JP4862258B2 - Flat type polymer electrolyte fuel cell separator - Google Patents

Description

  The present invention relates to a fuel cell, and more particularly to a separator for a planar polymer electrolyte fuel cell.

A fuel cell is simply a device that continuously supplies fuel (reducing agent) and oxygen or air (oxidant) from the outside, and reacts electrochemically to extract electrical energy. It is classified by type, use, etc. In recent years, depending on the type of electrolyte used, it is largely divided into solid oxide fuel cells, molten carbonate fuel cells, phosphoric acid fuel cells, polymer electrolyte fuel cells, and alkaline aqueous fuel cells. Generally, it is classified into 5 types.
These fuel cells use hydrogen gas generated from methane or the like as a fuel. Recently, a direct methanol fuel cell (hereinafter also referred to as DMFC) that directly uses an aqueous methanol solution as a fuel is also known. Yes.
In particular, a polymer electrolyte fuel cell (hereinafter also referred to as PEFC) having a structure in which a solid polymer membrane is sandwiched between two kinds of electrodes and these members are sandwiched between separators has attracted attention.

In this PEFC, a stack structure is generally used in which a plurality of unit cells each having an electrode are stacked on both sides of a solid polymer film, and the electromotive force is increased according to the purpose. In general, the separator disposed between the unit cells is provided with a fuel gas supply groove for supplying fuel gas to the adjacent unit cell on the side surface. In such a separator, fuel gas and oxidant gas are supplied along the separator surface.
As PEFC separators, a graphite plate is cut and grooved, a carbon compound mold separator made by kneading carbon into a resin, a metal separator that is grooved by etching, etc. A separator or the like in which is covered with a corrosion-resistant resin is known. Each of these separators is formed with a groove for supplying fuel gas and / or a groove for supplying oxidant gas as required.

In addition to this stack structure fuel cell, there is a case where it is required to be as thin as possible with a flat type without requiring an electromotive force as much as a fuel cell for a portable terminal, for example. However, in the case of a planar type in which a plurality of unit cells are arranged in a plane and these are electrically connected in series, there is a problem that the supply of fuel and oxygen becomes uneven depending on the location.
Therefore, in order to improve the non-uniformity of the fuel supply, a large number of through holes are formed in the direction perpendicular to the surface of the separator in contact with the membrane electrode assembly (MEA). A separator having a structure for supplying oxygen has been considered (Patent Document 1).
In the present invention, a composite including an electrode portion positioned between the fuel supply side separator and the oxygen supply side separator of the fuel cell, for example, a current collector layer, a fuel electrode, a polymer electrolyte, oxygen A composite such as a film in which electrodes and current collector layers are laminated is called a membrane electrode composite (MEA).
JP 2003-203647 A

However, in the separator having the above structure, it is difficult to form wiring for electrically connecting unit cells in series, the process is complicated, and there is a problem that contact resistance is increased due to wiring connection. there were.
The present invention has been made in view of the above circumstances, and is a lightweight separator that can be easily connected in series between unit cells without increasing the internal resistance of the battery by contact resistance. The purpose is to provide.

In order to achieve such an object, the present invention has a plurality of through holes for allowing fuel or oxygen to pass through in a separator for a planar type polymer electrolyte fuel cell in which unit cells are arranged in a plane. A current collector portion in which unit conductive substrates are arranged in a plane (n is an integer of 2 or more) through a gap portion, and n openings corresponding to the arrangement positions of the unit conductive substrates. A fuel supply side separator and an oxygen supply side separator provided with a pair of insulating frames integrated so as to sandwich the current collector, and the collector of one of the fuel supply side separator and the oxygen supply side separator. Among the n unit conductive substrates constituting the electric part, each of the unit conductive substrates from the first to (n-1) th one end in the arrangement direction, the fuel supply side separator, and the oxygen supply side separator Before the other Of the n unit conductive substrates constituting the current collector, each of the second to nth unit conductive substrates at one end in the arrangement direction is (n−1) hinge portions for connection. are sequentially connected via a bent in the connecting hinges, and the fuel supply-side separator and the oxygen supply side separator was opposable der so that structure so as to sandwich the membrane electrode assembly.

  As another aspect of the present invention, one of the fuel supply side separator and the oxygen supply side separator is the first unit at one end in the arrangement direction among n unit conductive substrates constituting the current collector ( The n-1) th unit conductive substrate has a projecting member projecting in the direction of the adjacent unit conductive substrate at the corner, and the second to nth units at the end in the arrangement direction A conductive substrate corresponds to the projecting member of the unit conductive substrate adjacent to the upstream side in the arrangement direction, and a notch portion having a shape in which a gap is formed between the projecting member and the projecting member is formed at the corner. (N-1) unit conductive substrates having the projecting members each provided with the connecting hinge portion protruding in a direction substantially orthogonal to the arrangement direction of the unit conductive substrates, The fuel supply side separator and the (n-1) connecting hinge portions Among the n unit conductive substrates constituting the other current collector of the oxygen supply side separator, the second to nth unit conductive substrates at one end in the arrangement direction are attached to the projecting member. It was set as the structure connected.

  As another aspect of the present invention, each of n unit conductive substrates constituting a current collector of a fuel supply side separator and n unit conductive substrates constituting a current collector of an oxygen supply side separator, It was set as the structure which is equipped with the electrode terminal in the unit electroconductive board | substrate which is located in the edge part of an arrangement | sequence direction and the said connection hinge part is not connected.

  The separator of the present invention has one unit cell when the fuel supply side separator and the oxygen supply side separator are bent and integrated with each other so as to sandwich the membrane electrode assembly (MEA) of the fuel cell. The projecting member of the unit conductive substrate of one separator constituting the projecting unit projects into an adjacent unit cell region, and this projecting member is connected to the unit conductive substrate of the other separator of the adjacent unit cell and the hinge portion for connection The n unit cells are electrically connected in series without forming a wiring, and the fuel cell thus obtained has no contact resistance at the connection portion. Therefore, the effect that the internal resistance is low, lightweight and thin is achieved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a perspective view showing an embodiment of a separator for a planar polymer electrolyte fuel cell according to the present invention, and FIG. 2 is a cross-sectional view taken along line AA of the separator shown in FIG. FIG. 3 is a perspective view showing a state in which each member constituting the separator shown in FIG. 1 is separated. 1 to 3, a separator 1 for a planar polymer electrolyte fuel cell according to the present invention includes a fuel supply side separator 11 and an oxygen supply side separator 21. In the present invention, the fuel supply side separator 11 and the oxygen supply side separator 21 will be described for the sake of convenience, but any of them may be a fuel supply side separator or an oxygen supply side separator. Moreover, in FIGS. 1-3, let the direction shown by the arrow a be an arrangement direction of the unit conductive substrate mentioned later.

  The fuel supply side separator 11 includes a current collector 12 in which three rectangular unit conductive substrates 12A, 12B, and 12C having a plurality of through holes 12a are arranged in a plane via a gap 17, and the current collector 12 And a pair of insulating frames 15 and 16 integrated so as to sandwich the portion 12. The insulating frames 15 and 16 have three openings 15A, 15B and 15C and 16A, 16B and 16C corresponding to the arrangement positions of the unit conductive substrates 12A, 12B and 12C, respectively. Each of the openings 15A, 15B, 15C and 16A, 16B, 16C has a structure in which unit conductive substrates 12A, 12B, 12C in which a plurality of through holes 12a are formed are exposed.

  The oxygen supply-side separator 21 also includes a current collector 22 in which three rectangular unit conductive substrates 22A, 22B, and 22C having a plurality of through holes 22a are arranged in a plane via a gap 27, and And a pair of insulating frames 25 and 26 which are integrated so as to sandwich the current collector 22. Each insulating frame 25, 26 has three openings 25A, 25B, 25C and 26A, 26B, 26C corresponding to the arrangement positions of the unit conductive substrates 22A, 22B, 22C, respectively. Each of the openings 25A, 25B, 25C and 26A, 26B, 26C has a structure in which unit conductive substrates 22A, 22B, 22C having a plurality of through holes 22a are exposed.

  In the fuel supply-side separator 11, among the three rectangular unit conductive substrates constituting the current collector 12, the first to second one end portions (right side in the drawing) in the arrangement direction (arrow a direction). The unit conductive substrates 12A and 12B up to the th have protruding members 13 protruding in the direction of the adjacent unit conductive substrates (12B and 12C) at the corners. Further, the second to third unit conductive substrates 12B and 12C at the end (right side in the drawing) in the arrangement direction (arrow a direction) are adjacent to the unit conductive substrates (12A and 12B) adjacent to the upstream side in the arrangement direction. A notch portion 14 having a shape corresponding to the projecting member 13 is provided at a corner so as to leave a gap 18 between the projecting member 13 and the projecting member 13.

Further, the unit conductive substrates 22A, 22B, and 22C constituting the oxygen supply side separator 21 are unit conductive substrates 12A, 12B, and 12B, except that the protruding member 13 and the cutout portion 14 are not formed. The current collecting part 22 is configured in the same shape as that of 12C and arranged through gaps 27 having the same size.
Further, the unit conductive substrates 12A and 12B of the current collector 12 constituting the fuel supply side separator 11 protrude in a direction substantially perpendicular to the arrangement direction (arrow a direction) of the unit conductive substrates 12A, 12B and 12C. Each overhanging member 13 is provided with a connecting hinge portion 31 to be connected. And among these three unit conductive substrates 22A, 22B, 22C constituting the current collector 22 of the oxygen supply side separator 21 via the two connection hinges 31, the arrangement direction (direction of arrow a) The second to third unit conductive substrates 22B and 22C at the end of the unit are connected to the protruding members 13 of the unit conductive substrates 12A and 12B, respectively.

In addition, the current collector 12 constituting the fuel supply side separator 11 is located at the end of the three unit conductive substrates 12A, 12B, and 12C in the arrangement direction (arrow a direction) and is stretched. An electrode terminal 19 is provided on the unit conductive substrate 12 </ b> C that does not have the output member 13. On the other hand, the current collector 22 constituting the oxygen supply side separator 21 is located at the end of the three unit conductive substrates 22A, 22B, and 22C in the arrangement direction (the direction of arrow a), and the connection hinge An electrode terminal 29 is provided on the unit conductive substrate 22A to which the part 31 is not connected.
As the conductive material used for the unit conductive substrates 12A, 12B, 12C constituting the current collector 12 and the unit conductive substrates 22A, 22B, 22C constituting the current collector 22, electric conductivity is good. Those having a predetermined strength and good workability are preferable, and examples thereof include stainless steel, cold-rolled steel plate, aluminum, copper, and titanium.

The unit conductive substrates 12A, 12B, and 12C may include a protective layer made of a corrosion-resistant (acid-resistant) and electrically conductive resin layer at least on the surface portion on the electrolyte side of the fuel cell. As a method for forming such a protective layer, a method of forming a film by electrodeposition using a material in which a conductive material such as carbon particles and corrosion-resistant metal is mixed in a resin and then heat-curing, or a conductive polymer is used. The method of forming the film | membrane of the state which contained the dopant which improves electroconductivity in the resin to be formed by electrolytic polymerization etc. is mentioned.
Further, the surface of the unit conductive substrates 12A, 12B, and 12C may be subjected to a plating treatment such as gold plating to provide a corrosion-resistant metal layer without impairing the conductivity. Furthermore, a protective layer having acid resistance and electrical conductivity may be disposed on such a corrosion-resistant metal layer.
The connecting hinge 31 may be covered with an insulating resin to provide an insulating coating.

Each of the unit conductive substrates 12A, 12B, 12C, 22A, 22B, and 22C is processed into a predetermined shape by machining and etching using a photolithography technique, and includes an overhang member 13 and a notch 14. The through holes 12a and 22a for supplying fuel or supplying oxygen are formed by these methods.
The material of the pair of insulating frames 15 and 16 constituting the fuel supply side separator 11 and the pair of insulating frames 25 and 26 constituting the oxygen supply side separator 21 is insulative and has good workability. It is preferable to be light and have high mechanical strength. As such a material, a substrate material for a printed wiring board is used, and examples thereof include glass epoxy and polyimide. The insulating frames 15, 16, 25, and 26 having a desired shape can be formed by machining, laser processing, or the like.

  As a manufacturing method of the fuel supply side separator 11 and the oxygen supply side separator 21, for example, the current collector 12 and the current collector 22 are manufactured in a state of being connected via the connection hinge 31, and thus manufactured. Further, there is a method in which the current collector 12 and the insulating frames 15 and 16 and the current collector 22 and the insulating frames 25 and 26 are fixed while being aligned.

  FIG. 4 is a diagram illustrating an example of the current collector 12 and the current collector 22 that are manufactured in a state of being connected via the connection hinge 31. In FIG. 4, the current collector 12 includes each unit conductive substrate such that three unit conductive substrates 12 </ b> A, 12 </ b> B, 12 </ b> C having a plurality of through holes 12 a are arranged in a plane via the gaps 17. 12A, 12B, and 12C are supported on the outer frame body 41 via a plurality of ribs. In addition, the current collector 22 includes each unit conductive substrate 22A, 22A, 22B, 22C having a plurality of through-holes 22a arranged in a plane via the gap 27. 22B and 22C are supported on the outer frame body 41 via a plurality of ribs. The projecting members 13 of the unit conductive substrates 12A and 12B and the unit conductive substrates 22B and 22C are connected by the connecting hinges 31, respectively.

The insulating frames 15 and 16 are fixed to the unit conductive substrates 12A, 12B, and 12C as described above while being aligned, and the insulating frames 25 and 26 are fixed to the unit conductive substrates 22A, 22B, and 22C. The present invention is composed of the fuel supply side separator 11 and the oxygen supply side separator 21 connected by the connecting hinge 31 by cutting the rib 42 and then removing the outer frame body 41 by fixing while aligning. The separator 1 is obtained.
The fixing of each member includes, for example, a method in which an adhesive such as an epoxy resin or a polyimide resin is applied or laminated and the adhesive is cured and fixed in a state where the members are overlapped. The adhesive used in this case is not particularly limited as long as it does not affect other members in the manufacturing process and has excellent resistance to operating conditions when used in a fuel cell. .
In addition, there is a method in which a part or all of the insulating frames 15, 16, 25, and 26 are formed of a semi-cured prepreg, and are crimped to the current collectors 12 and 22 to be fixed.

  In the separator 1 of the present invention described above, since the predetermined unit conductive substrates constituting the fuel supply side separator 11 and the oxygen supply side separator 21 are connected by the connecting hinge portion 31, there is no complicated wiring, In combination with strength and weight reduction, when used in a flat polymer electrolyte fuel cell, the connecting hinge portion 31 is bent to sandwich the fuel cell membrane electrode assembly (MEA). Thus, it is possible to easily produce a planar polymer electrolyte fuel cell having a plurality of unit cells electrically connected in series.

The separator of the present invention described above is an example and is not limited thereto. For example, the fuel supply side separator and the oxygen supply side separator shown in FIGS. 1 to 4 are separators in which three unit conductive substrates are arranged, but have two or four or more unit conductive substrates. Is the same.
Further, as shown in FIG. 5, the unit conductive substrates 12 </ b> A and 12 </ b> B and the unit conductive substrates 22 </ b> B and 22 </ b> C may be sequentially connected by two connecting hinge portions 31. In this case, the unit conductive substrates 12A and 12B do not include the overhanging member 13, and the unit conductive substrates 12B and 12C do not include the notch portion 14.

Further, the gap 17 that exists between the unit conductive substrates 12A, 12B, and 12C of the fuel supply side separator 11, and the gap that exists between the unit conductive substrates 22A, 22B, and 22C of the oxygen supply side separator 21. 27 may be filled with an insulating material, for example, an adhesive such as epoxy resin or fluorine resin.
Further, the openings 15A, 15B, 15C and the openings 25A, 25B, 25C of the insulating frames 15, 25 may be configured as a set of a plurality of openings, respectively.
Furthermore, for example, when the separator of the present invention is used in a planar polymer electrolyte fuel cell, the openings 16A and 16B of the insulating frames 16 and 26 located on the membrane electrode assembly (MEA) side are provided. , 16C, 26A, 26B, 26C are provided with a gas diffusion layer or a catalyst layer so as to cover the unit conductive substrates 12A, 12B, 12C, 22A, 22B, 22C of the current collectors 12, 22. Also good.

The gas diffusion layer is made of a porous current collector, and for example, carbon fiber, alumina or the like can be used. The thickness of the gas diffusion layer can be appropriately set within a range of about 20 to 500 μm, for example.
The catalyst layer becomes a fuel electrode when the separator is used as a fuel supply side separator, and becomes an oxygen electrode when the separator is used as an oxygen supply side separator. Examples of the material for such a catalyst layer include platinum, gold, palladium, ruthenium, copper, platinum oxide, tungsten oxide, iron, nickel, rhodium, and the like. These may be used alone or in combination of two or more. Can be used in combination. Moreover, the thickness of a catalyst layer can be suitably set, for example in the range of about 10-300 micrometers.

Next, an example of a planar polymer electrolyte fuel cell using the separator of the present invention will be described.
FIG. 6 is a block diagram showing an example of a flat polymer electrolyte fuel cell incorporating the separator 1 of the present invention comprising the fuel supply side separator 11 and the oxygen supply side separator 21 as described above. FIG. 7 is a view showing a state in which the respective members of the planar polymer electrolyte fuel cell shown in FIG. 6 are separated.
6 and 7, a polymer electrolyte fuel cell 51 is sandwiched between a fuel supply side separator 11 and an oxygen supply side separator 21 in which a membrane electrode assembly (MEA) 64 constitutes a pair of separators 1 of the present invention. A battery body 61 and a case body 62 are provided.

  In the battery body 61, the separator 1 is bent at the connection hinge portion 31, and the insulating frames 16 and 26 of the fuel supply side separator 11 and the oxygen supply side separator 21 face the membrane electrode assembly (MEA) 64. Are arranged as follows. The current collectors 12 and 22 of the fuel supply side separator 11 and the oxygen supply side separator 21 are in contact with the membrane electrode assembly (MEA) 64 through the carbon paper 63. The membrane electrode assembly (MEA) 64 includes a fuel electrode side catalyst layer 65 on the fuel supply side separator 11 side, and an oxygen electrode side catalyst layer 66 on the oxygen supply side separator 21.

Thus, the three unit cells 61A, 61B, 61C are arranged in a plane. The current collector 12 (unit conductive substrates 12A, 12B, 12C) and the current collector 22 (unit conductive substrates 22A, 22B, 22C) between the three unit cells 61A, 61B, 61C are connected to the hinges for connection. The part 31 and the overhang member 13 are electrically connected.
Here, the connecting hinge portion 31 may be covered with an insulating resin to provide an insulating coating.
In the battery body 61 described above, both ends of the membrane electrode assembly (MEA) 64 are sandwiched between a pair of separator outer peripheral frame members 71A and 71B via a seal member 75. The battery body 61 is fixed to the case body 62 via a seal member 75 using fixing bolts 77.

The separator outer peripheral frame member 71A includes an electrode terminal 29 connected to the unit conductive substrate 22A of the oxygen supply side separator 21 constituting the unit cell 61A. Further, the separator outer peripheral frame member 71B includes an electrode terminal 19 connected to the unit conductive substrate 12C of the fuel supply side separator 11 constituting the unit cell 61C. As a result, the three unit cells 61A, 61B, 61C are electrically connected in series as follows.
Electrode terminal 29 → *
* → unit cell 61A [unit conductive substrate 22A of separator 21 → membrane electrode assembly (MEA) 64 → unit conductive substrate 12A of separator 11 → projecting member 13]
→ Connecting hinge 31 → *
* → unit cell 61B [unit conductive substrate 22B of separator 21 → membrane electrode assembly (MEA) 64 → unit conductive substrate 12B of separator 11 → projecting member 13]
→ Connecting hinge 31 → *
* → Unit cell 61C [Unit conductive substrate 22C of separator 21 → Membrane electrode composite
(MEA) 64 → the unit conductive substrate 12C of the separator 11] → *
* → Electrode terminal 19

  In such a polymer electrolyte fuel cell 51, three unit cells 61A, 61B, and 61C are connected by the connecting hinge portion 31, and a connection step using a connecting member is not required separately, and contact resistance is provided. There is very little power generation characteristics.

  The separator of the present invention can be used in a planar polymer electrolyte fuel cell, and a lightweight and thin direct methanol fuel cell can be realized.

It is a perspective view which shows one Embodiment of the separator for planar type polymer electrolyte fuel cells of this invention. It is AA arrow sectional drawing of the separator shown by FIG. It is a perspective view which shows the state which spaced apart each member which comprises the separator shown by FIG. It is a figure which shows an example of the current collection part used for preparation of a separator. It is a figure which shows the other example of the current collection part used for preparation of a separator. It is a block diagram which shows an example of the planar type polymer electrolyte fuel cell using the separator of this invention. It is a figure which shows the state which spaced apart each member of the planar type polymer electrolyte fuel cell shown by FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Separator for polymer electrolyte type fuel cells 11 ... Fuel supply side separator 12 ... Current collecting part 12A, 12B, 12C ... Unit conductive substrate 13 ... Overhang member 14 ... Notch part 15, 16 ... Insulating frame 17.18 ... Air gap part 21 ... Oxygen supply side separator 22 ... Current collector part 22A, 22B, 22C ... Unit conductive substrate 25, 26 ... Insulating frame 27 ... Air gap part 31 ... Connecting hinge part 51 ... Polymer electrolyte Type fuel cell 61A, 61B, 61C ... unit cell 64 ... membrane electrode assembly (MEA)

Claims (3)

In a separator for a planar polymer electrolyte fuel cell in which unit cells are arranged in a plane,
A current collecting portion in which n unit conductive substrates having a plurality of through holes for allowing fuel or oxygen to pass therethrough are arranged in a plane via a gap (n is an integer of 2 or more), and the unit conductive substrate A fuel supply side separator and an oxygen supply side separator provided with a pair of insulating frames having n openings corresponding to the arrangement positions of
Of the n unit conductive substrates constituting one of the current collectors of the fuel supply side separator and the oxygen supply side separator, each unit from the first to (n−1) th one end in the arrangement direction Among the n unit conductive substrates constituting the current collector of the other of the conductive substrate and the fuel supply side separator and the oxygen supply side separator, each of the second to nth one end portions in the arrangement direction Unit conductive substrates are sequentially connected via (n-1) connecting hinge portions, bent at the connecting hinge portions, and the fuel supply side separator and the oxygen supply side separator are combined with a membrane electrode. the separator for a polymer electrolyte fuel cell of the planar, wherein opposable der Rukoto so as to sandwich the body. One of the fuel supply side separator and the oxygen supply side separator is a unit from the first to (n-1) th of one end in the arrangement direction among the n unit conductive substrates constituting the current collector. The conductive substrate has a protruding member protruding in the direction of the adjacent unit conductive substrate at the corner, and the second to nth unit conductive substrates at the end in the arrangement direction are arranged upstream in the arrangement direction. Corresponding to the projecting member of the unit conductive substrate adjacent to the side, and has a notch portion in the shape of a gap formed between the projecting member and the corner,
Each of the (n−1) unit conductive substrates having the projecting member includes the connection hinge portion protruding in a direction substantially orthogonal to the arrangement direction of the unit conductive substrates, and each projecting member includes (n− 1) One of the n unit conductive substrates constituting the current collector of the other of the fuel supply side separator and the oxygen supply side separator is connected to one end in the arrangement direction via the connection hinges. 2. The separator for a planar polymer electrolyte fuel cell according to claim 1, wherein second to n-th unit conductive substrates are connected to the projecting member.   The n unit conductive substrates constituting the current collecting part of the fuel supply side separator and the n unit conductive substrates constituting the current collecting part of the oxygen supply side separator are positioned at the ends in the arrangement direction, respectively. 3. A separator for a planar polymer electrolyte fuel cell according to claim 1 or 2, wherein an electrode terminal is provided on a unit conductive substrate to which the connecting hinge portion is not connected. .

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