JP4362286B2 - Fuel cell stack - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel cell stack in which a plurality of electrolyte / electrode structures each provided with electrodes on both sides of an electrolyte are stacked via a separator.
[0002]
[Prior art]
In recent years, various fuel cells have been developed. For example, solid polymer fuel cells are known. This polymer electrolyte fuel cell employs an electrolyte membrane (electrolyte) made of a polymer ion exchange membrane (cation exchange membrane). An electrolyte membrane / electrode structure (electrolyte / electrode structure) in which an anode catalyst and a cathode electrode made of an electrode catalyst and porous carbon are provided on both sides of the electrolyte membrane is sandwiched between separators (bipolar plates). Thus, a unit cell is configured.
[0003]
In this type of fuel cell (unit cell), a fuel gas supplied to the anode side electrode, for example, a gas mainly containing hydrogen (hereinafter also referred to as a hydrogen-containing gas) is hydrogen ionized on the electrode catalyst, It moves to the cathode side electrode side through the electrolyte. Electrons generated during that time are taken out to an external circuit and used as direct current electric energy. The cathode side electrode is supplied with an oxidant gas, for example, a gas mainly containing oxygen or air (hereinafter also referred to as an oxygen-containing gas). And oxygen react to produce water.
[0004]
Normally, this fuel cell is used as a fuel cell stack in which a predetermined number is stacked in order to obtain a desired power generation. This fuel cell stack is housed in a case, for example, and 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, the stacked fuel cells are pressurized with each other. Is held under pressure.
[0005]
As the fuel cell stack, for example, a fuel cell disclosed in Patent Document 1 is known. In Patent Document 1, a stack 2 is accommodated in a case 1 as shown in FIG. A fuel supply / discharge section 3 is disposed at one end of the stack 2, and a pressure plate 4 is disposed at the other end of the stack 2. The pressure plate 4 is provided with a plate guide 5, and this plate guide 5 is engaged with a rail portion 6 provided on the inner wall surface of the case 1 so as to extend in the stacking direction. The pressure plate 4 is pressurized toward the fuel supply / discharge section 3 via the pressurizing mechanism 7.
[0006]
In such a configuration, when the pressure plate 4 is pressurized via the pressurizing mechanism 7, the plate guide 5 provided on the pressure plate 4 and the rail portion 6 provided on the inner wall surface of the case 1. Under the guiding action, the pressure plate 4 does not tilt, and the stack 2 can be reliably pressurized.
[0007]
[Patent Document 1]
JP-A-10-189025 (paragraphs [0092], [0093], FIG. 16)
[0008]
[Problems to be solved by the invention]
However, when pressure is applied to the stack 2 from the end of the stack 2 through the pressure plate 4 under the action of the pressurizing mechanism 7, the parallelism is maintained for each unit cell constituting the stack 2. It is difficult.
[0009]
For example, when the separator constituting each unit cell is constituted by a thin plate-like metal separator, it is extremely difficult to obtain the parallelism of the separator. Therefore, in the stack 2 in which a plurality of unit cells are stacked, the surface pressure acting on at least some of the unit cells cannot be maintained uniformly. Thereby, the contact resistance in the stack 2 is increased, and a problem that a desired sealing property cannot be ensured for the separator is pointed out.
[0010]
The present invention solves this kind of problem, and aims to provide a fuel cell stack capable of maintaining the surface pressure of each unit cell to be laminated uniformly and simplifying the configuration. To do.
[0011]
[Means for Solving the Problems]
The fuel cell stack according to claim 1 of the present invention includes a unit cell in which an electrolyte / electrode structure provided with electrodes on both sides of an electrolyte is sandwiched by separators, and a plurality of the unit cells are stacked to form a stack. In addition, the laminate is accommodated in the case member.
[0012]
A pair of end plates that are integrally fixed to the case member are disposed at both ends in the stacking direction of the stacked body, while a predetermined position in the stacking direction, that is, a predetermined number of unit cells is provided in the stacked body. together with the intermediate plate are arranged corresponding to the intermediate plate is supported to maintain the parallelism to movably and the stacking direction in the stacking direction of the unit cell with respect to the case member via the supporting mechanism Has been.
[0013]
As described above, since the laminated body is divided into a predetermined number of unit cells via the intermediate plate, there is no possibility that the shape error of each unit cell is accumulated and the laminated body is inclined in the laminating direction. Moreover, the intermediate plate can advance and retreat while maintaining parallelism in the stacking direction under the action of the support mechanism. Therefore, the intermediate plate can follow the expansion and contraction due to the swelling and thermal stress of the laminated body, and can reliably prevent the laminated body from being inclined in the lamination direction. As a result, it becomes possible to improve the straightness of the laminate and stabilize the dimensions of the entire laminate. Furthermore, the surface pressure in the laminated body can be maintained uniformly, and the contact resistance in the laminated body can be reduced with a simple configuration, and a desired sealing property can be secured to easily improve the power generation performance. .
[0014]
In the fuel cell stack according to claim 2 of the present invention, the support mechanism includes a guide member that is fixed to the intermediate plate, and a guide groove that is provided on the case member and guides the guide member in the stacking direction. Yes. For this reason, the structure of the support mechanism is effectively simplified, and the support structure can be configured in a small size and economically.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a schematic overall perspective view of a fuel cell stack 10 according to a first embodiment of the present invention, and FIG. 2 is a partial sectional side view of the fuel cell stack 10.
[0016]
The fuel cell stack 10 includes a stacked body 14 in which a plurality of unit cells 12 are stacked in the direction of arrow A, and terminal terminal plates 16a and 16b and insulators are provided at both ends of the stacked body 14 in the stacking direction (arrow A direction). The plates 18a and 18b and the end plates 20a and 20b are sequentially arranged outward. Column-shaped terminal portions 22a and 22b are formed in the center portion of the terminal terminal plates 16a and 16b so as to protrude in the stacking direction, and the terminal portions 22a and 22b extend from the center portion of the insulator plates 18a and 18b in the stacking direction. Inserted into the protruding cylindrical portions 24a, 24b.
[0017]
The end plates 20 a and 20 b are integrally coupled via the case member 26. In the stacked body 14, for example, two intermediate plates 28 are disposed corresponding to predetermined positions in the stacking direction. The intermediate plate 28 is supported with respect to the case member 26 via the support mechanism 30 so that the intermediate plate 28 can advance and retreat in the stacking direction (arrow A direction) of the unit cells 12 and maintain parallelism.
[0018]
As shown in FIG. 3, each unit cell 12 includes an electrolyte membrane / electrode structure (electrolyte / electrode structure) 34, and first and second separators 36 and 38 that sandwich the electrolyte membrane / electrode structure 34. Is provided. The first and second separators 36 and 38 are made of, for example, a metal plate material. Note that the first and second separators 36 and 38 may be made of a carbon material or the like.
[0019]
One end edge in the long side direction (arrow B direction) of the electrolyte membrane / electrode structure 34 and the first and second separators 36 and 38 communicates with each other in the arrow A direction, and contains an oxidant gas, for example, oxygen An oxidant gas supply communication hole 40a for supplying gas, a cooling medium supply communication hole 42a for supplying a cooling medium, and a fuel gas discharge communication hole 44b for discharging a fuel gas, for example, a hydrogen-containing gas, are provided. It is done.
[0020]
Fuel gas supply communication holes for supplying fuel gas to the other end edges in the long side direction of the electrolyte membrane / electrode structure 34 and the first and second separators 36, 38 in communication with each other in the direction of arrow A 44a, a cooling medium discharge communication hole 42b for discharging the cooling medium, and an oxidant gas discharge communication hole 40b for discharging the oxidant gas are provided.
[0021]
The electrolyte membrane / electrode structure 34 includes, for example, a solid polymer electrolyte membrane 46 in which a perfluorosulfonic acid thin film is impregnated with water, and an anode side electrode 48 and a cathode side electrode 50 that sandwich the solid polymer electrolyte membrane 46. With.
[0022]
The anode side electrode 48 and the cathode side electrode 50 are composed of a gas diffusion layer made of carbon paper or the like, and an electrode catalyst layer in which porous carbon particles having a platinum alloy supported on the surface are uniformly applied to the surface of the gas diffusion layer. Respectively. The electrode catalyst layer is bonded to both surfaces of the solid polymer electrolyte membrane 46.
[0023]
A fuel gas flow path 52 that connects the fuel gas supply communication hole 44 a and the fuel gas discharge communication hole 44 b is formed on the surface 36 a of the first separator 36 facing the electrolyte membrane / electrode structure 34. The fuel gas channel 52 is provided with a plurality of grooves extending in the direction of arrow B, for example. A cooling medium flow path 54 that connects the cooling medium supply communication hole 42 a and the cooling medium discharge communication hole 42 b is formed on the surface 36 b of the first separator 36. The cooling medium flow path 54 is provided with a plurality of grooves extending in the arrow B direction.
[0024]
The surface 38a of the second separator 38 facing the electrolyte membrane / electrode structure 34 is provided with, for example, an oxidant gas flow path 56 including a plurality of grooves extending in the direction of arrow B, and the oxidant gas flow path. 56 communicates with the oxidant gas supply communication hole 40a and the oxidant gas discharge communication hole 40b.
[0025]
As shown in FIG. 2, the intermediate plate 28 is formed of a metal plate material (for example, SUS material) similarly to the first and second separators 36 and 38. Two ends of the intermediate plate 28 in the long-side direction (arrow B direction) and / or both ends in the short-side direction (arrow C direction), respectively, in the first embodiment, A guide member 60 is provided at a predetermined position. The guide member 60 is made of a rectangular plate that is long in the direction of the arrow A, and is fixed to the intermediate plate 28 by welding, bonding, screwing, or the like.
[0026]
The intermediate plate 28 is disposed so as to partition a predetermined number of unit cells 12 in the laminate 14, and the number of the unit cells 12 is set according to the use state, dimensions and materials of various components, and the like. Yes.
[0027]
As shown in FIG. 4, the case member 26 includes a lower plate 64 a, an upper plate 64 b and side plates 64 c and 64 d, which are fixed to the end plates 20 a and 20 b via bolts 66. Four guide grooves 68 are provided on the inner surfaces of the lower plate 64a and the upper plate 64b corresponding to the guide members 60 provided on the two intermediate plates 28, respectively. The guide groove 68 is provided over a predetermined length in the arrow A direction, and the dimension in the arrow B direction (width direction) is set to be substantially the same as the width dimension of the guide member 60. A support mechanism 30 is configured by the guide member 60 and the guide groove 68.
[0028]
As shown in FIG. 1, at one edge of the end plate 20a in the long side direction (arrow B direction), an oxidant gas supply communication hole 40a, a cooling medium supply communication hole 42a, and a fuel gas discharge communication hole 44b communicate with each other. An oxidant gas supply port 80a, a cooling medium supply port 82a, and a fuel gas discharge port 84b are provided. At the other end of the end plate 20a in the long side direction, a fuel gas supply port 84a that communicates with the fuel gas supply communication hole 44a, the cooling medium discharge communication hole 42b, and the oxidant gas discharge communication hole 40b, and a cooling medium discharge port, respectively. 82b and an oxidant gas outlet 80b are provided.
[0029]
The operation of assembling the fuel cell stack 10 configured as described above will be described below.
[0030]
First, a plurality of unit cells 12 are stacked in the direction of arrow A, and a predetermined number, for example, two intermediate plates 28 are interposed to obtain a stacked body 14. Terminal terminal plates 16a and 16b, insulator plates 18a and 18b, and end plates 20a and 20b are disposed at both ends of the laminate 14 in the stacking direction. At that time, the terminal portions 22a and 22b of the terminal terminal plates 16a and 16b are inserted into the cylindrical portions 24a and 24b of the insulator plates 18a and 18b.
[0031]
Therefore, the case member 26 is attached to the end plates 20a and 20b in a state where a predetermined pressing load is applied between the end plates 20a and 20b. In the case member 26, the lower plate 64a, the upper plate 64b, and the side plates 64c and 64d are screwed and fixed to the side portions of the end plates 20a and 20b via bolts 66. For this reason, a predetermined tightening load is applied to the laminate 14 via the case member 26.
[0032]
In this case, in the support mechanism 30, the guide member 60 fixed to each intermediate plate 28 is inserted into a guide groove 68 provided in the lower plate 64a and the upper plate 64b. The guide groove 68 has a width direction dimension substantially the same as the width direction of the guide member 60, and the guide groove 68 has a predetermined length in the direction of arrow A. Therefore, the intermediate plate 28 is supported by the support mechanism 30 so as to be movable back and forth in the stacking direction (arrow A direction) and maintaining parallelism.
[0033]
Next, the operation of the fuel cell stack 10 assembled as described above will be described.
[0034]
First, as shown in FIG. 1, a fuel gas such as a hydrogen-containing gas is supplied from the fuel gas supply port 84a of the end plate 20a into the fuel cell stack 10, and an oxygen-containing gas is supplied from the oxidant gas supply port 80a. An oxidant gas such as is supplied. Further, a cooling medium such as pure water, ethylene glycol, or oil is supplied from the cooling medium supply port 82a. Therefore, in the stacked body 14, the fuel gas, the oxidant gas, and the cooling medium are supplied in series in the arrow A1 direction to the plurality of unit cells 12 that are overlapped in the arrow A direction.
[0035]
As shown in FIG. 3, the oxidant gas is introduced into the oxidant gas flow path 56 of the second separator 38 from the oxidant gas supply communication hole 40 a, and along the cathode side electrode 50 of the electrolyte membrane / electrode structure 34. Moving. On the other hand, the fuel gas is introduced into the fuel gas flow path 52 of the first separator 36 from the fuel gas supply communication hole 44 a and moves along the anode side electrode 48 of the electrolyte membrane / electrode structure 34.
[0036]
Therefore, in each electrolyte membrane / electrode structure 34, the oxidant gas supplied to the cathode side electrode 50 and the fuel gas supplied to the anode side electrode 48 are consumed by an electrochemical reaction in the electrode catalyst layer, Power generation is performed.
[0037]
Next, the fuel gas consumed by being supplied to the anode side electrode 48 is discharged to the fuel gas discharge communication hole 44b, flows in the direction of arrow A2, and then discharged from the fuel gas discharge port 84b of the end plate 20a. Similarly, the oxidant gas consumed by being supplied to the cathode side electrode 50 flows in the direction of arrow A2 along the oxidant gas discharge communication hole 40b, and is then discharged from the oxidant gas discharge port 80b of the end plate 20a. The
[0038]
The cooling medium supplied to the cooling medium supply port 82a is introduced into the cooling medium flow channel 54 of the first separator 36 through the cooling medium supply communication hole 42a, and then circulates in the direction of arrow B. After cooling the electrolyte membrane / electrode structure 34, the cooling medium moves through the cooling medium discharge communication hole 42b in the direction of arrow A2, and is discharged from the cooling medium discharge port 82b of the end plate 20a.
[0039]
In this case, in the first embodiment, an intermediate plate 28 is disposed in the laminated body 14 corresponding to a predetermined number of unit cells 12, and the intermediate plate 28 is connected to a case member via a support mechanism 30. 26 is supported so as to be able to advance and retract in the stacking direction of the unit cells 12 and maintain parallelism.
[0040]
As described above, since the inside of the stacked body 14 is divided into a predetermined number of unit cells 12 via the intermediate plate 28, the shape error of each unit cell 12 is accumulated, and the stacked body 14 is stacked in the stacking direction. There is no risk of tilting. Moreover, the intermediate plate 28 can advance and retreat while maintaining parallelism in the stacking direction under the action of the support mechanism 30. Accordingly, the intermediate plate 28 can follow the expansion and contraction due to the swelling and thermal stress of the laminated body 14 and can reliably prevent the laminated body 14 from being inclined in the laminating direction. For this reason, it becomes possible to improve the straightness of the laminated body 14 and to improve the stability of the dimension of the whole laminated body 14 favorably.
[0041]
In particular, when the first and second separators 36 and 38 constituting each unit cell 12 are constituted by metal thin plates, it is extremely difficult to obtain the parallelism of the first and second separators 36 and 38. At that time, in the first embodiment, the intermediate plate 28 maintains the parallelism, so that the parallelism of each unit cell 12 can be effectively maintained, and the inside of the stacked body 14 is secured at a uniform surface pressure. It becomes possible. Thereby, it is possible to reduce the contact resistance in the laminated body 14 with a simple configuration, to secure a desired sealing property, and to obtain an effect that the power generation performance can be easily improved.
[0042]
Further, the support mechanism 30 includes a plate-shaped guide member 60 fixed to the intermediate plate 28 and a guide groove 68 provided in the case member 26. For this reason, the structure of the support mechanism 30 is effectively simplified, and the support mechanism 30 can be configured to be small and economical.
[0043]
In the first embodiment, two guide members 60 are provided at both ends in the short side direction of the intermediate plate 28, but the present invention is not limited to this. For example, two guide members 60 may be provided at the lower end that is one end in the short side direction of the intermediate plate 28, while one guide member 60 may be provided at the upper end that is the other end in the short side direction. Further, although the support mechanism 30 is provided above and below the case member 26, the support mechanism 30 may be provided on both the left and right sides of the case member 26.
[0044]
FIG. 5 is a schematic perspective view of a fuel cell stack 90 according to the second embodiment of the present invention. The same components as those of the fuel cell stack 10 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. In the third and fourth embodiments described below, detailed description thereof is also omitted.
[0045]
The fuel cell stack 90 includes a support mechanism 92. The support mechanism 92 includes a disc-shaped guide member 94 provided at a predetermined number, for example, two at both ends in the long side direction and / or both ends in the short side direction of the intermediate plate 28, and the case member 26. A guide groove 96 that is long in the stacking direction (arrow A direction) corresponding to the guide member 94 is provided on the inner surface. The guide groove 96 is set to have a width dimension substantially the same as the diameter of the guide member 94, and the guide member 94 is moved in the arrow B direction in a state where the guide member 94 is fitted in the guide groove 96. Be regulated.
[0046]
In the second embodiment configured as described above, the intermediate plate 28 can advance and retract while maintaining parallelism in the stacking direction under the action of the support mechanism 92. For this reason, the surface pressure in the laminated body 14 is maintained uniformly, the contact resistance can be reduced with a simple configuration, and a desired sealing property can be secured. Is obtained.
[0047]
FIG. 6 is a schematic perspective view of a fuel cell stack 100 according to the third embodiment of the present invention.
[0048]
The fuel cell stack 100 includes a support mechanism 102. The guide member 104 constituting the support mechanism 102 has a shaft portion 106a fixed to the intermediate plate 28, and the guide member 104 is configured by providing a disk portion 106b on the shaft portion 106a. The case member 16 is formed with an opening (guide groove) 108 for guiding the shaft portion 106a in the arrow A direction. The disc part 106b of the guide member 104 protrudes outside the case member 26, and the shaft part 106a is fixed to the intermediate plate 28 by, for example, screwing or the like while being inserted into the opening part 108.
[0049]
In the third embodiment configured as described above, the guide member 104 can advance and retreat in the stacking direction under the guiding action of the shaft portion 106a and the opening 108, and maintain the parallelism of the intermediate plate 28. be able to. Therefore, in the third embodiment, the same effect as in the first and second embodiments can be obtained. Moreover, it is only necessary to provide the opening 108 in the case member 26. As a result, the thickness of the case member 26 can be effectively reduced, and the fuel cell stack 100 as a whole can be easily reduced in size.
[0050]
FIG. 7 is a schematic perspective view of a fuel cell stack 110 according to the fourth embodiment of the present invention.
[0051]
The fuel cell stack 110 includes a support mechanism 112. A rectangular guide member 114 constituting the support mechanism 112 is fixed to the intermediate plate 28. The case member 26 is formed with an opening 116 extending in the arrow A direction. The width of the opening 116 is set to be approximately the same as the width of the guide member 114. Guide bars 118 a and 118 b extending in the direction of arrow A are fixed to the outer surface of the case member 26 so as to support both ends in the width direction of the guide member 114.
[0052]
In the fourth embodiment configured as described above, the guide member 114 fixed to the intermediate plate 28 can advance and retreat in the direction of arrow A under the guiding action of the two guide bars 118a and 118b. The intermediate plate 28 can maintain flatness. As a result, the contact resistance in the laminated body 14 can be reduced, and a desired sealing property can be secured, and the thickness of the entire case member 26 can be easily reduced.
[0053]
【The invention's effect】
Since the fuel cell stack according to the present invention is divided into a predetermined number of unit cells via the intermediate plate in the stacked body, there is a possibility that the shape error of each unit cell is accumulated and the stacked body is inclined in the stacking direction. Absent. Moreover, the intermediate plate can advance and retreat while maintaining parallelism in the stacking direction under the action of the support mechanism. Therefore, the intermediate plate can follow the expansion and contraction due to the swelling and thermal stress of the laminated body, and can reliably prevent the laminated body from being inclined in the laminating direction, and the surface pressure in the laminated body can be made uniform. It becomes possible to maintain. Accordingly, the contact resistance in the laminate can be reduced with a simple configuration, and a desired sealing property can be ensured to easily improve the power generation performance.
[Brief description of the drawings]
FIG. 1 is a schematic overall perspective view of a fuel cell stack according to a first embodiment of the present invention.
FIG. 2 is a partial cross-sectional side view of the fuel cell stack.
FIG. 3 is an exploded perspective view of unit cells constituting the fuel cell stack.
FIG. 4 is a perspective explanatory view of an intermediate plate, a support mechanism, and a case member constituting the fuel cell stack.
FIG. 5 is a schematic perspective view of a fuel cell stack according to a second embodiment of the present invention.
FIG. 6 is a schematic perspective view of a fuel cell stack according to a third embodiment of the present invention.
FIG. 7 is a schematic perspective view of a fuel cell stack according to a fourth embodiment of the present invention.
8 is an internal schematic explanatory diagram of a fuel cell of Patent Document 1. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10, 90, 100, 110 ... Fuel cell stack 12 ... Unit cell 14 ... Laminated body 20a, 20b ... End plate 26 ... Case member 28 ... Intermediate plate 30, 92, 102, 112 ... Support mechanism 34 ... Electrolyte membrane and electrode structure Body 36, 38 ... Separator 60, 94, 104, 114 ... Guide member 64a ... Lower plate 64b ... Upper plate 64c, 64d ... Side plate 68, 96 ... Guide groove 106a ... Shaft portion 106b ... Disc portion 108, 116 ... Opening 118a, 118b ... guide bar

Claims (2)

A unit cell in which an electrolyte / electrode structure provided with electrodes on both sides of the electrolyte is sandwiched by separators is provided, and a plurality of the unit cells are stacked to form a stack, and the stack is accommodated in a case member. A fuel cell stack,
A pair of end plates disposed at both ends in the stacking direction of the stacked body and fixed integrally to the case member;
In the laminated body, an intermediate plate disposed corresponding to a predetermined position in the laminating direction;
A support mechanism for supporting the intermediate plate with respect to the case member so as to be movable back and forth in the stacking direction of the unit cells and maintaining parallelism in the stacking direction;
A fuel cell stack comprising: The fuel cell stack according to claim 1, wherein the support mechanism includes a guide member fixed to the intermediate plate;
A guide groove provided in the case member for guiding the guide member in the stacking direction;
A fuel cell stack comprising:

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