Fuel cell stack

Abstract

This fuel cell stack is provided with a plurality of stacked cells, and a first cell is provided with a membrane electrode assembly, a frame, a pair of separators that sandwich and hold the membrane electrode assembly of the frame, and an elastic body that has a base and a plurality of pillar sections that protrude from the base. A first separator provided in a first battery cell includes a groove portion on a first surface. The base part of the elastic body is arranged in the groove part. The base portion covers the bottom surface of the groove portion, and at least a portion of the plurality of pillar portions is disposed in the direction in which the groove portion extends. In a cooling liquid flow path space formed between a first battery cell and a second battery cell adjacent to the first battery cell, the front ends of a plurality of column parts of an elastic body arranged in a groove part of a first separator are in contact with a second separator provided in the second battery cell.

Description

Technical Field

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

[0002] In the technology described in Japanese Patent Application Publication No. 2021-97001, a displacement suppression member is disposed in the flow path space of the coolant. The flow path space of the coolant is formed by a separator provided by one of the multiple battery cells constituting a fuel cell stack and separators provided by other battery cells overlapping with that battery cell. The displacement suppression member is fixed to the separator provided by one of the battery cells to suppress displacement of the separator caused by pressure changes of the coolant flowing in the flow path space. The displacement suppression member has multiple protrusions and connecting pieces connecting the multiple protrusions. The front ends of the multiple protrusions abut against the separator opposite to which the displacement suppression member is fixed. Summary of the Invention

[0003] In the technology described in Japanese Patent Application Publication No. 2021-97001, the pressure of the coolant flowing in the flow path space is applied to the displacement suppression member. When the coolant pressure increases, it is possible for the displacement suppression member to shift position or for the displacement suppression member to detach from the partition.

[0004] The present invention can be implemented in the following ways.

[0005] (1) According to one aspect of the present invention, a fuel cell stack is provided. In this fuel cell stack,

[0006] The first battery cell among the plurality of battery cells includes:

[0007] Membrane electrode assembly;

[0008] A frame that holds the membrane electrode assembly;

[0009] A pair of partitions that clamp and hold the membrane electrode assembly within the frame; and

[0010] One or more elastomers having a base and a plurality of columnar portions protruding from the base.

[0011] The first battery cell has one or more grooves on one of the pair of separators on the first surface, which is opposite to the surface opposite to the other of the pair of separators.

[0012] The base of the one or more elastomers is disposed in the one or more grooves.

[0013] The base covers the bottom surface of one or more of the grooves.

[0014] At least a portion of the plurality of columns are arranged along the direction in which the one or more grooves extend.

[0015] In the flow space of the coolant formed between the first battery cell and the second battery cell adjacent to the first battery cell, that is, in the gap formed by overlapping the second partition of the second battery cell on the first surface of the first partition of the first battery cell, the front ends of the plurality of pillars of the one or more elastic bodies disposed in the one or more grooves of the first partition contact the second partition of the second battery cell.

[0016] According to the above method, the base portion, which is part of the elastomer, is disposed in the groove portion such that it covers the bottom surface of the groove portion formed in the first partition. Therefore, compared to a method where part of the elastomer is not disposed in the groove portion, the area in direct contact between the coolant and the elastomer can be reduced. Therefore, the force exerted on the base portion of the elastomer by the coolant can be reduced. Therefore, compared to a method where part of the elastomer is not disposed in the groove portion, the occurrence of positional displacement and peeling of the elastomer can be suppressed.

[0017] (2) In the fuel cell stack described above,

[0018] The one or more elastomers include a first elastomer and a second elastomer.

[0019] The first elastomer and the second elastomer each have a wall portion protruding from the base, in addition to the base and the plurality of column portions.

[0020] A supply manifold for supplying the coolant to the flow path space and a discharge manifold for discharging the coolant from the flow path space are formed on the first partition.

[0021] The first groove of the more than one groove is formed on the first surface of the first partition to surround the supply manifold.

[0022] The second groove of the more than one groove is formed on the first surface of the first partition to surround the discharge manifold.

[0023] The base of the first elastomer is disposed in the first groove, and the plurality of column portions of the first elastomer are disposed downstream of the wall portion of the first elastomer in the direction from the supply manifold toward the discharge manifold.

[0024] The base of the second elastic body is disposed in the second groove, and the plurality of pillars of the second elastic body can be disposed in the oriented direction at a position further upstream than the wall of the second elastic body.

[0025] According to the above method, in the first elastic body configured to surround the supply manifold that supplies coolant to the flow path space, multiple pillars are arranged downstream of the wall portion in the direction from the supply manifold to the discharge manifold. In the second elastic body configured to surround the discharge manifold that discharges coolant from the flow path space, multiple pillars are arranged upstream of the wall portion. Therefore, the flow of coolant can be made smoother.

[0026] (3) In the fuel cell stack described above,

[0027] With the membrane electrode assembly held in the frame by the first separator and the other of the pair of separators of the first battery cell,

[0028] At the position on the back side corresponding to the location where the one or more slots are provided, the second side of the first partition, opposite to the first side, can contact the frame.

[0029] With the fuel cell stack completed, the elastomer disposed in the flow path space applies a load to the frame via the first separator, while multiple battery cells are stacked. This fixes the frame, which is held between a pair of separators, and the position of the membrane electrode assembly mounted on the frame. According to this method, compared to a method where a portion of the elastomer is not disposed in the groove, it is possible to suppress the occurrence of elastomer displacement and delamination. Attached Figure Description

[0030] Hereinafter, with reference to the accompanying drawings, the features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described, in which the same reference numerals denote the same elements, and wherein:

[0031] Figure 1 This is an explanatory diagram showing the fuel cell unit involved in this embodiment in an exploded view.

[0032] Figure 2 It is along Figure 1 A sectional view cut along line II-II.

[0033] Figure 3 This is a cross-sectional view showing two fuel cell units overlapping.

[0034] Figure 4 This is an explanatory diagram showing an example of the external shape of the elastic part.

[0035] Figure 5 It is along Figure 1 A sectional view cut by the VV line. Detailed Implementation

[0036] A. Implementation method:

[0037] Figure 1 This is an explanatory diagram showing the fuel cell unit 100 according to this embodiment in exploded view. Figure 2 It is along Figure 1 The image shows a cross-sectional view taken along line II-II. The fuel cell unit 100 is a solid polymer fuel cell that generates electricity by receiving hydrogen and oxygen as reactant gases. Multiple fuel cell units 100 are stacked to form a fuel cell stack.

[0038] like Figure 1 As shown, the fuel cell unit 100 includes a membrane electrode assembly (MEA) 10, a resin sheet 20, a pair of separators 30 and 40, a sealing portion 60, and an elastic portion 70. The fuel cell unit 100 is also referred to simply as a "battery unit." The elastic portion 70 is also referred to as an "elastomer." The resin sheet 20 is also referred to as a "frame."

[0039] like Figure 2 As shown, the membrane electrode assembly 10 includes an electrolyte membrane 11, a first electrode catalyst layer 12, a second electrode catalyst layer 13, a first gas diffusion layer 14, and a second gas diffusion layer 15. The first electrode catalyst layer 12 functions as a cathode electrode formed on one side of the electrolyte membrane 11. The second electrode catalyst layer 13 functions as an anode electrode formed on the other side of the electrolyte membrane 11. The first gas diffusion layer 14 is formed on the side of the first electrode catalyst layer 12 that is not in contact with the electrolyte membrane 11. The second gas diffusion layer 15 is formed on the side of the second electrode catalyst layer 13 that is not in contact with the electrolyte membrane 11. The electrolyte membrane 11 is, for example, an ion exchange membrane made of a fluorinated resin. The first electrode catalyst layer 12 and the second electrode catalyst layer 13 are, for example, made of a carbon support carrying a platinum catalyst. The first gas diffusion layer 14 and the second gas diffusion layer 15 are, for example, made of carbon cloth.

[0040] like Figure 1 As shown, the resin sheet 20 serves as a frame-shaped component for holding the membrane electrode assembly 10. For example, it is bonded by an adhesive film F1 (see reference) which is a sheet-like hot-melt adhesive. Figure 2 The outer periphery of the membrane electrode assembly 10 is joined to the inner periphery of the through hole 20h in the center of the resin sheet 20. The membrane electrode assembly 10 is exposed on the surface and back of the resin sheet 20.

[0041] like Figure 2As shown, the resin sheet 20 includes a core layer 21 and adhesive layers 22A and 22B disposed on both sides of the core layer 21. Preferably, the materials constituting the core layer 21 and the adhesive layers 22A and 22B are selected such that the melting point of the core layer 21 is higher than the melting point of the adhesive layers 22A and 22B. The core layer 21 is, for example, made of polyethylene naphthalate (PEN). The adhesive layers 22A and 22B are, for example, made of a modified olefin-based hot-melt adhesive.

[0042] like Figure 1 As shown, separators 30 and 40 clamp and hold the membrane electrode assembly 10 within the resin sheet 20. Separators 30 and 40 are bonded to the resin sheet 20 via adhesive layers 22A and 22B. Separators 30 and 40 are made, for example, of stainless steel, titanium, or alloys thereof. The separators 30 and 40 have protrusions and recesses formed by stamping. Figure 2 As shown, between the separator 30 and the membrane electrode assembly 10, the irregularities provided on the separator 30 form a flow path CF for the flow of oxidizing gas (cathode gas). Between the separator 40 and the membrane electrode assembly 10, the irregularities provided on the separator 40 form a flow path AF for the flow of fuel gas (anode gas).

[0043] like Figure 1 As shown, multiple through holes are formed in the resin sheet 20, partitions 30, and 40. These through holes form multiple manifolds when the resin sheet 20 is held between the partitions 30 and 40. The multiple manifolds include a supply manifold Mio, a supply manifold Mih, a supply manifold Miw, an exhaust manifold Moo, an exhaust manifold Moh, and an exhaust manifold Mow. The supply manifold Mio supplies oxidizing gas to the membrane electrode assembly 10. The supply manifold Mih supplies fuel gas to the membrane electrode assembly 10. The supply manifold Miw supplies coolant. The exhaust manifold Moo discharges the oxidizing gas used in the reaction within the membrane electrode assembly 10. The exhaust manifold Moh discharges the fuel gas used in the reaction within the membrane electrode assembly 10. The exhaust manifold Mow discharges the coolant that receives heat generated within the membrane electrode assembly 10. Additionally, in... Figure 1 In the diagram, the six through holes formed in the partition 30 are marked with symbols 301 to 306.

[0044] like Figure 2 As shown, two grooves 31, formed by stamping, are provided on the surface S1 of the partition 30. One groove 31 is formed to surround the through hole 303 of the partition 30. The other groove 31 is formed to surround the through hole 306. Furthermore, in Figure 2The groove 31 surrounding the through hole 306 of the separator 30 is not shown. When the membrane electrode assembly 10 held in place of the resin sheet 20 is clamped by the separators 30 and 40, the surface S2 of the separator 30 contacts the resin sheet 20 at the back side corresponding to the location where the groove 31 is formed. The groove 31 surrounding the through hole 306 of the separator 30 is also the same. The purpose of the groove 31 will be described later. Surface S1 is also referred to as "first surface". Surface S2 is also referred to as "second surface".

[0045] Figure 3 This is a partial cross-sectional view showing two fuel cell units 100 overlapping. The fuel cell unit 100 positioned on the lower side is designated as fuel cell unit 100A, and the fuel cell unit 100 positioned on the upper side is designated as fuel cell unit 100B. Fuel cell unit 100B is adjacent to fuel cell unit 100A on the side opposite to the partition 40 of fuel cell unit 100A, relative to the partition 30 of fuel cell unit 100A. The gap between the partition 40 of fuel cell unit 100B and the partition 30 of fuel cell unit 100A overlaps and forms a flow path space WF for the flow of coolant to control the temperature of the membrane electrode assembly 10. Fuel cell unit 100A is also referred to as "first fuel cell unit". Fuel cell unit 100B is also referred to as "second fuel cell unit". The partition 30 of fuel cell unit 100A is also referred to as "first partition". The partition 40 of fuel cell unit 100B is also referred to as "second partition".

[0046] like Figure 1 As shown, the sealing part 60 seals the flow path CF of the oxidizing gas and the flow path AF of the fuel gas to prevent the oxidizing gas and fuel gas from entering the flow path space WF. The sealing part 60 is, for example, made of a rubber gasket formed of EPDM (ethylene propylene diene rubber) or a cured in-place gasket (CIPG). The sealing part 60 is joined to the side of the partition 30 that does not face the membrane electrode assembly 10 and the resin sheet 20, i.e., surface S1. The sealing part 60 is arranged to independently surround the through holes 301, 302, 304 and 305. Moreover, the sealing part 60 is arranged along the outer periphery of the partition 30.

[0047] like Figure 1 As shown, the elastic portion 70 includes an elastic portion 71 and an elastic portion 72. (As...) Figure 2 As shown, the elastic portions 71 and 72 are bonded to the side of the partition 30 that does not face the membrane electrode assembly 10 and the resin sheet 20, i.e., surface S1. Figure 1As shown, the elastic portion 71 is disposed in the groove 31 formed around the through hole 303. Therefore, the elastic portion 71 is disposed in such a way that it surrounds the through hole 303 constituting the supply manifold Miw. Although not shown, the elastic portion 72 is disposed in the groove 31 formed around the through hole 306. Therefore, the elastic portion 72 is disposed in such a way that it surrounds the through hole 306 constituting the discharge manifold Mow (see reference). Figure 1 The elastic portions 71 and 72 are formed, for example, by injection molding of the partition 30, which includes the groove portion 31, and by stamping.

[0048] To suppress displacement of the separator 30 of fuel cell unit 100A and the separator 40 of fuel cell unit 100B, elastic portions 71 and 72 are disposed in the flow path space WF. This is because displacement of the separator 30 of fuel cell unit 100A and the separator 40 of fuel cell unit 100B may occur due to pressure fluctuations, temperature fluctuations, and warping during battery cell manufacturing in the flow path space WF. Displacement of the separators 30 and 40 will cause deviations in the flow rate of the coolant in the flow path space WF, which in turn will lead to a decrease in cooling efficiency / power generation efficiency. The groove 31 surrounding the through hole 303 is also referred to as the "first groove". The groove 31 surrounding the through hole 306 is also referred to as the "second groove". The elastic portion 71 is also referred to as the "first elastic body". The elastic portion 72 is also referred to as the "second elastic body".

[0049] With the fuel cell stack completed, the fuel cell units 100 are stacked together. In this state, the elastic portions 71 and 72 disposed in the flow path space WF apply a load to the resin sheet 20 via the separator 30. When the cathode gas pressure and anode gas pressure are higher than the coolant pressure, the sealing performance of the joint between the resin sheet 20 and the separators 30 and 40 decreases. By applying a load to the resin sheet 20 through the elastic portions 71 and 72, the resin sheet 20, which is held between the separators 30 and 40, can be securely sealed.

[0050] Figure 4 This is an explanatory diagram showing an example of the external shape of the elastic part 71. Figure 4 The text is a jumbled mess of characters and symbols, making it impossible to translate accurately. It appears to be a corrupted or incomplete sentence or a fragment of a longer text. Figure 1 A perspective view of the elastic part 71 enclosed by the rectangular frame IV shown by the dashed line. Figure 5 It is along Figure 1A cross-sectional view taken along the VV line. Hereinafter, the elastic part 71 will be described as an example, but the elastic part 72 also has the same structure. The elastic part 71 includes a base 71A, a plurality of pillars 71B, and a wall 71C. The plurality of pillars 71B and the wall 71C protrude from the base 71A. The base 71A is arranged to cover the bottom surface of the groove 31. The base 71A is preferably disposed entirely on the bottom surface of the groove 31, but it may also be omitted from a portion of the bottom surface of the groove 31. The plurality of pillars 71B are arranged along the direction in which the groove 31 extends. Two adjacent pillars 71B are arranged at a predetermined distance. The wall 71C is arranged along the direction in which the groove 31 extends. Figure 3 As shown, the front end of the column portion 71B of the elastic portion 71 of the fuel cell unit 100A contacts the partition 40 of the fuel cell unit 100B. Although not shown, the front end of the wall portion 71C contacts the partition 40 of the fuel cell unit 100B.

[0051] As a characteristic structure of this embodiment, the elastic portions 71 and 72 are disposed in corresponding grooves 31 formed in the partition 30. The advantages of disposing the elastic portions 71 and 72 in the grooves 31 will be explained. Hereinafter, the elastic portion 71 will be described as an example, but the same applies to the elastic portion 72.

[0052] First, the flow of coolant in the flow path space WF puts pressure on the elastic parts 71 and 72. When the pressure of the coolant flow increases, the pressure applied to the elastic parts 71 and 72 also increases. In this case, the possibility of the elastic parts 71 and 72 shifting relative to the partition 30 or detaching from the partition 30 increases.

[0053] According to this embodiment, the base portion 71A, which is part of the elastic portion 71, is disposed in the groove 31 such that it covers the bottom surface of the groove 31 formed in the partition 30. Therefore, compared with the case where the base portion 71A of the elastic portion 71 is not disposed in the groove 31, the area in which the coolant directly contacts the elastic portion 71 can be reduced, and the force exerted on the elastic portion 71 by the coolant can be reduced. Therefore, the occurrence of positional displacement and peeling of the elastic portion 71 can be suppressed.

[0054] According to this embodiment, compared to a configuration where a portion of the elastic part 71, namely the base 71A, is not disposed in the groove 31, the area of ​​direct contact between the coolant and the elastic part 71 can be reduced. Therefore, the flow of coolant in the flow path space WF can be made smoother. From the viewpoint of power generation efficiency, it is preferable for the coolant to flow uniformly in the flow path space WF, but the flow of coolant may be obstructed by the elastic part 71 disposed in the flow path space WF. According to the above method, this problem can be suppressed. Therefore, the increase in pressure loss of the coolant in the flow path space WF can be suppressed. Thus, the decrease in power generation efficiency can be suppressed.

[0055] In this embodiment, the plurality of column portions 71B of the elastic portion 71 are arranged downstream of the wall portion 71C in the direction from the supply manifold Miw toward the discharge manifold Mow (see reference). Figure 1 , 5 On the supply manifold Miw side, the wall portion 71C is positioned upstream, thus not obstructing the flow of coolant. The plurality of pillar portions 72B of the elastic portion 72 are positioned upstream of the wall portion 72C in the direction from the supply manifold Miw toward the discharge manifold Mow. On the discharge manifold Mow side, the wall portion 72C is positioned downstream, thus not obstructing the flow of coolant. Therefore, the flow of coolant can be made smooth.

[0056] B. Other implementation methods:

[0057] (B1) In the above embodiment, an example of elastic part 71 having wall portion 71C was described, but elastic part 71 may also not have wall portion 71C. For example, elastic part 71 may include base portion 71A and multiple pillar portions 71B, which may be arranged to surround supply manifold Miw. The same applies to elastic part 72.

[0058] (B2) The elastic part 71 may be configured such that a portion of the column portion 71B of the elastic part 71 is adjacent to the side flat portion FA of the groove portion 31 (see reference). Figure 2 Interference. Furthermore, the elastic portion 71 can be configured such that a portion of its base 71A interferes with a side-flat portion continuous from the groove 31. The portion of the base 71A of the elastic portion 71 exposed in the flow path space WF may have irregularities. Furthermore, it can be configured such that one side of the side-flat portion on each side of the groove 31 has a different height than the other side.

[0059] (B3) In addition, unevenness may be formed on the bottom surface of the groove 31. By forming unevenness on the bottom surface of the groove 31, the base 71A and the bottom surface of the groove 31A can be firmly joined, and the suppression effect of positional displacement and peeling of the elastic part 71 is further improved. The same applies to the groove and elastic part 72 formed around the through hole 306.

[0060] This invention is not limited to the embodiments described above, and can be implemented in various configurations without departing from its spirit. For example, to address some or all of the above-described issues, the technical features of embodiments corresponding to the technical features in the various aspects described in the summary 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 omitted.

Claims

1. A fuel cell stack provided with a plurality of cell units stacked, characterized by a first cell unit among the plurality of cell units being provided with: a membrane electrode assembly; a frame holding the membrane electrode assembly; a pair of separators sandwiching the membrane electrode assembly held by the frame; and one or more elastic bodies having a base portion and a plurality of column portions protruding from the base portion, one of the pair of separators provided in the first cell unit, i.e., a first separator, being provided with one or more groove portions on a first face opposite to a face opposite to the other of the pair of separators provided in the first cell unit, the base portion of the one or more elastic bodies being disposed in the one or more groove portions, the base portion covering a bottom face of the one or more groove portions, at least a part of the plurality of column portions being disposed in a direction in which the one or more groove portions extend, a leading end of the plurality of column portions of the one or more elastic bodies disposed in the one or more groove portions of the first separator being in contact with a second separator provided in a second cell unit adjacent to the first cell unit in a flow path space of a coolant formed between the first cell unit and the second cell unit, i.e., in a gap formed by the first face of the first separator provided in the first cell unit overlapping the second separator provided in the second cell unit.

2. The fuel cell stack according to claim 1, characterized by the one or more elastic bodies including a first elastic body and a second elastic body, the first elastic body and the second elastic body each having a wall portion protruding from the base portion in addition to the base portion and the plurality of column portions, a supply manifold supplying the coolant to the flow path space and a discharge manifold discharging the coolant from the flow path space being formed on the first separator, a first groove portion of the one or more groove portions being formed on the first face of the first separator so as to surround the supply manifold, a second groove portion of the one or more groove portions being formed on the first face of the first separator so as to surround the discharge manifold, the plurality of column portions of the first elastic body being disposed at a position more downstream than the wall portion of the first elastic body in a direction from the supply manifold toward the discharge manifold by the base portion of the first elastic body being disposed in the first groove portion, the plurality of column portions of the second elastic body being disposed at a position more upstream than the wall portion of the second elastic body in the direction by the base portion of the second elastic body being disposed in the second groove portion.

3. The fuel cell stack according to claim 2, characterized by in a state in which the membrane electrode assembly held by the frame is sandwiched by the first separator and the other of the pair of separators provided in the first cell unit, a second face of the first separator opposite to the first face being in contact with the frame at a position corresponding to a back face of a position at which the one or more groove portions are provided.

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