JP6172510B2 - Single cell for fuel cell - Google Patents

Description

  The present invention relates to a unit cell for a fuel cell in which a plurality of sheets are stacked to form a fuel cell stack, and more particularly to a unit cell for a fuel cell including a membrane electrode assembly having a frame around it.

  As this type of single cell for a fuel cell, there is one described in Patent Document 1 under the name of the fuel cell and its manufacturing method. The fuel cell described in Patent Document 1 includes a membrane electrode assembly (MEA) having a resin frame around it. The membrane / electrode assembly includes a cathode-side catalyst layer and a diffusion layer laminated on one surface of an electrolyte membrane, and an anode-side catalyst layer and diffusion layer on the other surface, and sandwiches the peripheral portion thereof. Thus, a resin frame is formed.

  The fuel cell has a structure in which the frame and the membrane electrode assembly are sandwiched between separators on the cathode side and the anode side. The fuel cell stack is configured by stacking a plurality of fuel cells and applying a predetermined load in the stacking direction.

JP 2008-146872 A

  By the way, in this type of fuel cell unit cell, since the membrane electrode assembly and the resin frame, which are different materials, are integrated with each other, the electrolyte membrane swells and contracts, and the difference in gas between the anode side and the cathode side occurs. If stress concentration occurs at the joint between the membrane electrode assembly and the resin frame due to pressure or the like, the membrane electrode assembly may be damaged. In particular, a relatively weak electrolyte membrane may be damaged in the membrane electrode assembly.

  In contrast, the fuel cell of Patent Document 1 has a structure in which the joint between the membrane electrode assembly and the resin frame is sandwiched between a pair of separators, but the joint can be sufficiently restrained in the thickness direction. However, there is a possibility that stress concentration may still occur in the joint portion, and it has been a problem to solve such problems.

  The present invention has been made paying attention to the above-mentioned conventional problems, and is a single cell for a fuel cell including a membrane electrode assembly having a frame around it, and includes at least a junction between an electrolyte membrane and a frame. It aims at providing the single cell for fuel cells which can prevent that stress concentration arises in an area | region.

A fuel cell single cell according to the present invention is a fuel cell single cell comprising a plurality of stacked fuel cell stacks, the membrane having a structure in which an electrolyte membrane is sandwiched between a pair of electrode layers having a catalyst layer An electrode assembly, a frame formed around the membrane electrode assembly, and a pair of separators that form a gas flow path between the frame and the membrane electrode assembly are provided. Then, the single cell joint between the electrolyte membranes and the frame of the membrane electrode assembly, and bonding for restraining the area of the end portion in the thickness direction including the junction between the catalyst layer and the frame of each electrode layer As a means for solving a conventional problem with the above-mentioned structure, it has a part restraining means and a pressing force applying means for applying a pressing force in the thickness direction to the region of the end including the joint part. Yes.

Since the fuel cell single cell of the present invention employs the above-described configuration , even if the electrolyte membrane swells and contracts, or the gas pressure difference between the anode side and the cathode side occurs, the membrane electrode assembly and the frame The thickness of the joint between the electrolyte membrane and the frame, which is the weakest part of the entire joint , and the end region including the joint between the catalyst layer and the frame of each electrode layer is maintained in the thickness direction. By absorbing the displacement in the direction , stress concentration can be prevented from occurring at the junction between the power generation area of the membrane electrode assembly and the frame, and as a result, the membrane electrode assembly can be protected.

It is the perspective view (A) explaining the fuel cell stack provided with the single cell for fuel cells of this invention, and the perspective view (B) of a decomposition | disassembly state. It is sectional drawing (A) of the principal part of the single cell explaining 1st Embodiment, and the enlarged view (B) of a membrane electrode assembly. It is a top view of a single cell. It is a graph which shows the relationship between the spring constant of a spring mechanism, and the generated stress reduction rate. It is the top view (A) of the single cell explaining 2nd Embodiment, and sectional drawing (B) of the principal part of a single cell. It is a perspective view explaining the spring mechanism as a pressing force provision means shown in FIG. It is the top view (A) of the single cell explaining 3rd Embodiment, and sectional drawing (B) of the principal part of a single cell.

<First Embodiment>
A fuel cell FC shown in FIG. 1 includes a laminated body (fuel cell stack) S formed by laminating a plurality of rectangular plate-shaped fuel cell single cells (hereinafter referred to as “single cells”) C. In the fuel cell FC, an end plate 56A is provided at one end (the right end in FIG. 1B) in the stacking direction of the stack S via a current collecting plate 54A and a spacer 55, and at the other end. An end plate 56B is provided via a current collecting plate 54B. Further, the fuel cell FC is provided with fastening plates 57A and 57B on both surfaces (upper and lower surfaces in FIG. 1B) on the long side of the single cell C with respect to the stacked body S, and on both surfaces on the short side. Further, reinforcing plates 58A and 58B are provided.

  In the fuel cell FC, the fastening plates 57A and 57B and the reinforcing plates 58A and 58B are connected to both end plates 56A and 56B by bolts B. As a result, the fuel cell FC has a case-integrated structure shown in FIG. 1A. The stack S is constrained and pressurized in the stacking direction to apply a predetermined contact surface pressure to each single cell C, and a gas seal. Good maintainability and conductivity.

In the fuel cell FC described above, the unit cell C constituting the stacked body S includes a membrane electrode assembly M having a structure in which the electrolyte membrane 1 is sandwiched between a pair of electrode layers 2 and 3, as shown in FIG. A frame F formed around the electrode assembly M and a pair of separators 4 and 4 that form gas flow paths G and G between the frame F and the membrane electrode assembly M are provided.

  The membrane electrode assembly M is a so-called MEA (Membrane Electrode Assembly) in which an electrolyte membrane 1 made of a solid polymer is sandwiched between electrode layers 2 and 3 on the anode side and the cathode side. The frame F is made of resin and is integrated with the membrane electrode assembly 1 by, for example, injection molding. The electrode layers 2 and 3 on the anode side and the cathode side will be described in detail later.

  Each of the separators 4 and 4 is made of stainless steel, for example, and as shown in FIG. 1B, the central region corresponding to the membrane electrode assembly M is formed in a wave shape. At this time, the separator 4 has a wave-shaped cross section that is continuous in the long side direction, and the gas flow path G that is continuous in the long side direction between the wave-shaped cross section and the membrane electrode assembly M. Each G is formed.

  Moreover, each separator 4 is formed in the reverse side shape, for example by press work. Therefore, each separator 4 is in contact with the membrane electrode assembly M by the convex portion and the gas flow path G is formed by the concave portion on the cell inner surface side which is the membrane electrode assembly M side. On the cell outer surface side, the convex and concave portions on the cell inner surface side are conversely concave and convex.

  As shown in FIG. 3, the frame F of the membrane electrode assembly M and the separators 4 are provided with manifold holes H1 to H3 for flowing the reaction gas and the cooling fluid along the short sides on both sides. H4 to H6. The reaction gas is an anode gas (hydrogen-containing gas) and a cathode gas (air), and the cooling fluid is water as an example.

  On one short side shown in the left side of FIG. 3, the manifold holes H1 to H3 are for anode gas supply (H1), cooling fluid discharge (H2), and cathode gas discharge (H3) from the upper side. The respective flow paths are formed in communication with each other in the stacking direction. Further, on the other short side shown on the right side of FIG. 3, each of the manifold holes H4 to H6 has a cathode gas supply (H4), a cooling fluid supply (H5), and an anode gas discharge (H6) from the upper side. Each channel is formed in communication with each other in the stacking direction. These manifold holes H1 to H6 can change the type of fluid, the positional relationship between supply and discharge, and the like with respect to the above configuration.

  A gas seal (not shown) is provided between the edges of the separator 4 and the frame F and around the manifold holes H1 to H6. In a state where a plurality of single cells C are stacked, a gas seal is also provided between the single cells C, that is, between adjacent separators 4. This gas seal hermetically separates the flow areas of the cathode gas, the anode gas and the cooling fluid between the individual layers, and applies the corresponding manifold holes H1 to H6 so that a predetermined fluid flows between the layers. An opening is provided at an appropriate location on the peripheral edge of the.

  In the single cell C constituting the fuel cell FC, each electrode layer 2, 3 of the membrane electrode assembly M has a catalyst layer 2 A, 3 A and a porous layer from the electrolyte membrane 1 side as shown in FIG. First gas diffusion layers 2B and 3B made of a material and second gas diffusion layers 2C and 3C made of a metal porous body are sequentially provided.

  The first gas diffusion layers 2B and 3B are made of, for example, a carbon material. Specifically, the first gas diffusion layers 2B and 3B are obtained by solidifying a random laminate of carbon fibers with a binder and applying a water repellent treatment such as PTFE, or agglomerates such as carbon black such as PTFE. Sintered with a binder.

  The second gas diffusion layers 2C and 3C are metal porous bodies that are distinguished from the porous bodies forming the first gas diffusion layers, and have conductivity. For the second gas diffusion layers 2C and 3C, use one or more kinds of metals of iron, stainless steel, aluminum and aluminum alloy, chromium and chromium alloy, nickel and nickel alloy, and magnesium and magnesium alloy. Can do. Further, the second gas diffusion layers 2C and 3C are concretely a metal mesh, a punching metal, an etching metal, an expanded metal, or the like, and in this embodiment, is a metal mesh as shown in FIG.

  Here, as shown in FIG. 2, the membrane electrode assembly M in the single cell C of this embodiment has an arrangement in which the end of each layer is shifted in the in-plane direction (the direction along the plane which is the left-right direction in FIG. 2). It has become. That is, with respect to the end portion of the electrolyte membrane 1, the end portion of the upper anode catalyst layer 2A is located on the inner side (left side in FIG. 2). The end of the lower cathode catalyst layer 3 </ b> A is at the same position as the end of the electrolyte membrane 1.

  Further, the end portions of the anode-side first and second gas diffusion layers 2B, 2C and the cathode-side first and second gas diffusion layers 3B, 3C with respect to the end portion of the electrolyte membrane 1 are , Located outside (right side in FIG. 2) and in the same position. The anode side and the cathode side may be upside down. The frame F is integrally formed with the membrane electrode assembly M in which the end portions of the respective layers are shifted as described above.

  In the unit cell C, in addition to the membrane electrode assembly M, the frame F, and the separator 4, a region including at least the junction between the electrolyte membrane 1 and the frame F in the membrane electrode assembly M is constrained in the thickness direction. And a pressing force applying means for applying a pressing force in the thickness direction to the region including the bonding portion.

  The single cell C of this embodiment has a junction portion with respect to the junction portion between the active area (power generation area) of the membrane electrode assembly M and the frame F in the entire junction portion of the membrane electrode assembly M and the frame F. It is provided with restraining means and pressing force applying means. The active area of the membrane electrode assembly M is an area composed of at least the electrolyte membrane 1 and the two catalyst layers 2A and 3A.

  Therefore, as shown in FIG. 2 (B), the target joints in this embodiment are the joint P1 between the anode side catalyst layer 2A and the frame F, the electrolyte membrane 1, the cathode side catalyst layer 3A, and the frame F. It is the junction part P2. Therefore, the joining part restraining means restrains the area AP including both joining parts P1 and P2 in the thickness direction. Further, the pressing force applying means applies a pressing force in the thickness direction to the region AP including both the joint portions P1 and P2.

  The joining portion restraining means is constituted by a part of the separator 4 and at least one porous body disposed on the surface side of the electrode layers 2 and 3, and the porous body is a metallic porous body. Specifically, the joining portion restraining means includes the convex portion 4A on the cell inner surface side of the separator 4 shown in FIG. 2A and the first and second gases extending outward from both the joining portions P1 and P2. The diffusion layers 2B, 2C, 3B, and 3C are configured. The second gas diffusion layers 2C and 3C are metal porous bodies (wire nets) as described above. In this embodiment, the second gas diffusion layers 2B and 3B together with the second gas diffusion layers 2C and 3C also constitute the joint restraint means.

  The pressing force applying means is a spring mechanism 5 interposed between the single cells C in the laminate (fuel cell stack) S, and the spring constant of the spring mechanism 5 is 2000 N / cm or more. Yes. As shown in FIG. 2 (A), the spring mechanism 5 has a large number of spring function portions 5B arranged at a predetermined interval on a substrate 5A, and is loaded in the stacking direction of the pressing force applying means and the single cell C. It also serves as a means for imparting. In the laminate S, a cooling fluid flow path R is formed between the single cells C.

  The spring function part 5B in the spring mechanism 5 is, for example, a tongue-like plate spring having a base end as a fixed end and a tip end as a free end. And the spring mechanism 5 has the convex part 4A on the cell inner surface side of the separator 4 which is the front and back inverted shape, that is, the spring function part 5B that comes into contact with the bottom surface of the concave part on the cell outer surface side. A pressing force is applied in the thickness direction to the region AP including both the joints P1 and P2.

  The single cell C having the above-described configuration is the weakest part of the entire junction between the membrane electrode assembly M and the frame F, that is, at least the region AP including the junction P2 between the electrolyte membrane 1 and the frame F. In addition, since the joint restraining means and the pressing force applying means are provided, even if the electrolyte membrane 1 swells and contracts, or the gas pressure difference between the anode side and the cathode side occurs, at least the electrolyte membrane 1 and the frame F It is possible to prevent stress concentration from occurring in the region AP including the joint portion P2.

  Further, in the single cell C of this embodiment, not only the joint P2 between the electrolyte membrane 1 and the frame F but also the stress at the joints P1 and P2 between the active area (power generation area) of the membrane electrode assembly M and the frame F Concentration is prevented.

  More specifically, the region AP including both the joints P1 and P2 is formed by the convex part 4A of the separator 4 as the joint restraint means and the first and second gas diffusion layers 2B, 2C, 3B, and 3C. Since the pressing force is applied in the thickness direction to the region AP by the spring mechanism 5 serving as a pressing force applying means, the electrolyte membrane 1 is swollen and contracted, and the anode side is restrained in the thickness direction. Even if a differential pressure of gas from the cathode side occurs, the region AP including both the joints P1 and P2 can be sufficiently retained to prevent stress concentration, and as a result, the membrane electrode assembly M can be protected. It will be a thing.

  Moreover, since said single cell C comprised the junction part restraint means with the porous body arrange | positioned on the surface side of a part of separator 4 and the electrode layers 2 and 3, using the existing component, The effect of preventing stress concentration in the region AP including both the joints P1 and P2 can be obtained, which can contribute to the reduction of the manufacturing cost.

  Further, in the single cell C, since the porous body constituting the joint restraining means is a metal porous body (second gas diffusion layers 2C and 3C), the rigidity of the surface of the electrode layers 2 and 3 is increased. Since the pressing force of the pressing force applying means is applied to the porous metal body, it is possible to further improve the function of holding both the joint portions P1 and P2.

  Further, in the single cell C, since the pressing force applying means is the spring mechanism 5 interposed between the single cells C (flow path R) in the stacked body S, the means for applying a load in the stacking direction. And the pressing force applying means can be constituted by common parts. As a result, the effect of preventing stress concentration by sufficiently holding both the joints P1 and P2 can be obtained without using special parts, which can contribute to reduction in manufacturing costs.

  Furthermore, as shown in FIG. 4, the single cell C can reduce the generated stress at the joints P <b> 1 and P <b> 2. FIG. 4 is a graph showing the relationship between the spring constant of the spring mechanism 5 and the generated stress reduction rate. In the single cell C, the spring constant of the spring mechanism 5 is 2000 N / cm or more. As is clear from FIG. 4, when the spring constant is 2000 N / cm or more, the stress concentration sensitivity (change in the generated stress reduction rate) decreases, and a stable holding function can be obtained.

  In the fuel cell stack (stacked body S) formed by stacking the single cells C, the membrane electrode assembly M is protected in each single cell C, and good power generation performance can be maintained over a long period. In addition, it is possible to reduce the number of parts and the manufacturing cost.

Second Embodiment
5 and 6 are diagrams illustrating a second embodiment of the present invention. In the following embodiments, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  The single cell C shown in FIG. 5A has a joint P between the membrane electrode assembly M and the frame 1 along the gas flow direction of the gas flow path indicated by the arrow in the drawing.

  In the single cell C, as shown in FIG. 5 (B), the end of each layer forming the membrane electrode assembly M at the junction P is different from the first embodiment at the end of the electrolyte membrane 1. On the other hand, the end portions of the catalyst layers 2A and 3A on the anode side and the cathode side are located on the inner side (left side in FIG. 5). Further, the end portions of the first and second gas diffusion layers 2B, 2C, 3B, and 3C are located outside the end portion of the electrolyte membrane 1. A gap between the peripheral portions of the membrane electrode assembly M and the separator 4 is sealed with a sealing material 6.

  The single cell C of this embodiment includes at least a joint part P3 between the electrolyte membrane 1 and the frame F, and joint parts P4 and P5 between the catalyst layers 2A and 3A and the frame F in the membrane electrode assembly M. A joining portion restraining means for restraining the region AP in the thickness direction, and a pressing force applying means for applying a pressing force in the thickness direction to the region including the joining portion are provided. Said junction part P3-P5 is a junction part of the active area (power generation area) of the membrane electrode assembly M and the flame | frame F similarly to 1st Embodiment.

  The joining portion restraining means is constituted by a part of the separator 4 and a metallic porous body disposed on the surface side of the electrode layers 2 and 3. Specifically, the joining part restraining means includes the convex part 4A on the cell inner surface side of the separator 4 and the first and second gas diffusion layers 2B, 2C, 3B extending outside the joining parts P3 to P5. It is composed of 3C.

  Here, a cooling fluid flow path R is formed between adjacent single cells C at the time of stacking, that is, between adjacent separators 4 and 4 in FIG. The flow direction of the cooling fluid in the flow path R is the same as the gas flow direction shown in FIG. 5A, and is the direction perpendicular to the paper surface in FIG.

  The pressing force applying means is a spring mechanism 15 interposed between the single cells C in the stacked body (fuel cell stack) S. As shown in FIG. 6, the spring mechanism 15 is configured by vertically and horizontally arranging tongue-like spring function portions 15 </ b> B on a substrate 15 </ b> A. Further, the spring mechanism 15 has an extended portion 15C continuous with the substrate 15A and spring pieces 15D and 15E bent upward and downward continuously with the extended portion 15C at a predetermined interval on the side of the substrate 15A. Have. And between the adjacent separators 4 and 4, the spring mechanism 15 arrange | positions the extension part 15C and the upper and lower spring pieces 15D and 15E between the recessed parts used as the back side of the convex part 4A of the cell inner surface side. Yes.

  In the stacked body (fuel cell stack) S, the spring mechanism 15 is interposed between the single cells C (flow path R), thereby applying the pressing force applying means and means for applying a load in the stacking direction. Is also used.

  Further, the extension portion 15C and the spring pieces 15D and 15E in the spring mechanism 15 suppress the side flow of the fluid in the flow path R of the cooling fluid. That is, since the flow path R has spaces between the concave portions on the opposite sides of the convex portions 4A on both sides of the active area, the cooling fluid can easily flow into the spaces, and so-called side flow is generated. This may cause a decrease in the cooling efficiency of the active area.

  On the other hand, the spring mechanism 15 arranges the extending portion 15C and the spring pieces 15D and 15E as obstacles in the space so that the cooling fluid flows mainly in the active area. The protruding portion 15C and the spring pieces 15D and 15E are used as pressing force applying means to apply a pressing force in the thickness direction to the region AP including the joint portion.

  The single cell C having the above-described configuration is configured such that the electrolyte membrane 1 swells and contracts, and the anode side and the cathode at the joint P between the membrane electrode assembly M and the frame 1 that exist along the gas flow direction of the gas flow path. Even if a gas differential pressure or the like occurs, the region AP including at least the joint portion P3 between the electrolyte membrane 1 and the frame F can be sufficiently retained to prevent stress concentration, and as a result, the membrane electrode assembly M can be protected.

  In the single cell C, the pressing force applying means and the means for applying a load in the stacking direction are constituted by a common spring mechanism 15, so that the joints P3 to P5 are sufficiently held without using special parts. Thus, the effect of preventing stress concentration can be obtained, and the manufacturing cost can be reduced.

<Third Embodiment>
In the single cell C shown in FIG. 7A, the junction P between the membrane electrode assembly M and the frame 1 intersects the gas flow direction of the gas flow path indicated by the arrow in the figure (vertical direction in FIG. 7). As shown in FIG. 7B, the same basic configuration as that of the second embodiment is provided. FIG. 7B is a cross-sectional view at the position of the convex portion on the cell inner surface of the separator 4. Therefore, a gas flow path is formed by the concave portion on the inner surface of the cell that does not appear in FIG. 7B, and a flow path R for the cooling fluid is formed outside the cell of the separator 4. The flow direction of the reaction gas and the cooling fluid is the left-right direction in FIG.

  Similar to the previous embodiment, the unit cell C having the above-described configuration has at least the electrolyte membrane 1 and the frame even if the electrolyte membrane 1 swells and contracts and the gas pressure difference between the anode side and the cathode side occurs. The region AP including the joint portion P3 with F can be sufficiently held to prevent stress concentration, and as a result, the membrane electrode assembly M can be protected. In addition, the single cell C can obtain the effect of preventing stress concentration by sufficiently holding the region AP including the joint portions P3 to P5 without using special parts by adopting the spring mechanism 15. It can also contribute to the reduction of manufacturing costs.

  The single cell for a fuel cell according to the present invention is not limited to the above-described embodiments, and the details of each component can be changed without departing from the gist of the present invention. . For example, in the single cell, the number and materials of layers constituting each electrode layer can be changed. Furthermore, although the joint part restraining means demonstrated the case where the porous body which forms the surface side of an electrode layer was employ | adopted in each embodiment, it is also possible to use a member with an electrode layer. Furthermore, even if it exists in a pressing force provision means, components other than the spring mechanism shown in each embodiment can be used.

C fuel cell single cell F frame G gas flow path M membrane electrode assembly P, P1 to P5 joint R flow path for cooling fluid S laminate (fuel cell stack)
DESCRIPTION OF SYMBOLS 1 Electrolyte membrane 2 Anode-side electrode layer 2A, 3A Catalyst layer 2B, 3B 1st gas diffusion layer (joining part restraint means)
2C, 3C second gas diffusion layer (bonding part restraining means: metal porous body)
3 Electrode layer on the cathode side 4 Separator 4A Separator convex part (joining part restraining means)
5,15 Spring mechanism (pressing force applying means)

Claims (12)

A single cell for a fuel cell comprising a plurality of stacked fuel cell stacks,
A membrane electrode assembly having a structure in which an electrolyte membrane is sandwiched between a pair of electrode layers having a catalyst layer ;
A frame formed around the membrane electrode assembly;
A pair of separators forming a gas flow path between the frame and the membrane electrode assembly;
Junction between the electrolyte membranes and the frame of the membrane electrode assembly, and a joining portion restraining means for restraining the area of the end portion in the thickness direction including the junction between the catalyst layer and the frame of the electrode layers,
A single cell for a fuel cell, comprising a pressing force applying means for applying a pressing force in a thickness direction to an end region including the joint.   2. The single cell for a fuel cell according to claim 1, wherein the joining portion restraining means includes a part of the separator and a porous body disposed on a surface side of the electrode layer.   The single cell for a fuel cell according to claim 1 or 2, wherein a junction between the membrane electrode assembly and the frame is provided along a gas flow direction of the gas flow path.   The single cell for a fuel cell according to any one of claims 1 to 3, further comprising a junction between the membrane electrode assembly and the frame along a direction intersecting a gas flow direction of the gas flow path. . The single cell for a fuel cell according to claim 2, wherein the porous body constituting the joint restraining means is a metallic porous body.   The single cell for a fuel cell according to any one of claims 1 to 5, wherein the pressing force applying means is a spring mechanism interposed between the single cells in the fuel cell stack.   The single cell for a fuel cell according to claim 6, wherein a spring constant of the spring mechanism is 2000 N / cm or more. A single cell for a fuel cell comprising a plurality of stacked fuel cell stacks,
A membrane electrode assembly having a structure in which an electrolyte membrane is sandwiched between a pair of electrode layers;
A frame formed around the membrane electrode assembly;
A pair of separators forming a gas flow path between the frame and the membrane electrode assembly;
A joint restraint means for restraining at least a region including a joint between the electrolyte membrane and the frame in the membrane electrode assembly;
A pressing force applying means for applying a pressing force in the thickness direction to the region including the joint portion;
A single cell for a fuel cell, wherein the joint restraint means is constituted by a part of a separator and a porous body disposed on the surface side of an electrode layer.   The single cell for a fuel cell according to claim 8, wherein the porous body constituting the joint restraining means is a metal porous body. A single cell for a fuel cell comprising a plurality of stacked fuel cell stacks,
A membrane electrode assembly having a structure in which an electrolyte membrane is sandwiched between a pair of electrode layers;
A frame formed around the membrane electrode assembly;
A pair of separators forming a gas flow path between the frame and the membrane electrode assembly;
A joint restraint means for restraining at least a region including a joint between the electrolyte membrane and the frame in the membrane electrode assembly;
A pressing force applying means for applying a pressing force in the thickness direction to the region including the joint portion;
A single cell for a fuel cell, wherein the pressing force applying means is a spring mechanism interposed between the single cells in the fuel cell stack.   The single cell for a fuel cell according to claim 10, wherein a spring constant of the spring mechanism is 2000 N / cm or more. A fuel cell stack comprising the fuel cell unit cells according to any one of claims 1 to 11 stacked.

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