JP2005276484A - Fuel cell stack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable to maintain power generation performance and sealing performance by certainly applying a desired tightening load with a simple and compact structure. <P>SOLUTION: The casing 24 comprises end plates 20a, 20b and side plates 60a-60d. A coupling pin 64a is inserted in the tab portions 66a, 66b of the end plates 20a, 20b and the tab portions 70a, 70b of the side plates 60a, 60c, and a coupling pin 64b is inserted in the tab portions 66a, 66b of the end plate 20a and the tab portions 72a, 72b of the above side plates 60b, 60d. At this time, a plurality of coupling pins 64a, 64b selected respectively in various different diameters are prepared and by using any coupling pins 64a, 64b, the distance between the end plates 20a, 20b can be adjusted. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention includes a unit cell in which an electrolyte / electrode structure in which a pair of electrodes are provided on both sides of an electrolyte is sandwiched between separators, and a stacked body in which a plurality of the unit cells are stacked is contained in a box-shaped casing. It relates to a battery stack.

  For example, a polymer electrolyte fuel cell employs an electrolyte membrane (electrolyte) made of a polymer ion exchange membrane. A fuel cell is configured by sandwiching an electrolyte membrane / electrode structure in which an anode side electrode and a cathode side electrode are provided on both sides of the electrolyte membrane with a separator. Each of the anode side electrode and the cathode side electrode has a noble metal-based electrode catalyst layer bonded to a base material mainly composed of carbon.

  In this fuel cell, a fuel gas, for example, a gas mainly containing hydrogen (hereinafter also referred to as hydrogen-containing gas) is supplied to the anode side electrode, while an oxidant gas, for example, A gas or air mainly containing oxygen (hereinafter also referred to as oxygen-containing gas) is supplied. In the fuel gas supplied to the anode side electrode, hydrogen is ionized on the electrode catalyst and moves to the cathode side electrode side through the electrolyte membrane. Electrons generated during that time are taken out to an external circuit and used as direct current electric energy.

  Normally, this fuel cell is used as a fuel cell stack in which a predetermined number (for example, several tens to several hundreds) is stacked in order to obtain a desired power generation. In this fuel cell stack, the stacked fuel cells need to be reliably pressurized and held in order to prevent an increase in the internal resistance of the fuel cell and a decrease in the sealing performance of the reaction gas.

  Therefore, for example, a fuel cell stack of Patent Document 1 is known. As shown in FIG. 9, the fuel cell stack includes a stacked body 2 in which a plurality of unit cells 1 are stacked, and an auxiliary plate 4 a with end plates 3 and 3 interposed at both ends in the stacking direction of the stacked body 2. 4b are arranged.

  A pair of fastening bands 5 and 5 are disposed along both side portions of the laminate 2. Cylindrical connecting portions 6 are provided at the ends of the fastening bands 5 and 5 and the auxiliary plates 4a and 4b so that the respective holes are aligned in a straight line. The fastening bands 5 and 5 and the auxiliary plates 4a and 4b are integrally connected by inserting the metal pin 7 into each connecting portion 6.

  A plurality of bolts 8 are screwed onto the auxiliary plate 4a, while a plurality of disc springs 9 are disposed on the auxiliary plate 4b. Therefore, when the bolt 8 is screwed, the auxiliary plate 4a is pressed downward, and the disc spring 9 disposed on the auxiliary plate 4b is compressed, and the fastening pressure required for the laminate 2 via the end plate 3 is compressed. Is granted.

JP 2001-135344 A (FIG. 5)

  In said patent document 1, the metal pin 7 is integrally fitted by each connection part 6 of the fastening bands 5 and 5 and the connection part 6 of auxiliary plate 4a, 4b, Between the said auxiliary plates 4a, 4b. The distance is fixed. For this reason, when the tightening load of the fuel cell stack is reduced due to a change over time or the like, it is necessary to maintain a desired tightening load by tightening the plurality of bolts 8.

  However, in patent document 1, in order to adjust the fastening load of the fuel cell stack, a plurality of bolts 8 that are dedicated parts are provided. Accordingly, there is a problem that the weight of the fuel cell stack increases due to the addition of the dedicated parts, and the fuel cell stack is enlarged in the stacking direction of the unit cells 1.

  The present invention solves this type of problem, and with a simple and compact configuration, a desired tightening load can be reliably applied in the stacking direction of the stack, and the power generation performance and sealing performance of each unit cell can be improved. An object of the present invention is to provide a fuel cell stack that can be maintained.

  The present invention includes a unit cell in which an electrolyte / electrode structure in which a pair of electrodes are provided on both sides of an electrolyte is sandwiched between separators, and a stacked body in which a plurality of the unit cells are stacked is contained in a box-shaped casing. It is a battery stack.

  The casing includes end plates disposed at both end portions in the stacking direction of the laminate, a plurality of side plates disposed at the side portions of the laminate, a first connecting portion provided on the side plate, and a second provided on the side plate. A plurality of connecting pins, which are coaxially inserted into the connecting portion to connect the end plate and the side plate, are selected to have different diameters and can adjust the distance between the end plates.

  In the present invention, the casing includes end plates disposed at both ends in the stacking direction of the laminate, a plurality of side plates disposed at the side portions of the laminate, and the first connecting portion provided on the side plate or the Inserted in the second connecting part provided on the side plate, connects the end plate and the side plate with a connecting pin, and the connecting pin insertion hole is selected at a different position in the stacking direction to adjust the distance between the end plates A plurality of connecting piece members.

  Furthermore, it is preferable that the separator is composed of a metal plate having a concavo-convex shape corresponding to the reaction gas flow path. Therefore, it is not necessary to provide a member that absorbs expansion and contraction such as a disc spring at the end of the laminated body.

  In the present invention, when the diameter of the connecting pin is changed, the end plate is positioned in the stacking direction of the unit cells with respect to the side plate due to a dimensional difference between the inner diameter of the first and second connecting portions and the outer diameter of the connecting pin. It is adjusted and the distance between the end plates is changed. For example, when a connecting pin with a small diameter is used, the distance between the end plates increases, while when a connecting pin with a large diameter is used, the distance between the end plates decreases.

  Therefore, if a fuel cell stack is assembled using connecting pins with a small diameter in advance, when the tightening load decreases due to changes over time, the connecting pin with a large diameter is simply assembled instead of the connecting pin with a small diameter. The distance between the end plates is shortened and the tightening load is increased. In addition, when the fuel cell stack is assembled, the tightening adjustment of the tightening bolts is not necessary, and the assembly operation of the fuel cell stack can be easily performed.

  Thereby, it is possible to reliably apply a desired tightening load in the stacking direction of the stacked body with a simple and compact configuration, and to maintain the power generation performance and sealing performance of each unit cell.

  In the present invention, when the position of the connecting pin insertion hole is changed in the stacking direction, the end plates are adjusted in the stacking direction of the unit cells with respect to the side plates, and the distance between the end plates is changed. For this reason, it is possible to reliably apply a desired tightening load in the stacking direction of the stacked body with a simple and compact configuration, and to maintain the power generation performance and sealing performance of each unit cell.

  FIG. 1 is a partially exploded schematic perspective view of a fuel cell stack 10 according to the first embodiment of the present invention, and FIG. 2 is a partial sectional side view of the fuel cell stack 10.

  As shown in FIG. 1, the fuel cell stack 10 includes a stacked body 14 in which a plurality of unit cells 12 are stacked in the horizontal direction (arrow A direction). A terminal plate 16a, an insulating plate 18 and an end plate 20a are sequentially disposed at one end in the stacking direction (arrow A direction) of the stacked body 14 toward the outside. At the other end in the stacking direction of the stacked body 14, a terminal plate 16b, an insulating spacer member 22 and an end plate 20b are sequentially disposed outward.

  The fuel cell stack 10 is integrally held by a box-shaped casing 24 including end plates 20a and 20b each having a substantially rectangular shape as end plates. The end plates 20a and 20b only need to be configured in a polygonal shape, and can be set to various shapes such as a substantially hexagonal shape and a substantially octagonal shape.

  As shown in FIGS. 2 and 3, each unit cell 12 includes an electrolyte membrane / electrode structure (electrolyte / electrode structure) 30, and a thin plate-shaped first and second sandwiching the electrolyte membrane / electrode structure 30. Second metal separators 32 and 34 are provided.

  One end edge of the unit cell 12 in the horizontal direction (in the direction of arrow B in FIG. 3) communicates with each other in the direction of arrow A, and an oxidant gas supply communication for supplying an oxidant gas, for example, an oxygen-containing gas. A hole 36a, a cooling medium supply communication hole 38a for supplying a cooling medium, and a fuel gas discharge communication hole 40b for discharging a fuel gas, for example, a hydrogen-containing gas, are provided.

  At the other end edge of the unit cell 12 in the horizontal direction, a fuel gas supply communication hole 40a for supplying fuel gas and a cooling medium discharge communication hole 38b for discharging the cooling medium communicate with each other in the direction of arrow A. , And an oxidant gas discharge passage 36b for discharging the oxidant gas.

  The electrolyte membrane / electrode structure 30 includes, for example, a solid polymer electrolyte membrane 42 in which a perfluorosulfonic acid thin film is impregnated with water, and an anode side electrode 44 and a cathode side electrode 46 that sandwich the solid polymer electrolyte membrane 42. With.

  The anode side electrode 44 and the cathode side electrode 46 are composed of a gas diffusion layer made of carbon paper or the like, and an electrode catalyst layer in which porous carbon particles carrying a platinum alloy on the surface are uniformly applied to the surface of the gas diffusion layer. And have. The electrode catalyst layer is bonded to both surfaces of the solid polymer electrolyte membrane 42.

  A fuel gas flow path 48 that connects the fuel gas supply communication hole 40 a and the fuel gas discharge communication hole 40 b is formed on the surface 32 a of the first metal separator 32 facing the electrolyte membrane / electrode structure 30. The fuel gas channel 48 is constituted by, for example, a plurality of grooves extending in the arrow B direction. On the surface 32b of the first metal separator 32, a cooling medium flow path 50 that connects the cooling medium supply communication hole 38a and the cooling medium discharge communication hole 38b is formed. The cooling medium flow path 50 is configured by a plurality of grooves extending in the arrow B direction.

  The surface 34a of the second metal separator 34 facing the electrolyte membrane / electrode structure 30 is provided with, for example, an oxidant gas flow path 52 composed of a plurality of grooves extending in the direction of arrow B, and this oxidant gas. The flow path 52 communicates with the oxidant gas supply communication hole 36a and the oxidant gas discharge communication hole 36b. A cooling medium flow path 50 is integrally formed on the surface 34 b of the second metal separator 34 so as to overlap the surface 32 b of the first metal separator 32.

  A first seal member 54 is integrally formed on the surfaces 32 a and 32 b of the first metal separator 32 around the outer peripheral end of the first metal separator 32. The first seal member 54 surrounds the fuel gas supply communication hole 40a, the fuel gas discharge communication hole 40b, and the fuel gas flow path 48 on the surface 32a so as to communicate with each other, and on the surface 32b, the cooling medium supply communication hole 38a, The medium discharge communication hole 38b and the cooling medium flow path 50 are surrounded and communicated with each other.

  A second seal member 56 is integrally formed on the surfaces 34 a and 34 b of the second metal separator 34 around the outer peripheral end of the second metal separator 34. The second seal member 56 surrounds and communicates the oxidant gas supply communication hole 36a, the oxidant gas discharge communication hole 36b, and the oxidant gas flow path 52 on the surface 34a, while the cooling medium supply communication hole on the surface 34b. 38a, the cooling medium discharge communication hole 38b, and the cooling medium flow path 50 are surrounded and communicated.

  As shown in FIG. 2, a seal 57 is interposed between the first and second seal members 54 and 56 to prevent the outer periphery of the solid polymer electrolyte membrane 42 from directly contacting the casing 24. The outer peripheral end portions of the first and second seal members 54 and 56 may have a slight gap with the inner surface of the casing 24, or may be in contact with the inner surface.

  As shown in FIGS. 1 and 2, plate-like terminal portions 58a and 58b protruding in the surface direction are formed at the ends of the terminal plates 16a and 16b. For example, a load such as a traveling motor is connected to the terminal portions 58a and 58b.

  As shown in FIG. 1, the casing 24 includes end plates 20 a and 20 b that are end plates, a plurality of side plates 60 a to 60 d disposed on the side of the laminated body 14, and end portions of the side plates 60 a to 60 d that are close to each other. Angle members (for example, L angles) 62a to 62d that connect the portions, and connecting pins 64a and 64b having different lengths that connect the end plates 20a and 20b and the side plates 60a to 60d, respectively. The connection pins 64a and 64b include a plurality of connection pins 64a and 64b set to various different diameters D1 to Dn as described later.

  The angle members 62a to 62d are interposed between the laminated body 14 and the side plates 60a to 60d, and are disposed at the four corners (corner portions) of the laminated body 14. The side plates 60a to 60d are configured to be relatively thin, while the angle members 62a to 62d are configured to be thicker than the side plates 60a to 60d.

  Two tab portions 66a and 66b project from the upper and lower sides of the end plates 20a and 20b, respectively, and one tab portion 66a and 66b project from the sides on both sides. Hole portions 67a and 67b are formed in the tab portions 66a and 66b. Mount bosses 68a and 68b are formed at the lower ends of the respective sides of the end plates 20a and 20b. The boss portions 68a and 68b are fixed to a mounting portion (not shown) via a bolt or the like, so that the fuel cell stack 10 is mounted on, for example, a vehicle.

  Two tab portions 70a and 70b are formed at both ends in the longitudinal direction of the side plates 60a and 60c arranged on both sides of the laminated body 14, respectively. Hole portions 71a and 71b are formed in the tab portions 70a and 70b. Three tab portions 72a and 72b are formed at both ends in the longitudinal direction of the side plates 60b and 60d arranged above and below the laminated body 14, respectively. Hole portions 73a and 73b are formed in the tab portions 72a and 72b.

  Between the tab portions 70a and 70b of the side plates 60a and 60c, tab portions 66a and 66b on both sides of the end plates 20a and 20b are disposed, and a short connecting pin 64a is integrally inserted therein. The side plates 60a and 60c are attached to the end plates 20a and 20b.

  Similarly, the tab portions 72a and 72b of the side plates 60b and 60d are alternately arranged with the tab portions 66a and 66b on the upper side and the lower side of the end plates 20a and 20b, and a long connecting pin 64b is inserted integrally therewith. Then, the side plates 60b and 60d are attached to the end plates 20a and 20b.

  In the side plates 60a to 60d, a plurality of hole portions 74 are formed at both edges in the short direction, and screw holes 76 are formed on the sides of the angle members 62a to 62d corresponding to the hole portions 74. Is done. The screws 78 inserted into the holes 74 are screwed into the screw holes 76, whereby the side plates 60a to 60d are fixed to the angle members 62a to 62d. Thereby, the casing 24 is configured (see FIG. 4).

  As shown in FIGS. 1 and 2, the spacer member 22 has a rectangular shape set to a predetermined size so as to be positioned on the inner periphery of the casing 24. The spacer member 22 is adjusted in thickness in order to absorb a variation in the length of the stacked body 14 in the stacking direction and to apply a desired tightening load to the stacked body 14, and is used as necessary. It has been.

  The operation of assembling the fuel cell stack 10 configured as described above will be described below.

  First, connecting pins 64a and 64b each having a relatively small diameter D1 are selected. As shown in FIG. 5, the connecting pins 64a are connected to the tab portions 66a and 66b of the end plates 20a and 20b, The tabs 70a and 70b of the side plates 60a and 60c are inserted integrally. At that time, the diameter D1 of the connecting pin 64a is set to be considerably smaller than the respective opening diameters of the holes 67a and 67b of the tab portions 66a and 66b and the holes 71a and 71b of the tab portions 70a and 70b. For this reason, the end plates 20a and 20b can be separated from each other by a relatively large distance L1.

  On the other hand, the connecting pin 64b is similarly set to a relatively small diameter D1. Thus, the end plates 20a and 20b can hold a relatively large distance L1 with the side plates 60b and 60d attached to the end plates 20a and 20b.

  Next, the operation of the fuel cell stack 10 will be described below.

  In the fuel cell stack 10, first, as shown in FIG. 4, an oxidant gas such as an oxygen-containing gas is supplied to the oxidant gas supply communication hole 36a of the end plate 20a, and hydrogen is supplied to the fuel gas supply communication hole 40a. Fuel gas such as contained gas is supplied. Further, a coolant such as pure water or ethylene glycol is supplied to the coolant supply passage 38a. For this reason, in the stacked body 14, the oxidant gas, the fuel gas, and the cooling medium are supplied in the direction of arrow A to the plurality of unit cells 12 stacked in the direction of arrow A.

  As shown in FIG. 3, the oxidant gas is introduced into the oxidant gas flow path 52 of the second metal separator 34 through the oxidant gas supply communication hole 36 a, and along the cathode side electrode 46 of the electrolyte membrane / electrode structure 30. Move. On the other hand, the fuel gas is introduced into the fuel gas passage 48 of the first metal separator 32 through the fuel gas supply communication hole 40 a and moves along the anode side electrode 44 of the electrolyte membrane / electrode structure 30.

  Therefore, in each electrolyte membrane / electrode structure 30, the oxidant gas supplied to the cathode side electrode 46 and the fuel gas supplied to the anode side electrode 44 are consumed by an electrochemical reaction in the electrode catalyst layer, Power generation is performed.

  Next, the oxidant gas consumed by being supplied to the cathode side electrode 46 flows along the oxidant gas discharge communication hole 36b, and then is discharged to the outside from the end plate 20a. Similarly, the fuel gas consumed by being supplied to the anode side electrode 44 is discharged to the fuel gas discharge communication hole 40b, flows, and is discharged from the end plate 20a to the outside.

  The cooling medium flows in the direction of arrow B after being introduced into the cooling medium flow path 50 between the first and second metal separators 32 and 34 from the cooling medium supply communication hole 38a. The cooling medium cools the electrolyte membrane / electrode structure 30, and then moves through the cooling medium discharge communication hole 38b and is discharged from the end plate 20a.

  Incidentally, in the fuel cell stack 10 described above, the tightening load of the stacked body 14 may decrease with time due to, for example, the sag of the first and second metal separators 32 and 34. Therefore, in the first embodiment, the connecting pins 64a and 64b set to the relatively large diameter D2 are incorporated into the casing 24 instead of the connecting pins 64a and 64b set to the relatively small diameter D1. Is done.

  At that time, as shown in FIG. 6, the connecting pin 64a set to the diameter D2 has substantially the same dimensions as the opening diameters of the holes 67a, 67b, 71a and 71b of the tabs 66a, 66b, 70a and 70b. Is set to Accordingly, when the connecting pin 64a is integrally inserted between the holes 67a and 71a, 67a and 71b, 67b and 71a, and 67b and 71b, the distance L2 between the end plates 20a and 20b is adjusted to be shorter than the distance L1. The

  As a result, the tightening load applied to the laminate 14 increases, and even if the tightening load decreases due to changes over time such as sag, the desired tightening load is reliably applied to the laminate 14. Can be obtained.

  On the other hand, the connecting pin 64b set to a relatively large diameter D2 is substantially fitted in the holes 67a, 67b, 73a and 73b of the tab portions 66a, 66b, 72a and 72b, similarly to the connecting pin 64a. To be inserted. For this reason, the distance between the end plates 20a and 20b is effectively shortened (distance L2), and the tightening load of the laminate 14 can be increased.

  As described above, in the first embodiment, a plurality of connecting pins 64a and 64b set to different diameters D1 and D2 or different diameters D3 to Dn are prepared and selected according to changes in the tightening load. The fastening load between the end plates 20a and 20b can be changed simply by assembling the connecting pins 64a and 64b to the casing 24.

  Therefore, for example, it is not necessary to adjust the tightening load by adjusting the tightening of the tightening bolt, and the assembly work of the fuel cell stack 10 can be easily simplified.

  Thereby, in the first embodiment, a desired tightening load can be reliably applied in the stacking direction of the stacked body 14 with a simple and compact configuration, and the power generation performance and the sealing performance of each unit cell 12 can be maintained. There is an advantage that a high-quality fuel cell stack 10 can be obtained.

  FIG. 7 is a partial cross-sectional explanatory view of a box-shaped casing 82 that houses a fuel cell stack 80 according to the second embodiment of the present invention. The same components as those of the fuel cell stack 10 and the casing 24 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  The side plates 60a to 60 constituting the casing 82 have tab portions 84 formed at both ends in the longitudinal direction. The tab portion 84 is provided with an opening 86 having a rectangular opening cross section that is long in the stacking direction. In the opening 86, the connecting pin insertion holes 88a and 88b are selected at different positions in the stacking direction, and the end plate 20a, Two types of connecting piece members 90a and 90b capable of adjusting the distance between 20b are selectively accommodated (see FIGS. 7 and 8).

  In the second embodiment configured as described above, first, the connecting piece member 90a is accommodated in the opening 86 of each tab portion 84, and the connecting pin 92 is connected to the connecting pin insertion hole of the connecting piece member 90a. 88a and tab portions 66a and 66b are integrally inserted. At that time, the connecting piece member 90a has the connecting pin insertion hole 88a decentered outward in the stacking direction from the center position, and the end plates 20a and 20b can be separated from each other by a relatively large distance L1 (FIG. 7). reference).

  On the other hand, when the tightening load of the laminated body 14 is lowered, as shown in FIG. 8, a connecting piece member 90b is used instead of the connecting piece member 90a. Here, in the connecting piece member 90b, the connecting pin insertion hole 88b is set at a substantially central position. Therefore, when the connecting pin 92 is integrally inserted into the connecting pin insertion hole 88b and the tab portions 66a and 66b of the connecting piece member 90b, the distance L2 between the end plates 20a and 20b is adjusted to be shorter than the distance L1.

  As a result, the tightening load applied to the laminate 14 increases, and even if the tightening load decreases due to changes over time such as sag, the desired tightening load is reliably applied to the laminate 14. The same effect as the first embodiment can be obtained.

1 is a partially exploded schematic perspective view of a fuel cell stack according to an embodiment of the present invention. It is a partial cross section side view of the said fuel cell stack. It is a disassembled perspective explanatory drawing of the unit cell which comprises the said fuel cell stack. It is a perspective view of the fuel cell stack. It is explanatory drawing at the time of incorporating a small diameter connection pin in the casing which comprises the said fuel cell stack. It is explanatory drawing at the time of incorporating a large diameter connecting pin in the casing. It is a partial cross section explanatory view of the box-shaped casing which stored the fuel cell stack concerning a 2nd embodiment of the present invention. It is a partial cross section explanatory view of the casing in which a different connection piece member was used. 1 is a schematic explanatory diagram of a fuel cell of Patent Document 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 80 ... Fuel cell stack 12 ... Unit cell 14 ... Laminated body 16a, 16b ... Terminal plate 18 ... Insulating plate 20a, 20b ... End plate 22 ... Spacer member 24 ... Casing 30 ... Electrolyte membrane and electrode structure 32, 34 ... Metal separator 42 ... Solid polymer electrolyte membrane 44 ... Anode side electrode 46 ... Cathode side electrode 48 ... Fuel gas channel 50 ... Coolant flow channel 52 ... Oxidant gas channel 54, 56 ... Seal members 60a-60d ... Side plate 62a ... 62d ... Angle members 64a, 64b, 92 ... Connecting pins 66a, 66b, 70a, 70b, 72a, 72b, 84 ... Tab portions 67a, 67b, 71a, 71b, 73a, 73b, 74 ... Holes 78 ... Screws 88a, 88b ... Connecting pin insertion holes 90a, 90b ... Connecting piece members

Claims (3)

A fuel cell stack comprising a unit cell in which an electrolyte / electrode structure having a pair of electrodes provided on both sides of an electrolyte is sandwiched between separators, and a stacked body in which a plurality of the unit cells are stacked is housed in a box-shaped casing. And
The casing includes end plates disposed at both ends in the stacking direction of the stacked body,
A plurality of side plates disposed on the side of the laminate;
The end plate and the side plate are coaxially inserted into the first connecting portion provided on the side plate and the second connecting portion provided on the side plate, and are selected to have different diameters. A plurality of adjustable connecting pins,
A fuel cell stack comprising: A fuel cell stack comprising a unit cell in which an electrolyte / electrode structure having a pair of electrodes provided on both sides of an electrolyte is sandwiched between separators, and a stacked body in which a plurality of the unit cells are stacked is housed in a box-shaped casing. And
The casing includes end plates disposed at both ends in the stacking direction of the stacked body,
A plurality of side plates disposed on the side of the laminate;
Inserted into the first connecting part provided on the side plate or the second connecting part provided on the side plate, the end plate and the side plate are connected by a connecting pin, and the connecting pin insertion holes are selected at different positions in the stacking direction. A plurality of connecting pieces that can adjust the distance between the end plates;
A fuel cell stack comprising: 3. The fuel cell stack according to claim 1, wherein the separator is formed of a metal plate having a concavo-convex shape corresponding to the reaction gas flow path. 4.

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