JP2004087505A - Solid polymer fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact solid polymer fuel cell capable of largely being improved in its service life. <P>SOLUTION: This solid polymer fuel cell has a unit cell that comprises a polymer electrolytic film; a fuel pole and an oxidant pole placed to hold the polymer electrolytic film; a fuel pole side current collector having a fuel supply channel for supplying fuel gas to the fuel pole; and an oxidizing pole side current collector having an oxidant supply channel for supplying oxidant gas to the oxidant pole. Reinforcing sheets are held between the fuel pole and a polymer electrolytic film, and between the oxidant pole and the polymer electrolytic film. Edges of areas of the fuel electrode pole and oxidant pole contacting to the polymer electrolytic film sandwich the electrolytic film but do not overlap with each other. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a polymer electrolyte fuel cell using, as an electrolyte, a polymer film having hydrogen ion conductivity or a composite material of an inorganic or organic material powder having hydrogen ion conductivity and a polymer material as a binder.

In recent years, fuel cells have attracted attention as high-efficiency energy conversion devices. Depending on the type of electrolyte used, fuel cells are broadly classified into low-temperature operating fuel cells such as alkaline type, solid polymer type and phosphoric acid type, and high-temperature operating fuel cells such as molten carbonate type and solid oxide type. You.

Among these, polymer electrolyte fuel cells (PEFCs), which use a polymer electrolyte membrane having ion conductivity as the electrolyte, have a compact structure, high power density, and can be operated with a simple system. , For space, remote islands, land, and vehicles.

Known polymer electrolyte membranes include polystyrene-based cation exchange membranes having sulfonic acid groups, mixed substances of fluorocarbon sulfonic acid and polyvinylidene fluoride, and those obtained by adding trifluoroethylene to a fluorocarbon matrix by grafting. ing. Recently, a perfluorocarbon sulfonic acid membrane (for example, Nafion: trade name, manufactured by DuPont) or the like has been used.

固体 A polymer electrolyte fuel cell using such a polymer electrolyte membrane as an electrolyte is usually configured as a stacked structure in which a plurality of unit cells 1 formed as shown in FIG. 17 are stacked.

The unit cell 1 includes a polymer electrolyte membrane 10 and a fuel electrode 11 and an oxidizer electrode 12 which are formed of a porous body carrying a catalyst such as platinum and arranged so as to sandwich the polymer electrolyte membrane 10 therebetween. A fuel electrode-side current collector 13 made of a porous material and disposed in contact with the back surface of the fuel electrode 11; an oxidant electrode-side current collector 14 disposed in contact with the back surface of the oxidant electrode 12; A plurality of fuel supply grooves 15 formed on a surface of the electric body 13 which is in contact with the fuel electrode 11 to supply and distribute fuel gas to the fuel electrode 11, and a surface of the oxidant electrode side current collector 14 which is in contact with the oxidant electrode 12. A plurality of oxidant supply grooves 16 formed to distribute and supply oxidant gas to the oxidant electrode 12, a cooling plate 17 provided on the back side of the fuel electrode side current collector 13, and provided on the cooling plate 17. Cooling water guide groove 18 for guiding cooling water The portion of the water is constituted by the humidifying water transmission plate 19 for controlling the amount of shift to the fuel electrode side current collector 13.

In FIG. 17, reference numerals 20 and 21 denote a fuel electrode and an oxidant gas surrounding the membrane electrode assembly composed of the polymer electrolyte membrane 10, the fuel electrode 11, and the oxidant electrode 12, while preventing leakage of the fuel gas and the oxidant gas. A frame spacer for ensuring insulation between the side current collector 13 and the oxidant electrode side current collector 14 is shown. When the cooling plate 17 is not interposed, the fuel electrode side current collector 13 and the oxidant electrode side current collector 14 may be integrated.

The polymer electrolyte membrane 10, the fuel electrode 11, and the oxidant electrode 12 are formed in a sheet shape, and their thickness is set to 1 mm or less to reduce internal resistance. Further, the polymer electrolyte membrane 10, the fuel electrode 11, and the oxidizer electrode 12 are often formed in a square shape in consideration of productivity. The area is determined by a current value required for power generation and a current value per unit area, that is, a current density, and is generally set to 100 cm ² or more, that is, 10 cm or more on one side.

The fuel electrode side current collector 13 and the oxidant electrode side current collector 14 are formed in the shape of the polymer electrolyte membrane 10 and each of the electrodes 11 and 12 as representatively shown in FIG. Many are formed in a square shape. A square area is set in the center according to the shape of each of the poles 11 and 12, and a plurality of fuel gas supply grooves 15 (oxidant gas supply grooves 16) are provided in parallel with this square area. Similarly, the cooling plate 17 has a square area in the center according to the shape of the poles 11 and 12, and a plurality of cooling water guide grooves 18 are provided in parallel with the square area.

Both ends of the fuel gas supply groove 15 are connected to fuel gas supply manifolds 24 provided in the stacking direction at the peripheral edge of the stacking element via communication passages 22 and 23 formed at substantially the same depth as the fuel gas supply groove 15. And a fuel gas discharge manifold 25. Similarly, both ends of the oxidizing gas supply groove 16 communicate with an oxidizing gas supply manifold 26 and an oxidizing gas discharge manifold 27, and both ends of the cooling water guide groove 18 are connected to a cooling water supply manifold 28 and a cooling water discharge manifold. It leads to 29. On the other hand, the humidified water permeable plate 19 is formed of a conductive porous thin plate obtained by sintering a metal powder or a hydrophilic carbon powder.

単 位 Since the electromotive force of the unit cell 1 configured as described above is as small as 1 V or less, a plurality of unit cells are stacked and connected in series to obtain a required electromotive force.

However, the conventional polymer electrolyte fuel cell configured as described above has the following problems.

That is, when a fuel gas containing hydrogen is supplied to the fuel electrode 11 and an oxidizing gas containing oxygen is supplied to the oxidizing electrode 12, the battery reaction is performed. As a by-product of the battery reaction, water is supplied to the oxidizing electrode 12 side. Occurs. This water is called product water. If a large amount of the generated water is present, supply of the oxidizing gas is hindered. Therefore, it is necessary to promptly remove generated water to the outside. The generated water easily moves to the oxidizing gas supply groove 16. For this reason, a method is generally adopted in which an oxidizing gas is excessively supplied and discharged by an unreacted oxidizing gas. In this method, the flow rate of the oxidizing gas and the flow rate of the excess oxidizing gas are important parameters. That is, the higher the flow rate, the more the generated water can be discharged.

However, in the conventional polymer electrolyte fuel cell, a square area is set in the center of the oxidant electrode side current collector 14 formed in a square, and a plurality of oxidant gas supply grooves 16 are formed in the square area in parallel. Therefore, it is difficult to increase the flow rate of the oxidizing gas, and it is difficult to extend the life of the battery.

The flow rate of the oxidizing gas can be increased by reducing the cross-sectional area of each of the oxidizing gas supply grooves 16, that is, the depth and width of the grooves. Is difficult to realize.

In the conventional polymer electrolyte fuel cell, the fuel electrode 11 and the oxidant electrode 12 are formed to have the same dimensions and the same area. Therefore, the edge portion of the region of the fuel electrode 11 in contact with the polymer electrolyte membrane 10 and the edge portion of the region of the oxidant electrode 12 in contact with the polymer electrolyte film 10 overlap with the polymer electrolyte membrane 10 interposed therebetween. When the membrane electrode assembly including the polymer electrolyte membrane 10, the fuel electrode 11, and the oxidant electrode 12 is press-molded, pressure concentrates on an edge portion and is in contact with the edge portion of the polymer electrolyte membrane 10. There was a possibility that the portion was pushed from both sides and damaged. Further, the portion of the polymer electrolyte membrane 10 sandwiched between the both edge portions is always in a state of being subjected to mechanical stress due to the tightening of the cell during power generation. There is also a possibility that the portion between the two edge portions of 10 deteriorates and is damaged.

(4) In the conventional polymer electrolyte fuel cell, a humidified water permeable plate 19 obtained by sintering metal powder or carbon powder is used. In such a sintered body, the porous structure is likely to differ depending on the sintering conditions. Further, it is difficult to control the uniform pore size and pore volume during sintering. For this reason, even in the same humidified water permeable plate 19, the hole diameter and the pore volume of each part vary, and further, the hole diameter and the pore volume of each humidified water permeable plate 19 vary. Due to such variations, the humidification water supplied to the polymer electrolyte membrane 10 becomes non-uniform, and the battery performance becomes unstable.

Furthermore, in order to make the cell compact, it is necessary to have a thin and mechanically strong one. However, the conventional manufacturing method of sintering powder requires a thickness of about 1 mm. In addition, because it is a porous body made of metal or carbon, if it is made thin, its mechanical strength will be lost, and eventually a conventional humidified water permeable plate cannot be made thin and has high mechanical strength, and a compact cell is realized. I can't.

As described above, in the conventional polymer electrolyte fuel cell, it is difficult to quickly discharge generated water, and large mechanical stress is easily applied to the polymer electrolyte membrane. There is a problem that the life of the battery is short because it cannot be performed.

Accordingly, an object of the present invention is to provide a compact polymer electrolyte fuel cell which can significantly improve the life and is compact.

た め In order to achieve the above object, a polymer electrolyte fuel cell is constructed by the following means.

The invention corresponding to claim 1 includes a polymer electrolyte membrane, a fuel electrode and an oxidant electrode arranged so as to sandwich the polymer electrolyte membrane, and a fuel supply groove for supplying a fuel gas to the fuel electrode. A fuel electrode side current collector, and a polymer electrolyte fuel cell comprising a unit cell comprising an oxidant electrode side current collector having an oxidant supply groove for supplying an oxidant gas to the oxidant electrode, A reinforcing sheet is attached between the fuel electrode and the polymer electrolyte membrane and between the oxidant electrode and the polymer electrolyte membrane, and an edge of a region where the fuel electrode and the oxidant electrode contact the polymer electrolyte membrane. The part is formed in a shape that does not polymerize with the polymer electrolyte membrane interposed therebetween.

According to a second aspect of the present invention, in the polymer electrolyte fuel cell according to the first aspect of the present invention, convex portions are formed in regions of the fuel electrode and the oxidant electrode that are in contact with the polymer electrolyte membrane. A reinforcing sheet having a thickness substantially equal to the height of the convex portion is attached so as to surround the convex portion.

According to a third aspect of the present invention, in the polymer electrolyte fuel cell according to the first aspect of the present invention, the fuel electrode and the oxidant electrode have different areas in contact with the polymer electrolyte membrane.

According to a fourth aspect of the present invention, in the polymer electrolyte fuel cell according to the first aspect of the present invention, the reinforcing sheet has a frame shape.

According to the present invention, the life can be greatly improved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view of a solid polymer fuel cell according to an embodiment of the present invention, in which four solid polymer fuel cells 41 are connected in series to constitute a power source for an electric vehicle. It is shown.

As shown in FIG. 2, each of the polymer electrolyte fuel cells 41 has a plurality of unit cells 42 stacked, and conductive plates 43a and 43b, insulating plates 44a and 44b, and end plates 45a and 45b are provided at both ends of the stacked body. In this state, the end plates 45a and 45b are integrated by tightening using an insulating rod 46 between the four corner positions.

各 Each of the polymer electrolyte fuel cells 41 thus configured has a rectangular cross section orthogonal to the stacking direction. Then, the four polymer electrolyte fuel cells 41 are arranged side by side in a direction orthogonal to the direction in which the unit cells 42 are stacked, with the short sides thereof adjacent to each other in the cross section, and the conductive plates 43a, Boss bars 47 protruding from 43b are connected by lead wires 48 to electrically connect adjacent laminates in series. By arranging the polymer electrolyte fuel cell 41 in this manner, the total height of the space for installing the power source can be reduced, and the fuel cell can be installed in a low space such as under the floor of an automobile.

Each of the polymer electrolyte fuel cells 41 has a fuel gas supply manifold 49a and a fuel gas discharge manifold 49b for supplying and discharging fuel gas, oxidizing gas, and cooling water necessary for power generation, similarly to the conventional battery. A water supply manifold 50a, a drain manifold 50b, an oxidizing gas supply manifold 51a, and an oxidizing gas discharge manifold 51b are formed in the stacking direction. In this example, the corresponding manifolds of adjacent polymer electrolyte fuel cells 41 are connected in series. Of course, they can be supplied in parallel.

FIG. 3 is an exploded perspective view of the unit cell 42. The unit cell 42 includes a polymer electrolyte membrane 60 formed of a material similar to a known one. The polymer electrolyte membrane 60 has a thickness of, for example, about 0.18 mm, and has a smaller area on both sides than the polymer electrolyte membrane and a rectangle (for example, a short side) such that the short side is located on the side where the manifold is formed. The fuel electrode 61 and the oxidant electrode 62 formed in a size of 10 cm, a long side of 20 cm, and an electrode area of 200 cm ² are arranged in contact with each other. The fuel electrode 61 and the oxidizer electrode 62 are formed by coating a surface of a carbon porous body having a thickness of, for example, 0.4 mm with carbon particles containing platinum.

(6) On the fuel electrode 61, as shown in FIGS. 6 and 7, a convex portion 63 that defines a rectangular region (area) in contact with the polymer electrolyte membrane 60 is formed. Similarly, as shown in FIGS. 6 and 7, the oxidant electrode 62 is also formed with a convex portion 64 that defines a rectangular region that contacts the polymer electrolyte membrane 60. The area of the convex portion 64 is different from the area of the convex portion 63, and is set to be large here. That is, the edge portion A of the convex portion 63 and the edge portion B of the convex portion 64 have an area relationship such that they do not overlap in the stacking direction with the polymer electrolyte membrane 60 interposed therebetween. Specifically, the area relationship is such that the edge portion B is located 2 to 5 mm outside the edge portion A. Then, a fluororesin-based sheet or the same material as that of the polymer electrolyte membrane 60 having substantially the same thickness as the height of the convex portion 63 so as to surround the convex portion 63 formed on the fuel electrode 61, and having substantially the same thickness as the height of the convex portion 63. The frame-shaped reinforcing sheet 65 formed in the sheet shape is mounted. Similarly, a frame-shaped reinforcing sheet 65 formed in a similar sheet shape is mounted around the convex portion 64 formed on the oxidant electrode 62. Further, on the outer peripheral portions of the fuel electrode 61 and the oxidizer electrode 62, sealing materials 67 and 68 formed in a frame shape with an insulating sheet made of fluoro rubber or the like having substantially the same thickness as these outer peripheral portions are arranged. .

A fuel electrode side current collector plate 69 that has a function of supplying fuel gas to the fuel electrode 61 and a function of collecting power is in contact with the back side of the fuel electrode 61, that is, the lower surface side of the fuel electrode 61 in FIGS. Are located. The fuel electrode side current collector plate 69 is formed of a hydrophilic carbon porous plate. As shown in FIGS. 5 and 6, a fuel supply groove 70 for supplying a fuel gas to the fuel electrode 61 is formed in a contact surface of the fuel electrode side current collector plate 69 with the fuel electrode 61. A plurality of rectangular areas C having a smaller area are formed so as to extend in a direction along the long side of the fuel electrode 61. For example, 50 fuel supply grooves 70 are provided with a width of 1 mm, a depth of 0.5 mm, a length of 20 cm, and a pitch of 2 mm. Similarly, on the rear side of the oxidant electrode 62, that is, on the upper side in FIGS. 3 and 6 of the oxidant electrode 62, an oxidant that exhibits a function of supplying an oxidant gas to the oxidant electrode 62 and a function of collecting electricity. The pole-side current collector 71 is disposed in contact with the pole. The oxidant electrode side current collector 71 is formed of a dense carbon plate. As shown in FIGS. 4 and 6, an oxidant supply groove 72 for supplying an oxidant gas to the oxidant electrode 62 is provided in a contact surface of the oxidant electrode side current collector plate 71 with the oxidant electrode 62. A plurality of regions are formed in a rectangular region D smaller than the area of the oxidant electrode 62 so as to extend in a direction along the long side of the oxidant electrode 62. For example, 50 oxidant supply grooves 72 are provided at a pitch of 1 mm, a depth of 0.5 mm, a length of 20 cm, and a pitch of 2 mm. 4 shows the oxidant electrode-side current collector 71 as viewed from below in FIG.

A humidified water permeable plate 73 is disposed in contact with the lower surface side of the fuel electrode side current collector plate 69 in FIGS. 3 and 6, and a cooling plate 74 is provided on the lower surface side of the humidified water permeable plate 73 in FIGS. 3 and 6. Are arranged in contact. The humidified water permeable plate 73 is provided with a conductive non-sintered plate, for example, as shown in FIG. 8, several hundred pores 75 having a hole diameter of 10 μm in a region opposed to a region where the fuel gas supply groove 70 is provided. On both sides of a stainless steel thin plate 76, a thin plate 77 in which 30% of carbon is mixed in a porous fluororesin-based sheet having a pore diameter of 10 μm and a pore volume of 70% is arranged and integrated to have a thickness of 0.16 mm. ing.

The cooling plate 74 is formed of a dense carbon plate or a metal plate. On the surface of the cooling plate 74 located on the humidified water permeable plate 73 side, a guide groove 78 for guiding cooling water is provided in a region facing the region where the fuel gas supply groove 70 is provided, in parallel with the fuel gas supply groove 70. A plurality is formed.

Both short sides of the polymer electrolyte membrane 60, the frame-shaped reinforcing sheets 65 and 66, the sealing materials 67 and 68, the fuel electrode side current collector 69, the oxidant electrode side current collector 71, the humidified water transmission plate 73, and the cooling plate 74 Portions (on the short sides of the rectangular regions C and D and outside the rectangular regions), holes 80 and 81 constituting the fuel gas supply manifold 49a and the fuel gas discharge manifold 49b, the water supply manifold 50a and the drainage manifold 50b Are formed so as to communicate with each other in the stacking direction with the holes 84 and 85 forming the oxidizing gas supply manifold 51a and the oxidizing gas discharge manifold 51b.

The fuel gas supply groove 70 provided on the fuel electrode side current collector plate 69 communicates with holes 80 and 81 for supplying / discharging the fuel gas, and the oxidant supply hole provided on the oxidant electrode side current collector plate 71. The groove 72 communicates with holes 84 and 85 for supplying / discharging the oxidizing gas, and the guide groove 78 provided on the cooling plate 74 communicates with holes 82 and 83 for supplying / discharging the cooling water.

As described above, in the polymer electrolyte fuel cell 41 according to this example, the oxidizing agent extends along the longer side of the rectangle in the substantially rectangular region D of the surface of the oxidizing electrode side current collector 71 that contacts the oxidizing electrode 62. Since the plurality of oxidant supply grooves 72 for guiding the gas are provided, the flow rate of the oxidant gas can be increased without reducing the depth and width of each oxidant supply groove. The generated water generated in 62 can be satisfactorily removed.

That is, in this example, the oxidant electrode 62 has a short side of 10 cm, a long side of 20 cm, and an electrode area of 200 cm ² , and the oxidant supply groove 72 has a width of 1 mm, a depth of 0.5 mm, and a length of 0.5 mm. 50 pieces are provided at a pitch of 20 cm and 2 mm. Now, assuming that the current density is 0.4 A / cm ² , the air utilization rate is 40%, and the oxidant gas (air) supply pressure is 1 atm, the flow rate of the oxidant gas flowing through each oxidant supply groove 72 is 300 cm. / sec. On the other hand, a square electrode (side length 14 cm) having the same electrode area of 200 cm ² , an oxidant supply groove having the same groove width, groove depth, and arrangement pitch is provided, and oxidant gas is supplied under the same conditions. The flow rate of the oxidizing gas flowing through each oxidizing agent supply groove is 210 cm / sec. Thus, in this example, the flow rate of the oxidizing gas can be increased by a factor of 1.5 while maintaining the same electrode area. Therefore, the generated water can be discharged well. As a result, the generated water does not stay in the oxidant electrode 62 to hinder the supply of the oxidant gas, and the battery performance can be maintained for a long time.

The fact that the oxidant electrode 62 and the fuel electrode 61 can be formed in a rectangular shape in this way means that the planar shape of the unit cell 42 can also be formed in a rectangular shape, and that the cross-sectional area orthogonal to the stacking direction of the fuel cell stack is also formed in a rectangular shape. You can do it. That is, the fuel cell stack can be formed in a nearly flat shape with the required electrode area secured, so that it can be applied to objects having only a low installation space, such as electric vehicles. It becomes possible.

Further, in the above example, the fuel electrode 61 and the oxidizer electrode 62 are so formed that the edge portions A and B of the regions of the fuel electrode 61 and the oxidizer electrode 62 that come into contact with the polymer electrolyte membrane 60 do not polymerize with the polymer electrolyte membrane 60 interposed therebetween. 62 are formed. Therefore, the polymer electrolyte membrane 60 does not have a portion sandwiched between both edge portions A and B. For this reason, it is possible to prevent the polymer electrolyte membrane 60 from being damaged due to the presence of the above-described edge portions A and B when the cell is fastened during power generation, as well as when the membrane electrode assembly is pressed. .

FIG. 9 shows the results of a power generation test for comparing performance using the unit cell according to this example and the unit cell according to the related art. In the unit cell of the conventional example, the cell voltage dropped to 0.2 V in about 2000 hours, but in the unit cell according to this example, the cell voltage did not decrease even after more than 4000 hours.

Further, a power generation test was performed by a screen printer using a fuel electrode and an oxidizer electrode manufactured using a screen pattern in which the peripheral portion of the electrode was thinned by the thickness of the frame-shaped reinforcing sheets 65 and 66. A result equivalent to the characteristic shown in FIG. 9 was obtained.

Further, in the above example, the humidified water permeable plate 73 is formed of a conductive non-sintered member, a thin plate of a fluororesin material having a porous structure containing a conductive material, and a metal plate having pores. It is very easy to control the pore volume, and as a result, humidified water can be uniformly supplied to the polymer electrolyte membrane 60.

That is, FIG. 10 shows a power generation test result of a five-cell stacked battery in which five unit cells according to the above example are stacked, and FIG. 11 shows a conventional five-cell stacked battery in which five unit cells are stacked. The power generation test results are shown.

(4) In the conventional laminated battery using unit cells, the cell voltage varied from cell to cell immediately after the start of power generation, and the cell voltage remained variable even after 5000 hours, and further decreased by an average of 0.12 V. However, in the stacked battery using the unit cells according to the present example, the cell voltages were uniform immediately after the start of power generation, and there was no variation or decrease in the cell voltage even after 5000 hours. Further, as the humidifying water permeable plate 73, a 30% composite of a 100-mesh, fluororesin-based sheet having a mesh structure with a wire diameter of 85 μm and carbon 30%, and 10 μm pores formed by etching in the central 10 cm × 10 cm area. When the above-described power generation test was performed using 300 stainless steel sheets, the same results were obtained in both cases. These are due to the fact that humidified water could be uniformly supplied to the polymer electrolyte membrane 60.

The present invention is not limited to the above-described example, and can be variously modified.

That is, in the above example, the size of the fuel electrode 61 and the size of the oxidant electrode 62 are the same, but may be different as shown in FIG.

Further, as shown in FIG. 13, the area of the polymer electrolyte membrane 60 is made the same as the size of the fuel electrode 61 or the oxidant electrode 62, and a sealing material 91 formed in a frame shape with a fluororesin sheet or the like is provided on the outside thereof. It may be arranged. Further, as shown in FIG. 14, a configuration in which only the sizes of the fuel electrode 61 and the oxidant electrode 62 are changed.

Further, the configuration of the humidification water permeable plate is not limited to the above-described example. As shown in FIG. 15, a portion corresponding to the region where the cooling water guide groove of the cooling plate is provided has a mesh structure. A humidified water permeable plate 73a formed of a member 92 in which a base sheet and carbon are combined and formed around a member 93 such as a fluororesin sheet may be used.

Further, as shown in FIG. 16, it is also possible to use a humidification water permeable plate 73b formed of a stainless steel thin plate 94 and provided with pores 95 having different hole diameters in a portion of the thin plate 94 located on the cooling water guide groove. Good. In this example, the length of the cooling water guide groove is divided into three, 15 μm in the 1/3 region located upstream, 10 μm in the 1/3 region located in the middle stream, and 3 μm downstream. In one-third of the region, a 5 μm pore 95 is provided, and the diameter of the pore is reduced from upstream to downstream. By using the humidification water permeable plate 73b having such a configuration, it is possible to control the amount of humidification water supplied to the downstream portion where the amount of humidification tends to be excessive due to the generated water. The pores can be formed in the metal plate by etching, laser processing, electric discharge machining, drilling, or the like. Further, the thickness of the humidified water permeable plate is preferably 0.5 mm or less.

FIG. 1 is a perspective view showing an example of a mounting mode of a polymer electrolyte fuel cell according to an embodiment of the present invention. FIG. 2 is a side view of the polymer electrolyte fuel cell. FIG. 3 is an exploded perspective view of a unit cell incorporated in the polymer electrolyte fuel cell. The figure which shows one surface of the oxidant electrode side current collector incorporated in the unit cell. The figure which shows one surface of the fuel electrode side current collection plate built in the same unit cell. FIG. 4 is a longitudinal sectional view of the unit cell. FIG. 3 is an exploded cross-sectional view of a main part of the unit cell. FIG. 3 is an exploded perspective view of a humidified water permeable plate incorporated in the unit cell. The figure which shows the electric power generation characteristic of the same unit cell compared with the conventional example. The figure which shows the electric power generation characteristic of the same polymer electrolyte fuel cell. The figure which shows the electric power generation characteristic of the conventional polymer electrolyte fuel cell. The figure for explaining the modification of the present invention. The figure for explaining another modification of the present invention. FIG. 10 is a view for explaining still another modified example of the present invention. FIG. 9 is a view for explaining a different modification of the present invention. FIG. 9 is a diagram for explaining still another modified example of the present invention. FIG. 5 is a longitudinal sectional view of a unit cell incorporated in a conventional polymer electrolyte fuel cell. The figure which shows one surface of the fuel electrode side current collection plate incorporated in the same unit cell ... figure of this invention.

Explanation of reference numerals

41: solid polymer fuel cell, 42: unit cell, 49a: fuel gas supply manifold, 49b: fuel gas discharge manifold, 50a: water supply manifold, 50b: drain manifold, 51a: oxidant gas supply manifold, 51b: oxidant Gas discharge manifold, 60 ... Polymer electrolyte membrane, 61 ... Fuel electrode, 62 ... Oxidizer electrode, 63,64 ... Protrusion, 65,66 ... Frame-shaped reinforcing sheet, 67,68 ... Seal material, 69 ... Fuel electrode side Current collector plate, 70: fuel supply groove, 71: oxidant electrode side current collector plate, 72: oxidant supply groove, 73, 73a, 73b: humidified water permeable plate, 74: cooling plate, 78: guide groove, A, B: edge part, C, D: rectangular area

Claims (4)

A polymer electrolyte membrane, a fuel electrode and an oxidizer electrode arranged to sandwich the polymer electrolyte membrane, and a fuel electrode side current collector having a fuel supply groove for supplying a fuel gas to the fuel electrode; A polymer electrolyte fuel cell comprising a unit cell comprising an oxidant electrode-side current collector having an oxidant supply groove for supplying an oxidant gas to the oxidant electrode,
A reinforcing sheet is attached between the fuel electrode and the polymer electrolyte membrane and between the oxidant electrode and the polymer electrolyte membrane, and an edge of a region where the fuel electrode and the oxidant electrode contact the polymer electrolyte membrane. A polymer electrolyte fuel cell, wherein the portion is formed in a shape that does not polymerize across the polymer electrolyte membrane. Protrusions are respectively formed in regions of the fuel electrode and the oxidant electrode that are in contact with the polymer electrolyte membrane, and a reinforcing sheet formed to have a thickness substantially equal to the height of the protrusions so as to surround these protrusions. The polymer electrolyte fuel cell according to claim 1, wherein: The solid polymer fuel cell according to claim 1, wherein the fuel electrode and the oxidant electrode have different areas in contact with the polymer electrolyte membrane. The solid polymer fuel cell according to claim 1, wherein the reinforcing sheet has a frame shape.

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