Spacer member, and fuel cell

Abstract

This invention provides a technology that can suppress warping of fuel cells at low temperatures. [Solution] A spacer member is provided which is placed on a separator provided in a fuel cell. The spacer member is placed outside a sealing member that is placed on the separator so as to surround the periphery of an opening formed in the separator, and is sandwiched together with the sealing member between adjacent fuel cells, and has a glass transition temperature of -20°C or higher.

Description

Technical Field

[0001] The present disclosure relates to a spacer member and a fuel cell.

Background Art

[0002] Patent Document 1 discloses using a sealing member having a glass transition temperature of -40°C or lower for sealing constituent members of a fuel cell.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

SUMMARY OF THE INVENTION

Problem to be Solved by the Invention

[0004] The inventors of the present application attempted to stack a plurality of fuel cells by disposing spacer members between the fuel cells in order to suppress warpage of the fuel cells. The inventors have found that when a member having a glass transition point of around -40°C is used as the spacer member, the reaction force of the spacer member becomes insufficient at low temperatures where the warpage of separators provided in the fuel cells increases, leading to the problem that the warpage of the fuel cells cannot be suppressed.

Means for Solving the Problem

[0005] The present disclosure can be implemented in the following aspects.

[0006] (1) According to a first aspect of the present disclosure, there is provided a spacer member disposed on a separator provided in a fuel cell. This spacer member is disposed outside a sealing member arranged on the separator so as to surround the periphery of an opening formed in the separator, is sandwiched together with the sealing member between adjacent fuel cells, and has a glass transition temperature of -20°C or higher. In this configuration, the decrease in the reaction force of the spacer member at low temperatures below -20°C can be suppressed, thus suppressing warping of the fuel cell at low temperatures. (2) A second embodiment of the present disclosure provides a fuel cell comprising the spacer member and the separator having the opening formed therein and the sealing member arranged to surround the opening. (3) In the fuel cell of the above configuration, the height of the sealing member may be greater than the height of the spacer member. In this configuration, the sealing performance of the opening by the sealing member can be improved. (4) In the fuel cell of the above form, a membrane electrode assembly is provided which is positioned at a location corresponding to the central region of the separator, the opening is formed in the separator between the central region and the outer circumference of the separator, and the spacer member is disposed between the opening and the outer circumference of the separator, and does not have to be disposed between the opening and the central region. With this form, warping of the fuel cell can be suitably suppressed. (5) In the fuel cell of the above form, a plurality of spacer members may be provided, the separator may be rectangular in shape, and a plurality of openings may be formed in the separator, and each of the plurality of openings and each of the plurality of spacer members may be positioned at a location corresponding to the four corners of the separator. With such a form, warping of the entire fuel cell can be suppressed. In addition to the above-described forms such as spacer members and fuel cells, this disclosure can also be implemented, for example, as a fuel cell stack comprising multiple fuel cells, or as a method for manufacturing a fuel cell stack. [Brief explanation of the drawing]

[0007] [Figure 1] This is a perspective view showing the schematic configuration of a fuel cell stack. [Figure 2] This is a front view showing the schematic configuration of the separator. [Figure 3] This is a schematic cross-sectional view along line III-III in Figure 2. [Figure 4]This is an explanatory diagram showing a stacked configuration of fuel cells. [Figure 5] This figure shows the amount of compression of the sealing member. [Figure 6] This diagram illustrates the material of the spacer component. [Modes for carrying out the invention]

[0008] A. First Embodiment: Figure 1 is a perspective view showing the schematic configuration of a fuel cell stack 10 equipped with a fuel cell 140 as a first embodiment. Arrows are shown in Figure 1 along the mutually orthogonal X, Y, and Z directions. The X, Y, and Z directions are directions along the three mutually orthogonal spatial axes, the X, Y, and Z axes, and include both the direction along one side of the X, Y, and Z axes and the opposite direction, respectively. The X and Y axes are axes along the horizontal plane, and the Z axis is an axis along the vertical line. Arrows along the X, Y, and Z directions are also shown in other figures as appropriate. The X, Y, and Z directions in Figure 1 and the X, Y, and Z directions in the other figures represent the same directions.

[0009] The fuel cell stack 10 comprises a laminate 150 formed by stacking multiple fuel cells 140 in the Z direction, a pair of terminal plates 300, 310, a pair of insulating plates 320, 330, and a pair of end plates 340, 350. The terminal plates 300, 310 sandwich the laminate 150 in the Z direction. The insulating plates 320, 330 are positioned in contact with the terminal plates 300, 310 from the outside in the Z direction. The end plates 340, 350 are positioned in contact with the insulating plates 320, 330 from the outside in the Z direction. The fuel cell stack 10 is fastened in the Z direction by fastening members (not shown) and is held in place under fastening pressure in the Z direction. Note that stacking and fastening multiple fuel cells 140 is sometimes called stacking. Each fuel cell 140 is also called a single cell.

[0010] The fuel cell 140 in this embodiment is a polymer electrolyte fuel cell that generates electricity by receiving a hydrogen-containing anode gas and an oxygen-containing cathode gas. The electricity generated by the electrochemical reaction in the fuel cell stack 10 is collected at the terminal plates 300 and 310 and taken out to an external load from terminals provided on the terminal plates 300 and 310. The insulating plates 320 and 330 are made of insulating materials such as rubber or resin. The end plates 340 and 350 are made of metal such as stainless steel.

[0011] The fuel cell stack 10 is provided with an anode gas supply manifold 410 that supplies anode gas to each fuel cell 140, and an anode off-gas discharge manifold 415 that discharges anode off-gas from each fuel cell 140. The fuel cell stack 10 is also provided with a cathode gas supply manifold 420 that supplies cathode gas to each fuel cell 140, and a cathode off-gas discharge manifold 425 that discharges cathode off-gas from each fuel cell 140. Furthermore, the fuel cell stack 10 is provided with a refrigerant supply manifold 430 that supplies refrigerant to the refrigerant flow path between the fuel cells 140, and a refrigerant discharge manifold 435 that discharges refrigerant from the refrigerant flow path.

[0012] The anode gas supply manifold 410 penetrates the end plate 350, the insulating plate 330, the terminal plate 310, and all the stacked fuel cells 140. Similarly, the anode off-gas discharge manifold 415, the cathode gas supply manifold 420, the cathode off-gas discharge manifold 425, the refrigerant supply manifold 430, and the refrigerant discharge manifold 435 penetrate the end plate 350, the insulating plate 330, the terminal plate 310, and all the stacked fuel cells 140.

[0013] Each fuel cell 140 comprises a membrane electrode gas diffusion-layer assembly (MEGA) plate 20 and a pair of separators 40 and 50. The MEGA plate 20 has a MEGA 21 and a resin sheet 22 bonded around the MEGA 21. Separator 40 is located in the +Z direction of separator 50. Separators 40 and 50 and the MEGA plate 20 have a rectangular shape. Separators 40 and 50 have the same shape. Separator 40 is sometimes called the first separator and separator 50 is sometimes called the second separator.

[0014] MEGA21 comprises a membrane electrode assembly (MEA) and a pair of gas diffusion layers that sandwich the MEA. The MEA has an electrolyte membrane and an anode electrode catalyst layer and a cathode electrode catalyst layer arranged on both sides of the electrolyte membrane. The electrolyte membrane is a solid polymer thin film that exhibits good proton conductivity in a wet state. The electrolyte membrane is composed of, for example, a fluororesin ion exchange membrane. The catalyst layer comprises a catalyst that promotes the chemical reaction between hydrogen and oxygen and carbon particles supporting the catalyst. The gas diffusion layers are provided adjacent to the side facing the catalyst layer. The gas diffusion layers are layers that diffuse the reaction gas used in the electrode reaction along the plane direction of the electrolyte membrane and are composed of a porous diffusion layer substrate. As the diffusion layer substrate, porous substrates with conductivity and gas diffusion properties such as carbon fiber substrates, graphite fiber substrates, and foamed metals are used. The MEA is positioned in a location corresponding to the central region CA of the separators 40 and 50.

[0015] In the present embodiment, the resin sheet 22 is formed of polyethylene terephthalate (PET). In other embodiments, the resin sheet 22 may be formed of various other thermoplastic resin members such as polypropylene and polyethylene. The resin sheet 22 is provided with slit-shaped gas introduction paths (not shown) so as to communicate each manifold with the MEGA 21. Specifically, the manifolds communicated with the MEGA 21 by the gas introduction paths are an anode gas supply manifold 410, an anode off-gas discharge manifold 415, a cathode gas supply manifold 420, and a cathode off-gas discharge manifold 425.

[0016] In FIG. 1, the position of the seal portion 35 on the resin sheet 22 is indicated by a broken line. The seal portion 35 refers to a portion of the resin sheet 22 that is bonded to the separators 40 and 50. The seal portion 35 is formed so as to individually enclose each manifold when viewed along the Z direction, and seals fluid inside the fuel cell 140. The seal portion 35 is formed, for example, by heat-pressing the resin sheet 22 from above the separator 40 in a state where the separator 50, the MEGA plate 20, and the separator 40 are stacked in this order from below.

[0017] The separators 40 and 50 sandwich the MEGA plate 20. In the present embodiment, the separators 40 and 50 are formed of titanium which has conductivity and high corrosion resistance. The separators 40 and 50 may be formed of SUS.

[0018] Figure 2 is a front view showing a schematic configuration of a separator 50. Figure 3 is a schematic cross-sectional view taken along line III-III in Figure 2. A sealing member 60 is arranged on the surface of the separator 50 of the fuel cell 140. The surface of the separator 50 refers to the outer surface of the separator 50, which is the surface opposite to the surface in contact with the MEGA plate 20. The sealing member 60 is formed of, for example, rubber, a thermoplastic elastomer, a UV-curable gasket, or the like. The sealing member 60 deforms by receiving a force in the direction of being sandwiched in the Z direction when the fuel cell stack 10 described above is fastened. This deformation increases the contact area between the sealing member 60 and the separators 40, 50 that sandwich the sealing member 60, ensuring fluid sealing performance between adjacent fuel cells 140.

[0019] The sealing member 60 in the present embodiment includes a first sealing member 61 and a plurality of second sealing members 62. The first sealing member 61 surrounds a coolant supply manifold 430, a coolant discharge manifold 435, and a coolant flow path 45 defined between adjacent fuel cells 140. The second sealing members 62 are individually provided around each of the anode gas supply manifold 410, the anode off-gas discharge manifold 415, the cathode gas supply manifold 420, and the cathode off-gas discharge manifold 425. The sealing member 60 is bonded to the surface of the separator 50. The sealing member 60 is also referred to as a gasket. In other embodiments, the first sealing member 61 and the second sealing member 62 may be integrally formed.

[0020] In the separator 50, when the opening constituting the anode gas supply manifold 410, the opening constituting the anode off-gas discharge manifold 415, the opening constituting the cathode gas supply manifold 420, and the opening constituting the cathode off-gas discharge manifold 425 are collectively referred to without distinction, they are simply called openings 400. The openings 400 are arranged at positions corresponding to the four corners of the rectangular separator 50. The openings 400 are located between the central region CA and the outer periphery of the separator 50.

[0021] A spacer member 70 is positioned on the separator 50. The spacer member 70 is also called a warp-preventing member. The spacer member 70 is positioned outside the seal member 60 provided around the opening 400 formed in the separator 50. In this embodiment, the spacer member 70 is positioned outside the second seal member 62 provided around the opening 400. That is, on the separator 50, the opening 400 is located inside the second seal member 62, and the spacer member 70 is located outside the second seal member 62. The spacer member 70 has a substantially rectangular parallelepiped shape. The spacer member 70 is formed from, for example, rubber, thermoplastic elastomer, UV-curable gasket, etc. The spacer member 70 is bonded to the surface of the separator 50, similar to the seal member 60. As shown in Figure 3, when the fuel cell 140 is not stacked, the height of the seal member 60 from the surface of the separator 50 is higher than the height of the spacer member 70. In other words, the height of the spacer member 70 is lower than the height of the seal member 60. The spacer member 70, together with the seal member 60, is sandwiched between adjacent fuel cells 140.

[0022] Figure 4 is an explanatory diagram showing the state in which the fuel cells 140 are stacked. In the manufacturing process for producing the fuel cells 140, when the MEGA plate 20 is sandwiched between separators 40 and 50 and joined by heating press, the fuel cells 140 may warp so that they are convex toward the anode side. In other words, the fuel cells 140 may warp so that the ends of the fuel cells 140 are curved toward the cathode side. This is due to the effect of springback that occurs during the press molding of separators 40 and 50. Figure 4 shows the state in which the fuel cells 140 warped so as to be convex toward the anode side are stacked. When fuel cells 140 warped so as to be convex toward the anode side are stacked, the gap between fuel cells 140 located on the total negative electrode side becomes larger, and the amount of compression of the sealing member 60 becomes insufficient, which may cause gas leakage between the fuel cells 140.

[0023] Figure 5 illustrates the compression amount of the sealing member 60 provided on a fuel cell 140 that does not have a spacer member 70. As shown in Figure 5, the compression amount u (mm) of the sealing member 60 on the total negative electrode side decreases by an unequal pitch of nf / k (mm), where f (N) is the warping force of the fuel cell 140 and k (N / mm) is the spring constant of the sealing member 60 (n is the number of stacked fuel cells 140). When the compression amount of the sealing member 60 decreases, the clearance between the fuel cells 140 widens. Warping force refers to the force that tries to return a warped fuel cell 140 to its original shape when it is flattened, that is, the force that tries to warp it. The warping force can be measured by using a push-pull gauge after pressing the fuel cell 140 until it is flat.

[0024] Therefore, in this embodiment, the spacer members 70 are positioned at the four corners of the separator 50 so as to correspond to each of the openings 400 formed at the four corners of the separator 50. As a result, each of the four corners of the fuel cells 140 contacts the spacer members 70, so even if the fuel cells 140 are warped, the warping is corrected during stacking, and the widening of the pitch between the fuel cells 140 can be suppressed. When stacking the fuel cells 140, the compression pressure is adjusted so that not only the seal member 60 but also the spacer members 70 are compressed. With the seal member 60 and the spacer members 70 positioned between the fuel cells 140, the spring constant k shown in Figure 5 becomes the sum of the spring constant k1 of the seal member 60 and the spring constant k2 of the spacer member 70 (k = k1 + k2). As a result, even if the warping force of the fuel cells 140 is the same, the spring constant increases, which reduces the unequal pitch (nf / k) shown in Figure 5, and suppresses the widening of the clearance between the fuel cells 140. The area of ​​the spacer member 70 is determined by calculating the required rigidity of the spacer member 70 and then calculating the area that can secure that rigidity.

[0025] Figure 6 illustrates the material of the spacer member 70. In this embodiment, the spacer member 70 is formed using a material with a glass transition temperature of -20°C or higher. As such a material, a UV-curable gasket called CIPG (Cured In Place Gasket) can be used. The operating temperature range of the fuel cell 140 in this embodiment is approximately -30°C to approximately 100°C. The operating temperature range is the temperature range of the external environment that guarantees the normal operation of the fuel cell 140. In this embodiment, the glass transition temperature of the spacer member 70 is higher than the minimum operating temperature range of the fuel cell 140. Preferably, the glass transition temperature of the spacer member 70 is 5°C or more higher than the minimum operating temperature range of the fuel cell 140. In this embodiment, the glass transition temperature of the spacer member 70 is -20°C, which is 10°C higher than the minimum operating temperature range of the fuel cell 140. It is preferable that the glass transition temperature of the spacer member 70 be lower than 0°C, and more preferably lower than -10°C.

[0026] It is known that separators 40 and 50, made of titanium or SUS, have a higher Young's modulus and higher rigidity at lower temperatures. Therefore, the warping force of the fuel cell 140 increases at lower temperatures. As a result, the unequal pitch described above increases at lower temperatures. In contrast, in this embodiment, the glass transition temperature of the spacer member 70 is set to -20°C, which is higher than the minimum operating guarantee temperature of the fuel cell 140. This makes the spacer member 70 harder at low temperatures near the minimum operating guarantee temperature. As a result, the rigidity of the spacer member 70 increases at low temperatures, and the reaction force increases, which suppresses the widening of the gap between the fuel cells 140.

[0027] In the embodiment described above, a spacer member 70 having a glass transition temperature of -20°C or higher is sandwiched between adjacent fuel cells 140 together with a sealing member 60. Therefore, at low temperatures where the warping force of the fuel cells 140 is large, the reaction force of the spacer member 70 increases, suppressing the warping of the fuel cells 140. As a result, gas leakage from between the fuel cells 140 caused by the warping of the fuel cells 140 can be suppressed at low temperatures.

[0028] Furthermore, in this embodiment, since the height of the sealing member 60 on the separator 50 is greater than the height of the spacer member 70, the amount of compression of the sealing member 60 can be increased. Therefore, the gas sealing performance of the sealing member 60 can be improved.

[0029] Furthermore, in this embodiment, the spacer member 70 is positioned between the opening 400 of the separator 50 and the outer circumference of the separator 50, and is not positioned between the opening 400 of the separator 50 and the central region CA. Therefore, warping at the ends of the fuel cell 140 can be effectively suppressed.

[0030] Furthermore, in this embodiment, each of the multiple openings 400 and each of the multiple spacer members 70 are positioned at locations corresponding to the four corners of the rectangular separator 50. Therefore, warping of the entire fuel cell 140 can be suppressed.

[0031] B. Other embodiments: (B1) In the above embodiment, the height of the sealing member 60 placed on the separator 50 is higher than the height of the spacer member 70. In contrast, the height of the sealing member 60 may be the same as or lower than the height of the spacer member 70.

[0032] (B2) In the above embodiment, the spacer member 70 is not placed between the opening 400 of the separator 50 and the central region CA. In contrast, the spacer member 70 may be placed between the opening 400 of the separator 50 and the central region CA.

[0033] (B3) In the above embodiment, the spacer members 70 are positioned at locations corresponding to the four corners of the separator 50. In contrast, the spacer members 70 may also be positioned at locations other than the four corners of the separator 50.

[0034] (B4) In the above embodiment, the sealing member 60 and the spacer member 70 are bonded to the separator 50. Alternatively, the sealing member 60 and the spacer member 70 may be bonded to the separator 40. Alternatively, one of the sealing member 60 and the spacer member 70 may be bonded to the separator 50 and the other to the separator 40.

[0035] (B5) In the above embodiment, an example was described in which the fuel cell 140 warps so that it is convex toward the total negative electrode side. However, due to the effect of springback caused by the press molding of the separators 40 and 50, the fuel cell 140 may also warp so that it is convex toward the total positive electrode side. Even in this case, it is possible to suppress the warping of the fuel cell 140 by arranging the spacer member 70 as in the above embodiment.

[0036] (B6) In the above embodiment, the shape of the spacer member 70 is substantially rectangular parallelepiped. The shape of the spacer member 70 is not limited to this, and for example, it may be substantially cylindrical or L-shaped when viewed from above.

[0037] (B7) This disclosure is not limited to solid polymer electrolyte fuel cells, but is broadly applicable to fuel cells of the type in which a fuel cell stack is formed by stacking multiple fuel cells.

[0038] This disclosure is not limited to the embodiments described above, and can be implemented in various configurations without departing from its spirit. For example, the technical features in the embodiments corresponding to the technical features in each form described in the summary of the invention can be replaced or combined as appropriate in order to solve some or all of the above-described problems, or to achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be deleted as appropriate. [Explanation of Symbols]

[0039] 10…Fuel cell stack, 20…MEGA plate, 21…MEGA, 22…Resin sheet, 35…Seal section, 40…Separator, 45…Refrigerant flow path, 50…Separator, 60…Sealing member, 61…First sealing member, 62…Second sealing member, 70…Spacer member, 140…Fuel cell, 150…Laminate, 300,310…Terminal plate, 320,330…Insulating plate, 340,350…End plate, 400…Opening, 410…Anode gas supply manifold, 415…Anode off-gas discharge manifold, 420…Cathode gas supply manifold, 425…Cathode off-gas discharge manifold, 430…Refrigerant supply manifold, 435…Refrigerant discharge manifold, CA…Central region

Claims

1. A spacer member that is placed on a separator provided in a fuel cell, The sealing member is positioned on the separator so as to surround the periphery of the opening formed in the separator, and is positioned on the outside of the sealing member that is placed on the separator. It is sandwiched between adjacent fuel cells together with the sealing member, The glass transition temperature is -20°C or higher. Spacer component.

2. The spacer member according to claim 1, The separator having the aforementioned opening formed and the sealing member arranged to surround the periphery of the opening, A fuel cell equipped with a fuel cell.

3. A fuel cell according to claim 2, A fuel cell in which the height of the sealing member is greater than the height of the spacer member.

4. A fuel cell according to claim 2, The separator comprises a membrane electrode assembly positioned at a location corresponding to the central region of the separator, The opening is formed in the separator between the central region and the outer circumference of the separator. A fuel cell in which the spacer member is disposed between the opening and the outer circumference of the separator, and is not disposed between the opening and the central region.

5. A fuel cell according to claim 4, The spacer members comprise a plurality of the aforementioned spacer members, The separator is rectangular in shape, The separator has a plurality of openings formed therein. A fuel cell in which each of the multiple openings and each of the multiple spacer members are positioned at locations corresponding to the four corners of the separator.

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