JP6517528B2 - Fuel cell and method of manufacturing the same - Google Patents

Description

  The present invention relates to a fuel cell obtained through a temporary assembly in which an electrolyte membrane / electrode assembly having a resin frame member at its outer peripheral portion and a separator are stacked and temporarily fixed, and a method of manufacturing the same.

  For example, in a polymer electrolyte fuel cell, an electrolyte is provided in which an anode electrode is disposed on one side of a solid polymer electrolyte membrane made of a polymer ion exchange membrane, and a cathode electrode is disposed on the other side of the solid polymer electrolyte membrane. A membrane electrode assembly (MEA) is provided. The electrolyte membrane-electrode assembly constitutes a power generation cell (unit cell) by being sandwiched by the separators. In a fuel cell, several tens to several hundreds of power generation cells are usually stacked and used, for example, as a fuel cell stack for vehicles.

  In such a fuel cell, a so-called internal manifold is often configured to supply the fuel gas and the oxidant gas, which are reaction gases, to the anode electrode and the cathode electrode of each stacked power generation cell. Therefore, in order to ensure the sealing performance of the reaction gas, etc., it is necessary to position and assemble the MEA and the separator accurately.

  By the way, in a fuel cell, in order to reduce the amount of use of a relatively expensive solid polymer electrolyte membrane, thinning of the solid polymer electrolyte membrane has been attempted. At that time, in order to protect the solid polymer electrolyte membrane whose strength is reduced due to thinning, a framed MEA incorporating a resin frame member is adopted. Such a resin frame member is prone to warping. Therefore, it becomes difficult to accurately position and assemble the MEA and the separator.

  Therefore, the present applicant has proposed the fuel cell described in Patent Document 1 in order to accurately and easily position the framed MEA and the separator. The fuel cell is assembled through a structure in which the MEA and the separator are integrated. That is, first, in order to form a structure, the MEA and the separator are accurately positioned and stacked, and in a state where they are in contact with each other, predetermined positions of the resin frame member are heated and melted in spots. Therefore, even if a resin frame member that is particularly susceptible to warpage is used, as described above, the MEA and the separator are welded and integrated, so that the resin frame member is reliably fixed to the separator. You can get the body. By laminating a plurality of such structures, it becomes possible to easily assemble a fuel cell in which the occurrence of mutual displacement between the MEA and the separator is suppressed as much as possible.

JP, 2014-132548, A

  By the way, in order to suppress the occurrence of mutual displacement between the MEA and the separator, it is necessary to maintain the welded state of the resin frame member and the separator in the structure at the time of assembling the fuel cell as described above. On the other hand, if the welded state is maintained at the time of operation of the fuel cell, extra stress is generated between the resin frame member and the separator due to the expansion and contraction of the electrolyte membrane, and the fuel cell is durable. There is a concern to decline. Therefore, in order to avoid the occurrence of such stress, it is necessary to operate the fuel cell in a state in which the resin frame member and the separator are separated.

  That is, when assembling the fuel cell, a temporary assembly can be formed which can maintain the welded state of the resin frame member and the separator, and can separate the welded portion of the resin frame member and the separator during operation of the fuel cell. It is required to obtain a fuel cell through a temporary assembly.

  SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and provides a fuel cell excellent in durability while suppressing occurrence of positional deviation between MEA and separator as much as possible, and a method of manufacturing the same. The purpose is

The present invention is a fuel cell manufacturing method for obtaining a fuel cell through a temporary assembly in which an electrolyte membrane / electrode assembly having a resin frame member at its outer periphery and a metallic separator are laminated and temporarily fixed, Laminating the electrolyte membrane-electrode assembly and the separator, bringing one surface of the resin frame member and the separator into contact with each other to form a contact portion, and from the other surface of the separator The contact portion is heated to melt the resin frame member to form a melt-solidified portion, and the temporary obtained by temporarily fixing the separator and the resin frame member via the melt-solidified portion. Assembling the assembly to obtain the fuel cell, wherein the melt-solidified portion is a substantially rectangular shape having a long side and a short side equal to or less than the long side, and the long side of the short side Is in the range of 1 to 5 mm, and the area is characterized in that it is mm ² or more.

  In the method of manufacturing a fuel cell according to the present invention, as described above, the contact portions where the resin frame member and the separator are brought into contact with each other are heated to form a melt-solidified portion, and integrated by welding to form a temporary assembly. obtain. For this reason, even in the case of using a resin frame member that is particularly susceptible to warpage, the resin frame member can be reliably fixed to the separator.

  In addition, the area of the melt-solidified site is set as described above. As a result, the shear strength of the temporary assembly can be made large enough to maintain the welded state of the MEA and the separator at the time of fuel cell assembly.

  On the other hand, since the short side of the melt-solidified portion is set as described above, it is possible to easily peel off the welding portion of the MEA and the separator in the temporary assembly during operation of the fuel cell. That is, the molten and solidified site is exposed to the vapor of the generated water generated by the electrochemical reaction in the MEA, the vapor supplied with the fuel gas to keep the electrolyte membrane in a wet state, and the like during operation of the fuel cell.

  When the melted and solidified portion is exposed to water vapor, moisture intrudes from the edge to the interface with the separator, and natural peeling progresses inward from the edge of the melted and solidified portion. When the short side is set as described above, water infiltrates into the entire interface between the melt-solidified portion and the separator early, so that the entire melt-solidified portion can be efficiently and easily peeled from the separator. As a result, it is possible to avoid the generation of excessive stress between the resin frame member and the separator as the electrolyte membrane expands and contracts during operation of the fuel cell.

  From the above, it is possible to form a temporary assembly which can maintain the welded state of the resin frame member and the separator at the time of assembly of the fuel cell and can peel away the welded portion of the resin frame member and the separator at the time of operation of the fuel cell. Can. By passing through this temporary assembly, occurrence of positional deviation between the MEA and the separator can be suppressed as much as possible, and a fuel cell excellent in durability can be obtained.

Further, the present invention is a fuel cell obtained by passing through a temporary assembly in which an electrolyte membrane-electrode assembly having a resin frame member at its outer peripheral portion and a metallic separator are laminated and temporarily fixed, and the resin frame The member is formed by melting and solidifying, and it has a melting and solidifying site for temporarily fixing between the resin frame member and the separator at the time of formation of the temporary assembly, and the melting and solidifying site is a long side and the long side It is a substantially rectangular shape having a short side equal to or less than the length, and the short side has a length of 1 to 5 mm and an area of 3 mm ² or more.

  At the time of assembly of the fuel cell, which is a stage prior to the first operation of the fuel cell, the melt solidified portion temporarily fixes the resin frame member and the separator by welding to form a temporary assembly. On the other hand, after the first operation of the fuel cell, the fusion / solidification site is exposed to the water vapor associated with the operation of the fuel cell, etc. to peel off the weld between the resin frame member and the separator, so no temporary assembly is formed. .

  As described above, the short side and the area are set at the melting and solidification site. Since the shear strength of the temporary assembly is adjusted by this, the fuel cell can be assembled in a state in which the welded state of the resin frame member and the separator is maintained. That is, in this case, since the fuel cell can be obtained by accurately positioning the MEA and the separator to form a temporary assembly and laminating the temporary assembly, positional deviation between the MEA and the separator occurs. It can be suppressed as much as possible. In addition, even if a resin frame member that is particularly susceptible to warpage is used, the resin frame member is securely fixed to the separator to form a temporary assembly, so that the MEA and the separator can be accurately positioned. Can.

  On the other hand, when the melted and solidified portion is exposed to water vapor during operation of the fuel cell, the melted and solidified portion is formed into the above-mentioned shape, whereby moisture infiltrates into the entire interface between the melted and solidified portion and the separator. Natural exfoliation proceeds. By this, the entire molten and solidified site can be peeled off from the separator efficiently and easily. Therefore, in the fuel cell of the present invention, it is possible to avoid the occurrence of excessive stress between the resin frame member and the separator accompanying expansion and contraction of the electrolyte membrane during operation.

  From the above, the fuel cell of the present invention can suppress the occurrence of positional deviation between the MEA and the separator as much as possible, and can improve the durability.

In the present invention, a fuel cell is obtained through a temporary assembly in which the short side of the melt-solidified part is in the range of 1 to 5 mm and the area is 3 mm ² or more. By this, at the time of fuel cell assembly, it is possible to sufficiently maintain the welding state between the MEA and the separator which are accurately positioned. On the other hand, during the operation of the fuel cell, the entire melt-solidified portion can be efficiently and easily peeled off from the separator, so excessive stress is generated between the resin frame member and the separator as the electrolyte membrane expands and contracts. It can be avoided to occur.

  Accordingly, it is possible to obtain a fuel cell which is suppressed as much as possible from the positional deviation between the MEA and the separator and which is excellent in the durability.

It is a principal part disassembled perspective explanatory view of a power generation unit which constitutes a fuel cell concerning an embodiment of the present invention. FIG. 2 is a cross-sectional explanatory view taken along line II-II in FIG. It is front explanatory drawing of the 1st separator of FIG. It is front explanatory drawing of the 1st electrolyte membrane and electrode structure of FIG. It is explanatory drawing at the time of welding the said 1st separator and the 1st resin frame member of the said 1st electrolyte membrane electrode structure by a heating apparatus. It is a schematic explanatory drawing of the fusion | melting solidification site | part of FIG. It is a graph which shows the relationship between the area of a melt-solidification site | part, and a shear strength about the temporary assembly which concerns on an Example. It is a graph which shows the relationship of the length of the short side of a fusion | melting solidification site | part and natural peeling time about the temporary assembly which concerns on an Example.

  As shown in FIGS. 1 and 2, the fuel cell 10 according to the present embodiment includes a power generation unit 12. The plurality of power generation units 12 are stacked on one another along a horizontal direction (arrow A direction) or a vertical direction (arrow C direction) to form a stack. This stack is mounted, for example, on a fuel cell electric vehicle (not shown).

  The power generation unit 12 is provided with a first separator 14, a first electrolyte membrane electrode assembly (first MEA) 16 a, a second separator 18, a second electrolyte membrane electrode assembly (second MEA) 16 b and a third separator 20.

  In the following description, the first separator 14, the second separator 18, and the third separator 20 are collectively referred to as a separator. Also, the first MEA 16a and the second MEA 16b are collectively referred to as an electrolyte membrane-electrode assembly (MEA).

  These separators are made of, for example, a steel plate, a stainless steel plate, an aluminum plate, a plated steel plate, or a horizontally elongated metal plate whose surface is subjected to surface treatment for corrosion prevention. The separator has a rectangular flat surface, and is formed into an uneven cross-sectional shape by pressing a metal thin plate into a corrugated shape.

  As shown in FIG. 1, at one end edge of the power generation unit 12 in the longitudinal direction (arrow B direction), an oxidant gas inlet communication hole 22a and a fuel gas outlet communication hole 24b are provided in communication with each other in the arrow A direction. Be Specifically, the oxidant gas inlet communication hole 22a and the fuel gas outlet communication hole 24b are respectively provided at one end of the separator in the longitudinal direction (arrow B direction). The oxidant gas inlet manifold 22a supplies an oxidant gas, for example, an oxygen-containing gas, while the fuel gas outlet manifold 24b discharges a fuel gas, for example, a hydrogen-containing gas.

  The other end edge of the power generation unit 12 in the longitudinal direction (arrow B direction) communicates with each other in the arrow A direction to discharge a fuel gas inlet communication hole 24 a for supplying fuel gas and an oxidant gas. The oxidant gas outlet communication hole 22b is provided.

  A pair of cooling media for supplying a cooling medium to each other in the direction of arrow A at one end on the side of the oxidant gas inlet communication hole 22a at both end edges of the power generation unit 12 in the short direction (arrow C direction) An inlet communication hole 25a is provided. A pair of cooling medium outlet communication holes 25 b for discharging the cooling medium is provided on the other end of the power generation unit 12 in the short side direction of the power generation unit 12 on the fuel gas inlet communication hole 24 a side.

  At one end edge and the other end edge of the power generation unit 12 in the longitudinal direction, knock holes 27a and 27b are formed substantially at the center in the direction of the arrow C, respectively. Positioning between the separators in the power generation unit 12 is performed by inserting resin knock pins (not shown) into the knocking holes 27a and 27b.

  As shown in FIG. 3, on the surface 14a of the first separator 14 facing the first MEA 16a, there is formed a first oxidant gas flow passage 26 communicating with the oxidant gas inlet communication hole 22a and the oxidant gas outlet communication hole 22b. Be done.

  The first oxidant gas flow channel 26 has a plurality of corrugated flow channel grooves (which may be linear flow channel grooves) 26a extending in the arrow B direction. A plurality of inlet embossed portions 28 a and outlet embossed portions 28 b are provided in the vicinity of the inlet and the outlet of the first oxidant gas channel 26, respectively.

  A plurality of inlet connection grooves 30a constituting a bridge portion are formed between the inlet embossed portion 28a and the oxidant gas inlet communication hole 22a. A plurality of outlet connection grooves 30b constituting a bridge portion are formed between the outlet embossed portion 28b and the oxidant gas outlet communication hole 22b.

  As shown in FIG. 1, a coolant flow path 32 communicating with the pair of coolant inlet communication holes 25 a and the pair of coolant outlet communication holes 25 b is formed on the surface 14 b of the first separator 14. The cooling medium channel 32 is formed by overlapping the back surface shape of the first oxidant gas flow channel 26 and the back surface shape of the second fuel gas flow channel 42 described later.

  A first fuel gas passage 34 communicating with the fuel gas inlet communication hole 24a and the fuel gas outlet communication hole 24b is formed on the surface 18a of the second separator 18 facing the first MEA 16a. The first fuel gas flow channel 34 has a plurality of corrugated flow channel grooves (which may be straight flow channel grooves) 34a extending in the arrow B direction.

  In the vicinity of the fuel gas inlet communication hole 24a, a plurality of supply flow channel grooves 36a for connecting the fuel gas inlet communication hole 24a and the first fuel gas flow channel 34 are formed. The plurality of supply channel grooves 36a are covered by a lid 37a which is a bridge. In the vicinity of the fuel gas outlet communication hole 24b, a plurality of discharge flow channel grooves 36b for communicating the fuel gas outlet communication hole 24b with the first fuel gas flow channel 34 are formed. The plurality of discharge flow channel grooves 36 b are covered by a lid 37 b which is a bridge.

  A second oxidant gas flow path 38 communicating with the oxidant gas inlet manifold 22 a and the oxidant gas outlet manifold 22 b is formed on the surface 18 b of the second separator 18 facing the second MEA 16 b. The second oxidizing gas channel 38 has a plurality of corrugated channel grooves (which may be linear channel grooves) extending in the direction of arrow B.

  As shown in FIG. 1, a second fuel gas passage 42 communicating with the fuel gas inlet communication hole 24 a and the fuel gas outlet communication hole 24 b is formed on the surface 20 a of the third separator 20 facing the second MEA 16 b. The second fuel gas flow channel 42 has a plurality of corrugated flow channel grooves (which may be linear flow channel grooves) 42a extending in the arrow B direction.

  In the vicinity of the fuel gas inlet communication hole 24a, a plurality of supply flow channel grooves 44a for connecting the fuel gas inlet communication hole 24a and the second fuel gas flow channel 42 are formed. The plurality of supply channel grooves 44a are covered by a lid 45a which is a bridge. In the vicinity of the fuel gas outlet communication hole 24b, a plurality of discharge flow channel grooves 44b for connecting the fuel gas outlet communication hole 24b and the second fuel gas flow channel 42 are formed. The plurality of discharge flow channel grooves 44b are covered by a lid 45b which is a bridge.

  In the surface 20 b of the third separator 20, a part of the cooling medium channel 32 which is the back surface shape of the second fuel gas channel 42 is formed. The cooling medium channel 32 is integrally provided on the surface 20 b of the third separator 20 by laminating the surface 14 b of the first separator 14 adjacent to the third separator 20.

  A first seal member 46 is integrally formed on the surfaces 14 a and 14 b of the first separator 14 around the outer peripheral edge of the first separator 14. A second seal member 48 is integrally formed on the surfaces 18 a and 18 b of the second separator 18 around the outer peripheral edge of the second separator 18. The third seal member 50 is integrally formed on the surfaces 20 a and 20 b of the third separator 20 around the outer peripheral edge of the third separator 20.

  As the first seal member 46, the second seal member 48 and the third seal member 50, for example, EPDM, NBR, fluororubber, silicone rubber, fluorosilicone rubber, butyl rubber, natural rubber, styrene rubber, chloroprene, acrylic rubber, etc. An elastic sealing material such as a sealing material, a cushioning material, or a packing material is used.

  As shown in FIG. 3, in the surface 14 a of the first separator 14, the first seal member 46 includes the oxidant gas inlet manifold 22 a and the oxidant gas outlet manifold 22 b and the first oxidant gas channel 26. It has a first convex seal portion 46a surrounding the outer periphery. As shown in FIG. 2, the first convex seal portion 46 a abuts on the second seal member 48 of the second separator 18 stacked with the first MEA 16 a interposed therebetween. The first convex seal portion 46 a constitutes an outer seal member positioned and disposed on the outer periphery of a first resin frame member 58 described later.

  Positioning ribs 46 ar are formed integrally with the first seal member 46 on the surface 14 a of the first separator 14. The positioning rib 46 ar has a function of positioning the first MEA 16 a relative to the first separator 14, and is provided as necessary.

  As shown in FIG. 1, the first seal member 46 is a second protrusion surrounding the outer periphery of the cooling medium inlet communication hole 25 a, the cooling medium outlet communication hole 25 b, and the cooling medium channel 32 on the surface 14 b of the first separator 14. Shaped seal portion 46b.

  The second seal member 48 has a first convex seal portion 48 a surrounding the first fuel gas passage 34 on the surface 18 a of the second separator 18. As shown in FIG. 2, the first convex seal portion 48 a constitutes an inner seal member that abuts on the first resin frame member 58 of the first MEA 16 a adjacent to the second separator 18.

  The second seal member 48 has a second convex seal portion 48b surrounding the outer periphery of the oxidant gas inlet manifold 22a and the oxidant gas outlet manifold 22b and the second oxidant gas channel 38 on the surface 18b. As shown in FIG. 2, the second convex seal portion 48 b abuts on the third seal member 50 of the third separator 20 stacked with the second MEA 16 b interposed therebetween. The second convex seal portion 48 b constitutes an outer seal member positioned and disposed on the outer periphery of a second resin frame member 60 described later.

  As shown in FIG. 2, positioning ribs 48 br are formed integrally with the second seal member 48 on the surface 18 b. The positioning rib 48 br has a function of positioning the second MEA 16 b relative to the second separator 18 and is provided as necessary.

  As shown in FIG. 1, the third seal member 50 has a first convex seal portion 50 a surrounding the second fuel gas flow channel 42 on the surface 20 a of the third separator 20. As shown in FIG. 2, the first convex seal portion 50 a constitutes an inner seal member that abuts on the second resin frame member 60 of the second MEA 16 b adjacent to the third separator 20.

  The third seal member 50 is a second convex seal portion (outer seal member) surrounding the outer periphery of the cooling medium inlet communication hole 25a, the cooling medium outlet communication hole 25b, and the cooling medium channel 32 on the surface 20b of the third separator 20 ) 50b.

  As shown in FIG. 2, the MEA includes, for example, a solid polymer electrolyte membrane (electrolyte membrane) 52 in which a thin film of perfluorosulfonic acid is impregnated with water, and a cathode electrode 54 and an anode electrode 56 sandwiching the electrolyte membrane 52. And The cathode electrode 54 constitutes a step-type MEA having a planar dimension (surface dimension) smaller than the planar dimension (surface dimension) of the anode electrode 56 and the electrolyte membrane 52.

  The cathode electrode 54, the anode electrode 56, and the electrolyte membrane 52 may be set to the same plane size, and the anode electrode 56 may be a plane smaller than the plane dimensions of the cathode electrode 54 and the electrolyte membrane 52. It may have dimensions.

  In the cathode electrode 54 and the anode electrode 56, a gas diffusion layer (not shown) made of carbon paper or the like, and porous carbon particles carrying a platinum alloy on the surface are uniformly coated on the surface of the gas diffusion layer. And an electrode catalyst layer (not shown) to be formed. The electrode catalyst layer is formed, for example, on both sides of the electrolyte membrane 52.

  The first MEA 16a is positioned outward of the end of the cathode electrode 54, and a first resin frame member 58 is integrally formed on the outer peripheral edge of the electrolyte membrane 52 by, for example, injection molding. The second resin frame member 60 is integrally formed on the outer peripheral edge portion of the electrolyte membrane 52 by, for example, injection molding or the like.

  The first resin frame member 58 and the second resin frame member 60 may be separately formed and joined to the first MEA 16a and the second MEA 16b with an adhesive or the like. As a resin material which comprises the 1st resin frame member 58 and the 2nd resin frame member 60, engineering plastics, super engineering plastics, such as PES (polyether sulfone), etc. are adopted other than general purpose plastic, for example.

  As shown in FIGS. 1 and 4, the surface of the first resin frame member 58 on the cathode electrode 54 side is located between the oxidant gas inlet communication hole 22 a and the inlet side of the first oxidant gas channel 26. An inlet buffer 62a is provided. In addition, an outlet buffer portion 62b is disposed on the surface of the first resin frame member 58 on the cathode electrode 54 side between the oxidant gas outlet communication hole 22b and the outlet side of the first oxidant gas flow path 26. Provided. The inlet buffer portion 62a and the outlet buffer portion 62b have a plurality of linear convex portions and embossed portions. The buffer units described below are similarly configured.

  An inlet buffer portion 68 a is provided on the surface of the first resin frame member 58 on the anode electrode 56 side, between the fuel gas inlet communication hole 24 a and the first fuel gas flow path 34. Further, an outlet buffer portion 68 b is provided on the surface of the first resin frame member 58 on the side of the anode electrode 56 so as to be located between the fuel gas outlet communication hole 24 b and the first fuel gas passage 34. Notches 70 a and 70 b for passing the knock pin are formed at both ends in the direction of arrow B of the first resin frame member 58.

  In the vicinity of the inlet buffer portion 62a of the first resin frame member 58 and in the vicinity of the outlet buffer portion 62b, a plurality of melt-solidified portions 98a are provided. The melted and solidified portion 98a is formed by melting and solidifying the first resin frame member 58, and the details thereof will be described later.

  As shown in FIG. 1, the second resin frame member 60 provided in the second MEA 16b is located on the cathode electrode 54 side between the oxidant gas inlet manifold 22a and the second oxidant gas channel 38. An inlet buffer 74a is provided. Further, an outlet buffer portion 74b is formed on the surface of the second resin frame member 60 on the cathode electrode 54 side so as to be located between the oxidant gas outlet communication hole 22b and the second oxidant gas flow path 38. .

  An inlet buffer portion 80 a is provided on the surface of the second resin frame member 60 on the anode electrode 56 side, between the fuel gas inlet communication hole 24 a and the second fuel gas passage 42. Further, an outlet buffer portion 80b is provided on the surface of the second resin frame member 60 on the anode electrode 56 side, between the fuel gas outlet communication hole 24b and the second fuel gas channel 42. Notches 81 a and 81 b for passing the knock pin are formed at both ends in the direction of arrow B of the second resin frame member 60.

  In the vicinity of the inlet buffer portion 80a of the second resin frame member 60 and in the vicinity of the outlet buffer portion 80b, a plurality of melt solidified portions 98b described later are provided in the same manner as the melt solidified portion 98a.

  The cooling medium flow path 32 is formed between the first separator 14 constituting one power generation unit 12 and the third separator 20 constituting the other power generation unit 12 by stacking the power generation units 12 with each other. It is formed.

  In the present embodiment, the power generation unit 12 is assembled by stacking the first temporary assembly 82, the second temporary assembly 84, and the third separator 20. The first temporary assembly 82 is configured by laminating the first MEA 16 a and the first separator 14, and when the power generation unit 12 is assembled, they are temporarily fixed to each other by welding. Specifically, in this temporary fixing, the first resin frame member 58 of the first MEA 16a and the heating portion 96a (see FIGS. 2 and 3) of the first separator 14 are formed on the first resin frame member 58. It is formed by welding through the melted and solidified portion 98a.

  The second temporary assembly 84 is configured by stacking the second MEA 16 b and the second separator 18, and when the power generation unit 12 is assembled, the two temporary assemblies 84 are temporarily fixed to each other by welding. Specifically, in this temporary fixing, the second resin frame member 60 of the second MEA 16b and the heated portion 96b (see FIG. 2) of the second separator 18 are melt-solidified in the second resin frame member 60. It is formed by welding through the site 98b.

  That is, when manufacturing the power generation unit 12, first, the first temporary assembly 82 and the second temporary assembly 84 are manufactured. Specifically, in order to obtain the first temporary assembly 82, first, the first MEA 16a and the first separator 14 are laminated, and one surface 58a of the first resin frame member 58 and one surface of the first separator 14 are obtained. The contact portion 14 a is formed to form a contact portion. Then, the heating portion 96 a of the first separator 14 is heated by the heating device 90 shown in FIG. 5 from the other surface 14 b side of the contact portion, and the first resin frame member 58 is melted.

  The heating device 90 includes a base 92 and a heating rod 94 heated by an electric heater. The base 92 has a flat contact surface with the first resin frame member 58. The heating rod 94 preferably has a flat contact surface with the first separator 14, but may have, for example, a smooth R shape at the tip. The surface area of the abutment portion of the base portion 92 is larger than the surface area of the abutment portion of the heating rod 94.

  Note that, instead of the heating device 90, for example, the heating portion 96a of the first separator 14 may be directly heated by various heating devices such as a laser heating device (not shown).

  The first resin frame member 58 is placed on the base portion 92, and the first separator 14 is placed on the first resin frame member 58. The first separator 14 is positioned relative to the first MEA 16 a by the positioning rib 46 ar. It is preferable that the bonding portion of the first separator 14 be subjected to a roughening treatment in advance. This is because the bonding strength can be improved. Further, a flat portion surrounding the first oxidant gas flow path 26 is formed over the entire circumference of the first separator 14. The same applies to the second separator 18.

  Then, the heating rod 94 heated to a predetermined temperature is pressed against the surface 14b of the heating portion 96a with a predetermined pressure. As a result, the first resin frame member 58 is heated via the first separator 14, so that a part of the first resin frame member 58 is melted. Then, the temperature of the heating rod 94 is lowered to solidify the melted portion, and the melted and solidified portion 98 a is formed on the first resin frame member 58.

  As shown in FIG. 3, the heating portions 96 a are provided at a plurality of positions of the first separator 14. As a result, as shown in FIG. 4, melt solidified portions 98 a are provided at a plurality of positions of the first resin frame member 58 corresponding to the above-described heated portions 96 a. The first separator 14 and the first resin frame member 58 are integrated by welding through the melted and solidified portion 98a. As a result, with the first separator 14 and the first MEA 16a correctly positioned relative to each other, an integrated first temporary assembly 82 is obtained.

  On the other hand, in the same manner as described above, the second MEA 16b and the second separator 18 are also stacked on each other, and one surface 60a of the second resin frame member 60 and one surface 18a of the second separator 18 are brought into contact with each other. Form contact sites. Then, the heating portion 96b is heated by the heating device 90 from the side of the other surface 18b of the second separator 18 to melt the second resin frame member 60 among the contact portions. Thereafter, the melted portion is solidified to form a melted and solidified portion 98b.

  Similar to the first separator 14, heating portions 96 b are provided at a plurality of positions of the second separator 18. As a result, melt solidified portions 98 b (see FIG. 1) are provided at a plurality of positions of the second resin frame member 60 corresponding to the heated portions 96 b. The second separator 18 and the second resin frame member 60 are integrated by welding through the melted and solidified portion 98 b. As a result, an integrated second temporary assembly 84 is obtained with the second separator 18 and the second MEA 16 b accurately positioned relative to each other.

  For this reason, even if the first resin frame member 58 and the second resin frame member 60 which are particularly susceptible to warpage are used, the first resin frame member 58 and the second resin frame member 60 respectively correspond to the first separator 14 and the second resin frame member 60. 2 can be fixed to the separator 18 with certainty.

The first temporary assembly 82 and the second temporary assembly 84 formed as described above and the third separator 20 are further stacked using knock pins (not shown) inserted into the knock holes 27a and 27b. Thus, the power generation unit 12 is assembled. At this time, as shown in FIG. 6, the shape of the melt-solidified portions 98a, 98b is substantially rectangular with a long side L1 and a short side L2 extending along the longitudinal direction (arrow B direction) of the separator. The short side L2 is set in the range of 1 to 5 mm, and the area is set to 3 mm ² or more.

  The direction in which the long side L1 extends is not limited to the direction along the longitudinal direction of the separator. On the other hand, the first temporary assembly 82 and the second temporary assembly 84 described above are easily bent along the longitudinal direction when transported. Therefore, it is preferable to make the direction of the long side L1 coincide with the longitudinal direction because peeling due to the bending is less likely to occur.

  Thereby, the shear strength can be set to 15 N or more, and the steam natural peeling time can be set to 120 hours or less for the characteristics of the melt solidified portions 98 a and 98 b. Thus, by adjusting the shear strength, it is possible to sufficiently maintain the welding state of the MEA and the separator at the time of assembly of the power generation unit 12. Therefore, there is an advantage that the positioning in the power generation unit 12 and the positioning of the plurality of power generation units 12 are easily and efficiently performed.

  The fuel cell 10 can be obtained by stacking the power generation units 12 assembled as described above to form a stack. The operation of the fuel cell 10 will be described below.

  First, as shown in FIG. 1, an oxidant gas such as an oxygen-containing gas is supplied to the oxidant gas inlet manifold 22a, and a fuel gas such as a hydrogen-containing gas is supplied to the fuel gas inlet manifold 24a. Furthermore, a cooling medium such as pure water, ethylene glycol, or oil is supplied to the cooling medium inlet communication hole 25a.

  Therefore, a part of the oxidant gas is supplied from the oxidant gas inlet communication hole 22a to the first oxidant gas flow path 26 of the first separator 14 through the inlet buffer 62a. Another portion of the oxidant gas is introduced into the second oxidant gas flow path 38 of the second separator 18 through the inlet buffer portion 74a.

  The oxidant gas moves along the first oxidant gas flow path 26 in the direction of arrow B (horizontal direction), as shown in FIGS. 1, 3 and 4, and is supplied to the cathode electrode 54 of the first MEA 16a. . Further, the oxidant gas moves in the direction of arrow B along the second oxidant gas flow path 38, and is supplied to the cathode electrode 54 of the second MEA 16b.

  On the other hand, as shown in FIG. 1, the fuel gas is introduced from the fuel gas inlet communication hole 24a to the supply flow channel grooves 36a and 44a. In the supply flow channel 36a, the fuel gas is supplied to the first fuel gas flow channel 34 of the second separator 18 through the inlet buffer 68a. In the supply flow channel groove 44a, the fuel gas is supplied to the second fuel gas flow channel 42 of the third separator 20 through the inlet buffer 80a.

  The fuel gas moves in the direction of arrow B along the first fuel gas flow path 34, and is supplied to the anode electrode 56 of the first MEA 16a. Further, the fuel gas moves in the direction of arrow B along the second fuel gas flow channel 42, and is supplied to the anode electrode 56 of the second MEA 16b.

Therefore, in the MEA, the oxidant gas supplied to each cathode electrode 54 and the fuel gas supplied to each anode electrode 56 are consumed by the electrochemical reaction in the electrode catalyst layer to generate power. More specifically, the hydrogen gas in the fuel gas supplied to the anode electrode 56 and passed through the gas diffusion layer is ionized in the electrode catalyst layer to generate protons (H ⁺ ) and electrons. Electrons are taken out as electrical energy for energizing an external load (not shown) electrically connected to the fuel cell 10, while protons reach the cathode electrode 54 through the electrolyte membrane 52. The protons move from the side of the anode electrode 56 to the side of the cathode electrode 54 with the water contained in the electrolyte membrane 52.

  In the electrode catalyst layer of the cathode electrode 54, the protons, the electrons reaching the cathode electrode 54 after energizing the external load, and the oxygen in the oxidant gas supplied to the cathode electrode 54 and passed through the gas diffusion layer It combines with the gas. This results in the formation of water. Hereinafter, this water is also referred to as generated water.

  During the above electrode reaction, in order to cause the electrolyte membrane 52 to exhibit good proton conductivity, it is necessary to maintain the electrolyte membrane 52 in a wet state. Therefore, a fuel gas containing water vapor may be supplied in advance to the fuel gas inlet communication hole 24a.

  Then, the oxidant gas supplied to and consumed by each cathode electrode 54 of the MEA is discharged to the oxidant gas outlet manifold 22b through the outlet buffer portions 62b and 74b. The fuel gas supplied and consumed to the anode electrode 56 of the MEA is discharged to the fuel gas outlet communication hole 24b through the outlet buffer portions 68b and 80b.

  On the other hand, the cooling medium supplied to the pair of left and right cooling medium inlet communication holes 25a is introduced into the cooling medium channel 32, as shown in FIG. The cooling medium is supplied from the cooling medium inlet communication holes 25a to the cooling medium channel 32, and once it flows inward in the direction of arrow C, moves in the direction of arrow B to cool the MEA. The cooling medium moves outward in the direction of arrow C, and is then discharged to the pair of cooling medium outlet communication holes 25b.

  Therefore, at the time of operation of the fuel cell 10, the melted and solidified portions 98a and 98b are exposed to the steam of the generated water generated by the electrochemical reaction in the electrode catalyst layer, the steam supplied with the fuel gas, and the like. Under the present circumstances, as above-mentioned, melt-solidification site | part 98a, 98b is comprised from the long side L1 and the short side L2, and by setting the long side L1 and area to said range, steam natural exfoliation time is said The range has been adjusted.

  For this reason, when the melted and solidified portions 98a and 98b are exposed to water vapor, natural peeling progresses from the edges on both ends of the short side toward the center, and the entire melted and solidified portions 98a and 98b are efficiently and It can be easily peeled off from the separator. This prevents the generation of excessive stress between the first resin frame member 58, the second resin frame member 60, and the separator as the electrolyte membrane 52 expands and contracts during operation of the fuel cell 10, etc. it can.

  As mentioned above, in the 1st temporary assembly 82 and the 2nd temporary assembly 84, the state where the 1st resin frame member 58 and the 2nd resin frame member 60, and the separator were welded is maintained favorable at the time of the assembly of the power generation unit 12. it can. On the other hand, when the fuel cell 10 is in operation, welding between the first resin frame member 58 and the second resin frame member 60 and the separator can be easily peeled off. By passing through the first temporary assembly 82 and the second temporary assembly 84 formed in this way, it is possible to suppress positional deviation between the MEA and the separator as much as possible, and to provide a fuel cell excellent in durability. You can get ten.

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

  A PES (polyether sulfone) is adopted for the resin frame member, and a stainless steel (SUS) is adopted for the separator to form a temporary assembly for the measurement sample, and the shear strength measurement test of the temporary assembly is carried out went. Specifically, as shown below, a temporary assembly according to the example was produced.

First, laser cleaning was performed on the bonding site in the separator as a roughening treatment. Next, the separator and the resin frame member were laminated, and the contact portion was formed by bringing one surface of the resin frame member into contact with the one surface of the separator subjected to the surface roughening treatment. . Next, the long side L1 is 4.0 mm by heating for 10 seconds at 450 ° C. while applying 1N load to the heating portion of the separator with the above heating device among the contact portions. A melt-solidified portion was formed in which the short side L2 was 1.5 mm (area 6 mm ² ). Thus, a temporary assembly obtained by temporarily fixing the separator and the resin frame member by welding is referred to as Example 1.

A temporary assembly according to Example 2 in the same manner as the temporary assembly according to Example 1, except that the long side L1 of the melt solidified portion is 6.0 mm and the short side L2 is 2.0 mm (area 12.0 mm ² ). I got a solid.

A temporary assembly according to the third embodiment is the same as the temporary assembly according to the first embodiment except that the long side L1 of the melt solidified portion is 6.7 mm and the short side L2 is 2.5 mm (area 16.8 mm ² ). I got a solid.

A temporary assembly according to the fourth embodiment is the same as the temporary assembly according to the first embodiment except that the long side L1 of the melt solidified portion is 6.8 mm and the short side L2 is 4.5 mm (area 30.6 mm ² ). I got a solid.

  Shear strength was measured about the temporary assembly which concerns on said Examples 1-3. The shear strength was measured by holding the resin frame member and the separator of the above temporary assembly with a tensile tester and pulling it in a direction (arrow C direction in FIG. 6) horizontal to the surface of the welded and solidified region.

  The measurement results of the shear strength obtained in this manner are shown in FIG. FIG. 7 is a graph showing the relationship between the area of the melt-solidified portion and the peel strength.

From FIG. 7, by setting the area of the melt-solidified area to 3 mm ² or more, the shear strength of the temporary assembly is set to 15 N or more, and the welded state of MEA and separator can be sufficiently maintained at the time of fuel cell assembly. It can be seen that it is possible to make the size.

  In addition, with respect to the temporary assemblies according to the above-mentioned Examples 1, 3 and 4, the steam natural peeling time was measured. The peeling time was measured by placing the temporary assembly in an atmosphere at a temperature of 85 ° C. and a relative humidity of 100%. The results are shown in FIG. FIG. 8 is a graph showing the relationship between the length L2 of the short side of the dissolution / coagulation site and the natural peeling time.

  It was confirmed from FIG. 8 that in the temporary assemblies of Examples 1, 3 and 4, the welding due to the melt-solidified part peels off within 120 hours. Therefore, by setting the short side L2 and the area of the melt-solidified region in the above range, the molten-solidified region is exposed to water vapor during operation of the fuel cell, and the entire melt-solidified region is efficiently and easily peeled off from the separator. can do. Therefore, in the fuel cell of the present invention, it is possible to avoid the occurrence of excessive stress between the resin frame member and the separator accompanying expansion and contraction of the electrolyte membrane during operation.

DESCRIPTION OF SYMBOLS 10 ... Fuel cell 12 ... Power generation unit 14, 18, 20 ... Separator 16a, 16b ... Electrolyte membrane electrode structure 22a ... Oxidant gas inlet communicating hole 22b ... Oxidant gas outlet communicating hole 24a ... Fuel gas inlet communicating hole 24b ... Fuel gas outlet communication hole 25a: cooling medium inlet communication hole 25b: cooling medium outlet communication hole 26, 38 ... oxidant gas channel 30a: inlet connection groove 30b: outlet connection groove 32: cooling medium channel 34, 42: fuel gas Flow path 36a: Supply flow channel groove portion 36b: Discharge flow channel groove portion 46, 48, 50: Seal member 52: Solid polymer electrolyte membrane 54: Cathode electrode 56: Anode electrode 58, 60: Resin frame member 82, 84: Temporary assembly Solid 90: Heating device 92: Base portion 94: Heating rod 96a, 96b: Heating site 98a, 98b: Melting solidification site

Claims (2)

A fuel cell manufacturing method for obtaining a fuel cell through a temporary assembly in which an electrolyte membrane / electrode assembly having a resin frame member at its outer periphery and a metallic separator are laminated and temporarily fixed,
Laminating the electrolyte membrane-electrode assembly and the separator, bringing one surface of the resin frame member and the separator into contact with each other to form a contact portion;
Forming a melted and solidified portion by heating the abutting portion from the other surface of the separator to melt the resin frame member;
Obtaining the fuel cell by laminating the temporary assembly obtained by temporarily fixing the separator and the resin frame member via the melt-solidified portion;
The melt-solidified portion is substantially rectangular with a long side and a short side equal to or less than the long side, wherein the short side has a length of 1 to 5 mm and an area of 3 mm ² It is the above, The manufacturing method of the fuel cell characterized by the above-mentioned. A fuel cell obtained by passing through a temporary assembly in which an electrolyte membrane / electrode assembly having a resin frame member at its outer periphery and a metallic separator are laminated and temporarily fixed,
The resin frame member is formed by melting and solidifying, and the resin frame member has a melting and solidifying portion for temporarily fixing between the resin frame member and the separator at the time of forming the temporary assembly,
The melt-solidified portion is substantially rectangular with a long side and a short side equal to or less than the long side, wherein the short side has a length of 1 to 5 mm and an area of 3 mm ² A fuel cell characterized by the above.

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