JP6843730B2 - Fuel cell and its operation method - Google Patents

Description

The present invention relates to a fuel cell in which a frame member is provided on the outer peripheral portion of the electrolyte membrane / electrode structure and an operation method thereof.

Generally, a polymer electrolyte fuel cell employs a solid polymer electrolyte membrane made of a polymer ion exchange membrane. A fuel cell includes an electrolyte membrane / electrode structure (MEA) in which an anode electrode is arranged on one surface of a solid polymer electrolyte membrane and a cathode electrode is arranged on the other surface of the solid polymer electrolyte membrane.

The electrolyte membrane / electrode structure is sandwiched between separators (bipolar plates) to form a power generation cell (unit fuel cell). The power generation cells are used as, for example, an in-vehicle fuel cell stack by stacking a predetermined number of the power generation cells.

In recent years, in order to reduce the amount of relatively expensive solid polymer electrolyte membrane used and to protect the thin-film, low-strength solid polymer electrolyte membrane, a framed MEA incorporating a resin frame member on the outer circumference has been adopted. (See, for example, Patent Document 1).

International Publication No. 2012/137609

By the way, in the MEA with a frame, the inner peripheral portion of the frame member is joined to the electrolyte membrane / electrode structure, and the outer peripheral portion of the frame member is sandwiched between the protruding seal portions provided on the pair of separators. In order to bring the seal portion into contact with the frame member, the outer peripheral portion of the frame member needs to be set thicker than the inner peripheral portion of the frame member. Therefore, it is conceivable to join two frame-shaped sheets having different thicknesses to form a frame-shaped sheet whose outer peripheral portion is thicker than that of the inner peripheral portion. The pressure of the reaction gas supplied to the anode electrode and the reaction gas supplied to the cathode electrode may be different. In this case, it is required that the two frame-shaped sheets do not peel off due to the differential pressure between the reaction gases.

The present invention has been made in consideration of such a problem, and is a reaction gas in a fuel cell in which a frame member formed by joining two frame-shaped sheets is provided on the outer peripheral portion of an electrolyte membrane / electrode structure. The purpose is to prevent the two frame-shaped sheets from peeling off due to the differential pressure between them.

In order to achieve the above object, the present invention comprises an electrolyte membrane / electrode structure in which a first electrode and a second electrode are provided on both sides of the electrolyte membrane, and the first electrode side of the electrolyte membrane / electrode structure. A first separator laminated on the first electrode and a second separator laminated on the second electrode side of the electrolyte membrane / electrode structure are provided, and a first reaction gas is supplied to the first electrode to supply the second electrode. A frame member that orbits the outer peripheral portion is provided on the outer peripheral portion of the electrolyte membrane / electrode structure, and the inner peripheral portion of the frame member is an electrolyte. It has a first frame-shaped sheet joined to the outer peripheral portion of the film / electrode structure and a second frame-shaped sheet thicker than the first frame-shaped sheet, and the first frame-shaped sheet and the second frame-shaped sheet. The sheets are joined to each other in the thickness direction, the frame member is sandwiched between the first separator and the second separator, and the inner peripheral portion of the first frame-shaped sheet is formed by the first electrode. The inner peripheral end of the second frame-shaped sheet is arranged between the outer peripheral portion and the outer peripheral portion of the second electrode, and is arranged outside the outer peripheral end of the second electrode via a gap. A flow path for passing the first reaction gas set to a pressure higher than the pressure of the second reaction gas is provided between the frame member and the first separator, and the frame member and the second separator are provided. A flow path for passing the second reaction gas is provided between the two.

In the fuel cell, the flow path between the frame member and the first separator allows fuel gas to flow as the first reaction gas, and the flow path between the frame member and the second separator. It is preferable to distribute an oxidizing agent gas as the second reaction gas.

In the above fuel cell, in the first electrode and the second electrode, the plane dimension of one electrode may be set to be larger than the plane dimension of the other electrode.

In the above fuel cell, the first electrode may be set to be larger than the plane dimension of the second electrode.

In the above fuel cell, the position of the outer peripheral end of the electrolyte membrane may be the same as the outer peripheral end of the other electrode.

In the above fuel cell, the inner peripheral portion of the first frame-shaped sheet may be arranged between the electrolyte membrane and the first electrode.

In the above fuel cell, in the first electrode and the second electrode, one of the electrodes is formed on the electrolyte membrane between a region overlapping the electrolyte membrane and a region overlapping the inner peripheral portion of the first frame-shaped sheet. The other electrode has an inclined region that is inclined with respect to the electrode, and is formed flat from a region that overlaps the electrolyte membrane to a region that overlaps the inner peripheral portion of the first frame-shaped sheet, and is an outer peripheral portion of the electrolyte membrane. Is preferably arranged between the other electrode and the inner peripheral portion of the first frame-shaped sheet.

In the above fuel cell, it is preferable that an adhesive layer is provided over the entire surface of the surface of the first frame-shaped sheet on the side of the second frame-shaped sheet.

The first separator is provided with a bead seal that bulges toward the frame member side in order to prevent leakage of the first reaction gas, and the second separator prevents leakage of the second reaction gas. Therefore, a bulging bead seal is provided on the frame member side, and the frame member is sandwiched between the bead seal provided on the first separator and the bead seal provided on the second separator. It is good to be there.

Further, in the present invention, the electrolyte membrane / electrode structure in which the first electrode and the second electrode are provided on both sides of the electrolyte membrane and the first electrode structure laminated on the first electrode side of the electrolyte membrane / electrode structure. A separator and a second separator laminated on the second electrode side of the electrolyte membrane / electrode structure are provided, a first reaction gas is supplied to the first electrode, and a second reaction gas is supplied to the second electrode. A method of operating a supplied fuel cell, wherein a frame member that orbits the outer peripheral portion is provided on the outer peripheral portion of the electrolyte membrane / electrode structure, and the inner peripheral portion of the frame member is an electrolyte membrane / electrode. It has a first frame-shaped sheet joined to the outer peripheral portion of the structure and a second frame-shaped sheet thicker than the first frame-shaped sheet, and the first frame-shaped sheet and the second frame-shaped sheet are The frame members are sandwiched between the first separator and the second separator, and the inner peripheral portion of the first frame-shaped sheet is the outer peripheral portion of the first electrode. The inner peripheral end of the second frame-shaped sheet is arranged between the outer peripheral portion of the second electrode and the outer peripheral portion of the second electrode via a gap, and is arranged with the frame member. The first reaction gas having a pressure higher than the pressure of the second reaction gas is supplied to the flow path formed between the first separator and the frame member and the second separator. The second reaction gas is supplied to the flow path.

A fuel gas is circulated as the first reaction gas in the flow path between the frame member and the first separator, and the second reaction is carried out in the flow path between the frame member and the second separator. Oxidizing agent gas should be circulated as gas.

It is preferable that the first electrode is set to be larger than the plane dimension of the second electrode, and the position of the outer peripheral end of the electrolyte membrane is the same as the outer peripheral end of the second electrode.

The first separator includes a first reaction gas flow path for flowing the first reaction gas along the electrode surface of the electrolyte membrane / electrode structure, and the first reaction gas to prevent leakage of the first reaction gas. A bead seal that surrounds the reaction gas flow path and bulges toward the frame member side is formed, and the first reaction gas flow path is formed between a plurality of protrusions protruding toward the electrolyte membrane / electrode structure side. It has a plurality of flow path grooves, the plurality of convex portions are formed at intervals in the flow path width direction of the first reaction gas flow path, and the outer peripheral end of the first electrode is the plurality of convex portions. Of these, it is preferable to be located between the outermost convex portion of the end in the width direction of the flow path and the bead seal.

The second separator includes a second reaction gas flow path for flowing the second reaction gas along the electrode surface of the electrolyte membrane / electrode structure, and the second reaction gas to prevent leakage of the second reaction gas. A bead seal that surrounds the reaction gas flow path and bulges toward the frame member side is formed, and the second reaction gas flow path is formed between a plurality of protrusions protruding toward the electrolyte membrane / electrode structure side. It has a plurality of flow path grooves, the plurality of convex portions are formed at intervals in the flow path width direction of the second reaction gas flow path, and the outer peripheral end of the second electrode is the plurality of convex portions. Of these, it is preferable to be located between the outermost convex portion of the end in the width direction of the flow path and the bead seal.

According to the fuel cell of the present invention and its operation method, the reaction gas is directed from the first frame-shaped sheet side (the side where the gap is not formed) to the second frame-shaped sheet side (the side where the gap is formed). The differential pressure between them acts. Therefore, the differential pressure does not act on the joint surface (bonding surface) between the first frame-shaped sheet and the second frame-shaped sheet. Therefore, it is possible to prevent the first frame-shaped sheet and the second frame-shaped sheet from peeling off due to the differential pressure between the reaction gases.

It is an exploded perspective view of the main part of the power generation cell which constitutes the fuel cell stack which concerns on embodiment of this invention. FIG. 2 is a cross-sectional view taken along the line II-II in FIG. It is an overall schematic diagram of a fuel cell system.

As shown in FIGS. 1 and 2, the power generation cell (fuel cell) 12 is arranged on both sides of the framed electrolyte membrane / electrode structure 10 (hereinafter referred to as “framed MEA10”) and the framed MEA10. A separator 14 and a second separator 16 are provided. The power generation cell 12 is, for example, a horizontally (or vertically long) rectangular solid polymer fuel cell. For example, the plurality of power generation cells 12 are stacked in the arrow A direction (horizontal direction) or the arrow C direction (gravity direction) to form the fuel cell stack 11a. The fuel cell stack 11a is mounted on a fuel cell electric vehicle (not shown) as, for example, an in-vehicle fuel cell stack.

In the power generation cell 12, the framed MEA 10 is sandwiched by the first separator 14 and the second separator 16. The first separator 14 and the second separator 16 have a horizontally long (or vertically long) rectangular shape. The first separator 14 and the second separator 16 are made of, for example, a steel plate, a stainless steel plate, an aluminum plate, a plated steel plate, a metal plate whose metal surface is surface-treated for corrosion protection, a carbon member, or the like.

The rectangular framed MEA 10 includes an electrolyte membrane / electrode structure 10a (hereinafter, referred to as “MEA 10a”). The MEA10a comprises an electrolyte membrane 18, an anode electrode (first electrode) 20 provided on one surface of the electrolyte membrane 18, and a cathode electrode (second electrode) 22 provided on the other surface of the electrolyte membrane 18. Have.

The electrolyte membrane 18 is, for example, a solid polymer electrolyte membrane (cation exchange membrane). The solid polymer electrolyte membrane is, for example, a thin film of perfluorosulfonic acid containing water. The electrolyte membrane 18 is sandwiched between the anode electrode 20 and the cathode electrode 22. As the electrolyte membrane 18, an HC (hydrocarbon) -based electrolyte can be used in addition to the fluorine-based electrolyte.

The anode electrode 20 has a plane dimension (external dimension) larger than that of the electrolyte membrane 18 and the cathode electrode 22. Instead of the above configuration, the anode electrode 20 may be configured to have a plane dimension smaller than that of the electrolyte membrane 18 and the cathode electrode 22.

The anode electrode 20 has a first electrode catalyst layer 20a bonded to one surface 18a of the electrolyte membrane 18 and a first gas diffusion layer 20b laminated on the first electrode catalyst layer 20a. The first electrode catalyst layer 20a and the first gas diffusion layer 20b have the same planar dimensions as each other, and are set to have larger planar dimensions than the electrolyte membrane 18 and the cathode electrode 22.

The cathode electrode 22 has a second electrode catalyst layer 22a bonded to the surface 18b of the electrolyte membrane 18 and a second gas diffusion layer 22b laminated on the second electrode catalyst layer 22a. The second electrode catalyst layer 22a and the second gas diffusion layer 22b have the same planar dimensions as each other and are set to the same planar dimensions as the electrolyte membrane 18. Therefore, in the plane direction of the electrolyte membrane 18 (direction of arrow C in FIG. 2), the outer peripheral end 22e of the cathode electrode 22 is at the same position as the outer peripheral end 18e of the electrolyte membrane 18.

The cathode electrode 22 is set to a plane dimension smaller than that of the anode electrode 20. The outer peripheral end 22e of the cathode electrode 22 and the outer peripheral end 18e of the electrolyte membrane 18 are located inward of the outer peripheral end 20e of the anode electrode 20 over the entire circumference.

The cathode electrode 22 is set to have a plane dimension larger than that of the anode electrode 20, and the outer peripheral end 22e of the cathode electrode 22 may be located outside the outer peripheral end 20e of the anode electrode 20 over the entire circumference. .. Alternatively, the anode electrode 20 and the cathode electrode 22 are set to have the same plane dimensions, and the outer peripheral end 20e of the anode electrode 20 and the outer peripheral end 22e of the cathode electrode 22 are in the plane direction of the electrolyte membrane 18 (direction arrow C in FIG. 2). ), They may be in the same position.

The first electrode catalyst layer 20a is formed, for example, by uniformly coating the surface of the first gas diffusion layer 20b together with porous carbon particles on which a platinum alloy is supported on the surface together with an ion conductive polymer binder. The second electrode catalyst layer 22a is formed, for example, by uniformly coating the surface of the second gas diffusion layer 22b with porous carbon particles on which a platinum alloy is supported on the surface together with an ion conductive polymer binder.

The first gas diffusion layer 20b and the second gas diffusion layer 22b are formed of carbon paper, carbon cloth, or the like. The plane dimension of the second gas diffusion layer 22b is set smaller than the plane dimension of the first gas diffusion layer 20b. The first electrode catalyst layer 20a and the second electrode catalyst layer 22a are formed on both surfaces of the electrolyte membrane 18, respectively.

The framed MEA 10 orbits the outer circumference of the electrolyte membrane 18 over the entire circumference, and further includes a frame member 24 joined to the anode electrode 20 and the cathode electrode 22. The frame member 24 has two frame-shaped sheets having different thicknesses. Specifically, the frame member 24 has a first frame-shaped sheet 24a in which the inner peripheral portion 24an is joined to the outer peripheral portion of the MEA 10a, and a second frame-shaped sheet 24b in which the inner peripheral portion 24an is joined to the first frame-shaped sheet 24a. .. The first frame-shaped sheet 24a and the second frame-shaped sheet 24b are joined to each other in the thickness direction by an adhesive layer 24c made of an adhesive. The second frame-shaped sheet 24b is joined to the outer peripheral portion of the first frame-shaped sheet 24a. As a result, the outer peripheral portion of the frame member 24 is made thicker than the inner peripheral portion of the frame member 24.

The first frame-shaped sheet 24a and the second frame-shaped sheet 24b are made of a resin material. Examples of the constituent materials of the first frame-shaped sheet 24a and the second frame-shaped sheet 24b include PPS (polyphenylene sulfide), PPA (polyphthalamide), PEN (polyethylene terephthalate), PES (polyether sulfone), and LCP. (Liquid crystal polymer), PVDF (polyvinylidene fluoride), silicone resin, fluororesin, m-PPE (modified polyphenylene ether resin), PET (polyethylene terephthalate), PBT (polybutylene terephthalate), modified polyolefin and the like can be mentioned.

The inner peripheral portion 24an of the first frame-shaped sheet 24a is arranged between the outer peripheral portion 20c of the anode electrode 20 and the outer peripheral portion 22c of the cathode electrode 22. Specifically, the inner peripheral portion 24an of the first frame-shaped sheet 24a is sandwiched between the outer peripheral portion 18c of the electrolyte membrane 18 and the outer peripheral portion 20c of the anode electrode 20. The inner peripheral portion 24an of the first frame-shaped sheet 24a and the outer peripheral portion 18c of the electrolyte membrane 18 are joined via the adhesive layer 24c. The inner peripheral portion 24an of the first frame-shaped sheet 24a may be sandwiched between the electrolyte membrane 18 and the cathode electrode 22.

The anode electrode 20 described above is provided with a step at a position corresponding to the inner peripheral end 24ae of the first frame-shaped sheet 24a. Specifically, the anode electrode 20 has an inclined region 21c inclined with respect to the electrolyte membrane 18 between a region 21a overlapping the inner peripheral portion 24an of the first frame-shaped sheet 24a and a region 21b overlapping the electrolyte membrane 18. .. Therefore, in the inclined region 21c, the first electrode catalyst layer 20a and the first gas diffusion layer 20b are inclined with respect to the electrolyte membrane 18.

In the anode electrode 20, the surface of the region 21a overlapping the inner peripheral portion 24an of the first frame-shaped sheet 24a on the first separator 14 side is an electrolyte membrane rather than the surface of the region 21b overlapping the electrolyte membrane 18 on the first separator 14 side. It is located away from 18.

On the other hand, the cathode electrode 22 is formed flat from the region 23b overlapping the electrolyte membrane 18 to the region 23a overlapping the inner peripheral portion 24an of the first frame-shaped sheet 24a. Therefore, the second electrode catalyst layer 22a and the second gas diffusion layer 22b are parallel to the electrolyte membrane 18 from the region 23b overlapping the electrolyte membrane 18 to the region 23a overlapping the inner peripheral portion 24an of the first frame-shaped sheet 24a. is there.

Unlike the above configuration, the anode electrode 20 is formed flat from the region 21b overlapping the electrolyte membrane 18 to the region 21a overlapping the inner peripheral portion 24an of the first frame-shaped sheet 24a, and the cathode electrode 22 is the electrolyte. An inclined region inclined with respect to the electrolyte membrane 18 may be provided between the region 23b overlapping the film 18 and the region 23a overlapping the inner peripheral portion 24an of the first frame-shaped sheet 24a.

The second frame-shaped sheet 24b is joined to the outer peripheral portion of the first frame-shaped sheet 24a. The thickness T2 of the second frame-shaped sheet 24b is thicker than the thickness T1 of the first frame-shaped sheet 24a. As a result, the outer peripheral portion of the frame member 24 becomes thicker, so that the bead seal can be used for good sealing. The inner peripheral end 24be of the second frame-shaped sheet 24b is located outside the inner peripheral end 24ae of the first frame-shaped sheet 24a (in the direction away from the MEA 10a), and the outer peripheral end 20e of the anode electrode 20 and the cathode electrode 22 It is located outside the outer peripheral end 22e of. A gap G is formed between the inner peripheral end 24be of the second frame-shaped sheet 24b and the outer peripheral end 22e of the cathode electrode 22. The gap G constitutes a part of the flow path 36a described later.

The adhesive layer 24c is provided on the entire surface of the first frame-shaped sheet 24a on the surface 24as on the second frame-shaped sheet 24b side (cathode side). The first frame-shaped sheet 24a is exposed to the gap G (flow path 36a) via the adhesive layer 24c at the above-mentioned gap G. As the adhesive constituting the adhesive layer 24c, for example, a liquid adhesive or a hot melt sheet is provided. The adhesive is not limited to liquids, solids, thermoplastics, thermosettings, and the like.

As shown in FIG. 1, one end edge of the power generation cell 12 in the arrow B direction (horizontal direction) communicates with each other in the direction of arrow A, which is the stacking direction, to communicate with the oxidant gas inlet communication hole 30a and the cooling medium inlet. The hole 32a and the fuel gas outlet communication hole 34b are provided. The oxidant gas inlet communication hole 30a supplies an oxidant gas, for example, an oxygen-containing gas, while the cooling medium inlet communication hole 32a supplies a cooling medium. The fuel gas outlet communication hole 34b discharges a fuel gas, for example, a hydrogen-containing gas. The oxidant gas inlet communication hole 30a, the cooling medium inlet communication hole 32a, and the fuel gas outlet communication hole 34b are arranged in the arrow C direction (vertical direction).

At the other end of the power generation cell 12 in the arrow B direction, a fuel gas inlet communication hole 34a that communicates with each other in the arrow A direction to supply fuel gas, a cooling medium outlet communication hole 32b that discharges the cooling medium, and oxidation An oxidant gas outlet communication hole 30b for discharging the agent gas is provided. The fuel gas inlet communication hole 34a, the cooling medium outlet communication hole 32b, and the oxidant gas outlet communication hole 30b are arranged in the direction of arrow C.

An oxidant gas flow path 36 communicating with the oxidant gas inlet communication hole 30a and the oxidant gas outlet communication hole 30b is provided on the surface 16a of the second separator 16 toward the framed MEA 10. Specifically, the oxidant gas flow path 36 is formed between the second separator 16 and the framed MEA 10. The oxidant gas flow path 36 has a plurality of flow path grooves 36r extending in the direction of arrow B. The flow path groove 36r is a linear flow path groove or a wavy flow path groove.

A fuel gas flow path 38 that communicates with the fuel gas inlet communication hole 34a and the fuel gas outlet communication hole 34b is provided on the surface 14a of the first separator 14 toward the framed MEA 10. Specifically, the fuel gas flow path 38 is formed between the first separator 14 and the framed MEA 10. The fuel gas flow path 38 has a plurality of flow path grooves 38r extending in the direction of arrow B. The flow path groove 38r is a linear flow path groove or a wavy flow path groove.

Between the surface 14b of the first separator 14 and the surface 16b of the second separator 16 adjacent to each other, a cooling medium flow path 40 communicating with the cooling medium inlet communication hole 32a and the cooling medium outlet communication hole 32b is indicated by an arrow B. It is formed so as to extend in the direction.

As shown in FIG. 2, a plurality of convex portions 39 forming the fuel gas flow path 38 are provided on the surface 14a (the surface facing the framed MEA 10) of the first separator 14. The convex portion 39 bulges toward the anode electrode 20 side and abuts on the anode electrode 20. The plurality of convex portions 39 extend along the flow path direction of the fuel gas flow path 38, and are formed at intervals in the flow path width direction (arrow C direction) of the fuel gas flow path 38. A plurality of flow path grooves 38r are formed between the plurality of convex portions 39.

A plurality of convex portions 37 forming the oxidizing agent gas flow path 36 are provided on the surface 16a (the surface facing the framed MEA 10) of the second separator 16. The convex portion 37 bulges toward the cathode electrode 22 side and abuts on the cathode electrode 22. The plurality of convex portions 37 extend along the flow path direction of the oxidant gas flow path 36, and are formed at intervals in the flow path width direction (arrow C direction) of the oxidant gas flow path 36. A plurality of flow path grooves 36r are formed between the plurality of convex portions 37. MEA10a is sandwiched between the protrusions 37 and 39.

The surface 14a of the first separator 14 is provided with a first seal line 42 (metal bead seal) that orbits the outer peripheral portion of the first separator 14 in order to prevent the fuel gas from leaking to the outside. The first seal line 42 bulges toward the frame member 24 and comes into airtight and liquidtight contact with the first frame-shaped sheet 24a (the region overlapping the second frame-shaped sheet 24b). The first seal line 42 has an outer bead portion 42a and an inner bead portion 42b provided inside the outer bead portion 42a. The outer peripheral end 20e of the anode electrode 20 is located between the outermost convex portion 39e in the flow path width direction of the plurality of convex portions 39 and the first seal line 42 (inner bead portion 42b). .. The first seal line 42 may be composed of only one of the outer bead portion 42a and the inner bead portion 42b.

The inner bead portion 42b goes around the fuel gas flow path 38, the fuel gas inlet communication hole 34a, and the fuel gas outlet communication hole 34b, and communicates them. The cross-sectional shape of each bead portion 42a, 42b is tapered toward the tip side (frame member 24 side). The tips of the bead portions 42a and 42b have a flat shape (may be a curved shape).

The flow path 38a formed between the first separator 14 and the frame member 24 on the inner side (MEA10a side) of the first seal line 42 communicates with the fuel gas flow path 38. Therefore, the fuel gas is supplied to the flow path 38a.

A second seal line 44 (metal bead seal) that goes around the outer peripheral portion of the second separator 16 is provided on the surface 16a of the second separator 16 in order to prevent the oxidant gas from leaking to the outside. The second seal line 44 bulges toward the frame member 24 and comes into airtight and liquidtight contact with the second frame-shaped sheet 24b. The first seal line 42 and the second seal line 44 face each other via the frame member 24. The frame member 24 is sandwiched between the first seal line 42 and the second seal line 44. The second seal line 44 has an outer bead portion 44a and an inner bead portion 44b provided inside the outer bead portion 44a.

The inner bead portion 44b goes around the oxidant gas flow path 36, the oxidant gas inlet communication hole 30a, and the oxidant gas outlet communication hole 30b, and communicates them. The cross-sectional shape of each bead portion 44a, 44b is tapered toward the tip side (frame member 24 side). The tips of the bead portions 44a and 44b have a flat shape (may be a curved shape). The outer peripheral end 22e of the cathode electrode 22 is located between the outermost convex portion 37e in the flow path width direction of the plurality of convex portions 37 and the second seal line 44 (inner bead portion 44b). ..

The flow path 36a formed between the second separator 16 and the frame member 24 on the inner side (MEA10a side) of the second seal line 44 communicates with the oxidant gas flow path 36. Therefore, the oxidant gas is supplied to the flow path 36a.

In FIG. 3, the fuel cell system 11 includes the fuel cell stack 11a described above, an oxidant gas supply device 50 that supplies the oxidant gas to the fuel cell stack 11a, and a fuel gas supply that supplies the fuel gas to the fuel cell stack 11a. A device 52 and a cooling medium supply device 54 that supplies a cooling medium to the fuel cell stack 11a are provided.

The oxidant gas supply device 50 includes an oxidant gas supply pipe 64a that communicates with the oxidant gas inlet communication hole 30a (see FIG. 1) via an oxidizer gas supply manifold 58a provided in the fuel cell stack 11a, and a fuel cell. It has an oxidant gas discharge pipe 64b that communicates with an oxidant gas outlet communication hole 30b (see FIG. 1) via an oxidant gas discharge manifold 58b provided on the stack 11a. An air pump 66 is arranged in the oxidant gas supply pipe 64a. A pressure adjusting valve 68 is provided in the oxidant gas discharge pipe 64b.

A humidifier 67 is provided in the oxidant gas supply pipe 64a and the oxidant gas discharge pipe 64b. The humidifier 67 is not particularly limited in structure as long as it can humidify the supplied air. In the oxidant gas supply pipe 64a, the air pump 66 is arranged on the upstream side of the humidifier 67. In the oxidant gas discharge pipe 64b, a pressure regulating valve 68 is arranged on the downstream side of the humidifier 67. The control unit 70 of the fuel cell system 11 controls, for example, at least one of the operating speed of the air pump 66 and the valve opening degree of the pressure regulating valve 68 to control the pressure of the oxidant gas flowing through the oxidant gas flow path 36. Control.

The fuel gas supply device 52 is provided in the fuel gas supply pipe 72a and the fuel cell stack 11a that communicate with the fuel gas inlet communication hole 34a (see FIG. 1) via the fuel gas supply manifold 60a provided in the fuel cell stack 11a. It has a fuel gas discharge pipe 72b that communicates with a fuel gas outlet communication hole 34b (see FIG. 1) via the fuel gas discharge manifold 60b.

A hydrogen tank 74 for storing high-pressure hydrogen is arranged upstream of the fuel gas supply pipe 72a. In the fuel gas supply pipe 72a, a sealing valve 76, a pressure adjusting valve 77, and an ejector 78 are arranged between the fuel gas supply manifold 60a and the hydrogen tank 74. A hydrogen circulation path 80 is connected to the ejector 78 and the fuel gas discharge pipe 72b. A hydrogen pump 82 for hydrogen circulation is arranged in the hydrogen circulation path 80. The control unit 70 controls the flow rate of the fuel gas flowing through the fuel gas flow path 38 by controlling the driving speed of the hydrogen pump 82.

The cooling medium supply device 54 includes a cooling medium circulation path 84 that circulates and supplies the cooling medium to the fuel cell stack 11a. The cooling medium circulation path 84 communicates with the cooling medium inlet communication hole 32a (see FIG. 1) via the cooling medium supply manifold 62a provided in the fuel cell stack 11a, and also communicates with the cooling medium outlet through the cooling medium discharge manifold 62b. It communicates with the communication hole 32b (see FIG. 1). A radiator 86 and a cooling pump 88 are arranged in the cooling medium circulation path 84.

The operation of the fuel cell system 11 including the power generation cell 12 (fuel cell stack 11a) configured as described above will be described below in relation to the operation method of the fuel cell according to the present embodiment.

As shown in FIG. 3, in the oxidant gas supply device 50, air is sent to the oxidant gas supply pipe 64a under the driving action of the air pump 66. After being humidified through the humidifier 67, this air is supplied to the oxidant gas inlet communication hole 30a (see FIG. 1) via the oxidant gas supply manifold 58a. The humidifier 67 adds the moisture and heat discharged from the oxidant gas discharge manifold 58b to the supplied air. On the other hand, in the fuel gas supply device 52, the fuel gas is supplied from the hydrogen tank 74 to the fuel gas supply pipe 72a under the opening action of the sealing valve 76. This fuel gas is supplied to the fuel gas inlet communication hole 34a (see FIG. 1) via the fuel gas supply manifold 60a. Further, in the cooling medium supply device 54, the cooling medium is supplied from the cooling medium circulation path 84 to the cooling medium inlet communication hole 32a (see FIG. 1) under the action of the cooling pump 88.

Therefore, as shown in FIG. 1, an oxidant gas such as an oxygen-containing gas is supplied to the oxidant gas inlet communication hole 30a, and a fuel gas such as a hydrogen-containing gas is supplied to the fuel gas inlet communication hole 34a. Be supplied. Further, a cooling medium such as pure water, ethylene glycol, or oil is supplied to the cooling medium inlet communication hole 32a.

Therefore, the oxidant gas is introduced into the oxidant gas flow path 36 of the second separator 16 from the oxidant gas inlet communication hole 30a, moves in the direction of arrow B, and is supplied to the cathode electrode 22 of the MEA 10a. On the other hand, the fuel gas is introduced from the fuel gas inlet communication hole 34a into the fuel gas flow path 38 of the first separator 14. The fuel gas moves in the direction of arrow B along the fuel gas flow path 38 and is supplied to the anode electrode 20 of the MEA 10a.

Therefore, in the MEA 10a, the oxidant gas supplied to the cathode electrode 22 and the fuel gas supplied to the anode electrode 20 are consumed by the electrochemical reaction in the second electrode catalyst layer 22a and the first electrode catalyst layer 20a. And power is generated.

In this case, the pressure of the first reaction gas (fuel gas) supplied to the fuel gas flow path 38 is set higher than the pressure of the second reaction gas (oxidizer gas) supplied to the oxidant gas flow path 36. To. Therefore, in FIG. 2, the flow path 38a formed between the first separator 14 and the frame member 24 allows the first reaction gas set at a pressure higher than that of the second reaction gas to flow. Therefore, in the frame member 24 arranged between the flow path 36a and the flow path 38a, the first frame-shaped sheet 24a side to the second frame-shaped sheet 24b side (that is, the first separator 14 side to the second separator) The differential pressure P acts toward (16 side). The differential pressure P is, for example, 5 to 300 kPa, preferably 10 to 200 kpa.

Next, in FIG. 1, the oxidant gas supplied to and consumed by the cathode electrode 22 is discharged in the direction of arrow A along the oxidant gas outlet communication hole 30b. Similarly, the fuel gas supplied to and consumed by the anode electrode 20 is discharged in the direction of arrow A along the fuel gas outlet communication hole 34b.

Further, the cooling medium supplied to the cooling medium inlet communication hole 32a is introduced into the cooling medium flow path 40 between the first separator 14 and the second separator 16 and then circulates in the direction of arrow B. After cooling the MEA10a, this cooling medium is discharged from the cooling medium outlet communication hole 32b.

In this case, in the present embodiment, as shown in FIG. 2, the frame member 24 is thicker than the first frame-shaped sheet 24a in which the inner peripheral portion 24an is joined to the outer peripheral portion of the MEA 10a and the first frame-shaped sheet 24a. It has a second frame-shaped sheet 24b, and the first frame-shaped sheet 24a and the second frame-shaped sheet 24b are joined to each other in the thickness direction. The inner peripheral portion 24an of the first frame-shaped sheet 24a is arranged between the outer peripheral portion 20c of the anode electrode 20 and the outer peripheral portion 22c of the cathode electrode 22, and the inner peripheral end 24be of the second frame-shaped sheet 24b is a gap G. Is arranged outside the outer peripheral end 22e of the cathode electrode 22. Then, between the frame member 24 and the first separator 14, the first reaction gas (fuel gas in the present embodiment) is set to a pressure higher than the pressure of the second reaction gas (oxidant gas in the present embodiment). ) Is provided, while a flow path 36a for passing the second reaction gas is provided between the frame member 24 and the second separator 16.

As described above, in the power generation cell 12, the gap G is provided on the side where the pressure of the reaction gas is low. That is, the second frame-shaped sheet 24b is arranged on the side where the pressure of the reaction gas is low. Therefore, the differential pressure P between the reaction gases increases from the first frame-shaped sheet 24a side (the side where the gap G is not formed) to the second frame-shaped sheet 24b side (the side where the gap G is formed). It works. The differential pressure P does not act on the joint surface (bonding surface) between the first frame-shaped sheet 24a and the second frame-shaped sheet 24b. Therefore, it is possible to prevent the first frame-shaped sheet 24a and the second frame-shaped sheet 24b from being peeled off due to the differential pressure P between the reaction gases.

On the other hand, unlike the present embodiment, when the gap G is provided on the side where the pressure of the reaction gas is high (the second frame-shaped sheet 24b is arranged), the gap G is formed from the side where the gap G is formed. The differential pressure between the reaction gases acts toward the non-reactive side. The differential pressure acts in a direction in which the first frame-shaped sheet 24a is separated from the second frame-shaped sheet 24b, particularly at the inner peripheral end 24be of the second frame-shaped sheet 24b. Therefore, peeling of the first frame-shaped sheet 24a and the second frame-shaped sheet 24b is caused.

On the other hand, in the present embodiment, as described above, since the gap G is provided on the side where the pressure of the reaction gas is low, the differential pressure P is such that the first frame-shaped sheet 24a is on the second frame-shaped sheet 24b side. Since it acts in the direction of pressing against, the peeling of the first frame-shaped sheet 24a and the second frame-shaped sheet 24b is prevented.

Further, in the present embodiment, in the first electrode and the second electrode (anode electrode 20 and cathode electrode 22), one electrode (anode electrode 20) is a region 21b overlapping the electrolyte membrane 18 and the first frame-shaped sheet 24a. An inclined region 21c inclined with respect to the electrolyte membrane 18 is provided between the region 21a overlapping the inner peripheral portion 24an. The other electrode (cathode electrode 22) is formed flat from the region 23b overlapping the electrolyte membrane 18 to the region 23a overlapping the inner peripheral portion 24an of the first frame-shaped sheet 24a. The outer peripheral portion 18c of the electrolyte membrane 18 is arranged between the other electrode (cathode electrode 22) and the inner peripheral portion 24an of the first frame-shaped sheet 24a. With this configuration, since no step is formed on the electrolyte membrane 18, it is possible to prevent the electrolyte membrane 18 from being damaged during manufacturing.

Further, in the present embodiment, the adhesive layer 24c is provided on the entire surface of the first frame-shaped sheet 24a on the second frame-shaped sheet 24b side. Therefore, the inner peripheral portion of the frame member 24 (inner peripheral portion 24an of the first frame-shaped sheet 24a) and the outer peripheral portion of the MEA 10a can be satisfactorily joined. Further, it is easy to provide the adhesive layer 24c on the first frame-shaped sheet 24a, and masking or the like is unnecessary.

The anode electrode 20 is set to be larger than the plane dimension of the cathode electrode 22, and the position of the outer peripheral end 18e of the electrolyte film 18 is the same as the outer peripheral end 22e of the cathode electrode 22. As a result, it is possible to prevent the electrolyte membrane 18 from being damaged by the differential pressure acting on the portion of the electrolyte membrane 18 corresponding to the outer peripheral end 22e of the cathode electrode 22.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention.

10 ... MEA with frame 10a ... MEA
12 ... Power generation cell 14 ... First separator 16 ... Second separator 18 ... Electrolyte film 20 ... Anode electrode 22 ... Cathode electrode 24 ... Frame member 24a ... First frame-shaped sheet 24b ... Second frame-shaped sheet 24c ... Adhesive layer

Claims (14)

An electrolyte membrane / electrode structure in which a first electrode and a second electrode are provided on both sides of the electrolyte membrane, a first separator laminated on the first electrode side of the electrolyte membrane / electrode structure, and the electrolyte membrane. A fuel cell provided with a second separator laminated on the second electrode side of the electrode structure, the first reaction gas is supplied to the first electrode, and the second reaction gas is supplied to the second electrode. There,
A frame member that orbits the outer peripheral portion is provided on the outer peripheral portion of the electrolyte membrane / electrode structure.
The frame member has a first frame-shaped sheet whose inner peripheral portion is joined to the outer peripheral portion of the electrolyte membrane / electrode structure, and a second frame-shaped sheet which is thicker than the first frame-shaped sheet. The 1-frame-shaped sheet and the 2nd frame-shaped sheet are joined to each other in the thickness direction.
The frame member is sandwiched between the first separator and the second separator, and the frame member is sandwiched between the first separator and the second separator.
The inner peripheral portion of the first frame-shaped sheet is arranged between the outer peripheral portion of the first electrode and the outer peripheral portion of the second electrode.
The inner peripheral end of the second frame-like sheet through the outer peripheral edge and the gap of the second electrode is disposed outward from the outer peripheral edge of the second electrode,
Between the frame member and the first separator, a flow path for passing the first reaction gas set to a pressure higher than the pressure of the second reaction gas is provided.
A flow path for passing the second reaction gas is provided between the frame member and the second separator.
A fuel cell characterized by that.
In the fuel cell according to claim 1,
The flow path between the frame member and the first separator allows fuel gas to flow as the first reaction gas.
The flow path between the frame member and the second separator allows an oxidant gas to flow as the second reaction gas.
A fuel cell characterized by that. In the fuel cell according to claim 1 or 2.
In the first electrode and the second electrode, the planar dimension of one electrode is set to be larger than the planar dimension of the other electrode.
A fuel cell characterized by that. In the fuel cell according to claim 3,
The first electrode is set to be larger than the plane dimension of the second electrode.
A fuel cell characterized by that. In the fuel cell according to claim 3 or 4.
The position of the outer peripheral edge of the electrolyte membrane is the same as the outer peripheral edge of the other electrode.
A fuel cell characterized by that. In the fuel cell according to any one of claims 1 to 5.
The inner peripheral portion of the first frame-shaped sheet is arranged between the electrolyte membrane and the first electrode.
A fuel cell characterized by that. In the fuel cell according to any one of claims 1 to 6.
In the first electrode and the second electrode, one of the electrodes is an inclined region inclined with respect to the electrolyte membrane between a region overlapping the electrolyte membrane and a region overlapping the inner peripheral portion of the first frame-shaped sheet. The other electrode is formed flat from the region overlapping the electrolyte membrane to the region overlapping the inner peripheral portion of the first frame-shaped sheet.
The outer peripheral portion of the electrolyte membrane is arranged between the other electrode and the inner peripheral portion of the first frame-shaped sheet.
A fuel cell characterized by that. In the fuel cell according to any one of claims 1 to 7.
An adhesive layer is provided over the entire surface of the surface of the first frame-shaped sheet on the side of the second frame-shaped sheet.
A fuel cell characterized by that. In the fuel cell according to claim 1,
The first separator is provided with a bead seal that bulges toward the frame member side in order to prevent leakage of the first reaction gas.
The second separator is provided with a bead seal that bulges toward the frame member side in order to prevent leakage of the second reaction gas.
The frame member is sandwiched between the bead seal provided on the first separator and the bead seal provided on the second separator.
A fuel cell characterized by that. An electrolyte membrane / electrode structure in which a first electrode and a second electrode are provided on both sides of the electrolyte membrane, a first separator laminated on the first electrode side of the electrolyte membrane / electrode structure, and the electrolyte membrane. A fuel cell having a second separator laminated on the second electrode side of the electrode structure, the first reaction gas being supplied to the first electrode, and the second reaction gas being supplied to the second electrode. It ’s a driving method,
A frame member that orbits the outer peripheral portion is provided on the outer peripheral portion of the electrolyte membrane / electrode structure.
The frame member has a first frame-shaped sheet in which an inner peripheral portion is joined to an outer peripheral portion of the electrolyte membrane / electrode structure, and a second frame-shaped sheet thicker than the first frame-shaped sheet. The 1-frame-shaped sheet and the 2nd frame-shaped sheet are joined to each other in the thickness direction.
The frame member is sandwiched between the first separator and the second separator, and the frame member is sandwiched between the first separator and the second separator.
The inner peripheral portion of the first frame-shaped sheet is arranged between the outer peripheral portion of the first electrode and the outer peripheral portion of the second electrode.
The inner peripheral end of the second frame-like sheet through the outer peripheral edge and the gap of the second electrode is disposed outward from the outer peripheral edge of the second electrode,
The first reaction gas having a pressure higher than the pressure of the second reaction gas is supplied to the flow path formed between the frame member and the first separator.
The second reaction gas is supplied to the flow path formed between the frame member and the second separator.
A method of operating a fuel cell, which is characterized by the fact that. In the method for operating a fuel cell according to claim 10,
A fuel gas is circulated as the first reaction gas in the flow path between the frame member and the first separator.
An oxidant gas is circulated as the second reaction gas in the flow path between the frame member and the second separator.
A method of operating a fuel cell, which is characterized by the fact that. In the method for operating a fuel cell according to claim 10 or 11.
The first electrode is set to be larger than the plane dimension of the second electrode.
The position of the outer peripheral edge of the electrolyte membrane is the same as the outer peripheral edge of the second electrode.
A method of operating a fuel cell, which is characterized by the fact that. The method for operating a fuel cell according to any one of claims 10 to 12.
The first separator includes a first reaction gas flow path for flowing the first reaction gas along the electrode surface of the electrolyte membrane / electrode structure, and the first reaction gas to prevent leakage of the first reaction gas. A bead seal that surrounds the reaction gas flow path and bulges toward the frame member is formed.
The first reaction gas flow path has a plurality of flow path grooves formed between a plurality of convex portions protruding toward the electrolyte membrane / electrode structure side, and the plurality of convex portions are the first reaction gas flow. Formed at intervals in the width direction of the flow path of the road,
The outer peripheral end of the first electrode is located between the outermost convex portion in the flow path width direction of the plurality of convex portions and the bead seal.
A method of operating a fuel cell, which is characterized by the fact that. The method for operating a fuel cell according to any one of claims 10 to 12.
The second separator includes a second reaction gas flow path for flowing the second reaction gas along the electrode surface of the electrolyte membrane / electrode structure, and the second reaction gas to prevent leakage of the second reaction gas. A bead seal that surrounds the reaction gas flow path and bulges toward the frame member is formed.
The second reaction gas flow path has a plurality of flow path grooves formed between the plurality of protrusions protruding toward the electrolyte membrane / electrode structure side, and the plurality of protrusions are the second reaction gas flow. Formed at intervals in the width direction of the flow path of the road,
The outer peripheral end of the second electrode is located between the outermost convex portion in the flow path width direction of the plurality of convex portions and the bead seal.
A method of operating a fuel cell, which is characterized by the fact that.

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