Fuel cell, and method for manufacturing a fuel cell

Abstract

This technology provides a way to suppress the deterioration of sealing performance. [Solution] The fuel cell cell comprises an anode separator and a cathode separator having a coating on their surface, and each of the anode separator and cathode separator comprises a main body, a coolant manifold which is an opening formed in the main body and through which coolant flows, an internal cell seal portion which seals the space between the anode separator and the cathode separator inside the fuel cell by the main body being bonded to an insulating sheet so as to surround the coolant manifold, and a sacrificial galvanic corrosion portion which is disposed between the coolant manifold and the internal cell seal portion and has a plurality of exposed portions in which the substrate is exposed without being covered by a coating, and the sacrificial galvanic corrosion portion has at least one exposed portion on a straight line connecting the coolant manifold and the internal cell seal portion.

Description

Technical Field

[0001] The present disclosure relates to a fuel cell, and a method for manufacturing a fuel cell.

Background Art

[0002] Conventionally, a fuel cell having an anode separator and a cathode separator that sandwich a membrane electrode gas diffusion layer assembly and an insulating sheet that holds the outer peripheral portion of the membrane electrode gas diffusion layer assembly is known (Patent Document 1). In this fuel cell, each separator has a coolant manifold through which a coolant flows, and a seal portion that seals between the anode separator and the cathode separator by being adhered to the insulating sheet. Further, each separator has a sacrificial corrosion portion that is disposed without being adhered to the insulating sheet between the coolant manifold and the seal portion. By preferentially corroding this sacrificial corrosion portion rather than the seal portion, the seal portion is protected.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In order to improve functions such as corrosion resistance, a separator having a corrosion-resistant coating on its surface may be manufactured by treating the surface of the separator substrate. In this case, the separator may be molded by pressing the substrate whose surface is covered with the coating. In this case, a part of the coating may be broken by the pressing process, and the substrate may be partially exposed. If the coating covering the seal portion is broken, corrosion may progress from the broken part of the coating, resulting in the generation of pinholes in the seal portion and a possible decrease in the sealing performance.

Means for Solving the Problems

[0005] This disclosure can be implemented in the following forms:

[0006] (1) According to one embodiment of the present disclosure, a fuel cell is provided. The fuel cell comprises a plate member having a membrane electrode gas diffusion layer assembly and an insulating sheet holding the outer periphery of the membrane electrode gas diffusion layer assembly, and an anode separator and a cathode separator sandwiching the plate member, the anode separator and the cathode separator having a coating on their surface, wherein the anode separator and the cathode separator each comprise a main body, a coolant manifold as an opening formed in the main body for circulating coolant, an internal cell seal portion that seals the space between the anode separator and the cathode separator within the fuel cell by the main body being bonded to the insulating sheet so as to surround the coolant manifold, and a sacrificial galvanic corrosion portion disposed between the coolant manifold and the internal cell seal portion, having a plurality of exposed portions in which the substrate is exposed without being covered by the coating, the sacrificial galvanic corrosion portion having at least one of the exposed portions on a straight line connecting the coolant manifold and the internal cell seal portion. In this configuration, even when the surface is covered with a coating, the sacrificial corrosion area has a larger exposed area than other parts, allowing for preferential corrosion of the sacrificial corrosion area. This suppresses the formation of pinholes in the cell's internal seal area, thus preventing a decrease in sealing performance. (2) In the above configuration, the sacrificial corrosion portion may have exposed portions on two or more concentric circles centered on the coolant manifold. This configuration allows the sacrificial corrosion portion to be subjected to electrolytic corrosion more reliably and preferentially than other parts. This makes it possible to more reliably suppress the occurrence of pinholes in the cell seal portion. Thus, it is possible to more reliably suppress a decrease in sealing performance. (3) In the above configuration, the sacrificial galvanic corrosion portion may have a plurality of exposed portions spaced at intervals of 10 μm or less. This configuration allows the sacrificial galvanic corrosion portion to be galvanized more reliably and preferentially than other parts. This makes it possible to more reliably suppress the occurrence of pinholes in the cell seal portion. Therefore, it is possible to more reliably suppress a decrease in sealing performance. (4) According to another embodiment of the present disclosure, a method for manufacturing a fuel cell is provided. The method for manufacturing a fuel cell includes: a plate preparation step of preparing a plate member having (1a) a membrane electrode gas diffusion layer assembly and (1b) an insulating sheet holding the outer periphery of the membrane electrode gas diffusion layer assembly; a substrate preparation step of preparing a substrate for an anode separator and a cathode separator having (2a) a main body, (2b) a coolant manifold as an opening formed in the main body for circulating coolant, and (2c) an embossed portion disposed near the coolant manifold, the embossed portion having a plurality of protrusions protruding from the main body; a surface treatment step of treating the surface of the substrate to form a film on the surface of the substrate; and pressing the substrate on which the film has been formed. The invention comprises a molding step of forming the anode separator and the cathode separator into predetermined shapes by processing, and an internal cell seal portion forming step of forming an internal cell seal portion that seals the space between the anode separator and the cathode separator within the fuel cell by bonding the insulating sheet to the main body so as to surround the coolant manifold while the plate member is sandwiched between the anode separator and the cathode separator, wherein the molding step includes an exposure step of stretching the protrusions using the external force applied by the press work and rupturing the coating on the protrusions, thereby forming a sacrificial galvanic corrosion portion having a plurality of exposed portions in which the base material is exposed without being covered by the coating. According to this embodiment, a separator can be manufactured using a base material whose surface is covered with a coating and which has an embossed portion having a plurality of protrusions between the coolant manifold and the internal cell seal portion. In this way, when forming a separator by press-forming a substrate whose surface is covered with a coating, the external force applied by the press-forming process can be used to stretch the multiple protrusions formed on the substrate. This causes the coating on the protrusions to break, thereby forming a sacrificial corrosion area with multiple exposed portions between the coolant manifold and the cell's internal seal. (5) In the above configuration, the projection may protrude from the side of the main body facing the insulating sheet to the side opposite to the facing surface. In this configuration, when a coolant flow path is formed between the anode separator and cathode separator of adjacent fuel cell cells by stacking multiple fuel cell cells, the cross-sectional area of ​​the coolant flow path can be increased. This reduces the pressure loss when the coolant flows. This disclosure can be implemented in various forms other than the fuel cell and the manufacturing method of the fuel cell described above. For example, it can be implemented in the form of a fuel cell stack formed by stacking multiple fuel cell cells, or a vehicle equipped with fuel cell cells. [Brief explanation of the drawing]

[0007] [Figure 1] A diagram showing the schematic configuration of a fuel cell stack. [Figure 2] A flowchart illustrating the manufacturing method of a fuel cell. [Figure 3] This diagram shows an example of how the cooling surface of a separator looks when observed. [Figure 4] A diagram showing the detailed configuration of the substrate. [Figure 5] A diagram showing the detailed structure of the protrusions. [Figure 6] A diagram showing the direction of projection. [Figure 7] This figure shows the verification results regarding the spacing of exposed areas in the sacrificial galvanic corrosion zone. [Modes for carrying out the invention]

[0008] A. First Embodiment: Figure 1 shows a schematic configuration of a fuel cell stack 1. The fuel cell stack 1 generates electricity through an electrochemical reaction by receiving a fuel gas such as hydrogen and an oxidizer gas such as air. The fuel cell stack 1 has a stack structure in which multiple fuel cell cells 100 are stacked.

[0009] Each of the multiple fuel cell cells 100 includes a plate member 10. The plate member 10 comprises a membrane electrode gas diffusion layer assembly 11 (MEGA) and an insulating sheet 12.

[0010] The membrane electrode gas diffusion layer assembly 11 includes a membrane electrode assembly (MEA) 110. The membrane electrode assembly 110 includes 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 permeates specific ions. The anode catalyst layer 112 catalyzes an electrochemical reaction on the anode side. The cathode catalyst layer 113 catalyzes an electrochemical reaction on the cathode side. The membrane electrode gas diffusion layer assembly 11 further includes an anode gas diffusion layer 118 disposed opposite the anode catalyst layer 112, and a cathode gas diffusion layer 119 disposed opposite 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 the oxidizing gas and supplies it to the cathode catalyst layer 113.

[0011] The insulating sheet 12 has an opening 13 in the center. The insulating sheet 12 is a rectangular frame. The outer periphery 11r of the membrane electrode gas diffusion layer assembly 11 is bonded to the opening 13 of the insulating sheet 12 with adhesive. In this way, the insulating sheet 12 holds the outer periphery 11r of the membrane electrode gas diffusion layer assembly 11.

[0012] Furthermore, each of the multiple fuel cell cells 100 is equipped with an anode separator 20 and a cathode separator 30 that sandwich the plate member 10. The anode separator 20 is positioned to face the anode gas diffusion layer 118. The cathode separator 30 is positioned to face the cathode gas diffusion layer 119. Each separator 20, 30 separates the plate member 10 from other fuel cell cells 100. Each separator 20, 30 has gas surfaces 20g, 30g and cooling surfaces 20c, 30c. The gas surfaces 20g, 30g are surfaces that come into contact with either the fuel gas or the oxidizer gas. The cooling surfaces 20c, 30c are surfaces that come into contact with the coolant and are opposite to the gas surfaces 20g, 30g. In this embodiment, the gas surfaces 20g, 30g are surfaces that come into contact with the insulating sheet 12. The cooling surfaces 20c and 30c are the surfaces facing other fuel cell cells 100.

[0013] The insulating sheet 12 and each separator 20, 30 each have manifolds 41-46 for fluid flow. The manifolds 41-46 are openings formed in the main bodies 21, 31 of the insulating sheet 12 and each separator 20, 30. Each manifold 41-46 is formed at a position where it overlaps with the others in the stacking direction DL of the multiple fuel cell cells 100. This distributes the fuel gas to the anode side of the fuel cell cells 100, the oxidizer gas to the cathode side of the fuel cell cells 100, and the coolant between adjacent fuel cell cells 100. Specifically, the fuel gas is supplied to the fuel gas introduction manifold 44. The fuel gas supplied to the fuel gas introduction manifold 44 is distributed to the anode side of each fuel cell cell 100 and flows through the fuel gas flow path 47 formed between the plate member 10 and the gas surface 20g of the anode separator 20. Of the fuel gas distributed to the anode side, the fuel gas not used for power generation is discharged to the outside of the fuel cell stack 1 from the fuel gas outlet manifold 43. The fuel gas discharged to the outside of the fuel cell stack 1 is supplied again to the fuel gas inlet manifold 44. Oxidizer gas is supplied to the oxidizer gas inlet manifold 41. The oxidizer gas supplied to the oxidizer gas inlet manifold 41 is distributed to the cathode side of each fuel cell cell 100 and flows through the oxidizer gas flow path 48 formed between the plate member 10 and the gas surface 30g of the cathode separator 30. Of the oxidizer gas distributed to the cathode side, the oxidizer gas not used for power generation is discharged to the outside of the fuel cell stack 1 from the oxidizer gas outlet manifold 46. The oxidizer gas discharged to the outside of the fuel cell stack 1 is supplied again to the oxidizer gas inlet manifold 41. Coolant for cooling the fuel cell cells 100 is supplied to the coolant inlet manifold 42. The coolant supplied to the coolant introduction manifold 42 is distributed between adjacent fuel cell cells 100 in the stacking direction DL, and flows through a coolant flow path 49 formed between the cooling surface 20c of the anode separator 20 and the cooling surface 30c of the cathode separator 30 of adjacent fuel cell cells 100. The coolant that has flowed between adjacent fuel cell cells 100 is discharged to the outside of the fuel cell stack 1 from the coolant discharge manifold 45.The coolant discharged from the fuel cell stack 1 is supplied back to the coolant intake manifold 42.

[0014] Each separator 20, 30 has a coating FL on its surface to improve functions such as corrosion resistance. Each separator 20, 30 comprises a main body 21, 31, a manifold 41-46, a protruding part 22, 32, a gasket 51-55, rib parts 24, 25, 34, 35, cell seal parts 26a-26e, 36a-36e, and sacrificial galvanic corrosion parts 28, 29, 38, 39.

[0015] The protrusions 22 and 32 extend from the main body portions 21 and 31 so as to be spaced apart from adjacent fuel cell cells 100 along the stacking direction DL. The protrusions 22 and 32 are formed by bending each separator 20 and 30 by press working. The protrusion 22 of the anode separator 20 and the protrusion 32 of the cathode separator 30 are formed in positions that overlap each other along the stacking direction DL. As a result, the protrusions 22 and 32 form a fuel gas flow path 47 between the plate member 10 and the anode separator 20, and an oxidizer gas flow path 48 between the plate member 10 and the cathode separator 30. The protrusions 22 and 32 form a coolant flow path 49 between the anode separator 20 and the cathode separator 30 of adjacent fuel cell cells 100.

[0016] Gaskets 51-55 seal between adjacent fuel cell 100. In this embodiment, gaskets 51-55 are fixed to the cooling surfaces 20c, 30c of each separator 20, 30 by an adhesive or the like. Gaskets 51-55 are provided according to the arrangements of manifolds 41-46 and flow paths 47-49. Specifically, the first gasket 51 is arranged so as to surround the coolant manifolds 42, 45 and the coolant flow path 49 with a space from the coolant manifolds 42, 45. The first gasket 51 is an inter-cell seal part for discharging the coolant supplied to the coolant introduction manifold 42 to the coolant discharge manifold 45 without leaking the coolant outside the coolant flow path 49. The second gasket 52 is arranged so as to surround the oxidant gas introduction manifold 41. The second gasket 52 is an inter-cell seal part for preventing the oxidant gas flowing through the oxidant gas introduction manifold 41 from leaking to the coolant flow path 49 side. The third gasket 53 is arranged so as to surround the oxidant gas discharge manifold 46. The third gasket 53 is an inter-cell seal part for preventing the oxidant gas flowing through the oxidant gas discharge manifold 46 from leaking to the coolant flow path 49 side. The fourth gasket 54 is arranged so as to surround the fuel gas introduction manifold 44. The fourth gasket 54 is an inter-cell seal part for preventing the fuel gas flowing through the fuel gas introduction manifold 44 from leaking to the coolant flow path 49 side. The fifth gasket 55 is arranged so as to surround the fuel gas discharge manifold 43. The fifth gasket 55 is an inter-cell seal part for preventing the fuel gas flowing through the fuel gas discharge manifold 43 from leaking to the coolant flow path 49 side.

[0017] The rib portions 24, 25, 34, and 35 restrict the flow of coolant from the coolant manifolds 42 and 45 toward the first gasket 51, thereby suppressing galvanic corrosion between the coolant manifolds 42 and 45 and the first gasket 51. The rib portions 24, 25, 34, and 35 protrude from the main body portions 21 and 31 on the cooling surfaces 20c and 30c. The rib portions 24, 25, 34, and 35 are provided for the coolant inlet manifold 42 and the coolant outlet manifold 45, respectively. Specifically, the inlet-side rib portions 24 and 34 are formed between the first gasket 51 and the coolant inlet manifold 42. The outlet-side rib portions 25 and 35 are formed between the first gasket 51 and the coolant outlet manifold 45.

[0018] The cell seal portions 26a-26e and 36a-36e seal the space between the anode separator 20 and the cathode separator 30 within the fuel cell cell 100. The cell seal portions 26a-26e and 36a-36e are formed by bonding the main body portions 21 and 31 to predetermined sealing positions SP on the insulating sheet 12. In this embodiment, the cell seal portions 26a-26e and 36a-36e are formed on the gas surfaces 20g and 30g at positions that overlap with a portion of the first gasket 51 when each separator 20 and 30 is viewed along the stacking direction DL. The cell seal portions 26a-26e and 36a-36e are formed according to the arrangement of the manifolds 41-46 and the flow paths 47-49. Furthermore, the cell internal sealing portions 26a-26e and 36a-36e may be formed on the outward side of the first gasket 51 when the separators 20 and 30 are viewed through along the stacking direction DL within the gas surfaces 20g and 30g.

[0019] Specifically, the first in-cell seal portion 26a in the anode separator 20 is formed so as to surround the coolant introduction manifold 42. The first in-cell seal portion 26a in the anode separator 20 is an in-cell seal portion for preventing the coolant flowing through the coolant introduction manifold 42 from leaking to the fuel gas flow path 47 side. The second in-cell seal portion 26b in the anode separator 20 is formed so as to surround the coolant discharge manifold 45. The second in-cell seal portion 26b in the anode separator 20 is an in-cell seal portion for preventing the coolant flowing through the coolant discharge manifold 45 from leaking to the fuel gas flow path 47 side. The third in-cell seal portion 26c in the anode separator 20 is formed so as to surround the fuel gas manifolds 43 and 44 and the fuel gas flow path 47. The third in-cell seal portion 26c in the anode separator 20 is an in-cell seal portion for discharging the fuel gas supplied to the fuel gas introduction manifold 44 from the fuel gas discharge manifold 43 without leaking the fuel gas outside the fuel gas flow path 47. The fourth in-cell seal portion 26d in the anode separator 20 is formed so as to surround the oxidant gas introduction manifold 41. The fourth in-cell seal portion 26d in the anode separator 20 is an in-cell seal portion for preventing the oxidant gas flowing through the oxidant gas introduction manifold 41 from leaking to the fuel gas flow path 47 side. The fifth in-cell seal portion 26e in the anode separator 20 is formed so as to surround the oxidant gas discharge manifold 46. The fifth in-cell seal portion 26e in the anode separator 20 is an in-cell seal portion for preventing the oxidant gas flowing through the oxidant gas discharge manifold 46 from leaking to the fuel gas flow path 47 side.

[0020] The first cell seal portion 36a in the cathode separator 30 is formed to surround the coolant introduction manifold 42. The first cell seal portion 36a in the cathode separator 30 is a cell seal portion that prevents the coolant flowing through the coolant introduction manifold 42 from leaking to the oxidizer gas flow path 48. The second cell seal portion 36b in the cathode separator 30 is formed to surround the coolant discharge manifold 45. The second cell seal portion 36b in the cathode separator 30 is a cell seal portion that prevents the coolant flowing through the coolant discharge manifold 45 from leaking to the oxidizer gas flow path 48. The third cell seal portion 36c in the cathode separator 30 is formed to surround the oxidizer gas manifolds 41, 46 and the oxidizer gas flow path 48. The third cell seal portion 36c in the cathode separator 30 is a cell seal portion that prevents the oxidizer gas supplied to the oxidizer gas introduction manifold 41 from leaking out of the oxidizer gas flow path 48 and allows it to be discharged from the oxidizer gas outlet manifold 46. The fourth cell seal portion 36d in the cathode separator 30 is formed to surround the fuel gas introduction manifold 44. The fourth cell seal portion 36d in the cathode separator 30 is a cell seal portion that prevents the fuel gas flowing through the fuel gas introduction manifold 44 from leaking to the oxidizer gas flow path 48. The fifth cell seal portion 36e in the cathode separator 30 is formed to surround the fuel gas outlet manifold 43. The fifth cell seal portion 36e in the cathode separator 30 is a cell seal portion that prevents the fuel gas flowing through the fuel gas outlet manifold 43 from leaking to the oxidizer gas flow path 48.

[0021] The sacrificial corrosion sections 28, 29, 38, and 39 are parts of the cooling surfaces 20c and 30c of each separator 20 and 30 that are subjected to electrolytic corrosion preferentially over other parts other than the sacrificial corrosion sections 28, 29, 38, and 39. The sacrificial corrosion sections 28, 29, 38, and 39 are provided for the coolant introduction manifold 42 and the coolant outlet manifold 45, respectively. Specifically, the introduction-side sacrificial corrosion sections 28 and 38 are located between the coolant introduction manifold 42 and the cell internal seal sections 26a, 26b, 36a, and 36b. In other words, the introduction-side sacrificial corrosion sections 28 and 38 are located in the coolant introduction region IA, which extends from the coolant introduction manifold 42 towards the membrane electrode gas diffusion layer assembly 11. The outlet-side sacrificial corrosion sections 29 and 39 are located between the coolant outlet manifold 45 and the second cell internal seal sections 26b and 36b. In other words, the sacrificial corrosion sections 29 and 39 on the outlet side are located in the coolant outlet region OA, which extends from the membrane electrode gas diffusion layer assembly 11 side toward the coolant outlet manifold 45.

[0022] Figure 2 is a flowchart showing the manufacturing method of the fuel cell cell 100. Each separator 20, 30 is manufactured, for example, by cutting a roll-shaped base material BM and forming it into a predetermined shape by press working. Therefore, if the surface of the base material BM is treated after press working, it is necessary to treat the surface of each cut base material BM individually, which increases manufacturing costs. On the other hand, if the surface of the base material BM is treated before press working, the surface of the roll-shaped base material BM can be treated all at once, thus reducing manufacturing costs. Therefore, in this embodiment, each separator 20, 30 is manufactured by the following manufacturing method.

[0023] In step S1, a plate preparation step is performed to prepare the plate member 10. In step S2, a base material preparation step is performed to prepare the base material BM. In step S3, a surface treatment step is performed to treat the surface of the base material BM and form a coating FL on the surface of the base material BM. In step S4, a molding step is performed to form the anode separator 20 and cathode separator 30 into predetermined shapes by press working on the base material BM on which the coating FL has been formed. In step S5, an internal cell seal portion formation step is performed to form internal cell seal portions 26a-26e and 36a-36e. In the internal cell seal portion formation step, with the plate member 10 sandwiched between the anode separator 20 and cathode separator 30, the predetermined seal positions SP of the insulating sheet 12 are bonded to the main body portions 21 and 31. At this time, each separator 20, 30 and the insulating sheet 12 may be bonded by pressure or by adhesive.

[0024] Even in separators 20 and 30 whose surfaces are covered with a coating FL, the inventors of the present invention conceived the following in order to prioritize the electrochemical corrosion of sacrificial corrosion areas 28, 29, 38, and 39 located in the coolant inlet / outlet regions IA and OA over other parts. The inventors of the present invention conceived the idea of ​​deliberately exposing the base material BM by not performing surface treatment on the coolant inlet / outlet regions IA and OA of the cooling surfaces 20c and 30c of separators 20 and 30, where the sacrificial corrosion areas 28, 29, 38, and 39 are to be formed. Therefore, in the aforementioned surface treatment process, the inventors of the present invention attached masking members to the coolant inlet / outlet regions IA and OA to mask the coolant inlet / outlet regions IA and OA. In this state, the inventors of the present invention processed the surface of the base material BM to manufacture a separator (not shown) in which the coolant inlet / outlet regions IA and OA were not covered with the coating FL, while other parts were covered with the coating FL. In the separators manufactured in this manner, electrolytic corrosion occurred sequentially from the coolant manifolds 42 and 45 towards the cell seal portions 26a, 26b, 36a, and 36b. This protected the cell seal portions 26a, 26b, 36a, and 36b. However, this manufacturing method using a mask member not only required time to remove the mask member from the separator, but also required periodic removal of the coating FL attached to the mask member, which increased the manufacturing cost of the separator. Therefore, in order to reduce manufacturing costs, the inventors of this application manufactured separators 20v and 30v as reference examples shown below by uniformly treating the entire surface of the substrate BM without masking the coolant inlet and outlet regions IA and OA.

[0025] Figure 3 shows the observation of the cooling surfaces 20c and 30c of separators 20v and 30v as a reference example. The coolant inlet and outlet regions IA and OA are covered with the coating FL. Therefore, sufficient corrosion prevention current is not generated in the coolant inlet and outlet regions IA and OA. Furthermore, when press working is performed, the substrate BM stretches when an external force is applied to separators 20v and 30v. Then, slip occurs at the grain boundaries of the substrate BM, increasing the surface area of ​​the substrate BM. As a result, the coating FL is stretched, and in some cases, a part of the coating FL may break, exposing the substrate BM in part. As a result, separators 20v and 30v are not sequentially galvanically corroded from the coolant manifolds 42 and 45 toward the cell seal portions 26a, 26b, 36a, and 36b, but rather the galvanically corroded concentrated in the area where the coating FL has broken. Therefore, if the coating FL covering the cell seal portions 26a, 26b, 36a, and 36b is fractured, electrolytic corrosion will progress from the fractured portion of the coating FL, potentially causing pinhole PH to form in the cell seal portions 26a, 26b, 36a, and 36b, and reducing the sealing performance. In fact, multiple pinhole PH were observed on the cooling surfaces 20c and 30c of separators 20v and 30v used as reference examples. Thus, a technique is needed to suppress the formation of pinhole PH in the cell seal portions 26a, 26b, 36a, and 36b when press-forming a substrate BM whose surface is covered with a coating FL. Based on the above, the inventors of the present invention have come up with the following manufacturing method that can suppress the formation of pinhole PH in the cell seal portions 26a, 26b, 36a, and 36b by utilizing the external force applied by press-forming.

[0026] Figure 4 shows the detailed configuration of the base material BM. In Figure 4, the coolant inlet / outlet regions IA and OA of the base material BM are schematically shown as viewed from the cooling surfaces 20c and 30c. In the base material preparation process described above, the inventors of the present invention prepared a base material BM having main body portions 21 and 31, coolant manifolds 42 and 45, a first gasket 51, rib portions 24, 25, 34 and 35, cell seal portions 26a, 26b, 36a and 36b, and an embossed portion 60.

[0027] The embossed portion 60 is positioned to form sacrificial corrosion portions 28, 29, 38, 39, i.e., near the coolant manifolds 42, 45. More specifically, the embossed portion 60 is positioned between the coolant manifolds 42, 45 and the cell seal portions 26a, 26b, 36a, 36b. The embossed portion 60 has a plurality of protrusions 601-616 projecting from the main body portions 21, 31. More specifically, the embossed portion 60 has at least one protrusion 601-616 on a straight line L1-L16 connecting any points PM1-PM16 on the coolant manifolds 42, 45 and any points PS1-PS16 on the cell seal portions 26a, 26b, 36a, 36b. Furthermore, in this embodiment, the embossed portion 60 has protrusions 601-616 on two or more concentric circles C1, C2 centered on the coolant manifolds 42, 45. The shape of the protrusions 601-616 is, for example, elliptical.

[0028] Figure 5 shows the detailed configuration of projections 601-616. The connection portion 650 between projections 601-616 and the main body portions 21 and 31 has a predetermined radius of curvature. In other words, the shape of projections 601-616 has an elongation rate greater than or equal to a predetermined value between the starting point ST of projection 601-616 and the ending point EN of projection 601-616.

[0029] Figure 6 shows the direction of projection of the protrusions 601-616. As shown in the left figure of Figure 6, in this embodiment, in both the anode separator 20 and the cathode separator 30, the protrusions 601-616 protrude from the gas surface 20g,30g side to the cooling surface 20c,30c side of the main body portions 21,31. However, as shown in the center and right figures of Figure 6, in at least one of the anode separator 20 and the cathode separator 30, the protrusions 601-616 may protrude from the cooling surface 20c,30c side to the gas surface 20g,30g side of the main body portions 21,31.

[0030] Next, the inventor of the present invention used the external force applied by press working in the molding process described above to stretch the protrusions 601-616 and intentionally fractured the coating FL on the protrusions 601-616. As a result, the inventor of the present invention manufactured separators 20 and 30 having sacrificial galvanic corrosion portions 28, 29, 38, and 390, which are exposed portions 280, 290, 380, and 390 of the base material BM that are not covered by the coating FL, as shown in Figure 1. In the separators 20 and 30 manufactured in this way, it was possible to form more exposed portions 280, 290, 380, and 390 in the sacrificial galvanic corrosion portions 28, 29, 38, and 39 compared to the case in which a base material BM without embossed portions 60 is used. In other words, it was possible to manufacture separators 20 and 30 in which the sacrificial galvanic corrosion portions 28, 29, 38, and 39 have more exposed portions 280, 290, 380, and 39 than other parts. As a result, electrolytic corrosion progressed from each of the multiple exposed areas 280, 290, 380, and 390, causing the sacrificial electrolytic corrosion areas 28, 29, 38, and 39 to be widely dissolved throughout, and generating a corrosion-preventive current in the coolant inlet and outlet areas IA and OA. In this way, by prioritizing the electrolytic corrosion of the sacrificial electrolytic corrosion areas 28, 29, 38, and 39 over other parts, the cell internal seal areas 26a, 26b, 36a, and 36b could be protected.

[0031] Figure 7 shows the verification results of the formation intervals of exposed areas 280, 290, 380, and 390 in the sacrificial galvanic corrosion areas 28, 29, 38, and 39. In the verification related to Figure 7, a coating FL made of titanium and carbon was formed on stainless steel foil as the base material BM by vacuum deposition, and the exposed areas 280, 290, 380, and 390 in the sacrificial galvanic corrosion areas 28, 29, 38, and 39 were reproduced by stretching it at a specific elongation rate. Figure 7 shows the appearance of the sacrificial galvanic corrosion areas 28, 29, 38, and 39 as they were reproduced in this way. In each figure of Figure 7, the exposed areas 280, 290, 380, and 390 correspond to the striped black areas. The area N enclosed by the dotted line is the part of the sacrificial galvanic corrosion area 28, 29, 38, and 39 that does not have exposed areas 280, 290, 380, and 390.

[0032] As shown in the left panel of Figure 7, when the elongation rate was 10%, the spacing between exposed areas 280, 290, 380, and 390 in the sacrificial galvanized areas 28, 29, 38, and 39 was approximately 30 μm. As shown in the center panel of Figure 7, when the elongation rate was 20%, the spacing between exposed areas 280, 290, 380, and 390 in the sacrificial galvanized areas 28, 29, 38, and 39 was approximately 10 μm. As shown in the right panel of Figure 7, when the elongation rate was 30%, the spacing between exposed areas 280, 290, 380, and 390 in the sacrificial galvanized areas 28, 29, 38, and 39 was approximately 5 μm. A certain effect was obtained at all spacings, but a particularly significant effect was obtained when the sacrificial galvanized areas 28, 29, 38, and 39 had multiple exposed areas 280, 290, 380, and 390 at intervals of 10 μm or less.

[0033] According to the above embodiment, separators 20 and 30 can be manufactured using a base material BM whose surface is covered with a coating FL and which has an embossed portion 60 having a plurality of protrusions 601-616 between the coolant manifolds 42 and 45 and the cell seal portions 26a, 26b, 36a, and 36b. In this way, when forming the separators 20 and 30 by press working on the base material BM whose surface is covered with a coating FL, the plurality of protrusions 601-616 formed on the base material BM can be stretched by utilizing the external force applied by the press working. As a result, the coating FL on the protrusions 601-616 can be broken, and sacrificial galvanic corrosion portions 28, 29, 38, and 39 having a plurality of exposed portions 280, 290, 380, and 390 can be formed between the coolant manifolds 42 and 45 and the cell seal portions 26a, 26b, 36a, and 36b. In other words, the molding process includes an exposure process that forms exposed portions 280, 290, 380, 390 of the sacrificial galvanic corrosion portions 28, 29, 38, 393 at positions corresponding to the protrusions 601-616 of the embossed portion 60. In this way, more exposed portions 280, 290, 380, 390 can be formed on the sacrificial galvanic corrosion portions 28, 29, 38, 39 compared to the case where a substrate BM without the embossed portion 60 is used. In this way, because the sacrificial galvanic corrosion portions 28, 29, 38, 39 have more exposed portions 280, 290, 380, 390 than other parts, the sacrificial galvanic corrosion portions 28, 29, 38, 39 can be galvanized preferentially over other parts. This suppresses the occurrence of pinholes PH in the cell seal portions 26a, 26b, 36a, 36b. Therefore, a decrease in sealing performance can be suppressed.

[0034] Furthermore, according to the above embodiment, the embossed portion 60 has at least one projection 601-616 on the straight line L1-L16 connecting the coolant manifolds 42, 45 and the cell seal portions 26a, 26b, 36a, 36b. This makes it possible to form sacrificial galvanic corrosion portions 28, 29, 38, 39 having at least one exposed portion 280, 290, 380, 390 on the straight line L1-L16 connecting the coolant manifolds 42, 45 and the cell seal portions 26a, 26b, 36a, 36b. In this way, the coolant passes over the exposed portion 280, 290, 380, 390 at least once between the coolant manifolds 42, 45 and the coolant flow path 49. This makes it possible to more reliably and preferentially galvanize the sacrificial galvanic corrosion portions 28, 29, 38, 39 than other parts. Therefore, the occurrence of pinhole PH in the cell seal portions 26a, 26b, 36a, and 36b can be suppressed more reliably, thereby further suppressing a decrease in sealing performance.

[0035] Furthermore, according to the above embodiment, the embossed portion 60 has projections 601-616 on two or more concentric circles C1, C2 centered on the coolant manifolds 42, 45. This makes it possible to form sacrificial galvanic corrosion portions 28, 29, 38, 39 having exposed portions 280, 290, 380, 390 on two or more concentric circles C1, C2 centered on the coolant manifolds 42, 45. In this way, the probability that the coolant passes over the exposed portions 280, 290, 380, 390 between the coolant manifolds 42, 45 and the coolant flow path 49 can be increased. This makes it possible to more reliably prioritize galvanic corrosion on the sacrificial galvanic corrosion portions 28, 29, 38, 39 over other parts. Therefore, it is possible to more reliably suppress the occurrence of pinhole PH in the cell seal portions 26a, 26b, 36a, 36b, thereby further suppressing a decrease in sealing performance.

[0036] Furthermore, according to the above embodiment, the embossed portion 60 has a plurality of protrusions 601-616 spaced at intervals of 10 μm or less. This makes it possible to form sacrificial galvanic corrosion portions 28, 29, 38, 39 having a plurality of exposed portions 280, 290, 380, 390 spaced at intervals of 10 μm or less. In this way, the probability that the coolant passes over the exposed portions 280, 290, 380, 390 between the coolant manifolds 42, 45 and the coolant flow path 49 can be increased. This makes it possible to more reliably prioritize galvanic corrosion on the sacrificial galvanic corrosion portions 28, 29, 38, 39 over other parts. Therefore, the occurrence of pinhole PH in the cell seal portions 26a, 26b, 36a, 36b can be more reliably suppressed, and this makes it possible to further suppress the deterioration of sealing performance.

[0037] Furthermore, according to the above embodiment, a coolant flow path 49 is formed between the cooling surface 20c of the anode separator 20 and the cooling surface 30c of the cathode separator 30 of adjacent fuel cell cells 100. Of the coolant flow path 49, the coolant inlet / outlet regions IA and OA, located between the coolant manifolds 42 and 45 and the cell internal seal portions 26a, 26b, 36a, and 36b, have a larger coolant flow rate per unit area of ​​the fuel cell cell 100 compared to other regions. Therefore, the contribution of pressure loss when the coolant flows is larger in the coolant inlet / outlet regions IA and OA compared to other regions. Accordingly, in order to reduce pressure loss in the coolant inlet / outlet regions IA and OA, it is desirable that the protrusions 601-616 of the embossed portion 60 protrude in a direction that can increase the space between the anode separator 20 and cathode separator 30 of adjacent fuel cell cells 100. According to the above embodiment, as shown in the left diagram of Figure 6, in both the anode separator 20 and the cathode separator 30, the protrusions 601-616 protrude from the gas surfaces 20g and 30g, which are the opposing surfaces of the main body portions 21 and 31 facing the insulating sheet 12, to the cooling surfaces 20c and 30c, which are the opposite surfaces of the opposing surfaces. In this way, the space between the anode separator 20 and the cathode separator 30 of adjacent fuel cell cells 100 can be increased compared to the configurations shown in the center and right diagrams of Figure 6. In other words, the space between the separators 20 and 30 and the insulating sheet 12 can be reduced. This reduces the pressure loss in the coolant inlet and outlet regions IA and OA.

[0038] Furthermore, according to the above embodiment, as shown in Figure 4, the shape of the protrusions 601-616 is elliptical. This increases the likelihood that the protrusions 601-616 will overlap with the anode separator 20 and cathode separator 30 of adjacent fuel cell cells 100, even if the stacking positions of the fuel cell cells 100 are misaligned when the fuel cell cells 100 are stacked. This suppresses the floating of the fuel cell cells 100 in the coolant inlet / outlet regions IA and OA. Note that the shape of the protrusions 601-616 may also be circular.

[0039] 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 of 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]

[0040] 1…Fuel cell stack, 10…Plate member, 11…Membrane electrode gas diffusion layer assembly, 11r…Outer periphery, 12…Insulating sheet, 13…Opening, 20,20v…Anode separator, 20c,30c…Cooling surface, 20g,30g…Gas surface, 21,31…Main body, 22,32…Protruding part, 24,25,34,35…Rib part, 26a-26e,36a,36e…In-cell seal part, 28,29,38,39…Sacrificial corrosion part, 30,30v…Cathode separator, 41,46…Oxidizer gas introduction manifold, 42,45…Coolant manifold, 43,44…Fuel gas manifold, 47…Fuel gas flow path, 48…Oxidizer gas flow path, 49…Coolant flow path, 51…First gasket, 52…Second gasket, 53…Third Gasket, 54…4th gasket, 55…5th gasket, 60…embossed part, 100…fuel cell, 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, 280, 290, 380, 390…exposed part, 601-616…protrusion, 650…connection part, BM…substrate, C1, C2…concentric circles, DL…lamination direction, EN…endpoint, FL…coating, IA…coolant introduction area, L1-L16…straight line, N…part without exposed area, OA…coolant outlet area, PH…pinhole, PM1-PM16…points on the coolant manifold, PS1-PS16…points on the seal part inside the cell, SP…seal position, ST…starting point

Claims

1. It is a fuel cell cell, A plate member having a membrane electrode gas diffusion layer assembly and an insulating sheet that holds the outer periphery of the membrane electrode gas diffusion layer assembly, an anode separator and a cathode separator for sandwiching the plate member, comprising an anode separator and a cathode separator having a coating on their surface, The anode separator and the cathode separator are, respectively, The main body and A coolant manifold as an opening formed in the main body, comprising a coolant manifold through which coolant flows, The main body is bonded to the insulating sheet so as to surround the coolant manifold, thereby forming an internal cell sealing portion that seals the space between the anode separator and the cathode separator within the fuel cell. A sacrificial galvanic corrosion section is disposed between the coolant manifold and the cell internal seal section, and comprises a plurality of exposed portions in which the substrate is exposed without being covered by the coating, The fuel cell has a sacrificial corrosion portion having at least one exposed portion on a straight line connecting the coolant manifold and the cell internal seal portion.

2. A fuel cell cell according to claim 1, The sacrificial corrosion portion is a fuel cell cell having the exposed portion on two or more concentric circles centered on the coolant manifold.

3. A fuel cell cell according to claim 1, The sacrificial corrosion portion is a fuel cell having a plurality of exposed portions spaced at intervals of 10 μm or less.

4. A method for manufacturing a fuel cell cell, A plate preparation step involves preparing a plate member having (1a) a membrane electrode gas diffusion layer assembly and (1b) an insulating sheet that holds the outer periphery of the membrane electrode gas diffusion layer assembly, A substrate preparation step for preparing a substrate for an anode separator and a cathode separator, the substrate having (2a) a main body, (2b) a coolant manifold as an opening formed in the main body for circulating coolant, and (2c) an embossed portion disposed near the coolant manifold, the embossed portion having a plurality of protrusions projecting from the main body. A surface treatment step of treating the surface of the substrate to form a film on the surface of the substrate, A molding step in which the anode separator and the cathode separator are molded into a predetermined shape by pressing the substrate on which the coating has been formed, The process includes forming an internal cell seal portion by bonding the insulating sheet to the main body so as to surround the coolant manifold while the plate member is sandwiched between the anode separator and the cathode separator, thereby forming an internal cell seal portion that seals the space between the anode separator and the cathode separator within the fuel cell, A method for manufacturing a fuel cell, wherein the molding step includes an exposure step which involves using the external force applied by the pressing process to stretch the protrusions and break the coating on the protrusions, thereby forming sacrificial corrosion portions having a plurality of exposed portions in which the substrate is exposed without being covered by the coating.

5. A method for manufacturing a fuel cell according to claim 4, A method for manufacturing a fuel cell, wherein the projection protrudes from the side of the main body facing the insulating sheet to the side opposite the opposing surface.

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