Fuel cell stack

Abstract

The invention provides a technology capable of suppressing breakage of a fuel cell. Each of the anode separator and the cathode separator is provided with: a main body section having a first welded section and a second welded section in which the anode separators and the cathode separators of fuel cells adjacent to each other in the stacking direction of the plurality of fuel cells are welded; a main rib part which is arranged between the first welding part and the second welding part and protrudes from the main body part in a manner that the main rib part is separated from the adjacent fuel cell units in the stacking direction; and at least one of a first additional rib part and a second additional rib part, the first additional rib part protruding from the main body part between the main rib part and the first welded part so as to be spaced apart from the main rib part and separated from the adjacent fuel cell units in the stacking direction, and the second additional rib part protruding from the main body part between the main rib part and the second welded part so as to be spaced apart from the adjacent fuel cell units in the stacking direction. The main ribs protrude from the main body so as to be spaced apart from the main ribs and spaced apart from adjacent fuel cells in the stacking direction.

Description

Technical Field

[0001] This invention relates to a fuel cell stack. Background Technology

[0002] Conventionally, fuel cell stacks are known, which are formed by stacking multiple fuel cell units having a membrane electrode gas diffusion layer junction and an anode separator and a cathode separator that hold the membrane electrode gas diffusion layer junction (Patent Document 1). In this technology, a flow path for coolant to flow is formed between the anode separator and the cathode separator of adjacent fuel cell units by ribs respectively provided on the anode separator and the cathode separator. Moreover, the anode separator and the cathode separator of adjacent fuel cell units are welded at both ends of the ribs.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2007-311069 Summary of the Invention

[0004] In fuel cell stacks, loads are sometimes applied in the stacking direction of multiple fuel cell units. When loads are applied to fuel cell units in the stacking direction, stress concentration occurs from the connection between the rib and the main body of the separator to the weld, which may lead to separator cracking, plastic deformation of the separator, or peeling of the weld, resulting in damage to the fuel cell unit.

[0005] The present invention can be implemented in the following ways.

[0006] (1) According to one aspect of the present invention, a fuel cell stack is provided. In a fuel cell stack having multiple fuel cell units stacked together, each of the multiple fuel cell units includes: a membrane electrode gas diffusion layer assembly; and an anode separator and a cathode separator clamping the membrane electrode gas diffusion layer assembly. The anode separator and the cathode separator each include: a main body having: a first weld portion formed by welding the anode separator and the cathode separator of adjacent fuel cell units in the stacking direction of the multiple fuel cell units; and a second weld portion formed by welding the anode separator and the cathode separator of adjacent fuel cell units spaced apart from the first weld portion; and a main rib portion between the first weld portion and the second weld portion, for... The adjacent fuel cell units protrude from the main body in a manner separate along the stacking direction, thereby forming a flow path for coolant to circulate between the anode and cathode spacers of the adjacent fuel cell units; and at least one of a first additional rib and a second additional rib, the first additional rib protruding from the main body between the main rib and the first weld, spaced apart from the main rib and separated from the adjacent fuel cell units along the stacking direction, and the second additional rib protruding from the main body between the main rib and the second weld, spaced apart from the main rib and separated from the adjacent fuel cell units along the stacking direction. According to this arrangement, the anode and cathode spacers each have additional ribs in the region between the main rib and the weld, a region where stress tends to concentrate when a load is applied to the fuel cell unit in the stacking direction. This allows the stress generated in the spacers by applying a load to the fuel cell unit in the stacking direction to be released from the main rib side to the additional rib side. Therefore, when a load is applied to the fuel cell unit in the stacking direction, stress concentration from the connection between the main rib and the weld to the weld can be avoided. This helps to prevent damage to the fuel cell unit caused by separator breakage, plastic deformation of the separator, or weld peeling.

[0007] (2) In the above method, the height of the additional rib can be less than half the height of the main rib. According to this method, by setting the height of the additional rib to less than half the height of the main rib, stress can be released more reliably from the main rib side to the additional rib side. Therefore, when a load is applied to the fuel cell unit in the stacking direction, stress concentration from the connection between the main rib and the weld to the weld can be more reliably avoided. Thus, fuel cell unit damage can be suppressed more reliably.

[0008] (3) In the above method, the shape of the additional rib can be a plane symmetrical about the plane along the stacking direction and the extension direction of the additional rib. According to this method, by setting the shape of the additional rib to be a plane symmetrical about the plane along the stacking direction of the fuel cell unit and the extension direction of the additional rib, stress can be released more reliably from the main rib side to the additional rib side. As a result, when a load is applied to the fuel cell unit in the stacking direction, stress concentration from the connection between the main rib and the weld to the weld can be more reliably avoided. Therefore, fuel cell unit damage can be suppressed more reliably.

[0009] (4) In the above method, the main rib has a flat portion forming the top of the main rib, and the separation distance between the additional rib and the main rib can be less than or equal to the width of the flat portion.

[0010] According to this method, by setting the separation distance between the additional rib and the main rib to be less than the width of the flat portion, stress can be more reliably released from the main rib side towards the additional rib side. Therefore, when a load is applied to the fuel cell unit in the stacking direction, stress concentration from the connection between the main rib and the weld to the weld can be more reliably avoided. Consequently, fuel cell unit damage can be more reliably suppressed.

[0011] (5) In the above-described manner, the radius of curvature of the connection between the additional rib and the main body can be 0.5 or more. According to this method, by setting the radius of curvature of the connection between the additional rib and the main body to 0.5 or more, stress can be released more reliably from the main rib side towards the additional rib side. Therefore, when a load is applied to the fuel cell unit in the stacking direction, stress concentration from the connection between the main rib and the weld to the weld can be more reliably avoided. Thus, fuel cell unit damage can be more reliably suppressed.

[0012] This invention can be implemented in various ways other than the fuel cell stack described above. For example, it can be implemented as a mobile body such as a vehicle equipped with a fuel cell stack, or as a method for manufacturing a fuel cell stack. Attached Figure Description

[0013] Figure 1 This is a diagram showing the general structure of a fuel cell stack.

[0014] Figure 2 This is a plan view of the fuel cell unit in the first embodiment.

[0015] Figure 3 yes Figure 2 Sectional view III-III.

[0016] Figure 4This is a cross-sectional schematic diagram of a fuel cell unit used as a reference example.

[0017] Figure 5 This is a cross-sectional schematic diagram of the fuel cell unit in the first embodiment.

[0018] Figure 6 This is a schematic perspective view of the fuel cell unit in the first embodiment.

[0019] Figure 7 This is a cross-sectional schematic diagram of the fuel cell unit in the second embodiment.

[0020] Figure 8 This is a cross-sectional schematic diagram of the fuel cell unit in the third embodiment. Detailed Implementation

[0021] A. Implementation Method 1:

[0022] Figure 1 This is a diagram showing a schematic structure of a fuel cell stack 1. The fuel cell stack 1 receives a fuel gas such as hydrogen and an oxidant gas such as air or oxygen, and generates electricity through an electrochemical reaction. The fuel cell stack 1 has a stacked structure in which multiple fuel cell units 100 are stacked. For example, the fuel cell stack 1 is a stack consisting of, in sequence, a first end plate 2a, a first insulating plate 3a, a first current collector plate 4a, multiple fuel cell units 100, a second current collector plate 4b, a second insulating plate 3b, and a second end plate 2b. The fuel cell stack 1 is secured under a load applied along the stacking direction DL of the multiple fuel cell units 100, causing the multiple fuel cell units 100 to be compressed from the end plates 2a and 2b located on both sides.

[0023] Multiple fuel cell units 100 each have a plate component 10. The plate component 10 has a membrane electrode gas diffusion layer assembly 11 (MEGA) and a frame 12.

[0024] The membrane electrode gas diffusion layer assembly 11 has a membrane electrode assembly (MEA) 110. The membrane electrode assembly 110 has an electrolyte membrane 111, an anode catalyst layer 112 disposed on one side of the electrolyte membrane 111, and a cathode catalyst layer 113 disposed on the other side of the electrolyte membrane 111. The electrolyte membrane 111 selectively allows specific ions to permeate.

[0025] In the electrolyte membrane 111, a fluoropolymer-based ion exchange membrane can be used, for example. The anode catalyst layer 112 catalyzes the electrochemical reaction on the anode side. The cathode catalyst layer 113 catalyzes the electrochemical reaction on the cathode side. In each catalyst layer 112 and 113, a carbon support carrying a platinum catalyst can be used, for example. The membrane electrode gas diffusion layer assembly 11 further includes: an anode gas diffusion layer 118 disposed opposite to the anode catalyst layer 112; and a cathode gas diffusion layer 119 disposed opposite to the cathode catalyst layer 113. The anode gas diffusion layer 118 diffuses fuel gas and supplies it to the anode catalyst layer 112. The cathode gas diffusion layer 119 diffuses oxidant gas and supplies it to the cathode catalyst layer 113. In each gas diffusion layer 118 and 119, carbon paper can be used, for example.

[0026] The frame 12 has an opening 13 in its central portion. The frame 12 is a rectangular frame. The outer peripheral portion 11r of the membrane electrode gas diffusion layer assembly 11 is bonded to the opening 13 of the frame 12 by an adhesive. Thus, the frame 12 supports the membrane electrode gas diffusion layer assembly 11. In this embodiment, the frame 12 is a three-layer sheet in which an anode-side adhesive layer 121, a core layer 122, and a cathode-side adhesive layer 123 are sequentially stacked. The anode-side adhesive layer 121 is bonded to the flat portion of the anode separator 20 (described later) by pressure. The cathode-side adhesive layer 123 is bonded to the flat portion of the cathode separator 30 (described later) by pressure. In each adhesive layer 121, 123, elastic components such as rubber components can be used, for example. In each adhesive layer 121, 123, a thermoplastic resin with adhesive properties such as modified polyolefin can be used. In the core layer 122, resins with excellent electrical insulation and air impermeability, such as polyethylene naphthalate (PEN), polyphenylene sulfide (PPS), and polyphenylene ether (PPE), can be used.

[0027] Furthermore, each of the multiple fuel cell units 100 includes an anode separator 20 and a cathode separator 30 for holding the plate component 10. Each separator 20, 30 separates the plate component 10 from the other fuel cell units 100. The anode separator 20 is arranged opposite to the anode gas diffusion layer 118. The cathode separator 30 is arranged opposite to the cathode gas diffusion layer 119. For example, pressed, plate-shaped components such as titanium steel, stainless steel, or carbon components with excellent conductivity, air tightness, and coolant impermeability can be used in each separator 20, 30.

[0028] The frame 12 and each of the partitions 20 and 30 have manifolds 41-46 for fluid flow. The manifolds 41-46 are formed in overlapping positions in the stacking direction DL. Thus, fuel gas is distributed to the anode side of the fuel cell unit 100, oxidant gas is distributed to the cathode side of the fuel cell unit 100, and coolant is distributed between adjacent fuel cell units 100. In this embodiment, fuel gas is supplied to the fourth manifold 44. The fuel gas supplied to the fourth manifold 44 is distributed to the anode side of each fuel cell unit 100. Fuel gas distributed to the anode side that is not used for power generation is discharged from the third manifold 43 to the outside of the fuel cell stack 1. The fuel gas discharged to the outside of the fuel cell stack 1 is then supplied back to the fourth manifold 44. Oxidant gas is supplied to the first manifold 41. The oxidant gas supplied to the first manifold 41 is distributed to the cathode side of each fuel cell unit 100. Oxidant gas distributed to the cathode side that is not used for power generation is discharged from the sixth manifold 46 to the outside of the fuel cell stack 1. The oxidant gas discharged to the outside of the fuel cell stack 1 is then supplied back to the first manifold 41. Coolant for cooling the fuel cell units 100 is supplied to the second manifold 42. The coolant supplied to the second manifold 42 is distributed between adjacent fuel cell units 100. The coolant flowing between adjacent fuel cell units 100 is discharged from the fifth manifold 45 to the outside of the fuel cell stack 1. The coolant discharged to the outside of the fuel cell stack 1 is then supplied back to the second manifold 42.

[0029] Figure 2 This is a plan view of the fuel cell unit 100 in the first embodiment. Figure 2 The image shows a schematic view from the cathode separator 30 side of the stacked multiple fuel cell units 100. Figure 3 yes Figure 2 Sectional view III-III. (See example) Figure 3 As shown, the anode separator 20 and the cathode separator 30 respectively have main body portions 21 and 31 and main rib portions 23 and 33.

[0030] The main body portions 21 and 31 have first welded portions 211 and 311 and second welded portions 212 and 312. The first welded portions 211 and 311 are formed by welding the anode separator 20 and cathode separator 30 of adjacent fuel cell units 100 in the stacking direction DL. The second welded portions 212 and 312 are formed by welding the anode separator 20 and cathode separator 30 of adjacent fuel cell units 100 in the stacking direction DL to the first welded portions 211 and 311 at intervals. In this embodiment, as... Figure 2As shown, the first weld portions 211 and 311 are formed integrally over the outer periphery of the fuel cell unit 100. The second weld portions 212 and 312 are formed parallel to the first weld portions 211 and 311, extending from between the first weld portions 211 and 311 and the manifolds 41-46, and from between the first weld portions 211 and 311 and the outer periphery 11r of the membrane electrode gas diffusion layer junction 11. Each weld portion 211, 212, 311, and 312 is formed, for example, by laser welding.

[0031] like Figure 3 As shown, the main ribs 23 and 33 protrude from the main body portions 21 and 31 between the first weld portions 211 and 311 and the second weld portions 212 and 312, separating from adjacent fuel cell units 100 along the stacking direction DL. The main rib 23 of the anode separator 20 and the main rib 33 of the cathode separator 30 are formed at a position where they overlap each other along the stacking direction DL. Thus, the main ribs 23 and 33 form a flow path 40 for coolant to flow between the anode separator 20 and the cathode separator 30 of adjacent fuel cell units 100. In this embodiment, as Figure 2 As shown, the main ribs 23 and 33 are formed parallel to the first welded portions 211 and 311 and the second welded portions 212 and 312.

[0032] like Figure 3 As shown, the main ribs 23 and 33 have flat portions 231 and 331 and inclined portions 235, 237, 335, and 337. The flat portions 231 and 331 are the flat parts forming the tops 231t and 331t of the main ribs 23 and 33. The tops 231t and 331t of the main ribs 23 and 33 are the parts protruding from the main ribs 23 and 33. The inclined portions 235, 237, 335, and 337 are connected to the flat portions 231 and 331 and the main body portions 21 and 31. The inclined portions 235, 237, 335, and 337 are portions that slope from the flat portions 231 and 331.

[0033] Multiple main ribs 23 and 33 arranged in the stacking direction DL function as springs, originating from the areas where the main ribs 23 and 33 connect to the main body portions 21 and 31 (connecting portions 281, 282, 381, 382) to the weld portions 211, 212, 311, 312. Through the elastic force caused by the elastic deformation of the main ribs 23 and 33 and the stroke corresponding to the elastic force of the adhesive layers 121 and 123 in contact with the main ribs 23 and 33, the anode separator 20 and the cathode separator 30 are sealed within the fuel cell unit 100, and the reactant gas is sealed.

[0034] Figure 4 This is a cross-sectional schematic diagram of a 100V fuel cell unit as a reference example. Figure 4The diagram schematically illustrates a fuel cell unit 100V, which will be used as a reference example, in conjunction with... Figure 3 The cut surface is obtained by cutting in the same way. As a reference example, the 100V fuel cell unit possesses whether or not it has... Figure 3 The additional ribs 25, 27, 35, 37 shown have partitions 20v and 30v that have main body portions 21, 31 and main rib portions 23, 33.

[0035] When a load F is applied to the fuel cell unit 100v in the stacking direction DL, stress tends to concentrate in region P from the inclined portions 235, 237, 335, 337 of the main ribs 23, 333 to the connection portions 281, 282, 381, 382 of the main body portions 21, 31, to the weld portions 211, 212, 311, 312. This can lead to breakage or plastic deformation of the separators 20v, 30v, or peeling of the weld portions 211, 212, 311, 312, potentially resulting in damage to the fuel cell unit 100v. Therefore, it is necessary to deform the main ribs 23, 33 within the elastic region without reaching the plastic region to reduce the stress generated in the separators 20v, 30v. For example, when the separators 20v and 30v are made of metal, in order to allow the main ribs 23 and 33 to deform within the elastic region, the stress generated in the separators 20v and 30v needs to be adjusted to be less than 0.2% of the endurance of the metal material constituting the separators 20v and 30v. In this case, by adjusting the plate thicknesses t1 and t2 of the separators 20v and 30v or increasing the width W1 of the flat portions 231 and 331, the stress generated in the separators 20v and 30v can be reduced. However, by increasing the width W1 of the flat portions 231 and 331, the dimensions of the separators 20v and 30v may sometimes increase. When the dimensions of the separators 20v and 30v increase, it may lead to design changes requiring the addition of dimensions to other components such as the frame 12, or increased manufacturing costs due to additional material costs based on the increase in the dimensions of each component.

[0036] Therefore, in order to reduce the stress generated in the separators 20 and 30 within the same area without changing the size of the fuel cell stack 1, the separators 20 and 30 in this embodiment adopt the following structure. For example... Figure 3As shown, each separator 20, 30 also includes a first additional rib 25, 35 and a second additional rib 27, 37. The first additional ribs 25, 35 protrude from the main body portions 21, 31 between the main ribs 23, 33 and the first weld portions 211, 311, spaced apart from the main ribs 23, 33 and separated from the adjacent fuel cell units 100 along the stacking direction DL. The second additional ribs 27, 37 protrude from the main body portions 21, 31 between the main ribs 23, 33 and the second weld portions 212, 312, spaced apart from the main ribs 23, 33 and separated from the adjacent fuel cell units 100 along the stacking direction DL. In addition, the main ribs 23, 33, the first additional ribs 25, 35, and the second additional ribs 27, 37 are ribs formed by bending a portion of the separators 20, 30.

[0037] Figure 5 This is a cross-sectional schematic diagram of the fuel cell unit 100 in the first embodiment. Figure 5 The diagram schematically illustrates the connection between the fuel cell unit 100 in this embodiment and... Figure 3 The cutting surface when cut in the same way. Figure 6 This is a schematic perspective view of the fuel cell unit 100 in the first embodiment.

[0038] exist Figure 6 The image shows a perspective view of a cross-section along the stacking direction DL of the stacked multiple fuel cell units 100.

[0039] like Figure 5 As shown, the first additional rib 25 of the anode spacer 20 and the first additional rib 35 of the cathode spacer 30 are formed at a position where they overlap each other along the lamination direction DL. The second additional rib 27 of the anode spacer 20 and the second additional rib 37 of the cathode spacer 30 are formed at a position where they overlap each other along the lamination direction DL. In this embodiment, as... Figure 6 As shown, additional ribs 25, 27, 35, and 37 are formed parallel to the main ribs 23 and 33.

[0040] like Figure 5As shown, the additional ribs 25, 27, 35, and 37 have top portions 251, 271, 351, and 371, and slope portions 255, 257, 275, 277, 355, 357, 375, and 377. The top portions 251, 271, 351, and 371 are the portions including the tops 251t, 271t, 351t, and 371t of the additional ribs 25, 27, 35, and 37. The tops 251t, 271t, 351t, and 371t of the additional ribs 25, 27, 35, and 37 are the protruding portions of the additional ribs 25, 27, 35, and 37. The slope portions 255, 257, 275, 277, 355, 357, 375, and 377 are connected to the top portions 251, 271, 351, and 371. The sloping sections 255, 257, 275, 277, 355, 357, 375, and 377 are the portions that slope from the top sections 251, 271, 351, and 371.

[0041] In this embodiment, the shape of the anode separator 20 is the same as the shape of the cathode separator 30. That is, the shape of the first additional rib 25 in the anode separator 20 is the same as the shape of the first additional rib 35 in the cathode separator 30. The shape of the second additional rib 27 in the anode separator 20 is the same as the shape of the second additional rib 37 in the cathode separator 30. Furthermore, the shape of the first additional rib 25 in the anode separator 20 is the same as the shape of the second additional rib 27 in the anode separator 20. The shape of the first additional rib 35 in the cathode separator 30 is the same as the shape of the second additional rib 37 in the cathode separator 30. And, as... Figure 5 and Figure 6 As shown, when the additional ribs 25, 27, 35, and 37 are observed individually, their shapes are symmetrical about the plane with the plane along the stacking direction DL and the extension direction DE of the additional ribs 25, 27, 35, and 37 as the plane of symmetry S.

[0042] like Figure 5 As shown, the height H1 of the additional ribs 25, 27, 35, and 37 is less than half the height H2 of the main ribs 23 and 33. The height H1 of the additional ribs 25, 27, 35, and 37 corresponds to the height difference in the lamination direction DL of the connecting portions 283-286, 383-386 between the additional ribs 25, 27, 35, and 37 and the main body portions 21 and 31, and the tops 251t, 271t, 351t, and 371t of the additional ribs 25, 27, 35, and 37. The height H2 of the main ribs 23 and 33 corresponds to the height difference in the lamination direction DL of the connecting portions 281, 282, 381, and 382 between the main ribs 23 and 33 and the main body portions 21 and 31, and the tops 231t and 331t of the main ribs 23 and 33.

[0043] The separation distance W2 between the additional ribs 25, 27, 35, 37 and the main ribs 23, 33 is less than or equal to the width W1 of the flat portions 231, 331. The width W1 of the flat portions 231, 331 corresponds to the dimensions of the flat portions 231, 331 in the width direction DW of the fuel cell unit 100. The width direction DW of the fuel cell unit 100 is a direction orthogonal to the stacking direction DL and the extension direction DE. The separation distance W2 between the additional ribs 25, 27, 35, 37 and the main ribs 23, 33 corresponds to the separation distance in the width direction DW between the connecting portions 283-286, 383-386 of the additional ribs 25, 27, 35, 37 and the main body portions 21, 31, and the connecting portions 281, 282, 381, 382 of the main ribs 23, 33 and the main body portions 21, 31.

[0044] The radius of curvature R of the connecting portions 283-286 and 383-386 between the additional ribs 25, 27, 35, 37 and the main body portions 21, 31 is 0.5 or more. That is, the connecting portions 283-286 and 383-386 between the additional ribs 25, 27, 35, 37 and the main body portions 21, 31 have a predetermined rounded corner.

[0045] According to the above embodiment, the separators 20 and 30 have additional ribs 25, 27, 35, and 37 located between the main ribs 23 and 33 and the welded portions 211, 212, 311, and 312, i.e., at positions where stress tends to concentrate when a load F is applied to the fuel cell unit 100 in the stacking direction DL. In this way, by applying a load F to the fuel cell unit 100 in the stacking direction DL, the stress generated in the separators 20 and 30 can be released from the main ribs 23 and 33 to the additional ribs 25, 27, 35, and 37. Therefore, when a load F is applied to the fuel cell unit 100 in the stacking direction DL, stress concentration can be avoided from the connection portions 281, 282, 381, and 382 between the main ribs 23 and 33 and the welded portions 211, 212, 311, and 312 to the welded portions 211, 212, 311, and 312. Therefore, it can suppress the damage to the fuel cell unit 100 caused by the cracking of the separators 20 and 30, plastic deformation of the separators 20 and 30, or peeling of the welds 211, 212, 311, 312.

[0046] Furthermore, according to the above embodiment, the stress generated in the separators 20 and 30 can be reduced within the same area without changing the size of the fuel cell stack 1. This avoids the drawbacks of design changes or increased manufacturing costs resulting from increasing the size of the separators 20 and 30.

[0047] Furthermore, according to the above embodiment, the separators 20 and 30 are provided with additional ribs 25, 27, 35, and 37 at both ends of the main ribs 23 and 33, respectively. In this way, by applying a load F to the fuel cell unit 100 in the stacking direction DL, the stress generated in the separators 20 and 30 can be more reliably released from the main ribs 23 and 33 towards the additional ribs 25, 27, 35, and 37. Therefore, when a load F is applied to the fuel cell unit 100 in the stacking direction DL, stress concentration from the connection portions 281, 282, 381, 382 between the main ribs 23 and 33 and the weld portions 211, 212, 311, 312 to the weld portions 211, 212, 311, 312 can be more reliably prevented. Thus, damage to the fuel cell unit 100 can be more reliably suppressed. Alternatively, the partitions 20 and 30 may not have the first additional ribs 25 and 35, but may have the second additional ribs 27 and 37. The partitions 20 and 30 may not have the second additional ribs 27 and 37, but may have the first additional ribs 25 and 35.

[0048] Furthermore, according to the above embodiment, the height H1 of the additional ribs 25, 27, 35, and 37 is less than half the height H2 of the main ribs 23 and 33. In this way, by applying a load F to the fuel cell unit 100 in the stacking direction DL, the stress generated in the separators 20 and 30 can be more reliably released from the main ribs 23 and 33 towards the additional ribs 25, 27, 35, and 37. Therefore, when a load F is applied to the fuel cell unit 100 in the stacking direction DL, stress concentration from the connections 281, 282, 381, and 382 between the main ribs 23 and 33 and the welds 211, 212, 311, and 312 to the welds 211, 212, 311, and 312 can be more reliably prevented. Thus, damage to the fuel cell unit 100 can be more reliably suppressed. In addition, the height H1 of the additional ribs 25, 27, 35, and 37 is not limited to the above, and can also be greater than half the height H2 of the main ribs 23 and 33.

[0049] Furthermore, according to the above embodiment, the additional ribs 25, 27, 35, and 37 are symmetrical about a plane with a symmetry plane S along the stacking direction DL and the extension direction DE. In this way, by applying a load F to the fuel cell unit 100 in the stacking direction DL, the stress generated in the separators 20 and 30 can be more reliably released from the main ribs 23 and 33 towards the additional ribs 25, 27, 35, and 37. Therefore, when a load F is applied to the fuel cell unit 100 in the stacking direction DL, stress concentration from the connection portions 281, 282, 381, and 382 between the main ribs 23 and 33 and the weld portions 211, 212, 311, and 312 to the weld portions 211, 212, 311, and 312 can be more reliably prevented. Therefore, damage to the fuel cell unit 100 can be more reliably suppressed. Furthermore, the shapes of the additional ribs 25, 27, 35, and 37 are not limited to those described above, and may also be shapes other than those symmetrical about the plane with the plane along the stacking direction DL and the extension direction DE as the plane of symmetry S.

[0050] Furthermore, according to the above embodiment, the separation distance W2 between the additional ribs 25, 27, 35, 37 and the main ribs 23, 33 is less than or equal to the width W1 of the flat portions 231, 331 of the main ribs 23, 33. In this way, the smaller the separation distance W2 between the additional ribs 25, 27, 35, 37 and the main ribs 23, 33, the more reliably the stress generated when a load F is applied to the fuel cell unit 100 in the stacking direction DL can be released from the main ribs 23, 33 side toward the additional ribs 25, 27, 35, 37 side. Therefore, when a load F is applied to the fuel cell unit 100 in the stacking direction DL, stress concentration from the connection portions 281, 282, 381, 382 between the main ribs 23, 33 and the weld portions 211, 212, 311, 312 to the weld portions 211, 212, 311, 312 can be more reliably avoided. Therefore, damage to the fuel cell unit 100 can be suppressed more reliably. In addition, the separation distance W2 between the additional ribs 25, 27, 35, 37 and the main ribs 23, 33 is not limited to the above, and may be greater than the width W1 of the flat portion 231, 331 of the main ribs 23, 33.

[0051] Furthermore, according to the above embodiment, the radius of curvature R of the connecting portions 283-286, 383-386 between the additional ribs 25, 27, 35, 37 and the main body portions 21, 31 is 0.5 or more. In this way, by applying a load F to the fuel cell unit 100 in the stacking direction DL, the stress generated in the separators 20, 30 can be more reliably released from the main ribs 23, 33 side toward the additional ribs 25, 27, 35, 37 side. Therefore, when a load F is applied to the fuel cell unit 100 in the stacking direction DL, stress concentration from the connecting portions 281, 282, 381, 382 between the main ribs 23, 33 and the weld portions 211, 212, 311, 312 to the weld portions 211, 212, 311, 312 can be more reliably prevented. Therefore, damage to the fuel cell unit 100 can be more reliably suppressed. Furthermore, the radius of curvature R of the connecting portions 283-286 and 383-386 between the additional ribs 25, 27, 35, 37 and the main body portions 21, 31 is not limited to the above, and may be less than 0.5.

[0052] B. Second Implementation Method:

[0053] Figure 7 This is a cross-sectional schematic diagram of the fuel cell unit 100a in the second embodiment. Figure 7 The diagram schematically illustrates the connection between the fuel cell unit 100a in this embodiment and... Figure 3 The cutting surface is cut in the same manner. In this embodiment, the shapes of the first additional ribs 25a and 35a of each separator 20a and 30a are different from those in the first embodiment. Other structures are the same as in the first embodiment.

[0054] That is, in this embodiment, the shapes of the first additional ribs 25a and 35a and the second additional ribs 27 and 37 are different in the same separators 20a and 30a. Even in this way, the stress in the separators 20a and 30a generated by applying a load F to the fuel cell unit 100a in the stacking direction DL can be released more reliably from the main ribs 23 and 33 side toward the additional ribs 25a, 27, 35a, and 37 side. As a result, when a load F is applied to the fuel cell unit 100a in the stacking direction DL, stress concentration from the connection portions 281, 282, 381, 382 between the main ribs 23 and 33 and the weld portions 211, 212, 311, 312 to the weld portions 211, 212, 311, 312 can be more reliably avoided.

[0055] C. Third implementation method:

[0056] Figure 8 This is a cross-sectional schematic diagram of the fuel cell unit 100b in the third embodiment. Figure 8The diagram schematically illustrates the connection between the fuel cell unit 100b in this embodiment and... Figure 3 The cutting surface is cut in the same way. In this embodiment, the shape of the anode separator 20b is different from that in the first embodiment. Other structures are the same as in the first embodiment. That is, in this embodiment, the shapes of the first additional ribs 25b and 35 and the shapes of the second additional ribs 27b and 37 in the anode separator 20b and the cathode separator 30 are different, respectively. Even in this way, it is possible to more reliably release the stress in the separators 20b and 30 generated by applying a load F to the fuel cell unit 100b in the stacking direction DL from the main ribs 23 and 33 side toward the additional ribs 25b, 27b, 35 and 37 side. Therefore, when a load F is applied to the fuel cell unit 100b in the stacking direction DL, stress concentration can be more reliably avoided from the connection portions 281, 282, 381, 382 between the main ribs 23, 33 and the weld portions 211, 212, 311, 312 to the weld portions 211, 212, 311, 312.

[0057] This invention is not limited to the embodiments described above, and can be implemented in various configurations without departing from its spirit. For example, in order to address some or all of the above-described issues, or to achieve some or all of the above-described effects, the technical features of the embodiments corresponding to the technical features in the various forms described in the summary section of the invention can be appropriately replaced or combined. Furthermore, if a technical feature is not required to be described in this specification, it can be appropriately deleted.

[0058] Symbol Explanation

[0059] 1-Fuel cell stack, 2a-First end plate, 2b-Second end plate, 3a-First insulating plate, 3b-Second insulating plate, 4a-First current collector plate, 4b-Second current collector plate, 10-Plate component, 11-Membrane electrode gas diffusion layer junction, 11r-Outer periphery of membrane electrode gas diffusion layer junction, 12-Frame, 13-Opening, 20, 20a, 20b, 20v-Anode separator, 21-Main body of anode separator, 23-Main rib of anode separator, 25, 25a, 25b-First additional rib of anode separator, 27, 27b-Second additional rib of anode separator, 30, 30a, 30v-Cathode separator, 31-Main body of cathode separator, 33-Main rib of cathode separator Part, 35, 35a - First additional rib of cathode separator, 37 - Second additional rib of cathode separator, 40 - Flow path, 41 - First manifold, 42 - Second manifold, 43 - Third manifold, 44 - Fourth manifold, 45 - Fifth manifold, 46 - Sixth manifold, 100, 100a, 100b, 100v - Fuel cell unit, 110 - Membrane electrode assembly, 111 - Electrolyte membrane, 112 - Anode catalyst layer, 113 - Cathode catalyst layer, 118 - Anode gas diffusion layer, 119 - Cathode gas diffusion layer, 121 - Anode side bonding layer, 122 - Core layer, 123 - Cathode side bonding layer, 211 - First weld of anode separator, 212 - Second weld of anode separator, 231 - Flat portion of the main rib in the anode separator, 231t - Top of the main rib in the anode separator, 235, 237 - Inclined portion of the main rib in the anode separator, 251 - Top surface of the first additional rib in the anode separator, 251t - Top of the first additional rib in the anode separator, 255, 257 - Inclined portion of the first additional rib in the anode separator, 271 - Top surface of the second additional rib in the anode separator, 271t - Top of the second additional rib in the anode separator, 275, 277 - Inclined portion of the second additional rib in the anode separator, 281, 282 - Connection between the main rib and the main body in the anode separator, 283, 284 - Connection between the first additional rib and the main body in the anode separator. The connecting portion of the body, 285, 286 - the connecting portion between the second additional rib in the anode separator and the main body, 311 - the first welded portion of the cathode separator, 312 - the second welded portion of the cathode separator, 331 - the flat portion of the main rib in the cathode separator, 331t - the top of the main rib in the cathode separator, 335, 337 - the inclined portion of the main rib in the cathode separator, 351 - the top surface of the first additional rib in the cathode separator, 351t - the top of the first additional rib in the cathode separator, 355, 357 - the inclined surface of the first additional rib in the cathode separator, 371 - the top surface of the second additional rib in the cathode separator, 371t - the top of the second additional rib in the cathode separator, 375...377 - The inclined portion of the second additional rib in the cathode separator; 381, 382 - The connection between the main rib and the main body in the cathode separator; 383, 384 - The connection between the first additional rib and the main body in the cathode separator; 385, 386 - The connection between the second additional rib and the main body in the cathode separator; DE - Extension direction; DL - Stacking direction; DW - Width direction; F - Load; H1 - Height of the additional rib; H2 - Height of the main rib; P - Region; R - Radius of curvature; S - Symmetry plane; t1 - Thickness of the anode separator; t2 - Thickness of the cathode separator; W1 - Width of the flat portion; W2 - Separation distance between the additional rib and the main rib.

Claims

1. A fuel cell stack, comprising multiple stacked fuel cell units, characterized in that, Each of the plurality of fuel cell units comprises: Membrane electrode gas diffusion layer bonding assembly; and Anode separators and cathode separators, which clamp the membrane electrode gas diffusion layer assembly, The anode separator and the cathode separator each comprise: The main body includes: a first welding portion formed by welding the anode separator and the cathode separator of adjacent fuel cell units in the stacking direction of the plurality of fuel cell units; and a second welding portion formed by welding the anode separator and the cathode separator of adjacent fuel cell units apart from the first welding portion. A main rib, which protrudes from the main body between the first weld and the second weld in a manner that separates from the adjacent fuel cell unit along the stacking direction, thereby forming a flow path for coolant to flow between the anode separator and the cathode separator of the adjacent fuel cell unit; and At least one of the first additional rib and the second additional rib, the first additional rib protruding from the main body between the main rib and the first welded portion, spaced apart from the main rib and separated from the adjacent fuel cell unit along the stacking direction, and the second additional rib protruding from the main body between the main rib and the second welded portion, spaced apart from the main rib and separated from the adjacent fuel cell unit along the stacking direction.

2. The fuel cell stack according to claim 1, characterized in that, The height of the additional rib is less than half the height of the main rib.

3. The fuel cell stack according to claim 1, characterized in that, The shape of the additional rib is a plane-symmetrical shape with the plane along the stacking direction and the extension direction of the additional rib as the plane of symmetry.

4. The fuel cell stack according to claim 1, characterized in that, The main rib has a flat portion forming the top of the main rib. The distance between the additional rib and the main rib is less than or equal to the width of the flat portion.

5. The fuel cell stack according to claim 1, characterized in that, The radius of curvature of the connection between the additional rib and the main body is 0.5 or more.

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