JP2013098043A - Fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent excessive load on an outer peripheral end of an electrode catalyst layer when a fuel cell is fastened, and to reliably prevent damage to a solid polymer electrolyte membrane.SOLUTION: An electrolyte membrane/electrode structure 12 with protective films includes: an MEA 12a that has a cathode electrode 20, and an anode electrode 22, that sandwich a solid polymer electrolyte membrane 18 therebetween; and protective films 24a and 24b that are bonded to an outer peripheral end edge part of the solid polymer electrolyte membrane 18. The electrolyte membrane/electrode structure 12 with protective films has a power generation section 46 and an edge periphery section 48. On an outer peripheral edge thereof having contact with the MEA 12a, a cathode separator 14 has a depression 14c that houses the edge periphery section 48 including an outer peripheral end 20ae. On an outer peripheral edge thereof having contact with the MEA 12a, an anode separator 16 has a depression 16c that houses the edge periphery section 48 including an outer peripheral end 22ae.

Description

  The present invention provides an electrolyte membrane / electrode structure in which a first electrode and a second electrode each having an electrode catalyst layer and a gas diffusion layer are provided on both sides of a solid polymer electrolyte membrane, and the electrolyte membrane / electrode structure The present invention relates to a fuel cell including separators disposed on both sides.

  In general, a polymer electrolyte fuel cell employs a polymer electrolyte membrane made of a polymer ion exchange membrane. This fuel cell comprises an electrolyte membrane / electrode structure in which an anode electrode and a cathode electrode each comprising a catalyst layer (electrode catalyst layer) and a gas diffusion layer (porous carbon) are disposed on both sides of a solid polymer electrolyte membrane ( MEA) is sandwiched between separators (bipolar plates). This fuel cell is used as, for example, an in-vehicle fuel cell stack by stacking a predetermined number of fuel cells.

  In this type of electrolyte membrane / electrode structure, the outer peripheral end position of one catalyst layer and the outer peripheral end position of the other catalyst layer are shifted from each other with respect to the film thickness direction of the solid polymer electrolyte membrane. There is a case.

  For example, an electrolyte membrane-electrode assembly disclosed in Patent Document 1 includes a polymer electrolyte membrane 1 and a cathode catalyst layer 2 formed on one surface of the polymer electrolyte membrane 1 as shown in FIG. And an end portion of the cathode catalyst layer 2 so that the area of the anode catalyst layer 3 formed on the other surface of the polymer electrolyte membrane 1 and the area of the effective anode catalyst layer is larger than the area of the effective cathode catalyst layer. And a first gasket layer 4 formed on at least a part of the first gasket layer 4.

  A reinforcing layer 5 having a strength higher than that of the polymer electrolyte membrane 1 is provided at a portion overlapping the end portion of the cathode catalyst layer 2 in at least the thickness direction of the electrolyte membrane-electrode assembly of the polymer electrolyte membrane 1. Has been placed.

JP 2006-338938 A

  In Patent Document 1, a fuel cell is configured by sandwiching an electrolyte membrane-electrode assembly between separators, and a plurality of the fuel cells are stacked and used as a fuel cell stack. A predetermined tightening load is applied to the fuel cell stack in the stacking direction in order to ensure desired power generation performance and sealing performance.

  At that time, the outer peripheral end portion (edge portion) of the cathode catalyst layer 2 is pressed against the reinforcing layer 5, and the outer peripheral end portion (edge portion) of the anode catalyst layer 3 is against the reinforcing layer 5 and the polymer electrolyte membrane 1. It is pressed. For this reason, the reinforcing layer 5 and the polymer electrolyte membrane 1 have a problem that the surface pressure increases in the vicinity of each edge portion and the wall thickness is reduced, resulting in a decrease in durability.

  The present invention solves this type of problem, and when the fuel cell is tightened, an excessive load is not applied to the outer peripheral end of the electrode catalyst layer, and the solid polymer electrolyte membrane is reliably damaged. An object of the present invention is to provide a fuel cell that can be blocked.

  The present invention provides an electrolyte membrane / electrode structure in which a first electrode and a second electrode each having an electrode catalyst layer and a gas diffusion layer are provided on both sides of a solid polymer electrolyte membrane, and the electrolyte membrane / electrode structure The present invention relates to a fuel cell including separators disposed on both sides.

  The electrolyte membrane / electrode structure includes a power generation unit having a solid polymer electrolyte membrane sandwiched between the first electrode and the second electrode, and the outer peripheral ends of the electrode catalyst layers of the first electrode and the second electrode. The separator has an edge portion sandwiching the solid polymer electrolyte membrane, and the separator has a recess for accommodating the edge portion on the surface in contact with the electrolyte membrane / electrode structure.

  Further, in this fuel cell, the outer peripheral end portion of the electrode catalyst layer constituting the first electrode is set to a dimension projecting outward in the electrode surface direction from the outer peripheral end portion of the electrode catalyst layer constituting the second electrode. It is preferable.

  Furthermore, in this fuel cell, it is preferable that a protective film is provided on the outer periphery of the gas diffusion layer.

  Furthermore, in this fuel cell, it is preferable that a protective film is provided between the solid polymer electrolyte membrane and the gas diffusion layer.

  In the fuel cell, when the fuel cells are stacked, a gap is preferably formed between the electrolyte membrane / electrode structure and the separator outside the edge portion in the electrode surface direction.

  According to the present invention, the separator is formed with a recess corresponding to the edge portion of the electrolyte membrane / electrode structure. For this reason, when the fuel cell is tightened, the tightening allowance at the edge portion is set to be smaller than the tightening allowance at the power generation portion. Therefore, in the power generation unit, it is possible to secure a surface pressure necessary for ensuring the power generation performance, while it is possible to suppress an excessive tightening force from being applied to the outer peripheral end portion of the electrode catalyst layer at the edge portion. Thereby, while having desired electric power generation performance, it becomes possible to suppress the damage of the solid polymer electrolyte membrane in an edge part favorably.

It is a principal part disassembled perspective explanatory drawing of the fuel cell which concerns on the 1st Embodiment of this invention. FIG. 2 is a sectional view of the fuel cell taken along line II-II in FIG. 1. It is front explanatory drawing by the side of the anode electrode of the membrane-electrode structure with a protective film which comprises the said fuel cell. It is principal part cross-sectional explanatory drawing before the fastening of the said fuel cell. It is a relation explanatory view of cell thickness, power generation part surface pressure, and edge part surface pressure. It is a principal part disassembled perspective explanatory drawing of the fuel cell which concerns on the 2nd Embodiment of this invention. It is principal part cross-sectional explanatory drawing of the said fuel cell. It is principal part cross-sectional explanatory drawing before the fastening of the said fuel cell. It is principal part cross-sectional explanatory drawing of the fuel cell which concerns on the 3rd Embodiment of this invention. It is principal part cross-sectional explanatory drawing of the fuel cell which concerns on the 4th Embodiment of this invention. It is explanatory drawing of the membrane electrode assembly disclosed by patent document 1. FIG.

  As shown in FIGS. 1 and 2, a fuel cell 10 according to a first embodiment of the present invention sandwiches an electrolyte membrane / electrode structure 12 with a protective film and the electrolyte membrane / electrode structure 12 with a protective film. The cathode side separator 14 and the anode side separator 16 are provided.

  The cathode side separator 14 and the anode side separator 16 are comprised by a carbon separator, for example. In addition, the cathode side separator 14 and the anode side separator 16 may be configured by, for example, a metal thin plate instead of the carbon separator.

  As shown in FIG. 2, the electrolyte membrane / electrode structure 12 with a protective film includes an MEA 12a, and the MEA 12a includes, for example, a solid polymer electrolyte membrane 18 in which a thin film of perfluorosulfonic acid is impregnated with water; A cathode electrode (second electrode) 20 and an anode electrode (first electrode) 22 sandwiching the solid polymer electrolyte membrane 18 are included. The solid polymer electrolyte membrane 18 uses an HC (hydrocarbon) electrolyte in addition to a fluorine electrolyte.

  The cathode electrode 20 is disposed on one surface 18 a of the solid polymer electrolyte membrane 18, and the anode electrode 22 is disposed on the other surface 18 b of the solid polymer electrolyte membrane 18. The outer peripheral ends of the solid polymer electrolyte membrane 18 extend outward from the outer peripheral ends of the cathode electrode 20 and the anode electrode 22.

  The cathode electrode 20 is provided with an electrode catalyst layer 20a joined to the surface 18a of the solid polymer electrolyte membrane 18, and a gas diffusion layer 20b laminated on the electrode catalyst layer 20a. The anode electrode 22 is provided with an electrode catalyst layer 22a bonded to the surface 18b of the solid polymer electrolyte membrane 18, and a gas diffusion layer 22b laminated on the electrode catalyst layer 22a.

  The outer peripheral end portion 22ae of the electrode catalyst layer 22a that constitutes the anode electrode 22 is set to a dimension that protrudes outward in the electrode surface direction from the outer peripheral end portion 20ae of the electrode catalyst layer 20a that constitutes the cathode electrode 20. In contrast to the above configuration, the outer peripheral end portion 20ae of the cathode electrode 20 may be configured to protrude outward in the electrode surface direction from the outer peripheral end portion 22ae of the anode electrode 22.

  The electrode catalyst layers 20a and 22a form catalyst particles in which platinum particles are supported on carbon black, use a polymer electrolyte as an ion conductive binder, and uniformly mix the catalyst particles in a solution of the polymer electrolyte. The catalyst paste produced in this way is configured by printing, coating or transferring on both sides of the solid polymer electrolyte membrane 18. The gas diffusion layers 20b and 22b are made of carbon paper or the like and terminate outside the outer peripheral ends 20ae and 22ae of the electrode catalyst layers 20a and 22a.

  As shown in FIGS. 1 to 3, the electrolyte membrane / electrode structure 12 with a protective film is bonded to the outer peripheral edges of the surfaces 18 a and 18 b of the solid polymer electrolyte membrane 18 with an adhesive, and the cathode electrode 20. And protective films 24 a and 24 b made of a resin frame member joined to the tip of the anode electrode 22. The protective films 24a and 24b are made of, for example, PPS (polyphenylene sulfide), PPA (polyphthalamide), or the like, or may be made of an elastic polymer material.

  As shown in FIG. 2, the cathode side separator 14 is provided with a recess 14c that accommodates the periphery of the edge portion (described later) including the outer peripheral end portion 20ae (edge portion) at the outer peripheral edge portion in contact with the MEA 12a. The anode side separator 16 is provided with a recess 16c that accommodates the periphery of the edge portion (described later) including the outer peripheral end portion 22ae (edge portion) at the outer peripheral edge portion in contact with the MEA 12a.

  In a state where the fuel cells 10 are stacked (clamped), gaps S are formed between the protective films 24a and 24b and the surface 14a of the cathode side separator 14 and the surface 16b of the anode side separator 16, respectively. . This is to prevent the surface pressure from becoming higher than necessary by directly sandwiching the protective films 24a and 24b between the cathode side separator 14 and the anode side separator 16.

  As shown in FIG. 1, one end edge of the fuel cell 10 in the direction of arrow A (horizontal direction in FIG. 1) communicates with each other in the direction of arrow B, which is the stacking direction, and contains an oxidant gas, for example, oxygen An oxidant gas inlet communication hole 30a for supplying gas, a cooling medium inlet communication hole 32a for supplying a cooling medium, and a fuel gas outlet communication hole 34b for discharging a fuel gas, for example, a hydrogen-containing gas, Arranged in the direction of arrow C (vertical direction).

  The other end edge of the fuel cell 10 in the direction of arrow A communicates with each other in the direction of arrow B, and a fuel gas inlet communication hole 34a for supplying fuel gas, and a cooling medium outlet communication hole for discharging the cooling medium. 32b and an oxidant gas outlet communication hole 30b for discharging the oxidant gas 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 14a of the cathode separator 14 facing the electrolyte membrane / electrode structure 12 with the protective film. .

  A fuel gas flow path 38 communicating with the fuel gas inlet communication hole 34a and the fuel gas outlet communication hole 34b is formed on the surface 16a of the anode separator 16 facing the electrolyte membrane / electrode structure 12 with the protective film. Between the surface 14b of the cathode-side separator 14 and the surface 16b of the anode-side separator 16, a cooling medium flow path 40 that communicates with the cooling medium inlet communication hole 32a and the cooling medium outlet communication hole 32b is formed.

  A first seal member 42 is provided on the surfaces 14a and 14b of the cathode-side separator 14 so as to go around the outer peripheral end of the cathode-side separator 14, and the surfaces 16a and 16b of the anode-side separator 16 are provided with the anode A second seal member 44 is provided around the outer peripheral end of the side separator 16.

  The first and second sealing members 42 and 44 include, for example, EPDM, NBR, fluorine rubber, silicone rubber, fluorosilicone rubber, butyl rubber, natural rubber, styrene rubber, chloroprene or acrylic rubber, a cushioning material, Alternatively, a packing material is used.

  As shown in FIG. 2, the electrolyte membrane / electrode structure 12 with a protective film includes a power generation unit 46 in which the solid polymer electrolyte membrane 18 is sandwiched between the cathode electrode 20 and the anode electrode 22, and outer peripheries of the electrode catalyst layers 20 a and 22 a. And an edge portion periphery 48 covering a region including the end portions 20ae and 22ae. The edge portion periphery 48 corresponds to a range L in which the concave portion 14c of the cathode side separator 14 and the concave portion 16c of the anode side separator 16 are provided.

  In the fuel cell 10, when the fuel cells 10 are stacked, the interference margin around the edge portion 48 is set to be smaller than the interference margin in the power generation unit 46. Specifically, as shown in FIG. 4, before assembly of the fuel cell 10, the thickness Tam of the power generation unit 46 of the electrolyte membrane / electrode structure 12 with the protective film, and the thickness of the power generation unit 46 of the cathode separator 14. Tac, the thickness Taa of the power generation section 46 of the anode separator 16, the thickness Tbm of the edge portion periphery 48 of the electrolyte membrane / electrode structure 12 with the protective film, and the edge portion periphery 48 of the cathode separator 14 The thickness Tbc and the thickness Tba around the edge portion 48 of the anode-side separator 16 are set to have a relationship of Tam + Tac + Taa> Tbm + Tbc + Tba.

  More preferably, a relationship of Tam × 0.8 + Tac + Taa> Tbm + Tbc + Tba is set. More preferably, a relationship of Tam × 0.6 + Tac + Taa> Tbm + Tbc + Tba is set. In the state where the fuel cell 10 is tightened, the thickness (cell thickness) of the fuel cell 10 including the power generation unit 46 is compressed by the surface pressure to include the periphery 48 of the edge portion of the fuel cell 10. The dimension is the same as the thickness (cell thickness).

  In the edge portion periphery 48, the distance L1 from the outer peripheral end portion 20ae of the cathode electrode 20 on the short side to the inner peripheral side end portions of the recesses 14c and 16c, and the outer peripheral end portion 22ae of the anode electrode 22 on the long side. The distance L2 to the outer peripheral side end of the recesses 14c and 16c is set. The distances L1 and L2 are preferably set to 0.1 mm or more, more preferably set to 0.4 mm or more, and still more preferably set to 2 mm or more.

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

  First, 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. 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 from the oxidant gas inlet communication hole 30a into the oxidant gas flow path 36 of the cathode side separator 14, moves in the direction of arrow A, and is supplied to the cathode electrode 20 of the MEA 12a. On the other hand, the fuel gas is introduced into the fuel gas passage 38 of the anode separator 16 from the fuel gas inlet communication hole 34a. The fuel gas moves in the direction of arrow A along the fuel gas flow path 38 and is supplied to the anode electrode 22 of the MEA 12a.

  Therefore, in each MEA 12a, the oxidizing gas supplied to the cathode electrode 20 and the fuel gas supplied to the anode electrode 22 are consumed by an electrochemical reaction in the electrode catalyst layer to generate power.

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

  The cooling medium supplied to the cooling medium inlet communication hole 32 a is introduced into the cooling medium flow path 40 between the cathode separator 14 and the anode separator 16 and then flows in the direction of arrow A. After cooling the MEA 12a, the cooling medium is discharged from the cooling medium outlet communication hole 32b.

  In this case, in the first embodiment, as shown in FIG. 2, the cathode separator 14 is provided with a recess 14 c that accommodates the edge portion periphery 48 including the outer peripheral end portion 20 ae of the cathode electrode 20. Similarly, the anode-side separator 16 is provided with a recess 16c that accommodates an edge portion periphery 48 including the outer peripheral end portion 22ae of the anode electrode 22.

  At that time, as shown in FIG. 4, before the fuel cell 10 is tightened, the relationship of Tam + Tac + Taa> Tbm + Tbc + Tba is set. More preferably, Tam × 0.8 + Tac + Taa> Tbm + Tbc + Tba, and even more preferably Tam × 0.6 + Tac + Taa> Tbm + Tbc + Tba.

  For this reason, the surface pressure of the solid polymer electrolyte membrane 18 after tightening of the fuel cell 10 can be set such that the power generation portion surface pressure> the edge portion surface pressure. That is, as shown in FIG. 5, from the relationship between the thickness (cell thickness) of the fuel cell 10 and the surface pressure, the cell thickness after tightening corresponding to the desired power generation portion surface pressure and edge portion surface pressure is calculated. Is done.

  Therefore, when the fuel cell 10 is tightened, the tightening allowance around the edge portion 48 is set to be smaller than the tightening allowance in the power generation unit 46. Thereby, in the electric power generation part 46, while ensuring the surface pressure required in order to ensure electric power generation performance, in the edge part periphery 48, excessive clamping force is applied to the outer peripheral edge parts 20ae and 22ae of the electrode catalyst layers 20a and 22a. This can be suppressed.

  For this reason, while having desired power generation performance, the effect that it becomes possible to suppress well the damage of the solid polymer electrolyte membrane 18 by the outer peripheral edge parts 20ae and 22ae which are edge parts is acquired. In particular, as shown in FIG. 4, the distances L1 and L2 are preferably set to 0.1 mm or more, more preferably set to 0.4 mm or more, and further preferably set to 2 mm or more. . Therefore, damage to the solid polymer electrolyte membrane 18 is suppressed as much as possible.

  FIG. 6 is an exploded perspective view of a main part of a fuel cell 60 according to the second embodiment of the present invention. The same components as those of the fuel cell 10 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. Similarly, in the third and subsequent embodiments described below, detailed description thereof is omitted.

  The fuel cell 60 includes an electrolyte membrane / electrode structure 62 with a protective film, and a cathode side separator 64 and an anode side separator 66 that sandwich the electrolyte membrane / electrode structure 62 with a protective film.

  As shown in FIG. 7, an electrolyte membrane / electrode structure 62 with a protective film includes an MEA 62a. The MEA 62a includes a solid polymer electrolyte membrane 18 as a cathode electrode (second electrode) 68 and an anode electrode (first electrode). ) 70.

  The cathode electrode 68 is provided with an electrode catalyst layer 68a and a gas diffusion layer 68b, while the anode electrode 70 is provided with an electrode catalyst layer 70a and a gas diffusion layer 70b. The electrode catalyst layers 68 a and 70 a are set to have a smaller outer dimension than the solid polymer electrolyte membrane 18, and the gas diffusion layers 68 b and 70 b are set to the same outer dimensions as the solid polymer electrolyte membrane 18.

  The outer peripheral end portion 70ae of the electrode catalyst layer 70a constituting the anode electrode 70 is set to a dimension protruding outward in the electrode surface direction from the outer peripheral end portion 68ae of the electrode catalyst layer 68a constituting the cathode electrode 68. Contrary to the above configuration, the outer peripheral end portion 68ae of the cathode electrode 68 may be configured to protrude outward in the electrode surface direction from the outer peripheral end portion 70ae of the anode electrode 70.

  The electrolyte membrane / electrode structure 62 with a protective film is joined between both surfaces 18a, 18b of the solid polymer electrolyte membrane 18 and the gas diffusion layers 68b, 70b, and the inner peripheral edge side of each of them is an electrode catalyst. Protective films 72a and 72b made of a resin frame member joined between the layers 68a and 70a and the gas diffusion layers 68b and 70b are provided.

  The cathode-side separator 64 is provided with a concave portion 64c that accommodates an edge portion periphery 48 including an outer peripheral end portion 68ae (edge portion) at an outer peripheral edge portion in contact with the MEA 62a. The anode-side separator 66 is provided with a recess 66c that accommodates an edge portion periphery 48 including an outer peripheral end portion 70ae (edge portion) at an outer peripheral edge portion in contact with the MEA 62a.

  As shown in FIG. 8, before assembling the fuel cell 60, the thickness Tam of the power generation unit 46 of the electrolyte membrane / electrode structure 62 with a protective film, the thickness Tac of the power generation unit 46 of the cathode separator 64, and the anode side The thickness Taa of the power generation part 46 of the separator 66, the thickness Tbm of the edge part periphery 48 of the electrolyte membrane / electrode structure 62 with the protective film, the thickness Tbc of the edge part periphery 48 of the cathode separator 64, and the anode The thickness Tba around the edge portion 48 of the side separator 66 is set such that Tam + Tac + Taa> Tbm + Tbc + Tba.

  More preferably, a relationship of Tam × 0.8 + Tac + Taa> Tbm + Tbc + Tba is set. More preferably, a relationship of Tam × 0.6 + Tac + Taa> Tbm + Tbc + Tba is set. In the state where the fuel cell 60 is tightened, the thickness (cell thickness) of the fuel cell 60 including the power generation unit 46 is equal to the thickness (cell thickness) of the fuel cell 60 including the edge portion periphery 48. It becomes the same size.

  In the edge portion periphery 48, the distance L3 from the outer peripheral end portion 68ae of the cathode electrode 68 on the short side to the inner peripheral side end portions of the concave portions 64c and 66c, and the outer peripheral end portion 70ae of the anode electrode 70 on the long side. A distance L4 to the outer peripheral side end of the recesses 64c and 66c is set. The distances L3 and L4 are preferably set to 0.1 mm or more, more preferably set to 0.4 mm or more, and still more preferably set to 2 mm or more.

  In the second embodiment configured as described above, as shown in FIG. 7, the cathode-side separator 64 is provided with a recess 64 c that accommodates the edge portion periphery 48, and the anode-side separator 66 has the edge described above. A recess 66 c that accommodates the peripheral portion 48 is provided. Therefore, the fuel cell 60 has the desired power generation performance and can favorably suppress the breakage of the solid polymer electrolyte membrane 18 due to the outer peripheral end portions 68ae and 70ae as the edge portions. The same effect as that of the first embodiment can be obtained.

  FIG. 9 is an explanatory cross-sectional view of a main part of a fuel cell 80 according to the third embodiment of the present invention.

  The fuel cell 80 includes an electrolyte membrane / electrode structure 12 with a protective film, and a cathode side separator 82 and an anode side separator 84 that sandwich the electrolyte membrane / electrode structure 12 with a protective film.

  The cathode-side separator 82 is provided with a recess 82c that accommodates the edge portion periphery 48 including the outer peripheral end portion 20ae at the outer peripheral edge portion in contact with the MEA 12a. The anode side separator 84 is provided with a concave portion 84c that accommodates the edge portion periphery 48 including the outer peripheral end portion 22ae at the outer peripheral edge portion in contact with the MEA 12a. In the tightened state of the fuel cell 80, a gap S1 is formed between the inner wall surface of the recess 82c and the gas diffusion layer 20b, while a gap S2 is formed between the inner wall surface of the recess 84c and the gas diffusion layer 22b. .

  In the third embodiment configured as described above, the power generation performance is desired, and the breakage of the solid polymer electrolyte membrane 18 by the outer peripheral end portions 20ae and 22ae that are the edge portions can be satisfactorily suppressed. The same effects as those of the first and second embodiments are obtained.

  FIG. 10 is an explanatory cross-sectional view of a main part of a fuel cell 90 according to the fourth embodiment of the present invention.

  The fuel cell 90 includes an electrolyte membrane / electrode structure 62 with a protective film, and a cathode side separator 92 and an anode side separator 94 that sandwich the electrolyte membrane / electrode structure 62 with a protective film.

  The cathode-side separator 92 is provided with a concave portion 92c that accommodates the edge portion periphery 48 including the outer peripheral end portion 68ae at the outer peripheral edge portion in contact with the MEA 62a. The anode side separator 94 is provided with a concave portion 94c that accommodates the edge portion periphery 48 including the outer peripheral end portion 70ae at the outer peripheral edge portion in contact with the MEA 62a. In the tightened state of the fuel cell 90, a gap S3 is formed between the inner wall surface of the recess 92c and the gas diffusion layer 68b, while a gap S4 is formed between the inner wall surface of the recess 94c and the gas diffusion layer 70b. .

  In the fourth embodiment configured as described above, the power generation performance is desired, and the breakage of the solid polymer electrolyte membrane 18 by the outer peripheral end portions 68ae and 70ae that are the edge portions can be satisfactorily suppressed. The same effects as those of the first to third embodiments are obtained.

10, 60, 80, 90 ... fuel cell 12, 62 ... electrolyte membrane / electrode structure 12a, 62a with protective film ... MEA
14, 16, 64, 66, 82, 84, 92, 94 ... Separator 14c, 16c, 64c, 66c, 82c, 84c, 92c, 94c ... Recess 18 ... Solid polymer electrolyte membrane 20, 68 ... Cathode electrodes 20a, 22a , 68a, 70a ... electrode catalyst layers 20ae, 22ae, 68ae, 70ae ... outer peripheral ends 20b, 22b, 68b, 70b ... gas diffusion layers 22, 70 ... anode electrodes 24a, 24b, 72a, 72b ... protective film 30a ... oxidizing agent Gas inlet communication hole 30b ... Oxidant gas outlet communication hole 32a ... Cooling medium inlet communication hole 32b ... Cooling medium outlet communication hole 34a ... Fuel gas inlet communication hole 34b ... Fuel gas outlet communication hole 36 ... Oxidant gas flow path 38 ... Fuel Gas channel 40 ... cooling medium channel 46 ... power generation unit 48 ... around edge

Claims (5)

An electrolyte membrane / electrode structure in which a first electrode and a second electrode each having an electrode catalyst layer and a gas diffusion layer are provided on both sides of the solid polymer electrolyte membrane;
Separators disposed on both surfaces of the electrolyte membrane / electrode structure;
A fuel cell comprising:
The electrolyte membrane / electrode structure includes a power generation unit that sandwiches the solid polymer electrolyte membrane between the first electrode and the second electrode;
An edge portion sandwiching the solid polymer electrolyte membrane between the electrode catalyst layer outer peripheral ends of each of the first electrode and the second electrode;
Have
The fuel cell according to claim 1, wherein the separator is formed with a recess for accommodating the edge portion on a surface in contact with the electrolyte membrane / electrode structure.   2. The fuel cell according to claim 1, wherein an outer peripheral end portion of the electrode catalyst layer constituting the first electrode protrudes outward in an electrode surface direction from an outer peripheral end portion of the electrode catalyst layer constituting the second electrode. A fuel cell characterized by being set to.   3. The fuel cell according to claim 1, wherein a protective film is provided on an outer periphery of the gas diffusion layer.   3. The fuel cell according to claim 1, wherein a protective film is provided between the solid polymer electrolyte membrane and the gas diffusion layer.   5. The fuel cell according to claim 1, wherein, when the fuel cells are stacked, a gap between the electrolyte membrane / electrode structure and the separator is more outward in the electrode surface direction than the edge portion. 6. In the fuel cell, a gap is formed.

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