JP2017091825A - Fuel battery stack and manufacturing method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel battery stack and a manufacturing method for the same that can efficiently manufacture a fuel battery stack and avoid leakage of reaction gas from the gap between an electrolytic film and a separator.SOLUTION: A clamped portion 50a in an outer edge portion 20a which is exposed from a cathode electrode 16 and an anode electrode 18 in an electrolyte membrane 20 constituting a first unit cell 14a, and is directly camped between the tip of a convex portion of a first separator 24 and the tip of a convex portion of a second separator 26 and directly coupled thereto. Likewise, the clamped portion 50b in an outer edge portion 20b of the electrolyte membrane 20 constituting a second unit cell 14b is clamped between the tip of a convex portion of the second separator 26 and the tip of a convex portion of a third separator 28. In the separators 24, 26, and 28, a portion bonded to the electrolyte membrane 20 is a hydrophilic portion 42 having a hydrophilic group.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fuel cell stack configured as a stacked body by stacking a plurality of unit cells, and a manufacturing method thereof.

  The fuel cell includes a unit cell in which an electrolyte / electrode structure having an electrolyte membrane (for example, a solid polymer electrolyte membrane) sandwiched between a cathode electrode and an anode electrode is interposed between a pair of separators. A plurality of unit cells are stacked to form a fuel cell stack. Here, in the fuel cell stack, an oxidant gas is supplied to the cathode electrode, while a fuel gas is supplied to the anode electrode. In order to prevent these reaction gases from leaking outside, a gasket is incorporated at the outer edge of the electrolyte / electrode structure. Furthermore, the electrolyte / electrode structure and the gasket are joined together via an adhesive, thereby sealing.

  Patent Document 1 describes that an outer edge portion of an electrolyte membrane and a separator are joined with a sheet-like double-sided adhesive, and sealing is thereby performed. That is, in this case, the electrolyte membrane has a larger area than the cathode electrode and the anode electrode, and the outer edge portion of the electrolyte membrane is exposed from the cathode electrode and the anode electrode. Then, a sheet-like double-sided adhesive is interposed between the exposed outer edge portion and the separator, and in this state, the outer edge portion is sandwiched between the separators.

Japanese Patent Laid-Open No. 9-289029

  As the adhesive, a thermosetting resin is usually employed. However, in this case, there is a disadvantage that the tact time is long. On the other hand, when a thermoplastic resin is used as an adhesive, the tact time can be shortened, but there is a concern that the fuel cell stack may be softened. When such a situation occurs, the softened adhesive enters the reaction gas flow path, which causes a pressure loss to increase.

  The present invention has been made to solve the above-mentioned problems, and it is possible to reduce the tact time, and it is possible to avoid an increase in pressure loss, and further, a reactive gas leaks during operation. An object of the present invention is to provide a fuel cell stack and a method for manufacturing the same that can eliminate the concern.

In order to achieve the above object, the present invention comprises a unit cell in which an electrolyte / electrode structure having an electrolyte membrane sandwiched between an anode electrode and a cathode electrode is interposed between a pair of separators. In the fuel cell stack configured by stacking,
The electrolyte membrane has a larger area than the anode electrode and the cathode electrode, and the outer edge portion is exposed from the anode electrode and the cathode electrode,
The outer edge portion of the electrolyte membrane exposed from the anode electrode and the cathode electrode is directly joined to a hydrophilic portion showing hydrophilicity of the convex portion of the separator.

  That is, in the present invention, the outer edge portion of the electrolyte membrane is directly joined to the separator without interposing an adhesive. For this reason, the process of apply | coating an adhesive agent and the process of hardening this adhesive agent become unnecessary. Accordingly, the tact time until a unit cell is obtained can be shortened. Therefore, it is possible to improve the production efficiency of the fuel cell stack in which unit cells are stacked.

  In addition, since it is not necessary to use an adhesive made of a thermoplastic resin, it is possible to avoid softening between the outer edge portion of the electrolyte membrane and the separator during operation of the fuel cell stack. For this reason, the softened adhesive does not enter the reaction gas flow path, and the pressure loss does not increase due to this. In addition, it is possible to eliminate the concern that the reaction gas leaks from between the outer edge of the electrolyte membrane and the separator.

The present invention also provides a fuel cell stack in which a fuel cell stack is obtained by laminating a plurality of unit cells in which an electrolyte / electrode structure sandwiching an electrolyte membrane between an anode electrode and a cathode electrode is interposed between a pair of separators. In the method
The area of the electrolyte membrane is set to be larger than that of the anode electrode and the cathode electrode, and the electrolyte / electrode structure is prepared so that the outer edge of the electrolyte membrane is exposed from the anode electrode and the cathode electrode. Process,
Forming a hydrophilic portion by applying a hydrophilic surface treatment to at least the convex portion of the separator;
Directly bonding the outer edge portion of the electrolyte membrane exposed from the anode electrode and the cathode electrode to the hydrophilic portion;
It is characterized by having.

  By performing such an operation, the outer edge portion of the electrolyte membrane can be directly joined to the hydrophilic portion of the separator. Accordingly, it is possible to improve the production efficiency of the fuel cell stack in which the unit cells are stacked, and to eliminate the concern that the reaction gas leaks from between the outer edge portion of the electrolyte membrane and the separator during operation of the fuel cell stack. The

  The joining site in the separator is a hydrophilic site. A hydrophilic part shows hydrophilicity, for example, when a hydrophilic group exists. Examples of this type of hydrophilic group include a hydroxyl group or a carboxyl group. In order to provide a hydroxyl group or a carboxyl group, the surface of the separator may be irradiated with either ultraviolet rays or plasma.

  Further, the electrolyte membrane preferably has a hydrophilic group on the surface thereof. In this case, the hydrophilic group and the hydrophilic group at the hydrophilic portion of the separator are bonded through, for example, a hydrogen bond. For this reason, since the bonding force between the separator and the electrolyte membrane is increased, it is possible to more effectively avoid leakage of the reaction gas.

  According to the present invention, the outer edge portion of the electrolyte membrane exposed from the anode electrode and the cathode electrode is directly joined to the hydrophilic portion provided in the separator. For this reason, it is not necessary to use an adhesive, and the tact time until the fuel cell stack is obtained is shortened.

  Moreover, since an adhesive made of a thermoplastic resin is not used, it is possible to avoid softening of the joint between the outer edge of the electrolyte membrane and the separator during operation of the fuel cell stack. For this reason, it is avoided that the pressure loss of the reaction gas channel increases, and the concern that the reaction gas leaks from between the outer edge portion of the electrolyte membrane and the separator is eliminated.

It is principal part sectional drawing cut | disconnected along the direction orthogonal to the distribution direction of the reactive gas of the fuel cell stack which concerns on this Embodiment. It is a schematic front view of the 1st separator which comprises the fuel cell stack of FIG. It is a principal part schematic perspective view of the press apparatus for joining the outer edge part of an electrolyte membrane, and a separator. It is a principal part longitudinal cross-sectional view which shows the state which has joined the outer edge part of the electrolyte membrane, and the separator. It is a principal part schematic perspective view of the press apparatus which concerns on another form.

  Hereinafter, a fuel cell stack according to the present invention will be described in detail with reference to the accompanying drawings by giving preferred embodiments in relation to the manufacturing method thereof.

  FIG. 1 is a cross-sectional view of a principal part of a fuel cell stack 10 according to the present embodiment, cut along a direction orthogonal to the flow direction of oxidant gas and fuel gas (reactive gas). The fuel cell stack 10 is configured by stacking a plurality of cell units 12.

  One cell unit 12 includes a first unit cell 14a and a second unit cell 14b. The first unit cell 14a includes an electrolyte / electrode structure 22 having an electrolyte membrane 20 sandwiched between a cathode electrode 16 and an anode electrode 18, and a first separator 24 sandwiching the electrolyte / electrode structure 22. And the second separator 26. On the other hand, the second unit cell 14 b is configured by sandwiching the electrolyte / electrode structure 22 between the second separator 26 and the third separator 28. That is, the second separator 26 is a component of the first unit cell 14a and a component of the second unit cell 14b.

  Each of the cathode electrode 16 and the anode electrode 18 has an electrode catalyst layer facing the electrolyte membrane 20 side, and a gas diffusion layer joined to the electrode catalyst layer. Since the configurations of the cathode electrode 16 and the anode electrode 18 are known, illustration and detailed description thereof are omitted here.

  The electrolyte membrane 20 is made of a solid polymer (resin) capable of conducting protons. Examples of such a resin include Nafion (trade name of DuPont) having a sulfonic acid group. As is well known, the sulfonic acid group is a hydrophilic group. Alternatively, it may be composed of a hydrocarbon compound.

  The electrolyte membrane 20 is set to have a larger area than the cathode electrode 16 and the anode electrode 18. For this reason, the outer edge portion of the electrolyte membrane 20 is exposed from the cathode electrode 16 and the anode electrode 18.

  FIG. 2 is a front view of the first separator 24. In the upper left corner of the first separator 24, a first gas inlet passage 30 for allowing the oxidant gas to flow is provided. On the other hand, a first gas outlet passage 32 for circulating used oxidant gas is provided at the lower right corner, which is the diagonal position. Similarly, a second gas inlet passage 34 for allowing the fuel gas to pass therethrough is provided at the upper right corner, and a second gas inlet passage 34 for allowing the spent fuel gas to pass therethrough is located at the diagonally lower left corner. A two gas outlet passage 36 is provided. The first separator 24 is further provided with a refrigerant inlet passage 38 between the first gas inlet passage 30 and the second gas outlet passage 36, and between the second gas inlet passage 34 and the first gas outlet passage 32. Is provided with a refrigerant outlet passage 40.

  In addition, the phantom line in FIG. 2 shows the site | part to which the electrolyte membrane 20 is joined by hydrophilizing surface treatment. Hereinafter, this part will be referred to as a “hydrophilic part”, and its reference numeral will be 42.

  In this case, the hydrophilic portion 42 has a hydrophilic group. Representative examples of the hydrophilic group include a hydroxyl group (—OH group) and a carboxyl group (—COOH group). As will be described later, this type of hydrophilic group is provided by ultraviolet irradiation or plasma irradiation.

  Also in the second separator 26 and the third separator 28, the first gas inlet passage 30, the first gas outlet passage 32, the second gas inlet passage 34, the second gas outlet passage 36, the refrigerant inlet at the same position as the first separator 24. A passage 38 and a refrigerant outlet passage 40 are provided.

  Then, on the surface of the first separator 24 facing the cathode electrode 16, a wave-shaped first passage forming portion 44 in which peaks and valleys are alternately formed to supply / discharge the oxidant gas to / from the cathode electrode 16. Is extended. As shown in FIG. 1, the flat top surface of the valley portion of the first passage forming portion 44 is separated from the cathode electrode 16 to form a hollow portion. The oxidant gas flows through this hollow portion. Note that the flat top surface of the peak portion is in contact with the cathode electrode 16.

  The second separator 26 is also provided with a wavy second passage forming portion 46 in which peaks and valleys are alternately formed. The flat top surface of the valley portion of the second passage forming portion 46 is in contact with the anode electrode 18, and the flat top surface of the peak portion is in contact with the cathode electrode 16 of the second unit cell 14b. Accordingly, a hollow portion is formed between the peak portion and the anode electrode 18 and between the valley portion and the cathode electrode 16 of the second unit cell 14b. Fuel gas flows through the former hollow part, and oxidant gas flows through the latter hollow part.

  Further, the third separator 28 is also provided with a wavy third passage forming portion 48 in which peaks and valleys are alternately formed. The flat top surface of the valley portion of the third passage forming portion 48 contacts the anode electrode 18 of the second unit cell 14 b, and the flat top surface of the peak portion is the first unit cell 14 a constituting another cell unit 12. The first separator 24 comes into contact with the top surface of the valley. The fuel gas flows in the hollow portion formed between the peak portion and the anode electrode 18.

  On the other hand, a relatively large volume hollow portion is formed between the valley portion of the third separator 28 and the peak portion of the first separator 24 of the first unit cell 14a. A cooling medium flows through the hollow portion.

  The first separator 24, the second separator 26, and the third separator 28 are all made of stainless steel such as SUS304 or SUS316, which is an iron-based metal material. The material of the first separator 24, the second separator 26, and the third separator 28 may be another metal material, such as a titanium-based metal, or a carbon material.

  As shown in FIG. 1, the outer edge portion 20 a of the electrolyte membrane 20 of the first unit cell 14 a exposed from the cathode electrode 16 and the anode electrode 18 has a convex tip end of the first separator 24 and a convex portion of the second separator 26. It is sandwiched between the tips of the parts, that is, between the hydrophilic portions 42, 42. Further, the outer edge portion 20b of the electrolyte membrane 20 of the second unit cell 14b exposed from the cathode electrode 16 and the anode electrode 18 is between the convex tip end of the second separator 26 and the convex tip end of the third separator 28, that is, It is sandwiched between the hydrophilic portions 42 and 42.

  In a cell unit 12, the sandwiched portion 50a of the electrolyte membrane 20 of the first unit cell 14a is closer to the cathode electrode 16 and the anode electrode 18 than the sandwiched portion 50b of the electrolyte membrane 20 of the second unit cell 14b. . On the other hand, in another cell unit 12 adjacent to the cell unit 12, contrary to the above, the sandwiched portion 50a of the electrolyte membrane 20 of the first unit cell 14a is formed on the electrolyte membrane 20 of the second unit cell 14b. It is separated from the cathode electrode 16 and the anode electrode 18 as compared with the sandwiched portion 50b.

  The sandwiched portions 50 a and 50 b (outer edge portions 20 a and 20 b) of the electrolyte membranes 20 and 20 are directly bonded to the hydrophilic portions 42 of the first separator 24, the second separator 26, and the third separator 28. That is, no adhesive or the like is interposed between the sandwiched portions 50a and 50b and the first separator 24, the second separator 26, and the third separator 28. And by this joining, the sealing part 50a, 50b (electrolyte membrane 20) and each hydrophilic part 42 in the 1st separator 24, the 2nd separator 26, and the 3rd separator 28 are sealed.

  As described above, the hydrophilic portion 42 has a hydrophilic group such as a hydroxyl group or a carboxyl group. On the other hand, the electrolyte membrane 20 is made of, for example, a resin having a hydrophilic group such as a sulfonic acid group. A chemical bond such as a hydrogen bond is generated between these hydrophilic groups. As a result, the sandwiched portions 50a and 50b of the electrolyte membranes 20 and 20 are joined to the first separator 24, the second separator 26, and the third separator 28 without interposing an adhesive.

  The third separator 28 of the second unit cell 14 b and the first separator 24 of the first unit cell 14 a constituting another cell unit 12 are sealed with a sealing material 52. Or you may make it join the 3rd separator 28 and the 1st separator 24 directly by welding etc., without using the sealing material 52. FIG.

  Next, a method for manufacturing the fuel cell stack 10 will be described.

  The first separator 24 is obtained as a molded product by, for example, press working for punching a metal plate made of stainless steel as described above. The first separator 24 is subjected to a hydrophilic surface treatment. As a specific method for hydrophilizing surface treatment, ultraviolet irradiation may be mentioned.

  In the present embodiment, hydrophilic groups are provided at predetermined locations indicated by phantom lines in FIG. For this purpose, the first separator 24 is masked except for the portion where the hydrophilic portion 42 is formed. Next, the first separator 24 in this state is introduced into an ultraviolet irradiation device and irradiated with ultraviolet rays. As ultraviolet rays, vacuum ultraviolet rays having an extremely short wavelength are suitable.

  Hydroxyl groups, carboxyl groups, and the like, which are hydrophilic groups, are generated at the site irradiated with ultraviolet rays. That is, the part irradiated with ultraviolet rays becomes the hydrophilic part 42.

Plasma irradiation may be performed instead of ultraviolet irradiation. An apparatus for performing this irradiation may be an atmospheric plasma apparatus or an O ₂ plasma apparatus. Also in this case, a hydroxyl group, a carboxyl group, or the like is generated at a site irradiated with plasma as in the ultraviolet irradiation. That is, the hydrophilic part 42 is formed.

  Similarly, the hydrophilic portion 42 is provided for the second separator 26 and the third separator 28. Thereby, the 1st separator 24, the 2nd separator 26, and the 3rd separator 28 which have the hydrophilic part 42 are obtained.

  Meanwhile, an electrolyte / electrode structure 22 is produced. That is, the resin material is cut to have a larger area than the gas diffusion layers of the cathode electrode 16 and the anode electrode 18 to obtain the electrolyte membrane 20. If necessary, the electrolyte membrane 20 may be subjected to a hydrophilic surface treatment. The hydrophilic surface treatment can be performed by irradiating with ultraviolet rays or plasma in the same manner as described above. In addition, when the electrolyte membrane 20 is a polymer having a hydrophilic group (for example, Nafion or the like), it is not particularly necessary to perform the hydrophilization surface treatment, but it may be performed.

  Next, for example, after the electrode catalyst layer is transferred to both surfaces of the electrolyte membrane 20 by a decal method, the gas diffusion layer is bonded to the electrode catalyst layer. As a result, an electrolyte / electrode structure 22 in which the outer edge portion of the electrolyte membrane 20 is exposed from the cathode electrode 16 and the anode electrode 18 is obtained.

  The first separator 24, the electrolyte / electrode structure 22, the second separator 26, the electrolyte / electrode structure 22, and the third separator 28 obtained as described above are laminated to assemble a laminate 60, for example, a belt conveyor (Not shown) is conveyed to the pressing device 62 shown in FIG. Of course, you may make it assemble the laminated body 60 in the middle of conveying to the press apparatus 62. FIG. At this time, the outer edge portion of the electrolyte membrane 20 is in contact with the hydrophilic portion 42 of the first separator 24, the second separator 26, and the third separator 28.

  Here, the pressing device 62 has a lower mold 64 and an upper mold 66. The lower mold 64 and the upper mold 66 are formed with protruding protrusions 68 and 70 that press the back surface of the hydrophilic portion 42, respectively. Further, the lower mold 64 and the upper mold 66 are displaced in a direction approaching or separating from each other under the action of a lifting mechanism (not shown).

  When the laminated body 60 is positioned between the lower mold 64 and the upper mold 66, the lower mold 64 and the upper mold 66 are displaced so as to approach each other. Therefore, as shown in a partially enlarged view in FIG. 4, the pressing convex portions 68 and 70 abut against the back surface of the hydrophilic portion 42, and the pressing convex portions 68 and 70 further connect the hydrophilic portion 42 to the outer edge portion of the electrolyte membrane 20. Press toward 20a. Accordingly, the hydrophilic portion 42 is pressed against the outer edge portion 20a (the sandwiched portion 50a) of the electrolyte membrane 20.

  The position where the outer edge portion 20a (the sandwiched portion 50a) of the electrolyte membrane 20 constituting the first unit cell 14a is sandwiched between the convex portion tip of the first separator 24 and the convex portion tip of the second separator 26, and the second unit cell 14b. The position where the outer edge portion 20b (the sandwiched portion 50b) of the electrolyte membrane 20 that constitutes the second membrane 26 is sandwiched between the convex portion tip of the second separator 26 and the convex portion tip of the third separator 28 is different from each other. That is, as described above, the sandwiched portion 50a of the first unit cell 14a is closer to (or separated from) the cathode electrode 16 and the anode electrode 18 than the sandwiched portion 50b of the second unit cell 14b. Yes. Therefore, it is possible to press each of the sandwiched parts 50a and 50b together with the first separator 24 and the second separator 26, or together with the second separator 26 and the third separator 28.

  The resin that is the material of the electrolyte membrane 20 has a hydrophilic group as described above. This hydrophilic group and the hydrophilic group of the hydrophilic portion 42 are bonded through, for example, a hydrogen bond. As a result, the outer edge portions 20a and 20b (the sandwiched portions 50a and 50b) of the electrolyte membrane 20 are bonded to the hydrophilic portion 42 even at room temperature. Thereby, the cell unit 12 is obtained.

  Note that the lower mold 64 and the upper mold 66 may be heated. When the sandwiched parts 50a and 50b and the hydrophilic part 42 are bonded through hydrogen bonds, it is desirable that the temperatures of the lower mold 64 and the upper mold 66 be lower than the decomposition temperature of the electrolyte membrane 20.

  As described above, in the present embodiment, the first separator 24, the second separator 26, and the third separator 28 are provided with the hydrophilic portion 42, and the outer edge portion of the electrolyte membrane 20 is directly bonded to the hydrophilic portion 42. I have to. Therefore, it is not necessary to incorporate the electrolyte / electrode structure 22 into the gasket, and it is not necessary to join the electrolyte / electrode structure 22 and the gaskets or separators 24, 26, 28 via an adhesive. Accordingly, the tact time until the cell unit 12 is obtained can be shortened.

  The cell units 12 obtained as described above are stacked via the sealing material 52. Furthermore, an end plate or the like is stacked on the outermost cell unit 12 and a pressing force is applied, whereby the fuel cell stack 10 is obtained. Since the tact time for obtaining the cell unit 12 is shortened as described above, the production efficiency of the fuel cell stack 10 can be improved.

  When the fuel cell stack 10 is operated, an oxidant gas (for example, compressed air) containing oxygen is supplied from the first separator 24, the second separator 26, and the third separator 28 to the first gas inlet passage 30 shown in FIG. And a fuel gas containing hydrogen (for example, hydrogen) is supplied to the second gas inlet passage 34. Further, an appropriate cooling medium such as pure water, ethylene glycol, or oil is supplied to the refrigerant inlet passage 38.

  The fuel gas is introduced into a hollow portion between the anode electrode 18 of the first unit cell 14 a and the peak portion of the second passage forming portion 46 of the second separator 26. Further, it is also introduced into a hollow portion between the anode electrode 18 of the second unit cell 14 b and the peak portion of the third passage forming portion 48 of the third separator 28. The fuel gas introduced into each hollow portion flows in a direction orthogonal to the paper surface of FIG. Thereby, fuel gas is supplied to each anode electrode 18 of the 1st unit cell 14a and the 2nd unit cell 14b.

  At the anode electrode 18, a reaction occurs in which hydrogen in the fuel gas is ionized to generate protons. This proton moves to the cathode electrode 16 by the proton conduction action of the electrolyte membrane 20. Further, the electrons are used as an electrical energy source for energizing an external load electrically connected to the fuel cell stack 10.

  On the other hand, the oxidant gas is introduced into a hollow portion between the cathode electrode 16 of the first unit cell 14 a and the valley portion in the first passage forming portion 44 of the first separator 24. At the same time, it is also introduced into the hollow portion between the cathode electrode 16 of the second unit cell 14 b and the valley portion in the second passage forming portion 46 of the second separator 26. As the oxidant gas introduced into each hollow portion flows in a direction perpendicular to the paper surface of FIG. 1, the fuel gas is supplied to each cathode electrode 16 of the first unit cell 14a and the second unit cell 14b. Note that the flow direction of the oxidant gas is opposite to the flow direction of the fuel gas.

  In the cathode electrode 16, oxygen in the oxidant gas, protons that have moved through the electrolyte membrane 20, and electrons that have reached the cathode electrode 16 by energizing the external load react to generate water. Thus, the fuel cell stack 10 generates electric power as an electrochemical reaction occurs at each anode electrode 18 and each cathode electrode 16.

  Excess fuel gas supplied to the anode electrode 18 is discharged from the second gas outlet passage 36 as spent gas. Further, excess oxidant gas supplied to the cathode electrode 16 is discharged from the first gas outlet passage 32 as spent gas.

  Then, the coolant flows from the refrigerant inlet passage 38 to the valley portion in the third passage formation portion 48 of the third separator 28 of the first unit cell 14a and the first passage formation portion of the first separator 24 of the second unit cell 14b. 44 is introduced into a hollow portion formed by a peak portion. The cooling medium is also circulated in a direction orthogonal to the paper surface of FIG. 1 and discharged from the refrigerant outlet passage 40. The cell unit 12 is cooled by this distribution.

  While the fuel cell stack 10 is generating electricity as described above, the fuel gas and the oxidant gas are prevented from leaking from between the electrolyte membrane 20 and the separators 24, 26, and 28. This is because the electrolyte membrane 20 and the separators 24, 26, and 28 are directly joined as described above.

  In addition, since an adhesive made of a thermoplastic resin is not used, it is possible that the electrolyte membrane 20 and the separators 24, 26, and 28 are softened and the bonding force is reduced as power generation (operation) is continued. Absent. Therefore, the concern that the pressure loss increases due to the adhesive entering the reaction gas flow path (hollow part) is eliminated.

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

  For example, the pressing device 80 shown in FIG. 5 may be used as a device that joins the outer edge portion of the electrolyte membrane 20 and the hydrophilic portion 42. The pressing device 80 includes a lower roller 82 and an upper roller 84 that rotate in synchronization with each other. Pressing convex portions 86 and 88 are formed on the lower roller 82 and the upper roller 84, respectively. Therefore, when the laminate 60 is positioned between the lower roller 82 and the upper roller 84, the sandwiched portion of the electrolyte membrane 20 is pressed together with the separators 24, 26, and 28 by the pressing convex portions 86 and 88. As a result, the sandwiched portion of the electrolyte membrane 20 of the first unit cell 14a is joined to each hydrophilic portion 42 of the first separator 24 and the second separator 26, and the sandwiched portion of the electrolyte membrane 20 of the second unit cell 14b is the second. The separator 26 and the third separator 28 are bonded to the hydrophilic portions 42.

  In addition, after sandwiching the first unit cell 14a between the first separator 24 and the second separator 26 and joining the sandwiched portion of the electrolyte membrane 20 to the hydrophilic portion 42 of the separators 24 and 26, the electrolyte / The electrode structure 22 and the third separator 28 may be stacked, and the sandwiched portion of the electrolyte membrane 20 of the second unit cell 14b may be joined to the hydrophilic portion 42 of the separators 26 and 28.

  The separators 24, 26 and 28 may be made of carbon. Also in this case, the hydrophilic portion 42 can be provided by performing a hydrophilic surface treatment according to the above.

DESCRIPTION OF SYMBOLS 10 ... Fuel cell stack 12 ... Cell unit 14a, 14b ... Unit cell 16 ... Cathode electrode 18 ... Anode electrode 20 ... Electrolyte membrane 20a, 20b ... Outer edge part 22 ... Electrolyte and electrode structure 24, 26, 28 ... Separator 42 ... Hydrophilic Part 50a, 50b ... clamping part 60 ... Laminate 62, 80 ... Pressing device 64 ... Lower mold 66 ... Upper mold 68, 70, 86, 88 ... Pressing convex part 82 ... Lower roller 84 ... Upper roller

Claims (6)

In a fuel cell stack comprising a unit cell in which an electrolyte / electrode structure sandwiching an electrolyte membrane between an anode electrode and a cathode electrode is interposed between a pair of separators, and a plurality of the unit cells are laminated,
The electrolyte membrane has a larger area than the anode electrode and the cathode electrode, and the outer edge portion is exposed from the anode electrode and the cathode electrode,
The fuel cell stack, wherein the outer edge portion of the electrolyte membrane exposed from the anode electrode and the cathode electrode is directly joined to a hydrophilic portion showing hydrophilicity of the convex portion of the separator.   2. The fuel cell stack according to claim 1, wherein a hydroxyl group or a carboxyl group is present in the hydrophilic portion.   3. The fuel cell stack according to claim 1, wherein the electrolyte membrane has a hydrophilic group on a surface thereof. In a method of manufacturing a fuel cell stack, a fuel cell stack is obtained by stacking a plurality of unit cells in which an electrolyte / electrode structure sandwiched between an anode electrode and a cathode electrode is interposed between a pair of separators.
The area of the electrolyte membrane is set to be larger than that of the anode electrode and the cathode electrode, and the electrolyte / electrode structure is prepared so that the outer edge of the electrolyte membrane is exposed from the anode electrode and the cathode electrode. Process,
Forming a hydrophilic portion by applying a hydrophilic surface treatment to at least the convex portion of the separator;
Directly bonding the outer edge portion of the electrolyte membrane exposed from the anode electrode and the cathode electrode to the hydrophilic portion;
A method for manufacturing a fuel cell stack, comprising:   5. The method of manufacturing a fuel cell stack according to claim 4, wherein as the hydrophilization surface treatment, either ultraviolet irradiation or plasma irradiation is performed, and a hydroxyl group or a carboxyl group is provided on the surface of the separator.   6. The method of manufacturing a fuel cell stack according to claim 4 or 5, wherein a material having a hydrophilic group on the surface thereof is selected as the electrolyte membrane.

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