JP2021022560A - Electrochemical reaction cell stack - Google Patents

Abstract

To suppress deterioration of the performance of an electrochemical reaction cell stack caused by the displacement difference between a frame member and a single cell in a first direction.SOLUTION: An electrochemical reaction cell stack includes an electrochemical reaction block in which a plurality of electrochemical reaction units each including a single cell and a frame member having a frame through-hole formed therein are arranged side by side in a first direction, and a pair of end members. In the end member is formed a space that opens at least on the electrochemical reaction block side, and has a contour line which involves the single cell when viewed in the first direction. The electrochemical reaction cell stack further includes a cell-side joint portion that is directly or indirectly joined to the single cell, and a frame-side joint portion joined to the frame member, and further includes a flexible member which is deformed so that the relative position between the cell-side joint portion and the frame-side joint portion in the first direction is displaced.SELECTED DRAWING: Figure 7

Description

The techniques disclosed herein relate to electrochemical reaction cell stacks.

A solid oxide fuel cell (hereinafter referred to as "SOFC") having an electrolyte layer containing a solid oxide is known as one of the types of fuel cells that generate electricity by utilizing an electrochemical reaction between hydrogen and oxygen. Has been done. A fuel cell single cell (hereinafter, simply referred to as “single cell”), which is a constituent unit of SOFC, has an electrolyte layer and air that faces each other in a predetermined direction (hereinafter, referred to as “first direction”) across the electrolyte layer. Includes poles and fuel poles.

SOFCs are generally used in the form of fuel cell stacks comprising electrochemical reaction blocks in which a plurality of electrochemical reaction units are arranged side by side in a first direction. The electrochemical reaction unit includes, for example, a single cell, a frame member, and a separator. The frame member is formed with a through hole constituting an air chamber facing the air electrode or a fuel chamber facing the fuel electrode. In the separator, a through hole is formed, a through hole peripheral portion surrounding the through hole is joined to a single cell, and a peripheral edge portion is joined to a frame member to partition an air chamber and a fuel chamber. The fuel cell stack further comprises a pair of end members located on either side of the electrochemical reaction block in the first direction and arranged so that at least a portion overlaps the frame member in the first direction (eg,). , Patent Document 1).

JP-A-2017-10709

By the way, in the above-mentioned fuel cell stack, it is conceivable that a space is formed in at least one of the pair of end members. The space formed in the end member is open at least toward the electrochemical reaction block side, and the contour line of the space includes a single cell in the first directional view. In the electrochemical reaction cell stack in which a space is formed in the end member in this way, for example, compared to a configuration in which no space is formed in the end member and the entire surface of the end member on the electrochemical reaction block side is flat. Since the loads received from the pair of end members of the frame member and the single cell in the electrochemical reaction block are different from each other, a displacement difference between the frame member and the single cell is likely to occur in the first direction. Then, for example, due to a heat cycle, heat shock, or the like, the displacement difference between the frame member and the single cell in the first direction becomes even larger. When a displacement difference between the frame member and the single cell occurs in the first direction, for example, a force for pulling the single cell in the first direction is generated via a separator, so that the single cell is cracked or the frame member is cracked. There is a problem that the performance of the electrochemical reaction cell stack is deteriorated, such as the sealing property is deteriorated.

In addition, such a problem is an electrolytic cell including a plurality of electrolytic single cells 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. It is also a common issue for 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 fuel cell stack and the electrolytic cell stack are collectively referred to as an electrochemical reaction cell stack. Further, such a problem is common not only to SOFC and SOEC but also to other types of electrochemical reaction cell stacks.

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

The technique disclosed in the present specification can be realized, for example, in the following forms.

(1) The electrochemical reaction cell stack 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, and the air electrode. An electrochemical reaction block in which a plurality of electrochemical reaction units including an air electrode side frame member having an air electrode side frame through hole forming a facing air chamber and a plurality of electrochemical reaction units are arranged side by side in the first direction, and the above. Electricity comprising a pair of end members located on both sides of the first direction of the electrochemical reaction block and arranged so that at least a part thereof overlaps the air electrode side frame member in the first direction view. In the chemical reaction cell stack, at least one of the pair of end members has at least a space that opens toward the electrochemical reaction block side, and a space whose contour line includes the single cell in the first direction view. It is further provided with a cell-side joint that is formed and is directly or indirectly joined to the single cell, and an air-pole-side frame-side joint that is joined to the air-pole-side frame member. A first flexible member having flexibility that deforms so that the relative positions of the cell-side joint and the air-pole-side frame-side joint in the first direction are displaced is provided.

In this electrochemical reaction cell stack, a space is formed in at least one of the pair of end members. This space is open at least on the side of the electrochemical reaction block, and the contour line includes a single cell in the first directional view, which is the direction in which the plurality of electrochemical reaction units are arranged. In the electrochemical reaction cell stack in which a space is formed in the end member in this way, for example, compared to a configuration in which no space is formed in the end member and the entire surface of the end member on the electrochemical reaction block side is flat. , The displacement difference between the air electrode side frame member and the single cell in the electrochemical reaction block in the first direction due to the different loads received from the pair of end members between the air electrode side frame member and the single cell. Is likely to occur. Then, for example, due to a heat cycle, heat shock, or the like, the displacement difference between the air electrode side frame member and the single cell in the first direction becomes even larger. When a displacement difference occurs between the air electrode side frame member and the single cell in the first direction, for example, the electrochemical reaction block is formed via the first flexible member joined to the single cell and the air electrode side frame member. The performance of the electrochemical reaction cell stack is improved, such as cracks in the electrochemical reaction block (single cell, etc.) due to being pulled in the first direction, and deterioration of the sealing performance by the frame member on the air electrode side. It may decrease. On the other hand, according to the present electrochemical reaction cell stack, the first flexible member is in the first direction of the cell side joint portion and the air electrode side frame side joint portion in the first flexible member. Since it has the flexibility to deform so that its relative position is displaced, when the displacement difference between the air electrode side frame member and the single cell in the first direction becomes large, the first flexible member is deformed and the first flexible member is deformed. As a result, the stress generated in the single cell or the air electrode side frame member is relaxed by the above displacement difference, so that the electrochemical reaction cell stack caused by the displacement difference between the air electrode side frame member and the single cell in the first direction It is possible to suppress the deterioration of performance.

(2) In the electrochemical reaction cell stack, the first flexible member includes an inner portion including the cell-side joint portion, an outer portion located on the outer peripheral side of the inner portion, the inner portion, and the said. A configuration may be configured in which the outer portion is connected and the connecting portion is provided so as to project to one side in the first direction with respect to both the inner portion and the outer portion.

According to this electrochemical reaction cell stack, the connecting portion of the first flexible member functions like a spring that easily expands and contracts, and the first flexible member is easily deformed at the position of the connecting portion. When the displacement difference between the air electrode side frame member and the single cell in the first direction becomes large, the first flexible member is deformed so as to extend mainly at the position of the connecting portion, and as a result, the displacement difference simply causes the first flexible member to extend at the position of the connecting portion. Since the stress generated in the cell and the air electrode side frame member is relaxed, the deterioration of the performance of the electrochemical reaction cell stack due to the displacement difference between the air electrode side frame member and the single cell in the first direction can be suppressed. Can be done.

(3) In the electrochemical reaction cell stack, in at least one cross section parallel to the first direction, the cell-side joint portion and the air electrode-side frame-side joint portion of the first flexible member The first distance, which is the distance in the third direction orthogonal to the first direction, is the distance between the cell-side joint portion and the air electrode-side frame-side joint portion of the first flexible member. The configuration may be longer than the second distance, which is the distance in the first direction.

In the present electrochemical reaction cell stack, in at least one cross section parallel to the first direction, the cell side joint portion and the air electrode side frame side joint portion of the first flexible member are orthogonal to the first direction. The first distance, which is the distance in the third direction, is the second distance, which is the distance in the first direction between the cell-side joint portion and the air electrode-side frame-side joint portion of the first flexible member. Longer. Therefore, for example, a surface orthogonal to the first direction of the first flexible member under the condition that the second distance is the same as compared with the configuration in which the first distance is equal to or less than the second distance. The inclination with respect to the direction is gentle, and as a result, the stress generated in the single cell and the air electrode side frame member in the first direction is small. Therefore, according to the present electrochemical reaction cell stack, the deterioration of the performance of the electrochemical reaction cell stack due to the displacement difference between the air electrode side frame member and the single cell in the first direction can be more effectively suppressed. Can be done.

(4) In the electrochemical reaction cell stack, in at least one cross section parallel to the first direction, the length of the connecting portion in the first flexible member is the length of the first flexible member. Among them, a third direction orthogonal to the first direction between the cell-side joint and the air-pole-side frame-side joint from the shortest distance between the cell-side joint and the air-pole-side frame-side joint. The configuration may be longer than the length obtained by subtracting the first distance, which is the distance of.

According to the Electrochemical Reaction Cell Stack, in at least one cross section parallel to the first direction, for example, the length of the connecting portion in the first flexible member is the cell in the first flexible member. A first distance from the shortest distance between the side joint and the air pole side frame side joint in a third direction orthogonal to the first direction between the cell side joint and the air pole side frame side joint. Compared to the configuration in which the length is less than or equal to the length obtained by subtracting the distance, the stress generated in the single cell or the air electrode side frame member due to the displacement difference between the air electrode side frame member and the single cell in the first direction is increased. It can be effectively relaxed by the extension of the connecting portion of the first flexible member.

(5) In the electrochemical reaction cell stack, in the electrochemical reaction block, a first separator through hole is further formed in each electrochemical reaction unit, and a first separator through hole surrounds the first separator through hole. A plurality of first peripheral portions are joined to the single cell and a first peripheral edge portion is joined to the air electrode side frame member to partition the air chamber and the fuel chamber facing the fuel electrode. The configuration may include one separator, and at least one of the first separators may be the first flexible member.

According to the present electrochemical reaction cell stack, by applying the configuration of the first flexible member to at least one first separator, the displacement difference between the air electrode side frame member and the single cell in the first direction. It is possible to suppress the deterioration of the performance of the electrochemical reaction cell stack due to the above.

(6) In the electrochemical reaction cell stack, the electrochemical reaction block further constitutes a plurality of interconnectors arranged in the first direction of each single cell and a fuel chamber facing the fuel electrode. A fuel pole side frame member having a fuel pole side frame through hole formed therein and a second through hole through hole are formed, and a portion around the second through hole surrounding the second separator through hole is joined to the interconnector. At the same time, a second peripheral edge portion is joined to the fuel pole side frame member, and the fuel chamber is provided with a plurality of second separators for partitioning the fuel chamber and the air chamber of the other adjacent single cell. One said second separator comprises a connector side joint that is directly or indirectly joined to the interconnector and a fuel pole side frame side joint that is joined to the fuel pole side frame member. Further, the configuration is also a configuration in which the second flexible member has flexibility that deforms so that the relative position of the connector side joint portion and the fuel pole side frame side joint portion in the first direction is displaced. Good.

According to the present electrochemical reaction cell stack, by applying the configuration of the second flexible member to at least one second separator, the displacement difference between the fuel electrode side frame member and the single cell in the first direction. It is possible to suppress the deterioration of the performance of the electrochemical reaction cell stack due to the above.

(7) In the electrochemical reaction cell stack, the thickness of the second separator in the first direction is thinner than the thickness of the interconnector in the first direction, and is more flexible than the interconnector. It may be configured as a member having a high value.

According to the present electrochemical reaction cell stack, at least one second separator is more easily bent and deformed than an interconnector bonded to the second separator. Therefore, when the displacement difference between the air electrode side frame member and the single cell in the first direction becomes large, the second separator is deformed so as to bend. As a result, the stress generated in the single cell or the air-side frame member is relaxed by the displacement difference, so that the electrochemical reaction cell stack caused by the displacement difference between the air electrode-side frame member and the single cell in the first direction It is possible to suppress the deterioration of performance.

(8) In the electrochemical reaction cell stack, at least one of the second separators may be joined to the interconnector and the fuel electrode side frame member by welding. Therefore, the presence of the second separator suppresses the leakage of gas from the fuel chamber to the air chamber, and can improve the airtightness of each gas chamber between the air chamber and the fuel chamber.

(9) In the electrochemical reaction cell stack, the space is formed in the first end member which is one of the pair of end members, and the electrochemical reaction cell stack further comprises the first end member. A terminal member located between the electrochemical reaction block and the first end member in one direction and arranged so that at least a part thereof overlaps with the air electrode side frame member. A conductive terminal member having a terminal member through hole formed in the first end member and communicating with the space, and the first end in the first direction. An insulating member located between the member and the terminal member, at least a part of which is arranged so as to overlap the air electrode side frame member, penetrates in the first direction, and has the first end. Of the insulating insulating member having an insulating member through hole formed in the member and having an insulating member through hole communicating with the space, and a plurality of interconnectors arranged in the first direction of each single cell, the first one. In the direction of, a specific interconnector having the shortest distance from the terminal member and a third separator through hole are formed, and a portion around the third through hole surrounding the third separator through hole becomes the specific interconnector. A conductive third separator, which is joined and whose third peripheral edge is joined to the terminal member, is provided, and the third separator is attached to the terminal member and the specific interconnector. , Each may be joined by welding.

In this electrochemical reaction cell stack, as described above, since the third separator is joined to the terminal member and the specific interconnector by welding, the presence of the third separator causes the fuel chamber to move to the air chamber. The leak of gas can be suppressed, and thus the airtightness of each gas chamber between the air chamber and the fuel chamber can be improved.

Further, in the terminal member and the specific interconnector, a coating film (for example, an alumina coating film or a chromia coating film) may be formed on the surface thereof, respectively. Since the coating has higher electrical resistance than the terminal member or specific interconnector, the electrical connectivity between the terminal member or specific interconnector and the third separator is reduced, resulting in the electrical electrical of the electrochemical reaction cell stack. Performance may deteriorate. In this electrochemical reaction cell stack, since the third separator is joined to the terminal member and the specific interconnector by welding, the third separator and the terminal member, and the third separator and the specific interconnector are connected to each other. , Each are well connected electrically through the welded parts. Therefore, according to the present electrochemical reaction cell stack, the electrical performance of the electrochemical reaction cell stack can be improved more effectively.

The techniques disclosed in the present specification can be realized in various forms, for example, an electrochemical reaction cell stack (fuel cell stack or electrolytic cell stack), an electrochemical reaction cell stack including an electrochemical reaction cell stack. It can be realized in the form of a reaction system (fuel cell system or electrolytic cell system), their operation method, control method, and the like.

It is a perspective view which shows the appearance structure of the fuel cell stack 100 in 1st 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 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 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 enlarges and shows the XZ cross-sectional structure of the part (Px part of FIG. 4) of the 1st separator 120 and the 2nd separator 180 in 1st Embodiment. It is explanatory drawing which enlarges and shows the XZ cross-sectional structure of a part of the 1st separator 120a in the modification. It is explanatory drawing which enlarges and shows the XZ cross-sectional structure of a part of the fuel cell stack 100b in 2nd Embodiment. It is explanatory drawing which enlarges and shows the XZ cross-sectional structure of a part of the fuel cell stack 100c in 3rd Embodiment. It is explanatory drawing which enlarges and shows the YZ cross-sectional structure of a part of the fuel cell stack 100c in 3rd Embodiment.

A. First 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 according to the first embodiment, and FIG. 2 is an XZ cross section of the fuel cell stack 100 at the position II-II of FIG. 1 (and FIG. 6 described later). It is explanatory drawing which shows the structure, and FIG. 3 is an 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. 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. Further, in the present specification, the direction orthogonal to the Z axis is referred to as a plane direction. The plane direction corresponds to the second 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 the present embodiment). The pair of end plates 104 and 106 are arranged so as to sandwich an aggregate (hereinafter, referred to as "cell block 103") composed of seven power generation units 102 from above and below. The arrangement direction (vertical direction) corresponds to the first direction in the claims, and the cell block 103 corresponds to the electrochemical reaction block in the claims.

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 the 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 forming 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 forming 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 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 opposite 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 oxidizer off-gas 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. 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).

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

The fuel cell stack 100 is provided with four gas passage members 27. Each gas passage member 27 has a hollow tubular main body 28 and a hollow tubular branch 29 branched from the side surface of the main body 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 arranged above the power generation unit 102 located at the top, and the other end plate 106 is arranged below the power generation unit 102 located at the bottom. A plurality of power generation units 102 are held in a pressed state by a pair of end plates 104 and 106. 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. The pair of end plates 104 and 106 correspond to a pair of end members within the scope of the claims.

(Structure of power generation unit 102)
FIG. 4 is an explanatory view 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 an XZ cross-sectional configuration 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 view showing an XY cross-sectional configuration of the power generation unit 102 at the position of VI-VI in FIG.

As shown in FIGS. 4 and 5, the power generation unit 102 includes a single cell 110, a first separator 120, an air pole side frame 130, an air pole side current collector 134, and a fuel pole side frame 140. It includes a current collector 144 on the fuel electrode side, a pair of interconnectors 150 constituting the uppermost layer and the lowermost layer of the power generation unit 102, and a second separator 180. Holes corresponding to the communication holes 108 through which the above-mentioned bolts 22 are inserted are formed on the peripheral edges of the first separator 120, the air electrode side frame 130, the fuel electrode side frame 140, and the second separator 180 around the Z axis. Has been done. As described above, since the fuel cell stack 100 includes a plurality of (seven in the present embodiment) power generation units 102, the fuel cell stack 100 includes a plurality of (seven in the present embodiment) single cells. It can be said that it has 110.

The interconnector 150 is a substantially rectangular flat plate-shaped conductive member, and is made of, for example, ferritic stainless steel. The interconnector 150 ensures electrical continuity between the power generation units 102 and prevents mixing of reaction gases between the power generation units 102. In the present embodiment, when two power generation units 102 are arranged adjacent to each other, one interconnector 150 is shared by two adjacent power generation units 102. That is, the upper interconnector 150 in a certain power generation unit 102 is the same member as the lower interconnector 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 150 and is located at the bottom. The power generation unit 102 does not include the lower interconnector 150 (see FIGS. 2 and 3).

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 in between. 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 that is substantially rectangular in the Z-axis direction, and is a dense layer. The electrolyte layer 112 is formed of solid oxides such as YSZ (yttria-stabilized zirconia), ScSZ (scandia-stabilized zirconia), SDC (samarium-doped ceria), GDC (gadolinium-doped ceria), and perovskite-type oxides. There is. As described above, the single cell 110 of the present embodiment is a solid oxide fuel cell (SOFC) that uses a solid oxide as an electrolyte. The air electrode 114 is a substantially rectangular flat plate-shaped member smaller than the electrolyte layer 112 in the Z-axis 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 Z-axis 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 first 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, for example, metal. As shown in FIG. 6, the portion of the first separator 120 that surrounds the first separator through hole 121 (hereinafter, referred to as “first through hole peripheral portion 122”) is one side (hereinafter, referred to as “first through hole peripheral portion 122”) in the vertical direction of the single cell 110. It faces the peripheral edge of the surface (upper side in the drawing). In the present embodiment, since the size of the air electrode 114 in the Z-axis direction is smaller than that of the electrolyte layer 112, the peripheral portion 122 of the first through hole in the first separator 120 is the upper surface of the single cell 110. Among them, it faces the surface composed of the electrolyte layer 112. The first separator 120 is bonded to the single cell 110 (electrolyte layer 112) by a bonding portion 124 formed of a brazing material (for example, Ag wax) arranged at the opposite portion thereof. The first separator 120 partitions the air chamber 166 facing the air pole 114 and the fuel chamber 176 facing the fuel pole 116.

The second separator 180 is a frame-shaped member in which a substantially rectangular second separator through hole 181 penetrating in the vertical direction is formed near the center, and is made of, for example, metal. Similar to the first separator 120, the portion of the second separator 180 surrounding the second separator through hole 181 (hereinafter, referred to as “second through hole peripheral portion 182”) is one of the vertical directions of the interconnector 150. It faces the peripheral edge of the surface on the side (upper side in the drawing). The second separator 180 is joined to the peripheral edge portion of the interconnector 150 by welding. The second 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 150. Gas leakage is suppressed.

The air electrode side frame 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 formed of, for example, an insulator such as mica. The air chamber hole 131 of the air electrode side frame 130 constitutes an air chamber 166 facing the air electrode 114. The air electrode side frame 130 is formed on the first peripheral edge of the surface of the first separator 120 opposite to the side facing the electrolyte layer 112 and the surface of the second separator 180 on the side facing the air electrode 114. It is in contact with the second peripheral edge. That is, the air electrode side frame 130 is sandwiched between the first separator 120 and the second separator 180. Therefore, the air electrode side frame 130 realizes a seal (compression seal) of the air chamber 166. Further, the air electrode side frame 130 electrically insulates between the pair of interconnectors 150 and the second separator 180 included in the power generation unit 102. Further, in the air electrode side frame 130, the oxidant gas supply communication flow path 132 that communicates the oxidant gas introduction manifold 161 and the air chamber 166, and the oxidant that communicates the air chamber 166 and the oxidant gas discharge manifold 162. A gas discharge communication flow path 133 is formed. The air pole side frame 130 corresponds to the air pole side frame member in the claims, and the air chamber hole 131 corresponds to the air pole side frame through hole in the claims.

The fuel electrode side frame 140 is a frame-shaped member in which a substantially rectangular fuel chamber hole 141 penetrating in the vertical direction is formed near the center, and is formed of, for example, metal. The fuel electrode side frame 140 has a first peripheral edge portion of the surface of the first separator 120 facing the electrolyte layer 112 and a second peripheral edge portion of the surface of the second separator 180 facing the fuel electrode 116. It is in contact with the portion (see FIGS. 4 and 5). The fuel pole side frame 140 corresponds to the fuel pole side frame member in the claims, and the fuel chamber hole 141 corresponds to the fuel pole side frame through hole in the claims.

As shown in FIG. 6, 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 electrode side current collector 134 is in contact with the surface of the air electrode 114 opposite to the side facing the electrolyte layer 112 and the surface of the interconnector 150 on the side facing the air electrode 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 150, the air electrode side current collector 134 in the power generation unit 102 is the uppermost first stage. It is in contact with the separator 180 of 2, and is electrically connected to the upper end plate 104 via the second separator 180. Since the air electrode side current collector 134 has such a configuration, the air electrode 114 and the interconnector 150 (or the end plate 104) are electrically connected. 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. It may be intervening. Further, the air electrode side current collector 134 may be configured as a member integrated with the interconnector 150.

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 pole 116 opposite to the side facing the electrolyte layer 112, and the interconnector facing portion 146 is on the surface of the interconnector 150 facing the fuel pole 116. Are in contact. 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 150, the interconnector facing portion 146 in the power generation unit 102 is an intermediate member 190 described later. Is in contact with, and is electrically connected to the lower end plate 106 via the intermediate member 190. Since the fuel pole side current collector 144 has such a configuration, the fuel pole 116 and the interconnector 150 (or the end plate 106) are electrically connected to each other. A spacer 149 formed of, for example, 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 150 (or the end plate 106) via the fuel electrode side current collector 144 follow. Good electrical connection with is maintained.

A-2. Operation of fuel cell stack 100:
As shown in FIGS. 2, 4 and 6, the oxidant gas is passed 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. When the OG is supplied, 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 each power generation unit is supplied from the oxidizer gas introduction manifold 161. It is supplied to the air chamber 166 via the oxidizing agent gas supply communication flow path 132 of 102. 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 the 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 interconnectors 150 via the air pole side current collector 134, and the fuel pole 116 is via the fuel pole side current collector 144. It is electrically connected to the other interconnector 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. (Not shown) may be heated.

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 as shown in FIGS. 2, 4 and 6. Further, through the holes of the main body 28 and the branch 29 of the gas passage member 27 provided at the position of the oxidant gas discharge manifold 162, and through the gas pipe (not shown) connected to the branch 29. It is discharged to the outside of the fuel cell stack 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 fuel. The outside of the fuel cell stack 100 via the holes of the main body 28 and the branch 29 of the gas passage member 27 provided at the position of the gas discharge manifold 172, and the gas pipe (not shown) connected to the branch 29. Is discharged to.

A-3. Relationship between single cell 110 and frames 130, 140 and pair of end plates 104, 106 in cell block 103:
As shown in FIGS. 1 to 3, in the fuel cell stack 100 of the present embodiment, opening windows 104A and 106A penetrating in the vertical direction (arrangement direction of the single cells 110) are formed in the end plates 104 and 106. ing. That is, spaces S1 and S2 that are opened on both the upper and lower sides (the cell block 103 side and the side opposite to the cell block 103) are formed in the end plates 104 and 106 by the opening windows 104A and 106A. In the vertical view, the contour lines of the spaces S1 and S2 include the single cell 110. In other words, the contour lines of the spaces S1 and S2 are located outside the outline of the single cell 110 over the entire circumference. In the vertical view, the end plates 104 and 106 do not overlap the cell block 103 but overlap the frames 130 and 140.

An intermediate member 190 is arranged between the cell block 103 and the lower end plate 106. The intermediate member 190 is a flat plate-like member having no through hole formed, and is formed of, for example, metal. A fuel pole side current collector 144 located at the lowermost position of the cell block 103 is joined to the vicinity of the center of the intermediate member 190, and the peripheral edge of the intermediate member 190 is formed by the cell block 103 and the lower end plate 106. It is sandwiched between. That is, the cell block 103 is supported by the first separator 120, the second separator 180, and the intermediate member 190 for each of the frames 130 and 140. The thickness of the first separator 120, the second separator 180, and the intermediate member 190 in the vertical direction is thinner than the vertical thickness of the frames 130 and 140, and is smaller than that of the frames 130 and 140. Highly flexible.

With the above configuration, the fuel cell stack 100 includes a plurality of fastening members (bolts 22 and nuts 24), and the plurality of fastening members extend over the pair of end plates 104 and 106 and the frames 130 and 140 in the cell block 103. It is inserted into each of the plurality of communication holes 108 formed, and the fuel cell stack 100 is fastened by the plurality of fastening members. Specifically, the portion of the fuel cell stack 100 (cell block 103) that overlaps the end plates 104 and 106 in the vertical direction (mainly the frames 130 and 140) is sandwiched between the pair of end plates 104 and 106. , Receives a relatively large load due to the fastening force of the fastening members (bolts 22 and nuts 24) that fasten the pair of end plates 104 and 106. As a result, the frames 130 and 140 realize the sealing of the air chamber 166 and the fuel chamber 176. On the other hand, in the fuel cell stack 100, the portion (mainly the single cell 110) that does not overlap with the end plates 104 and 106 in the vertical direction directly applies the load due to the fastening force of the fastening member that fastens the pair of end plates 104 and 106. I don't receive it. That is, the single cell 110 and the frames 130 and 140 in the fuel cell stack 100 have different amounts of loads received from the pair of end plates 104 and 106 in the vertical direction. As a result, the frames 130 and 140 are subjected to a relatively large load necessary for realizing the sealing of the air chamber 166 and the fuel chamber 176, and the single cell 110 is provided with the conductivity between the single cells 110. It is possible to prevent an unnecessarily large load from being applied while ensuring the above.

A-4. Detailed configuration of the first separator 120:
FIG. 7 is an explanatory view showing an enlarged XZ cross-sectional configuration of a part (Px portion of FIG. 4) of the first separator 120 and the second separator 180. The vertical thickness (for example, 0.1 mm) of the first separator 120 is thinner than the vertical thickness (for example, 1 mm) of each of the frames 130 and 140. The first separator 120 corresponds to the first flexible member in the claims, and the second separator 180 corresponds to the second flexible member in the claims.

The first separator 120 includes a first inner portion 126 including a first through hole peripheral portion 122, and a first outer portion 127 located on the outer peripheral side of the first inner portion 126. The positions of the first inner portion 126 and the first outer portion 127 in the Z-axis direction are substantially the same as each other. The position of the first inner portion 126 in the Z-axis direction is the position of the first inner portion 126 on the side (upper side) of the surface of the first inner portion 126 facing the air chamber 166. It means the position of the highest part in. The position of the first outer portion 127 in the Z-axis direction is the most on the surface of the first outer portion 127 on the side (upper side) facing the air chamber 166 in the surface of the first outer portion 127. It means the position of the part located above. The first inner portion 126 corresponds to the inner portion in the claims, and the first outer portion 127 corresponds to the outer portion in the claims.

The first separator 120 further includes a first connecting portion 128 that connects the end of the first inner portion 126 and the end of the first outer portion 127. In the present embodiment, the first connecting portion 128 has a curved shape so as to project from the positions of the first inner portion 126 and the first outer portion 127 toward the fuel chamber 176 side (lower side). .. That is, the fuel chamber 176 side (lower side) of the first connecting portion 128 is a convex portion, and the air chamber 166 side (upper side) of the first connecting portion 128 is a concave portion. As described above, the first connecting portion 128 includes a portion whose position in the Z-axis direction is different from that of the first inner portion 126 and the first outer portion 127. The first connecting portion 128 is formed so as to surround the first separator through hole 121 in the Z-axis direction. Further, the first connecting portion 128 in the first separator 120 is formed by, for example, press working. Since the first connecting portion 128 of the first separator 120 has the above-described configuration, it functions like a spring that easily expands and contracts in the plane direction. Therefore, the first separator 120 of the present embodiment is more likely to be deformed in the plane direction at the position of the first connecting portion 128 as compared with the configuration not provided with the first connecting portion 128. Further, the thickness t ₁ (plate thickness) of the first separator 120 in the vertical direction may be 0.01 (mm) or more, and is preferably 0.03 (from the viewpoint of suppressing a decrease in oxidation resistance). mm) or more, more preferably 0.05 (mm) or more, and preferably 0.2 (mm) or less. By setting the thickness t ₁ of the first separator 120 to 0.03 (mm) or more, it is possible to suppress a decrease in the oxidation resistance of the first separator 120, and the thickness t of the first separator 120 _By setting ₁ to 0.2 (mm) or less, the springiness of the first connecting portion 128 can be ensured to a certain degree or more.

As shown in FIG. 7, the depth H1 of the _first connecting portion is more preferably 0.1 (mm) or more and 2.0 (mm) or less. By setting the depth H ₁ of the first connecting portion to 0.1 (mm) or more, the effect of suppressing deformation or cracking of the single cell 110 by the first connecting portion 128 can be ensured. Further, when the depth H _{1 of} the first connecting portion is higher than 2.0 (mm), the gas flow is obstructed by the first connecting portion 128, which may reduce the power generation performance, which is not preferable. By setting the depth H 1 of the connecting portion ₁ to 2.0 (mm) or less, it is possible to prevent the first connecting portion 128 from obstructing the gas flow and deteriorating the power generation performance.

Further, it is preferable that the depth H ₁ of the first connecting portion is larger than the thickness t ₁ of the first separator 120. By making the depth H ₁ of the first connecting portion larger than the thickness t ₁ of the first separator 120, it is possible to secure the effect of suppressing the deformation and cracking of the single cell 110 by the first connecting portion 128. .. The first connecting portion 128 corresponds to the connecting portion within the scope of the claims.

Further, in FIG. 6, in the vertical view, the region within the contour lines of the opening windows 104A and 106A formed in the end plates 104 and 106 is formed by two diagonal lines (virtual straight lines) of the contour lines (rectangles). The first to fourth compartment areas E1 to E4 formed by dividing into four equal parts are shown. In the present embodiment, the first separator 120 is formed so that the first connecting portion 128 is located in all the regions of the first to fourth compartment regions E1 to E4. Specifically, in the first separator 120, a first connecting portion 128 is continuously formed along the first peripheral edge portion of the first separator 120 over the entire circumference. The shapes of the opening windows 104A and 106A formed on the end plates 104 and 106 are not limited to rectangles, and may be, for example, circular.

Further, the first separator 120 further satisfies the following first requirement in all cross sections that pass through the center O of the single cell 110 in the vertical direction (Z-axis direction) and are parallel to the vertical direction. (See Fig. 7). In the same cross section, the direction (X-axis direction) orthogonal to the vertical direction (Z-axis direction) corresponds to the third direction in the claims.
<First requirement>
"First distance ΔX1">"Second distance ΔZ1"
First distance ΔX1: Distance between the single cell 110 and the air electrode side frame 130 (a frame located on the same side as the single cell 110 with respect to the first separator 120 in the vertical direction) in the vertical direction. ΔZ1: Of the first separator 120, the vertical distance between the cell-side joining portion 123 joined to the single cell 110 and the frame-side joining portion 129 joined to the air electrode side frame 130. The joint portion 129 corresponds to the air pole side frame side joint portion in the claims.

Further, the first separator 120 further satisfies the following second requirement in all the cross sections that pass through the center O of the single cell 110 in the vertical direction (Z-axis direction) and are parallel to the vertical direction. (See Fig. 7).
<Second requirement>
"Length ΔC1 of the first connecting portion 128">"Minimum distance ΔB1 between the cell side joining portion 123 and the frame side joining portion 129"-"First distance ΔX1"
Length of the first connecting portion 128 ΔC1: The shortest distance between the first inner portion 126 and the first outer portion 127 on the inner peripheral surface of the first connecting portion 128 Cell-side joint portion 123 and the frame. It is a value obtained by dividing the first distance ΔX1 from the square root of the shortest distance ΔB1: [(first distance ΔX1) ² + (second distance ΔZ1) ² ] with the side joint portion 129.

Further, the first separator 120 further satisfies the following third requirement in all the cross sections that pass through the center O of the single cell 110 in the vertical direction (Z-axis direction) and are parallel to the vertical direction. (See Fig. 7).
<Third requirement>
"Second distance ΔZ1"> 0.01 mm

A-5. Detailed configuration of the second separator 180:
The second separator 180 includes a second inner portion 186 including a second through hole peripheral portion 182, and a second outer portion 187 located on the outer peripheral side of the second inner portion 186. The positions of the second inner portion 186 and the second outer portion 187 in the Z-axis direction are substantially the same as each other. The position of the second inner portion 186 in the Z-axis direction is the position of the second inner portion 186 on the side (upper side) of the surface of the second inner portion 186 facing the fuel chamber 176. It means the position of the highest part in. The position of the second outer portion 187 in the Z-axis direction is the most on the surface of the second outer portion 187 on the side (upper side) facing the fuel chamber 176 in the surface of the second outer portion 187. It means the position of the part located above.

The second separator 180 further includes a second connecting portion 188 that connects the end of the second inner portion 186 and the end of the second outer portion 187. In the present embodiment, the second connecting portion 188 has a curved shape so as to project from the positions of the second inner portion 186 and the second outer portion 187 toward the fuel chamber 176 side (lower side). .. That is, the fuel chamber 176 side (lower side) of the second connecting portion 188 is a convex portion, and the air chamber 166 side (upper side) of the second connecting portion 188 is a concave portion. As described above, the second connecting portion 188 includes a portion whose position in the Z-axis direction is different from that of the second inner portion 186 and the second outer portion 187. The second connecting portion 188 is formed so as to surround the second separator through hole 181 in the Z-axis direction. Further, the second connecting portion 188 in the second separator 180 is formed by, for example, press working. Since the second connecting portion 188 of the second separator 180 has the above-described configuration, it functions like a spring that easily expands and contracts in the plane direction. Therefore, the second separator 180 of the present embodiment is more likely to be deformed in the plane direction at the position of the second connecting portion 188 as compared with the configuration not provided with the second connecting portion 188. Further, the thickness t ₂ (plate thickness) of the second separator 180 in the vertical direction may be 0.01 (mm) or more, and is preferably 0.03 (from the viewpoint of suppressing a decrease in oxidation resistance). mm) or more, more preferably 0.05 (mm) or more, and preferably 0.2 (mm) or less. By setting the thickness t ₂ of the second separator 180 to 0.03 (mm) or more, it is possible to suppress a decrease in the oxidation resistance of the second separator 180, and the thickness t of the second separator 180. _By setting ₂ to 0.2 (mm) or less, the springiness of the second connecting portion 188 can be ensured to a certain degree or more.

As shown in FIG. 7, the depth H ₂ of the second connecting portion is more preferably 0.1 (mm) or more and 2.0 (mm) or less. By setting the depth H ₂ of the second connecting portion to 0.1 (mm) or more, the effect of suppressing deformation or cracking of the single cell 110 by the second connecting portion 188 can be ensured. Further, if the depth H _{2 of} the second connecting portion is higher than 2.0 (mm), the gas flow is obstructed by the second connecting portion 188, which may reduce the power generation performance, which is not preferable. By setting the depth H 2 of the connecting portion ₂ to 2.0 (mm) or less, it is possible to prevent the second connecting portion 188 from obstructing the gas flow and deteriorating the power generation performance.

Further, the depth H ₂ of the second connecting portion is preferably larger than the thickness t ₂ of the second separator 180. By making the depth H ₂ of the second connecting portion larger than the thickness t ₂ of the second separator 180, the effect of suppressing the deformation and cracking of the single cell 110 by the second connecting portion 188 can be ensured. ..

Further, in the present embodiment, similarly to the first separator 120 described above, in the second separator 180, the second connecting portion 188 is located in all the regions of the first to fourth compartment regions E1 to E4. It is formed like this. Specifically, in the second separator 180, a second connecting portion 188 is continuously formed over the entire circumference along the second peripheral edge portion of the second separator 180.

Further, the second separator 180 passes through the center O of the single cell 110 in the vertical direction (Z-axis direction) and further satisfies the following fourth requirement in all cross sections parallel to the vertical direction. (See Fig. 7).
<Fourth requirement>
"First distance ΔX2">"Second distance ΔZ2"
First distance ΔX2: Distance between the single cell 110 and the air electrode side frame 130 (a frame located on the same side as the single cell 110 with respect to the second separator 180 in the vertical direction) in the vertical direction. ΔZ2: Of the second separator 180, the vertical distance between the connector-side joint 183 joined to the interconnector 150 and the frame-side joint 189 joined to the fuel electrode-side frame 140. The joint portion 189 corresponds to the fuel pole side frame side joint portion in the claims.

Further, the second separator 180 passes through the center O of the single cell 110 in the vertical direction (Z-axis direction) and further satisfies the following fifth requirement in all cross sections parallel to the vertical direction. (See Fig. 7).
<Fifth requirement>
"Length ΔC2 of the second connecting portion 188">"Minimum distance ΔB2 between the connector side joint portion 183 and the frame side joint portion 189"-"First distance ΔX2"
Length ΔC2 of the second connecting portion 188: The shortest distance between the second inner portion 186 and the second outer portion 187 on the inner peripheral surface of the second connecting portion 188 The connector side joint portion 183 and the frame. The shortest distance ΔB2 to the side joint 189: [(first distance ΔX2) ² + (second distance ΔZ2) ² ] is the value obtained by dividing the first distance ΔX2 from the square root.

Further, the second separator 180 passes through the center O of the single cell 110 in the vertical direction (Z-axis direction) and further satisfies the following sixth requirement in all cross sections parallel to the vertical direction. (See Fig. 7).
<Sixth requirement>
"Second distance ΔZ2"> 0.01 mm

A-6. Effect of the first embodiment:
As described above, in the fuel cell stack 100 of the present embodiment, the space S1 is formed in the end plates 104 and 106. The space S1 is open at least on the cell block 103 side, and the contour line includes the single cell 110 in the vertical view, which is the direction in which the plurality of power generation units 102 (single cell 110) are lined up. In the fuel cell stack 100 in which the space S1 is formed in the end plates 104 and 106 in this way, for example, no space is formed in the end plates 104 and 106, and the entire surface of the end plates 104 and 106 on the cell block 103 side is the entire surface. Compared to the configuration in which the cells are flat, the frames 130, 140 and the single cell 110 in the cell block 103 are simply different from the end plates 104, 106 due to the different loads received from the pair of end plates 104, 106. A displacement difference in the vertical direction with the cell 110 (displacement difference in the vertical direction between the cell-side joint portion 123 and the frame-side joint portion 129 shown in FIG. 7) is likely to occur. Then, for example, due to a heat cycle, heat shock, or the like, the displacement difference between the end plates 104, 106 and the single cell 110 in the vertical direction becomes even larger. When a displacement difference between the end plates 104 and 106 and the single cell 110 occurs in the vertical direction, for example, the single cell 110 is pulled in the vertical direction via the first separator 120, so that the single cell 110 is cracked. In addition, the performance of the fuel cell stack 100 may deteriorate, for example, the sealing performance of the end plates 104 and 106 may deteriorate.

On the other hand, according to the fuel cell stack 100 of the present embodiment, the first connecting portion 128 of the first separator 120 functions like a spring that easily expands and contracts, and the first separator 120 is the first. Since it is easily deformed at the position of the connecting portion 128 (see FIG. 7), when the displacement difference between the end plates 104 and 106 and the single cell 110 in the vertical direction becomes large, the first separator 120 mainly becomes the first connecting portion 128. As a result, the stress generated in the single cell 110 and the end plates 104 and 106 is relaxed due to the above displacement difference, so that the displacement of the end plates 104 and 106 and the single cell 110 in the vertical direction is relaxed. It is possible to suppress the deterioration of the performance of the fuel cell stack 100 due to the difference.

Further, in the present embodiment, the first separator 120 is formed so that the first connecting portion 128 is located in all the regions of the first to fourth compartment regions E1 to E4 (see FIG. 6). ). Therefore, according to the present embodiment, the function of stress relaxation is exerted over the entire circumference of the first separator 120. Therefore, for example, the first connection is made to any of the first to fourth partition regions E1 to E4. Compared with the configuration in which the portion 128 is not formed, the deterioration of the performance of the fuel cell stack 100 due to the displacement difference between the end plates 104 and 106 and the single cell 110 in the vertical direction can be more effectively suppressed. ..

Further, in the present embodiment, the first distance ΔX1, which is the distance between the single cell 110 joined to the first separator 120 and the frames 130, 140 in the vertical direction, is the cell side joining in the first separator 120. It is longer than the second distance ΔZ1, which is the vertical distance between the portion 123 and the frame-side joint portion 129 (see the first requirement FIG. 7 above). Here, FIG. 8 is an explanatory view showing an enlarged XZ cross-sectional structure of a part of the first separator 120a in the modified example. In the fuel cell stack 100a of the modified example, the first distance ΔX1 is equal to or less than the second distance ΔZa (> ΔZ1). Therefore, the second inclination (angle θ1a> above angle θ1) of the first separator 120a with respect to the surface direction becomes relatively steep, and as a result, the stress in the vertical direction generated in the single cell 110 and the frames 130 and 140 becomes relatively steep. Is relatively large. On the other hand, according to the present embodiment, the inclination of the first separator 120 with respect to the plane direction (see angle θ1) under the condition that the second distance ΔZa is the same as that of the fuel cell stack 100a of the modified example. ) Is relatively gentle, and as a result, the stress generated in the single cell and the frame member in the first direction is small. Therefore, according to the present embodiment, it is possible to more effectively suppress the deterioration of the performance of the fuel cell stack 100 due to the vertical displacement difference between the end plates 104 and 106 and the single cell 110.

In the present embodiment, the length ΔC1 of the first connecting portion 128 in the first separator 120 is the first from the shortest distance ΔB1 between the cell-side joint portion 123 and the frame-side joint portion 129 in the first separator 120. It is longer than the length obtained by subtracting the distance ΔX1 (see FIG. 7). Therefore, according to the present embodiment, the frames 130, 140 and the single cell have a length ΔC1 of the first connecting portion 128 shorter than the length obtained by subtracting the first distance ΔX1 from the shortest distance ΔB1. The stress generated in the single cell 110 and the frames 130 and 140 due to the displacement difference in the vertical direction from the 110 can be effectively relieved by the extension of the first connecting portion 128 of the first separator 120.

Further, according to the present embodiment, in a configuration in which the second distance ΔZ1, which is the vertical distance between the cell-side joint portion 123 and the frame-side joint portion 129 in the first separator 120, is larger than 0.01 mm. Especially effective.

B. Second embodiment:
FIG. 9 is an enlarged explanatory view showing an XZ cross-sectional configuration of a part of the fuel cell stack 100b according to the second embodiment. FIG. 9 shows an enlarged configuration of a portion equivalent to the Px portion shown in FIG. 4 in the configuration of the fuel cell stack 100b of the second embodiment. In the following, among the configurations of the fuel cell stack 100b of the second embodiment, the configurations equivalent to the configurations of the fuel cell stack 100 of the first embodiment described above will be appropriately omitted by adding the same reference numerals. ..

As shown in FIG. 9, in the fuel cell stack 100b of the second embodiment, the second separator 180 is first joined to the interconnector 150 and the fuel electrode side frame 140 by welding, respectively. It is different from the fuel cell stack 100 of the embodiment.

Specifically, in the present embodiment, the second through-hole peripheral portion 182 of the second separator 180 is joined to the upper surface of the peripheral portion of the interconnector 150 by laser welding. In other words, a welded portion 232 that joins the second separator 180 and the interconnector 150 is formed at a position where the second separator 180 and the interconnector 150 come into contact with each other. A part of the welded portion 232 is exposed on the upper surface of the welded member (second separator 180), and a part of the welded portion 232 penetrates into the member to be welded (interconnector 150). In the present embodiment, the welded portion 232 is continuously formed on the peripheral portion 182 of the second through hole of the second separator 180 and the peripheral edge portion of the interconnector 150 in the Z-axis direction. Further, in the present embodiment, the second outer portion 187 of the second separator 180 (more specifically, a part of the second outer portion 187 and the second peripheral edge portion of the second separator 180) is , It is joined to the lower surface of the fuel electrode side frame 140 by laser welding. In other words, a welded portion 231 that joins the second separator 180 and the fuel pole side frame 140 is formed at a position where the second separator 180 and the fuel pole side frame 140 are in contact with each other. A part of the welded portion 231 is exposed on the lower surface of the welded member (second separator 180), and a part of the welded portion 231 penetrates into the member to be welded (fuel electrode side frame 140). .. In the present embodiment, the welded portion 231 is continuously formed in the second peripheral edge portion of the second separator 180 and the peripheral portion of the fuel chamber hole 141 of the fuel electrode side frame 140 in the Z-axis direction. ..

In the present embodiment, similarly to the second outer portion 187 of the second separator 180, the first outer portion 127 of the first separator 120 (more specifically, a part of the first outer portion 127). , The first peripheral edge of the first separator 120) is joined to the upper surface of the fuel electrode side frame 140 by laser welding. In other words, a welded portion 241 that joins the first separator 120 and the fuel electrode side frame 140 is formed at a position where the first separator 120 and the fuel electrode side frame 140 are in contact with each other. A part of the welded portion 241 is exposed on the upper surface of the welded member (first separator 120), and a part of the welded portion 241 has penetrated into the member to be welded (fuel electrode side frame 140). Therefore, the leakage of gas from the fuel chamber 176 to the air chamber 166 at the first peripheral edge of the first separator 120 is suppressed. In the present embodiment, the welded portion 241 is continuously formed in the first peripheral portion of the first separator 120 and the peripheral portion of the fuel chamber hole 141 of the fuel pole side frame 140 in the Z-axis direction. .. Therefore, the airtightness in each gas chamber with the air chambers 166 and 176 can be improved.

In the fuel cell stack 100b of the present embodiment, as described above, the welded portion 231 that joins the fuel electrode side frame 140 and the second separator 180 is the lower surface of the fuel electrode side frame 140 from the second separator 180. It is formed so as to penetrate the inside of the fuel electrode side frame 140. Further, a welded portion 232 for joining the interconnector 150 and the second separator 180 is formed so as to penetrate the upper surface of the interconnector 150 from the second separator 180 and reach the inside of the interconnector 150. Therefore, the leakage of gas from the fuel chamber 176 to the air chamber 166 at the second through-hole peripheral portion 182 and the second peripheral edge portion of the second separator 180 is suppressed, and as a result, the air chamber 166 and the fuel chamber 176 It is possible to improve the airtightness in each gas chamber.

C. Third Embodiment:
10 and 11 are explanatory views showing an enlarged XZ cross-sectional structure and a YZ cross-sectional structure of a part of the fuel cell stack 100c according to the third embodiment, respectively. FIG. 10 shows the configuration of the fuel cell stack 100c according to the third embodiment at the same position as the cross section shown in FIG. FIG. 11 shows the configuration of the fuel cell stack 100c according to the third embodiment at the same position as the cross section shown in FIG. In the following, among the configurations of the fuel cell stack 100c of the third embodiment, the same reference numerals are given to the configurations equivalent to the configurations of the fuel cell stacks 100 and 100b of the first embodiment and the second embodiment described above. The description thereof will be omitted as appropriate.

As shown in FIGS. 10 and 11, the fuel cell stack 100c of the third embodiment is mainly provided with a pair of terminal plates 70 and 80 and a pair of insulating sheets 92 and 94. 2 Different from the fuel cell stack 100b of the embodiment.

One of the pair of terminal plates 70 and 80 (hereinafter referred to as "upper terminal plate 70") is arranged between the upper end plate 104 and the cell block 103 in the Z-axis direction, and is a pair of insulation. One of the sheets 92 and 94 (hereinafter, referred to as “upper insulating sheet 92”) is arranged above the upper terminal plate 70. That is, the upper end plate 104 is arranged above the upper insulating sheet 92. Further, the other of the pair of terminal plates 70 and 80 (hereinafter, referred to as "lower terminal plate 80") is arranged between the lower end plate 106 and the cell block 103 in the Z-axis direction. , The other of the pair of insulating sheets 92, 94 (hereinafter, referred to as “lower insulating sheet 94”) is arranged on the lower side of the lower terminal plate 80. That is, the lower end plate 106 is arranged below the lower insulating sheet 94.

Similar to the pair of end plates 104, 106, a plurality of terminal plates 70, 80 and the pair of insulating sheets 92, 94 penetrating in the vertical direction on the peripheral edge portion around the Z-axis direction (the present embodiment). 8) holes are formed. Therefore, in the fuel cell stack 100c of the present embodiment, the holes formed in each member and corresponding to each other communicate with each other in the vertical direction, and the communication holes 108 extending in the vertical direction from the upper end plate 104 to the lower end plate 106 are formed. It is configured.

(Structure of Insulation Sheets 92 and 94)
The pair of insulating sheets 92 and 94 are flat plate-shaped members having a substantially rectangular outer shape in the Z-axis direction, and are, for example, mica sheets, ceramic fiber sheets, ceramic dust sheets, glass sheets, glass-ceramic composite agents, and the like. It is composed of an insulating material. A hole 93 that communicates with the hole 32 of the upper end plate 104 and penetrates in the Z-axis direction is formed near the center of the upper insulating sheet 92. In the Z-axis direction, the inner peripheral line of the hole 93 formed in the upper insulating sheet 92 includes each single cell 110. In the present embodiment, the inner peripheral line of the hole 93 formed in the upper insulating sheet 92 substantially coincides with the inner peripheral line of the hole 32 formed in the upper end plate 104 in the Z-axis direction. The upper end plate 104 corresponds to the first end member in the claims. The upper insulating sheet 92 corresponds to the insulating member in the claims, and the hole 93 corresponds to the insulating member through hole in the claims.

(Structure of terminal plates 70 and 80)
The pair of terminal plates 70, 80 are flat plate-shaped members having a substantially rectangular outer shape in the Z-axis direction, and are formed of a conductive material such as stainless steel. A hole 71 penetrating in the Z-axis direction is formed near the center of the upper terminal plate 70. In the Z-axis direction, the inner peripheral line of the hole 71 formed in the upper terminal plate 70 includes each single cell 110. In the present embodiment, the inner peripheral line of the hole 71 formed in the upper terminal plate 70 substantially coincides with the inner peripheral line of the hole 32 formed in the upper end plate 104 in the Z-axis direction. In the fuel cell stack 100c of the present embodiment, the upper terminal plate 70 includes a protruding portion 78 protruding outward from the outer peripheral line of the upper end plate 104 in the Z-axis direction, and the protruding portion 78 is a fuel cell. It functions as an output terminal on the positive side of the stack 100c. Further, the lower terminal plate 80 includes a protruding portion 88 projecting outward from the outer peripheral line of the lower end plate 106 in the Z-axis direction, and the protruding portion 88 is on the minus side of the fuel cell stack 100c. Functions as an output terminal. That is, the upper terminal plate 70 is electrically connected to the interconnector 150 located at the uppermost portion of the cell block 103 (the "topmost interconnector 150X" described later), and the lower terminal plate 80 is the cell block 103. The upper terminal plate 70 corresponds to the terminal member in the claims, and the hole 71 corresponds to the terminal member through hole in the claims, which is electrically connected to the interconnector 150 located at the bottom of the. To do.

The upper interconnector 150 (hereinafter, also referred to as “uppermost interconnector 150X”) of the power generation unit 102 (hereinafter, also referred to as “upper specific power generation unit 102X”) located at the uppermost side of the fuel cell stack 100c is the second It is electrically connected to the upper terminal plate 70 via a separator 180 (hereinafter, also referred to as “top separator 180X”). That is, the upper terminal plate 70 is electrically connected to the cell block 103. Further, the uppermost separator 180X is a frame-shaped member in which a substantially rectangular uppermost separator through hole 181X penetrating in the Z-axis direction is formed in the vicinity of the center, like the second separator 180, and is, for example, made of metal. It is formed. The uppermost interconnector 150X corresponds to a specific interconnector within the scope of claims. The uppermost separator 180X corresponds to the third separator in the claims, and the uppermost separator through hole 181X corresponds to the third separator through hole in the claims.

Further, in the present embodiment, the uppermost separator 180X includes a third inner portion 186X including a third through hole peripheral portion 182X, and a third outer portion 187X located outside the third inner portion 186X. It includes a third connecting portion 188X that connects the end portion of the third inner portion 186X and the end portion of the third outer portion 187X. The configuration of the third inner portion 186X, the third outer portion 187X and the third connecting portion 188X is the same as that of the second inner portion 186, the second outer portion 187 and the second connecting portion, respectively. Similar to the configuration. The third through-hole peripheral portion 182X of the uppermost separator 180X is joined to the upper surface of the peripheral portion of the uppermost interconnector 150X by laser welding. In other words, a welded portion 212 for joining the uppermost separator 180X and the uppermost interconnector 150X is formed at a position where the uppermost separator 180X and the uppermost interconnector 150X are in contact with each other. A part of the welded portion 212 is exposed on the upper surface of the welded member (uppermost separator 180X), and a part of the welded portion 212 penetrates into the member to be welded (uppermost interconnector 150X). In the present embodiment, the welded portion 212 is continuously formed on the peripheral portion of the through hole of the uppermost separator 180X and the peripheral portion of the uppermost interconnector 150X in the Z-axis direction. Further, in the present embodiment, the third peripheral edge portion of the uppermost separator 180X is joined to the lower surface of the upper terminal plate 70 by laser welding. In other words, a welded portion 211 for joining the uppermost separator 180X and the upper terminal plate 70 is formed at a position where the uppermost separator 180X and the upper terminal plate 70 are in contact with each other. A part of the welded portion 211 is exposed on the lower surface of the welded member (uppermost separator 180X), and a part of the welded portion 211 penetrates into the member to be welded (upper terminal plate 70). In the present embodiment, the welded portion 211 is continuously formed in the third peripheral edge portion of the uppermost separator 180X and the peripheral portion of the hole 71 of the upper terminal plate 70 in the Z-axis direction.

In the fuel cell stack 100c of the present embodiment, as described above, the welded portion 211 that joins the upper terminal plate 70 and the uppermost separator 180X penetrates the lower surface of the upper terminal plate 70 from the uppermost separator 180X and is upper. It is formed so as to reach the inside of the terminal plate 70. Further, the welded portion 212 that joins the uppermost interconnector 150X and the uppermost separator 180X is formed so as to penetrate the upper surface of the uppermost interconnector 150X from the uppermost separator 180X and reach the inside of the uppermost interconnector 150X. Has been done. Therefore, the leakage of gas from the air chamber 166 to the outside of the fuel cell stack 100c at the third through-hole peripheral portion 182X and the third peripheral edge portion of the uppermost separator 180X is suppressed, and by extension, the airtightness in the air chamber 166 is suppressed. Can be improved.

Further, in the upper terminal plate 70 and the uppermost interconnector 150X, a coating film (for example, an alumina coating film or a chromia coating film) may be formed on the surfaces thereof, respectively. Since the coating has a higher electrical resistance than the upper terminal plate 70 or the uppermost interconnector 150X, the electrical connectivity between the upper terminal plate 70 or the uppermost interconnector 150X and the uppermost separator 180X is reduced, resulting in reduced electrical connectivity. The electrical performance of the fuel cell stack may deteriorate. In the fuel cell stack 100c of the present embodiment, as described above, the welded portion 211 that joins the upper terminal plate 70 and the uppermost separator 180X, and the welded portion 212 that joins the uppermost interconnector 150X and the uppermost separator 180X. Is formed, so that the uppermost interconnector 150X and the upper terminal plate 70 are electrically well connected via the welded portions 211 and 212. Therefore, according to the fuel cell stack 100c, the electrical performance of the fuel cell stack 100c can be improved more effectively.

D. 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. For example, the following modifications are also possible.

The configuration of the single cell 110, the power generation unit 102, or the fuel cell stack 100 in the above embodiment is merely an example and can be variously modified. For example, in the above embodiment, a space may be formed in only one of the pair of end plates 104 and 106. Further, in the above embodiment, the spaces S1 and S2 penetrating the end plates 104 and 106 are exemplified as the space, but the space is opened, for example, on the cell block 103 side and on the opposite side of the cell block 103. It may be a concave space that is not provided. Further, in the above embodiment, the flat plate-shaped end plates 104 and 106 are exemplified as the end member, but the end member may have a shape other than the flat plate shape. Further, in the above embodiment, the shape of the end member in the vertical direction is a frame shape, but for example, in the above embodiment, the shapes of the end plates 104 and 106 are formed on the outer circumference of the fuel cell stack 100 around the Z axis. A portion along each of the three sides (for example, a portion fastened by seven bolts 22 excluding any one of the bolts 22A, 22B, 22D, 22E) and a portion along the remaining one side. The shape may not be provided, or six bolts except for one set of bolts 22A and 22B or bolts 22D and 22E along two parallel sides of the outer circumference of the fuel cell stack 100 around the Z axis. It may have a shape having a portion to be fastened at 22) and not having a portion along the remaining two sides.

Further, in the above embodiment, the intermediate member 190 may have a structure in which a through hole is formed.

Further, in the above embodiment, all the first separators 120 provided in the fuel cell stack 100 are provided with the first connecting portion 128, but all the first separators 120 provided in the fuel cell stack 100 are provided. If at least one of the above is provided with the first connecting portion 128, the deterioration of the performance of the fuel cell stack 100 due to the vertical displacement difference between the frames 130 and 140 and the single cell 110 can be suppressed. Of all the first separators 120 provided in the fuel cell stack 100, it is preferable that 50% or more of the first separators 120 include the first connecting portion 128, and all the first separators 120. Of these, a configuration in which 80% or more of the first separator 120 includes the first connecting portion 128 is more preferable. Further, in particular, in the power generation unit 102 arranged at a position away from the end plates 104 and 106 in the vertical direction, a displacement difference between the frames 130 and 140 and the single cell 110 in the vertical direction is likely to occur. Therefore, the first separator 120 (the first separator 120 located on the central side in the vertical direction in the fuel cell stack 100) arranged at a position away from the end plates 104 and 106 in the vertical direction is the first connecting portion. A configuration including 128 is preferred.

Further, in the above embodiment, all the cross sections passing through the center O of the single cell 110 in the vertical direction (Z-axis direction) and parallel to the vertical direction satisfy the first to sixth requirements. However, the present invention is not limited to this, and the first to sixth requirements may be satisfied in at least one cross section that passes through the center O of the single cell 110 in the vertical direction) and is parallel to the vertical direction. Specifically, in the above embodiment, the first connecting portion 128 is formed over the entire circumference of the single cell 110 in the first separator 120 in the vertical direction, but the first connecting portion If 128 is formed in at least a part of the first separator 120 around the single cell 110, the fuel cell stack 100 of the fuel cell stack 100 due to the vertical displacement difference between the frames 130 and 140 and the single cell 110. It is possible to suppress the deterioration of performance. For example, in the above embodiment, the first connecting portion 128 may be formed so as to be located at at least one of the first to fourth partition regions E1 to E4. The first connecting portion 128 is preferably formed only in 50% or more of the entire circumference around the single cell 110 in the first separator 120, and is simply in the first separator 120. A configuration formed only in 80% or more of the entire circumference around the cell 110 is preferable. The same applies to the second connecting portion 188 of the second separator 180.

Further, in the above embodiment, the first connecting portion 128 has a curved shape so as to project toward the fuel chamber 176 side (lower side), but the first connecting portion 128 has an air chamber 166 side. It may have a curved shape so as to project (upper side). Further, in the above embodiment, the first connecting portions 128 formed on all the first separators 120 have a shape curved in the same direction (lower side), but are formed on some of the first separators 120. The formed first connecting portion 128 may have a shape curved in the direction opposite to that of the first connecting portion 128 formed on the other first separator 120 (upper side). However, as in the above embodiment, if the first connecting portions 128 formed on all the first separators 120 are curved in the same direction, the end plates 104 and 106 and the single cell 110 are in the vertical direction. Since all the first separators 120 are always uniformly deformed in the same direction with respect to the fluctuation of the displacement difference, it is possible to suppress a short circuit between the first separators 120. The depth of the recess of the first connecting portion 128 is preferably longer than the opening width of the recess (see FIG. 8). The same applies to the second connecting portion 188 of the second separator 180.

Further, in the above embodiment, the first separator 120 does not have to satisfy any of the above-mentioned first to third requirements, and has a configuration that satisfies at least one or two. You may. Further, the second separator 180 may be configured not to include the second connecting portion 188. Further, the second separator 180 may not satisfy any of the above-mentioned fourth to sixth requirements, and may have a configuration that satisfies at least one or two. Further, one of the first separator 120 and the second separator 180 may not have a connecting portion (first connecting portion 128, second connecting portion 188). For example, in the above embodiment, instead of the second separator 180, a flat plate-shaped separator may be used as a whole without providing an uneven portion such as the second connecting portion 188. The flat plate-shaped separator preferably has a thickness in the vertical direction thinner than the thickness in the vertical direction of the interconnector 150 and is more flexible (easily flexible) than the interconnector 150. According to such a configuration, the flat plate-shaped separator is more easily bent and deformed than the interconnector bonded to the flat plate-shaped separator. Therefore, when the displacement difference between the frame member and the single cell in the vertical direction becomes large, the flat plate-shaped separator is deformed so as to bend. As a result, the stress generated in the single cell or the frame member is relaxed by the displacement difference, so that the deterioration of the performance of the fuel cell stack 100 due to the vertical displacement difference between the frame member and the single cell can be suppressed. it can. The flat plate-shaped separator corresponds to the second separator in the claims.

Further, at least one of the first separator 120 and the second separator 180 has an inner portion (first inner portion 126, first inner portion 126, first) instead of the connecting portion (first connecting portion 128, second connecting portion 188). The configuration may include a flexible portion formed of a material that is more flexible than the inner portion 186) and the outer portion (first outer portion 127, second outer portion 187) of 2. In short, the fuel cell stack 100 includes a cell-side joint that is directly or indirectly joined to the single cell 110, and a frame-side joint that is joined to the frames 130 and 140, and the cell-side joint. Any configuration may include a flexible member having flexibility that deforms so that the relative position in the vertical direction between the joint and the frame side joint is displaced.

Further, in the above embodiment, the number of single cells 110 included in the fuel cell stack 100 is only an example, and the number of single cells 110 is appropriately determined according to the output voltage and the like required for the fuel cell stack 100. Further, the material constituting each member in the above embodiment is merely an example, and each member may be composed of another material.

Further, 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 comprises an electrolysis reaction of water. It is also applicable to an electrolytic single cell, which is a constituent unit of a solid oxide fuel cell (SOEC) that generates hydrogen by utilizing it, and an electrolytic cell stack including a plurality of electrolytic single cells. 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 generally the same as the fuel cell stack 100 in the above-described embodiment. It is the composition of. 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 single 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. Water vapor 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, by forming the first connecting portion 128 on the first separator 120, the displacement difference between the end plates 104 and 106 and the single cell 110 in the vertical direction can be reduced. It is possible to suppress the deterioration of the performance of the fuel cell stack 100 due to this.

Further, in the above embodiment, the solid oxide fuel cell (SOFC) has been described as an example, but the present invention can be applied to other types of fuel cells (or electrolytic single cells) such as a molten carbonate fuel cell (MCFC). Is also applicable.

22: Bolt 24: Nut 26: Insulation sheet 27: Gas passage member 28: Main body 29: Branch 100: Fuel cell stack 100a: Fuel cell stack 102: Power generation unit 103: Cell block 104, 106: End plate 104A, 106A : Opening window 108: Communication hole 110: Single cell 112: Electrolyte layer 114: Air pole 116: Fuel pole 120, 120a: First separator 121: First separator through hole 122: First through hole peripheral part 123: Cell side joint part 124: Joint part 126: First inner part 127: First outer part 128: First connection part 129: Frame side joint part 130: Air pole side frame 131: Air chamber hole 132: Oxidation Agent gas supply communication flow path 133: Oxidizing agent gas discharge communication flow path 134: Air electrode side current collector 135: Current collector element 140: Fuel pole side frame 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 161: Oxidizing agent gas introduction manifold 162: Oxidating agent gas discharging Manifold 166: Air chamber 171: Fuel gas introduction manifold 172: Fuel gas discharge manifold 176: Fuel chamber 180: Second separator 181: Second separator through hole 182: Second through hole peripheral part 183: Connector side joint 186: Second inner part 187: Second outer part 188: Second connecting part 189: Frame side joint 190: Intermediate member B1: Shortest distance Δ B2: Shortest distance Δ C1: Length Δ C2: Length Δ E1 to E4: Partition area FG: Fuel gas FOG: Fuel off gas OG: Oxidating agent gas OOG: Oxidizing agent off gas 70: Upper terminal plate 78: Projection 80: Lower terminal plate 88: Projection 92: Upper insulating sheet 94 : Lower insulating sheet 100b: Fuel cell stack 100c: Fuel cell stack 102X: Upper specific power generation unit 150X: Top level interconnector 180X: Top level separator 181X: Top level separator through hole 182X: Third penetration Peripheral part of through hole 186X: Third inner part 187X: Third outer part 188X: Third connecting part 211: Welded part 212: Welded part 231: Welded part 232: Welded part 241: Welded part

Claims (9)

A single cell containing an electrolyte layer and an air electrode and a fuel electrode facing each other in the first direction across the electrolyte layer, and an air electrode side frame through hole forming an air chamber facing the air electrode were formed. An electrochemical reaction block in which a plurality of electrochemical reaction units including an air electrode side frame member are arranged side by side in the first direction,
A pair of end members located on both sides of the electrochemical reaction block in the first direction and arranged so that at least a part thereof overlaps the frame member on the air electrode side in the first direction.
In an electrochemical reaction cell stack comprising
At least one of the pair of end members is formed with a space that opens at least toward the electrochemical reaction block side and whose contour line includes the single cell in the first directional view.
Further, the cell side joint portion directly or indirectly joined to the single cell and the air pole side frame side joint portion joined to the air pole side frame member are provided, and the cell side joint portion is provided. A first flexible member having flexibility that deforms so that the relative position between the air pole side and the frame side joint portion in the first direction is displaced.
It is characterized by an electrochemical reaction cell stack. In the electrochemical reaction cell stack according to claim 1,
The first flexible member connects an inner portion including the cell-side joint portion, an outer portion located on the outer peripheral side of the inner portion, and the inner portion and the outer portion, and the inner portion thereof. A connecting portion that projects to one side in the first direction is provided for both the portion and the outer portion.
It is characterized by an electrochemical reaction cell stack. In the electrochemical reaction cell stack according to claim 2.
In at least one cross section parallel to the first direction, a third direction orthogonal to the first direction between the cell-side joint and the air-pole-side frame-side joint in the first flexible member. The first distance, which is the distance in the direction, is the second distance in the first direction between the cell-side joint portion and the air electrode-side frame-side joint portion of the first flexible member. Longer than the distance
It is characterized by an electrochemical reaction cell stack. In the electrochemical reaction cell stack according to claim 2 or 3.
In at least one cross section parallel to the first direction, the length of the connecting portion in the first flexible member is the cell-side joint and the air in the first flexible member. From the shortest distance to the pole-side frame-side joint, subtract the first distance, which is the distance between the cell-side joint and the air-pole-side frame-side joint in the third direction orthogonal to the first direction. Longer than the length
It is characterized by an electrochemical reaction cell stack. In the electrochemical reaction cell stack according to any one of claims 1 to 4.
In the electrochemical reaction block, a first separator through hole is further formed in each of the electrochemical reaction units, and a portion around the first through hole surrounding the first separator through hole is joined to the single cell. A plurality of first separators are provided, wherein the first peripheral edge portion is joined to the air electrode side frame member, and the air chamber and the fuel chamber facing the fuel electrode are separated.
At least one said first separator is said said first flexible member.
It is characterized by an electrochemical reaction cell stack. In the electrochemical reaction cell stack according to any one of claims 1 to 5.
The electrochemical reaction block further
A plurality of interconnectors arranged in the first direction of each single cell, and
A fuel pole side frame member having a fuel pole side frame through hole forming a fuel chamber facing the fuel pole, and a fuel pole side frame member.
A second separator through hole is formed, a portion around the second through hole surrounding the second separator through hole is joined to the interconnector, and a second peripheral edge portion is joined to the fuel electrode side frame member. A plurality of second separators that separate the fuel chamber and the adjacent air chamber of the single cell.
The at least one second separator includes a connector-side joint that is directly or indirectly joined to the interconnector and a fuel-pole-side frame-side joint that is joined to the fuel-pole-side frame member. Moreover, it is a second flexible member having flexibility that deforms so that the relative position of the connector side joint portion and the fuel pole side frame side joint portion in the first direction is displaced.
It is characterized by an electrochemical reaction cell stack. In the electrochemical reaction cell stack according to claim 6,
The second separator is a member whose thickness in the first direction is thinner than the thickness in the first direction of the interconnector and which is more flexible than the interconnector.
It is characterized by an electrochemical reaction cell stack. In the electrochemical reaction cell stack according to claim 6 or 7.
The at least one second separator is welded to the interconnector and the fuel electrode side frame member, respectively.
It is characterized by an electrochemical reaction cell stack. In the electrochemical reaction cell stack according to any one of claims 1 to 8.
The space is formed in the first end member, which is one of the pair of end members.
The electrochemical reaction cell stack further
A terminal member located between the electrochemical reaction block and the first end member in the first direction and at least partially overlapped with the air electrode side frame member. A conductive terminal member having a terminal member through hole that penetrates in the first direction and communicates with the space formed in the first end member.
An insulating member located between the first end member and the terminal member in the first direction and arranged so that at least a part thereof overlaps the air electrode side frame member. An insulating insulating member having an insulating member through hole formed in the first end member and communicating with the space.
Among the plurality of interconnectors arranged in the first direction of each single cell, the specific interconnector having the shortest distance to the terminal member in the first direction and
A third separator through hole is formed, a third through hole peripheral portion surrounding the third separator through hole is joined to the specific interconnector, and a third peripheral edge portion is joined to the terminal member. With a conductive third separator,
The third separator is joined to the terminal member and the specific interconnector by welding, respectively.
It is characterized by an electrochemical reaction cell stack.

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