JP6593156B2 - Fuel cell separator - Google Patents

Description

  The present invention relates to a fuel cell separator.

  A fuel cell includes a membrane electrode assembly (MEA) in which anode and cathode electrode catalyst layers are joined to both membrane surfaces of an electrolyte membrane, and a fuel cell separator (hereinafter also referred to as a separator) with a seal member interposed therebetween. To hold). In such a structure, there has been proposed a technique for improving the sealing performance between the separator and the sealing member by defining the surface roughness of the sealing region where sealing is required in the separator (for example, Patent Document 1). The MEA is used in the form of MEGA (Membrane-Electrode & Gas. Diffusion Layer Assembly) sandwiched between gas diffusion layers that allow gas diffusion and transmission. Even in this form, a seal member is interposed, MEGA is sandwiched between separators.

JP 2003-132913 A

  Since the fuel cell is mounted on a vehicle to serve as a driving force generation source or incorporated in a power generation device to serve as a power generation source, operation for a long period is planned. For this reason, it is calculated | required that the secular deterioration is suppressed also about the sealing performance of a separator and a sealing member. However, in the sealing method proposed in the above-mentioned patent document, no effort has been made for the aging deterioration of the sealing performance between the separator and the sealing member, and the surface roughness of the sealing area is regulated to suppress the aging deterioration of the sealing performance. Suspicions remain about whether or not For these reasons, it has been requested to suppress the aging deterioration of the sealing performance between the separator and the sealing member.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms.

(1) According to one aspect of the present invention, a fuel cell separator is provided. The fuel cell separator is a bond to a fuel cell separator used in the seal member for holding the membrane electrode assembly formed by joining the electrode catalyst layer on both the membrane surface of the electrolyte membrane, titanium consists Chita down plate or Rannahli, arithmetic surface roughness Ra of the separator surface is a 0.2μm or less, the crystal grain size of the separator surface is 20 to 50 m. The fuel cell separator of this embodiment is used by adhering to the sealing material with an adhesive capable of exhibiting the adhesion function of the fuel cell separator to the seal member. According to the fuel cell separator of this embodiment, the fuel cell separator and the sealing member adhered by the adhesive by selecting the base material and defining the arithmetic surface roughness Ra and the crystal grain size of the separator surface. It was confirmed that the sealing property can be expressed and the deterioration of the sealing property over time can be suppressed. This arithmetic surface roughness Ra of the surface of the separator which definitive in titanium Plates and 0.2μm or less, the crystal grain size that is defined as 20 to 50 m, the peeling of the adhesive at the interface between the fuel cell separator adhesives It is assumed that the increase in area can be suppressed over a long period of time. Then, the arithmetic surface roughness Ra or exceed 0.2μm separator surface definitive in titanium Plates, crystal grain size is non- range of 20 to 50 m, the adhesive at the interface of the separator and the adhesive for fuel cells It is assumed that the peel area increases or the peel area increases with time, and the sealing performance deteriorates over time.

  Note that the present invention can be realized in various modes. For example, it can be realized in the form of a fuel cell manufacturing method or manufacturing apparatus.

It is explanatory drawing which decomposes | disassembles and shows schematic structure of the fuel cell which comprises the fuel cell of embodiment. It is explanatory drawing which shows roughly the principal part site | part of a fuel cell along the 2-2 line in FIG. It is explanatory drawing which shows typically the mode of adhesion | attachment of the test piece with which it uses for a deterioration test. It is explanatory drawing which displays a list of sample classification, the state of surface property, and a test result. It is a graph which shows the relationship between the interface peeling area and shear strength which were obtained by the deterioration test. It is a graph which shows the relationship between the arithmetic mean roughness Ra of the surface of a 2nd test piece, and the interface peeling area obtained by the deterioration test. It is a graph which shows the relationship between arithmetic mean roughness Ra of the surface of a 2nd test piece, and the shear strength obtained by the deterioration test. It is a graph which shows the relationship between the crystal grain diameter of the surface of a 2nd test piece, and the interface peeling area obtained by the deterioration test. It is a graph which shows the relationship between the crystal grain diameter of the surface of a 2nd test piece, and the shear strength obtained by the deterioration test.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory view showing an exploded schematic view of a fuel cell 10 constituting the fuel cell 100 of the embodiment, and FIG. 2 is a main part of the fuel cell 10 taken along line 2-2 in FIG. It is explanatory drawing which shows a site | part schematically and shows it in cross section. In FIG. 1, the separators 41 and 42 constituting the fuel cell 10 are not shown, but the fuel cell 100 has a stack structure in which a plurality of fuel cells 10 sandwiched between the separators 41 and 42 shown in FIG. 2 are stacked. Yes. 2 does not reflect the actual thickness or the like of the constituent members.

  As shown in FIG. 2, the fuel cell 10 comprises a MEGA 26 by sandwiching a membrane electrode assembly 20 (hereinafter also simply referred to as MEA) between a cathode side gas diffusion layer 24 and an anode side gas diffusion layer 25. The MEGA 26 is held by a resin sheet 30 as a seal member. The membrane electrode assembly 20 includes both electrodes of a cathode 22 and an anode 23 on both sides of an electrolyte membrane 21. The electrolyte membrane 21 is a proton conductive ion exchange membrane formed of a solid polymer material, for example, a fluorine-based resin, and exhibits good electrical conductivity in a wet state. The anode 23 and the cathode 22 are formed by coating conductive particles carrying a catalyst such as platinum or a platinum alloy, for example, carbon particles (hereinafter referred to as catalyst-carrying carbon particles) with an ionomer having proton conductivity. The electrode catalyst layer is joined to both membrane surfaces of the electrolyte membrane 21 to form an MEA. Usually, the ionomer is a polymer electrolyte resin (for example, a fluorine-based resin) that is a solid polymer material of the same quality as the electrolyte membrane 21, and has proton conductivity due to the ion exchange group that the ionomer has.

  Both the gas diffusion layers of the cathode side gas diffusion layer 24 and the anode side gas diffusion layer 25 are conductive members having gas permeability, for example, a carbon porous body such as carbon paper or carbon cloth, a metal mesh, a foam metal, etc. It is formed by the metal porous body. Both gas diffusion layers are bonded to corresponding electrodes (cathode 22 or anode 23), and constitute MEGA 26 together with the membrane electrode assembly 20. In the fuel cell 10 of the present embodiment, as shown in FIG. 1, the membrane electrode assembly 20 and the MEGA 26 are both rectangular, and the anode 23 is approximately the same size as the electrolyte membrane 21 as shown in FIG. The cathode 22 is narrower than the anode 23 both vertically and horizontally. In the fuel cell 10, the anode side gas diffusion layer 25 is bonded to the entire surface of the anode 23, and the cathode side gas diffusion layer 24 is bonded to almost the entire surface of the cathode 22 to form the MEGA 26.

  The resin sheet 30 is molded so as to form a frame shape using a thermoplastic resin, and the central opening region 31 is used as a holding region of the MEGA 26. The resin sheet 30 has a stepped peripheral edge portion surrounding the opening region 31 and a stepped portion 32 as a MEGA receiving seat. Then, by setting the MEGA 26 on the stepped portion 32, the stepped portion 32 is formed on the side of the cathode 22 which is one film surface of the membrane electrode assembly 20, as shown in FIG. Overlapping the peripheral area. In this state, the resin sheet 30 holds the MEGA 26. In this state, the cathode-side gas diffusion layer 24 of the MEGA 26 is bonded to the cathode 22 of the membrane electrode assembly 20 in the opening region 31 (see FIG. 1).

  The resin sheet 30 includes a step portion 32 and a frame portion 33 surrounding the step portion 32 in a three-layer structure, and has surface layer portions 30a and 30b on the front and back of the core portion 30c. The surface layer portions 30a and 30b are made of an adhesive capable of exhibiting an adhesion function of the later-described separators 41 and 42 to the resin sheet 30, specifically, the core portion 30c, such as ethylene propylene rubber (EPDM) or thermoplastic polypropylene ( polypropylene (PP), which is melted in the process of manufacturing the fuel cell and cured through subsequent curing, so that at the stepped portion 32, the cathode 22 of the membrane electrode assembly 20 and the electrolyte membrane 21 in the surrounding region are formed. Adhesion is performed for sealing, and the front and back of the frame part 33 are adhered to separators 41 and 42 described later for sealing. With the MEGA 26 held as described above, the resin sheet 30 surrounds the outer peripheral wall of the cathode-side gas diffusion layer 24 and the outer peripheral wall of the electrolyte membrane 21 and the anode 23 as shown in FIG.

  As shown in FIG. 1, the resin sheet 30 includes a frame portion 33, a fuel gas supply hole 34 a and a discharge hole 34 b, a cooling water supply hole 35 a and a discharge hole 35 b, an air supply hole 36 a and a discharge hole. 36b. Moreover, the resin sheet 30 has the recessed part 37 and convex part 38a, 38b in the frame part 33, as shown in FIG. The concave portion 37 and the convex portions 38a and 38b are formed following the concave-convex shape of the separator 42 described later, have a surface layer portion 30b on the surface layer, and adhere to the separator 41 and the separator 42. The convex portion 38 a surrounds the power generation region of the MEGA 26 on the anode side gas diffusion layer 25 side. The convex portion 38b surrounds the supply hole 35a on the anode side gas diffusion layer 25 side. In addition, the convex part 38b is provided for every said supply / discharge hole. Since the above-mentioned supply / exhaust hole is the same as the existing configuration, description of the function and the like of the supply / exhaust hole is omitted.

  The separator 41 is laminated on the cathode side gas diffusion layer 24 to form an in-cell air flow path 41a, and the separator 42 is laminated on the anode side gas diffusion layer 25 to form an in-cell fuel gas flow path 42a. . The separators 41 and 42 are, for example, titanium plates formed with a steel plate having a thickness of 0.1 to 0.15 mm using pure titanium specified in JIS H4600, and have conductivity and are gas-impermeable. is there. The separator 41 is bonded and fixed to the frame portion 33 of the resin sheet 30 by the surface layer portion 30a of the resin sheet 30 after being bonded to the cathode side gas diffusion layer 24 and the resin sheet 30 and sealed. The separator 42 is bonded and fixed to the frame portion 33 of the resin sheet 30 by the surface layer portion 30b of the resin sheet 30 after being bonded to the cathode side gas diffusion layer 24 and the resin sheet 30 and sealed.

  The separator 42 includes recesses 42b and 42c on the outside of the in-cell fuel gas passage 42a, and a space between the recesses serves as a seal receiving seat 42d. The separator 42 causes the convex portion 38a of the resin sheet 30 to enter the concave portion 42b, causes the convex portion 38b of the resin sheet 30 to enter the concave portion 42c, and causes the concave portion 37 of the resin sheet 30 to face the seal receiving seat 42d. The surface layer portion 30b of the resin sheet 30 is also interposed between the respective concave portions and the respective convex portions and between the seal receiving seat 42d and the concave portion 37, so that the convex portions 38a are formed in the concave portions 42b and the convex portions are formed in the concave portions 42c. The concave portions 37 are bonded to the seal receiving seats 42d. The seal receiving seat 42d adhered to the recess 37 in this manner becomes a seating / sealing portion of the annular seal 40 that is disposed on the separator 41 side and surrounds each of the supply / discharge holes.

  The separator 41 and the separator 42 are both titanium plates as described above, and are fuel cell separators made of a base material containing titanium in the present invention, and the arithmetic surface of the separator surface on the adhesive surface side with the resin sheet 30. The roughness Ra is 0.2 μm or less, and the crystal grain size on the separator surface is 20 to 50 μm. Such separator surface properties can be defined by appropriately adjusting the annealing conditions when annealing a titanium plate rolled using pure titanium. Therefore, in the present embodiment, first, the annealing conditions are defined so that the above properties are obtained on the separator surface on the adhesion surface side with the resin sheet 30, and a titanium plate having a thickness of 0.1 to 0.15 mm is annealed. The treated titanium plate thus obtained was subjected to a die press, and the separator 41 and the separator 42 were produced. At the time of die pressing, the separator 41 is formed with the in-cell air flow path 41a and the gas / cooling water supply / discharge holes described above, and the separator 42 has the in-cell fuel gas flow path 42a, the recess 42b, the recess 42c, the seal receiving seat 42d, and the gas / cooling water supply / discharge holes described above are formed.

  Next, a deterioration test of the adhesion state between the resin sheet 30 and the separators 41 and 42 in the fuel cell 10 of the present embodiment will be described. FIG. 3 is an explanatory view schematically showing the state of adhesion of a test piece subjected to a deterioration test. In the illustrated degradation test sample SP, the first test piece 1S and the second test piece 2S are adhesives (EPDM or thermoplastic) that constitute the surface layers 30a and 30b of the resin sheet 30 in the fuel cell 10 of the present embodiment. (Polypropylene) is used for bonding. The deterioration test sample SP is a test piece assuming adhesion between the resin sheet 30 and the separators 41 and 42 in the fuel cell 10 of the present embodiment, and the first test piece 1S is the resin sheet 30, specifically the core portion. It is the plate which consists of the same thermoplastic resin as 30c. The second test piece 2S is a plate obtained by die cutting or the like from a titanium plate having a thickness of 0.1 to 0.15 mm annealed to have different surface properties. And after apply | coating said adhesive agent to the 1st test piece 1S and joining the 2nd test piece 2S, both tests were performed through the heating state for 1 minute at 150 degreeC, and the cooling for 1 minute at 120 degreeC. The pieces were bonded and fixed to obtain a deterioration test sample SP. This deterioration test sample SP was immersed in pure water, heated in a heating furnace maintained at 120 ° C. for 500 hours, and subjected to a later-described tensile test after natural cooling curing. The heating for a long time of 500 hours at 120 ° C. indicates that the adhesion state of both test pieces in the deterioration test sample SP, and further the aging state of the adhesion state of the resin sheet 30 and the separators 41 and 42 in the fuel cell 10 of the present embodiment. This is a deterioration test that assumes changes (aging over time).

  FIG. 4 is an explanatory view for displaying a list of sample types, surface properties, and test results. As shown in the figure, the sample types are the embodiment products 1-2 assuming the adhesion between the resin sheet 30 and the separators 41 and 42 in the fuel cell 10 of the present embodiment, and the comparative example in which the surface properties are different from the embodiment products. It is goods 1-2.

  The second test piece 2S in the deterioration test sample SP assuming the embodiment products 1 and 2 and the comparative products 1 and 2 is a titanium plate rolled to a thickness of 0.1 to 0.15 mm using pure titanium. Is formed using existing annealing equipment capable of annealing. In the second test piece 2S assuming the embodiment product 1 and the second test piece 2S assuming the embodiment product 2, the annealing temperature and pressure during continuous annealing in the annealing treatment that defines the surface properties of the titanium plate. The second test piece 2S assuming the embodiment product 1 has an arithmetic surface roughness Ra of 0.08 to 0.11 μm and a surface crystal grain size of 20 to 30 μm (continuous). Annealing I). The second test piece 2S assuming the embodiment product 2 has a surface arithmetic surface roughness Ra of 0.07 to 0.08 μm and a surface crystal grain size of 20 to 50 μm (continuous annealing II). In the 2nd test piece 2S which assumed the comparative example goods 1 and the 2nd test piece 2S which assumed the comparative example goods 2, in the annealing treatment which prescribes | regulates the surface property of a titanium plate, a batch annealing treatment is given, and a comparative example goods The second test piece 2S assuming 1 has a surface arithmetic surface roughness Ra of 0.13 to 0.16 μm and a surface crystal grain size of 5 to 12 μm (batch annealing III). The second test piece 2S assuming the comparative example product 2 was subjected to surface pickling treatment after batch annealing, the surface arithmetic surface roughness Ra was 0.31 to 0.36 μm, and the surface crystal grains The diameter is 5 to 12 μm (batch annealing + pickling IV).

  The deterioration test sample SP of FIG. 3 for each sample type in which each of the second test pieces 2S described above is bonded to the first test piece 1S is pulled with a tensile tester and is broken with an adhesive layer. And the shear strength at the time of an adhesive bond layer fracture | rupture was measured with the tension test machine, and the interface peeling area of the adhesive agent was measured. As shown in FIG. 3, the interfacial peel area is obtained by observing the surface of an adhesive region (10 mm × 10 mm) of the second test piece 2S separated from the first test piece 1S with an optical microscope or an electronic microscope. Calculated | required the area of the interface peeling part peeled from the surface (adhesive interface) of the 2nd test piece 2S, and calculated | required by dividing the said area by the adhesion area | region area. These results are shown in FIG. The fact that the interfacial peel area is 0% means that the separation of the first test piece 1S and the second test piece 2S does not occur when the adhesive peels off from the interface, but the adhesive itself breaks. This means that as the interfacial peel area increases, the adhesion between the adhesive and the surface of the second test piece 2S (adhesive interface) becomes weaker. In view of the bonding state between the resin sheet 30 and the separators 41 and 42 in the fuel cell 10, the sealing performance of the both can be reduced due to bonding.

  FIG. 5 is a graph showing the relationship between the interfacial peel area obtained by the deterioration test and the shear strength, and FIG. 6 shows the arithmetic average roughness Ra of the surface of the second test piece 2S and the interfacial peel area obtained by the deterioration test. 7 is a graph showing the relationship between the arithmetic mean roughness Ra of the surface of the second test piece 2S and the shear strength obtained in the deterioration test, and FIG. 8 is a graph showing the second test piece. FIG. 9 is a graph showing the relationship between the crystal grain size of the surface of 2S and the interfacial peel area obtained by the deterioration test. FIG. 9 shows the crystal grain size of the surface of the second test piece 2S and the shear strength obtained by the deterioration test. It is a graph which shows the relationship.

  From the relationship between the interfacial peel area and the shear strength shown in FIG. 5, a high shear strength can be obtained when the interfacial peel area is 50% or less, whereas when the interfacial peel area exceeds 50%, the shear strength increases. It turned out to be reduced. Thereby, it can be said that it is preferable that an interface peeling area is 50% or less.

  From the relationship between the arithmetic average roughness Ra and the interfacial delamination area shown in FIG. 6, when the arithmetic average roughness Ra is 0.2 μm or less, the interfacial delamination area increases only to about 50%, whereas the arithmetic average roughness It has been found that when the thickness Ra exceeds 0.2 μm, the interfacial peel area greatly exceeds 50%. From FIG. 5, it has been found that when the interfacial debonding area exceeds 50%, the shear strength is greatly reduced. Therefore, by considering the relationship between the arithmetic average roughness Ra and the interfacial debonding area shown in FIG. It can be said that the arithmetic average roughness Ra is preferably 0.2 μm or less.

  From the relationship between the arithmetic average roughness Ra and the shear strength shown in FIG. 7, when the arithmetic average roughness Ra is 0.2 μm or less, a high shear strength is obtained, whereas the arithmetic average roughness Ra is 0.2 μm. It has been found that the shear strength is greatly reduced when exceeding. Thereby, it can be said that arithmetic mean roughness Ra is preferably 0.2 μm or less.

  From the relationship between the crystal grain size shown in FIG. 8 and the interfacial peel area, the crystal grain size is more than about 50% when the crystal grain size is in the range of 20 to 50 μm, whereas the crystal grain size is more than 20 μm. If it is small, the interfacial debonding area varies greatly, and it has been found that this is undesirable from the viewpoint of reducing the interfacial debonding area. From FIG. 5, it has been found that when the interfacial debonding area exceeds 50%, the shear strength is greatly reduced. Therefore, the relationship between the crystal grain size and the interfacial debonding area shown in FIG. The particle diameter is preferably in the range of 20 to 50 μm, and it can be said that it may be in a narrow range of 20 to 40 μm.

  From the relationship between the crystal grain size and the shear strength shown in FIG. 9, when the crystal grain size is in the range of 20 to 50 μm, a high shear strength is obtained, whereas when the crystal grain size is smaller than 20 μm, the shear strength is obtained. As a result, it was found that this was not desirable in terms of securing shear strength. Accordingly, the crystal grain size is preferably in the range of 20 to 50 μm, and it can be said that the crystal grain size may be in a narrow range of 20 to 40 μm.

  When comparing the results shown in FIGS. 5 to 9 with the sample types shown in FIG. 4, the deterioration test samples SP assuming the embodiment products 1 and 2 are all arithmetic surface roughnesses of the surface of the second test piece 2S. Since the surface roughness Ra is 0.2 μm or less and the surface crystal grain size is 20 to 50 μm, even after a deterioration test in which heating is performed at 120 ° C. for 500 hours, interfacial peeling of the adhesive is suppressed and shearing is performed. Strength can be maintained. On the other hand, the deterioration test sample SP assuming the comparative example products 1 and 2 has the arithmetic surface roughness Ra of the surface of the second test piece 2S exceeding 0.2 μm, or the crystal grain size of the surface is more than 20 μm. Because of the small size or the arithmetic surface roughness Ra exceeds 0.2 μm and the crystal grain size of the surface is also smaller than 20 μm, the adhesive is subjected to a deterioration test heated at 120 ° C. for 500 hours. The interfacial peeling increases and the shear strength decreases.

  As described above, in the fuel cell 10 constituting the fuel cell 100 of the present embodiment, the separators 41 and 42 have an arithmetic surface roughness Ra of 0.2 μm or less and a crystal grain size of 20 on the adhesion side surface of the separator. A resin sheet is formed by using an adhesive such as EPDM or thermoplastic polypropylene, which is formed from a titanium plate within a range of ˜50 μm, and which can exhibit an adhesive function to the core portion 30c of the resin sheet 30 (see FIG. 2). Glued and fixed to 30. And according to the fuel cell 10 which comprises the fuel cell 100 of this embodiment, adhesive agent is prescribed | regulated by prescribing | regulating arithmetic surface roughness Ra and crystal grain diameter of the adhesion side surface of the separators 41 and 42 as mentioned above. By suppressing deterioration with time of the sealing performance between the separators 41 and 42 and the resin sheet 30 expressed by the above, it is possible to prolong the service life.

  The fuel cell 10 constituting the fuel cell 100 of the present embodiment is the same as the conventional existing configuration in the cell configuration. Therefore, according to this embodiment, by defining the arithmetic surface roughness Ra and the crystal grain size of the adhesion side surfaces of the separators 41 and 42 as described above, the aging deterioration of the sealing property is suppressed and the service life is long. It is possible to easily manufacture the fuel cell 10 that has been converted into a fuel cell, and thus the fuel cell 10.

  The present invention is not limited to the above-described embodiment, and can be realized with various configurations without departing from the spirit of the present invention. For example, the technical features of the embodiments corresponding to the technical features in each embodiment described in the summary section of the invention are intended to solve part or all of the above-described problems, or part of the above-described effects. Or, in order to achieve the whole, it is possible to replace or combine as appropriate. Further, if the technical feature is not described as essential in the present specification, it can be deleted as appropriate.

  In the above-described embodiment, in defining the arithmetic surface roughness Ra and the crystal grain size of the adhesion side surfaces of the separators 41 and 42 as described above, the annealing conditions during the annealing treatment of the titanium plate are appropriately adjusted. When the arithmetic surface roughness Ra exceeds 0.2 μm, the arithmetic surface roughness Ra can be adjusted to 0.2 μm or less by performing surface polishing using a polishing liquid and an abrasive. Good.

  In the above-described embodiment, the membrane electrode assembly 20 is held by the resin sheet 30 with the cathode side gas diffusion layer 24 and the anode side gas diffusion layer 25 interposed therebetween, and the separators 41 and 42 are bonded to the resin sheet 30. The separators 41 and 42 may be bonded to the resin sheet 30 that holds the membrane electrode assembly 20 without using the gas diffusion layer.

DESCRIPTION OF SYMBOLS 10 ... Fuel cell 20 ... Membrane electrode assembly 21 ... Electrolyte membrane 22 ... Cathode 23 ... Anode 24 ... Cathode side gas diffusion layer 25 ... Anode side gas diffusion layer 26 ... MEGA
DESCRIPTION OF SYMBOLS 30 ... Resin sheet 30a ... Surface layer part 30b ... Surface layer part 30c ... Core part 31 ... Opening region 32 ... Step part 33 ... Frame body part 34a ... Supply hole 34b ... Discharge hole 35a ... Supply hole 35b ... Discharge hole 36a ... Supply hole 36b ... Discharge hole 37 ... Concave part 38a, 38b ... Convex part 40 ... Annular seal 41 ... Separator 41a ... Intra-cell air flow path 42 ... Separator 42a ... Intra-cell fuel gas flow path 42b, 42c ... Concave part 42d ... Seal receiving seat 100 ... Fuel Battery SP ... Degradation test sample 1S ... First test piece 2S ... Second test piece

Claims (1)

A separator for a fuel cell used by adhering to a seal member that holds a membrane electrode assembly in which an electrode catalyst layer is bonded to both membrane surfaces of an electrolyte membrane,
Or titanium plates composed of titanium down Rannahli, arithmetic surface roughness Ra of the separator surface is a 0.2μm or less,
A separator for a fuel cell, wherein the separator has a crystal grain size of 20 to 50 μm.

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