since the formula: L3/L4≦4.3 is satisfied as described above, the inelastic deformation of the IC side separator 180 is suppressed, and the fuel Problems such as deterioration of the power generation performance of the battery stack 100 can be more effectively suppressed. Therefore, according to the fuel cell stack 100 of the present embodiment, power generation performance can be improved.

Further, in the fuel cell stack 100 of the present embodiment, in the second specific cross section, the boundary portion B3 between the third linear portion 186 and the second connecting portion 188 and the second connecting portion 188 of the cell-side separator 120 A boundary portion B4 between the portion 188 and the fourth straight portion 187 is curved with a curvature radius of 0.8 mm or more.

According to the fuel cell stack 100 of the present embodiment, the boundary portions B3 and B4 are curved with a radius of curvature of 0.8 mm or more. As compared with the configuration in which the strain is accumulated in the boundary portions B3 and B4, the accumulation of strain in the second connecting portion 188 causes fatigue failure in the IC side separator 180. can be suppressed more effectively.

A-5. Performance evaluation:
Next, performance evaluation of this embodiment will be described. A plurality of samples of the fuel cell stack 100 having different characteristics were subjected to simulation-based performance evaluation (performance evaluation regarding durability against fatigue fracture of the separator). 9 and 10 are explanatory diagrams showing performance evaluation results. In this performance evaluation, a fuel cell stack 100 including a plurality of single cells 110 (power generation units 102) was constructed, and the strain accumulated in the cell side separator 120 and the IC side separator 180 during power generation operation was measured.

FIG. 9 shows the evaluation results of durability against fatigue fracture of the cell-side separator 120 and the IC-side separator 180 . As shown in FIG. 9, six samples (samples S1 to S6) of the fuel cell stack 100 were used for this performance evaluation. Each sample has the same L1 value and a different L2 value, and thus a different L1/L2 value. FIG. 10 shows the results of a simulation for verifying the amount of increase in strain accumulated in the cell-side separator 120 and the IC-side separator 180 when power generation is performed under the operating conditions described above.

"Large" described in the "increase amount of strain (Δε)" column in FIG. ” indicates that the strain amount is small.

As a result of simulation for each sample, if the amount of increase in strain accumulated in the cell-side separator 120 and the IC-side separator 180 is equal to or greater than the criteria, the amount of strain accumulated in the cell-side separator 120 and the IC-side separator 180 is excessive. Therefore, it was determined that there was a high risk of fatigue fracture occurring in the cell-side separator 120 and the IC-side separator 180, and it was evaluated as "x (failed)". Also, if the amount of increase in strain accumulated in the cell-side separator 120 and the IC-side separator 180 is less than the criteria, the amount of strain accumulated in the cell-side separator 120 and the IC-side separator 180 will not be excessive. , the cell-side separator 120 and the IC-side separator 180 were judged to have a low risk of fatigue fracture, and were evaluated as "good (acceptable)".

As shown in FIG. 9, in samples S1 and S2, the amount of strain accumulated in the cell-side separator 120 and the IC-side separator 180 was "large", so they were evaluated as "x". On the other hand, in samples S3 to S6, since the amount of strain accumulated in the cell-side separator 120 and the IC-side separator 180 was "small", they were evaluated as "good". Here, in samples S1 and S2, the value of L1/L2 is greater than 4.3, while in samples S3 to S6, the value of L1/L2 is 4.3 or less. From the above results, in the configuration in which the value of L1/L2 is 4.3 or less, strain is accumulated in the cell side separator 120 and the IC side separator 180 compared to the configuration in which the value of L1/L2 is greater than 4.3. It was confirmed that it is possible to suppress the occurrence of fatigue fracture in the cell-side separator 120 and the IC-side separator 180 due to the accumulation of strain in the cell-side separator 120 and the IC-side separator 180. was done. As shown in FIG. 10, it was confirmed that the amount of strain accumulated in the cell-side separator 120 and the IC-side separator 180 tends to decrease as the value of L2 increases.

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

For example, in the fuel cell stack 100 of the above-described embodiment, the cell-side separator 120 and the IC-side separator 180 described above pass through the center point PO of the unit cell 110 when viewed in the vertical direction and are parallel to the vertical direction. The configuration of the cell-side separator 120 and the IC-side separator 180 described above can be seen only in any cross section passing through the center point PO of the unit cell 110 in the vertical direction and parallel to the vertical direction. may be adopted. Further, in the fuel cell stack 100 of the above embodiment, the configuration of the cell-side separator 120 described above and the configuration of the IC-side separator 180 described above may be employed in mutually different cross sections.

In addition, in the above-described embodiment (or modified example, the same applies hereinafter), the first connecting portion 128 is configured to protrude upward from both the first linear portion 126 and the second linear portion 127. may In this configuration as well, for the same reason as in the configuration in which the first connecting portion 128 protrudes downward, deformation and cracking of the single cell 110 due to the stress generated in the single cell 110 can be suppressed. Further, the second connecting portion 188 connects the third straight portion 186 and the fourth straight portion 187, and is downwardly connected to both the third straight portion 186 and the fourth straight portion 187. It may be a configuration that protrudes into. In this configuration as well, deformation and cracking of the single cell 110 due to the stress generated in the single cell 110 can be suppressed for the same reason as in the configuration in which the second connecting portion 188 protrudes downward.

Further, in the above embodiment, the air electrode side frame member 130 and the fuel electrode side frame member 140 that constitute the frame member 200 may be integrally formed.

Further, the frame member 200 may have the frame through-hole 201 constituting only one of the fuel chamber 176 and the air chamber 166 .

In the above embodiment, the number of power generation units 102 included in the fuel cell stack 100 is merely an example, and the number of power generation units 102 is appropriately determined according to the required output voltage of the fuel cell stack 100 and the like. Further, in the above embodiment, an intermediate layer may be arranged between the air electrode 114 and the electrolyte layer 112 . In addition, the materials forming each member in the above-described embodiment are merely examples, and each member may be formed of another material.

In the above embodiments, SOFCs that generate electricity by utilizing the electrochemical reaction between hydrogen contained in the fuel gas and oxygen contained in the oxidant gas are targeted, but the present invention utilizes the electrolysis reaction of water. The present invention is also applicable to an electrolytic cell unit, which is a structural unit of a solid oxide electrolytic cell (SOEC) that generates hydrogen by squeezing, and an electrolytic cell stack including a plurality of electrolytic cell units. The configuration of the electrolysis cell stack is known, for example, as described in Japanese Patent Application Laid-Open No. 2016-81813, so it will not be described in detail here. Configuration. That is, the fuel cell stack 100 in the above-described embodiment can be read as an electrolytic cell stack, the power generation unit 102 can be read as an electrolytic cell unit, and the single cell 110 can be read as an electrolytic single cell. However, during the operation of the electrolysis cell stack, a voltage is applied between the two electrodes so that the air electrode 114 is positive (anode) and the fuel electrode 116 is negative (cathode). Water vapor is supplied as a source gas. As a result, an electrolysis reaction of water occurs in each electrolysis cell unit, hydrogen gas is generated in the fuel chamber 176 , and the hydrogen is taken out of the electrolysis cell stack through the communication hole 108 . In the electrolysis cell unit and the electrolysis cell stack having such a configuration as well, if a configuration similar to that of the above-described embodiment is adopted, it is possible to suppress the occurrence of fatigue fracture in the cell-side separator 120 .

22: Bolt 22A: Bolt 22B: Bolt 22D: Bolt 22E: Bolt 24: Nut 26: Insulating sheet 27: Gas passage member 28: Body portion 29: Branch portion 100: Fuel cell stack 102: Power generation unit 104, 106: End plate 108: communication hole 110: single cell 112: electrolyte layer 114: air electrode 116: fuel electrode 120: cell-side separator 121: first separator through-hole 122: first through-hole surrounding portion 124: first joint portion 125 : first glass seal portion 126: first straight portion 127: second straight portion 128: first connecting portion 128a: first bottom portion 128b: first connecting portion 128c: second connecting portion 130: Air electrode side frame member 131: Air chamber hole 132: Oxidant gas supply communication channel 133: Oxidant gas discharge communication channel 134: Air electrode side current collector 135: Current collector element 140: Fuel electrode side frame member 141: Fuel chamber hole 142: Fuel gas supply communication channel 143: Fuel gas discharge communication channel 144: Fuel electrode side current collector 145: Electrode facing portion 146: Interconnector facing portion 147: Connecting portion 149: Spacer 150: Interconnector member 161: Oxidant gas introduction manifold 162: Oxidant gas discharge manifold 166: Air chamber 171: Fuel gas introduction manifold 172: Fuel gas discharge manifold 176: Fuel chamber 180: IC side separator 181: Second separator through hole 182: second through-hole surrounding portion 186: third straight portion 187: fourth straight portion 188: second connecting portion 188a: second bottom portion 188b: third connecting portion 188c: fourth connecting portion 200: Frame member 201: Frame through-hole 202: Surrounding portion of frame through-hole FG: Fuel gas FOG: Fuel off-gas OG: Oxidant gas OOG: Oxidant off-gas

Claims (8)

a single 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 first separator through hole penetrating in the first direction is formed, and a portion surrounding the first separator through hole when viewed in the first direction is connected to a peripheral edge portion of the unit cell, a cell-side separator that separates an air chamber facing the air electrode and a fuel chamber facing the fuel electrode;
A frame through hole penetrating in the first direction and forming at least one of the fuel chamber and the air chamber is formed, and a portion surrounding the frame through hole when viewed in the first direction is the cell side. a frame member connected to the outer periphery of the separator;
In an electrochemical reaction cell stack in which a plurality of electrochemical reaction units comprising are arranged side by side in the first direction,
In a first specific cross section that is at least one cross section parallel to the first direction,
The cell-side separator is
a first straight portion positioned between the unit cell and the frame member in a second direction orthogonal to the first direction and extending in the second direction;
a second straight portion located between the first straight portion and the frame member in the second direction and extending in the second direction;
connecting the first linear portion and the second linear portion, projecting in the first direction with respect to both the first linear portion and the second linear portion; a first connection having a bottom;
with
A boundary portion between the first linear portion and the first connecting portion and a boundary portion between the first connecting portion and the second linear portion are curved,
satisfying the following formula (1),
An electrochemical reaction cell stack characterized by:
2.2≦ L1/L2≦4.3 (1)
L1: length between the single cell and the frame member in the second direction L2: length of the first bottom in the second direction In the electrochemical reaction cell stack according to claim 1,
In the first specific cross section,
In the cell-side separator, the boundary portion between the first linear portion and the first connecting portion and the boundary portion between the first connecting portion and the second linear portion have a radius of curvature of 0.5 mm. It is curved to be 8 mm or more,
An electrochemical reaction cell stack characterized by: In the electrochemical reaction cell stack according to claim 1 or claim 2,
The electrochemical reaction unit is
an interconnector member facing the unit cell in the first direction;
A second separator through hole penetrating in the first direction is formed, and a portion surrounding the second separator through hole as viewed in the first direction is connected to a peripheral edge portion of the interconnector member. , an IC side separator that separates an air chamber facing the air electrode and a fuel chamber facing the fuel electrode;
with
In a second specific cross section that is at least one cross section parallel to the first direction,
The IC side separator is
a third straight portion positioned between the single cell and the frame member in the second direction and extending in the second direction;
a fourth straight portion positioned between the third straight portion and the frame member in the second direction and extending in the second direction;
connecting the third linear portion and the fourth linear portion, projecting in the first direction with respect to both the third linear portion and the fourth linear portion; a second connection having a bottom;
with
satisfying the following formula (2),
An electrochemical reaction cell stack characterized by:
L3/L4≤4.3 (2)
L3: length between the single cell and the frame member in the second direction L4: length of the second bottom in the second direction In the electrochemical reaction cell stack according to claim 3,
In the second specific cross section,
In the IC side separator, a boundary portion between the third linear portion and the second connecting portion, and a boundary portion between the second connecting portion and the fourth linear portion have a radius of curvature of 0.5 mm. It is curved to be 8 mm or more,
An electrochemical reaction cell stack characterized by: a single 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 cell in which a first separator through hole penetrating in the first direction is formed, and a portion surrounding the first separator through hole as viewed in the first direction is connected to a peripheral edge portion of the unit cell. a side separator;
a frame member having a frame through-hole that penetrates in the first direction, and a portion surrounding the frame through-hole as viewed in the first direction is connected to an outer peripheral portion of the cell-side separator;
In an IC-single cell composite comprising
In a first specific cross section that is at least one cross section parallel to the first direction,
The cell-side separator is
a first straight portion positioned between the unit cell and the frame member in a second direction orthogonal to the first direction and extending in the second direction;
a second straight portion located between the first straight portion and the frame member in the second direction and extending in the second direction;
connecting the first linear portion and the second linear portion, projecting in the first direction with respect to both the first linear portion and the second linear portion; a first connection having a bottom;
with
A boundary portion between the first linear portion and the first connecting portion and a boundary portion between the first connecting portion and the second linear portion are curved,
satisfying the following formula (1),
An IC-single cell composite, characterized in that:
2.2≦ L1/L2≦4.3 (1)
L1: length between the single cell and the frame member in the second direction L2: length of the first bottom in the second direction In the IC-single cell composite of claim 5,
In the first specific cross section,
In the cell-side separator, the boundary portion between the first linear portion and the first connecting portion and the boundary portion between the first connecting portion and the second linear portion have a radius of curvature of 0.5 mm. It is curved to be 8 mm or more,
An IC-single cell composite, characterized in that: In the IC-single cell complex according to claim 5 or claim 6,
moreover,
an interconnector member facing the unit cell in the first direction;
A second separator through hole penetrating in the first direction is formed, and a portion surrounding the second separator through hole when viewed in the first direction is connected to a peripheral edge portion of the interconnector member. an IC side separator;
with
In a second specific cross section that is at least one cross section parallel to the first direction,
The IC side separator is
a third straight portion positioned between the single cell and the frame member in the second direction and extending in the second direction;
a fourth straight portion positioned between the third straight portion and the frame member in the second direction and extending in the second direction;
connecting the third linear portion and the fourth linear portion, projecting in the first direction with respect to both the third linear portion and the fourth linear portion; a second connection having a bottom;
with
satisfying the following formula (2),
An IC-single cell composite, characterized in that:
L3/L4≤4.3 (2)
L3: length between the single cell and the frame member in the second direction L4: length of the second bottom in the second direction In the IC-single cell composite of claim 7,
In the second specific cross section,
In the IC side separator, a boundary portion between the third linear portion and the second connecting portion, and a boundary portion between the second connecting portion and the fourth linear portion have a radius of curvature of 0.5 mm. It is curved to be 8 mm or more,
An IC-single cell composite, characterized in that:

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