Fuel cell systems and maintenance methods for fuel cell systems

Abstract

This invention provides a fuel cell system and a maintenance method for the fuel cell system that are suitable for improving the durability of electrolyte membranes containing metal ions. [Solution] The fuel cell system 300 of the present disclosure includes a plurality of fuel cell cells 100 and at least one fuel cell stack 200 having fuel gas holes 41, oxidizer gas holes 51, and refrigerant holes 61 formed therein, which extend in the thickness direction of the fuel cell cells 100 and penetrate the plurality of fuel cell cells 100, and a structure or element that reverses at least one selected from the group consisting of the flow direction of fuel gas Ga inside the fuel gas holes 41, the flow direction of oxidizer gas Gc inside the oxidizer gas holes 51, and the flow direction of refrigerant Mc inside the refrigerant holes 61. The fuel cell cell 100 includes an anode 13, a cathode 16, and a membrane electrode assembly 10 including an electrolyte membrane 12 containing metal ions.

Description

Technical Field

[0001] The present disclosure relates to a fuel cell system and a method for maintaining the fuel cell system.

Background Art

[0002] Patent Document 1 discloses a technique for improving the durability of a solid polymer electrolyte fuel cell by containing ions of at least one metal among Ce, Tl, Mn, Ag, and Yb in a solid polymer electrolyte membrane.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When a fuel cell is operated, heat and water generated by the reaction cause a bias in the distribution of the water content inside the fuel cell stack, and water moves from a region with a large water content to a region with a small water content. The metal ions contained in the solid polymer electrolyte membrane have the property of moving along with this movement of water. Therefore, when the fuel cell is operated for a long time, there is a problem that a bias occurs in the metal ion concentration in the solid polymer electrolyte membrane, and deterioration of the solid polymer electrolyte membrane is likely to occur in the portion where the concentration has decreased.

Means for Solving the Problems

[0005] The fuel cell system in the present disclosure includes a plurality of fuel cells, and at least one fuel cell stack in which fuel gas holes, oxidant gas holes, and refrigerant holes that extend in the thickness direction of the fuel cells and penetrate the plurality of fuel cells are formed, A structure or element that reverses at least one selected from the group consisting of the fuel gas flow direction inside the fuel gas hole, the oxidizer gas flow direction inside the oxidizer gas hole, and the refrigerant flow direction inside the refrigerant hole, Equipped with, The fuel cell comprises a membrane electrode assembly including an anode, a cathode, and an electrolyte membrane containing metal ions.

[0006] In another respect, the maintenance method for the fuel cell system in this disclosure is A maintenance method for a fuel cell system comprising a fuel cell stack including a plurality of fuel cell cells, and having at least one fuel cell stack having fuel gas holes, oxidizer gas holes, and refrigerant holes that extend in the thickness direction of the fuel cell cells and penetrate the plurality of fuel cell cells, The fuel cell comprises a membrane electrode assembly including an anode, a cathode, and an electrolyte membrane containing metal ions. After performing an operation in which fuel gas is circulated through the fuel gas holes, oxidizer gas is circulated through the oxidizer gas holes, and refrigerant is circulated through the refrigerant holes, the operation includes reversing at least one selected from the group consisting of the flow direction of fuel gas inside the fuel gas holes, the flow direction of oxidizer gas inside the oxidizer gas holes, and the flow direction of refrigerant inside the refrigerant holes. [Effects of the Invention]

[0007] According to this disclosure, the durability of an electrolyte membrane containing metal ions can be improved. [Brief explanation of the drawing]

[0008] [Figure 1] Block diagram showing the configuration of the fuel cell system in Embodiment 1 [Figure 2] Partial schematic cross-sectional view of the fuel cell system in Embodiment 1 [Figure 3A] Schematic cross-sectional view illustrating the first operating mode of the fuel cell system in Embodiment 1. [Figure 3B]Schematic cross-sectional view for explaining the second operation mode of the fuel cell system in Embodiment 1 [Figure 4] First plan view of the anode separator [Figure 5] Plan view of the cathode separator [Figure 6] Second plan view of the anode separator [Figure 7A] Schematic cross-sectional view for explaining the first operation mode of the fuel cell system in the modified example [Figure 7B] Schematic cross-sectional view for explaining the transition state from the first operation mode to the second operation mode of the fuel cell system in the modified example [Figure 7C] Schematic cross-sectional view for explaining the second operation mode of the fuel cell system in the modified example [Figure 8] Plan view (A) along the thickness direction before inverting the fuel cell stack, plan view (B) along the thickness direction after inverting the fuel cell stack, and plan view (C) obtained by overlapping (A) and (B) [Figure 9] Block diagram showing the configuration of the fuel cell system in Embodiment 2 [Figure 10] Schematic cross-sectional view for explaining the first operation mode of the fuel cell system in Embodiment 2 [Figure 11] Schematic cross-sectional view for explaining the second operation mode of the fuel cell system in Embodiment 2

Embodiments for Carrying Out the Invention

[0009] (Findings etc. on which the present disclosure is based) When a fuel cell is operated, hydrogen peroxide is generated as a side reaction product due to an electrochemical reaction. When impurities such as iron ions and copper ions are present in an electrolyte membrane or the like included in the fuel cell, the side reaction product hydrogen peroxide is decomposed by these impurities, and radicals such as hydroxyl radicals and hydroperoxy radicals are generated. It is known that these radicals decompose and deteriorate the electrolyte membrane. When the inventors of the present disclosure came up with the present disclosure, it was considered that deterioration of the electrolyte membrane was suppressed by inactivating radicals by containing metal ions in the electrolyte membrane (for example, Patent Document 1).

[0010] Also, when the inventors of the present disclosure came up with the present disclosure, it was considered that increasing the water content rate of the electrolyte membrane led to suppression of deterioration of the electrolyte membrane. Therefore, a refrigerant inlet is provided near an oxidant gas inlet and a fuel gas inlet, a refrigerant flow path is arranged along the oxidant gas flow path and the fuel gas flow path, and the temperature of the refrigerant is set so as to keep the relative humidity of the oxidant gas on the oxidant gas inlet side and the relative humidity of the fuel gas on the fuel gas inlet side high, thereby controlling the water content rate of the electrolyte membrane. However, it is difficult to control the water content rate of the electrolyte membrane only with such a configuration. This is because the temperatures of the oxidant gas and the fuel gas rise from the upstream side to the downstream side of the oxidant gas flow path and the fuel gas flow path flowing along the refrigerant flow path due to the heat generated by the heat generation reaction during power generation. As a result, in the electrolyte membrane and the catalyst layer located on the downstream side of the oxidant gas flow path, the fuel gas flow path, and the refrigerant flow path, the relative humidity decreases due to an increase in the amount of saturated water vapor in the gas flow path, and the water content rate of the electrolyte membrane tends to be lower than an appropriate level.

[0011] Under such circumstances, the inventors of the present disclosure discovered a new problem that a bias may also occur in the metal ion concentration in the plane direction of the electrolyte membrane along with the bias in the amount of water in the plane direction of the electrolyte membrane. This is presumably because metal ions move along with the movement of water in the plane direction of the electrolyte membrane. In a portion of the electrolyte membrane where the metal ion concentration is relatively low, the ability to avoid attack by radicals is low, so deterioration tends to progress.

[0012] Therefore, the present inventors focused on improving the uneven distribution of metal ion content in the planar direction of the electrolyte membrane, which constitutes the subject of this disclosure.

[0013] This disclosure provides a fuel cell system suitable for improving the durability of an electrolyte membrane containing metal ions, and a method for maintaining the fuel cell system.

[0014] The embodiments will be described in detail below with reference to the drawings. However, unnecessary details may be omitted. For example, detailed explanations of already well-known matters or redundant explanations of substantially identical configurations may be omitted. This is to avoid the following explanation becoming unnecessarily verbose and to facilitate understanding for those skilled in the art.

[0015] The attached drawings and the following description are provided to enable the parties to fully understand this disclosure and are not intended to limit the subject matter described in the claims.

[0016] (Embodiment 1) Embodiment 1 will be described below with reference to Figures 1 to 8.

[0017] [1-1. Structure] Figure 1 is a block diagram showing the configuration of the fuel cell system 300 in Embodiment 1. Figure 2 is a partial schematic cross-sectional view of the fuel cell system 300 in Embodiment 1. The fuel cell system 300 comprises a fuel cell stack 200. As shown in Figure 2, the fuel cell stack 200 includes a plurality of fuel cell cells 100. The plurality of fuel cell cells 100 are stacked along the thickness direction of the fuel cell 100. The fuel cell stack 200 has fuel gas holes 41, oxidizer gas holes 51, and refrigerant holes 61 that penetrate the plurality of fuel cell cells 100. In the example of Figure 1, the ±X direction is the thickness direction of the fuel cell 100. The ±Y direction and ±Z direction are directions perpendicular to the thickness direction of the fuel cell 100, respectively. The ±Y direction and ±Z direction correspond to the surface direction of the fuel cell 100. In this specification, "surface direction of the fuel cell 100" means, for example, the direction in which the main surface of the fuel cell 100 extends.

[0018] The fuel gas holes 41, oxidizer gas holes 51, and refrigerant holes 61 are holes that extend in the thickness direction of the fuel cell 100 and penetrate the fuel cell 100. In the example shown in Figure 2, the fuel gas holes 41, oxidizer gas holes 51, and refrigerant holes 61 each extend in the thickness direction of multiple fuel cell cells 100 and penetrate multiple fuel cell cells 100. The fuel gas holes 41 allow the flow of fuel gas Ga. The oxidizer gas holes 51 allow the flow of oxidizer gas Gc. The refrigerant holes 61 allow the flow of refrigerant Mc. In the example shown in Figure 2, for convenience, the positions of the fuel gas holes 41, oxidizer gas holes 51, and refrigerant holes 61 are shown offset in the ±Z direction. However, in a cross-section parallel to the thickness direction of the fuel cell system 300, the fuel gas holes 41, oxidizer gas holes 51, and refrigerant holes 61 may be positioned to overlap in the ±Z direction.

[0019] The fuel cell cell 100 comprises a membrane electrode assembly 10, an anode separator 20, and a cathode separator 30. The membrane electrode assembly 10 is positioned between the anode separator 20 and the cathode separator 30. The fuel cell stack 200 is, for example, a polymer electrolyte fuel cell (PEFC).

[0020] The membrane electrode assembly 10 can also be used in other electrochemical devices, such as hydrogen generation devices that produce hydrogen.

[0021] The membrane electrode assembly 10 comprises an anode 13, an electrolyte membrane 12, and a cathode 16. The anode 13 is bonded to one side of the electrolyte membrane 12. The cathode 16 is bonded to the other side of the electrolyte membrane 12.

[0022] The membrane electrode assembly 10 may include a frame 19. The frame 19 is positioned around the membrane electrode assembly 10 and fixes the membrane electrode assembly 10 between the anode separator 20 and the cathode separator 30. The frame 19 maintains airtightness around the membrane electrode assembly 10. The frame 19 may be made of a metal component, a resin component, or a combination of these components.

[0023] The electrolyte membrane 12 is positioned between the anode 13 and the cathode 16. The electrolyte membrane 12 is made of a proton-conducting polymer material and contains metal ions. Examples of polymer materials include perfluorocarbon sulfonic acid-based polymer materials having sulfonic acid groups and hydrocarbon-based polymer materials. Examples of metal ions include Ce, Tl, Mn, Ag, and Yb. The electrolyte membrane 12 contains at least one of these metal ions.

[0024] The fuel cell system 300 in Embodiment 1 has a structure or element that reverses at least one selected from the group consisting of the flow direction of fuel gas Ga inside the fuel gas port 41, the flow direction of oxidant gas Gc inside the oxidant gas port 51, and the flow direction of refrigerant Mc inside the refrigerant port 61.

[0025] In this specification, the flow direction of fuel gas Ga inside the fuel gas port 41, the flow direction of oxidant gas Gc inside the oxidant gas port 51, and the flow direction of refrigerant Mc inside the refrigerant port 61 refer specifically to the flow direction of fuel gas Ga along the thickness direction, the flow direction of oxidant gas Gc along the thickness direction, and the flow direction of refrigerant Mc along the thickness direction when the fuel cell cell 100 is viewed in plan in the thickness direction. "Reversing the flow direction of fuel gas Ga inside the fuel gas port 41" can be rephrased as "switching the flow direction of fuel gas Ga inside the fuel cell cell 100 to the opposite direction." "Reversing the flow direction of oxidant gas Gc inside the oxidant gas port 51" can be rephrased as "switching the flow direction of oxidant gas Gc inside the fuel cell cell 100 to the opposite direction." "Reversing the flow direction of refrigerant Mc inside the refrigerant port 61" can be rephrased as "switching the flow direction of refrigerant Mc inside the fuel cell cell 100 to the opposite direction."

[0026] As described above, the electrolyte membrane 12 contains metal ions. Therefore, when the fuel cell system 300 is operated for a certain period of time, a bias in the water content occurs in the planar direction of the electrolyte membrane 12, particularly in the ±Z direction. Consequently, a bias may also occur in the metal ion content of the electrolyte membrane 12 in the ±Z direction.

[0027] According to the fuel cell system 300 in Embodiment 1, even if there is a bias in the metal ion content of the electrolyte membrane 12 in the ±Z direction, at least one selected from the group consisting of the flow direction of fuel gas Ga inside the fuel gas holes 41, the flow direction of oxidant gas Gc inside the oxidant gas holes 51, and the flow direction of refrigerant Mc inside the refrigerant holes 61 can be reversed. By reversing the bias in the water content of the electrolyte membrane 12 in the ±Z direction, the direction of movement of metal ions in the electrolyte membrane 12 can be reversed, and the metal ion content in the ±Z direction can be made uniform. As a result, the ability to avoid attack by radicals can be maintained, and the durability of the electrolyte membrane 12 can be improved. According to the fuel cell system 300 in Embodiment 1, the lifespan of the fuel cell system 300 can be extended.

[0028] The above structure or element may include a pump capable of reversing the flow direction. The fuel cell system 300 may reverse at least one selected from the group consisting of the flow direction of fuel gas Ga inside the fuel gas port 41, the flow direction of oxidant gas Gc inside the oxidant gas port 51, and the flow direction of refrigerant Mc inside the refrigerant port 61 by a pump capable of reversing the flow direction.

[0029] In the example shown in Figure 2, the fuel gas holes 41 are configured to allow fuel gas Ga to flow from the first side 200a to the second side 200b of the fuel cell stack 200. For each fuel cell cell 100, the fuel gas holes 41 are configured to allow fuel gas Ga to flow from the first side 10a to the second side 10b of the membrane electrode assembly 10. The oxidizer gas holes 51 are configured to allow oxidizer gas Gc to flow from the second side 200b to the first side 200a of the fuel cell stack 200. For each fuel cell cell 100, the oxidizer gas holes 51 are configured to allow oxidizer gas Gc to flow from the second side 10b to the first side 10a of the membrane electrode assembly 10. The refrigerant holes 61 are configured to allow refrigerant Mc to flow from the second side 200b to the first side 200a of the fuel cell stack 200. In each fuel cell cell 100, the refrigerant holes 61 are configured so that the refrigerant Mc flows from the second side 10b to the first side 10a of the membrane electrode assembly 10. In other words, the flow of fuel gas Ga inside the fuel gas holes 41 is opposed to the flow of oxidizer gas Gc inside the oxidizer gas holes 51 and the flow of refrigerant Mc inside the refrigerant holes 61.

[0030] The anode 13 comprises an anode catalyst layer 14 and an anode gas diffusion layer 15. The anode catalyst layer 14 is positioned between the electrolyte membrane 12 and the anode gas diffusion layer 15. The cathode 16 comprises a cathode catalyst layer 17 and a cathode gas diffusion layer 18. The cathode catalyst layer 17 is positioned between the electrolyte membrane 12 and the cathode gas diffusion layer 18.

[0031] The anode catalyst layer 14 has the function of promoting an electrochemical reaction that dissociates hydrogen molecules into protons. The anode catalyst layer 14 comprises an electrode catalyst and a polymer electrolyte. The anode catalyst layer 14 may also comprise carbon particles supporting catalyst particles and a polymer electrolyte as the electrode catalyst.

[0032] The anode gas diffusion layer 15 has the function of supplying fuel gas Ga (anode gas) to the anode catalyst layer 14 and receiving electrons from the anode catalyst layer 14. The anode gas diffusion layer 15 is composed of a material that is gas permeable and conductive. The anode gas diffusion layer 15 has, for example, a conductive porous body as its main material. Examples of porous bodies include carbon fiber aggregates such as carbon paper.

[0033] The cathode catalyst layer 17 has the function of promoting an electrochemical reaction that produces water from protons and oxygen. The cathode catalyst layer 17 comprises an electrode catalyst and a polymer electrolyte. The cathode catalyst layer 17 may also comprise carbon particles supporting catalyst particles and a polymer electrolyte as the electrode catalyst. The cathode catalyst layer 17 may further comprise conductive fibers.

[0034] The cathode gas diffusion layer 18 has the function of supplying oxidizing gas Gc (cathode gas) to the cathode catalyst layer 17 and the function of transferring electrons to the cathode catalyst layer 17. The cathode gas diffusion layer 18 is composed of a material that is gas permeable and conductive. The cathode gas diffusion layer 18 mainly includes, for example, a conductive porous body. Examples of porous bodies include carbon fiber aggregates such as carbon paper.

[0035] An example of fuel gas Ga is hydrogen-containing gas. Hydrogen-containing gas may be gas produced from hydrocarbons by steam reforming, or it may be pure hydrogen gas with a hydrogen gas concentration of 99% or higher. An example of oxidizing gas Gc is air.

[0036] A fuel gas passage 40 is provided in the planar direction between the anode 13 and the anode separator 20. The fuel gas passage 40 communicates with the fuel gas hole 41. Fuel gas Ga is supplied to the anode 13 through the fuel gas passage 40. In this embodiment, a groove serving as the fuel gas passage 40 is provided in the anode separator 20. However, the fuel gas passage 40 may be formed by a component other than the anode separator 20.

[0037] An oxidizing agent gas channel 50 is provided in the planar direction between the cathode 16 and the cathode separator 30. The oxidizing agent gas channel 50 is in communication with the oxidizing agent gas hole 51. Oxidizing agent gas Gc is supplied to the cathode 16 through the oxidizing agent gas channel 50. In this embodiment, a groove serving as the oxidizing agent gas channel 50 is provided in the cathode separator 30. However, the oxidizing agent gas channel 50 may be formed by a component other than the cathode separator 30.

[0038] The anode separator 20 and the cathode separator 30 are made of conductive materials such as carbon and metal, respectively. To prevent corrosion, they may be coated with a corrosion-resistant film such as resin or plating.

[0039] The fuel cell cell 100 further includes a refrigerant channel 60, which is separated from the oxidant gas channel 50 by a cathode separator 30. The refrigerant channel 60 communicates with a refrigerant hole 61. A refrigerant Mc, such as brine or water, is supplied to the membrane electrode assembly 10 through the refrigerant channel 60. In this embodiment, a groove serving as the refrigerant channel 60 is provided in the anode separator 20. That is, a fuel gas channel 40 is provided on the first surface of the anode separator 20, and a refrigerant channel 60 is provided on the second surface of the anode separator 20. The first and second surfaces of the anode separator 20 refer to the two main surfaces of the plate-shaped anode separator 20. The surface in contact with the anode 13 is the first surface, and the surface in contact with the cathode separator 30 is the second surface.

[0040] The refrigerant flow path 60 may be formed by a component separate from the anode separator 20. The refrigerant flow path 60 may be located between the anode separator 20 and the cathode separator 30 in adjacent fuel cell cells 100.

[0041] In the example shown in Figure 2, a first fuel gas opening 41a is located at the first end of the fuel gas port 41, and a second fuel gas opening 41b is located at the second end of the fuel gas port 41. A first oxidizer gas opening 51a is located at the second end of the oxidizer gas port 51, and a second oxidizer gas opening 51b is located at the first end of the oxidizer gas port 51. A first refrigerant opening 61a is located at the second end of the refrigerant port 61, and a second refrigerant opening 61b is located at the first end of the refrigerant port 61.

[0042] The above structure or element may include a structure that reverses at least one selected from the group consisting of the flow direction of fuel gas Ga at the first opening 41a for fuel gas, the flow direction of oxidant gas Gc at the first opening 51a for oxidant gas, and the flow direction of refrigerant Mc at the first opening 61a for refrigerant. By reversing the bias in the moisture content of the electrolyte membrane 12 in the ±Z direction, the direction of movement of metal ions in the electrolyte membrane 12 can be reversed, and the metal ion content in the ±Z direction can be made uniform.

[0043] The fuel cell system 300 further includes a fuel gas supply path 42 connected to a first fuel gas opening 41a, a fuel gas discharge path 43 connected to a second fuel gas opening 41b, an oxidizer gas supply path 52 connected to a first oxidizer gas opening 51a, an oxidizer gas discharge path 53 connected to a second oxidizer gas opening 51b, a refrigerant supply path 62 connected to a first refrigerant opening 61a, and a refrigerant discharge path 63 connected to a second refrigerant opening 61b.

[0044] In the example shown in Figure 2, the fuel gas port 41 has a first portion 411 extending from the first fuel gas opening 41a and a second portion 412 extending toward the second fuel gas opening 41b. The first portion 411 is in communication with the fuel gas flow path 40, and the fuel gas flow path 40 is in communication with the second portion 412. For example, fuel gas Ga supplied from the first fuel gas opening 41a flows through the first portion 411, which is provided in the thickness direction, and then flows into the fuel gas flow path 40, which is provided in the plane direction. This supplies fuel gas Ga to the anode 13. For example, unused fuel gas Ga that flows out of the fuel gas flow path 40 flows through the second portion 412, which is provided in the thickness direction, and then is discharged from the second fuel gas opening 41b. In this way, fuel gas Ga can be supplied to the fuel gas flow path 40 from outside the fuel cell stack 200, and unused fuel gas Ga can be discharged from the fuel gas flow path 40 to the outside of the fuel cell stack 200.

[0045] In the example shown in Figure 2, the oxidizing gas pore 51 has a first portion 511 extending from the first opening 51a for the oxidizing gas and a second portion 512 extending toward the second opening 51b for the oxidizing gas. The first portion 511 is in communication with the oxidizing gas flow path 50, and the oxidizing gas flow path 50 is in communication with the second portion 512. For example, the oxidizing gas Gc supplied from the first opening 51a for the oxidizing gas flows through the first portion 511, which is provided in the thickness direction, and then flows into the oxidizing gas flow path 50, which is provided in the plane direction. This supplies the oxidizing gas Gc to the cathode 16. For example, any unused oxidizing gas Gc that flows out of the oxidizing gas flow path 50 flows through the second portion 512, which is provided in the thickness direction, and then is discharged from the second opening 51b for the oxidizing gas. In this way, oxidant gas Gc can be supplied to the oxidant gas flow path 50 from outside the fuel cell stack 200, and unused oxidant gas Gc and water vapor can be discharged from the oxidant gas flow path 50 to the outside of the fuel cell stack 200.

[0046] In the example shown in Figure 2, the refrigerant hole 61 has a first portion 611 extending from the first refrigerant opening 61a and a second portion 612 extending toward the second refrigerant opening 61b. The first portion 611 communicates with the refrigerant flow path 60, and the refrigerant flow path 60 communicates with the second portion 612. For example, refrigerant Mc supplied from the first refrigerant opening 61a flows through the first portion 611, which is provided in the thickness direction, and then flows into the refrigerant flow path 60, which is provided in the surface direction. This supplies refrigerant Mc to the membrane electrode assembly 10. For example, refrigerant Mc that flows out from the refrigerant flow path 60 flows through the second portion 612, which is provided in the thickness direction, and then is discharged from the second refrigerant opening 61b. In this way, refrigerant Mc can be supplied to the refrigerant flow path 60 from outside the fuel cell stack 200, and refrigerant Mc can be discharged from the refrigerant flow path 60 to the outside of the fuel cell stack 200.

[0047] In Embodiment 1, the above structure or element may include at least one selected from the group consisting of the following structures A, B, and C. (Structure A) A structure that allows a fuel gas discharge path 43 to be connected to a first fuel gas opening 41a and a fuel gas supply path 42 to a second fuel gas opening 41b. (Structure B) A structure that allows an oxidant gas discharge path 53 to be connected to the first opening 51a for oxidant gas, and an oxidant gas supply path 52 to be connected to the second opening 51b for oxidant gas. (Structure C) A structure that allows a refrigerant discharge path 63 to be connected to the first refrigerant opening 61a and a refrigerant supply path 62 to be connected to the second refrigerant opening 61b.

[0048] In this case, without changing the configuration of the fuel cell system 300, at least one selected from the group consisting of the flow direction of fuel gas Ga inside the fuel gas port 41, the flow direction of oxidant gas Gc inside the oxidant gas port 51, and the flow direction of refrigerant Mc inside the refrigerant port 61 can be reversed. Therefore, the cost required to obtain the above-mentioned effects can be reduced.

[0049] Structure A includes, for example, Structure A-1 in which the fuel gas supply path 42 and the fuel gas discharge path 43 are made of flexible pipes, and the first fuel gas opening 41a and the second fuel gas opening 41b are within reach of the flexible fuel gas supply path 42, and the first fuel gas opening 41a and the second fuel gas opening 41b are within reach of the flexible fuel gas discharge path 43; and Structure A-2 in which the opening diameter of the first fuel gas opening 41a and the opening diameter of the second fuel gas opening 41b are the same so that the fuel gas supply path 42 and the fuel gas discharge path 43 can be connected to either the first fuel gas opening 41a or the second fuel gas opening 41b, respectively.

[0050] Structure B includes, for example, Structure B-1 in which the oxidizing gas supply path 52 and the oxidizing gas discharge path 53 are made of flexible pipes, and the first opening 51a and the second opening 51b for oxidizing gas are within the reach of the flexible oxidizing gas supply path 52, and the first opening 51a and the second opening 51b for oxidizing gas are within the reach of the flexible oxidizing gas discharge path 53; and Structure B-2 in which the opening diameter of the first opening 51a and the opening diameter of the second opening 51b for oxidizing gas are the same so that the oxidizing gas supply path 52 and the oxidizing gas discharge path 53 can be connected to either the first opening 51a or the second opening 51b for oxidizing gas.

[0051] Structure C includes, for example, structure C-1 in which the refrigerant supply path 62 and the refrigerant discharge path 63 are made of flexible pipes, and the first refrigerant opening 61a and the second refrigerant opening 61b are within the reach of the flexible refrigerant supply path 62, and the first refrigerant opening 61a and the second refrigerant opening 61b are within the reach of the flexible refrigerant discharge path 63; and structure B-2 in which the opening diameter of the first refrigerant opening 61a and the opening diameter of the second refrigerant opening 61b are the same so that the refrigerant supply path 62 and the refrigerant discharge path 63 can be connected to either the first refrigerant opening 61a or the second refrigerant opening 61b, respectively.

[0052] Figure 3A is a schematic cross-sectional view illustrating the first operating mode of the fuel cell system 300 shown in Figure 2. Figure 3B is a schematic cross-sectional view illustrating the second operating mode of the fuel cell system 300 shown in Figure 2. In Figures 3A and 3B, some elements are omitted for convenience so that the overall flow direction of the fuel gas Ga, the oxidizer gas Gc, and the refrigerant Mc during operation of the fuel cell system 300 can be clearly understood.

[0053] As shown in Figure 3A, when the first operating mode is running, the flow direction of the fuel gas Ga inside the fuel gas holes 41, specifically the first section 411 and the second section 412, is from the first side 200a to the second side 200b. The flow direction of the oxidizer gas Gc inside the oxidizer gas holes 51, specifically the first section 511 and the second section 512, is from the second side 200b to the first side 200a. The flow direction of the refrigerant Mc inside the refrigerant holes 61, specifically the first section 611 and the second section 612, is from the second side 200b to the first side 200a.

[0054] If the above structure or element includes at least one selected from the group consisting of structure A, structure B, and structure C, then at least one selected from the group consisting of the flow direction of fuel gas Ga inside the fuel gas hole 41, the flow direction of oxidant gas Gc inside the oxidant gas hole 51, and the flow direction of refrigerant Mc inside the refrigerant hole 61 can be reversed.

[0055] If structure A is included, as shown in Figure 3B, a fuel gas discharge path 43 can be connected to the first fuel gas opening 41a and a fuel gas supply path 42 can be connected to the second fuel gas opening 41b. If structure B is included, as shown in Figure 3B, an oxidizer gas discharge path 53 can be connected to the first oxidizer gas opening 51a and an oxidizer gas supply path 52 can be connected to the second oxidizer gas opening 51b. If structure C is included, as shown in Figure 3B, a refrigerant discharge path 63 can be connected to the first refrigerant opening 61a and a refrigerant supply path 62 can be connected to the second refrigerant opening 61b. As a result, as shown in Figure 3B, when the second operating mode is executed, the flow direction of the fuel gas Ga inside the fuel gas holes 41, specifically the second section 412 and the first section 411, can be switched from the second side 200b to the first side 200a. The flow direction of the oxidizing gas Gc inside the oxidizing gas holes 51, specifically the second section 512 and the first section 511, can be switched from the direction toward the first side 200a to the direction toward the second side 200b. The flow direction of the refrigerant Mc inside the refrigerant holes 61, specifically the second section 612 and the first section 611, can be switched from the direction toward the first side 200a to the direction toward the second side 200b. Therefore, even if the metal ion content in the ±Z direction of the electrolyte membrane 12 becomes uneven by running the first mode for a certain period of time, the metal ion content in the ±Z direction of the electrolyte membrane 12 can be made uniform by running the second operating mode.

[0056] As shown in Figure 2, the fuel cell system 300 may further include a first joint 45 provided at a first opening 41a for fuel gas and a second joint 46 provided at a second opening 41b for fuel gas. The fuel cell system 300 may further include a third joint 55 provided at a first opening 51a for oxidizer gas and a fourth joint 56 provided at a second opening 51b for oxidizer gas. The fuel cell system 300 may further include a fifth joint 65 provided at a first opening 61a for refrigerant and a sixth joint 66 provided at a second opening 61b for refrigerant.

[0057] The first joint 45 may be capable of connecting the first fuel gas opening 41a to the fuel gas supply path 42, and also capable of connecting the first fuel gas opening 41a to the fuel gas discharge path 43. The second joint 46 may be capable of connecting the second fuel gas opening 41b to the fuel gas discharge path 43, and also capable of connecting the second fuel gas opening 41b to the fuel gas supply path 42. In this case, it is easier to reverse the flow direction of the fuel gas Ga inside the fuel gas hole 41. For example, the opening diameter of the first joint 45 and the opening diameter of the second joint 46 may be the same.

[0058] The third joint 55 may be capable of connecting the first opening 51a for oxidizer gas to the oxidizer gas supply path 52, and also capable of connecting the first opening 51a for oxidizer gas to the oxidizer gas discharge path 53. The fourth joint 56 may be capable of connecting the second opening 51b for oxidizer gas to the oxidizer gas discharge path 53, and also capable of connecting the second opening 51b for oxidizer gas to the oxidizer gas supply path 52. In this case, it is easier to reverse the flow direction of the oxidizer gas Gc inside the oxidizer gas hole 51. For example, the opening diameter of the third joint 55 and the opening diameter of the fourth joint 56 may be the same.

[0059] The fifth joint 65 may be capable of connecting the first refrigerant opening 61a to the refrigerant supply path 62, and also capable of connecting the first refrigerant opening 61a to the refrigerant discharge path 63. The sixth joint 66 may be capable of connecting the second refrigerant opening 61b to the refrigerant discharge path 63, and also capable of connecting the second refrigerant opening 61b to the refrigerant supply path 62. In this case, it is easier to reverse the flow direction of refrigerant Mc inside the refrigerant hole 61. For example, the opening diameter of the fifth joint 65 and the opening diameter of the sixth joint 66 may be the same.

[0060] The shapes of the first joint 45 and the second joint 46 are not particularly limited. The shapes of the first joint 45 and the second joint 46 may be the same. The shapes of the third joint 55 and the fourth joint 56 are not particularly limited. The shapes of the third joint 55 and the fourth joint 56 may be the same. The shapes of the fifth joint 65 and the sixth joint 66 are not particularly limited. The shapes of the fifth joint 65 and the sixth joint 66 may be the same.

[0061] In Embodiment 1, the membrane electrode assembly 10 and the fuel cell cell 100 have a rectangular shape in plan view. The first side 10a of the membrane electrode assembly 10 and the first side 200a of the fuel cell stack 200 are the sides on which one of a pair of sides located perpendicular to the thickness direction of the membrane electrode assembly 10 is located. The second side 10b of the membrane electrode assembly 10 and the second side 200b of the fuel cell stack 200 are the sides on which the other of a pair of sides located perpendicular to the thickness direction of the membrane electrode assembly 10 is located. In the example of Figure 2, the ±X direction is the thickness direction of the membrane electrode assembly 10. The ±Y direction and ±Z direction are directions perpendicular to the thickness direction of the membrane electrode assembly 10, respectively. The ±Y direction and ±Z direction correspond to the surface direction of the membrane electrode assembly 10. In this specification, "surface direction of the membrane electrode assembly 10" means, for example, the direction in which the main surface of the membrane electrode assembly 10 extends.

[0062] The ±Z direction is, for example, a direction parallel to the vertical direction. The ±X direction is, for example, a direction parallel to the horizontal direction. The ±Y direction is, for example, a direction parallel to the horizontal direction and perpendicular to the thickness direction of the membrane electrode assembly 10. In the example of Figure 2, the first side 10a of the membrane electrode assembly 10 and the first side 200a of the fuel cell stack 200 are on the +X direction side. However, the first side 10a of the membrane electrode assembly 10 and the first side 200a of the fuel cell stack 200 may also be on the +Z direction side.

[0063] Figure 4 is a first plan view of the anode separator 20. The first plan view is a plan view of the surface 20p that is in contact with the anode 13. In Embodiment 1, the fuel gas flow path 40 is a meandering flow path including a plurality of first portions 401 and a plurality of second portions 402 provided in the planar direction. The first portion 401 is the portion that extends in the direction from the first portion 411 to the second portion 412 of the fuel gas hole 41. In the example of Figure 4, the first portion 401 has a straight shape in plan view. However, the first portion 401 may have an arc shape in plan view. The second portion 402 is the portion that extends in a direction perpendicular to the direction from the first portion 411 to the second portion 412 of the fuel gas hole 41. In the example of Figure 4, the second portion 402 has a straight shape in plan view. With such a configuration, fuel gas Ga can be supplied to every corner of the anode 13.

[0064] Figure 5 is a plan view of the cathode separator 30. In Embodiment 1, the oxidizing gas flow path 50 is a meandering flow path including a plurality of first portions 501 and a plurality of second portions 502 provided in the planar direction. The first portion 501 is the portion that extends in the direction from the first portion 511 to the second portion 512 of the oxidizing gas hole 51. In the example of Figure 5, the first portion 501 has a straight shape in plan view. However, the first portion 501 may have an arc shape in plan view. The second portion 502 is the portion that extends in a direction perpendicular to the direction from the first portion 511 to the second portion 512 of the oxidizing gas hole 51. In the example of Figure 5, the second portion 502 has a straight shape in plan view. With this configuration, the oxidizing gas Gc can be supplied to every corner of the cathode 16.

[0065] As can be seen from Figures 4 and 5, the flow direction of the fuel gas Ga flowing through the fuel gas channel 40 may be parallel to the flow direction of the oxidizer gas Gc flowing through the oxidizer gas channel 50. With this configuration, the electrochemical reaction in the membrane electrode assembly 10 can be carried out efficiently.

[0066] As can be seen from Figures 4 and 5, when the fuel cell cell 100 is viewed from a direction parallel to the thickness direction of the membrane electrode assembly 10, that is, when viewed from a transmitted plane, the flow direction of the fuel gas Ga in the second portion 402 of the fuel gas flow path 40 may be opposite to the flow direction of the oxidizer gas Gc in the second portion 502 of the oxidizer gas flow path 50. With such a configuration, the electrochemical reaction in the membrane electrode assembly 10 can be carried out efficiently.

[0067] The fuel cell stack 200 is installed, for example, so that the ±Z directions are parallel to the vertical direction. In this case, the second portion 402 of the fuel gas flow path 40 and the second portion 502 of the oxidizer gas flow path 50 are each parallel to the horizontal direction.

[0068] Figure 6 is a second plan view of the anode separator 20. The second plan view is a plan view of the surface 20q opposite to the surface 20p (Figure 4) that is in contact with the anode 13. In Embodiment 1, the refrigerant flow path 60 is a meandering flow path including a plurality of first portions 601 and a plurality of second portions 602 provided in the planar direction. The first portion 601 is the portion that extends in the direction from the first portion 611 to the second portion 612 of the refrigerant hole 61. In the example of Figure 6, the first portion 601 has a straight shape in plan view. However, the first portion 601 may have an arc shape in plan view. The second portion 602 is the portion that extends in a direction perpendicular to the direction from the first portion 611 to the second portion 612 of the refrigerant hole 61. In the example of Figure 6, the second portion 602 has a straight shape in plan view. With such a configuration, the membrane electrode assembly 10 can be cooled uniformly.

[0069] The above description refers to the case where the above structure or element includes at least one structure selected from the group consisting of structure A, structure B, and structure C, with reference to Figures 1 to 6. That is, as a configuration to obtain the above effects, a structure was described that makes it possible to perform at least one of the following actions without moving the fuel cell stack 200 itself: switching the fuel gas discharge path 43 and the fuel gas supply path 42, switching the oxidizer gas supply path 52 and the oxidizer gas discharge path 53, and switching the refrigerant supply path 62 and the refrigerant discharge path 63. However, the above structure or element is not limited to the example described above. Hereinafter, a modified example of the fuel cell system 300 of Embodiment 1 will be described.

[0070] (modified version) In the modified fuel cell system 300, the above structure or element includes the following structure D and at least one selected from the group consisting of the following structures E1, E2, and E3. (Structure D) A structure that allows the fuel cell stack 200 to be rotated and inverted with respect to the pivot axis FS. (Structure E1) A structure that, after inverting the fuel cell stack 200, allows a fuel gas discharge path 43 to be connected to the first fuel gas opening 41a and a fuel gas supply path 42 to the second fuel gas opening 41b. (Structure E2) A structure that allows the oxidizer gas discharge path 53 to be connected to the first opening 51a for oxidizer gas and the oxidizer gas supply path 52 to the second opening 51b for oxidizer gas after the fuel cell stack 200 has been inverted. (Structure E3) A structure that, after inverting the fuel cell stack 200, allows a refrigerant discharge path 63 to be connected to the first refrigerant opening 61a and a refrigerant supply path 62 to the second refrigerant opening 61b.

[0071] The pivot axis FS is a hypothetical axis that serves as the pivot point for the rotation of the fuel cell stack 200, extending parallel to the plane direction of the fuel cell cell 100. The pivot axis FS may extend parallel to the plane direction of the fuel cell cell 100 and be perpendicular to the axis X of the fuel cell stack 200. In this specification, the axis X of the fuel cell stack 200 means a straight line that extends parallel to the thickness direction of the fuel cell cell 100 and passes through the centroid of the main surface of the membrane electrode assembly 10.

[0072] Except that the above structure or element includes structure D below and at least one selected from the group consisting of structures E1, E2, and E3 below, the modified fuel cell system 300 has the same configuration as the fuel cell system 300 described above. Therefore, in the following, elements common to the fuel cell system 300 described above may be referred to by the same reference numerals and their descriptions may be omitted.

[0073] Figure 7A is a schematic cross-sectional view illustrating the first operating mode of the fuel cell system 300 in the modified example. Figure 7B is a schematic cross-sectional view illustrating the transition state from the first operating mode to the second operating mode of the fuel cell system 300 in the modified example. Figure 7C is a schematic cross-sectional view illustrating the second operating mode of the fuel cell system 300 in the modified example. Similar to Figures 3A and 3B, in Figures 7A to 7C, some elements are omitted for convenience so that the overall flow direction of the fuel gas Ga, the oxidizer gas Gc, and the refrigerant Mc during operation of the fuel cell system 300 in the modified example can be clearly understood.

[0074] As shown in Figure 7A, when the first operating mode is running, the flow direction of the fuel gas Ga inside the fuel gas holes 41, specifically the first section 411 and the second section 412, is from the first side 200a to the second side 200b. The flow direction of the oxidizer gas Gc inside the oxidizer gas holes 51, specifically the first section 511 and the second section 512, is from the second side 200b to the first side 200a. The flow direction of the refrigerant Mc inside the refrigerant holes 61, specifically the first section 611 and the second section 612, is from the second side 200b to the first side 200a.

[0075] If the above structure or element includes structure D and at least one selected from the group consisting of structure E1, structure E2, and structure E3, then at least one selected from the group consisting of the flow direction of fuel gas Ga inside the fuel gas hole 41, the flow direction of oxidant gas Gc inside the oxidant gas hole 51, and the flow direction of refrigerant Mc inside the refrigerant hole 61 can be reversed.

[0076] Structure D includes, for example, a structure in which the fuel cell stack 200 has a rotation mechanism that rotatably supports the fuel cell stack 200 with respect to a pivot axis FS.

[0077] By including structure D, the fuel cell stack 200 can be rotated around the pivot axis FS as shown in Figure 7B, and the fuel cell stack 200 can be inverted, for example, by 180° as shown in Figure 7C. In the modified fuel cell system 300, as shown in Figure 7B, when rotating the fuel cell stack 200, the connection of the fuel gas supply path 42 to the first fuel gas opening 41a and the connection of the fuel gas supply path 42 to the second fuel gas opening 41b are disconnected. Similarly, the connection of the oxidizer gas supply path 52 to the first oxidizer gas opening 51a and the connection of the oxidizer gas discharge path 53 to the second oxidizer gas opening 51b are disconnected. Similarly, the connection of the refrigerant supply path 62 to the first refrigerant opening 61a and the connection of the refrigerant discharge path 63 to the second refrigerant opening 61b are disconnected.

[0078] Structure E1 includes, for example, a structure in which the diameter of the first opening 41a for fuel gas and the diameter of the second opening 41b for fuel gas are the same. Structure E2 includes, for example, a structure in which the diameter of the first opening 51a for oxidizer gas and the diameter of the second opening 51b for oxidizer gas are the same. Structure E3 includes, for example, a structure in which the diameter of the first opening 61a for refrigerant and the diameter of the second opening 61b for refrigerant are the same.

[0079] If structure E1 is included, as shown in Figure 7C, after inverting the fuel cell stack 200 by, for example, 180°, a fuel gas discharge path 43 can be connected to the first fuel gas opening 41a and a fuel gas supply path 42 can be connected to the second fuel gas opening 41b. If structure E2 is included, as shown in Figure 7C, after inverting the fuel cell stack 200 by, for example, 180°, an oxidizer gas discharge path 53 can be connected to the first oxidizer gas opening 51a and an oxidizer gas supply path 52 can be connected to the second oxidizer gas opening 51b. If structure E3 is included, as shown in Figure 7C, after inverting the fuel cell stack 200 by, for example, 180°, a refrigerant discharge path 63 can be connected to the first refrigerant opening 61a and a refrigerant supply path 62 can be connected to the second refrigerant opening 61b. As a result, as shown in Figure 7C, when the second operating mode is executed, the flow direction of the fuel gas Ga inside the fuel gas holes 41, specifically the second section 412 and the first section 411, can be switched from the second side 200b to the first side 200a. The flow direction of the oxidizer gas Gc inside the oxidizer gas holes 51, specifically the second section 512 and the first section 511, can be switched from the first side 200a to the second side 200b. The flow direction of the refrigerant Mc inside the refrigerant holes 61, specifically the second section 612 and the first section 611, can be switched from the first side 200a to the second side 200b. Therefore, even if the metal ion content in the ±Z direction of the electrolyte membrane 12 becomes uneven by executing the first operating mode for a certain period of time, the metal ion content in the ±Z direction of the electrolyte membrane 12 can be made uniform by executing the second operating mode.

[0080] Furthermore, the phrase "a structure in which the fuel cell stack 200 can be inverted so as to rotate it with respect to the pivot axis FS" in structure D does not necessarily mean that the fuel cell stack 200 is inverted by 180° with respect to the pivot axis FS.

[0081] Figure 8(A) is a plan view along the thickness direction of the fuel cell stack 200 before inversion. Figure 8(B) is a plan view along the thickness direction of the fuel cell stack 200 after inversion. Figure 8(C) is a plan view of (A) and (B) superimposed. As shown in Figure 8(C), the modified fuel cell system 300 may satisfy at least one selected from the group consisting of (i), (ii), and (iii) below in a plan view along the thickness direction. However, the fuel cell stack 200 is not translated, and the inverted fuel cell stack 200 is appropriately positioned in the location where the fuel cell stack 200 was located before inversion. (i) The first fuel gas opening 41a before the fuel cell stack 200 is inverted and the second fuel gas opening 41b after the fuel cell stack 200 is inverted overlap. (ii) The first opening 51a for the oxidizer gas before the fuel cell stack 200 is inverted and the second opening 51b for the oxidizer gas after the fuel cell stack 200 is inverted overlap. (iii) The first refrigerant opening 61a before the fuel cell stack 200 is inverted and the second refrigerant opening 61b after the fuel cell stack 200 is inverted overlap.

[0082] If (i) is satisfied, the fuel gas discharge path 43 and the fuel gas supply path 42 can be reversed without changing the design of the fuel gas supply path 42 and the fuel gas discharge path 43. If (ii) is satisfied, the oxidizer gas supply path 52 and the oxidizer gas discharge path 53 can be reversed without changing the design of the oxidizer gas supply path 52 and the oxidizer gas discharge path 53. If (iii) is satisfied, the refrigerant supply path 62 and the refrigerant discharge path 63 can be reversed without changing the design of the refrigerant supply path 62 and the refrigerant discharge path 63. Therefore, at least one selected from the group consisting of the flow direction of fuel gas Ga inside the fuel gas hole 41, the flow direction of oxidizer gas Gc inside the oxidizer gas hole 51, and the flow direction of refrigerant Mc inside the refrigerant hole 61 can be reversed more easily.

[0083] As shown in Figure 2, the fuel cell stack 200 may further include a first current collector plate 71 located on the first side 100a of a plurality of fuel cell cells 100, a second current collector plate 72 located on the second side 100b of a plurality of fuel cell cells 100, a pair of first terminals 71a, 71b for power extraction protruding from one opposite side of the first current collector plate 71, and a pair of second terminals 72a, 72b for power extraction protruding from one opposite side of the second current collector plate 72. A plurality of fuel cell cells 100 may be sandwiched between the first current collector plate 71 and the second current collector plate 72. Such a structure is particularly effective for a modified fuel cell system 300.

[0084] In conventional fuel cell stacks, terminals for power extraction are located on the upper part of current collector plates positioned on both sides of multiple fuel cell cells (see, for example, Figure 2 of Patent Document 1). This is because connecting the power harness to the upper part of the fuel cell stack allows for a shorter power harness length compared to connecting it to the lower part of the fuel cell stack, thereby suppressing a decrease in power generation efficiency. Therefore, for example, when performing the first operating mode shown in Figure 7A, the first terminal 71a and the second terminal 72a, located at the upper part of the fuel cell stack 200, are typically used.

[0085] If the fuel cell stack 200 is equipped with a pair of first terminals 71a and 71b for power extraction, each protruding from one opposite side of the first current collector plate 71, and a pair of second terminals 72a and 72b for power extraction, each protruding from one opposite side of the second current collector plate 72, then, for example, as shown in Figure 7C, the first terminals 71b and 72b are located at the top of the fuel cell stack 200 even when the second operating mode is performed after the fuel cell stack 200 has been rotated 180°. Therefore, a power harness can be easily connected to the first terminals 71b and 72b located at the top.

[0086] The direction in which the pair of first terminals 71a and 71b extend and the direction in which the pair of second terminals 72a and 72b extend may be the same. As shown in Figure 2, the direction in which the pair of first terminals 71a and 71b extend and the direction in which the pair of second terminals 72a and 72b extend may both be in the ±Z direction. With such a structure, for example, as shown in Figure 7C, it is easy to position the first terminals 71b and the second terminals 72b on top of the fuel cell stack 200 after inverting the fuel cell stack 200 by 180°.

[0087] A power harness may be detachably attached to one of the pair of first terminals 71a and 71b, and an insulator may be detachably attached to the other of the pair of first terminals 71a and 71b. A power harness may be detachably attached to one of the pair of second terminals 72a and 72b, and an insulator may be detachably attached to the other of the pair of second terminals 72a and 72b. With such a structure, terminals that are not used during the operation of the fuel cell system 300 can be insulated.

[0088] Examples of insulators include insulating caps that cover terminals. The shape of the insulating cap is not particularly limited, as long as it can insulate the terminals. For example, an insulating resin can be used as the material for the insulating cap.

[0089] A power harness detachably attached to one of a pair of first terminals 71a, 71b may also be detachably attached to the other of the pair of first terminals 71a, 71b. An insulator detachably attached to one of a pair of first terminals 71a, 71b may also be detachably attached to the other of the pair of first terminals 71a, 71b. A power harness detachably attached to one of a pair of second terminals 72a, 72b may also be detachably attached to the other of the pair of second terminals 72a, 72b. An insulator detachably attached to one of a pair of second terminals 72a, 72b may also be detachably attached to the other of the pair of second terminals 72a, 72b.

[0090] As shown in Figure 2, the fuel cell stack 200 further comprises a first insulating plate 81 positioned outside the first current collector plate 71, a second insulating plate 82 positioned outside the second current collector plate 72, a first fastening plate 91 positioned outside the first insulating plate 81, and a second fastening plate 92 positioned outside the second insulating plate 82. Although not shown, the fuel cell stack 200 is constructed by fastening the first fastening plate 91 and the second fastening plate 92 with bolts and nuts.

[0091] As shown in Figure 1, the fuel cell system 300 in Embodiment 1 further comprises an electrical component group 210 in addition to the fuel cell stack 200. The electrical component group 210 includes a control board and a communication device. It can also be considered that the power generation unit 250 is composed of the fuel cell stack 200 and the electrical component group 210. The control board is a circuit board for controlling various devices of the power generation unit 250. The communication device is a device for performing necessary data communication with the control board.

[0092] As shown in Figure 1, the fuel gas supply path 42 may, for example, lead fuel gas Ga from a fuel gas supply source 110 installed outside the fuel cell system 300 to the fuel cell stack 200. Examples of the fuel gas supply source 110 include a hydrogen-containing gas storage tank and a reformer. The oxidizer gas supply path 52 may, for example, lead oxidizer gas Gc from an oxidizer gas inlet 120 installed outside the fuel cell system 300 to the fuel cell stack 200. An air blower or fan may be provided at the oxidizer gas inlet 120. The refrigerant supply path 62 may, for example, lead refrigerant Mc from a refrigerant supply source 130 installed outside the fuel cell system 300 to the fuel cell stack 200. Examples of the refrigerant supply source 130 include a refrigerant Mc storage tank.

[0093] [1-2. Operation] The operation and function of the fuel cell system 300, configured as described above, will be explained below with reference to Figures 1 to 8.

[0094] (Operation method of fuel cell system 300) The operating method of the fuel cell system 300 includes a first operating step and a second operating step. The first operating step is the step corresponding to the first operating mode described above. The second operating step is the step corresponding to the second operating mode described above.

[0095] The first operating step of the fuel cell system 300 is to circulate fuel gas Ga through the fuel gas port 41, oxidant gas Gc through the oxidant gas port 51, and refrigerant Mc through the refrigerant port 61. In the first operating step, fuel gas Ga supplied from the fuel gas supply path 42 is introduced into the first portion 411 of the fuel gas port 41. Oxidant gas Gc supplied from the oxidant gas supply path 52 is introduced into the first portion 511 of the oxidant gas port 51. Refrigerant Mc supplied from the refrigerant supply path 62 is introduced into the first portion 611 of the refrigerant port 61. Oxidant gas Gc is typically air.

[0096] As shown in Figure 2A, in the first operating step, the flow direction of the fuel gas Ga inside the fuel gas holes 41, specifically the first section 411 and the second section 412, is from the first side 200a to the second side 200b. The flow direction of the oxidizer gas Gc inside the oxidizer gas holes 51, specifically the first section 511 and the second section 512, is from the second side 200b to the first side 200a. The flow direction of the refrigerant Mc inside the refrigerant holes 61, specifically the first section 611 and the second section 612, is from the second side 200b to the first side 200a.

[0097] At anode 13, in the electrochemical reaction represented by the following equation (1), hydrogen (H2) is converted into proton (H2). + ) and electrons (e - The two separate. Protons move from the anode 13 to the cathode 16 by conducting through the electrolyte membrane 12. Electrons move from the anode 13 to the cathode 16 through the external circuit. At the cathode 16, water (H2O) is produced by an electrochemical reaction involving protons, oxygen (O2), and electrons, as shown in equation (2) below.

[0098] H2→2H + +2e - (1) 4H + +O2+4e - →2H2O(2)

[0099] As described above, the electrolyte membrane 12 contains metal ions. Therefore, if the first operation step is continued, a bias in the water content will occur in the planar direction of the electrolyte membrane 12, particularly in the ±Z direction, and consequently, a bias in the metal ion content of the electrolyte membrane 12 in the ±Z direction may also occur. If a bias in the metal ion content of the electrolyte membrane 12 in the ±Z direction occurs after performing the first operation step for a certain period of time, the process will proceed to the second operation step.

[0100] The second operating step of the fuel cell system 300 includes, after performing the first operating step, reversing at least one selected from the group consisting of the flow direction of fuel gas Ga inside the fuel gas port 41, the flow direction of oxidizer gas Gc inside the oxidizer gas port 51, and the flow direction of refrigerant Mc inside the refrigerant port 61.

[0101] According to the second operating step, even if there is a bias in the metal ion content of the electrolyte membrane 12 in the ±Z direction, at least one selected from the group consisting of the flow direction of fuel gas Ga inside the fuel gas holes 41, the flow direction of oxidant gas Gc inside the oxidant gas holes 51, and the flow direction of refrigerant Mc inside the refrigerant holes 61 can be reversed. Reversing the flow direction of fuel gas Ga inside the fuel gas holes 41 reverses the flow direction of fuel gas Ga inside the fuel gas flow path 40. Reversing the flow direction of oxidant gas Gc inside the oxidant gas holes 51 reverses the flow direction of oxidant gas Gc inside the oxidant gas flow path 50. Reversing the flow direction of refrigerant Mc inside the refrigerant holes 61 reverses the flow direction of refrigerant Mc inside the refrigerant flow path 60. As a result, the moisture content of the electrolyte membrane 12 in the ±Z direction can be made uniform, and therefore the metal ion content of the electrolyte membrane 12 in the ±Z direction can also be made uniform. As a result, the ability to avoid radical attack can be maintained, and the durability of the electrolyte membrane 12 can be improved.

[0102] In this specification, "second operating step" may be read as "maintenance method." The maintenance method for the fuel cell system 300 includes, after performing a first operation in which fuel gas Ga is circulated through fuel gas holes 41, oxidizer gas Gc is circulated through oxidizer gas holes 51, and refrigerant Mc is circulated through refrigerant holes 61, reversing at least one selected from the group consisting of the flow direction of fuel gas Ga inside the fuel gas holes 41, the flow direction of oxidizer gas Gc inside the oxidizer gas holes 51, and the flow direction of refrigerant Mc inside the refrigerant holes 61 (step S11).

[0103] The above reversal involves reversing at least one selected from the group consisting of the flow direction of fuel gas Ga in the first opening 41a for fuel gas, the flow direction of oxidant gas Gc in the first opening 51a for oxidant gas, and the flow direction of refrigerant Mc in the first opening 61a for refrigerant. As a result, even if there is a bias in the metal ion content of the electrolyte membrane 12 in the ±Z direction, the water content of the electrolyte membrane 12 in the ±Z direction can be made uniform, and therefore the metal ion content of the electrolyte membrane 12 in the ±Z direction can also be made uniform.

[0104] The above inversion may include at least one selected from the group consisting of substeps A, B, and C below. (Substep A) Connect the fuel gas discharge path 43 to the first fuel gas opening 41a and the fuel gas supply path 42 to the second fuel gas opening 41b. (Substep B) Connect the oxidant gas discharge path 53 to the first opening 51a for the oxidant gas, and connect the oxidant gas supply path 52 to the second opening 51b for the oxidant gas. (Substep C) Connect the refrigerant discharge path 63 to the first refrigerant opening 61a and the refrigerant supply path 62 to the second refrigerant opening 61b.

[0105] In this case, without changing the configuration of the fuel cell system 300, at least one selected from the group consisting of the flow direction of fuel gas Ga inside the fuel gas port 41, the flow direction of oxidant gas Gc inside the oxidant gas port 51, and the flow direction of refrigerant Mc inside the refrigerant port 61 can be reversed. Therefore, the cost required to obtain the above-mentioned effects can be reduced.

[0106] (Operation method of fuel cell system 300 in a modified example) The operating method of the fuel cell system 300 in the modified example includes a first operating step and a second operating step. The first operating step is the same as the first operating step of the fuel cell system 300, so its explanation is omitted.

[0107] In the modified example, the second operating step of the fuel cell system 300 includes the following substep D and at least one selected from the group consisting of the following substeps E1, E2, and E3. (Substep D) Invert the fuel cell stack 200 so that it rotates with respect to the pivot axis FS. (Substep E1) After inverting the fuel cell stack 200, connect the fuel gas discharge path 43 to the first fuel gas opening 41a and connect the fuel gas supply path 42 to the second fuel gas opening 41b. (Substep E2) After inverting the fuel cell stack 200, connect the oxidant gas discharge path 53 to the first oxidant gas opening 51a and connect the oxidant gas supply path 52 to the second oxidant gas opening 51b. (Substep E3) After inverting the fuel cell stack 200, connect the refrigerant discharge path 63 to the first refrigerant opening 61a and connect the refrigerant supply path 62 to the second refrigerant opening 61b.

[0108] If the above reversal includes substep D and at least one selected from the group consisting of substeps E1, E2, and E3, then at least one selected from the group consisting of the flow direction of fuel gas Ga inside the fuel gas hole 41, the flow direction of oxidant gas Gc inside the oxidant gas hole 51, and the flow direction of refrigerant Mc inside the refrigerant hole 61 can be reversed. Therefore, even if the metal ion content in the ±Z direction of the electrolyte membrane 12 becomes uneven by performing the first operation step for a certain period of time, the metal ion content in the ±Z direction of the electrolyte membrane 12 can be made uniform by performing the second operation step.

[0109] Embodiment 1 described a fuel cell system 300 comprising a fuel cell stack 200 containing a plurality of fuel cell cells 100, using Figures 1 to 8. However, the configuration of the fuel cell system according to the present invention is not limited to the examples shown in Figures 1 to 8. The fuel cell system according to the present invention only needs to have at least one fuel cell stack 200. At least one fuel cell stack 200 may include a plurality of fuel cell stacks 200. Embodiment 2 below will describe the case in which at least one fuel cell stack 200 includes a plurality of fuel cell stacks 200.

[0110] (Embodiment 2) Embodiment 2 will be described below with reference to Figures 9 to 11.

[0111] [2-1. Structure] Figure 9 is a block diagram showing the configuration of the fuel cell system 400 in Embodiment 2. Figure 10 is a partial schematic cross-sectional view of the fuel cell system 400 in Embodiment 2. In the fuel cell system 400, the fuel cell stack 200 includes a first fuel cell stack 201 and a second fuel cell stack 202. The first fuel cell stack 201 and the second fuel cell stack 202 each include a plurality of fuel cell cells 100. In the fuel cell system 400, the above structure or element includes a structure F that allows the first fuel cell stack 201 and the second fuel cell stack 202 to be interchangeable.

[0112] In the example shown in Figure 9, the fuel cell system 400 includes a first subsystem 301 having a first fuel cell stack 201 and a second subsystem 302 having a second fuel cell stack 202.

[0113] At least one selected from the group consisting of the flow direction of fuel gas Ga inside the fuel gas hole 41, the flow direction of oxidizer gas Gc inside the oxidizer gas hole 51, and the flow direction of refrigerant Mc inside the refrigerant hole 61 in the first subsystem 301 is opposite to at least one selected from the group consisting of the flow direction of fuel gas Ga inside the fuel gas hole 41, the flow direction of oxidizer gas Gc inside the oxidizer gas hole 51, and the flow direction of refrigerant Mc inside the refrigerant hole 61 in the second subsystem 302.

[0114] In the examples of Figures 9 and 10, the first subsystem 301 has the same structure as the fuel cell system 300 in Figure 3A. The second subsystem 302 has the same structure as the fuel cell system 300 in Figure 3B. That is, in the first subsystem 301, the flow direction of the fuel gas Ga inside the fuel gas port 41 is from the first side 200a to the second side 200b. The flow direction of the oxidizer gas Gc inside the oxidizer gas port 51 is from the second side 200b to the first side 200a. The flow direction of the refrigerant Mc inside the refrigerant port 61 is from the second side 200b to the first side 200a. In the second subsystem 302, the flow direction of the fuel gas Ga inside the fuel gas port 41 is from the second side 200b to the first side 200a. The flow direction of the oxidizer gas Gc inside the oxidizer gas port 51 is from the first side 200a to the second side 200b. The flow direction of the refrigerant Mc inside the refrigerant hole 61 is from the first side 200a to the second side 200b.

[0115] According to the fuel cell system 400, by swapping the first fuel cell stack 201 and the second fuel cell stack 202, at least one selected from the group consisting of the flow direction of fuel gas Ga inside the fuel gas holes 41, the flow direction of oxidant gas Gc inside the oxidant gas holes 51, and the flow direction of refrigerant Mc inside the refrigerant holes 61 can be reversed in each of the first fuel cell stack 201 and the second fuel cell stack 202. Therefore, for example, no special design is required to reverse the first fuel cell stack 201 and the second fuel cell stack 202. In this specification, "a structure F in which the first fuel cell stack 201 and the second fuel cell stack 202 can be swapped" means, for example, a structure in which the supply paths and discharge paths can be reconnected without reversing either the first fuel cell stack 201 or the second fuel cell stack 202 by rotating them with respect to a pivot axis FS.

[0116] Figure 10 also serves as a schematic cross-sectional view illustrating the first operating mode of the fuel cell system 400. Figure 11 is a schematic cross-sectional view illustrating the second operating mode of the fuel cell system 400 shown in Figure 10. In Figures 10 and 11, some elements are omitted for convenience so that the overall flow direction of the fuel gas Ga, the oxidizer gas Gc, and the refrigerant Mc during operation of the fuel cell system 400 can be clearly understood.

[0117] As shown in Figure 10, when the first operating mode is executed, the first fuel cell stack 201 is connected to the first subsystem 301, and the second fuel cell stack 202 is connected to the second subsystem 300b. The flow direction of the fuel gas Ga in the fuel gas holes 41 in the first fuel cell stack 201, specifically in the first section 411 and the second section 412, is from the first side 200a to the second side 200b. The flow direction of the oxidizer gas Gc in the oxidizer gas holes 51 in the first fuel cell stack 201, specifically in the first section 511 and the second section 512, is from the second side 200b to the first side 200a. The flow direction of the refrigerant Mc in the refrigerant holes 61 in the first fuel cell stack 201, specifically in the first section 611 and the second section 612, is from the second side 200b to the first side 200a. On the other hand, the flow direction of the fuel gas Ga inside the fuel gas holes 41 in the second fuel cell stack 202, specifically the first section 411 and the second section 412, is from the second side 200b toward the first side 200a. The flow direction of the oxidizer gas Gc inside the oxidizer gas holes 51 in the second fuel cell stack 202, specifically the first section 511 and the second section 512, is from the first side 200a toward the second side 200b. The flow direction of the refrigerant Mc inside the refrigerant holes 61 in the second fuel cell stack 202, specifically the first section 611 and the second section 612, is from the first side 200a toward the second side 200b.

[0118] In the fuel cell system 400, the above structure or element includes a structure F that allows the first fuel cell stack 201 and the second fuel cell stack 202 to be swapped, thereby enabling the swapping of the first fuel cell stack 201 and the second fuel cell stack 202. That is, the second fuel cell stack 202 can be connected to the first subsystem 301, and the first fuel cell stack 201 can be connected to the second subsystem 302. As a result, as shown in Figure 11, when the second operating mode is executed, the flow direction of the fuel gas Ga inside the fuel gas holes 41 in the first fuel cell stack 201, specifically the second section 412 and the first section 411, can be switched from the second side 200b to the first side 200a. The flow direction of the oxidizer gas Gc inside the oxidizer gas holes 51 in the first fuel cell stack 201, specifically the second section 512 and the first section 511, can be switched from the first side 200a to the second side 200b. The flow direction of refrigerant Mc inside the refrigerant holes 61 in the first fuel cell stack 201, specifically the second section 612 and the first section 611, can be switched from the direction toward the first side 200a to the direction toward the second side 200b. On the other hand, the flow direction of fuel gas Ga inside the fuel gas holes 41 in the second fuel cell stack 202, specifically the second section 412 and the first section 411, can be switched from the direction toward the first side 200a to the direction toward the second side 200b. The flow direction of oxidizer gas Gc inside the oxidizer gas holes 51 in the second fuel cell stack 202, specifically the second section 512 and the first section 511, can be switched from the direction toward the second side 200b to the direction toward the first side 200a. The flow direction of refrigerant Mc inside the refrigerant holes 61 in the second fuel cell stack 202, specifically the second section 612 and the first section 611, can be switched from the direction toward the second side 200b to the direction toward the first side 200a. Therefore, even if the metal ion content in the electrolyte membrane 12 of the first fuel cell stack 201 and the second fuel cell stack 202 becomes uneven in the ±Z direction by running the first operating mode for a certain period of time, the metal ion content in the ±Z direction of the electrolyte membrane 12 of the first fuel cell stack 201 and the second fuel cell stack 202 can be made uniform by running the second operating mode.

[0119] As shown in Figure 10, when the first operating mode is executed, the flow direction of the fuel gas Ga inside the fuel gas port 41, the flow direction of the oxidizer gas Gc inside the oxidizer gas port 51, and the flow direction of the refrigerant Mc inside the refrigerant port 61 in the first subsystem 301 may be opposite to the flow direction of the fuel gas Ga inside the fuel gas port 41, the flow direction of the oxidizer gas Gc inside the oxidizer gas port 51, and the flow direction of the refrigerant Mc inside the refrigerant port 61 in the second subsystem 302.

[0120] As shown in Figure 9, the fuel cell system 400 in Embodiment 2 further comprises an electrical component group 211 and an electrical component group 212, in addition to the first fuel cell stack 201 and the second fuel cell stack 202. Each of the electrical component group 211 and the electrical component group 212 includes a control board and a communication device. The first power generation unit 251 can be considered to be composed of the first fuel cell stack 201 and the electrical component group 211. The second power generation unit 252 can be considered to be composed of the second fuel cell stack 202 and the electrical component group 212. The control board is a circuit board for controlling various devices of the first power generation unit 251 and the second power generation unit 252. The communication device is a device for performing necessary data communication with the control board.

[0121] As shown in Figure 9, the fuel gas supply path 42 in the first subsystem 301 may lead fuel gas Ga from a fuel gas supply source 111 located outside the first subsystem 301 to the first fuel cell stack 201. The fuel gas supply path 42 in the second subsystem 302 may lead fuel gas Ga from a fuel gas supply source 112 located outside the second subsystem 302 to the second fuel cell stack 202. Examples of fuel gas supply sources 111 and 112 include storage tanks for hydrogen-containing gas. The oxidizer gas supply path 52 in the first subsystem 301 may lead oxidizer gas Gc from an oxidizer gas inlet 121 located outside the first subsystem 301 to the first fuel cell stack 201. The oxidizer gas supply path 52 in the second subsystem 302 may lead oxidizer gas Gc from an oxidizer gas inlet 122 located outside the second subsystem 302 to the second fuel cell stack 202. An air blower or fan may be provided at the oxidizer gas inlets 121 and 122, respectively. The refrigerant supply path 62 in the first subsystem 301 may lead refrigerant Mc from a refrigerant supply source 131 located outside the first subsystem 301 to the first fuel cell stack 201. The refrigerant supply path 62 in the second subsystem 302 may lead refrigerant Mc from a refrigerant supply source 132 located outside the second subsystem 302 to the second fuel cell stack 202. Examples of refrigerant supply sources 131 and 132 include refrigerant Mc storage tanks.

[0122] However, the fuel gas supply path 42 connected to the first fuel cell stack 201 and the fuel gas supply path 42 connected to the second fuel cell stack 202 may be connected to a common fuel gas supply source. The oxidizer gas supply path 52 connected to the first fuel cell stack 201 and the oxidizer gas supply path 52 connected to the second fuel cell stack 202 may be connected to a common oxidizer gas inlet. The refrigerant supply path 62 connected to the first fuel cell stack 201 and the refrigerant supply path 62 connected to the second fuel cell stack 202 may be connected to a common refrigerant supply source.

[0123] [2-2. Operation] The operation and function of the fuel cell system 400, configured as described above, will be explained below with reference to Figures 9 to 11.

[0124] The operating method of the fuel cell system 400 includes a first operating step and a second operating step. The first operating step is the step corresponding to the first operating mode described above. The second operating step is the step corresponding to the second operating mode described above.

[0125] The first operating step of the fuel cell system 400 is to circulate fuel gas Ga through the fuel gas port 41, oxidizer gas Gc through the oxidizer gas port 51, and refrigerant Mc through the refrigerant port 61 in each of the first fuel cell stack 201 and the second fuel cell stack 202. In the first operating step, in each of the first fuel cell stack 201 and the second fuel cell stack 202, fuel gas Ga supplied from the fuel gas supply path 42 is introduced into the first portion 411 of the fuel gas port 41. In each of the first fuel cell stack 201 and the second fuel cell stack 202, oxidizer gas Gc supplied from the oxidizer gas supply path 52 is introduced into the first portion 511 of the oxidizer gas port 51. In each of the first fuel cell stack 201 and the second fuel cell stack 202, refrigerant Mc supplied from the refrigerant supply path 62 is introduced into the first portion 611 of the refrigerant port 61.

[0126] As shown in Figure 10, in the first operating step, the first subsystem 301 is connected to the first fuel cell stack 201, and the second subsystem 302 is connected to the second fuel cell stack 202. The flow direction of the fuel gas Ga in the fuel gas holes 41 in the first fuel cell stack 201, specifically in the first section 411 and the second section 412, is from the first side 200a to the second side 200b. The flow direction of the oxidizer gas Gc in the oxidizer gas holes 51 in the first fuel cell stack 201, specifically in the first section 511 and the second section 512, is from the second side 200b to the first side 200a. The flow direction of the refrigerant Mc in the refrigerant holes 61 in the first fuel cell stack 201, specifically in the first section 611 and the second section 612, is from the second side 200b to the first side 200a. On the other hand, the flow direction of the fuel gas Ga inside the fuel gas holes 41 in the second fuel cell stack 202, specifically the first section 411 and the second section 412, is from the second side 200b toward the first side 200a. The flow direction of the oxidizer gas Gc inside the oxidizer gas holes 51 in the second fuel cell stack 202, specifically the first section 511 and the second section 512, is from the first side 200a toward the second side 200b. The flow direction of the refrigerant Mc inside the refrigerant holes 61 in the second fuel cell stack 202, specifically the first section 611 and the second section 612, is from the first side 200a toward the second side 200b.

[0127] If, after performing the first operation step for a certain period, an imbalance occurs in the metal ion content of the electrolyte membrane 12 in the ±Z direction of the first fuel cell stack 201 and the second fuel cell stack 202, the system proceeds to the second operation step.

[0128] In the second operating step of the fuel cell system 400, after performing the first operating step, the first fuel cell stack 201 and the second fuel cell stack 202 are swapped by reversing at least one selected from the group consisting of the flow direction of fuel gas Ga inside the fuel gas port 41, the flow direction of oxidant gas Gc inside the oxidant gas port 51, and the flow direction of refrigerant Mc inside the refrigerant port 61.

[0129] According to the second operating step, even if there is a bias in the metal ion content of the electrolyte membrane 12 in the ±Z direction in the first fuel cell stack 201 and the second fuel cell stack 202, at least one selected from the group consisting of the flow direction of fuel gas Ga inside the fuel gas hole 41, the flow direction of oxidant gas Gc inside the oxidant gas hole 51, and the flow direction of refrigerant Mc inside the refrigerant hole 61 in the first fuel cell stack 201, and at least one selected from the group consisting of the flow direction of fuel gas Ga inside the fuel gas hole 41, the flow direction of oxidant gas Gc inside the oxidant gas hole 51, and the flow direction of refrigerant Mc inside the refrigerant hole 61 in the second fuel cell stack 202 can be reversed. By reversing the bias in the water content of the electrolyte membrane 12 in the ±Z direction in the first fuel cell stack 201 and the second fuel cell stack 202, the direction of movement of metal ions in the electrolyte membrane 12 in the first fuel cell stack 201 and the second fuel cell stack 202 can be reversed, and the metal ion content in the ±Z direction can be made uniform. As a result, the ability to avoid radical attack can be maintained, thereby improving the durability of the electrolyte membrane 12 in the first fuel cell stack 201 and the second fuel cell stack 202.

[0130] As described above, in this specification, “second operation step” can be read as “maintenance method.” The maintenance method for the fuel cell system 400 includes, after performing the first operation, swapping the first fuel cell stack 201 and the second fuel cell stack 202 to reverse at least one selected from the group consisting of the flow direction of fuel gas Ga inside the fuel gas holes 41, the flow direction of oxidant gas Gc inside the oxidant gas holes 51 and the flow direction of refrigerant Mc inside the refrigerant holes 61 in the first fuel cell stack 201, and at least one selected from the group consisting of the flow direction of fuel gas Ga inside the fuel gas holes 41, the flow direction of oxidant gas Gc inside the oxidant gas holes 51 and the flow direction of refrigerant Mc inside the refrigerant holes 61 in the second fuel cell stack 202 (step S21).

[0131] The descriptions of each embodiment and each modification described above are interchangeable, insofar as they do not conflict technically. Furthermore, each embodiment and each modification may be combined with each other, insofar as they do not conflict technically.

[0132] (Note) Based on the above description of embodiments, the following technologies are disclosed.

[0133] (Technology 1) A fuel cell stack comprising a plurality of fuel cell cells, and having fuel gas holes, oxidizer gas holes, and refrigerant holes formed therein that extend in the thickness direction of the fuel cell cells and penetrate the plurality of fuel cell cells, A structure or element that reverses at least one selected from the group consisting of the fuel gas flow direction inside the fuel gas hole, the oxidizer gas flow direction inside the oxidizer gas hole, and the refrigerant flow direction inside the refrigerant hole, Equipped with, The fuel cell includes a membrane electrode assembly comprising an anode, a cathode, and an electrolyte membrane containing metal ions. Fuel cell system.

[0134] This configuration can improve the durability of the electrolyte membrane containing metal ions.

[0135] (Technology 2) A fuel gas supply path connected to a first fuel gas opening located at one end of the fuel gas hole; a fuel gas discharge path connected to a second fuel gas opening located at the other end of the fuel gas hole; an oxidant gas supply path connected to a first oxidant gas opening located at one end of the oxidant gas hole; an oxidant gas discharge path connected to a second oxidant gas opening located at the other end of the oxidant gas hole; a refrigerant supply path connected to a first refrigerant opening located at one end of the refrigerant hole; and a refrigerant discharge path connected to a second refrigerant opening located at the other end of the refrigerant hole. A fuel cell system according to Technology 1, further comprising a path, wherein the structure or element includes at least one selected from the group consisting of: a structure capable of connecting the fuel gas discharge path to the first opening for fuel gas and the fuel gas supply path to the second opening for fuel gas; a structure capable of connecting the oxidizer gas discharge path to the first opening for oxidizer gas and the oxidizer gas supply path to the second opening for oxidizer gas; and a structure capable of connecting the refrigerant discharge path to the first opening for refrigerant and the refrigerant supply path to the second opening for refrigerant. With such a configuration, the cost required to obtain the above-mentioned effects can be reduced.

[0136] (Technology 3) The fuel cell system according to Technology 1 or 2, wherein the structure or element includes at least one selected from the group consisting of: a structure capable of inverting the fuel cell stack so as to rotate it with respect to a pivot axis; a structure capable of connecting the fuel gas discharge path to the first opening for fuel gas and the fuel gas supply path to the second opening for fuel gas after the fuel cell stack has been inverted; a structure capable of connecting the oxidizer gas discharge path to the first opening for oxidizer gas and the oxidizer gas supply path to the second opening for oxidizer gas after the fuel cell stack has been inverted; and a structure capable of connecting the refrigerant discharge path to the first opening for refrigerant and the refrigerant supply path to the second opening for refrigerant after the fuel cell stack has been inverted. With such a configuration, even if a bias occurs in the metal ion content in the planar direction of the electrolyte membrane by running the first operating mode for a certain period of time, the metal ion content in the planar direction of the electrolyte membrane can be made uniform by running the second operating mode.

[0137] (Technology 4) The fuel cell system according to Technology 3, wherein, in a plan view along the thickness direction, it satisfies at least one selected from the group consisting of (i), (ii), and (iii) below. (i) The first opening for fuel gas before the fuel cell stack is inverted and the second opening for fuel gas after the fuel cell stack is inverted overlap. (ii) The first opening for the oxidizer gas before the fuel cell stack is inverted and the second opening for the oxidizer gas after the fuel cell stack is inverted overlap. (iii) The first opening for the refrigerant before the fuel cell stack is inverted and the second opening for the refrigerant after the fuel cell stack is inverted overlap. With this configuration, it is possible to more easily reverse at least one selected from the group consisting of the fuel gas flow direction inside the fuel gas port, the oxidizer gas flow direction inside the oxidizer gas port, and the refrigerant flow direction inside the refrigerant port.

[0138] (Technology 5) The device further comprises a first joint provided in the first opening for fuel gas, a second joint provided in the second opening for fuel gas, a third joint provided in the first opening for oxidizer gas, a fourth joint provided in the second opening for oxidizer gas, a fifth joint provided in the first opening for refrigerant, and a sixth joint provided in the second opening for refrigerant, wherein the first joint is capable of connecting the first opening for fuel gas to the fuel gas supply path and the first opening for fuel gas to the fuel gas discharge path, the second joint is capable of connecting the second opening for fuel gas to the fuel gas discharge path and the second opening for fuel gas to the fuel gas supply path, and the third joint is capable of connecting the oxidizer A fuel cell system according to any one of the technologies 1 to 4, wherein a first opening for gas can be connected to the oxidizer gas supply path, and the first opening for oxidizer gas can be connected to the oxidizer gas discharge path; the fourth joint can be connected to the second opening for oxidizer gas and the oxidizer gas discharge path, and the second opening for oxidizer gas can be connected to the oxidizer gas supply path; the fifth joint can be connected to the first opening for refrigerant and the refrigerant supply path, and the first opening for refrigerant can be connected to the refrigerant discharge path; and the sixth joint can be connected to the second opening for refrigerant and the refrigerant discharge path, and the second opening for refrigerant can be connected to the refrigerant supply path. With such a configuration, it is easy to reverse the flow direction of fuel gas inside the fuel gas hole, the flow direction of oxidizer gas inside the oxidizer gas hole, and the flow direction of refrigerant inside the refrigerant hole.

[0139] (Technology 6) The fuel cell system according to any one of the technologies 1 to 5, wherein the fuel cell stack further comprises a first current collector plate, a second current collector plate, a pair of first terminals for power extraction protruding from one opposite side of the first current collector plate, and a pair of second terminals for power extraction protruding from one opposite side of the second current collector plate, and the plurality of fuel cell cells are sandwiched between the first current collector plate and the second current collector plate. Such a configuration is particularly effective, for example, in the fuel cell system according to the technology 5.

[0140] (Technology 7) A fuel cell system according to Technology 6, wherein a power harness is detachably attached to one of the pair of first terminals, an insulator is detachably attached to the other of the pair of first terminals, a power harness is detachably attached to one of the pair of second terminals, and an insulator is detachably attached to the other of the pair of second terminals. With such a configuration, terminals that are not used during operation of the fuel cell system can be insulated.

[0141] (Technology 8) The fuel cell system according to any one of the technologies 1 to 7, wherein the at least one fuel cell stack includes a first fuel cell stack and a second fuel cell stack, and the structure or element includes a structure that allows the first fuel cell stack and the second fuel cell stack to be interchangeable. Such a configuration eliminates the need for, for example, a special design to invert the first fuel cell stack and the second fuel cell stack.

[0142] (Technology 9) A maintenance method for a fuel cell system comprising a fuel cell stack including a plurality of fuel cell cells, and having at least one fuel cell stack having fuel gas holes, oxidizer gas holes, and refrigerant holes that extend in the thickness direction of the fuel cell cells and penetrate the plurality of fuel cell cells, The fuel cell comprises a membrane electrode assembly including an anode, a cathode, and an electrolyte membrane containing metal ions. After performing an operation in which fuel gas is circulated through the fuel gas holes, oxidizer gas is circulated through the oxidizer gas holes, and refrigerant is circulated through the refrigerant holes, the operation includes reversing at least one selected from the group consisting of the flow direction of fuel gas inside the fuel gas holes, the flow direction of oxidizer gas inside the oxidizer gas holes, and the flow direction of refrigerant inside the refrigerant holes. Maintenance methods for fuel cell systems.

[0143] This configuration can improve the durability of the electrolyte membrane containing metal ions.

[0144] (Technology 10) The fuel cell system includes a fuel gas supply path connected to a first fuel gas opening located at one end of the fuel gas port, a fuel gas discharge path connected to a second fuel gas opening located at the other end of the fuel gas port, an oxidant gas supply path connected to a first oxidant gas opening located at one end of the oxidant gas port, an oxidant gas discharge path connected to a second oxidant gas opening located at the other end of the oxidant gas port, a refrigerant supply path connected to a first refrigerant opening located at one end of the refrigerant port, and a second refrigerant opening located at the other end of the refrigerant port. A maintenance method for a fuel cell system according to Art 9, further comprising a refrigerant discharge path connected to a first fuel gas opening and a fuel gas supply path connected to a second fuel gas opening; connecting the oxidizer gas discharge path to a first oxidizer gas opening and a oxidizer gas supply path to a second oxidizer gas opening; and connecting the refrigerant discharge path to a first refrigerant opening and a refrigerant supply path to a second refrigerant opening. Such a configuration can reduce the cost required to obtain the above-mentioned effects.

[0145] (Technology 11) A maintenance method for a fuel cell system according to Technology 10, wherein the inversion includes inverting the fuel cell stack so as to rotate it with respect to a pivot axis; connecting the fuel gas discharge path to the first fuel gas opening and the fuel gas supply path to the second fuel gas opening after the fuel cell stack has been inverted; connecting the oxidizer gas discharge path to the first oxidizer gas opening and the oxidizer gas supply path to the second oxidizer gas opening after the fuel cell stack has been inverted; and connecting the refrigerant discharge path to the first refrigerant opening and the refrigerant supply path to the second refrigerant opening after the fuel cell stack has been inverted. With such a configuration, even if the metal ion content in the planar direction of the electrolyte membrane becomes uneven due to operation over a certain period of time, the metal ion content in the planar direction of the electrolyte membrane can be made uniform by performing this maintenance method.

[0146] (Technology 12) A method for maintaining a fuel cell system according to any one of the technologies 9 to 11, wherein the at least one fuel cell stack includes a first fuel cell stack and a second fuel cell stack, and the inversion includes swapping the first fuel cell stack and the second fuel cell stack. Such a configuration eliminates the need for, for example, a special design for inverting the first fuel cell stack and the second fuel cell stack. [Industrial applicability]

[0147] The technology disclosed herein is useful for electrochemical devices such as secondary batteries, fuel cells, and hydrogen generation devices. Furthermore, the technology disclosed herein is applicable to solar power generation facilities, fuel cell facilities, battery storage facilities, and systems that supply power by linking commercial power sources, and is applicable to environmental protection initiatives such as RE100 (Renewable Energy 100%). [Explanation of Symbols]

[0148] 10 Membrane electrode assembly 10a First side 10b 2nd side 12 Electrolyte membrane 13 Anodes 14 Anode catalyst layer 15 Anode gas diffusion layer 16 Cathode 17 Cathode catalyst layer 18 Cathode gas diffusion layer 19 Frame 20 Anode Separators 30 Cathode Separators 40 Fuel gas flow path 401 Part 1 402 Part 2 41 Fuel gas port 411 Part 1 412 Part 2 41a 1st opening 41b 2nd opening 42 Fuel gas supply routes 43 Fuel gas emission pathways 45 First joint 46. ​​Second joint 50 Oxidizer gas flow path 501 Part 1 502 Part 2 51 Oxidizing agent gas holes 511 Part 1 512 Part 2 51a 1st opening 51b 2nd opening 52 Oxidizer gas supply route 53 Oxidizer gas emission pathway 55 Third joint 56. Fourth joint 60 Refrigerant flow path 601 Part 1 602 Part 2 61 Refrigerant holes 611 Part 1 612 Part 2 61a 1st opening 61b 2nd opening 62 Refrigerant supply route 63 Refrigerant discharge route 65. Fifth joint 66. Sixth joint 71a,71b 1st terminal 72a,72b 2nd terminal 81 First insulating plate 82 Second insulating plate 91 First clamping plate 92 Second clamping plate 100 fuel cell cells 100a First side of multiple fuel cell cells 100b Second side of multiple fuel cell cells 200 fuel cell stacks 201 First Fuel Cell Stack 202 Second Fuel Cell Stack 200a First side 200b 2nd side 210, 211, 212 Electrical component group 250, 251, 252 power generation units 300,400 fuel cell systems 301 First Subsystem 302 Second Subsystem 110,111,112 Fuel gas supply sources 120, 121, 122 Oxidizer gas inlet 130,131,132 Refrigerant supply source X axis FS fulcrum shaft Ga fuel gas Gc oxidizing gas Mc Refrigerant

Claims

1. A fuel cell stack comprising a plurality of fuel cell cells, wherein fuel gas holes, oxidizer gas holes, and refrigerant holes are formed that extend in the thickness direction of the fuel cell cells and penetrate the plurality of fuel cell cells, A structure or element that reverses at least one selected from the group consisting of the fuel gas flow direction inside the fuel gas hole, the oxidizer gas flow direction inside the oxidizer gas hole, and the refrigerant flow direction inside the refrigerant hole, Equipped with, The fuel cell includes a membrane electrode assembly comprising an anode, a cathode, and an electrolyte membrane containing metal ions. Fuel cell system.

2. A fuel gas supply path connected to a first opening for fuel gas located at one end of the fuel gas hole, A fuel gas discharge path connected to a second fuel gas opening located at the other end of the aforementioned fuel gas hole, An oxidant gas supply path connected to a first opening for oxidant gas located at one end of the oxidant gas hole, An oxidizing gas discharge path connected to a second opening for oxidizing gas located at the other end of the aforementioned oxidizing gas hole, A refrigerant supply path connected to a first refrigerant opening located at one end of the refrigerant hole, A refrigerant discharge path connected to a second refrigerant opening located at the other end of the aforementioned refrigerant hole, Furthermore, The aforementioned structure or element is A structure that allows the fuel gas discharge path to be connected to the first opening for fuel gas, and the fuel gas supply path to be connected to the second opening for fuel gas. A structure that allows the oxidizing gas discharge path to be connected to the first opening for the oxidizing gas, and the oxidizing gas supply path to be connected to the second opening for the oxidizing gas, A structure that allows the refrigerant discharge path to be connected to the first refrigerant opening and the refrigerant supply path to be connected to the second refrigerant opening. The fuel cell system according to claim 1, comprising at least one selected from the group consisting of the following.

3. The aforementioned structure or element is A structure that allows the fuel cell stack to be rotated and inverted with respect to a pivot axis, A structure that, after inverting the fuel cell stack, allows connecting the fuel gas discharge path to the first fuel gas opening and the fuel gas supply path to the second fuel gas opening. A structure that allows the oxidizer gas discharge path to be connected to the first opening for the oxidizer gas and the oxidizer gas supply path to be connected to the second opening for the oxidizer gas after the fuel cell stack has been inverted, and A structure that, after inverting the fuel cell stack, allows the refrigerant discharge path to be connected to the first refrigerant opening and the refrigerant supply path to be connected to the second refrigerant opening. At least one selected from the group consisting of, The fuel cell system according to claim 2, including the above.

4. The fuel cell system according to claim 3, wherein in a plan view along the thickness direction, at least one selected from the group consisting of (i), (ii), and (iii) below is satisfied. (i) The first opening for fuel gas before the fuel cell stack is inverted and the second opening for fuel gas after the fuel cell stack is inverted overlap. (ii) The first opening for the oxidizer gas before the fuel cell stack is inverted and the second opening for the oxidizer gas after the fuel cell stack is inverted are in an overlapping state. (iii) The first opening for the refrigerant before the fuel cell stack is inverted and the second opening for the refrigerant after the fuel cell stack is inverted overlap.

5. A first joint provided in the first opening for the fuel gas, A second joint provided in the second opening for the fuel gas, A third joint is provided in the first opening for the oxidizing gas, The fourth joint provided in the second opening for the oxidizing gas, A fifth joint provided in the first opening for the refrigerant, A sixth joint is provided in the second opening for the refrigerant, Furthermore, The first joint is capable of connecting the first opening for fuel gas to the fuel gas supply path, and is also capable of connecting the first opening for fuel gas to the fuel gas discharge path. The second joint is capable of connecting the second opening for fuel gas to the fuel gas discharge path, and is also capable of connecting the second opening for fuel gas to the fuel gas supply path. The third joint is capable of connecting the first opening for the oxidizing gas to the oxidizing gas supply path, and is also capable of connecting the first opening for the oxidizing gas to the oxidizing gas discharge path. The fourth joint is capable of connecting the second opening for the oxidizing gas to the oxidizing gas discharge path, and is also capable of connecting the second opening for the oxidizing gas to the oxidizing gas supply path. The fifth joint is capable of connecting the first opening for the refrigerant to the refrigerant supply path, and is also capable of connecting the first opening for the refrigerant to the refrigerant discharge path. The fuel cell system according to claim 1, wherein the sixth joint is capable of connecting the second opening for refrigerant to the refrigerant discharge path, and is also capable of connecting the second opening for refrigerant to the refrigerant supply path.

6. The aforementioned fuel cell stack is First current collector plate and The second current collector plate and A pair of first terminals for power extraction protrude from opposite sides of the first current collector plate, A pair of second terminals for power extraction protrude from each opposite side of the second current collector plate, Furthermore, The fuel cell system according to claim 1, wherein the plurality of fuel cell cells are sandwiched between the first current collector plate and the second current collector plate.

7. A power harness is detachably attached to one of the pair of first terminals, and an insulator is detachably attached to the other of the pair of first terminals. The fuel cell system according to claim 6, wherein a power harness is detachably attached to one of the pair of second terminals, and an insulator is detachably attached to the other of the pair of second terminals.

8. The at least one fuel cell stack includes a first fuel cell stack and a second fuel cell stack, The fuel cell system according to claim 1, wherein the structure or element includes a structure that allows the first fuel cell stack and the second fuel cell stack to be interchangeable.

9. A maintenance method for a fuel cell system comprising a fuel cell stack including a plurality of fuel cell cells, and having at least one fuel cell stack having fuel gas holes, oxidizer gas holes, and refrigerant holes that extend in the thickness direction of the fuel cell cells and penetrate the plurality of fuel cell cells, The fuel cell comprises a membrane electrode assembly including an anode, a cathode, and an electrolyte membrane containing metal ions. After performing an operation in which fuel gas is circulated through the fuel gas holes, oxidizer gas is circulated through the oxidizer gas holes, and refrigerant is circulated through the refrigerant holes, the operation includes reversing at least one selected from the group consisting of the flow direction of fuel gas inside the fuel gas holes, the flow direction of oxidizer gas inside the oxidizer gas holes, and the flow direction of refrigerant inside the refrigerant holes. Maintenance methods for fuel cell systems.

10. The aforementioned fuel cell system A fuel gas supply path connected to a first opening for fuel gas located at one end of the fuel gas hole, A fuel gas discharge path connected to a second fuel gas opening located at the other end of the aforementioned fuel gas hole, An oxidant gas supply path connected to a first opening for oxidant gas located at one end of the oxidant gas hole, An oxidizing gas discharge path connected to a second opening for oxidizing gas located at the other end of the aforementioned oxidizing gas hole, A refrigerant supply path connected to a first refrigerant opening located at one end of the refrigerant hole, A refrigerant discharge path connected to a second refrigerant opening located at the other end of the aforementioned refrigerant hole, Furthermore, The aforementioned reversal means, The fuel gas discharge path is connected to the first opening for fuel gas, and the fuel gas supply path is connected to the second opening for fuel gas. The first opening for the oxidizing gas is connected to the oxidizing gas discharge path, and the second opening for the oxidizing gas is connected to the oxidizing gas supply path, The refrigerant discharge path is connected to the first refrigerant opening, and the refrigerant supply path is connected to the second refrigerant opening. A method for maintaining a fuel cell system according to claim 9, comprising at least one selected from the group consisting of the following.

11. The aforementioned reversal means, The fuel cell stack is inverted so as to rotate it with respect to the pivot axis, After inverting the fuel cell stack, the fuel gas discharge path is connected to the first fuel gas opening, and the fuel gas supply path is connected to the second fuel gas opening. After inverting the fuel cell stack, the oxidizer gas discharge path is connected to the first opening for the oxidizer gas, and the oxidizer gas supply path is connected to the second opening for the oxidizer gas, and After inverting the fuel cell stack, the refrigerant discharge path is connected to the first refrigerant opening, and the refrigerant supply path is connected to the second refrigerant opening. At least one selected from the group consisting of, A method for maintaining a fuel cell system according to claim 10, including the method described in claim 10.

12. The at least one fuel cell stack includes a first fuel cell stack and a second fuel cell stack, The maintenance method for a fuel cell system according to claim 9, wherein the reversal includes swapping the first fuel cell stack with the second fuel cell stack.

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