JP2022026469A - Electrochemical reaction cell stack and ic-single cell compound - Google Patents

Abstract

To suppress the occurence of a fatigue breakdown in an electrochemical reaction cell stack.SOLUTION: An electrochemical reaction cell stack comprises: a plurality of electrochemical reaction units arranged in parallel to a first direction. Each electrochemical reaction unit comprises: a single cell containing an air electrode and a fuel electrode, which are faced each other to the first direction; and a cell side separator connected to the single cell and separating an air chamber from a fuel chamber. In a cross section in parallel to the first direction in the electrochemical reaction cell stack, a cell side separator comprises: a first straight part and a second straight part, extended to a second direction orthogonal to the first direction; and a coupling part that couples the first straight part and the second straight part, projected to the first direction to both of the first straight part and the second straight part, and has a bottom part. The electrochemical reaction cell stack satisfies the formula of L1/L2≤4.3 (L1 is the length between the single cell and a frame member in the second direction, and L2 is the length of the bottom in the second direction).SELECTED DRAWING: Figure 8

Description

The techniques disclosed herein relate to electrochemical reaction cell stacks.

A solid oxide fuel cell (hereinafter referred to as "SOFC") is known as one of the fuel cells that generate power by utilizing an electrochemical reaction between hydrogen and oxygen. The fuel cell power generation unit (hereinafter referred to as “power generation unit”), which is a constituent unit of the SOFC, includes a fuel cell single cell (hereinafter referred to as “single cell”), a cell-side separator, and a frame member. The single cell includes an electrolyte layer and an air electrode and a fuel electrode facing each other in a first direction across the electrolyte layer. Further, the SOFC is used in the form of a fuel cell stack 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, which is a through hole penetrating in the first direction. The portion of the cell-side separator that surrounds the separator through hole in the first direction is connected to the peripheral edge of the single cell. The frame member is formed with a frame through hole penetrating in the first direction. The frame through hole constitutes an air chamber facing the air electrode and a fuel chamber facing the fuel electrode. The portion of the frame member that surrounds the frame through hole in the first directional view 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 is a first portion connected to a single cell and a frame. The second portion connected to the member, the first portion and the second portion are connected, and project in the first direction with respect to both the first portion and the second portion. It is known that the connecting portion is provided and the entire connecting portion has a curved shape (for example, Patent Document 1). In this fuel cell stack, the cell-side separator is provided with the above-mentioned connecting portion, so that when a load is applied to a single cell due to a thermal cycle or the like during power generation operation of the fuel cell stack, the cell-side separator connecting portion is concerned. By bending in the direction of the load, the stress generated in the single cell can be relaxed, and by extension, the deformation and cracking of the single cell due to the stress generated in the single cell can be suppressed.

Japanese Unexamined Patent Publication No. 2020-9744

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

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

This specification discloses a technique capable of solving the above-mentioned problems.

The techniques disclosed herein can be realized, for example, in the following forms.

(1) The electrochemical reaction cell stack disclosed in the present specification includes a plurality of electrochemical reaction units arranged side by side in the first direction. The electrochemical reaction unit is a single cell including an electrolyte layer, an air electrode and a fuel electrode facing each other in the first direction across the electrolyte layer, and a first separator penetrating through the first direction. A hole is formed, and a portion surrounding the first separator through hole in the first directional view is connected to the peripheral edge of the single cell, and the air chamber facing the air electrode and the fuel electrode A cell-side separator that separates the fuel chamber facing the fuel chamber and a frame through hole that penetrates in the first direction and constitutes the fuel chamber or the air chamber are formed, and the said in the first direction view. A frame member whose portion surrounding the frame through hole is connected to the outer peripheral portion of the cell-side separator is provided. In a first specific cross section of the electrochemical reaction cell stack, which is at least one cross section parallel to the first direction, the cell side separator is the single in a second direction orthogonal to the first direction. It is located between the cell and the frame member, the first straight line portion extending in the second direction, and between the first straight line portion and the frame member in the second direction. , The second straight line portion extending in the second direction, the first straight line portion, and the second straight line portion are connected, and the first straight line portion and the second straight line portion are connected. It is provided with a first connecting portion that protrudes in the first direction and has a first bottom portion with respect to both of the above, 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 the present electrochemical reaction cell stack, since the formula: L1 / L2 ≦ 4.3 is satisfied, the above-mentioned electrochemical reaction cell stack is compared with the configuration which does not satisfy the formula: L1 / L2 ≦ 4.3. The accumulation of strain in the first connecting portion when exposed to a thermal cycle is suppressed. Therefore, according to the present electrochemical reaction cell stack, it is possible to prevent fatigue fracture from occurring 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 straight line portion and the first connecting portion of the cell-side separator, and the first connecting portion. The boundary portion between the portion and the second straight portion may be curved so that the radius of curvature is 0.8 mm or more. According to the present electrochemical reaction cell stack, due to such a configuration, each of the above-mentioned boundary portions (the boundary portion between the first straight line portion and the first connecting portion, and the first connecting portion). Strain is suppressed from accumulating at each of the above-mentioned boundary portions, and thus strain is accumulated at the first connecting portion, as compared with the configuration in which the boundary portion between the surface and the second straight line portion is bent. 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, in the electrochemical reaction cell stack according to claim 1 or 2, the electrochemical reaction unit is an interconnector member facing the single 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 in the first direction is connected to the peripheral edge portion of the interconnector member. It is provided with 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 of the electrochemical reaction cell stack, which is at least one cross section parallel to the first direction, the IC-side separator comprises the single cell and the frame member in the second direction. It is located between the third straight line portion extending in the second direction, the third straight line portion in the second direction, and the frame member, and is located in the second direction. The extending fourth straight line portion, the third straight line portion, and the fourth straight line portion are connected to each other, and the third straight line portion and the fourth straight line portion are both connected to each other. A second connecting portion protruding in the first direction and having a second bottom portion may be provided, and the configuration may satisfy 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 the present electrochemical reaction cell stack, since the formula: L3 / L4 ≦ 4.3 is satisfied, the above-mentioned electrochemical reaction cell stack is compared with the configuration which does not satisfy the formula: L3 / L4 ≦ 4.3. The accumulation of strain in the second connecting portion when exposed to the thermal cycle is suppressed. Therefore, according to the present electrochemical reaction cell stack, it is possible to prevent fatigue fracture from occurring in the IC-side separator due to the accumulation of strain in the second connecting portion.

(4) In the electrochemical reaction cell stack, in the second specific cross section, of the IC side separator, the boundary portion between the third straight line portion and the second connecting portion, and the second connecting portion. The boundary portion between the portion and the fourth straight line portion may be curved so that the radius of curvature is 0.8 mm or more. According to the present electrochemical reaction cell stack, due to such a configuration, each of the above-mentioned boundary portions (the boundary portion between the third straight line portion and the second connecting portion, and the second connecting portion). Strain is suppressed from accumulating at each of the above-mentioned boundary portions, and thus strain is accumulated at the second connecting portion, as compared with the configuration in which the boundary portion between the above and the fourth straight line portion is bent. 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, an air electrode and a fuel electrode facing each other in a first direction across the electrolyte layer, and the above. A cell side in which a first separator through hole penetrating in the first direction is formed, and a portion surrounding the first separator through hole is connected to the peripheral edge portion of the single cell in the first direction view. A separator and a frame member through which a frame through hole penetrating in the first direction is formed, and a portion surrounding the frame through hole in the first direction is connected to an 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 an IC-single cell complex comprising, the cell side separator is a second direction orthogonal to the first direction. Between the single cell and the frame member in the first straight line portion extending in the second direction, and between the first straight line portion and the frame member in the second direction. The second straight line portion extending in the second direction, the first straight line portion, and the second straight line portion are connected to each other, and the first straight line portion and the second straight line portion are connected to each other. It is provided with a first connecting portion that protrudes in the first direction with respect to both of the straight portions and has a first bottom portion, and satisfies the following equation (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 complex, the same effect as that obtained by the electrochemical reaction cell stack described in (1) above can be obtained.

(6) In the IC-single cell complex, in the first specific cross section, the boundary portion between the first straight line portion and the first connecting portion of the cell-side separator, and the first one. The boundary portion between the connecting portion and the second straight line portion may be curved so that the radius of curvature is 0.8 mm or more. According to the present IC-single cell complex, the same effect as that obtained by the electrochemical reaction cell stack described in (2) above can be obtained.

(7) In the IC-single cell composite, an interconnector member facing the single cell in the first direction and a second separator through hole penetrating in the first direction are further formed. , An IC-side separator whose portion surrounding the second separator through hole in the first directional view is connected to the peripheral edge of the interconnector member, and at least one parallel to the first direction. In the second specific cross section, which is a cross section, the IC-side separator is located between the single cell and the frame member in the second direction, and is a third straight line portion extending in the second direction. A fourth straight line portion located between the third straight line portion and the frame member in the second direction and extending in the second direction, the third straight line portion, and the second straight line portion. A second connecting portion that connects the straight portions of 4 and protrudes in the first direction with respect to both the third straight portion and the fourth straight portion and has a second bottom portion. , And may be configured to satisfy the following equation (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 complex, the same effect as that obtained by the electrochemical reaction cell stack described in (3) above can be obtained.

(8) In the IC-single cell complex, in the second specific cross section, the boundary portion between the third straight line portion and the second connecting portion of the IC side separator, and the second The boundary portion between the connecting portion and the fourth straight line portion may be curved so that the radius of curvature is 0.8 mm or more. According to the present IC-single cell complex, the same effect as that obtained by the electrochemical reaction cell stack described in (4) above can be obtained.

The technique disclosed in the present specification can be realized in various forms, for example, an electrochemical reaction cell stack including a plurality of electrochemical reaction units (fuel cell power generation unit or electrolytic cell unit) (for example, an electrochemical reaction cell stack (fuel cell power generation unit or electrolytic cell unit). It can be realized in the form of a fuel cell stack or an electrolytic cell stack), a method for manufacturing them, and the like.

It is a perspective view which shows the appearance structure of the fuel cell stack 100 in this embodiment. It is explanatory drawing which shows the XZ cross-sectional structure of the fuel cell stack 100 at the position of II-II of FIG. It is explanatory drawing which shows the YZ cross-sectional structure of the fuel cell stack 100 at the position of III-III of FIG. It is explanatory drawing which shows the XZ cross section composition of two power generation units 102 adjacent to each other at the same position as the cross section shown in FIG. It is explanatory drawing which shows the YZ cross section configuration of two power generation units 102 adjacent to each other at the same position as the cross section shown in FIG. It is explanatory drawing which shows the XY cross-sectional structure of the power generation unit 102 at the position of VI-VI of FIG. It is explanatory drawing which shows the XY cross-sectional structure of the power generation unit 102 at the position of VII-VII of FIG. It is an XZ sectional view which shows the detailed structure of the cell side separator 120 and the IC side separator 180. It is explanatory drawing which shows the performance evaluation result. It is explanatory drawing which shows the performance evaluation result.

A. This embodiment:
A-1. Device configuration:
(Structure of fuel cell stack 100)
FIG. 1 is a perspective view showing an external configuration of the fuel cell stack 100 in the present embodiment, and FIG. 2 is a perspective view of the fuel cell stack 100 at the position II-II in FIG. 1 (and FIGS. 6 and 7 described later). It is explanatory drawing which shows the XZ cross-sectional structure, and FIG. 3 is the explanatory view which shows the YZ cross-sectional structure of the fuel cell stack 100 at the position III-III of FIG. 1 (and FIG. 6 and FIG. 7 which will be described later). Each figure shows XYZ axes that are orthogonal to each other to identify the direction. In the present specification, for convenience, the Z-axis positive direction is referred to as an upward direction, and the Z-axis negative direction is referred to as a downward direction, but the fuel cell stack 100 is actually in a direction different from such an orientation. It may be installed. The same applies to FIGS. 4 and later. 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 unit (hereinafter referred to as “power generation unit”) 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). The 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 on the peripheral edge of each layer (power generation unit 102, end plates 104, 106) constituting the fuel cell stack 100 around the Z axis. , The holes formed in each layer and corresponding to each other communicate with each other in the vertical direction to form a communication hole 108 extending in the vertical direction 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 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 bolt 22 and the nuts 24 fitted on both sides of the bolt 22. As shown in FIGS. 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 the bolt. An insulating sheet 26 is interposed between the nut 24 fitted on the other side (lower side) of the 22 and the lower surface of the end plate 106 constituting the lower end of the fuel cell stack 100. However, in the place where the gas passage member 27 described later is provided, the insulating sheets arranged on the upper side and the lower side of the gas passage member 27 and the gas passage member 27 between the nut 24 and the surface of the end plate 106, respectively. 26 is intervening. The insulating sheet 26 is made of, for example, a mica sheet, a ceramic fiber sheet, a ceramic dust sheet, a glass sheet, a glass-ceramic composite agent, 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 position is located near the midpoint of one side (the side on the positive side of the X axis among the two sides parallel to the Y axis) on the outer circumference of the fuel cell stack 100 around the Z axis. In the space formed by the bolt 22 (bolt 22A) and the communication hole 108 through which the bolt 22A is inserted, the oxidant gas OG is introduced from the outside of the fuel cell stack 100, and the oxidant gas OG is generated for each power generation. It functions as an oxidizer gas introduction manifold 161 that is a gas flow path supplied to the unit 102, and is the midpoint of the side opposite to the side (the side on the negative side of the X-axis of the two sides parallel to the Y-axis). The space formed by the bolt 22 (bolt 22B) located in the vicinity and the communication hole 108 through which the bolt 22B is inserted provides the oxidant off-gas OOG, which is the gas discharged from the air chamber 166 of each power generation unit 102. It functions as an oxidizer gas discharge manifold 162 that discharges to the outside of the fuel cell stack 100. In this embodiment, air is used as the oxidant gas OG. Further, in the present embodiment, a blower (not shown) is used for introducing the oxidant gas OG into the oxidant gas introduction manifold 161. Further, it is generated when heat exchange (for example, the oxidant off-gas OOG discharged from the fuel cell stack 100 and the fuel off-gas FOG are burned) before the oxidant gas OG is introduced into the oxidant gas introduction manifold 161. Preheating of the oxidant gas OG may be performed by utilizing heat exchange with heat).

As shown in FIGS. 1 and 3, the position is near the midpoint of one side (the side on the positive side of the Y axis among the two sides parallel to the X axis) on the outer circumference of the fuel cell stack 100 around the Z axis. In the space formed by the bolt 22 (bolt 22D) and the communication hole 108 through which the bolt 22D is inserted, the fuel gas FG is introduced from the outside of the fuel cell stack 100, and the fuel gas FG is used in each power generation unit 102. The bolt 22 (bolt) that functions as the fuel gas introduction manifold 171 to be supplied to the fuel gas introduction manifold and is located near the midpoint of the side opposite to the side (the side on the negative side of the Y axis among the two sides parallel to the X axis). The space formed by the 22E) and the communication hole 108 through which the bolt 22E is inserted discharges the fuel off-gas 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. Functions as a fuel gas discharge manifold 172. In this embodiment, as the fuel gas FG, for example, a hydrogen-rich gas obtained by reforming a city gas is used.

The fuel cell stack 100 is provided with four gas passage members 27. Each gas passage member 27 has a hollow cylindrical main body portion 28 and a hollow cylindrical branch portion 29 branched from the side surface of the main body portion 28. The hole of the branch portion 29 communicates with the hole of 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 main body 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. The hole of the main body 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 main body 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 fuel gas. The hole of the main body 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.

(Structure of end plates 104 and 106)
The pair of end plates 104 and 106 are substantially rectangular flat plate-shaped conductive members, and are made of, for example, stainless steel. One end plate 104 is located above the power generation unit 102 located at the top, and the other end plate 106 is located below the power generation unit 102 located at the bottom. A plurality of power generation units 102 are sandwiched by a pair of end plates 104 and 106 in a pressed state. The upper end plate 104 functions as a positive output terminal of the fuel cell stack 100, and the lower end plate 106 functions as a negative output terminal of the fuel cell stack 100.

(Structure of power generation unit 102)
FIG. 4 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, and FIG. 5 is an explanatory view showing the XZ cross-sectional configuration of the two power generation units 102 adjacent to each other at the same position as the cross section shown in FIG. It is explanatory drawing which shows the YZ cross-sectional structure of two power generation units 102. Further, FIG. 6 is an explanatory diagram showing an XY cross-sectional configuration of the power generation unit 102 at the position of VI-VI of FIG. 4, and FIG. 7 is an explanatory view of the XY cross-sectional configuration of the power generation unit 102 at the position of VII-VII of FIG. It is explanatory drawing which shows.

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, and a fuel. It includes a pole-side frame member 140, a fuel pole-side current collector 144, and a pair of interconnector members 150. A hole corresponding to the communication hole 108 through which the bolt 22 described above is inserted is formed in the peripheral portion around the Z axis of the cell side separator 120, the IC side separator 180, the air pole side frame member 130, and the fuel pole side frame member 140. Has been done. In addition, the single cell 110, the cell side separator 120, the IC side separator 180, the air pole side current collector 134, the fuel pole side frame member 140, the fuel pole side current collector 144, and the inter are in this embodiment. The composite including the connector member 150 corresponds to the IC-single cell composite in the claims, and the fuel pole side frame member 140 corresponds to the frame member in the claims.

The interconnector member 150 is a substantially rectangular flat plate-shaped conductive member, and is made of, for example, ferritic stainless steel. The interconnector member 150 ensures electrical conduction between the power generation units 102 and prevents mixing of the reaction gas between the power generation units 102. In this embodiment, when two power generation units 102 are arranged adjacent to each other, one interconnector member 150 is shared by two adjacent power generation units 102. That is, the upper interconnector member 150 in a certain 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. Further, since the fuel cell stack 100 includes a pair of end plates 104 and 106, the power generation unit 102 located at the top of the fuel cell stack 100 does not have the upper interconnector member 150 and is located at the bottom. The power generation unit 102 to be generated does not include the lower interconnector member 150 (see FIGS. 2 and 3). The interconnector member 150 constituting the power generation unit 102 faces the single cell 110 constituting the power generation unit 102 in the vertical direction.

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

The electrolyte layer 112 is a flat plate-shaped member having a substantially rectangular shape in the vertical direction, and is a dense layer. The electrolyte layer 112 is formed of, for example, a solid oxide such as YSZ (yttria-stabilized zirconia), ScSZ (scandia-stabilized zirconia), SDC (samarium-doped ceria), GDC (gadolinium-doped ceria), and perovskite-type oxide. There is. As described above, the single cell 110 of the present embodiment is a solid oxide fuel cell (SOFC) using a solid oxide as an electrolyte. The air electrode 114 is a substantially rectangular flat plate-shaped member smaller than the electrolyte layer 112 in the vertical direction, and is a porous layer. The air electrode 114 is formed of, for example, a perovskite-type oxide (for example, LSCF (lanternstrontium cobalt iron oxide), LSM (lanternstrontium manganese oxide), LNF (lantern nickel iron)). The fuel electrode 116 is a substantially rectangular flat plate-shaped member having substantially the same size as the electrolyte layer 112 in the vertical direction, and is a porous layer. The fuel electrode 116 is formed of, for example, a cermet composed of Ni and oxide ion conductive ceramic particles (for example, 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 formed of, for example, a metal material such as stainless steel. The cell-side separator 120 has a first through-hole peripheral portion 122 (see FIG. 8) which is a portion surrounding the first separator through-hole 121 in the cell-side separator 120. The downward surface of the surface of the first through hole peripheral portion 122 faces the peripheral edge portion of the surface of the electrolyte layer 112 constituting the single cell 110 on the side facing the air electrode 114 (upper side). .. The cell-side separator 120 is joined to the single cell 110 (electrolyte layer 112) by a first joining portion 124 containing a brazing material (for example, Ag wax) arranged in the first through hole peripheral portion 122. Therefore, the first through hole peripheral portion 122 is connected to the peripheral portion of the single cell 110. The cell-side separator 120 separates the air chamber 166 facing the air pole 114 and the fuel chamber 176 facing the fuel pole 116, and a gas leak from the air chamber 166 to the fuel chamber 176 at the peripheral edge of the single cell 110. It is suppressed.

A first glass seal portion 125 including glass is arranged on the air chamber 166 side 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 peripheral portion 122 of the cell-side separator 120 and the surface of the single cell 110 (in this embodiment, the electrolyte layer 112 constituting the single cell 110). It is formed to come into contact. The first glass seal portion 125 effectively suppresses a gas leak (cross leak) between the air chamber 166 and the fuel chamber 176.

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 partitions the fuel chamber 176 and the air chamber 166 facing the air electrode 114 of another adjacent single cell 110, from the air chamber 166 to the fuel chamber 176 at the peripheral edge of the interconnector member 150. Gas leaks are suppressed.

The IC-side separator 180 has a second through-hole peripheral portion 182 (see FIG. 8) which is a portion surrounding 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 edge of the interconnector member 150 on the lower surface of the second through-hole peripheral portion 182. Therefore, of the IC-side separator 180, the second through-hole peripheral portion 182 that surrounds the second separator through-hole 181 in the vertical direction is connected to the peripheral edge portion of the interconnector member 150. In the present embodiment, since the IC side separator 180 is joined by welding as described above, the 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 in which a substantially rectangular air chamber hole 131 penetrating in the vertical direction is formed near the center, and is, for example, mica or the like. It is formed of an insulator. Of the air electrode side frame member 130, the portion surrounding the air chamber hole 131 in the vertical direction is the outer peripheral portion of the surface of the side (upper side) facing the air chamber 166 in the surface of the cell side separator 120. , It is in contact with the outer peripheral portion of the surface of the side (lower side) facing the air chamber 166 in the surface of the IC side separator 180. The air chamber hole 131 formed in the air electrode side frame member 130 constitutes an air chamber 166 facing the air electrode 114. Further, 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 from each other. Further, in the air electrode side frame member 130, the oxidant gas supply communication flow path 132 that communicates the oxidant gas introduction manifold 161 and the air chamber 166, and the oxidation that communicates the air chamber 166 and the oxidant gas discharge manifold 162. The agent gas discharge communication flow path 133 is formed.

As shown in FIGS. 4, 5 and 7, the fuel pole side frame member 140 is a frame-shaped member having a substantially rectangular fuel chamber hole 141 formed in the vicinity of the center in the vertical direction, for example. It is made of metal. Of the fuel electrode side frame member 140, the portion surrounding the fuel chamber hole 141 in the vertical direction is the outer peripheral portion of the surface of the cell side separator 120 on the side facing the fuel chamber 176 (lower side). And the outer peripheral portion of the surface on the side (upper side) facing the fuel chamber 176 in the surface of the IC side separator 180. The fuel chamber hole 141 formed in the fuel pole side frame member 140 constitutes the fuel chamber 176 facing the fuel pole 116. Further, the fuel electrode side frame member 140 has a fuel gas supply communication flow path 142 that communicates the fuel gas introduction manifold 171 and the fuel chamber 176, and a fuel gas discharge communication 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 air electrode side current collector 134 is arranged in the air chamber 166. The air electrode side current collector 134 is composed of a plurality of substantially square columnar current collector elements 135, and is formed of, for example, ferritic stainless steel. The air pole side current collector 134 is in contact with the surface of the air pole 114 on the side opposite to the side facing the electrolyte layer 112 and the surface of the interconnector member 150 on the side facing the air pole 114. However, as described above, since the power generation unit 102 located at the top of the fuel cell stack 100 does not have the upper interconnector member 150, the air electrode side current collector 134 in the power generation unit 102 has an upper end. It is in contact with the plate 104. Since the current collector 134 on the air electrode side has such a configuration, the air electrode 114 and the interconnector member 150 (or the end plate 104) are electrically connected to each other. The air electrode side current collector 134 may be covered with a conductive coat, and a conductive bonding layer for bonding the air electrode 114 and the air electrode side current collector 134 may be provided between the air electrode 114 and the air electrode side current collector 134. It may be intervening. Further, 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 in 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 connecting the electrode facing portion 145 and the interconnector facing portion 146, for example, nickel or nickel alloy. , Stainless steel, etc. 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 the surface of the interconnector member 150 on the side facing the fuel pole 116. Is in contact with. However, as described above, since the power generation unit 102 located at the bottom of the fuel cell stack 100 does not have the lower interconnector member 150, the interconnector facing portion 146 in the power generation unit 102 has a lower end. It is in contact with the plate 106. Since the current collector 144 on the fuel electrode side has such a configuration, the fuel electrode 116 and the interconnector member 150 (or the end plate 106) are electrically connected to each other. A spacer 149 formed of, for example, a mica 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 the temperature cycle and the reaction gas pressure fluctuation, and the fuel electrode 116 and the interconnector member 150 (or the end plate 106) via the fuel electrode side current collector 144 follow. ) And the electrical connection is well maintained.

A-2. Operation of fuel cell stack 100:
As shown in FIGS. 2 and 4, the oxidant gas OG is supplied via 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 oxidant gas OG is supplied to the oxidant gas introduction manifold 161 through the holes of the branch portion 29 and the main body portion 28 of the gas passage member 27, and the oxidant gas introduction manifold 161 oxidizes each power generation unit 102. It is supplied to the air chamber 166 via the agent gas supply communication flow path 132. Further, as shown in FIGS. 3 and 5, the fuel gas FG is supplied via 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 through the holes of the branch portion 29 and the main body portion 28 of the gas passage member 27, and the fuel gas supply communication of each power generation unit 102 is performed 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, oxygen contained in the oxidant gas OG and hydrogen contained in the fuel gas FG in the single cell 110 are supplied. Power is generated by an electrochemical reaction with. This power generation reaction is an exothermic reaction. In each power generation unit 102, the air pole 114 of the single cell 110 is electrically connected to one of the interconnector members 150 via the air pole side current collector 134, and the fuel pole 116 is via the fuel pole side current collector 144. Is electrically connected to the other interconnector member 150. Further, the plurality of power generation units 102 included in the fuel cell stack 100 are electrically connected in series. Therefore, the electric energy generated in each power generation unit 102 is taken out from the end plates 104 and 106 that function as the output terminals of the fuel cell stack 100. Since the SOFC generates electricity at a relatively high temperature (for example, 700 ° C. to 1000 ° C.), the fuel cell stack 100 is a heater (for example, until the high temperature can be maintained by the heat generated by the power generation after the start-up. It may be heated by (not shown).

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 via the oxidant gas discharge communication flow path 133, and further. A fuel cell stack 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 oxidant gas discharge manifold 162. It is discharged to the outside of 100. Further, 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 via the fuel gas discharge communication flow path 143, and further fuels. 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. Is discharged to.

In the following, the combination of the air electrode side frame member 130 and the fuel electrode side frame member 140 is referred to as "frame member 200", and the combination of the air chamber hole 131 and the fuel chamber hole 141 is referred to as "frame penetration". The portion of the frame member 200 that surrounds the frame through hole 201 in the vertical direction is referred to as a “hole 201” (see FIG. 8). The frame member 200 corresponds to the frame member within the scope of the claims.

As described above, the portion of the air electrode side frame member 130 that surrounds the air chamber hole 131 in the vertical direction is the outer periphery of the surface of the surface of the cell side separator 120 on the side facing the air chamber 166. The portion is in contact with the outer peripheral portion of the surface of the surface of the IC side separator 180 on the side facing the air chamber 166. Further, in the fuel electrode side frame member 140, the portion 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 on the side facing the fuel chamber 176. It is in contact with the outer peripheral portion of the surface of the surface of the IC side separator 180 on the side facing the fuel chamber 176. As is clear from the above, of the frame member 200, the frame through hole peripheral portion 202 surrounding the frame through hole 201 in the vertical direction 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 a detailed configuration of the cell side separator 120 and the IC side separator 180. FIG. 8 shows the configuration of the Px portion of FIG. 4 in an enlarged manner. The cross section of the fuel cell stack 100 shown in FIGS. 4 and 8 is a cross section that passes through the center point PO (see FIG. 6 or FIG. 7) of the single cell 110 in the vertical direction and is parallel to the vertical direction. The cross section of the fuel cell stack 100 shown in FIG. 4 corresponds to the first specific cross section in the claims and corresponds to the second specific cross section.

In the fuel cell stack 100 of the present embodiment, the cell-side separator 120 and the IC-side separator 180 shown below are configured in an arbitrary cross section that passes through the center point PO of the single cell 110 in the vertical direction and is parallel to the vertical direction. Has been adopted. The cross sections shown in FIGS. 4 and 8 are examples of arbitrary cross sections that pass through the center point PO of the single cell 110 in the vertical direction and are parallel to the vertical direction.

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

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

The first straight line portion 126 is located between the single 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 straight line portion 126 corresponds to the second direction in the claims.

The second straight line portion 127 is located between the first straight line portion 126 in the X-axis direction and the frame member 200, 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 projects downward with respect to both the first straight portion 126 and the second straight portion 127. ing. The first connecting portion 128 has a curved shape so as to project 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. The length H1 at which the first connecting portion 128 protrudes from the first straight portion 126 or the second straight portion 127 (hereinafter referred to as “first connecting portion depth”) is 0. It is 2 mm or more, for example, 1 mm. The first connecting portion 128 is formed, for example, by press working.

As described above, the cell-side separator 120 includes a first connecting portion 128 projecting downward with respect to both the first straight portion 126 and the second straight portion 127 to generate electricity in the fuel cell stack 100. 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, so that the stress generated in the single cell 110 can be relieved, and by extension, the single cell 110 is simple. Deformation and cracking of the single cell 110 due to the 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 has a first bottom portion 128a located at the end of the first connecting portion 128 in the protruding direction (lower in the present embodiment), a first bottom portion 128a, and a first straight line portion 126. It has a first connecting portion 128b to be connected and a second connecting portion 128c connecting the first bottom portion 128a and the second straight line portion 127. The first bottom portion 128a is located below both the first straight line portion 126 and the second straight line portion 127.

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

The above-mentioned "length of the first bottom portion 128a in the X-axis direction (direction orthogonal to the vertical direction)" is the boundary portion B11 (first) of the first connecting portion 128 of the cell-side separator 120, which will be described later. A portion connecting the bottom portion 128a and the boundary portion B12 (the boundary portion B11 between the first bottom portion 128a and the first connection portion 128b) and the boundary portion B12 (the 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), the value of L2 is 6 (mm), and in this case, the value of L1 / L2 is 2.2.

Further, in the cell-side separator 120, the boundary portion B1 between the first straight line portion 126 and the first connecting portion 128 becomes lower as it is located in the negative direction of the X-axis in the Y-axis direction, and the radius of curvature becomes smaller. It is curved so as to be 0.8 mm or more. Here, in the cell-side separator 120, "the boundary portion γ between a certain portion α and a certain portion β is curved so that the radius of curvature is 0.8 mm or more" means that the surface of the cell-side separator 120 is curved. Of (at least one of the surface facing the air chamber 166 or the surface facing the fuel chamber 176), the boundary point γ0 between the partial α and the partial β and 0.29 mm away from the boundary point γ0 on the side of the single cell 110. The portion between the point γ1 and the point γ1 is a curve having a radius of curvature of 0.8 mm or more, and the boundary point γ0 and the point γ2 separated from the boundary point γ0 by 0.29 mm on the opposite side of the point γ1. The part between them means that the curve has a radius of curvature of 0.8 mm or more (the same applies hereinafter). Note that Bp10 in FIG. 8 indicates a boundary point between the first straight line portion 126 and the first connecting portion 128 on the surface of the cell-side separator 120, and Bp11 is located on the side of the single cell 110 from the boundary point Bp10. A point separated by 0.29 mm is shown, and Bp12 indicates a point separated from the boundary point Bp10 on the opposite side of the point Bp11 by 0.29 mm.

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

Further, of 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 located in the positive direction of the X axis in the Y-axis direction. Moreover, it is curved so that the radius of curvature is 0.8 mm or more.

Further, of 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 located in the negative direction of the X axis in the Y-axis direction. Moreover, it is curved so that the radius of curvature is 0.8 mm or more.

The first straight line portion 126, the second straight line portion 127, and the first connecting portion 128 are formed so as to surround the first separator through hole 121 in the vertical direction (FIG. 6). reference). The second straight line portion 127 is located on the outer peripheral side of the cell side separator 120 with respect to the first straight line portion 126 in the vertical view.

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

The second connecting portion 188 connects the third straight portion 186 and the fourth straight portion 187, and projects downward with respect to both the third straight portion 186 and the fourth straight portion 187. ing. The second connecting portion 188 has a curved shape so as to project 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 line portion 186 has a second bottom portion 188a located at the end of the second connecting portion 188 in the protruding direction (lower in the present embodiment), a second bottom portion 188a, and a third straight line portion 186. It has a third connecting portion 188b to be connected and a fourth connecting portion 188c connecting the second bottom portion 188a and the fourth straight line portion 187. The second bottom portion 188a is located below both the third straight line portion 186 and the fourth straight line portion 187.

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

The meaning of the above-mentioned "length of the second bottom portion 188a in the X-axis direction" is defined by the same concept as the meaning of 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, the boundary portion B13 (boundary portion B13 between the second bottom portion 188a and the third connecting portion 188b) and the boundary portion B14 (second bottom portion) described later. It means the length in the X-axis direction of the portion connecting the boundary portion B14) between the 188a and the fourth connecting portion 188c.

Of the IC-side separator 180, the boundary portion B3 between the third straight line portion 186 and the second connecting portion 188 becomes lower as it is located in the negative direction of the X-axis in the Y-axis direction, and the radius of curvature is 0. It is curved so that it is 8 mm or more.

Of the IC-side separator 180, the boundary portion B4 between the second connecting portion 188 and the fourth straight line portion 187 is lowered so as to be positioned in the positive direction of the X-axis in the Y-axis direction, and the radius of curvature is 0. It is curved so that it is 8 mm or more.

Further, of 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 located in the positive direction of the X axis in the Y-axis direction. Moreover, it is curved so that the radius of curvature is 0.8 mm or more.

Further, of 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 located in the negative direction of the X axis in the Y-axis direction. Moreover, it 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 the present 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 (air pole-side frame member 130 and fuel pole-side frame member 140). The single cell 110 includes an electrolyte layer 112, and an air pole 114 and a fuel pole 116 that face each other in the vertical direction with the electrolyte layer 112 interposed therebetween. The cell-side separator 120 is formed with a first separator through hole 121 that penetrates in the vertical direction. Of the cell-side separator 120, the first through-hole peripheral portion 122 that surrounds the first separator through-hole 121 in the vertical direction is connected to the peripheral edge portion of the single cell 110. The cell-side separator 120 partitions an air chamber 166 facing the air pole 114 and a fuel chamber 176 facing the fuel pole 116. The frame member 200 is formed with a frame through hole 201 that penetrates in the vertical direction and constitutes a fuel chamber 176 and an air chamber 166. Among the frame members 200, the frame through hole peripheral portion 202 surrounding the frame through hole 201 in the vertical direction is connected to the outer peripheral portion of the cell side separator 120. In the cross section parallel to the vertical direction in the fuel cell stack 100 (for example, the cross section shown in FIGS. 4 and 8, hereinafter referred to as “the first specific cross section”), the cell side separator 120 is the first straight portion 126. , A second straight portion 127 and a first connecting portion 128 are provided. The first straight line portion 126 is located 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 a "first orthogonal direction"). , Extends in the first orthogonal direction. The second straight line portion 127 is located between the first straight line 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 projects downward with respect to 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 single cell 110 and the frame member 200 in the first orthogonal direction, and L2 is the length of the second bottom 188a of the first connecting portion 128 in the first orthogonal direction. be.

In the fuel cell stack 100 of the present embodiment, the fuel cell stack 100 satisfies the formula: L1 / L2 ≦ 4.3, so that the fuel cell stack 100 does not satisfy the formula: L1 / L2 ≦ 4.3. The accumulation of strain in the first connecting portion 128 when exposed to a thermal cycle is suppressed. Therefore, according to the fuel cell stack 100 of the present embodiment, it is possible to prevent fatigue fracture from occurring in the cell-side separator 120 due to the accumulation of strain in the first connecting portion 128.

The larger the thickness T1 of the cell-side separator 120 (first straight line portion 126, second straight line portion 127, first connecting portion 128), the larger the strain accumulated in the first connecting portion 128 tends to be. There is. Therefore, from the viewpoint of suppressing fatigue fracture in 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. It is preferably 3 mm or less, and more preferably 0.1 mm or less.

Further, in a configuration in which the value of L1 / L2 is larger than 4.3, when the fuel cell stack 100 is exposed to a thermal cycle, the cell-side separator 120 undergoes inelastic deformation (plastic deformation or creep deformation). As a result, the gas flow path in the air chamber 166 or the fuel chamber 176 is blocked or reduced, so that the gas flow distribution is hindered 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 may be blocked or reduced, which may cause a problem that the power generation performance of the fuel cell stack 100 is deteriorated. On the other hand, in the fuel cell stack 100 of the present embodiment, by satisfying the formula: L1 / L2 ≦ 4.3 as described above, the cell-side separator 120 is suppressed from being inelastically deformed, and eventually the fuel. 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, the power generation performance can be improved. The reason why the effect is obtained by the above configuration is not necessarily clear, but by satisfying L1 / L2 ≦ 4.3, the first connection when the fuel cell stack 100 is exposed to the thermal cycle as described above. It is presumed that this is due to the suppression of strain accumulation in the portion 128.

Further, in the fuel cell stack 100 of the present embodiment, in the first specific cross section, the boundary portion B1 between the first straight line portion 126 and the first connecting portion 128 and the first connecting portion of the cell side separator 120 are connected. The boundary portion B2 between the portion 128 and the second straight portion 127 is curved so that the radius of curvature is 0.8 mm or more.

According to the fuel cell stack 100 of the present embodiment, the boundary portions B1 and B2 are curved so that the radius of curvature is 0.8 mm or more, so that the boundary portions B1 and B2 are bent. Compared with the above configuration, the accumulation of strain in the boundary portions B1 and B2 is suppressed, and as a result, the strain is accumulated in the first connecting portion 128, so that fatigue fracture occurs in the cell side separator 120. This can be suppressed more effectively.

Further, in the fuel cell stack 100 of the present embodiment, the power generation unit 102 includes an interconnector member 150 that faces the single cell 110 in the vertical direction, and an IC-side separator 180. The IC-side separator 180 is formed with a second separator through hole 181 that penetrates in the vertical direction. Of the IC-side separator 180, the second through-hole peripheral portion 182 that surrounds the second separator through-hole 181 in the vertical direction is connected to the peripheral edge portion of the interconnector member 150. The IC-side separator 180 partitions an air chamber 166 facing the air pole 114 and a fuel chamber 176 facing the fuel pole 116. In the cross section parallel to the vertical direction in the fuel cell stack 100 (for example, the cross section shown in FIGS. 4 and 8; hereinafter referred to as “the second specific cross section”), the IC side separator 180 has a third straight portion 186. , A fourth straight portion 187 and a second connecting portion 188. The third straight line portion 186 is located between the single cell 110 and the frame member 200 in a cross section parallel to the vertical direction in the second specific cross section (hereinafter referred to as “second orthogonal direction”), and is a second. Extends in the orthogonal direction of. The fourth straight line portion 187 is located between the third straight line portion 186 in the second orthogonal direction and the frame member 200, and extends in the second orthogonal direction. The second connecting portion 188 connects the third straight line portion 186 and the fourth straight line portion 187, and vertically with respect to both the third straight line portion 186 and the fourth straight line portion 187. It stands out. 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 single 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 fuel cell stack 100 satisfies the formula: L3 / L4 ≦ 4.3, so that the fuel cell stack 100 does not satisfy the formula: L3 / L4 ≦ 4.3. The accumulation of strain in the second connecting portion 188 when exposed to a thermal cycle is suppressed. Therefore, according to the fuel cell stack 100 of the present embodiment, it is possible to prevent fatigue fracture from occurring in the IC-side separator 180 due to the accumulation of strain in the second connecting portion 188.

Similar to the thickness T1 of the cell-side separator 120 described above, the larger the thickness T2 of the IC-side separator 180 (third straight line portion 186, fourth straight line portion 187, second connecting portion 188), the larger the thickness T2. The strain accumulated in the second connecting portion 188 tends to be large. Therefore, from the viewpoint of suppressing fatigue fracture in 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. It is preferably 3 mm or less, and more preferably 0.1 mm or less.

Similar to the inelastic deformation of the cell-side separator 120 as described above, in a configuration where the value of L3 / L4 is larger than 4.3, when the fuel cell stack 100 is exposed to the thermal cycle, the IC side The separator 180 is inelastically deformed, which blocks the gas flow path in the air chamber 166 or the fuel chamber 176 and hinders the flow of gas, which causes problems such as deterioration of 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, by satisfying the formula: L3 / L4 ≦ 4.3 as described above, the IC-side separator 180 is suppressed from being inelastically deformed, and eventually the fuel. It is possible to more effectively suppress 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, the 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 straight line portion 186 and the second connecting portion 188 and the second connecting portion of the cell side separator 120 are connected. The boundary portion B4 between the portion 188 and the fourth straight line portion 187 is curved so that the radius of curvature is 0.8 mm or more.

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

A-5. Performance evaluation:
Next, the performance evaluation of this embodiment will be described. Performance evaluation (performance evaluation regarding durability against fatigue fracture of the separator) was performed on samples of a plurality of fuel cell stacks 100 having different characteristics from each other by simulation. 9 and 10 are explanatory views showing the performance evaluation results. In this performance evaluation, a fuel cell stack 100 including a plurality of single cells 110 (power generation unit 102) was configured, and the strain accumulated in the cell side separator 120 and the IC side separator 180 when power generation operation was performed was measured.

FIG. 9 shows the results of evaluation of the durability of the cell-side separator 120 and the IC-side separator 180 against fatigue fracture. As shown in FIG. 9, six samples (samples S1 to S6) of the fuel cell stack 100 were used for this performance evaluation. In each sample, the values of L1 are the same as each other, the values of L2 are different from each other, and therefore the values of L1 / L2 are different from each other. FIG. 10 shows the result 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 the power generation operation is performed under the above-mentioned operating conditions.

“Large” in the “Strain increase amount (Δε)” column of FIG. 9 indicates that the amount of strain accumulated in the cell side separator 120 and the IC side separator 180 is large, and is “small”. "" Indicates that the amount of the strain 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 judged that there is a high risk of fatigue fracture in the cell side separator 120 and the IC side separator 180, and the evaluation was “x (failure)”. Further, 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 is not excessive. , The cell side separator 120 and the IC side separator 180 were judged to have a low risk of fatigue failure, and were evaluated as “◯ (pass)”.

As shown in FIG. 9, in the samples S1 and S2, the amount of strain accumulated in the cell-side separator 120 and the IC-side separator 180 was “large”, so that the sample S1 and S2 were evaluated as “x”. On the other hand, in the samples S3 to S6, the amount of strain accumulated in the cell-side separator 120 and the IC-side separator 180 was “small”, so that the sample was evaluated as “◯”. Here, in the samples S1 and S2, the value of L1 / L2 is larger than 4.3, while in the 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 as compared with the configuration in which the value of L1 / L2 is larger than 4.3. It was confirmed that it is possible to suppress 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 larger the value of L2, the smaller the amount of strain accumulated in the cell-side separator 120 and the IC-side separator 180.

B. Modification example:
The technique disclosed in the present specification is not limited to the above-described embodiment, and can be transformed into various forms without departing from the gist thereof, and for example, the following modifications are also 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 single cell 110 in the vertical direction and are parallel to the vertical direction. Although the configuration is adopted, the configuration of the cell-side separator 120 and the IC-side separator 180 described above can be obtained only in any of the cross sections that pass through the center point PO of the single cell 110 in the vertical direction and are parallel to the vertical direction. It may be adopted. Further, in the fuel cell stack 100 of the above embodiment, the above-mentioned configuration of the cell-side separator 120 and the above-mentioned configuration of the IC-side separator 180 may be adopted in different cross sections.

Further, in the above embodiment (or a modified example, the same applies hereinafter), the first connecting portion 128 has a configuration that protrudes upward with respect to both the first straight line portion 126 and the second straight line portion 127. You may. Also in this configuration, the 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 first connecting portion 128 projects downward. Further, the second connecting portion 188 connects the third straight line portion 186 and the fourth straight line portion 187, and is downward with respect to both the third straight line portion 186 and the fourth straight line portion 187. It may be a configuration that protrudes from the surface. Also in this configuration, the 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 projects downward.

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

Further, in the frame member 200, the frame through hole 201 may form 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 only an example, and the number of power generation units 102 is appropriately determined according to the output voltage and the like required for the fuel cell stack 100. Further, in the above embodiment, an intermediate layer may be arranged between the air electrode 114 and the electrolyte layer 112. Further, the material constituting each member in the above embodiment is merely an example, and each member may be composed of another material.

In the above embodiment, the SOFC that generates power by utilizing the electrochemical reaction between hydrogen contained in the fuel gas and oxygen contained in the oxidizing agent gas is targeted, but the present invention utilizes the electrolysis reaction of water. It is also applicable to an electrolytic cell unit, which is a constituent unit of a solid oxide type electrolytic cell (SOEC) that produces hydrogen, and an electrolytic cell stack having a plurality of electrolytic cell units. The configuration of the electrolytic cell stack is not described in detail here because it is known, for example, as described in Japanese Patent Application Laid-Open No. 2016-81813, but is schematically the same as the fuel cell stack 100 in the above-described embodiment. It is a composition. That is, the fuel cell stack 100 in the above-described embodiment may be read as an electrolytic cell stack, the power generation unit 102 may be read as an electrolytic cell unit, and the single cell 110 may be read as an electrolytic cell. However, during the operation of the electrolytic cell stack, a voltage is applied between both electrodes so that the air electrode 114 is positive (anode) and the fuel electrode 116 is negative (cathode), and the voltage is applied through the communication hole 108. Steam as a raw material gas is supplied. As a result, an electrolysis reaction of water occurs in each electrolytic cell unit, hydrogen gas is generated in the fuel chamber 176, and hydrogen is taken out to the outside of the electrolytic cell stack through the communication hole 108. Even in the electrolytic cell unit and the electrolytic cell stack having such a configuration, if the same configuration as that of the above 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: Insulation sheet 27: Gas passage member 28: Main body 29: Branch 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 peripheral part 124: First joint part 125 : First glass seal part 126: First straight part 127: Second straight part 128: First connecting part 128a: First bottom 128b: First connecting part 128c: Second connecting part 130: Air pole side frame member 131: Air chamber hole 132: Oxidating agent gas supply communication flow path 133: Oxidizing agent gas discharge communication flow path 134: Air pole side current collector 135: Current collector element 140: Fuel pole side frame member 141: Fuel chamber hole 142: Fuel gas supply communication flow path 143: Fuel gas discharge communication flow path 144: Fuel electrode side current collector 145: Electrode facing part 146: Interconnector facing part 147: Connecting part 149: Spacer 150: Interconnector member 161: Oxidizing agent gas introduction manifold 162: Oxidizing agent 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 peripheral part 186: Third straight part 187: Fourth straight part 188: Second connecting part 188a: Second bottom 188b: Third connecting part 188c: Fourth connecting part 200: Frame member 201: Frame through hole 202: Frame through hole peripheral part FG: Fuel gas FOG: Fuel off gas OG: Oxidating agent gas OOG: Oxidating agent off gas

Claims (8)

A single cell containing an electrolyte layer and an air electrode and a fuel electrode facing each other in a first direction across the electrolyte layer.
A first separator through hole penetrating in the first direction is formed, and a portion surrounding the first separator through hole in the first direction view is connected to the peripheral edge portion of the single cell. A cell-side separator that separates the air chamber facing the air electrode and the fuel chamber facing the fuel electrode.
A frame through hole that penetrates in the first direction and constitutes at least one of the fuel chamber and the air chamber is formed, and a portion surrounding the frame through hole in the first direction is the cell side. The 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 the first specific cross section, which is at least one cross section parallel to the first direction.
The cell-side separator is
A first straight line portion located between the single cell and the frame member in the second direction orthogonal to the first direction and extending in the second direction.
A second straight line portion located between the first straight line portion in the second direction and the frame member and extending in the second direction, and a second straight line portion.
The first straight line portion and the second straight line portion are connected to each other, and the first straight line portion and the second straight line portion project in the first direction with respect to both the first straight line portion and the second straight line portion. With the first connecting part having a bottom,
Equipped with
Satisfy the following equation (1),
It is characterized by an electrochemical reaction cell stack.
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,
Of the cell-side separators, the boundary portion between the first straight line portion and the first connecting portion and the boundary portion between the first connecting portion and the second straight line portion have a radius of curvature of 0. It is curved so that it is 8 mm or more,
It is characterized by an electrochemical reaction cell stack. In the electrochemical reaction cell stack according to claim 1 or 2.
The electrochemical reaction unit is
The single cell and the interconnector member facing the first direction,
A second separator through hole penetrating in the first direction is formed, and a portion surrounding the second separator through hole in the first direction is connected to a peripheral edge portion of the interconnector member. , An IC-side separator that separates the air chamber facing the air electrode and the fuel chamber facing the fuel electrode.
Equipped with
In the second specific cross section, which is at least one cross section parallel to the first direction.
The IC side separator is
A third straight line portion located between the single cell and the frame member in the second direction and extending in the second direction.
A fourth straight line portion located between the third straight line portion in the second direction and the frame member and extending in the second direction, and a fourth straight line portion.
The third straight line portion and the fourth straight line portion are connected to each other, projecting in the first direction with respect to both the third straight line portion and the fourth straight line portion, and the second straight portion. With a second connecting part with a bottom,
Equipped with
Satisfy the following equation (2),
It is characterized by an electrochemical reaction cell stack.
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,
Of the IC-side separators, the boundary portion between the third straight line portion and the second connecting portion and the boundary portion between the second connecting portion and the fourth straight line portion have a radius of curvature of 0. It is curved so that it is 8 mm or more,
It is characterized by an electrochemical reaction cell stack. A single cell containing an electrolyte layer and an air electrode and a fuel electrode facing each other in a first direction across the electrolyte layer.
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 in the first direction is connected to a peripheral portion of the single cell. With the side separator,
A frame member through which a frame through hole penetrating in the first direction is formed, and a portion surrounding the frame through hole in the first direction is connected to an outer peripheral portion of the cell side separator.
In an IC-single cell complex comprising
In the first specific cross section, which is at least one cross section parallel to the first direction.
The cell-side separator is
A first straight line portion located between the single cell and the frame member in the second direction orthogonal to the first direction and extending in the second direction.
A second straight line portion located between the first straight line portion in the second direction and the frame member and extending in the second direction, and a second straight line portion.
The first straight line portion and the second straight line portion are connected to each other, and the first straight line portion and the second straight line portion project in the first direction with respect to both the first straight line portion and the second straight line portion. With the first connecting part having a bottom,
Equipped with
Satisfy the following equation (1),
An IC-single cell complex characterized by this.
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 complex according to claim 5.
In the first specific cross section,
Of the cell-side separators, the boundary portion between the first straight line portion and the first connecting portion and the boundary portion between the first connecting portion and the second straight line portion have a radius of curvature of 0. It is curved so that it is 8 mm or more,
An IC-single cell complex characterized by this. In the IC-single cell complex according to claim 5 or 6.
Moreover,
The single cell and the interconnector member facing the first direction,
A second separator through hole penetrating in the first direction is formed, and a portion surrounding the second separator through hole in the first direction is connected to a peripheral edge portion of the interconnector member. IC side separator and
Equipped with
In the second specific cross section, which is at least one cross section parallel to the first direction.
The IC side separator is
A third straight line portion located between the single cell and the frame member in the second direction and extending in the second direction.
A fourth straight line portion located between the third straight line portion in the second direction and the frame member and extending in the second direction, and a fourth straight line portion.
The third straight line portion and the fourth straight line portion are connected to each other, projecting in the first direction with respect to both the third straight line portion and the fourth straight line portion, and the second straight portion. With a second connecting part with a bottom,
Equipped with
Satisfy the following equation (2),
An IC-single cell complex characterized by this.
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 complex according to claim 7.
In the second specific cross section,
Of the IC-side separators, the boundary portion between the third straight line portion and the second connecting portion and the boundary portion between the second connecting portion and the fourth straight line portion have a radius of curvature of 0. It is curved so that it is 8 mm or more,
An IC-single cell complex characterized by this.

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